56 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu short communication isolation and morphological identification of some indigenous microalgae from ethiopia for phycoprospecting abate ayele1, arumuganainar suresh1,*, solomon benor1, 2 1department of biotechnology, college of biological and chemical engineering, addis ababa science and technology university, addis ababa-16417, ethiopia 2research, community service, technology transfer and tuil directorate, ministry of science and higher education, ethiopia *corresponding author, e-mail: blueyellowsnu@gmail.com abstract bioprospecting of microalgae is one of the latest promising industries because of its high photosynthetic efficiency. microalgae prospects are under limelight not only for its value added applications but also for no competition for food, water and arable land usage. however, the product is still costlier when compared to other organisms which obstruct large-scale phycoprospecting. indigenous microalgae can improve phycoprospecting and it is on high demand. there is a need to isolate and identify the potential native microalgae for local application with ease. besides, biodiversity in ethiopia is intense and not investigated much on microalgae. therefore, this research aims to isolate microalgae from eight different sites including akaki pond, akaki river, kality pond, kality gidb pond, tuludimtu ditch, awash lake, koka lake and sumit ditch. the samples were inoculated to bold’s basal medium and incubated under natural sun light at 25c for 15 days. then microalgae were purified using agar plate and identified morphologically using light microscope. eighteen species of algae were obtained from 12 genera. pediastrum sp., chlorella sp., chlamydomonas sp., scenedesmus sp., chlorogonium sp., oscillatoria sp., anabaena sp., microcystis sp., microspora sp., closterium sp., synechocystis sp., and navicula species were among the identified genera. of these, 8 genera belong to eukaryotic protist and the other 4 comes under prokaryotic cyanobacteria. these ethiopian native species of microalgae can be used effectively for its value added application locally. keywords: microalgae, ethiopia, cyanobacteria, protista, microscope, phycoprospecting. 1. introduction microalgae are ubiquitous and have been evolving on earth for billions of years and responsible for evolution of aerobic organisms including humans by using co2 from the primitive atmosphere and released o2. studies suggested that tiny algae have been producing 70% of atmospheric o2 (walker, 1980). microalgae (2-200 µm) are organisms highly capable of utilizing solar energy and co2 to create biomass and they are the primary producer for majority life on the planet (wilkie et al., 2011). algal species were estimated between 250,000 to millions of which 35,000 species are scientifically recorded. currently about 5,000 algal species are available through culture collections and only 10 to 20 species are cultivated industrially (https://subitec.com/en/fascination-algae-factson-microalgae; raja et al., 2008). in addition, the estimated number of unknown species of algae is projected to be two orders of magnitude more than currently known species (anderson, 1992; norton et al., 1996). it is a stunning vision that how much potential remains waiting in undiscovered species because the group of discovered species is ever growing for its various applications. many researchers recommend that microalgae may hold the key to solve many problems including pollution, hunger, energy, global warming, and diseases in sustainable manner (wilkie et al., 2011). in fact, stuart & hessami (2005) found that a 4000 m3 pond under natural sun light could sequester up to http://www.ejssd.astu.edu/ https://subitec.com/en/fascination-algae-facts-on-microalgae https://subitec.com/en/fascination-algae-facts-on-microalgae abate ayele et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 57 2.2 kiloton of co2 per year with no competition with food crops, not restricted to arable land and portable water, can be grown in salt water and wastewater (suresh et al., 2018), easily adapt conditions, low energy requirement (oswald, 2003), carbon neutral, renewable, used as single cell protein, nutrient supplements, pigments production, biogas (suresh et al., 2013) and antioxidants. in addition, chisti (2007; 2008) found that microalgae can produce 23–55 m3 oil per acre as compared to oil palm (high oil producing plant) which produces only 1.4 m3/acre. with these promising advantages, microalgae industry is not popular in many part of the world including ethiopia due to lack of study on characterization and exploitation. despite intense biodiversity in ethiopia, its utilization is negligible due to inadequate studies. the existing few studies focused on the community structure and primary production of microalgae (damtew etisa et al., 2018; adane fenta & almaz kidanemariam, 2016) and for biodiesel (abebe girma et al., 2016) lately. a very low attention has been given to the indigenous microalgae and its potentials in ethiopia. to propel algal biotechnological applications in any country, one should investigate the native phycological flora and its potential value to industrial scale. therefore, the objective of this study was to isolate microalgae from various sites in ethiopia and identify the isolates based on morphological characteristics. the present study is part of ongoing efforts to screen efficient native microalgal strains for their phycoremediation of industrial pollutants in ethiopia. focusing on microalgae-based processes, the unexplored country of ethiopia is awaiting the opportunity to play its role in phycoprospecting and to contribute to the economy of the country in general. 2. materials and methods 2.1. microalgae sample collection and growth the microalgae water samples were collected from eight sites in ethiopia (akaki pond-akp, akaki riverakr, kality pond-kap, kality gidb pond-kgp (85344.99 n, 384720.98 e), tuludimtu ditchtud (85100 n, 384859.98 e), awash lake-awl (85859.99 n, 40100.01 e), koka lake-kol (82120.86 n, 3903.74 e) and sumit ditch-sud (9019.44 n, 384548.99 e) and 1 ml was inoculated into a 250 ml flask counting 100 ml sterile bold’s basal medium (bbm) and incubated in the lab under natural sun light (day and night cycle) at 25c for 15 days. the culture flasks were manually shaken twice a day. 2.2. microalgae purification and identification bbm grown microalgae were purified using spread and streak plate method and then isolated colonies were inoculated in 100ml bbm and incubated same as mentioned above. purified algae were identified by its morphology using light microscope (labomed, usa) by wet slide mount method at 40x and 100x (oil immersion). the photomicrographs were taken with an iphone camera via ocular lens and followed the janse van vuuren et al., (2006) manual to identify the microalgae genera. 3. results and discussion in this preliminary study a total of 18 microlagal species were isolated using the standard plating techniques, and based on distinguishable morphological characters under light microscopic examination. these strains were preliminary ascribed to the 12 genera, namely, pediastrum sp., kgp, chlorella sp., akr, tud, chlamydomonas sp., awl, scenedesmus sp., kap, kgp, chlorogonium sp., akp, oscillatoria sp., sud, tud, anabaena sp., kgp, kap, microcystis sp., kol, microspora sp., kgp, kap, closterium sp., akp, synechocystis sp., kap, akr and navicula sp., sud. among this, 4 genera belongs to cyanobacterial group (oscillatoria, anabaena, microcystis and synechocystis) which are prokaryotes and other 8 belongs to protist algae of eukaryotes. moreover, 3 out of 18 species were identified as filamentous algae and they resemble the genera of oscillatoria, anabaena and microspora. most of the genera belong to division of chlorophyta (pediastrum sp., chlorella sp., chlamydomonas sp., scenedesmus sp., chlorogonium sp., microspora sp.). interestingly, a diatom (navicula sp.) and charophyta (closterium sp.) species also screened. in general all isolates have some potential application except microcystis sp., which is a disease causing microalgae by producing neurotoxins. figure 1 shows the photograph of isolated microalgal species. abate ayele et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 58 microalgae are available in all existing earth ecosystems, and representing a diverse polyphyletic group of species living in a wide range of environmental conditions and have potential to solve problems in the world. yet they are one of the most poorly understood, characterized and exploited groups of microorganisms on earth (wilkie et al., 2011; raja et al., 2018). in addition, wilkie et al., (2011) suggested that algae has great diversity, however indigenous species are potential candidates for bioprospecting because native species has advantage over type culture and genetically engineered organisms. isolating native microalgae with desirable properties gives robust biological platform for phycoprospecting. native strains come equipped with millions of years of adaptation to the local biotic and abiotic stress (naturally engineered species). through optimization of native species may yield superior organisms for bioresource production. consequently, isolation is a fundamental process to obtain pure cultures and is the first phase towards the screening and selection of microalgae strains with the potential for the value added applications. although morphological analysis is frequently used to identify microalgae, it is inaccurate and very difficult for the identification at the species level, because the relationship between diagnostic morphology and biological species boundaries are largely unknown in many micro-eukaryotes (moniz & kaczmarska 2010). besides, according to yu et al., (2012) the microalgae morphology for the same strain varies in relation to age and culture conditions. recently in ethiopia, etista et al., (2018) found that the chlamydomonas sp., was dominant in lake abaya in all seasons, therefore in our study expected the same species in all samples but observed only in awash lake sample. abebe girma demissie et al., (2016) isolated very different genera such as oedogonium sp., and cladophora sp., from lake abaya and chamo in arab minch, those genus were absent in our sampling sites in addis ababa. in addition of those unique genera some common genera of chlorella sp., and diatoms also identified (abebe girma demissie et al., 2016). in general, our observation disclosed that different sites shown one or two different microalgae species, whereas kality gidb pond sample was contained 4 different genera of microalgae such as pediastrum sp., scenedesmus sp., anabaena sp., and microspora sp. in case of kality pond also shown 4 different genera namely scenedesmus sp., anabaena sp., microspora sp., and synechocystis sp. attractively, the same genera of microalgae were noticed in different site with a little altered morphology, for example scenedesmus sp., and anabaena sp., from kap and kgp sample (figure 1). the cells of scenedesmus sp., from kality pond (kap) observed 4-celled coenobia, while kality gidb pond (kgp) sample showed 8 celled coenobia which is in agreement with van den hoek et al., (1995) description about the scenedesmus sp. in case of anabaena sp. isolated from kap sample shown rectangular cells in the filament while elliptical to sphere shaped cells in kgp sample. adane fenta and almaz kidanemariam, et al., (2016) reported variation of microalgae between sites is due to the difference in water quality, changes in physico-chemical characteristics lead to concomitant qualitative and quantitative changes in microalgae. therefore, the result shows that the sampling sites was characterized by eutrophic mainly as a result of high nutrient loading from surface runoff from domestic, industrial, agriculture and construction near the sampling sites. in another study, metzger and largeau (2005) reported that, within in each chemical race and for the same strain, the morphology of the alga could vary in relation to age and culture conditions. the morphological heterogeneity of the alga makes the microscopic examination difficult and in support this point, trainor (1998) observed scenedesmus species shown diverse morphology under different environmental conditions in accordance with our identification. identification of microalgae is supported by molecular tools would enhance the authentication of classification (moniz & kaczmarska, 2010), therefore, further analysis on its molecular identification under process. abate ayele et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 59 figure 1. microscopic images of microalgae isolated from the different water samples in these isolates, some algae have lot of potential on value added products like single cell proteins (chlorella sp), feed (chlorella sp., navicula sp.), oil producers (chlorella sp., scenedesmus sp., and diatom), wastewater treatment (chlorogonium sp., scenedesmus sp., oscillatoria sp.,) nitrogen fixer as biofertilizer (anabaena sp), pollutants removal, bioindicator (closterium sp.,) and model organisms for study (synechocystis sp., and chlamydomonas sp.). these ethiopian native genera of microalgae can be used effectively for its value added application locally and it’s under investigation. 5. conclusion in this study, eighteen microalgal species were isolated from eight different sites from ethiopia and identified by morphological features and noticed those belong to 12 different genera. among these, 8 genera belong to eukaryotic protist microalgae and other 4 comes under prokaryotic cyanobacteria it includes 3 filamentous algae. some isolates are industrially important such as chlorella, anabaena, diatom, scenedesmus. given the great diversity of microalgae, it is suggested that many native species are potential candidates for local application. further analysis on its molecular identification is needed and its potential phycoprospecting are under process. acknowledgements the support of the directorate of research and technology transfer, addis ababa science and technology university, in funding internal research grant (code no. ica 04/2011) to dr. a. suresh is gratefully acknowledged. chlamydomonas sp., (awl)chlorella sp.,(akr) anabaena sp.,(kap) synecocystis sp., (akr) chlorogonium sp., (akp)pediastrum sp., (kgp) scenedesmus sp., (kap) oscillatoria sp., (tud) scenedesmus sp., (kgp) closterium sp., (akp) microcystis sp., (kol) microspora sp., (kap) navicula sp., (sud) synecocystis sp., (kap) microspora sp., (kgp) anabaena sp., (kgp) oscillatoria sp., (sud) chlorella sp., (tud) abate 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(2012). isolation of a novel strain of monoraphidium sp. and characterization of its potential application as biodiesel feedstock. bioresource technology, 121: 256-262. doi.org/10.1016/j.biortech.2012.07.002\ https://doi.org/10.1016/j.biotechadv.2007.02.001 https://doi.org/10.1016/j.tibtech.2007.12.002 https://subitec.com/en/fascination-algae-facts-on-microalgae https://doi.org/10.1016/j.protis.2009.07.001 https://doi.org/10.2216/i0031-8884-35-4-308.1 https://doi.org/10.2216/i0031-8884-35-4-308.1 https://doi.org/10.1080/10408410802086783 https://doi.org/10.1016/j.enconman.2004.03.009 https://doi.org/10.1016/j.esd.2011.07.010 https://doi.org/10.1016/j.biortech.2012.07.002 27 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper antibacterial steroids from roots of bersama abyssinica fitsum lemilemu, solomon girmay, kebede shenkute, milkyas endale  department of applied chemistry, school of applied natural science, adama science and technology, p. o. box 1888, adama, ethiopia article info abstract keywords: bersama abyssinica steroids phytochemical screening antibacterial activity bersama abyssinica is one of the medicinal plants used traditionally to treat various diseases such as leprosy, wound, diarrhea, fever, eye disease, rabies and tumor/cancer. phytochemical screening test of dichloromethane/methanol (1:1) and methanol extracts revealed the presence of glycosides, alkaloids, tannins, flavanoids, saponins, terpenoids, steroids and phytosterols. silica gel column chromatography separation of dichloromethane/methanol (1:1) root extracts afforded β-sitosterol (1), 7-hydroxysitosterol (2) and 2-methylamino-butyric acid (3) of which the latter is isolated for the first time from natural source. the crude extracts and isolated compounds were screened for in vitro antibacterial activity against strains of salmonella thphimurium, escherichia coli, bacillus subtilis and staphylococcus aureus. dichloromethane/methanol (1:1) extract, methanol extract and βsitosterol (1) showed moderate activity against e. coli and s. aureus (zone of inhibition 13±0, 13±2 and 12.6±0.48, respectively) and (zone of inhibition 13.6±0.55, 12±2, and 12.5±0.5 mm, respectively) compared to ciprofloxacin (28.6±1.25 and 26±5.1 mm) at 0.5 mg/ml. the structures of compounds were determined by spectroscopic techniques (ir and nmr) and comparison with literature report. 1. introduction the use of traditional medicine for treating human diseases still remains widespread in low income countries with a wide range of biological and pharmacological activities (ajayi et al., 2011; ejele 2010). bersama abyssinica (melianthaceae) is an ever green shrub to small tree up to 18 m tall and its bark, leaf and root decoctions are widely taken as a purgative to treat a range of stomach disorders, such as abdominal pain, colic, diarrhea, cholera, intestinal worms, dysentery, and also for the treatment of rabies, tumour, syphilis, gonorrhea, malaria, rheumatism, aphrodisiac and snake bites (djemgou et al., 2010; lather et al., 2010; kuete et al., 2008; teklehaymanot et al., 2007). b. abyssinica is known in ethiopia as azamer (amharic) and lolchissa (afan oromo) (verdcourt, 1989). it is also distributed in democratic republic of congo, tanzania, mozambique, zambia, zimbabwe, angola, nigeria, ethiopia, kenya, sudan and uganda (mikkelsen and seberg, 2001). previous phytochemical works reported compounds including 3,11,15tetramethyl-2-hexadecen-ol, 7,8-epoxyanostan-11-ol,3acetoxy, pyrogallol, capric ether, 2,3-dimethylfumaricacid, 5-methyl-2-furancarboxyaldhyde, β-sitigmasterol and ethyl iso-allocholate (zekeya et al., 2014; kuete et al., 2008). this study report the isolation, spectroscopic identification, and antibacterial analysis of the roots of b. abyssinica.  corresponding author, e-mail: milkyas.endale@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i1.2020.156 http://www.ejssd.astu.edu/ mailto:milkyas.endale@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i1.xxxx.xx fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 28 2. experimental section 2.1. general tlc was performed using precoated aluminum backed supported silica gel 60 f254 (0.2 mm thickness) and glass supported silica gel 60 f254 (1.0 mm thickness), respectively. phytosterols were detected on tlc stained with the salkowiski reagent. column chromatography was carried out using silica gel 60-120 mesh. 1h and 13c nmr data were obtained in cdcl3 on a bruker avance 400 mhz. 2.2. plant material collection and identification the roots of b. abyssinica were collected in december, 2018 from oromia region arsi zone, asela town, tiyo woreda which is 175 km far from addis ababa, the capital of ethiopia. the plant was identified with the help of botanist and voucher specimen was deposited (fl 001) at national herbarium of ethiopia, addis ababa university. the roots were cut into small pieces, air-dried and ground into a fine powder. 2.3. extraction and isolation air-dried root powder (300 g) was extracted exhaustively with dichloromethane/methanol (1:1) (2 l) for 72 h at room temperature. the marc left was further extracted with methanol (2 l) soaked for 72 h at room temperature. the extracts were evaporated under reduced pressure at 40ºc using rotary evaporator to afford 23.68 g (7.89%) and 30.08 g (10.03%) crude extracts, respectively. the crude dichloromethane/methanol (1:1) crude extract (15 g) was adsorbed on 15 g silica gel and subjected to silica gel (160 g) column chromatography separation. elution was carried out with increasing gradient of ethyl acetate in n-hexane followed by increasing gradient of methanol in dichloromethane. a total of 145 fractions were collected each concentrated under reduced pressure to dryness. fractions that showed similar rf values and the same characteristic color on tlc were combined. fraction 33-38 afforded single spot (β-sitosterol (1, 10.8 mg)) derivative of β-stigmasterol (etoac/n-hexane 1:1 as eluent on tlc with rf value of 0.64). fraction 22-26 afforded single spot (7-hydroxy-β-sitosterol (2, 9.3 mg, etoac/n-hexane 3:7 as eluent on tlc with rf value 0.85). fractions 42-79 afforded 2-methylbutyric acid (3, 26.5 mg, etoac/n-hexane 8:2 as eluent on tlc with rf value of 0.6). 2.4. phytochemical screening test 2.4.1. test for flavonoids: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 10 ml of ethyl acetate was added and heated for 3 min using steam bath. the mixture was filtered, and mixed with 1 ml of dilute ammonia solution. formation of intense yellow color ratifies the presence of flavonoids (sofowora and debiyi, 1978). 2.4.2. test for saponins: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 5 ml of distilled water was added and shaken while heating to boil. frothing showed the presence of saponins (evans and trease, 1989). 2.4.3. test for phenols: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 5 drops of 2 % of fecl3 were added and formation of bluish green to black color indicates the presence of phenols (roopashree et al., 2008). 2.4.4. test for tannins: the crude extracts (dcm: meoh (1:1) and meoh extract) (0.5 g each) was boiled in 10 ml of water in a test tube and filtered. to the filtrate, 5 drops of 0.1 % fecl3 were added to give a brownish green or a blue-black color which confirms the presence of tannins (ayoola et al., 2008). 2.4.5. test for terpenoids (salkowski test): dcm/meoh (1:1) and meoh crude extracts (0.5 g) were mixed with 2 ml of chloroform and 3 ml concentrated h2so4 carefully to form a layer. a reddish brown coloration of the interface was formed to show positive results for the presence of terpenoids (ugochukwu et al., 2013). 2.4.6. test for steroids: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 10 ml of chloroform and 10 ml of concentrated h2so4 were added by sides of the test tube. the upper layer turns red and h2so4 layer showed yellow with green fluorescence indicating the presence of steroids (alhadi et al., 2015). 2.4.7. alkaloids (wagner’s test): dcm/meoh (1:1) and meoh crude extracts (0.5 g each) were dissolved individually in wagner’s reagent (iodine in potassium iodide). formation of brown/reddish precipitate was examined (sadoon et al., 2014). fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 29 2.4.8. detection of phytosterols (salkowski’s test): to dcm/meoh (1:1) and meoh crude extracts (0.5 g each), 10 ml of chloroform was added and filtered. to the filtrate, 5 drops of concentrated h2so4 was added, shaken and examined for the appearance of the golden yellow color (roopashree et al., 2008). 2.4.9. test for anthraquinones (borntrager's test): dcm/meoh (1:1) and meoh crude extracts (0.5 g each) were boiled with concentrated hydrochloric acid for few minutes in water bath and filtered. the filtrate was allowed to cool and equal volume of chcl3 was added to it. few drops of ammonia were added to the mixture and heated in water bath. formation of rosepink color was inspected (roopashree et al., 2008). 2.5. antibacterial testing 2.5.1. preparation of discs containing extracts the same concentrations of 0.5 mg/ml were prepared from the extract, isolated pure compounds and the standard. the concentration was incorporated into sterile agar-disc diffusion and dried at 37°c. the agar disc was weighed carefully to confirm the exact amount of the extract and isolated pure compounds being incorporated (compared to preweighed blank discs). 2.5.2. bacterial culture escherichia coli was isolated from stool specimens collected from clinic and identified according to routine cultural properties and biochemical tests. four strains of each were included in the study. a few colonies from the overnight culture of eosin methylene blue (emb) agar was transferred into approximately 4-5 ml tripticase soy broth (tsb) medium. the broth was incubated at 37 °c for 3-4 h, and the turbidity of suspension was adjusted to that of 0.5 mcfarland barium sulfate standards. the standard suspension was used for both qualitative and quantitative antibacterial assays. 2.5.3. bacterial susceptibility testing standardized inoculums (0.5 mg/ml) were introduced on to the surface of sterile agar plates, and a sterile glass spreader was used for even distribution of the inoculums. sterile agar-disc diffusion previously soaked in a known concentration of extract or pure compound (0.5 mg/ml per disc) was carefully placed at the center of the labeled seeded plate. the same procedure was used for all the mrsa strains used. the plates were incubated aerobically at 37°c and examined for zones of inhibition after 24 hr. the inhibition zones were measured with a ruler and compared with the control disc (disc containing only physiological saline). strains of human pathogen microorganisms used in this study were as follows: two gram-negative bacteria, escherichia coli, salmonella thphimurium and two gram-positive bacteria staphylococcus aureus and bacillus subtilis. the bacterial stock cultures were incubated for 24 h at 37°c on nutrient agar medium (adama science and technology university, department of applied biology, adama). the bacterial strains were grown in the mueller–hinton agar (mha) plates at 37°c. the agar was melted (50°c), and the microorganism cultures were then added aseptically to the agar medium at 45°c in plates and poured into sterile petri dishes to give a solid plate. all these experiments were performed in triplicate. the plates were incubated for 24-48 h at 37°c for bacteria. the inhibition zones produced by the plant extracts were compared with the inhibition zones produced by commercial standard antibiotics (ciprofloxacin). one dilution (0.5 mg/ml) of b. abyssinica extract, pure compound, and standard drugs was prepared in dmso using nutrient agar tubes. mueller–hinton sterile agar plates were seeded with indicator bacterial strains (1.3 x 108 cfu/ml) and allowed to stay at 37°c for 3 h. control experiments were carried out under similar conditions by using ciprofloxacin for antibacterial activity as a standard drug. the zones of growth inhibition around the disks were measured after 24 h of incubation at 37°c for bacteria. the sensitivities of the microorganism species to the plant extract and isolated pure compounds were determined by measuring the sizes of inhibitory zones (including the diameter of disk) on the agar surface around the disks, and values < 6 mm were considered as not active against microorganisms. dmso used as negative control during the whole test on bacteria. the results were expressed as mean value ± standard deviation (sd) (murai et al., 1995). the results are calculated as averages of triplicate tests. the zone of inhibitions in all cases were includes the diameter of the wells. fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 30 3. result and discussion 3.1. phytochemical screening phytochemical screening test of dichloromethane/ methanol (1:1) and methanol roots extracts revealed the presence of alkaloids, flavonoids, phytosterols, phenols, steroids, tannins, terpenoids, coumarins, anthraquinones, terpenes and saponins in both extracts, whereas, saponins were found to be absent in methanol extract (table 1). the presence of these secondary metabolites may be attributed to the traditional use of the plant to treat various diseases. 3.2. characterization of compounds compound 1 was isolated as white solid with melting point 134-136°c and rf value of 0.64 (50% etoac in nhexane as eluent). the 1h nmr spectrum (table 2) showed a series of proton signal at δ 1.0-1.8 due to overlapping of methylenes and methines, a characteristic frame work of steroid. oxygenated sp3 methine proton was observed at δ 3.68 (m, 1h, h-3) which is a characteristic of steroids with hydroxyl group at c-3 position. olefinic proton was observed at δ 5.3 suggesting that the proton is next to methylene. the presence of six methyl groups at δ 0.68, 0.93, 0.83, 0.81, 0.84 and 1.01 is also in agreement with the steroidal nucleus. the 13c nmr spectrum (table 2) revealed the presence of twenty nine carbon signals which is a characteristic feature of triterpenes. the 13c nmr and dept-135 spectra displayed the presence of six methyl carbon signals which resonated at δc 11.9, 14.0 18.8, 19.2, 19.4 and 19.8. eleven methylene carbon signals were observed at δc 21.1, 23.1, 25.9, 27.9, 28.3, 31.9, 32.0, 35.5, 37.3, 39.8 and 42.3 in (table 2). presence of five methine carbons (δc 48.0, 48.30, 50.5, 55.3 and 38.1), two olefinic carbons (δc 143.8 and 121.2), of which the former suggests sp2 quaternary carbon, and two sp3 quaternary carbon signals (at δc 36.2 and 42.8) were also confirmed. oxygenated sp3 methine was observed at δc 76.8 (c-3), in agreement with oxygenation pattern of steroids at c-3. thus, based on the above spectral data and comparison with literature, the structure of the compound was identified as βsitosterol (1) (chaturvedula and prakash, 2012; anjoo et al., 2011; pateh et al., 2008). ho 1 12 7 19 26 27 23 24 20 16 1328 1 compound 2 was isolated as white solid (mp: 135137°c) with rf value of 0.6 (50% etoac in n-hexane as eluent). the 1h nmr and 13c nmr spectra displayed comparable spectral feature to that of β-sitosterol except additional peak observed at δc 79.1 suggesting the presence of additional sp3 oxygenated methine. comparison with literature reports and with nmr features of β-sitosterol, compound 2 was identified as 7hydroxy-β-sitosterol (2). table 1: phytochemical screening tests of crude extracts of dcm: meoh (1:1) and meoh (100%) key: dcm=dichoromethane and meoh=methanol phytochemical screening test dcm:meoh(1:1) extract meoh extract alkaloids wagner’s test + + flavonoids ammonia test + + phytosterols salkowski’s test + + steroids salkowski’s test + + phenols ferric chloride test + + tannins gelatin test + + terpenoids salkowski’s test + + anthraquinones borntrager's test + + terpenes salkowski test + + saponins froth test + fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 31 table 2: 1h (cdcl3, 400 mhz) and 13c nmr (cdcl3, 100 mhz) spectral data of β-sitosterol (1) position δh (δ in ppm) δc chaturvedula and prakash, 2012 1 37.3 37.2 2 31.9 31.6 3 3.18 (1h, t) 71.4 3.53 (dd, 1h, j = 4.5, 4.2, 3.8 hz) 71.7 4 42.3 42.2 5 143.8 140.9 6 5.38 (1h, t) 121.2 5.36 (t, 1h) 121.9 7 32.0 32.1 8 33.1 32.1 9 50.4 50.3 10 36.2 36.7 11 21.1 21.3 12 39.8 39.9 13 42.8 42.6 14 56.8 56.9 15 25.9 26.3 16 28.3 28.5 17 56.1 56.3 18 36.2 36.3 19 0.91 (d, 3h, j = 6 hz) 19.4 0.93 (d, 3h, j = 6.5 hz) 19.2 20 35.5 34.2 21 27.9 28.4 22 45.9 46.1 23 23.1 23.3 24 0.85 (t, 3h) 14.0 0.84 (t, 3h) 12.2 25 2.06 (m, 1h) 29.2 29.4 26 0.96 (d, 3h, j = 6 hz) 19.8 0.83 (d, 3h, j = 6.4 hz) 20.1 27 0.97 (d, 3h, j = 6 hz) 19.2 0.81 (d, 3h, j = 6.4 hz) 19.6 28 0.65 (s, 3h) 18.8 0.68 (s, 3h) 19.0 29 0.99 (s, 3h) 11.9 1.01 (s, 3h) 12.0 ho 1 12 7 19 26 27 23 24 20 16 13 10 28 oh 2 compound 3 was isolated as a white solid with rf value of 0.7 (n-hexane/etoac (8/2) as eluent. the 1h nmr spectrum showed (table 3) the presence of one terminal methyl protons at δ 1.27 (3h, t) suggesting it is adjacent to methylene. the spectrum also displayed a multiplet methine signal at δh 3.5 (q, 1h), methylene at δh 2.36 (2h, t) and methyl at δh 2.8 (3h, m) where the former suggests a methine protons next to a carbonyl of carboxylic acid and also connected to hetroatom whereas the later suggests methyl attached to hetroatom. the 13c nmr spectrum with the help of dept-135 (table 3) revealed the presence of five well resolved carbon signals of which one carbonyl carbon (δc 179.2), methyl (δc 17.6), methine (δc 48.7), one methylene (δc 29.0) and methyl (δc 30.7). its dept-135 spectrum displayed that signal at δc 29.0 pointing down attributed to methylene signal (c-3). thus, based on the above spectral data the compound was found to be 2methylamino-butyric acid (3) isolated for the first time from a natural source. fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 32 table 3: 1h and 13c nmr spectral data of compound 3 ho o hn 1 2 3 3 table 4: zone of bacterial growth inhibition diameter (mm) sample name zone of inhibition (mm) mean ± standard deviation e. coli s. thyphimerium s. aureus b. subtlis dcm/meoh (1:1) extract 13±0.00 11.6±0.48 13±2.00 12.3±1.25 meoh extract 13.6±0.55 12±0.00 12±2.00 11.6±0.48 β-sitosterol (1) 11.6±0.55 11.6±0.48 12.5±0.50 11±0.00 7-hydroxy-β-sitosterol (2) 12.5±0.48 10.6±0.48 12.5±0.50 11±0.82 2-methylamino-butyric acid (3) 11.3±0.48 11± 0.82 11.5±0.50 11±0.00 ciprofloxacin 28.6±1.25 28.6±0.94 26±5.1.00 34.3±0.94 3.3. antibacterial activity the antibacterial activity of the crude extracts of dcm:meoh(1:1), meoh and isolated compound were examined at a concentration of 0.5mg/ml against four pathogenic bacterial strains. promising antibacterial activity was observed for dcm:meoh (1:1) and methanol extracts against e. coli, s. thyphimerium, s. aureus and b. subtlis with zone of inhibition of 13±0, 11.6±0.48, 13±2, and 12.3±1.25, respectively, for dcm: meoh extract and 13.6±0.55, 12±0, 12±2 and 11.6±0.48, respectively, for methanol extract. 7hydroxy-β-sitosterol (2) showed promising antibacterial activity against e. coli and s.aureus with zone of inhibition of 12.6±0.48 and 12.5±0.5, respectively, compared to ciprofloxacin 28.6±1.25 and 26±5.1 (table 4). 4. conclusion for decades traditional medicines have been used and continued to be an alternative approach on treatment for various diseases caused by protozoan, bacteria, fungi, viruses and helminthes. currently, the growing interest of consumers in substances of natural origin in association with the increasing concern of potentially harmful infectious disease has directed to a rising interest in the use of plant extracts as functional ingredients in many pharmaceutical products. b. abyssinica is one of these medicinal plants used traditionally to heal various infectious diseases. the phytochemical screening tests showed that crude extracts of root barks b. abyssinica plants are rich in alkaloids, flavonoids, saponins, phenols, tannins, terpenoids, steroids, phytosterols and glycosides. silica position δh (multiplicity) 13c nmr (δc in ppm) dept-135 (δc in ppm) 1 175.1 2 3.5 (1h, m) 49.4 49.4 3 2.3 (2h, m). 29.0 29.0 4 1.27 (3h, t). 17.6 17.6 5 2.8 (3h, s) 30.7 30.7 fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 33 gel column chromatography separation of the dcm:meoh (1:1) crude extract furnished two triterpenoids named β-sitosterol (1), 7-hydroxy-βsitosterol (2) and 2-methylamino-butyric acid (3). the extracts and isolated compounds were evaluated in vitro for antibacterial activity using the disc diffusion method against e coli, s. aureus, s. thphimurium and b. subtilis. moderate antibacterial activity was observed for dcm/meoh (1:1) and methanol extracts against e. coli, s. thyphimerium, s. aureus and b. subtlis with zone of inhibition of 13±0, 11.6±0.48, 13±2, and 12.3±1.25, respectively, for dcm/meoh (1:1) extract and 13.6±0.55, 12±0, 12±2 and 11.6±0.48, respectively, for methanol extract. 7-hydroxy-β-sitosterol (2) showed moderate antibacterial activity against e. coli and s. aureus with zone of inhibition of 12.6±0.48 and 12.5±0.5, respectively, compared to ciprofloxacin 28.6±1.25 and 26±5.1. acknowledgment the authors acknowledge adama science and technology university, adama, ethiopia for funding part of the work. temesgen asefa (staff of department of applied biology, adama science and technology university) is duly acknowledged for his assistance during antibacterial assay. reference ajayi, i.a., ajibade, o., oderinde, r.a., (2011). preliminary phytochemical analysis of some plant seed. research journal of chemical sciences, 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dennetia tripetala g., baker”, asian journal of plant science research, 3:10-13. fitsum lemilemu et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 34 verdcourt, b., (1989). the national herbarium, addis ababa university, ethiopia and the department of systematic botany, uppsala university, sweden, in: hedberg i, and edwards s eds, flora of ethiopia, 511-512. zekeya n., chacha m., shahada f., kidukuli a., (2014). analysis of phytochemical composition of bersama abyssinica by gas chromatography-mass spectrometry. j pharmacognosy phytochemistry. 3(4): 246-52. 47 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu research paper assessment of service quality and customers’ satisfaction in addis ababa city light rail transit belayneh bogale, eskedar gizat department of public management, kotebe metropolitan university, p. o. box 31248, addis ababa, ethiopia article info abstract article history: received 24 september 2020 received in revised form 24 april 2021 accepted 02 may 2021 the issue of urban mass transportation is becoming the center of cities' sustainable development and revitalization strategies. hence, conducting a scientific inquiry into customers' satisfaction and service quality in urban light rail transport is vital to make policies and intervention measures instrumental and valid. the purpose of the study was to assess service quality and customer satisfaction in urban transport service delivery with particular reference to addis ababa city light rail transit. to this end, the service performance (servperf) model has been adapted and utilized as measurement constructs and a quantitative approach has been employed. the study was a descriptive and explanatory type involving the analysis of data collected through questionnaires from passengers of the light rail transit. to analyze background information of respondents and their perception of service quality, descriptive statistics were applied. besides, the study has utilized correlation and regression analysis. the finding of the study shows that the customers are moderately satisfied with assurance and responsiveness while they are dissatisfied with affordability, tangibility, reliability, and empathy. the correlation analysis of service quality dimensions (tangibility, reliability, responsiveness, assurance, empathy, and affordability) has shown, they all are positively correlated to overall service quality. besides, all service quality dimensions have a significant effect on customer satisfaction implying that the higher the quality of service, the higher is the level of customers' satisfaction. in light of this, it is recommended that addis ababa light rail transit can improve customers’ satisfaction by working on quality. keywords: customer satisfaction light rail quality services service performance 1. introduction the urban transport sector is an important component of the economy and a major component used for development. economic opportunities have been increasingly related to the mobility of people, goods, and information. when transport systems are efficient, they provide economic and social opportunities and benefits that result in positive multiplier effects such as better accessibility to markets, employment, and additional investments (rodrigue, 2017). as world bank (2008) states, “cities are the engines of economic growth in most developing countries, and that urban corresponding author, e-mail: belayneh.bogale@kmu.edu.et https://doi.org/10.20372/ejssdastu:v8.i2.2021.298 transport is the oil that prevents the engine from seizing up”. transportation improvement can make cities much more efficient and productive. according to peter (2006), the earlier transport policies of the developed countries were oriented to automobile developments. however, because of environmental and financial issues, the concept of sustainable mobility became a trend and directed to new policies for mobility in cities. due to increased travel demands, struggle for space and livability in the cities, growing carbon emissions from the transport sector, and http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i2.2021.298 belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 48 the need to enhance mobility, a new transportation system called light rail system (lrs), was developed (peter, 2006). the lrs is used in both developed and developing countries in the last decades. it is documented that in european countries, and also in many cities in asia, latin america, and africa (like algeria, egypt, and tunisia), lrs has been popular (african development bank, 2015). addis ababa city is the diplomatic center of africa and the seat for many international organizations. addis abba city is responsible for 60 percent of the country's industrial production and 50 percent of its gdp (wondifiraw zerihun et al., 2015; world bank, 2015). therefore, the role of transport in running the economic, social, and political activities of the city smoothly could not be easily valued. most trips in addis ababa are carried out using public transport and on foot. sixty percent of the population are walkers (saba engineering p.l.c., 2005). the major modes of public transportation in addis ababa are buses, taxis, and light rail. transportation service is being delivered to the public through public buses (anbesa and sheger), and other privately owned vehicles, such as higer buses, small buses, taxis, and the addis ababa light rail transit service. the limited number of buses and taxis in addis ababa has resulted in low quality, safety, and accessibility of the service delivery across the city (kumar and barrett, 2008). users are hardly able to access public transport during peak hours or bad weather conditions (tilahun fenta, 2014). sometimes the commuters are required to pay an extra fare or forced to disembark when only midway through their route (mintesenot gebeyehu and takano, 2007; kumar and barrett, 2008). this has resulted in customer dissatisfaction in general. on the other hand, the population of addis ababa is increasing significantly and the number of people who work in the city and reside out of the city has been increasing over time. as the population increases, the number of passengers using public transport also increases. to accommodate the increasing number of passengers, the transport service is expected to expand. however, the supply of transport services is not proportional to demand. due to the limited number of mass transport options, city’s dwellers who cannot afford other modes of transport are exposed to walk long distances on foot and longer line of waiting and travel time (saba, 2005). as one component of the ethiopian growth and transformation plan (gtp i), the government launched addis ababa light rail transit (aa-lrt) back in september 2015 to alleviate the transportation problem in the city. despite all its contribution, based on casual observations and the available limited studies, (haileyesus alebachew, 2016; habtamu gebeyehu, 2017) during peak hours, the demand for light rail transport extremely exceeds the supply of service resulting longer waiting times and hard struggle to get the service. moreover, trains are often overcrowded, which exposes passengers to accidents, suffocation, possible pickpocketing, and communicable diseases. this has made it difficult for the elderly, pregnant, patient, and persons with disabilities to use the lrs. however, most of the previous studies failed to measure the level of customers' satisfaction in urban light rail passenger service scientifically. therefore, whether customers are satisfied with the services provided by aa-lrt is a critical knowledge gap that needs to be addressed. failure to conduct scientific customer satisfaction and quality survey, and use the finding as input for decision making may jeopardize the improvement of the service. thus, this study was carried out to investigate service quality and customers' satisfaction in urban transport service delivery with particular emphasis on aa-lrt. to this end, literature availed several models for measuring service quality. service quality (servqual) and servperf are among the models which researcher are using most often. both models use five service quality dimensions and empirical studies (e.g. parasuraman et al., 1988; haileyesus, 2016; habtamu, 2017) also show that service quality dimensions have relations with service quality. however, some studies have applied a certain pragmatic modification of the models. servperf model is an improvised model of parasurman's servqual. while servperf dwells on perceived service quality, the servqual approach has got to elements-expectation and perception. having reviewed both theories and empirical studies on service quality and customer satisfaction, the following conceptual framework (figure 1), modified servperf, has developed for this study. belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 49 figure 1: conceptual framework developed by the researchers based on reviewed literature 2. materials and methods 2.1. research design this study aims to reach a generalization based on the quantitative measurement of patterns of behavior. therefore a quantitative approach has been utilized. besides, as the study mainly involves describing quantitative data and showcasing the casual relationship between variables, descriptive and explanatory research methods have been used. to achieve the research objectives, the researchers have conducted the survey using a structured questionnaire. 2.2. sample and sampling procedure aa-lrt has two lines i.e. east-west line from ayat to torhailoch and the south-north line from kality to menelik ii square. the two lines have a total number of 39 stations. from these stations, 22 stations stretched from north-south and the remaining 17 stations in the second line. form a total of 39 stations, a total of 10 stations were selected based on researchers' judgment and proportional distance from the main terminals. accordingly, 6 stations from the north-south (minilik ii, abenet, mexico, temenja yazh, nefas silk i, and kality) and 4 stations from east-west (torhailoch, hayahulet ii, management institute, and ayat) were targeted in the study. the study used cochran's (1963) sample size determination formula for an unknown or large sample to come up with a sample size of 384. once the sample size was determined the total sample was equally apportioned to the 10 stations resulting in 39 judgmentally selected passengers in each station. though 384 respondents were distributed, 14 were found to be incomplete and void; hence the data analysis was carried out using 370 questionnaires. to ensure representativeness, respondents who were found at the stations waiting for the service during peak, off, and weekend times were inculcated. target respondents of this study were passengers that were within the age range between 15 and 65, living in addis ababa, and experienced in using light rail transport. the ages range 15 to 65 years old was chosen because people at this age have a routine commute travel behavior. from the age of 15, teenagers usually have to go to a school that is not in their neighborhood. after the age of 65, people usually do not have routine behavior because of pension. 2.3. instruments the data for this study were collected through a selfadministered structured questionnaire. the first part of the questionnaire was the demographic profile of respondents, the second part incorporated the 25 items modified servperf questions (cronin and taylor, 1992; philop and hazlette, 1997), and the third part included questions about overall service quality and overall customer satisfaction. all items were rated by respondents on a five-point likert scale. the questionnaire was designed in amharic, the working language of the country, in order to avoid language barrier. the questionnaires were distributed and tangibility customer satisfaction reliability empathy responsiveness assurance affordability belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 50 recollected by well-trained data collectors at the cite data collection. the study has relied on the modified servperf model developed in 1992. service quality gurus (e.g cronin and taylor, 1992; philop and hazlette, 1997) confirmed that servprf is suitable in scrutinizing customers' perceptions of service quality. thus, through the utilization of a modified servpref model, the study has conducted a descriptive survey using a structured questionnaire. 2.4. reliability and validity cronbach’s alpha is used in this study to assess the internal consistency of the data collection instrument. cronbach's alpha (coefficient alpha), ranges in value from 0, meaning no consistency, to 1, meaning complete consistency (all items yield corresponding values). the result of the overall scale reliability coefficient alpha for this study is r = 0.917 and the coefficient alpha for all six items of modified service quality found to be more than 0.702. the measures exceed the usual recommendation of alpha = 0.70 for establishing the internal consistency of the scale. to ensure validity, survey questions were reviewed by experts and it was proven that scales had an adequate content validity. 2.5. data analysis once the questionnaire was collected and returned, the researchers coded and entered data into statistical package for the social sciences version 23 (spss-23) software. to find out the level of service quality and customers’ satisfaction in aa-lrt, the appropriate descriptive statistics (means and standard deviations) were used to examine passengers’ appraisal of the quality of service provided by the transit and their satisfaction with the services provided. to examine the relationship between perceived service quality and customers satisfaction in aa-lrt, the pearson correlation was conducted to study the relationship between perceived service quality dimensions and overall customer satisfaction. to analyze the effect of service quality dimensions on customer satisfaction, a multiple regression analysis was carried out to examine the direction and strength of relationships among the constructs. 3. results and discussion 3.1. level of service quality and customers satisfaction table 1 depicts respondents' perception towards modified service quality dimensions, overall service quality, and general customer satisfaction. the perception of respondents on assurance (m = 3.02) is better than other service quality dimensions and greater than moderate (m = 3.0). this is followed by responsiveness, affordability, and tangibility with an approximately moderate mean score of 3.0, 2.98, and 2.94 respectively. on the other hand, empathy and reliability are the least perceived values from the modified service quality dimensions with a mean score of 2.92 and 2.9, respectively. table 1: descriptive statistics the mean perception of the customers on the assurance is relatively good (m = 3.02) which shows that as far as trustworthiness, courtesy, friendly approach, knowledge of the staff and installing a sense of safety among commuters during travel are concerned customers perceive that the service is slightly greater than moderate (m = 3). similarly, the service quality perception of respondents on responsiveness (m = 3.0), affordability (m = 2.98), and tangibility (m = 2.94) are the second, third, and fourth better dimensions with a mean score of approximately moderate. while responsiveness, as a servprf dimension, is related to informing customer their rights and responsibilities and the willingness, ability, and promptness of employees in their response to customers’ queries; affordability measures reasonableness of the fare given the service, availability of weekly, monthly or season based ticketing and comparative fairness of the n mean std. dev. tangibility 370 2.9356 .51063 reliability 370 2.9038 .49060 responsiveness 370 3.0074 .53797 assurance 370 3.0230 .56861 empathy 370 2.9189 .56924 affordability 370 2.9820 .51386 overall service quality 370 2.92 .696 customers satisfaction 370 2.90 .683 belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 51 fair in comparison with other forms of transportation. similarly, tangibility (m = 2.94) reflects the comfort of train station facilities, cleanliness of the inside environment of the train, professional appearance of the staff, accessibility of visual display materials, the comfort of seats, deployment of modern equipment. however, customers’ perception of the remaining servprf dimension, empathy (m = 2.91), and reliability (m = 2.9) is the rate below moderate (average). this indicts that the quality of the service for customers with special needs and attention (disables, pregnant, children, and elderly) and accuracy of ticketing services, punctuality, safety/security of service, staff shows interest in solving problems and overall correctness of the service are found to be low. generally, the mean perception of respondents with overall service quality and customer satisfaction is below moderate (m = ~2.9). assessing these mean scores in line with anton's (1997) three zones of perception of service performance, aa-lrt customers' satisfaction index is slightly lower than moderate which is below the tolerance (acceptance) zone. 3.2 correlation between servprf dimensions and customer satisfaction correlation analysis was used to check the strength of the relationship among various variables. in this study, the correlation of servprf dimensions, overall service quality, and level of customers' satisfaction was analyzed. the value of the correlation coefficient could take values between -1 and 1 which means the coefficient is ranging from being negatively correlated (-1) to uncorrelated (0) and to positively correlated (1). the pearson correlation result indicates the magnitude of relationships in the following categorization (dancey and reidy, 2004): the relationship is weak if the coefficient is between 0.10 and 0.3, moderate when it is between 0.40 and 0.6, and strong when it is between 0.70 and 1.00. when the correlation analysis coefficient is equal to 1, the pearson result considers it as a perfect correlation. as can be seen from table 2 all service quality dimensions have a positive relationship with overall service quality and customer satisfaction through the magnitude of the relationship differ among service quality dimensions. there is a strong positive significant correlation between customer satisfaction and overall service quality (r = 0.895, p<0.001, df = n-1 = 369). all of the dimensions, reliability (r = 0.824), assurance (r = 0.821), tangibility (r = 0.811), affordability (r = 0.779), and empathy (r = 0.702) have a high coefficient value showing the existence of a significant and strong relationship with overall service quality. table 2: pearson correlation among measures customers satisfaction overall service quality tangibility responsiveness assurance reliability empathy affordability customers satisfaction 1 overall service quality 0.895 ** 1 tangibility 0.877** 0.811** 1 responsiveness 0.808** 0.778** 0.763** 1 assurance 0.842** 0.821** 0.804** 0.803** 1 reliability 0.880** 0.824** 0.829** 0.821** 0.840** 1 empathy 0.745** 0.702** 0.713** 0.687** 0.729** 0.742** 1 affordability 0.844** 0.779** 0.809** 0.768** 0.803** 0.820** 0.711** 1 **. correlation is significant at the 0.01 level (2-tailed). belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 52 on the other hand, all service quality dimensions have a positive relationship with the level of customer satisfaction albeit with varying degrees. in light of this, reliability (r = 0.88), tangibility (r = 0.87), affordability (r = 0.844), assurance (r = 0.842), responsiveness (r = 0.808), and empathy (r = 0.745) have a correlation coefficient values showing the existence of a significant and strong relationship with customer satisfaction (significant at 0.001 level (2-tailed)). the implication of the analysis result is that the better the quality of service with all the six modified quality dimensions, the higher the level of addis ababa light rail customer satisfaction. finally, the relationship between the overall service quality and customer satisfaction is also analyzed using correlation analysis. the result shows that overall service quality and customer satisfaction have both positive and significant relationships with a correlation coefficient value of 0.895. in effect this confirms that service quality and customer satisfaction are closely related (parasuraman et al., 1988) explaining service quality is an antecedent of satisfaction (cronin and taylor, 1992). table 3: results of multiple regressions between tangibles, reliability, responsiveness, assurance, empathy, affordability and customer satisfaction coefficientsa model unstandardized coefficients standardized coefficients t sig. colinearity statistics b std. error β tolerance vif (constant) -0.759 0.079 -9.646 0.000 tangibility 0.323 0.047 0.241 6.803 0.000 0.227 4.400 reliability 0.272 0.056 0.195 4.862 0.000 0.177 5.649 responsiveness 0.041 0.042 0.033 0.993 0.321 0.265 3.779 assurance 0.030 0.045 0.025 0.667 0.505 0.205 4.869 empathy 0.045 0.033 0.038 1.396 0.163 0.388 2.579 affordability 0.180 0.045 0.136 3.970 0.000 0.244 4.093 a dependent variable: customers satisfaction table 4: result of anova test anovaa model sum of squares df mean square f sig. 1 regression 149.094 6 24.849 392.119 0.000b residual 23.004 363 0.063 total 172.097 369 a dependent variable: respondents’ overall satisfaction b predictors: (constant), affordability, empathy, responsiveness, tangibility, assurance, reliability table 5: model summary model r r2 adjusted r2 std. error of the estimate 1 0.931a 0.866 0.864 0.252 a predictors: (constant), affordability, empathy, responsiveness, tangibility, assurance, reliability belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 53 as table 3 shows, the tolerance values of all independent variables are above 0.1 and the vif values are below 10 which the two values together confirm none existence of a multicollinearity problem in the regression analysis under consideration. the subsequent anova test and model summary tables also confirm the same. moreover, tangibility, reliability, responsiveness, assurance, empathy, and affordability (the independent variables) impact the dependent variable (customers' satisfaction) are positive as values of coefficient β confirm. this means service quality dimensions contribute positively and significantly to customers' satisfaction. tangibility, reliability, and affordability have a relatively higher effect with the value of β = 0.241, β = 0.195, and β = 0.136 on customers' satisfaction followed by empathy, responsiveness, and assurance with the value of β = 0.038, β = 0.033, and β = 0.025 respectively. this shows that while tangibility, reliability, and affordability have a positive and significant effect on customers' satisfaction; empathy, responsiveness, and assurance have positive but insignificant impacts on customer satisfaction. 4. conclusions and recommendations 4.1. conclusions urban light rail transport service delivery by aalrt has been scrutinized in this study. modified service quality dimensions particularly the serpref was used as a construct to measure customer satisfaction of the same entity by applying various statistical tools. it merits wrap up the finding in the forthcoming statements so that their implication will be pinpointed clearly. in the descriptive analysis portion of the paper, customers' perceptions were measured in terms of mean values. in line with this except for two quality dimensions, assurance, and responsiveness, where the satisfaction is slightly greater than moderate and moderate respectively, for the remaining quality dimensions customers are not satisfied with a mean score below moderate (5 points likert mean of 3.0). hence, customers of addis ababa light rail transit are not satisfied with affordability, tangibility, reliability, and empathy dimensions. with regards to the overall service quality and customer satisfaction, the customers are not satisfied with addis ababa light rail transit urban transport service delivery. however, as the mean scores are closer to moderate (5 points likert mean of 2.9) with planned intervention it is possible to reach at least a moderate level of satisfaction. the correlation analysis of service quality dimensions (tangibility, reliability, responsiveness, assurance, empathy, and affordability) shows, they all are positively significantly correlated to the quality of the overall service. the inference of this is that the better the quality of service with all the six modified quality dimensions, the higher the level of addis ababa light rail customer satisfaction. besides, all service quality dimensions have a positive and significant relationship with the level of customer satisfaction. the strongest relationship is observed on reliability and tangibility. the overall service quality correlation with customer satisfaction is very strong and significant (r = 0.895). in conclusion, focusing on tangibility and responsiveness is necessary to fill the gap the correlation coefficient showed which would bring value addition to the customer service and ultimately secure a better level of customer satisfaction. regarding the effect analysis, it is found out that independent variables (service quality dimensions) have a significant impact on customers’ satisfaction (dependent variables) but with varying degrees. from this, it is clear that addis ababa light rail transit can improve customers’ satisfaction by working on quality. 4.2. recommendations in the service delivery process, addis ababa light rail transit is not as empathetic as customers require. as clearly indicated in the quality dimension of empathy, addis ababa light rail transit has to know the best interest of its customer and attempt to address it. hence, the company has to revisit its manner of service delivery for customers with special needs and the friendliness of the service to all segments of the society (disabled, pregnant, children, and elderly). to this end, it is necessary to give attention to individual customer interests and requirements rather than apply, ‟one fits all” approach. in the same token, the reliability of rail service delivery was found to be below moderate. this implies that the accuracy of ticketing services, punctuality, safety/security of service, staff interest in solving problems, and overall correctness of the service are belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 54 found below. hence, organizations should strive to fulfill promises and pay attention to the results. the service quality perception of respondents on responsiveness, affordability, and tangibility was rated approximately moderate. to improve the modest score of responsiveness the company should work on the willingness; ability and promptness of employees in their response to customers' queries and in effectively communicating customers' rights and responsibilities. similarly to improve the moderate perceived quality score of affordability which measures reasonableness of the fare given the service, availability of weekly, monthly, or season-based ticketing the company has to commensurate service quality vis-a-vis the fare and design alternative ticketing package. likewise, tangibility which reflects the comfort of train station facilities, cleanliness of the inside environment of the train, accessibility of visual display materials, comfort of seats, and deployment of modern equipment has scored approximately moderate perceived quality. to improve the tangibility score the company has to make timely maintenance of train facilities and visual display materials. it is a well-established fact that satisfied customers are keys to higher economic returns and long-term business success (kristensen et al., 1992 as cited in munusamy et al., 2010). as this study confirms, in addis ababa light rail context service quality is the biggest component that impacts customer satisfaction. the management of addis ababa light rail transit has to give major attention to quality to bring about a better satisfaction level. acknowledgments first, researchers would like to express our deepest gratitude and appreciation to kotebe metropolitan university for sponsoring our research project. second, researchers would like to express our acknowledgment to addis ababa light rail transit for unreserved cooperation, facilitation, and support during fieldwork. particularly, researchers are indebted to targeted respondents for their cooperation. moreover, we would like to extend our acknowledgment to all data collectors. reference african development bank (2015). rail infrastructure in africa: financing policy options. transport, urban development & ict department. anton, j. 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(1988). servqual: a multiple-item scale for measuring customer perceptions of service quality. journal of retailing, 64(1): 12-40. peter, c. (2006). “terms in the uk” http://www.thetrams.co.uk/tramsinuk.php. retrieved 22 feb 2018 rodrigue, j.p (2017). the geography of transport systems (4th ed) new york: routledge saba engineering p.l.c. (2005). urban transport study and preparation of pilot project for addis ababa. addis ababa, ethiopia: unpublished. http://www.thetrams.co.uk/tramsinuk.php.%20retrieved%2022%20feb%202018 belayneh bogale and eskedar gizat ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 55 wondifiraw zerihun, kibret kibret and wakaiga, j. (2015). ethiopia: african economic outlook. addis ababa, ethiopia: african development bank. world bank (2015). addis ababa, ethiopia: enhancing urban resilience. city strength: resilient cities program. washington dc. world bank (2008). cities on the move: a world bank urban transport strategy review. united states of america: the world bank, washington dc. 14 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper phycoremediation of synthetic dyes in an aqueous solution using an indigenous oscillatoria sp., from ethiopia galle gezahegn gelebo1, lidiya hailu tessema1, kalkidan tadesse kehshin1, hable haileselassie gebremariam1, eyerus tigabu gebremikal1, melkame tamiru motuma1, abate ayele1, deribe getachew1, solomon benor1,2,  , arumuganainar suresh1,3,  1department of biotechnology, college of biological and chemical engineering, addis ababa science and technology university, addis ababa-16417, ethiopia. 2research, community service, technology transfer and tuil directorate, ministry of science and higher education, ethiopia. 3centre of excellencebioprocess and biotechnology, addis ababa science and technology university, addis ababa-16417, ethiopia article info abstract article history: received 15 january 2019 received in revised form 14 march 2020 accepted 13 april 2020 synthetic dyes usages are inevitable, but they are recalcitrant and toxic, hence need treatment before discharge. lately, phycoremediation of dyes gained more attention due to its valueadded benefits, however, it need more investigation of indigenous species for ease. therefore, the aim of the study was to isolate indigenous microalgae from elias tesfaye textile factory runoff, addis ababa. the sample was inoculated to bold’s basal medium and incubated for 15 days and the dominant colonies were purified and identified using a microscope. the identified isolate, oscillatoria sp., which belongs to prokaryotic filamentous cyanobacteria was checked for the dye removal efficiency and biomass production using synthetic dyes of malachite green (mg), methylene blue (mb) and safranin (sf). the axenic cultures of oscillatoria sp., was inoculated (0.2 g/l) with various concentrations of dyes (1-5 mg/l) and incubated under sunlight for 5 days and analyzed the residual color absorbance and biomass production. a maximum of 93% dye color was removed in mg, followed by mb (66%) and sf (52%). interestingly, the biomass was increased 3.75 times in mb dye (0.75 g/l), while 3.1 and 1.9 times in mg (0.63 g/l) and sf (0.38 g/l), respectively. it seems that the oscillatoria sp., was decolorizing the dyes by utilizing as nutrients and shown unique potentials on different dyes. yet, more studies are needed for the exact mechanism of removal and large scale application. this ethiopian native species of microalgae can be used effectively for the phycoremediation of synthetic dyes locally. keywords: biomass cyanobacteria microalgae phycoremediation synthetic dyes 1. introduction synthetic dyes are visible chemical, water-soluble, complex organic compounds, xenobiotic, recalcitrant and are more stable to light, heat, oxidizing agents and difficult to remove from contaminated water  corresponding author (equally contributed), e-mail: suresh.suresh@aastu.edu.et, solomonbenor@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.186 (brahmbhatt and jasrai, 2016). nevertheless, the uses of synthetic dyes are inevitable and significantly increase in the various industries (textiles, tannery, paper, printing and dyeing, food and cosmetics) for as coloring agents. http://www.ejssd.astu.edu/ mailto:suresh.suresh@aastu.edu.et,%20solomonbenor@gmail.com mailto:suresh.suresh@aastu.edu.et,%20solomonbenor@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxxxx galle gezahegn et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 15 in fact, over 10,000 different synthetic dyes are used and approximately 0.7 million tons of dyes are synthesized every year worldwide (andrade and andrade, 2018) in which 40% (0.28 million) is discharged in effluents annually (jin et al., 2007). this huge amount of dye pollutants in the effluent causes serious environmental problems. for instance, the dye can affect the photosynthetic activity of aquatic organisms by reducing the sunlight penetration and its chemicals (metals, chloride) can accumulate in the ecosystem and leads to human systems and causes various diseases from mild (allergic, vomiting, nausea, etc.) to serious diseases (cancer, malfunctions of organs, etc.) (crini and badot, 2008). therefore, it is important to safeguard the ecosystem from such contaminants. in order to overcome these problems, many physical and chemical methods are applied such as adsorption, precipitation, photolysis, oxidation and reduction, electrochemical treatment, filtration, coagulation and flocculation (alaguprathana and poonkothai, 2017). however, these physicochemical processes are costly, not able to remove completely, release toxic metabolites and generate secondary sludge which may cause secondary pollution (wang et al., 2019; zhou et al., 2019). the use of biological systems (bacteria, yeast, fungi, microalgae, and plant) for the removal of synthetic dyes is an attractive alternative to the bioremediation for the effluent containing dyes (solís et al., 2012). biological discoloration can occur via absorption, enzymatic degradation or a combination of both (wu et al., 2012) and has advantages over physiochemical methods mainly in terms of cost, environmental benignity, easy and safe operation–green chemistry concept (andrade and andrade, 2018). among biological systems, microalgae have raised eminence, due to its photoautotrophic nutrition and their potential to remove pollutants, co2 mitigation and produce high valueadded chemicals, concurrently (suresh and benor, 2019; suresh et al., 2019). therefore, many researchers isolated and recommend that the microalgae biomass may hold the key to solve dye contamination in aqueous solutions worldwide (vikrant et al., 2018; alaguprathana and poonkothai, 2017; solís et al., 2012). the environmental problem caused by hazardous dyes is particularly important in ethiopia because of the high utilization of synthetic dyes in industries particularly leather and textile, where periodic releases of liquid effluent to the water bodies occur without proper treatment (zinabu et al., 2018). therefore, need a potential, preferably biosystems to solve the dye pollutants and petite attention has been given to the indigenous microalgae in ethiopia and its dye decolorization. given the great diversity of microalgae (two orders of magnitude more than currently known species of 35,000), it is suggested that ethiopian native microalgae species (naturally modified) are potential candidates for local application with ease (abate ayele et al., 2019). therefore, the objective of this study was to isolate microalgae from local textile factory runoff and its potential in removing synthetic dyes of malachite green (mg), methylene blue (mb) and safranin (sf) from aqueous solutions and biomass production. the present study is a part of ongoing efforts to screen efficient native microalgae strains for their phycoremediation of industrial pollutants in ethiopia. 2. materials and methods 2.1. microalgae sample collection and identification the microalgae sample (~100 ml volume) was collected from elias tesfaye textile factory runoff (ettfr), addis ababa, and small amount (around 1 ml sample) was inoculated into 100 ml sterile bold’s basal medium (bbm) and incubated in the lab under sunlight at 25°c for 15 days with light and dark cycle. the culture flasks were manually shaken twice a day for 5-10 seconds. the microalgae were purified using spread plate assay and then dominant colonies were picked and inoculated into 100 ml bbm and incubated the same as above. the axenic culture was stored in a bbm slant for later use. a purified alga was identified morphologically using a light microscope (labomed, usa) by a wet slide mount method at 450x magnification. the photomicrographs were taken with a camera via the ocular lens and followed the van vuuren et al. (2006) manual to identify the microalgae genera. 2.2. microalgae dye removal efficiency and biomass production the dominant filamentous microalgae of oscillatoria sp., (ettfr) was tested for the dye removal efficiency. the synthetic dyes of mg, mb and sf were prepared (1 g/l stock) in deionized water and galle gezahegn et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 16 mb mg sf control used at five different concentrations (1, 2, 3, 4 and 5 mg/l). ten days old axenic oscillatoria sp., (ettfr) culture was taken and rinsed with sterile deionized water and small amounts equal to 2 mg (dry weight) of culture was introduced into the test tubes (10-12 mm diameter) which contains 10 ml of sterile bbm with different concentration of dye and the control was without dye. inoculated tubes were incubated as mentioned previously. decolonization of dyes was monitored by taking one ml of sample, centrifuged at 3000 rpm for 5 min and the supernatant used for taking the absorbance (600 nm) in the uv-spectrophotometer (biochrom, libra s80pc, uk) at different day intervals (0, 3 and 5 days). the amount of dye removal efficiency (re) was calculated based on eq. 1 and the re was compared with previous reports. 𝑅𝐸 (%) = 𝐴𝑖−𝐴𝑓 𝐴𝑖 × 100 (1) where ai and af are initial and final absorbance of the dyes at 600 nm. remaining, microalgal biomass was collected after 5 days of growth and filtered using pre-weighed whatman no.1 filter paper. then the filter paper was rinsed with distilled water (5 ml) and dried at 60c in a hot air oven for overnight then weighed for algal biomass production. 3. results and discussion 3.1. microalgae isolation and identification in this study, a dominated and fast-growing native species of oscillatoria (ettfr) was isolated from elias tesfaye textile factory runoff, addis ababa (figure 1, control). the isolated prokaryotic cyanobacterial microalgae of oscillatoria sp., (ettfr) was dark green and shown long filamentous consisting of a single row of cells and un-branched filaments with a very thin gelatinous sheath. the filaments were similar in shape except the apical cell which is convex at the tip. this ettfr oscillatoria sp., was isolated from the dye industry wastewater, therefore it has been naturally adapted to the particular environment. based on this circumstance, this train could utilize or reduce the synthetic dyes effect and produce more biomass. previous studies were also shown on the oscillatoria sp., which dominated the industrial effluents of other countries (el-sheekh et al., 2009) and preferred for the dye remediation (priya et al., 2011; saha et al., 2010). besides, wilkie et al., (2011) envisaged that the microalgae are the solution for the world problems (pollution, hunger, fuel, disease) and said many studies have been done using commercial strains rather than the native species towards the above problems. indigenous species are having more advantages over custom strains and genetically modified organisms. 3.2. synthetic dyes removal and biomass production textile wastewater adapted microalgae of oscilltoria sp., (ettfr) was checked for the removal of synthetic dyes of mg, mb, and sf. the clear evidence of dye removal ability by live oscilltoria sp., (ettfr) isolate was shown in figures 1 and 2. figure 1: light microscopic image of oscillatoria sp., (ettfr) with and without synthetic dye treatment (5 mg/l). control; no dye, mg; malachite green, mb; methylene blue and sf; safranin. the picture was taken on the 5th day of incubation at 450x magnification. the dye colors were reduced and almost completely removed on the 5th day of incubation in mg and mb dyes, whereas, in sf, the residual color was visible with the naked eye (figure 2). however, when analyzed using a spectrophotometer, a maximum of 93% of mg color was removed, followed by mb (66%) and sf (52%) on the 5th day of incubation, respectively (figure 3). it seems that the dyes were first adsorbed and disintegrated as seen on the 5th day of culture (figure 1). interestingly, the biomass production was reached at the maximum of 0.75 g/l from 0.2 g/l (inoculums size) in mb dye added, while 0.63 g/l in mg and 0.38 g/l in galle gezahegn et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 17 mg 0 day mg 5th day mb 0 day mb 5th day sf 0 day sf 5th day 1mg/l 2mg/l 3mg/l 4mg/l 5mg/l 1mg/l 2mg/l 3mg/l 4mg/l 5mg/l 10mg/l control 1mg/l 2mg/l 3mg/l 4mg/l 5mg/l 10mg/l control sf, respectively. the maximum biomass was produced up to 3.75 times in mb dye and the least was 1.9 times in sf dye within 5 days. similarly, boduroğlu et al. (2014) also found that the microalgae of gonium sp., biomass was almost doubled in the reactive blue 220 dye added (25 mg/l) medium in 14 days of incubation with 87.7% removal rate. both studies showed that the isolated microalgae were degrading the dyes and used as nutrients because the growth was increased as dye color diminished. at the same time, it might be due to adsorption or bioaccumulation fashion and not the degradation phenomenon. however, figure 1 fairly proved that the disintegration of dyes around the cell wall of the microalgae and the dye color was not dense, whereas it was diluted. it would be an intense color in the case of adsorption or bioaccumulation phenomenon. moreover, the pellets of the culture did not show any dye color after centrifugation that indicated that the oscilltoria sp., (ettfr) mineralized the dyes added. previous studies also supported that the most of the dyes were assimilated as nutrients by degrading using enzymes (dellamatrice et al., 2017; solís et al., 2012; priya et al., 2011; saha et al., 2010). indeed, the same genus (oscillatoria sp.,) from the marine source shown 84% removal of the diazo dye, and acid black dye in 8 days (priya et al., 2011) and 52% decolorization of poly r-478 dyes in 7 days of incubation in a medium free of nitrogen (saha et al., 2010). the dye degrading ability was attributed to the activities of the enzymes such as laccase, polyphenol oxidase, and azoreductase and proved that these dyes were used as a nitrogen source in an oligotrophic environment (priya et al., 2011; saha et al., 2010; el-sheekh et al., 2009). further studies are needed to explore the exact mechanisms of remediation of dye pollutants by oscillatoria sp., (ettfr) for efficient use on large scale. essentially, synthetic dyes are the most common colorant in many industries (textile, paper, leather) and azo dyes contribute to 60– 70% of the total dyes produced (moawad et al., 2003). dyes can be absorbed or adsorbed or transformed or degraded by a variety of microorganisms for the survival (as nutrients, avoid its toxic effect, increase light utilization) (vikrant et al., 2018; solís et al., 2012). among them, microalgae are preferable as it belongs to oxygen-evolving photoautotrophs and therefore, oxygenate the dye effluent and help to reduce the secondary pollution (saha et al., 2010). figure 2: decolorization synthetic dyes of malachite green (mg), methylene blue (mb) and safranin (sf) by filamentous microalgae of oscillatoria sp., in five days of incubation the genus of oscillatoria is a non-heterocystous filamentous cyanobacterium and cannot fix atmospheric nitrogen, therefore, it needs an external nitrogen source for their growth. therefore, it uses an external source of organic compounds such as synthetic dyes, which initially adsorb to the cell wall of the microalgae and finally degrades and consume the released inorganic nutrients. besides, the efficiency of decolorizing is highly influenced by the structure of the dye and the species of algae (omar, 2008). both living and nonliving algae can be used in the phytoremediation of dyes from wastewater with the availability of the biomass (lim et al., 2010; sivarajasekar et al., 2009). it was well proved that the dead microalgae can remove dyes in a short period of time (<1 h) with an ion-exchange or columbic interaction between the algae surface and the dye properties. in case of live algae, for instance, in this study, oscillatoria sp., (ettfr) took 5 days to remove at the maximum of 93% in mg dye at 5 mg/l concentration, while priya et al., (2011) found 8 days to remove 84% in 100 mg/l concentration of azo dye and el-sheekh et al. (2009) observed 81% removal of galle gezahegn et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 18 methyl red (20 mg/l) in 5 days. this clearly indicats that more time is needed for the high concentration of dye pollutants using live biomass, but it is opposite to dead biomass that required less time irrespective of dye concentrations (solís et al., 2012). it is good to mention that less concentration is preferred in live biomass than dead biomass due to the toxicity of dyes otherwise diluted effluent is favored. in support of this phenomenon, boduroğlu et al. (2014) found that the higher removal rate at lower concentrations of synthetic dye using microalgae of gonium sp., and the biomass was affected negatively by the increasing pollutant concentrations, as the decreases in removal rate. on the other hand, more biomass was preferred for more concentrated dye effluent to achieve more removal rates (table 1, boduroğlu et al., 2014). in the case of microalga biosorbents, the ph of the environment played an important role than the dye concentration. for instance, low ph was preferred for the dead biomass that improves its adsorption between dye and biosorbents greatly (srinivasan and viraraghavan, 2010), whereas in live biomass, high ph was preferred which supports the growth of microalgae eventually mineralization of dyes occur and used as nutrients (boduroğlu et al., 2014). different microalgae species have different potential of decolonization efficiency of synthetic dyes as observed from previous studies (table 1). attractively, figure 3: residual dye absorbance percentage and the biomass production of oscillatoria sp., in malachite green (mg), methylene blue (mb) and safranin dye added aqueous solution for five days of incubation with 5mg/l dye concentration. table 1: comparison of synthetic dyes removal potential using live microalgae synthetic dyes microalgae (live) algae inoculated dye concentration incubation removal % reference malachite green oscillatoria sp., 0.2 g/l 5 mg/l 5 days 93% present study methylene blue oscillatoria sp., 0.2 g/l 5 mg/l 5 days 66% present study safranin oscillatoria sp., 0.2 g/l 5 mg/l 5 days 52% present study malachite green chlamydomonas sp., 0.75 g/l 10 mg/l 4 h 99% al-fawwaz and jacon 2011 methylene blue chlorella sp., 0.75 g/l 10 mg/l 4 h 99% al-fawwaz and jacon 2011 malachite green cosmarium sp., 4.5 x 106 cell/ml 10 mg/l 7 h 85% daneshvar et al., 2007 malachite green haematococcus sp., 1 g/l 100 mg/l no data 67% liu et al., 2018 methyl red oscillatoria sp., 1.3 x 105 cell/l 20 mg/l 5 days 81% el-sheekh et al., 2009 orange ii oscillatoria sp., 1.3 x 105 cell/l 20 mg/l 5 days 34% el-sheekh et al., 2009 g-red oscillatoria sp., 1.3 x 105 cell/l 20 mg/l 5 days 10% el-sheekh et al., 2009 acid black i oscillatoria sp., 0.5 g/l 100 mg/l 8 days 84% priya et al., 2011 poly r-478 oscillatoria sp., 500 µl/4.5 ml 75 mg/l 7 days 52% saha et al., 2010 reactive blue 220 gonium sp., 0.21 g/l 25 mg/l 14 days 88% boduroğlu et al., 2014 reactive blue 220 gonium sp., 0.53 g/l 25 mg/l 14 days 97% boduroğlu et al., 2014 black color microalgae mixture 10% inoculum no data 5 days 40% tadele assefa aragaw and abraham asmare 2018 aniline blue chlorella sp., 0.5 g/l 25 mg/l 11 days 58% arteagaa et al., 2018 galle gezahegn et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 19 the non-filamentous microalgae of chlamydomonas and chlorella sp., have shown a more efficient in removing dyes (al-fawwaz and jacon, 2011) than filamentous microalgae (el-sheekh et al., 2009). it might be due to the surface area and the growth rate of the algae which are more and high in non-filamentous microalgae. when using the live biomass for the phycoremedation of dyes, it is important to mention that incubation time is also a critical factor that varies according to the species. i addition to that, wilkie et al., (2011) suggested that indigenous species are potential candidates for bioprospecting because native species have an advantage over type culture and genetically engineered organisms. isolating native microalgae species with desirable properties gives a robust biological platform for phycoprospecting. native strains come equipped with millions of years of adaptation to the local biotic and abiotic stress (naturally engineered species). therefore, the locally adapted potential microalgae isolates are preferred for the large scale application in bioremediation of dyes. here, presented the oscillatoria sp., from ettfr which is a potential microalga for phycoremedation of dyes in geographic conditions of ethiopia. 4. conclusion the discharge of synthetic dyes into the environment has become a matter of grave concern. in this study, a dominant, filamentous, prokaryotic cyanobacterium of oscillatoria sp., (ettfr) was isolated from elias tesfaye textile factory runoff, addis ababa and has shown considerable decolorization of synthetic dyes in live biomass. the maximum of 93% decolorization potential of the native oscillatoria sp., was observed in synthetic dyes of malachite green, followed by methylene blue (66%) and safranin (52%) within 5 days of incubation at 5 mg dye/l concentration. the microalgae biomass production was also reached a significant amount at the maximum of 3.75 times more in methylene blue dye (0.75 g/l), followed by 3.1 times in malachite green (0.63 g/l) and the least was 1.9 times in safranin dye (0.38 g/l) added medium. the oscillatoria sp., shown typical decolorization efficiency for different dyes and it appeared that this native microalga utilized dye as a nutrient. much work is still needed in order to understand the exact mechanism of degradation and the enzyme systems involved and large scale studies. this ethiopian native microalga of oscillatoria sp., (ettfr) is potential candidates for phycoremediation of synthetic dyes at the local application with ease. acknowledgment the support of the directorate of research and technology transfer, addis ababa science and technology university, in funding internal research grant [code no. ica 04/2011] to dr. a. suresh is gratefully acknowledged. reference alaguprathana, m., poonkothai, m. 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(2018). impacts and policy implications of metals effluent discharge into rivers within industrial zones: a sub-saharan perspective from ethiopia. environmental management, 61(4): 700715. 14 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper indigenous knowledge of the shekacho society in enset (ensete ventricosum (welw) cheesman) plantation and management from field to plate alemu gonfa robi1,*, negussie megersa2, tetemke mehari2 1adama science and technology university, department of chemical engineering, school of mechanical, chemical and material engineering, p. o. box 1888, adama, ethiopia 2addis ababa university, department of chemistry, college of natural sciences, p. o. box 1176, addis ababa, ethiopia. * corresponding author, e-mail: alemug4@gmail.com abstract in this study, the indigenous knowledge of the shekacho society in enset cultivation and kocho food production was investigated. although enset has several advantages, only limited population of ethiopians consume the food product mainly due to some uncommon sensory quality parameters and lack of awareness. the shekacho society introduces the plant “mandillo” that greatly improves the quality and palatability of kocho products. to this end, analytical data were collected using semi-closed questionnaires, field observations, interviews and discussion with key informants. local annotations review and enset plant physical structure were also measured. fermentation was carried out by knowledgeable local women quality of the products were evaluated qualitatively using sensory panellist using preference test. descriptive analysis of the enset histories, culture, varieties and uses, showed diversified applications of enset and the detail knowledge of shekacho society inherited in enset cultivation and consumption managements. one hundred fifteen enset local cultivars were identified and grouped into male and female types. the measurement of the parts of enset plant in the study area showed maximum average size in total height, the pseudo stem circumference and its height, leaf height and volume of underground corm (13.1 m, 2.5 m, and 4 m, 9.1 m and 1 m3, respectively). the effect of adding mandillo during enset fermentation resulted in visible physical quality differences of kocho products. the study also showed that enset productivity affected by biotic factors. the descriptive analysis of the data and the corresponding results suggested the existence of a high degree of consistency among the respondents. keywords: enset, fermentation, kocho, mandillo, shekacho. 1. introduction enset (ensete ventricosum (welw.) cheesman) belongs to the order scitamineae, the family musaceae, and the genus ensete, known as false banana, which is widely distributed in eastern and southern africa (bender, 2006). it is cultivated in southern, southwestern and some other parts of the oromia national regional state of ethiopia (brandt et al., 1998; tadese kippe, 2002; temesgen magule et al., 2014). enset is a perennial monocarpic plant with leaves, pseudostem and a large underground corm (tadese kippe, 2002). as it was stated by karin et al. (2005) and ajabu nurfeta et al. (2008), the criteria for differentiation of the phenotype are the size and shape of the pseudostem and leaves, and color of leaf sheaths, midribs, and lamina. the plant grows fairly well between 1100–3000 m above sea level (brandt et al., 1998). a vigorously growing healthy plant can withstand prolonged periods of drought (brihanu abegaz, 1987a). http://www.ejssd.astu.edu/ mailto:alemug4@gmail.com alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 15 out of more than 90 million ethiopians, enset is a staple food for about 15 to 20 million people in mixed subsistence farming systems (tadese kippe, 2002; karin, 2002; temesgen magule et al., 2014). the leaf sheaths and the corm provide starchy food which can be stored for long periods after fermentation. moreover, all parts of the plant are used to provide other useful products for household, agriculture, and traditional medicinal treatments (tadese karin et al., 2005). the major foods obtained from enset are kocho, bulla and amicho. kocho is the bulk of the fermented starchy food obtained from the mixture of the decorticated (scraped) leaf sheaths and grated corm. after initial processing, the mixture is left in the storage pit for 15–30 days during fermentation, and it can further be stored for many months and even for several years. when ready for consumption, kocho is also made to a fermented bread-like food that is consumed in villages as well as for local urban markets (brandt et al., 1998). according to admasu tsegaye and co-worker (2001), kocho yield of enset per unit space and time, in terms of edible dry weight and energy, was much higher than the yields of any other crop cultivated in ethiopia and estimated to range from 17.1 to 33.9 ton ha-1 year1 indicating the potential of this crop for food security. in spite of the fact that kocho is very important source of food, energy and industrial raw materials (temesgen magule, 2009; biruk ayenew et al., 2012), its usage has been limited to only some regions of the country. there are key reasons why kocho is not well appreciated among ethiopians that could be associated with its uncommon inherent sensory attributes characteristics, long fermentation period, lack of awareness and short shelf-life. for instance, non-enset producing areas are not familiar to the odor, taste and flavor of the food. the nutritional and organoleptic qualities of kocho could be process related and are different from place to place. to alleviate such problems and increase safety, quality and shelf-life of the food material, addition of traditional preservatives was noted to be useful (stuart et al., 1986; sahlin, 1999). the traditional preservatives can impart characteristic flavors; have antioxidants as well as antimicrobial activities (smid et al., 1999). traditionally, mandillo (family, asteraceae; genus, crassocephalum; specific epithet, macropappum (sch.bip. ex. a.rich.) s.moore)) has been used by the shekacho society as preservative and fermentation enhancer in kocho production since ancient times. however, there is no proper scientific documentation on this remarkable indigenous knowledge. mandillo has been recorded to be endemic to ethiopia and anherbaceous plant distributed in different regions and transects of the bonga forest (mesfin tadesse, 2004; nune, 2008). the plant was also observed to grow in excess around the sheka zone, gordomo and gore, iluu-abbaa-booraa zone in the oromia national regional state. numerous research findings were performed on enset, such as: enset cultivation and productivity (admasu tsegaye and struik, 2001), microbial dynamics of enset fermentation and spoilage of kocho (brihanu abegaz, 1987b), food security issues (tadese kippe, 2002), biochemical changes during enset fermentation and the effect of altitude on microbial successions (tariku hunduma and mogessie ashenafi, 2011), chemical composition and degradability of enset (ajabu nurfeta et al., 2008), mineral contents and their absorption inhibition factors (melaku umeta et al., 2005), improving the indigenous processing of kocho production (melese temesgen, 2013), enset fermentation in pits and jars (tiruha habte et al., 2013). however, no studies have been considered on the traditional enset fermentation using mandillo to improve the uncommon kocho quality parameters and to enhance fermentation rates. therefore, this study was initiated to qualitatively investigate the indigenous knowledge of enset fermentation practices and to evaluate the existing enset diversity of sheka zone. furthermore, the application of mandillo in enset fermentation process and the major advantages of kocho consumption as well as its contribution towards maintaining food security and environmental protections were investigated. 2. material and methods 2.1. description of the study area the plant (mandillo) sample was collected from masha town. enset samples were collected from two most enset producing districts (masha and andracha), sheka zone, southern nation nationalities and peoples regional state of ethiopia. masha town is located at alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 16 latitude and longitude of 7°44′n and 35°29′e, respectively, with altitude of 2223 m above sea level. semi closed questionnaire composed of eight sections and ninety two questions was prepared in english language, validated with sheka community living in hawassa city and in the research area with the assistance of translators when needed. fifty respondents were purposively selected among the knowledgeable women, farmers, agricultural experts, office holders and cultural leaders. twenty one of the respondents were invited by the zone administrative officials. the remaining twenty nine respondents were selected based on suggestions of the 21 respondents from different villages. the questionnaire was filled in by face to face discussion. parts of enset plant in the study area was measured using tep meter. 2.2. data from different sources and field visit local annotations were also reviewed. interviews were made with knowledgeable individuals among the 50 respondents, 12 farmers and the 2 women involved in fermentation process. pictures of the research areas and available enset plants were taken directly from the farm of twelve farmers. enset local cultivars were listed by their local name exhaustively. 2.3. data from enset fermentation four matured female types (maache) enset plants were purchased from masha town. two knowledgeable women were involved in the fermentation processes, who used their own local materials, including wooden board (matoo), bamboo scraper (maaroo), wooden grater (komixoo), knife (shikkoo) and bucket (dooloo). prior to fermentation, the site was cleared and 1m by 1m in diameter and depth pits (gamoo) were prepared. enset leaves were also selected and exposed to sun to make it stronger and flexible. the knife was sharpened. fermentation processes took place following the traditional methods used by the local society and the earlier works of berhanu abegaz (1987a), tariku hundumaand and mogessie ashenafi (2011). all the leaves (mato), the interlocking leaf sheath (dubo) and dried leaf sheath (kaakiro) were removed from the enset plants. parts of the pseudostem were scraped by maaroo on matoo slanted against a live enset. the corms were pulverized by komixoo. the scraped and the pulverized biomasses were mixed and chopped by knife. the chopped biomass samples were grouped into four equal portions, sealed carefully with the prepared enset leaves and put in the pits of 1 m by 1 m in diameter and depth, separately for nine days. on the same day, the starter culture was prepared from different parts of enset such as shitoo (pre-fermented lower part of midrib), baqqoo (inner soft part of pseudostem), ooqqo (midrib), quuro (squeezed liquid), mundriiqqo (the shoot) and uuxo (amicho or corm). the biomass was prepared in duplicates, for both samples of fermentation with mandillo (1:25 w/v) and without mandillo in the four kiisho-goonos (bowel shaped structures made from underground corm). about 100 g of fresh mandillo stem was added to about 100 km of biomass of kocho to evaluate its effect on product quality and change in fermentation period. the bowels were kept intact to the ground. both groups were sealed off external air with leaf sheath (brihanu abegaz, 1987a) and left for nine days. at the end of the ninth day, all the partially fermented kocho and the starter culture were taken out of the pit and kiisho-goono, respectively. the kocho was kneaded and mixed with the starter cultures along with mandillo (1:1000 w/w) and without mandillo. after mixing, the contents were buried in the pits again for another five days for maturation. on the fifth day, the kocho was removed from the gamoo and pancakes prepared. the quality of kocho was qualitatively evaluated using 30 trained sensory panelist by preference test method on the bases of the texture, taste, ripeness, color, softness, and odor of the pancake against fermentation period of the control and experimental group. 2.4. data analysis descriptive data analysis was followed; focus group discussion data was translated and transcribed. to pronounce the names of the enset plants, processes and products correctly, latin rules of writing was used. enset parts physical measurements were done in replicates and the results were expressed as mean. 3. results and discussion 3.1. descriptive analysis of the historical background of enset and its products alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 17 based on the responses of the study participants, there is no clear indication for how long enset plant has been known by the shekacho society and from where it was introduced. however, the entire respondents unanimously agreed that the histories of existence and usage of enset may linearly coincide with the long years history of the shekacho people. the study subjects have further remarked that in the history of shekacho society, drought and starvation have never been experienced probably because of the established tradition of enset plant cultivation as a major source of food, the presence of dense forests and fertile lands (figure 1). figure 1: patchy forests and enset plants in fetafa; sheka zone. 3.2. classification of enset one hundred fifteen enset local cultivars were identified and classified as male (atina'o) and female (maache) types, out of which sixty one of them were physically observed from the farmer's field and virgin lands (figure 2). figure 2: cultivated (left), wild (right) enset plants. the criterion for classification of enset as male and female, according to the respondents, were based on the structure, size, food quality and tolerance to stresses; but has nothing to do with biological reproductive systems of the plants. one third of them classified as male types, while the remaining found to be female types, as listed down below: male types of enset cultivars: aa'i-barasho, aa'ibosso, aa'i-gudiro, aa'i-noobo, aa'i-yoobo, aajjaro, aajjo, aataro, addo, baacci-barasho, bado, baraadi, baraadi-bosso, barasho, baxxato, bosso, bushuro, ceella-bosso, ceellacho, ceella-gemo, gajji-bosso, ganji-baraso, ganji-noobo, gayaacho, gemo, giillo, goomajjo, gudiro, gushiro, kabbo, necca-gemo, necca-noobo, noobo, obaano, ookko, qattaano, qefibosso, shondi, taato, tafaro, yaafi-bosso and yoobo. female types of enset cultivars: aacho, aa'ishimmo, aakkaro, agane, agani, arakko, ballaa-wusso, buuti, caaccaro, carallo, ceeggacho, ciqqaro, ganjo, geno,giito, goobachi, googashi, gosho, gotano, hiikiwwi, kaa’o, kafi-qeeqqaro, kafiyachi, kawo, keci, maacaa-dami, maaci, maara-tiishi, mashaa-maasho, mashengi, maxaaqo, messo, necca-barasho, nooqo, ogisso, ogiyo, oomano, oomi, ooqo, qasafo, qasiaafo, qebbo, qeeqqaro, qeraaro, qooppiri, qotano, shehi, sheki-qeeqqaro, shicho, shiddo, shiimo, shiishiri, shiisho, shimmo, shirii, shiwo, shukki, shuruddo, shuuri, taawo, tisha-maati, toobbacho, ukkano, waango, wushiro, wusso, xeeyo, ximbirii, yaaho, yeebbo, yeqqo, yooro and yotto. the interviews with key informants indicated that female types are large in number of the available cultivar, but the male types are most commonly available in the farmers' fields, huge in size, more disease and drought resistant and produce higher yields than the female ones. some of the most abundant enset cultivars and commonly used by the farmers are the following: baraadi-bosso, barasho, carallo, gemo, gudiro, maaca-dami, maxaaqo, noobo, shicho, and yeqqo. similar to other zones that cultivate enset plants, the varieties in sheka zone have also been identified by color, structure and size of the different parts of the plant (yemane tsehaye and fassil kebebew, 2006). according to the respondats, medicinal value, disease and drought resistance properties, food and fiber quality and yields are based on the cultivars of enset. furthermore, the study participants described various parts and products of enset as follows: the leaf (maato), leaf sheath (yo’o), midrib (ooqqo), inner soft part of pseudostem (baqqoo), pseudostem (dubo), alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 18 corm/amicho (uuxo), squeezed liquid (quuro), bulla (ittino), kocho, starter culture (kiisho), and fiber (yi’o). it was also learnt that the shekacho society uses enset as food sources, livestock feeds, medicine, household materials and utensils, construction materials, detergent, etc. in addition, dubbo, fusso and qocho (traditional dresses made up of enset fiber for female), and gichoo (an ornamental made up of enset fiber put on the shoulder by male) which are special heritages of shekacho society's traditional clothes. 3.3. cultivation of enset the opinions of the study subjects indicated that the male types enset are primarily cultivated for food source compared to the female types. in this connection, the methods and stages of enset development and cultivation followed by the shekacho society are provided in figure 3. the study participants further indicated that all of the activities related to enset cultivations are the responsibilities of both the females and men. figure 3: enset cultivation at different development stages: a, division of the corm into four parts (baqqo); b, sucker formation (gaamo); c, seedlings (aaco); d, further dispersion of seedlings (uukko); e, final transplantation (tokko); g, seedling production; and f, kocho production. according to the tradition of shekacho people, the first stage in enset cultivation is the removal of the pseudostem from the corm (uuxe-maaco), while the second stage is division of the corm into two or four parts (baqqo) based on its size (figure 3a) to increase the surface area of the corm. the third or an optional stage is either putting the corm into the pit upside down (duukkoo) or it could be left intact to the ground coating with cow dung (ibe-fuutto). contrary to the report by tadese kippe (2002), that indicated about 200 suckers to emerge per enset corm; in the present study, it was learnt that the number of suckers (gaamo) emerged per corm was found to vary from 300–400 following the traditional cultivation method in the sheka zone (figure 3b). the differences in number of suckers may be as a result of differences in enset caltivars, rainfall and soil fertility. then, the suckers grow into seedlings (aaco) and can be dispersed after six to eight months (figure 3c). the seedlings can further be dispersed (uukko) after a year for final transplantation (figure 3d). the plant will then further transplanted (tokko) and allowed to grow until it matures for harvesting (figure 3e) within two to four years of growth period. the harvesting time required by the female types varies from four to five years. however, the male types need longer periods (i.e., six or more years). in addition, based on the traditional knowledge of the local farmers, the spacing required between the two adjacent plants to grow varies from 1.5–2.0 m for male types but 1.0–1.5 m for the female types. according to the information obtained from the experts of the woreda’s agricultural offices, enset plants grow best in the altitude ranging from 1800–3000 m above sea level, unlike the report by brandt et al. (1998) alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 19 who indicated an altitude requirement starting from 1100 m for favorable growth of enset plants. moreover, medium to high rainfall is also preferred for healthy growth of the plants. regarding the sizes of enset plants grown in masha areas, the tallest plant grows to the average height of about 13.1 m while the pseudostem is 2.5 m in circumference and 4 m in height. moreover, the leaves were found to extend up to the height of 9.1 m and 1.2 m in width (figure 4a). the maximum volume of the underground corm was about 1 m3. figure 4: parts of enset (a) and mandillo (b). 3.4. share of women and enset management practices the study participants further indicated that all of the activities related to enset fermentation are the responsibilities of the females. this may be mainly due to the beliefs of the society that if the male even passes by the fermentation area, the fermentation process would fail. furthermore, all the participants agreed that traditionally women add mandillo (figure 4b) when they have inadequate starter culture to enhance fermentation and shorten the fermentation period. moreover food preparations are also on the shoulder of the women. 3.5. outcomes of enset fermentation one of the observations made during the field visits was the traditional enset fermentation processes. particular attention was also given to the effect of introduction of mandillo on the kocho quality (figure 5 a to f). it was further learnt that moderate rainfall is the favorable condition for enset fermentation to obtain underground water to dissolve the mixed materials of starter culture ingredients (figure 5e). figure 5: enset fermentation processes: pulverized corm,(a); scraped pseudostem, (b); mixed and unfermented kocho biomasses, (c); sealed kocho biomass in a pit, (d); starter culture ingredients, (e); and sealed starter culture (f). the semi fermented kocho on the ninth day (figure 6a). the starter culture along with mandillo and without mandillo, respectively (figure 6b). five days after addition of the starter cultures, the final products showed remarkable physical quality a b a b c d e f alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 20 parameters (texture, taste, ripeness, color, softness, and odor) with noticeable differences between fermentation with mandillo (figure 7b) and fermentation without mandillo (figure 7a). accordingly, the respondents preference test unanimously confirmed that the product with mandillo was whiter in color, more acceptable odor and taste, ripened in a shorter time, softer and had finer texture than the product without mandillo. figure 6: a, fermented kocho, b, starter culture without mandillo (right) and with mandillo (left). figure7: kocho fermented without mandillo (a) and with mandillo (b). 3.6. production of enset according to the information obtained from the respondents, the biggest matured male type enset yields 200 to 250 kg kocho, about 30 kg bulla fresh weight and 5 to 8 kg fiber per plant. the yield obtained from the female type is about 60 to 70 kg kocho, 10 to 15 kg bulla and insignificant amount of fiber per plant. the productivity of enset is also estimated to 62.85 to 83.33 ton ha-1 year-1 on wet weight bases, while this quantity is 28.28 to 38.33 ton ha-1 year-1 on dry weight bases. it can be concluded that the yields from the current study area are by far better than that reported by admasu tsegaye and struik (2001). the respondents have also explained that kocho from the female types is softer, more palatable, better in texture and taste, matures earlier and more easily fermented than the male types. it was interesting to learn that the maxaaqo variety, among the female types, is the best quality and prepared for honored guests like son-inlaw, honorable personalities and leaders. kocho, amicho (uuxo), eekko, bulla (ittiino), mixed (bacco) and fiber (yi’o) were also known to be the main products of enset fermentation processes of the study area. 3.7. enset based food products the respondents indicated that from the fermented enset product pancake like bread can be made and consumed with cabbage and animal products based sauces. the study subjects further noted that the pancake like kocho can be served with other foods like injera in the presence of sauce. therefore, according to the tradition of shekacho people, it is known that maxino (pancake) from kocho is “the grace of the table”. other products such as bulla are the best raw material in preparation of kujjo (soup). furthermore, uuxoo (amicho) can be boiled and eaten like potato (david, 2006). on the other hand, uuxoo (amicho) from the female enset type is more acceptable than the male type. arakko, maxaaqo and maacaa-dami are known to be of the best quality uuxoo sources, while only ukkano is considered from the male types of enset. in addition, kujjo (soup), buuxo (porridge) xeesso, kosso, baacuuroo, qaafoo, qoriyo, naakkasho, anjaawuro and buddeno (injera) are some of the cultural foods eaten along with milk, kale, cabbage, meat and different type of stews. 3.8. shelf-life study according to the respondats, the findings of the current study confirmed that the shelf-life of kocho, produced by shekacho women was found to extend from one month to one year by simple packaging with enset leaves. however, the shelf-life can also be extended from one to two years by wrapping with enset a b a b alemu gonfa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 21 leaves and dipping into a deep water body such as slowly running river. based on further information obtained from the respondents, the kocho products could also be preserved for up to six years in an air tight pit. besides, the findings of the current study are in agreement with the previous report by holzapfel (2002). in addition, shekacho people traditionally preserve enset products such as bulla, kocho, eekko and bacco by using different spices such as kefo (sacred-bassilyehabesha), toocho (cymbopogon citratus), shoobbo (lippia adoensis) and duqquushe-waamo (leaf of allium sativum). on the other hand, in all preservation processes, occasionally some parts or the whole products could be spoiled and in those cases the spoiled products may be identified by their color, which turns black with sour taste, unpleasant structure, mushy and pungent smell (berhanu abegaz, 1987a). 3.9. medicinal values of enset it was traditionally proved that some of the enset plant parts and their food products have medicinal values for human being and livestock. for instance, they are applicable to cure broken and fractured bones, joint displacement, swellings, wounds, infectious disease, and diarrhea and recognized to stimulate placental discharge. according to the respondents, the most commonly used enset plants for medicinal purposes include maacaa-dami, shuuri, and noobo types. 3.10. biotic factors against enset productivity it was learned, from the field survey and associated interviews, that enset is attacked occasionally by different types of diseases such as bacterial/fungal wilt (figure 8), animal pests such as insects, mole rats, porcupine, wild pig, enset root mealy bug and monkeys which is similar to the report made by temesgen addis et al. (2008). the findings of the study have further indicated that the female types are more prone to the disease caused by kiino than the male types. apparently, the immediate intervention of this problem may require intensive collaborative research activities by involving professionals from various relevant sectors as it was also described by aritua et al. (2008). according to the respondents, kiino affects the plant at all ages before inflorescence. unlike kiino, all other agents attack both types of enset before and after inflorescence. figure 8: enset plant affected by microbial wilt (locally known as kiino). 4. conclusion and recommendation enset has untapped potentialin ensuring food security in ethiopia. the long years of traditional experiences and practices of the shekacho people in kocho fermentation should be maintained and extended to other enset producing and none producing regions of the country. as part of the outcomes of this study, the large differences observed between the female and male enset types and the kocho products, necessitate further research works related to dna profiling of enset. acknowledgment the authors are thankful to the center for food science and nutrition of the addis ababa university (aau) for providing all the necessary laboratory facilities. most expenses utilized for the field studies were obtained from the international science program (isp) through the project (eth: 04). reference adimasu tsegaye and struik, p. c. 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(2006). benders’ dictionary of nutrition and food technology. 8th edn., wood head publishing, 60. biruk ayenew, ayelign mengesha, tewodros tadesse and elias gebre-mariam. (2012). ensete ventricosum (welw.) cheesman: a cheap and alternative gelling agent for pineapple (ananascomosus var. smooth cayenne) in vitro propagation. journal of microbiology, biotechnology and food science, 2(2), 640–652. brandt, s. a., spring, a., hiebsch, c., mccabe, j.t., endale tabogie, mulugeta diro, gizachew wolde-michael, g., yntiso, g., shigeta, m. and shiferaw tesfaye. (1998). the “tree against hunger”, enset based agricultural systems in ethiopia. online publication by the american association for the advancement of science with awassa agricultural research center, kyoto university, center for african area studies and the university of florida, 11–18. berhanu abegaz. (1987a). kocho fermentation. journal of applied bacteriology, 62(6), 473–477. berhanu abegaz. 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(2004). asteraceae (compositae). in: flora of ethiopia and eritrea, v. 4, part 2; (hedberg, i., friis, ib. and edwards, s., eds.). 259. addis ababa, ethiopia uppsala, sweden. mogessie ashenafi. (2006). a review on the microbiology of indigenous fermented foods and beverages of ethiopia. ethiopian journal of biological sciences, 5(2), 189–245. nune, s. (2008). flora biodiversityassessment in bonga, boginda and mankira forest, kafa, ethiopia. submitted to ppp project, addis ababa, ethiopia: 26. sahlin, p. (1999). fermentation as a method of food processing. lund institute of technology, lund university: 28. smid, e. j. and gorris, l. g. (1999). natural antimicrobials for food preservation. food science and technology, new york, marcel dekker, 285–308. stuart, t. (1986). the history of food preservation. totowa, nj: barnes and noble books, 46. tadese kippe. (2002). five thousand years of sustainablity? a case study on gedeo land use (southern ethiopia). treemail publishers, heelsum, the netherlands, 16–100. tariku hunduma and mogessie ashenafi. (2011). effect of altitude on microbial succession during traditional enset (ensete ventricosum) fermentation. international journal of food, nutrition and public health, 4(1), 39–53. temesgen addis, ferdu azerefegne, blomme, g. and kanaujia, k. (2008). biology of the enset root mealybug cataenococcus ensete and its geographical distribution in southern ethiopia. journal of applied biosciences, 8(1), 251–260. temesgen magule and tesfaye bizuayehu. (2009). management of enset (ensete ventricosum (welw.) cheesman) diversity in wolaita, southern ethiopia: farmers’ knowledge and implications for on-farm conservation, 1–9. temesgen magule, tesfaye, bizuayehu, catellani, m. and pè, m. e. (2014). indigenous knowledge, use and on-farm management of enset (ensete ventricosum (welw.) cheesman) diversity in wolaita, southern ethiopia. journal of ethnobiology and ethnomedicine, 10(41), 1–18. tiruha habte, kebede abegaz, edessa negera. (2013). the microbiology of kocho: an ethiopian traditionally fermented food from enset (ensete ventricosum), international journal of life sciences, 8(1), 7–13. yemane tsehaye and fassil kebebew. (2006). diversity and cultural use of enset (ensete ventricosum (welw.) cheesman) in bonga in-situ conservation site, ethiopia. ethnobotany research and applications, 4, 147–158. 93 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 experimental investigation on nox and smoke emission from crdi diesel engine operated with biodiesel blend varying dwell between main and pre injection ramesh babu nallamothu1,*, anantha kamal nallamothu2, seshu kishan nallamothu3, in niranjan kumar4, bv appa rao4 1 mechanical systems and vehicle engineering department, adama science and technology university, p.o. box: 1888, adama, ethiopia 2 vellore institute of technology, vellore, india. 3 srm institute of science and technology, chennai, india 4 marine engineering department, andhra university, visakhapatnam, india. *corresponding author, e-mail: rbnallamothu@gmail.com, mobile: +251 912234395 abstract reducing nox and smoke simultaneously from diesel engine is a big challenge being faced by the researchers in automotive field. biodiesel produced from non-edible cotton seed oil is found to be a promising eco-friendly renewable alternative fuel to petrodiesel. cotton seed oil biodiesel is produced using transesterification process and characterized for its properties. the blend b20, which is most accepted and does not need any modifications of the engine, is used as fuel. formation of nox is very much dependent on the peak temperature in the combustion chamber. the researchers are trying with different techniques for reducing nox, like dilution using egr, injection of water, retardation of injection timing etc. with the development of crdi systems split and multiple injection strategy attracting the attention of researchers as a promising technique in reducing the nox emissions. in this work, an attempt is made to study the effect of dwell between pilot and main injection in a multiple injection strategy of pilotmain-post injection while retarding main injection. in this multiple injection strategy of three injection pulses the pilot fuel quantity is fixed as 10% of total fuel injected, post injection fuel quantity is fixed as 0.5 mg. the dwell between pilot and main was varied at different main injection timing. the post injection is closely coupled with main injection with a dwell of 3 cad. the main injection timing along with pilot and post was retarded from the recommended 23o btdc in steps of 3 degrees. at all main injection timing the dwell of 10 cad observed to be the best for smoke reduction, whereas 20 cad is better for nox reduction. in overall dwell 10 cad is better for tradeoff between nox and smoke. keywords: biodiesel blend, dwell, pilot injection, post injection, transesterification 1. introduction depletion of fossil fuels due to heavy usage of fossil fuels like gasoline and diesel to meet ever growing energy demand world over became a prime concern of the world at the moment. in addition the environmental degradation caused by the harmful pollutants emitted. mailto:rbnallamothu@gmail.com ramesh babu et al. ejssd, v 5 (2), 2018 94 © adama science & technology university https://ejssd.astu.edu.et by burning of petroleum fuels is also haunting the world. with the growth of the population, the usage of diesel has been increasing in transportation and industrial applications to meet the energy requirements causing the release of tons and tons of dangerous pollutants adding to the atmospheric air. these emissions are the main reasons for the consequences like global warming, acid rains and various ailments of human beings. in an effort to minimize the damage caused to the environment, the global world over imposed a stringent regulations on the emissions from usage of petroleum fuels and other fossil fuels. complying with stringer environmental regulations became a big challenge for industries, automobile manufactures and the researchers in the field. different ways and means are being explored to conserve the conventional fuel resources, reduce the dependence on petroleum fuels and reduce the environmental degradation. one way is to look for biobased alternative fuels like biodiesel, bioethanol etc., which are renewable, ecofriendly and home grown. it gives the solution to the problems like depletion of petroleum resources, environmental damage and dependence on oil importation. another way which is tried with is improvement of combustion process by improving the design of combustion chamber, modifying the fuel injection system etc., which improves the fuel economy, efficiency of combustion process, reduces the greenhouse gases and other harmful emissions. vegetable oils, having features of renewability, biodegradability, ecofriendly etc., are promising replacement for conventional petroleum diesel. higher viscosity is the major drawback of straight vegetable oils which hinder its usage directly in unmodified diesel engines. direct usage of straight vegetable oils may cause deposits in combustion chamber and damages the engine. transesterification process is the wellestablished procedure which can be used to produce biodiesel by bringing down the viscosity. tri-glycerids present in vegetable oil get converted into mono alkyl esters of long chain fatty acids (biodiesel) when vegetable oil reacts with alcohol in the presence of catalyst. glycerine comes out as a byproduct (pankaj et al., 2016). therefore, explorations to find biodiesel are one of the most promising alternative fuels to replace or to reduce dependency on the conventional petroleum-based fuels with multiple environmental advantages and application in compression ignition (ci) engines with no modification. biodiesel is nonexclusive, biodegradable, non flammable, renewable, nontoxic, environment friendly, and similar to diesel fuel (yanuandri et al., 2013). the main advantages of biodiesel include the following: it can be blended with diesel fuel at any proportion; it can be used in a ci engine with no modification; it does not contain any harmful substances; and it produces less harmful emissions to the environment than diesel fuel. biodiesel, popularized as the mono alkyl esters are ramesh babu et al. ejssd, v 5 (2), 2018 95 © adama science & technology university https://ejssd.astu.edu.et derived from triglycerides (vegetable oils or animal fats). transesterification is the most convenient process to convert triglycerides to biodiesel. transesterification process involves a reaction of the triglyceride feedstock with light alcohol in the presence of a catalyst to yield a mixture of mono alkyl esters currently, using hydroxides of sodium or potassium, is the common route for industrial production of biodiesel (atabani et al., 2013). the minimization of fuel consumption and the reduction of emissions have been two driving forces for engine development throughout the last decades. the first objective is in the financial interest of the vehicle owners. the second is imposed by legislation, sometimes also supported by excise reductions or customers’ demands for clean engines. the ongoing emission of nox is a serious persistent environmental problem due to; it plays an important role in the atmospheric ozone destruction and global warming (pushparaj et al., 2013). nox is one of the most important precursors to the photochemical smog. component of smog irritate eyes and throat, stir up asthmatic attacks, decrease visibility and damages plants and materials as well. by dissolving with water vapor nox form acid rain which has direct and indirect effects both on human and plants. an scr (selective catalytic reduction) exhaust gas after treatment system which uses urea solution as a reducing agent has a high nox reduction potential and is a wellknown technique for stationary applications (busca et al., 1998). the idea of using urea scr systems for the reduction of nox emissions in diesel engines is two decades old. since then, many applications have been developed, some of which have reached commercialization (bosch et al., 1988). but, it is still a challenge for researchers. with the recent development of common rail direct injection system, it became possible to reduce nox and other emissions by adopting multiple injection strategy (imarisio et al., 2000; badami et al., 2002). split fuel injection involves reducing splitting the injection as two or more events which can lead to a reduction in the ignition delay in the initial fuel pulse. this leads greater fraction of combustion to occur later in the expansion stroke. as majority of nox occurs during premixed stage, the net amount of nox formed during the split fuel injection is lowered (gao et al., 2001). multiple injections method is found to be very effective at reducing particulate emissions at high load, and combined technique of multiple injections with egr is effective at intermediate and light loads. however, increased particulate emissions due to egr causes increased engine wear due to degradation of lubricant. increased brake specific fuel consumption (bsfc) is another concern. split injection up to 5 splits, are experimented (wang et al., 2007) in combination with egr. in this work b20 was used as fuel, since b20 is mostly accepted and does not need modifications of the engine. ramesh babu et al. ejssd, v 5 (2), 2018 96 © adama science & technology university https://ejssd.astu.edu.et 2. methodology this work is done with the main objective of investigating the effect of multiple injection strategy with varying injection timing and dwell period on harmful emissions from crdi diesel engine fueled with biodiesel blend. the dwell is varied from 10 cad to 20 cad in three steps. cotton seed oil is used for the preparation of biodiesel. biodiesel is prepared using transesterification process. a novel scheme of experiments is adopted in the work to understand the influence of multiple injections by varying different parameters on the emissions from the engine. the used injection strategy is pilot (pre)-main-post. the pilot is fixed at 10% and post fuel quantity is fixed as 0.5 mg/cycle. the following were the steps followed in this work: • extraction of oil from cotton seeds using mechanical press • preparation of biodiesel using tranesterification process. • characterisation of biodiesel • preparation of b20 blend • testing the performance of crdi diesel engine with b20 with multiple injection strategy varying injection timing • comparing the emissions from multiple injection and single injection figure1. cotton seed oil, biodiesel, b20, diesel engine setup the setup consists of single cylinder, four stroke, crdi vcr (variable compression ratio) engine connected to eddy current dynamometer. specification of the crdi engine is given in table 1. it is provided with necessary instruments for combustion pressure, crankangle, airflow, fuel flow, temperatures and load ramesh babu et al. ejssd, v 5 (2), 2018 97 © adama science & technology university https://ejssd.astu.edu.et measurements. these signals are interfaced to computer through high speed data acquisition device. the setup has stand‐alone panel box consisting of air box, twin fuel tank, manometer, fuel measuring unit, transmitters for air and fuel flow measurements, process indicator and piezo powering unit. rotameter are provided for engine cooling water flow measurement. crdi vcr engine works with programmable open ecu for diesel injection, fuel injector, common rail with rail pressure sensor and pressure regulating valve, crank position sensor, fuel pump and wiring harness. the setup enables study of crdi vcr engine performance with programmable ecu at different compression ratios and with different egr. engine performance study includes brake power, indicated power, frictional power, bmep, imep, brake thermal efficiency, indicated thermal efficiency, mechanical efficiency, volumetric efficiency, specific fuel consumption, air fuel ratio, heat balance and combustion analysis. table 1. specification of the crdi engine engine kirloskar, single cylinder, four stroke water cooled, vcr stroke 110 mm bore 87.5 mm capacity 661 cc power 3.5 kw speed 1500 rpm compression ratio 12-18 injection system common rail direct injection with open ecu injection pressure 300 bar dynamometer eddy current dynamometer dynamometer arm length 185 mm a novel scheme of experiments is adopted in the work to understand the influence of multiple injections by varying different parameters on the emissions from the engine. the injection is split into pilot (pre)-main-post. after different trials the quantity of pilot injection is fixed as 10% and post fuel quantity is fixed as 0.5 mg/cycle. the dwell between main and pilot is maintained as 10 degrees. closely coupled post injection is used with 3 degrees after main injection. main injection timing is retarded from recommended injection timing of 23o to 11o btdc. the influence of this retardation on nox emission and smoke is measured. b20p10m20p3 stands for biodiesel blend 20, pilot injection with dwell of 10o, main injection at ramesh babu et al. ejssd, v 5 (2), 2018 98 © adama science & technology university https://ejssd.astu.edu.et 20o and post injection with dwell of 3o. 3. result and discussion 3.1. biodiesel characteristics the properties of prepared cotton seed oil biodiesel is given in table 2. 3.2. nox emission it is observed from the below figures (figure 2 – 5) that with multiple injection the nox emission reduced considerably. from figure 2, it is noted that at m11 the nox emission is reducing as the dwell between pilot and main increasing from 10 cad to 20 cad. there is a maximum reduction of 56.91% with dwell of 20 cad compared to single injection m23. at m14 also similar trend of reducing nox emission with increase in the dwell period. maximum reduction of 49.75% is noted with a dwell of 20cad compared to single injection with a load of 6kg. at m17, figure 4 dwell 10 cad found to be better than others. the maximum reduction in nox emission is 36.20% with a load of 12 kg. it is observed that the effect is equally influential at the load of 9 kg. as the main injection timing is retarded the nox emission observed to be reducing due to reduction in the peak temperatures developed in the combustion chamber. multiple injection strategy is observed to be more effective in reducing nox at part load condition. there is a increment in nox with p10 m23 p3. in overall the dwell of 20 cad is observed to be better for nox reduction. at m17 with single injection it is observed that the peak nox emission is at 50% load. when the injection is split the peak nox point shifted towards higher loads. the dwell of 10 cad is better. table 2. properties of biodiesel (eta laboratories). properties b100 density@15 oc,(gm/cm3 0.8865 kinematics viscosity@40 oc 4.85 flash point, oc 149 fire point, oc 160 cloud point, oc +1 gross calorific value, kj/kg 40,695 cetane number 50.8 copper strip corrosion @ 50oc for 3 hrs not worse than no 1 acid value as mg of koh/gm 0.063 carbon residue 0.041% sulphur 0.0043% ramesh babu et al. ejssd, v 5 (2), 2018 99 © adama science & technology university https://ejssd.astu.edu.et 0 200 400 600 800 1000 1200 1400 0 5 10 15 n o x p p m load kg b20 m23 b20 p10 m14 p3 b20 p15 m14 p3 b20 p20 m14 p3 0 200 400 600 800 1000 1200 1400 0 5 10 15 n o x p p m load kg b20 m23 b20 p10 m17 p3 b20 p15 m17 p3 b20 p20 m17 p3 0 200 400 600 800 1000 1200 1400 0 2 4 6 8 10 12 14 n o x p p m load kg b20 m23 b20 p10 m11 p3 b20 p15 m11 p3 b20 p20 m11 p3 figure 2. nox emission at m11 figure 3. nox emission at m14 figure 4. nox emission at m17 ramesh babu et al. ejssd, v 5 (2), 2018 100 © adama science & technology university https://ejssd.astu.edu.et 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 o p a ci ty % load kg b20 m23 b20 p10 m11 p3 b20 p15 m11 p3 b20 p20 m11 p3 0 200 400 600 800 1000 1200 1400 0 5 10 15 n o x p p m load kg b20 m23 b20 p10 m20 p3 figure 5. nox emission at m20 3.3. opacity from the below figures (figure 6 – 10), it is observed that splitting the fuel injection has considerable effect on smoke emission. maximum reduction of smoke is noted at m14 with dwell of 10 cad with 6 kg load. at this condition the reduction in smoke is 58.93%. the reduction of smoke at m11 with a dwell of 10 cad is 55.32% with load of 6 kg. figure 6. opacity at m11 it is observed that the engine is hesitating at higher load with higher dwells of 15 and 20 cad at m23 and m20. at all main injection timing the dwell of 10 cad observed to be the best. the retardation of multiple injection with main injection retardation from 23° btdc to 11° btdc, smoke emission is considerably effected. smoke opacity reduced gradually up to main injection 14° and then starts increasing with ramesh babu et al. ejssd, v 5 (2), 2018 101 © adama science & technology university https://ejssd.astu.edu.et 0 10 20 30 40 50 60 70 80 90 0 5 10 15 o p a ci ty % load kg b20 m23 b20 p10 m14 p3 b20 p15 m14 p3 b20 p20 m14 p3 0 10 20 30 40 50 60 70 80 90 0 5 10 15 o p a ci ty % load kg b20 m23 b20 p10 m17 p3 b20 p15 m17 p3 b20 p20 m17 p3 0 10 20 30 40 50 60 70 80 90 0 5 10 15 o p a ci ty % load kg b20 m23 b20 p10 m20 p3 further retardation. the reduction is 69.1%, 62.23%, 58.93%, 48.68%, 18.29% with load of 0%, 25%, 50%, 75%, 100% respectively at p10 m14 p3. figure 7. opacity at m14 figure 8. opacity at m17 figure 9. opacity at m20 ramesh babu et al. ejssd, v 5 (2), 2018 102 © adama science & technology university https://ejssd.astu.edu.et 0 10 20 30 40 50 60 70 80 90 0 5 10 15 o p a ci ty % load kg b20 m23 b20 p10 m23 p3 b20 p15 m23 p3 b20 p20 m23 p3 figure 10. opacity at m23 4. conclusion • multiple injection is a good means of having tradeoff between smoke and nox emissions. • retardation of multiple injection up to m11 helped in reducing both nox and smoke. • p10 m11 p3 is better for smoke and nox tradeoff. numerous experiments are required to understand the influence of multiple injection. • at all main injection timing the dwell of 10 cad observed to be the best for smoke reduction, whereas 20 cad is better for nox reduction. in overall dwell 10 cad is better for tradeoff between nox and smoke. • further combustion related analysis is required to understand completely the influence of multiple injection • multiple injection strategy seems to be more efficient than conventional in reducing emission due to their capability in controlling heat release rate and hence peak temperature. multiple injection is better than single injection in optimizing tradeoff between nox and smoke due to their efficiency in reducing initial high temperatures and supporting combustion of late injection. • reduction in emissions was improved with multiple pre-mainpost injection strategy, as pre injection supports main injection combustion and reduced delay while post combustion helps in oxidation of soot particles without impact on nox. • proper dwell between injections was significant as small dwell led to situation of single injection while long reduced the effect of pre-mix combustion. for pilot injection dwell around 10 cad reduces emission efficiently. • around 21 cad btdc injection timing of first injection was ramesh babu et al. ejssd, v 5 (2), 2018 103 © adama science & technology university https://ejssd.astu.edu.et observed to be optimum for simultaneous reduction of nox and soot. acknowledgment we are thankful to marine engineering department, andhra university, for giving this opportunity to work on biodiesel applications in diesel engines. we are also thankful to sri venkateswara research center, kanchipuram for providing necessary research facilities. references atabani, a.e., silitonga, a.s., ong, h.c., mahlia, t.m.i., masjuki, h.h., badruddin, i.a., & fayaz, h. (2013). non-ediblevegetable oils: a critical evaluation of oil extraction, fatty acid compositions, biodiesel production, characteristics, engine performance and emissions production, renewable and sustainable energy reviews journal, 18, 211-245. badami, m., millo, f., mallamo, f., and rossi, e. e. (2002). influence of multiple injection strategies on emissions, combustion noise and bsfc of a di common rail diesel engine, sae technical paper 2002-01-0503, https://doi.org/10.4271/2002-01-0503.. bosch, h., & janssen, f.(1988). catalytic reduction of nitrogen oxides: a review on the fundamentals and technology, catalysts today, 2(4), 369 -531. busca g., lietti l., ramis g., and berti f (1998). chemical and mechanistic aspects of the selective catalytic reduction of nox by ammonia over oxide catalysts: a review, applied catalysts b: environmental, 18(2), 1-36 gao, z., & schreiber, w. (2001). the effects of egr and split fuel injection on diesel engine emission, internationaljournal of automotive technology, 2 (4), 123-133. imarisio, r., ricco, m., & sebastiano, g. h. (2000). multiple injection, a cost effective solution for emission reduction of common-rail di diesel engines, aachener kolloquium fahrzeug-und motorentechnik, 9, 1047-1062. shelkea, p.s., sakharea, n.m., lahanea, s. (2016). investigation of combustion characteristics of a cottonseed biodiesel fuelled diesel engine, global colloquium in recent advancement and effectual researches in engineering, science and technology, procedia technology, 25, 1049 1055 perry, r. a., & siebers, d. l. (2013). rapid reduction of nitrogen oxides in exhaust gas streams. nature, 324, 1986, 657–658. pushparaj t, & ramabalan, s. (2013). green fuel design for diesel engine combustion,performance and emission analysis, procedia engineering, 64, 701 – 709 . yanuandri putrasar, arifinnur, aammuharam, (2013). performance and emission characteristic on a two cylinder di diesel engine fuelled with ethanol -diesel blends, procedia, 32. 104 42 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper assessment of bacteriological and physico-chemical quality of drinking water in munesa woreda, arsi zone, oromia, ethiopia morki chilalo gadiso1, tulu degefu2, zerihun belay gemta3,  1department of biology, college of natural and computational science, hawassa university, p. o. box: 05, hawassa, ethiopia 2international crops research institute for the semi-arid tropics, p. o. box 5689, addis ababa, ethiopia 3department of applied biology, school of applied natural science, adama science and technology university, p.o. box , 1888, adama, ethiopia article info abstract article history: received 22 february 2020 received in revised form 28 april 2020 accepted 20 may 2020 potable and accessible household drinking water is essential means of improving communities’ health both in urban and rural areas. the potability of drinking water is affected by bacteriological and physico-chemical parameters. thus, cross-sectional study was conducted during september 2015 to june 2016 to assess the bacteriological and physico-chemical quality of drinking water sources in munesa woreda, arsi zone, oromia, ethiopia. in total sixty four samples from four different water sources were sampled. water samples of tap water, protected boreholes, protected springs and household from different sites were collected. the total coliform, fecal coliform, temperature, ph and total dissolved solids were analyzed based on the standard methods prescribed by apha (2017). the mean counts of total coliform were in the range of 3±2.36 to 30±5.01 (cfu/100 ml) whereas, the mean counts of fecal coliform were found to be 2±1.93 to 22±2.74 (cfu/100 ml). the total and fecal coliforms counts in all water samples were above the recommended limit set by who and ethiopian standard for drinking water quality. however, the results of physico-chemical parameters tested in relation to temperature, ph and tds were observed within the permissible ranges of national and international standards. the presence of fecal coliforms in the water samples demonstrates the presence of pathogenic organisms that would be a threat to anyone consuming the water. thus, it can be suggested that regular monitoring of drinking water sources and hygiene promotion programs can improve quality of drinking water in the study area. keywords: drinking water fecal coliform munesa bacteriological quality total coliform 1. introduction the availability of adequate and quality household drinking water is essential means of improving communities’ health both in urban and rural areas (who, 2011). the rationale for promoting safe drinking water in rural and urban communities in developing countries is the persistently high level of morbidity and mortality (who/unecef, 2017). worldwide, in (2016), 1.9 million deaths and 123 million disability-adjusted life-years (dalys) have  corresponding author, e-mail: zebelay2009@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.207 been registered related to water, sanitation, hygiene and health (who, 2019). the lack of access to water also limits sanitation and hygiene practices in many households because of the priority given for drinking and cooking purposes. only one out of three people using safely managed drinking water services (1.9 billion) lived in rural areas (who/unecef, 2017). http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx morki chilalo et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 43 it is evident that people who are most vulnerable to water-borne diseases are those who use polluted drinking water sources from rivers, streams and hand dug wells. since these sources are open, they are susceptible to animals, birds and human contamination. an estimated 2 billion people drink water that is faecally contaminated, 4.5 billion people use a sanitation system that does not adequately protect their family (who, 2019). ethiopia is one of the countries in the world with water quality problems. it has one of the lowest coverage in sub-saharan countries with 57 % and 28 % for improved drinking water supply and improved sanitation, respectively (unicef and who, 2015). since the traditional water source users are highly vulnerable to water borne diseases, there is a need to check the drinking water regularly to provide measures capable of diminishing the outbreak of water related diseases. communities’ perception of quality also carries great weight in their drinking water safety (doria, 2010). the quality of drinking water is assessed by monitoring non-pathogenic bacteria of fecal origin (fecal indictor bacteria). fecal coliform and total coliform comprise several genera, including escherichia, klebsiella, enterobacter, citrobacter, serratia and hafnia belong to the family enterobacteriaceae. these are functionally-related group of bacteria which have been used to indicate the general quality of drinking water although different types of pathogens can contaminate water, food, air and other environmental media in many ways (stevens et al., 2003; ashbolt, 2004). besides to bacteriological quality, the chemical quality of the drinking water have received particular attention because of their strong toxicity effect at high level of concentration. the major problems of the study area is population growth, expansion of settlements, shortage of potable drinking water access and supply coverage, environmental management, uncontrolled liquid and solid waste disposal (doria, 2010). there was no previous study conducted in this study area regarding to the bacteriological and physico-chemical quality of drinking water from different sources. however, studies have been conducted in several rural and urban areas of the country. several studies carried out in ethiopia on the bacteriological and physico-chemical quality assessment of drinking water (atnafu melaku, 2006; tsega et al., 2013; debasu damtie et al., 2014; mohammed yasin et al., 2015; gonfa duressa et al., 2019). these reports revealed that the bacteriological and physico-chemical parameters of the different water sources had values beyond the maximum limit of who and ethiopian recommendation. they suggested the need for the appropriate intervention including awareness creation and improving of existing infrastructure. therefore, this study was aimed to determine bacteriological and physico-chemical contamination of drinking water from different water sources (protected springs, protected boreholes, household water and tap water) in the residents of the munesa woreda, arsi zone, ethiopia. 2. materials and methods 2.1. description of the study area the study was conducted in munesa woreda, arsi zone, oromia regional state, ethiopia, located at 232 km south of the capital city addis ababa and 57 km south of asella. it is bounded on the south and west by the west arsi zone and lake langano, on the northwest by ziway dugda, on the north by tiyo, on the northeast by digeluna tijo, and on the east by bekoji. the administrative center of the woreda is kersa (figure 1). according to the csa (2007) report, the total population of munesa is estimated to 207,944 having an increment of 28.8% from the 1994 census. the population density is estimated 142.6 people per square kilo meter which is greater than the zone average of 132.2. about 90.95% of the total populations are rural residents. according to the district water supply documentation, the district has 32 rural and 6 urban kebeles having about 23,111 housing units of which 2,092 urban and 21,019 rural households showing 1:8.9 ratio of housing unit to population. about 69% of the urban population receives water from improved sources. 62% of rural population is covered by improved water supply system. in the district, there are 185 water points of which 92 springs on spot (sos), 5 hands dug wells (hdw), 22 springs with distribution system (swds) and 66 water extensions constructed by government and respective projects (district water office documentation). morki chilalo et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 44 figure 1: study area map 2.2. study design and water sample collection a cross sectional prospective study was conducted in monesa woreda during september 2015 to june 2016. a total of 64 water samples from five sites; heban lakicha, chefa, ego town, heban dubo and kersa were collected. purposive sampling techniques were used to include house hold water and all types of water sources used by the community. the set of water samples taken were as follows: 23 samples from household water; 18 from tap water; 18 from protected spring water and 5 from protected borehole water. triplicate samples in 100 ml polyethylene bottles were collected, labeled and then transported in ice-box to asella water supply and sewerage enterprise (awsse) for bacteriological and physico-chemical quality analysis. sampling and preservation techniques were based on the standard method of water sampling and preservation techniques (apha, 2017). 2.3. microbial analysis the samples were analyzed for total coliform (tc) and fecal coliforms (fc) using the membrane filter technique as outlined by the apha (2017). hundred milliliter of water samples were placed on surface of sterile filter membrane with pore size 0.45μm after vigorous shaking and placed on funnel unit of the membrane filter support assembly. the filtration was facilitated by applying a vacuum pump and the assembly was rinsed by sterile dilute water (apha, 2017). up on completion of the filtration process, the bacteria remained on the filter papers were placed on petri dishes containing eosin methylene blue (emb) agar. emb agar contains lactose, sucrose and dyes; eosin and methylene blue as indicators. finally, the cultures were incubated at 37°c for 18 to 24 hrs and at 44.5°c for 24 to 48 hrs for total coliforms and fecal coliforms, respectively. upon completion of incubation period, colonies were observed and the number of colonies formed on the media was reported as colony forming units (cfu) per 100 ml of sample. 2.4. physico-chemical analysis physico-chemical parameters such as ph, total dissolved solids (tds) and temperature were analyzed based on the standard methods prescribed by apha (2017). accordingly, well-mixed 100 ml of samples were filtered through a filter paper in a weighed dry morki chilalo et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 45 glass beaker. the beaker was placed in a drying oven (evaporating dish) maintained at 103°c for 24 hrs. after 24 hrs, the beaker was transferred from drying oven to a desiccator to cool sample for three hours and the beaker was reweighted. the weight of the dried residue was found by subtracting the initial weight from the weight of beaker with the dried residue. finally, the total dissolved solids were calculated. temperature of water samples was determined in the field due to their unstable nature. a thermometer calibrated to 0°c to 100°c was used for temperature measurements. thermometer was immersed in the water sample until the liquid column in the thermometer stops moving for 3 min and the reading was recorded. the ph of the water samples was recorded at the time of sampling by using pocket digital ph meter (apha, 2017). 2.5. data analysis data were entered and analyzed using spss statistical software (version 16). descriptive analysis was made for categorical variables while mean and standard deviation were calculated for continuous variables. results of mean microbial counts and physico-chemical analysis of the water samples were compared with the set standards (who, 2011) and interpreted as acceptable or unacceptable. analysis of variance (anova) at 95% level of significance was used to compare the quality of drinking water among all sites. 3. results in total 64 water samples were analyzed for total coliform (tc) and fecal coliforms (fc) count. the result of microbial analysis indicated that water sources from all sites including heban dubo, heban lakicha, chefa, ego and kersa were found to be positive for total coliforms and fecal coliform (table 1). the mean total coliform counts were ranging from 3±2.36 to 30±5.01 (cfu/100 ml) with the lowest and the highest range corresponding to the total coliform counts from samples of ego (tw) and lakicha (pbhw), respectively. the mean fecal coliform counts were ranging from 2±1.93 to 22± 2.74 (cfu/100 ml) with the lowest and the highest range corresponding to samples from kersa and ego (tw) each and dubo (hhw), respectively (table 1). the total and fecal coliform counts from ego hhw samples were the least and lakicha and dubo hhw samples were the highest for total and fecal coliform in cfu/100 ml, respectively. table 1: bacteriological analysis of water samples in each site site water sample n tc (cfu/100 ml) fc (cfu/100 ml) chefa hhw tw 6 6 10±2.82 8±2.82 5±1.97 5±1.93 dubo hhw pbhw psw 3 3 9 25±4.09 21±4.09 15±2.36 22± 2.74 10±2.74 8±1.58 ego hhw tw 6 6 4±2.60 3±2.36 3±1.93 2±1.93 kersa hhw tw 6 6 6 ±2.89 5±2.89 4±1.93 2±1.93 lakicha hhw pbhw psw 2 2 9 28±5.01 30 ±5.01 13±2.36 20 ±3.35 13±3.35 7±1.58 who (2011) 0 0 ethiopian cse-58 0 0 cse=compulsory ethiopian standard, hhw= household water, tw= tap water, pbh= protected borehole, psw= protected spring water, who= world health organization, tc= total coliform and fc= fecal coliforms. with regard to total coliform count of tw the maximum (8±2.82 cfu/100 ml) and the minimum (3±2.36 cfu/100 ml) was recorded from chefa and ego site, respectively. with respect to fecal coliform count from tw samples chefa was the highest (5±1.93 cfu/100 ml) and ego and kersa were the lowest (2±1.93 cfu/100 ml) (table1). in this study, significant differences within and among water samples was detected for the tc and fc (p< 0.05; table 3). selected physico-chemical parameters of water samples from all sites were analyzed. the mean temperature, ph and tds tests were done for house hold water, tap water, protected borehole and protected spring water sample (table 2). the mean temperature of the water samples were ranging from 13.50±1.00°c to 16.00±0.81°c with low and high range corresponding to temperature of samples from lakicha and dubo hhw, respectively. it is shown that temperature values of all water samples met national and who guidelines for drinking water. the mean ph value of water samples were ranging from 6.61±0.37 to 7.54±0.37. the low (6.61±0.37) and high (7.54±0.37) mean ph value was found from the water samples of lakicha protected borehole and morki chilalo et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 46 household, respectively. all ph values of water samples met national and who criteria for drinking water. the mean concentrations of total dissolved solids were ranging between 525.00±27.63 to 583.00±15.95 (mg/l) for lakicha protected boreholes and ego tap water, respectively (table 2). the minimum mean concentrations of total dissolved solids were recorded in protected borehole water; whereas maximum was observed in tap water sample. in this study, no significant differences within and among water samples was detected for the temperature, ph and tds values (p> 0.05; table 3). table 2: phyico-chemical parameters of treated water samples in each site site water sample n temp. (°c) ph tds (mg/l) chefa hhw tw 6 6 15.58±0.57 14.83± 0.57 7.13± 0.21 7.51± 0.21 574.00 ± 15.95 568.00± 15.95 dubo hhw pbh psw 3 3 9 16.00± 0.81 14.50± 0.81 14.00± 0.47 7.13± 0.30 7.18± 0.30 7.25± 0.17 531.00± 22.56 559.66± 22.56 532.66± 13.02 ego hhw tw 6 6 15.10± 0.57 14.33± 0.57 7.37± 0.21 7.41± 0.21 551.66± 15.95 583.00±15.95 kersa hhw tw 6 6 14.60± 0.57 13.96± 0.57 7.40± 0.21 7.53± 0.21 546.50± 15.95 571.66± 15.95 lakicha hhw pbh psw 2 2 9 13.50± 1.00 14.50± 1.00 14.72± 0.47 7.54± 0.37 6.61± 0.37 7.23± 0.17 556.00± 27.63 525.00± 27.63 555.77± 13.02 who (2011) not exceed 15 6.5 8.5 500 – 1000 ethiopian cse-58 not exceed 15 6.5 8.5 500 – 1000 cse=compulsory ethiopian standard, pbh = protected borehole water, psw = protected spring water, hh = household water, tw = tap water table 3: comparison results of one way analysis of variance (anova) test among and within different drinking water samples at 95% confidence level parameters comparison sum of squares df mean square fcal p-value tc between groups 1685.309 3 561.770 7.539 0.000 within groups 4470.800 60 74.513 total 6156.109 63 fc between groups 356.809 3 118.936 2.917 0.041 within groups 2446.550 60 40.776 total 2803.359 63 temp between groups 8.067 3 2.689 1.388 0.255 within groups 116.213 60 1.937 total 124.280 63 ph between groups 1.258 3 0.419 1.636 0.190 within groups 15.374 60 0.256 total 16.632 63 tds between groups 9207.444 3 3069.148 2.085 0.112 within groups 88327.493 60 1472.125 total 97534.938 63 df= degree of freedom, significant at p<0.05 morki chilalo et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 47 4. discussion the result of bacteriological quality of water sources in this study indicated that all samples were heavily contaminated with both total and fecal coliform and exceeded the standard requirements set by who and ethiopian standard guidelines for drinking water quality (esdwq, 2002; who, 2011). the patterns of total and fecal coliform counts reflected in the water samples shows fecal pollution due to the presence of high human activities and unhygienic practices in the area. in this study, the total coliform and fecal coliform counts were higher in household water samples compared to the tap water (p = 0.000). similarly, other study conducted in bahir dar city, ethiopia indicated that more number of coliform counts in household water than tap water (milkiyas tabor et al., 2011). besides, a country report on the rapid assessment of drinking-water quality in ethiopia by who & unicef (2010) showed higher counts of total coliform in household water compared to tap water. the results show that household water are affected by post-source contamination during transportation and after storage at home and serious attention must be given to quality of household water especially for water stored in household containers. the high level of total and fecal coliform counts recorded in protected borehole water and protected spring water in lakicha and dubo water samples may be attributed to the high degree of contamination of the water sources by fecal matters due to herds of cattle and sheep grazing around the water sources and the pollutants being washed to the protected borehole and protected spring water. likewise, a study in jimma zone, southwest ethiopia by mohammed yasin et al. (2015) showed that total coliform counts of 33 and 30.6 cfu/100 ml, but fecal coliform counts of 6 and 3.4 cfu/100 ml, in protected wells and protected springs, respectively. other study by mengesha admassu et al. (2004) in north gondar also revealed total and fecal coliform counts were above the permissible limits for drinking water. they demonstrated that out of seventy analyzed protected springs and protected well water samples, 71.43% and 28.6% had all kind of indicator bacteria and fecal coliform, respectively. the authors also confirmed that 50% of the samples had a coliform count of 180 per 100ml and the lowest coliform counts was 13 per 100 ml. similar study in southern wollo, ethiopia by atnafu melaku (2006) demonstrated that, 75% of the samples from protected springs were contaminated with total coliforms. this could be explained by luck of water treatment facilities in rural area of the country. in addition to this, public owned water facilities might not have maintenance and follow-up treatment unlike urban once. contrary to this, a study done in bishoftu by desta kassa (2009) indicated that the water samples contaminated by total coliforms number was very small compared with this study ranging between 1-4 coliforms/100 ml which is within the acceptable limit (1-10 coliform/100 ml) set by who (2011). the possible source of variation for the bacteriological contamination of drinking water in different areas is commonly due to differences in water treatment facilities, household sanitation, management of water sources and environmental sanitation. according to onemano and otun (2008), the source of water contamination by microbes may be due to the long term usage of boreholes, springs and tap water. these may lead to deterioration of the water quality because of the pipeline may become corroded with random cracks and in most cases clogged with sediment that will allow the passage of inorganic substances and bacteria. crop cultivation around the water sources, linkage of latrine with drainage systems, the defecation on open areas which could seep slowly into underground water and flows towards gullies and streams as it was highly exposed to waste material. all these factors might be possible reasons for the high total and fecal coliform in the study area. in this study, no significant variation of temperature observed among the tested water samples. the mean temperature of the water samples were ranging from 13.50±1.00°c to 16.00±0.81°c. nearly all water samples collected from household sources were found to be higher in temperature than other sources. a temperature recorded in water sample from dubo household was observed to be 16°c which is above the limit of ethiopian standards for drinking water quality guidelines (esdwq, 2002) and world health organization (who, 2011). contrary to this study, the average temperature of water samples recorded in rural community of ethiopia was 22.71°c (tsega et al., 2013) and in jimma zone, morki chilalo et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 48 southwest ethiopia was maximum temperature (25.8°c) and minimum (20.1°c) (mohammed yasin et al., 2015). the variation in the temperature of the samples might be attributed to difference in sampling locations and environments. some of the water sources are collected from underground while others were from surface and house hold. temperature is the main factor which affects almost all chemical and biological reactions (delpa et al., 2009). it can influences the ph, dissolved oxygen, redox potential and microbial activity (park et al., 2010). higher temperature can favor the growth of microorganisms and encourage the biofilm formation in the distribution and storages containers which could lead to environmental reservoir for pathogenic microorganism (wingender and flemming, 2011). the ph values of all water samples lies between 6.61± 0.37 and 7.54±0.37 which is slightly alkaline and is in agreement with ph range of ethiopian drinking water quality standards (esdwq, 2002) and who (2011) standards. similarly, the ph value of water samples collected and analyzed from jimma zone, southwest ethiopia were found to be between 5.72 and 8.14 (mohammed yasin et al., 2015). the main contributing factor for different in the ph of the samples could be the physico-chemical nature of the soil of sampling sites. the lowest total dissolved solid (tds) (525.00 mg/l) recorded from lakicha protected boreholes and the highest value (583.00 mg/l) recorded from ego tap water were below the maximum permissible limit (1000 mg/l) recommended by who (2011). mohammed yasin et al. (2015) also reported the lowest total dissolved solid (tds) (116 mg/l) and the highest value (623 mg/l) in jimma zone, southern ethiopia. in contrast, low tds values (50–70 mg/l) were recorded from source to household tap connection in nekemte, oromia, ethiopia (gonfa duressa et al., 2019). it has been reported that drinking water with extremely low concentration of tds may be unacceptable because of its insipid taste whereas, the water with high tds value indicates that water is highly mineralized (who, 2008). water containing high total dissolved solids may cause laxative or constipation effects (sasikaran et al., 2012). high concentration of total dissolved solids may affect persons who are suffering from kidney and heart diseases and the potable water should not contain more than 1000 mg/l of total dissolved solids (sasikaran et al., 2012). 5. conclusions the bacteriological quality of all water samples analyzed in the current study were not comply with/satisfy national or international guidelines set for drinking water. however, the results of physicochemical parameters tested in relation to temperature, ph and tds were observed within the permissible ranges of national and international standards. based on the water quality parameters analyzed, tap water was found to be of less polluted than the other water sources (protected boreholes, protected spring and household waters). in general, the presence of fecal coliforms in the water samples demonstrates the potential presence of pathogenic organisms that would be a threat to anyone consuming the water in the study area. thus, it can be suggested that regular monitoring of drinking water sources and hygiene promotion programs can improve quality of drinking water in the study area. acknowledgment the authors are grateful to hawassa university for the financial support of the research project. we are also thankful to asella water supply & sewerage enterprise office for laboratory space and necessary chemicals and equipment support for water quality analysis. reference apha (2017). standard methods for the examination of water &waste water. american people health association, 23rd ed., washington dc. ashbolt, n.j. 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(who) geneva, (who/ england/97.8), p245. who/unecef (2017) joint monitoring program report: progress on drinking water, sanitation and hygiene: 2017 update and sdg baselines. geneva: world health organization and united nations children’s fund. wingender, j. and flemming, h. (2011). biofilms in drinking water and their role as reservoir for pathogens. international journal of hygiene and environmental health, 214(6): 417423. https://www.sciencedirect.com/science/journal/01604120 http://dx.doi.org/10.1016/j.envint.2009.10.008 http://dx.doi.org/10.1016/j.envint.2009.10.008 http://dx.doi.org/10.1016/j.ijheh.2011.05.009 79 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper combination of organic and inorganic fertilizer to improves tef (eragrostis tef) yield and yield components and soil properties on nitisols, in the central highlands of ethiopia girma chala  ethiopian institute of agricultural research, eiar, p.o. box 2003, addis ababa, ethiopia article info abstract keywords: compost farm yard manure nitrogen phosphorus tef a field experiment was made to evaluate combination of organic and inorganic fertilizers on yield and yield components of tef and soil properties. the study was conducted for three consecutive cropping seasons (2015-2017) on farmers’ fields in welmera district of oromiya regional state. the objective of this study was to evaluate the response of organic and inorganic nutrient source on growth and yield of tef under balanced fertilizers. the treatments included eleven selected combinations of organic and inorganic nutrient sources (farm yard manure, compost, nitrogen and phosphorus). the design was randomized complete block with three replications. results revealed that tef yield and yield components were significantly affected by the application of organic and inorganic fertilizer sources. the highest tef grain yield (2042.6 kgha-1) was obtained from the applications of 25% compost with 75% recommended nitrogen and phosphorus fertilizer. while, highest biomass yield (8535.4 kgha-1) was obtained from the applications of full doses of recommended n and phosphorus fertilizers. application of the different organic fertilizers improves the organic matter, total n, available p and ph of the soil in the study area. the result also showed that the highest marginal rate of return was obtained from application of 50% fym (farm yard manure) + 50% recommended nitrogen and phosphorus fertilizer, which is economically the most feasible alternative for tef production on nitisols of central ethiopian highlands. therefore, based on the mmr application of 50% fym (farm yard manure) + 50% recommended nitrogen and phosphorus fertilizer can be recommended for tef production for the study areas. 1. introduction cereals are an important dietary protein and energy source throughout the world (bos et al., 2005). tef is grown as important cereal in ethiopia (abeba, 2009). it is national obsession and is grown by an estimated 6.3 million farmers (claire et al., 2014). it has also recently been receiving global attention particularly as a ‘health food’ due to the absence of gluten and gluten-like proteins in its grains (spaenji et al., 2005). tef has significantly highest share in ethiopia in area of production and it was reported that tef covered 27.02%  corresponding author, e-mail: chalagirma4@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.145 of the total area under cereal production followed by maize 17.3% (csa, 2017/18). tef performs well at an altitude of 1800-2100 mater above sea level annual rainfall of 750-1100 mm, a temperature of 10°c-27°c it can adapt wide range of agro-climatic conditions (ketema, 1993). moderately fertile clay and clay loam soils are ideal for tef. it can also withstand moderate water logged conditions (national soil service, 1994). regardless of its wider adaptation, productivity of tef is low in the country with http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v7.i1.2020.145 girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 80 the national average grain yield of 1.65 tons ha-1 (csa, 2017/18). this is mainly because of low soil fertility (negassa et al., 2013) and severe organic matter depletion (ifpri, 2010) aggravated by low rate of chemical fertilizer application. the rate of chemical fertilizer application is low in the country due to unaffordable price for resource-poor smallholder farmers (endale, 2011). the continued use of chemical fertilizers is also not recommendable as it causes for health and environmental hazards such as ground and surface water pollution by nitrate leaching (pimentel d., 1996). one of the possible options to make use of low rate of chemical fertilizer application without nutrient deficiency of the soil could be recycling of organic wastes. but it is also difficult to attain sustainable productivity either by inorganic fertilizers or organic sources alone (godara, 2012). the best remedy for soil fertility management is, therefore, a combination of both inorganic and organic fertilizers, where the inorganic fertilizer provides nutrients and the organic fertilizer mainly increases soil organic matter and improves soil structure and buffering capacity of the soil (godara, 2012). the combined application of inorganic and organic fertilizers is also widely recognized as a way of increasing yield and improving productivity of the soil sustainably (mahajan et al., 2008). nutrient management has major role to play in obtaining higher productivity and sustainable production of crops cannot be maintained by using chemical fertilizers alone, because of deterioration in soil physical and biological environments (khan et al., 2008). several researchers (singh et al., 2001) have demonstrated the beneficial effect of integrated nutrient management in mitigating the deficiency of many secondary and micronutrients. there are also some research reports in ethiopia that revealed the combined effect of organic (vermicompost, compost and manure) and chemical (np) fertilizer enhanced the yield of tef and reduced the amount of recommended chemical fertilizer by half (girma et al., 2017). similarly, effect of organic sources (compost and manure) and chemical (np) fertilizer enhanced the yield of teff and reduced the amount of recommended chemical fertilizer by half (kassahun et al., 2012 and agegnehu et al., 2014) though there is a huge variation in crop response to different np fertilizer rates, 64/46 n/p2o5 kgha-1 was given by ministry of agriculture and rural development as national blanket recommendation (yadeta et al., 2012). farmers in ethiopia have also awareness about compost and have been preparing and using huge amount especially in central highlands of ethiopia (personal comminution). however, there is little information about the rate of application of compost and chemical fertilizer in the study area either to apply in sole or in combination. this work, therefore, aimed to determining the effect of organic and inorganic fertilizers and their combinations on the yield and yield components of tef. 2. materials and methods 2.1. experimental site the experiment was conducted in the district of welmera and ejere, west shewa zone of oromia national regional state for three consecutive cropping seasons (2015, 2016 and 2017). the experiment site is located at 090 03′ n latitude and 380 30′ e longitude and altitude 2400 meter above sea level for welmera and 090 02′ n and 380 26′ e (figure 1) and an altitude of 2200 meter above sea level for ejere. distance of welmera and ejere 30 and 45 km west of addis ababa respectively. the mean annual rainfall of the study area was 1100mm of which about 85% falls from june to september and the rest from march to may (holeta agricultural research unpublished metrological data). the mean annual temperature is about 14.30c, with the mean maximum and minimum temperatures of 21.70c and 6.90c respectively (figure 2). the major soil types of the trial sites are eutric nitisols (fao-wrb, 2006). the crops widely grown in the study area include wheat (triticum aestivum l.), barley (hordeum vulgare l.), tef (eragrostis tef), faba bean (phaseolus vulgaris l.) and potato (solanum tuberosum l.)(personal communication). 2.2. experimental materials and layout the experimental compost and farm yard was prepared following the standard procedure for compost preparation (suparno et al. 2013). the weight of the compost and farm yard manure was measured for each level at air dried (at 10.5% moisture) bases right before application. the teff variety named kuncho (dz-cr387), which was developed and released by debrezeit girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 81 figure 1: map of the study area 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 jan feb mar apr may jun jul aug sep oct nov dec rf(mm) tem(0c) figure 2: annual rainfall and average mean of temperature in holeta from 2006 to 2017 (source: holeta agricultural research center meteorological report). agricultural research centre in 2006 was used for the experiment. it is a high yielding white-seeded cultivar adapted to a wide range of altitudes. urea (46% n) and dap (18% n and 46% p2o5) were used as a source of nitrogen and phosphorus. the experiment was laid out in randomized complete block design (rcbd) in factorial arrangement and treatments were replicated three times. the trial was carried on permanent plots during the experimental period. the gross plot size was 3 m × 3 m (9 m2) and the net plot size was 2.6m × 2.5 m (6.5 m2). compost was incorporated to the soil on prepared seedbeds twenty one days before planting and chemical fertilizers (np) were applied during planting and seeds were row planted at the rate of 12 kgha-1. all other cultural practices were uniformly applied as per the recommendations. 2.3. treatment combinations t1= negative control t2= recommended np t3= recommended fym based on n equivalency t4= recommended compost based on n equivalency t5= 25% recommended fym based on n equivalency + 75% recommended np girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 82 t6= 50% recommended fym based on n equivalency + 50% recommended np t7= 75% recommended fym based on n equivalency + 25% recommended np t8= 25% recommended compost based on n equivalency + 75% recommended np t9= 50% recommended compost based on n equivalency + 50% recommended np t10=75% recommended compost based on n equivalency + 25% recommended np t11=33% fym +33% compost +33% recommended np samples were collected from well decomposed farmyard manure and compost before they were applied to the field. then their n and p contents were analyzed in the laboratory to determine the rate of application of each treatment, which was based on recommended n equivalent rate for the test crop. the contents of n and p before application in the analyzed samples were 0.88% n and 0.68% p for conventional compost both on 55% dry weight basis and 1.72% n and 0.76% p for farm yard manure on 50% dry weight basis. manure and compost were applied to the field three weeks before sowing and thoroughly mixed in the upper 15 to 20 cm soil depth. nitrogen and p fertilizers were applied in the form of urea and dap respectively. to minimize the loss and increase its efficiency half rate of n was applied as split at planting and the remaining half was side dressed at tillering stage of the crop whereas all p rates were applied as basal application during planting time. the seed was drilled at the recommended seed rate of 15kg/ha in row on 5th, 8th and 6th july of 2015, 2016 and 2017 respectively. to avoid variability came by sowing date, the trial was planted at the same date at both districts because of welmera and ejere districts were classified under similarly agro-ecology and crop planting calendar for both districts from july 1july 12 are the critical time for tef. all recommended agronomic management practices were carried out during the crop growth period as per needed. 2.4. data collection and analysis composite surface soil samples were collected from experimental fields (0-20 cm depth) before treatment application. similarly, soil samples were collected after harvest of the crop from each plot and then composited by replication to obtain one representative sample per treatment. the collected samples were analyzed for the determinations of ph, organic carbon (oc), total n and available p. soil ph was determined with a ph meter from soil: water of 1:1 (w/v) (carter, 1993). organic carbon was determined by the method of walkley and black (1934) and total n using kjeldahl method (jackson, 1958). available p was determined following the procedures of bray and kurtz (1945). collected plant samples include grain yield, above ground total biomass, plant height and panicle length. grain and biomass yield were measured based on plant samples taken from ten central rows (2.6m x 2.5m= 6.5m2), plant height was measured (in cm) by taking five randomly selected plants per plot from the soil surface to the tip of the crop at full maturity stage. grain yield was adjusted to a moisture content of 12.5% before taking sample weight. the agronomic data were subjected to analysis of variance (glm procedure) using sas statistical computer package (sas, 2002). the total variability for each trait was quantified using separate and pooled analysis of variance over years using the following model (gomez and gomoz, 1984): pijk =µ+yi + rj (i) + tk + ty (ik) + eijk where pijk is total observation, µ = grand mean, yi= effect of the ith year, rj (i) is effect of the jth replication (with in the ith year), tk is effect of the kth treatment with ith year ty (ik) is the interaction of kth treatment with ith year and eijk is the random error. duncan multiples range test (dmrt) at 5% probability level was used to detect differences among means. 2.5. economic analysis economic data was collected to assess the costs and benefits associated with different treatments, partial budget, dominance and marginal analyses following technique described by cimmyt (1988). the average yield was adjusted downwards by 10% to reflect the difference between the experimental yield and the expected yield of farmers from the same treatment. this is because, experimental yields even from on-farm experiments under representative conditions, are often higher than the yields that farmers could expect using the same treatments. for calculation the three years average market grain price of teff (etb 20 kg-1), farmgate price of urea and dap fertilizers (etb 11kg-1 and girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 83 13.5 kg-1) respectively. variable cost ratio (vcr) was calculated as a ratio of value of increased crop output to the cost of fertilizer applied. vcr measures the average gain in the value of crop output per kg of fertilizer applied. 3. results and discussion 3.1. effects of combination nutrient use on soil chemical properties mean soil chemical properties such as ph, organic carbon (oc), n and p measured for samples was taken after harvesting. the result showed that higher concentrations of ph, total nitrogen (tn) and organic carbon (oc) were recorded from full dose application of farm yard manure (fym) (table 1). the lowest soil ph, tn, and oc were recorded from the negative control and the highest value of available phosphorus was obtained from full dose of compost. though the values of oc were generally rated as low (jones, 2003), the highest oc, 1.72% was recorded from plots treated with full doses of farm yard manure and the least (1.22%) was from the negative control treatment (table 1). likewise, the total n and available p determined after harvesting is rated medium (tekalign, 1991). as mentioned above for oc, the highest soil total n (0. 26%) was recorded from plots treated with full doses of farm yard manure. the lowest soil n content 0.18% was obtained from negative control treatment as usual. similarly, the highest soil available p (17.2 mg kg-1) was recorded from plots treated with full doses of compost. the highest ph value 5.2 was recorded from full doses of farm yard manure .the average soil ph of the experimental field after harvest was found to be 4.87, which is indicate some improvements but the soil still in acidic range. the lowest soil ph (4.26) was recorded from negative control treatment. similarly, ano and ubochi (2007) reported that application of animal manure and compost increased soil ph. according to murphy (2007) rating, cec content of soil after harvesting was very low (<6), low (6 to 12), medium (12 to 25), high (25 to 40), and very high (>40). the result showed that the cation exchange capacity of study areas was medium (22.8 cmolckg -1). while the highest value of sulfur was obtained from application of full doses of farm yard manure (3.66 ppm). this may due to combination organic and inorganic sources nutrient provides excellent opportunities to overcome all the imbalances besides sustaining soil health and enhancing crop production. according to vanlauwe et al. (2001) the direct interactions between chemical fertilizer and organic matter can improve soil fertility by restocking nutrients lost through leaching and by modifying the ph of the rhizosphere and making unavailable nutrients available. generally, the above results indicate that combination use of organic and inorganic nutrient sources have significant improvement in the overall condition of the soil as well as agricultural productivity if best alternative option is adopted in the tef production area. table 1: physical and chemical soil characteristics (0-20cm depth) of the experimental site after crop harvesting treatments soil physic-chemical properties textural class ph (h2o) tn (%) av.p (ppm) sulfur (ppm) oc (%) cec cmolckg -1 negative clay 4.26 0.18 10.6 2.82 1.22 18.6 rnp clay 4.6 0.20 14.5 2.86 1.61 19.1 fym clay 5.2 0.26 15.4 3.66 1.72 22.8 com clay 5.06 0.24 17.2 2.74 1.64 18.2 25%fym + 75% rnp clay 4.8 0.22 13.6 2.16 1.48 20.4 50%fym + 50% rnp clay 4.9 0.22 14.8 3.08 1.58 18.8 75%fym + 25% rnp clay 5.02 0.25 16.4 3.24 1.66 20.6 25% com + 75% rnp clay 4.8 0.22 15.6 3.28 1.63 19.7 50% com + 50% rnp clay 5.0 0.21 14.2 2.66 1.58 18.5 75%com + 25% rnp clay 4.8 0.23 15.6 3.17 1.62 21.8 33%fym +33% com + 33% rnp clay 5.18 0.24 16.8 2.91 1.64 22.2 ground mean 4.87 0.225 14.97 2.96 1.58 20.06 tn=total; av.p=available phosphorus; oc=organic carbon; cec=cation exchange capacity girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 84 3.2. effects of combination organic and inorganic nutrient on tef yield and yield components the combined analysis of variance over three years showed that the effect of combination organic and inorganic nutrients was highly significant (p<0.01) on grain yield, biomass and day to physiological maturity but significantly affected at (p<0.05) plant height, panicle length and harvest index. the highest grain yield and plant height of tef (2042.6 kg ha-1 and 101.7cm respectively) were obtained from the application of 25% compost and 75% recommended rate of nitrogen and phosphorous. while the highest biomass yield (8535.4kg-1) was obtained from application of full dose of recommended nitrogen and phosphorus. the result of date physiological maturity was high at application of full dose of farm yard manure (146.8) and compost (146.3) and followed by negative control treatment (table 2). the application of 25% compost with 75% recommended n and p has also given comparable grain yield as compared to application of full dose of recommended n and p from inorganic fertilizer. negative control treatment was given the lowest grain and biomass yields under all tested parameters (table 2). therefore, the results of this study has clearly indicated that it is possible to fairly increase tef yield through combined or multiple nutrient application approach, rather than applying nutrient from one source. in line with the current result, research findings of tekalign mamo et al. (2001), getachew agegnehu et al. (2011) and girma et al., (2017) indicated that wheat has showed significance response to the combined soil fertility management treatments containing both organic and inorganic forms under farmers’ field condition that they could be considered as alternative options for sustainable soil and crop productivity in the degraded highlands of ethiopia. the highest (37.9cm) panicle length was recorded from application of 25% fym + 75% rec np, whereas the lowest (29.0cm) panicle length was obtained from negative control treatments. this result is in line with many authors (ejaz et al. 2002; wakene et al., 2014) reported that panicle length of cereals were increase with increasing as np rates increased. harvest index shows the physiological efficiency of plants to convert the fraction of photo-assimilates to grain yield. harvest index was significantly affected at (p< 0.005) to the combination of organic and inorganic nutrient sources, the highest (32.6%) and lowest (23.3%) harvest index was obtained from control treatments and recommended nitrogen and phosphorus respectively. in contrast, a mean hi of about 50% with a positive trend due to increasing nitrogen rate had previously reported in ethiopia (taye et al., 2002). there was substantial variation in harvest index of different from verities to varieties. table 2: effects of organic and inorganic fertilizers application on tef yield and yield components treatments gy(kg/ha) by(kg/ha) ph(cm) pl(cm) dpm hi negative 746.7e 2505.1g 72.9c 29.0c 146.2a 32.6a rec np 1980.4ab 8535.4a 102.0a 36.0ab 137.4d 23.3b fym 1279.1cd 4212.1efg 91.4ab 33.6ab 146.8a 30.9ab compost 1028.1cd 3863.6fg 81.8bc 31.6bc 146.3a 26.8ab 25% fym + 75% rec np 1956.0ab 6358.6bcd 100.8a 37.9a 138.1d 23.8b 50% fym + 50% rec np 1804.7ab 7378.8ab 98.4a 34.9ab 140.1cd 24.6ab 75% fym + 25% rec np 1363.3cd 5717.2bcde 91.8ab 34.6ab 143.7ab 24.1ab 25% comp + 75% rec np 2042.6a 7388.9ab 101.7a 35.0bc 137.4d 27.9ab 50% comp + 50% rec np 1608.40bc 6813.1bc 93.0ab 35.6ab 142.6bc 31.7ab 75% comp + 25% rec np 1323.8cd 5222.2cdef 94.3ab 35.3ab 144.8ab 25.8ab 33% fym + 33% comp + 33% rec np 1319.3cd 4853.5def 90.9ab 34.1ab 144.9ab 27.9ab critical range (cr) 405.5 1707.3 14.3 4.56 3.18 8.65 cv (%) 17.4 19.2 9.9 8.52 1.43 20.4 *, **= significant at p< 0.05 and p< 0.001, respectively; ns= not significant. means in a column with the same letter are not significantly different from each other; gy= grain yield; by= biomass yield; ph= plant height; sl= panicle length; dpm= days physiological maturity, hi= harvest index girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 85 table 3: partial budget and dominance analyses of organic and inorganic fertilizers trial on tef treatments dap (kg/ha) urea (kg/ha) ave gy (kgha-1) adj gy (kgha1) gb (eb ha-1) dap (cost) urea (cost) tcv (eb ha-1) nb(eb ha-1) mrr (%) egative 0 0 746.7 672.0 13440.6 0 0 0 13440.6 fym 0 0 1279.1 1151.2 23023.8 0 0 0 23023.8 compost 0 0 1028.1 925.3 18505.8 0 0 0 18505.8 75% fym + 25% rnp 37.5 32.5 1363.3 1226.9 24539.4 506.3 357.5 863.8 23675.7 598.5 75% comp + 25% rnp 37.5 32.5 1323.8 1191.4 23828.4 506.3 357.5 863.8 22964.7d 33% fym + 33% comp + 33% rnp 50 43.5 1319.3 1187.4 23747.4 675 478.5 1153.5 22593.9d 50% fym + 50% rnp 75 65 1804.7 1624.2 32484.6 1012.5 715 1727.5 30757.1 819.9 50% comp + 50% rnp 100 65 1956 1760.4 35208 1350 715 2065 33143 706.9 25% fym + 75% rnp 100 113.5 1608.4 1447.7 28951.2 1350 1248.5 2598.5 26352.7d 25% com + 75% rnp 100 113.5 2042.6 1838.3 36766.8 1350 1248.5 2598.5 34168.3d rnp 150 130 1980.4 1782.4 35647.2 2025 1430 3455 32192.2d ave gy=average yield; adj gy=adjusted yield; gb= growth benefit; tcv=total cost varies; nb= net benefit; mrr=marginal rate of return. 3.3. economic analysis the economic analysis showed that the application of 50% of farm yard manure plus 50% recommended n and p fertilizers provided the highest marginal rate of the return (mrr) of 819.9% (table 3) suggesting for one birr invested in wheat production, the producer would collect birr 8.19 after recovering his investment. since the mrr assumed in this study was 100%, the treatment with application of 50% of farm yard manure and 50% recommended np gave an acceptable mrr. therefore, the application 50% fym (based on n equivalent rate) and 50% n and p fertilizers mentioned above is found economical to be recommended on nitisols of the study area and similar locations in the central highlands of ethiopia. 4. conclusion the results of three years result were significantly different from each other and the residual effect of the previous year fertilizer application as the plots were fixed during the experimental period. results of soil analysis after harvesting revealed that application of organic fertilizer improved soil ph, oc, total n and available p. based on marginal return rate the use of 50% recommended nitrogen and phosphorus fertilizers from inorganic sources plus 50% farm yard manure based on n equivalent ratio should be recommended for farmers because they were affordable options for increasing soil fertility status and tef yield with improving soil physical and chemical properties in the small-scale farming systems of the study area. hence, combined or multiple use of chemical fertilizer and locally available organic fertilizer application is the best approach for achieving higher fertilizer-use efficiency, maximum yield and economic return of input than the sole application of either of the input types. acknowledgments the authors acknowledge the ethiopian institute of agricultural research (eiar) and would like to express their appreciation to mr. haile beza, mr. beyene offa, mr. tesfaye negash, mrs. kessach birhanu, and mrs. tigist feyisa for their technical assistance during the execution of the experiments under field condition. appreciation is also due for the services of the analytical soil laboratory of holeta agricultural research centre. girma chala . ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 86 reference abeba tadesse (2009). material transfer agreements on teff and vernonia, ethiopian plant genetic resources. journal of politics and law, 2: 77-89. agegnehu getachew, vanbeek c., bird mi (2014) influence of integrated soil fertility management in wheat and teff productivity and soil chemical properties in the highland tropical environment. journal of soil science and plant nutrition, 14: 532545. agegnehu, g., liben, m., molla, a., feyissa, a., bekele, a., getaneh, f., (2011). research achievements in soil fertility management in relation to barley in ethiopia. addis ababa, ethiopia, pp. 137–152. ano a.o. and c.i. ubochi, (2007). neutralization of soil acidity by animal manures; 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journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 experimental investigation on effect of injection timing in multiple injection on nox and smoke from crdi diesel engine fuelled with biodiesel blend ramesh babu nallamothu1,*, anantha kamal nallamothu2, seshu kishan nallamothu3, in niranjan kumar4, bv appa rao4 1 mechanical systems and vehicle engineering department, adama science and technology university, p.o. box: 1888, adama, ethiopia 2 vellore institute of technology, vellore, india. 3 srm institute of science and technology, chennai, india 4 marine engineering department, andhra university, visakhapatnam, india. *corresponding author, e-mail: rbnallamothu@gmail.com, mobile: +251 912234395 abstract diesel engines with their high thermal efficiency and fuel economy are very much successful in commercial applications compared to their counterpart gasoline engines. the emissions like hc and co from diesel engines are less compared to gasoline engines because they run mostly with lean mixtures. but due to heterogeneous combustion nox and smoke emissions from diesel engines is high. due to contradicting requirements for the reduction of nox and smoke, the tradeoff between nox and smoke emission without compromising fuel economy is a big challenge being faced by automotive industries and researchers in the field. biodiesel produced from non-edible feed stock is found to be a good alternative to petro diesel. cotton seed oil biodiesel is produced using transesterification process and characterized for its properties. the blend b20, which is most accepted and does not need any modifications of the engine, is used as fuel. it is observed that the formation of nox is very much dependent on the peak temperature in the combustion chamber. various types of techniques are being tried by the researchers to reduce high nox emission from usage of biodiesel blended fuel in diesel engines. the techniques used are like dilution using egr, injection of water, retardation of injection timing etc. with the development of crdi systems split and multiple injection strategy attracting the attention of researchers as a promising technique in reducing the nox emissions. in this work an attempt is made to study the effect of retardation of injection timing of a selected multiple injection with pilot-mainpost strategy. the selected strategy is with 10% pilot fuel quantity with a dwell of 10 cad and closely coupled fixed quantity of 0.5 mg post injection with 3 cad after main injection. the main injection timing along with pilot and post was retarded from the recommended 23° btdc in steps of 3 degrees. it is observed that the combination of multiple injection and retardation of injection reduced nox emissions effectively without compromising power output and thermal efficieny. keywords: biodiesel blend, emission, pilot injection, post injection, transesterification mailto:rbnallamothu@gmail.com ramesh babu et al. ejssd, v 5 (2), 2018 106 © adama science & technology university https://ejssd.astu.edu.et 1. introduction recently, the extinction issue of fossil fuel due to continuous usage become the focus attention for all of people in the world who depend on this energy source in every of their activity. the people attention is also increasingly focused on fossil fuel due to the fact that continuous usage of this fuel believed causes environmental problem i.e. air pollution and global warming. fossil fuels reservoirs around the world are declining due to their non-renewable nature. at the same time the demand for energy is, continuously, increasing to meet the needs of the world population, which is growing significantly. global warming is being caused by the greenhouse gas emissions. reducing the dependence on fossil fuels will be beneficial, from environmental point of view, since this will reduce the concentration of carbon dioxide in the atmosphere. hence, currently the world has been tried to look for a solution by exploring and using an alternative fuel which is renewable, environmental friendly, sustainable availability and economically feasible sources of energy have emerged as a priority for research to resolve all these problems (putrasar et al., 2013). therefore, explorations to find biodiesel are one of the most promising alternative fuels to replace or to reduce dependency on the conventional petroleum-based fuels with multiple environmental advantages and application in compression ignition (ci) engines with no modification. biodiesel is nonexclusive, biodegradable, non flammable, renewable, nontoxic, environment friendly, and similar to diesel fuel (atabani et al., 2013).the main advantages of biodiesel include the following: it can be blended with diesel fuel at any proportion; it can be used in a ci engine with no modification; it does not contain any harmful substances; and it produces less harmful emissions to the environment than diesel fuel. biodiesel, popularized as the mono alkyl esters are derived from triglycerides (vegetable oils or animal fats).transesterification is the most convenient process to convert triglycerides to biodiesel. transesterification process involves a reaction of the triglyceride feedstock with light alcohol in the presence of a catalyst to yield a mixture of mono alkyl esters currently, using hydroxides of sodium or potassium, is the common route for industrial production of biodiesel (pushparaj et al., 2013). the minimization of fuel consumption and the reduction of emissions have been two driving forces for engine development throughout the last decades. the first objective is in the financial interest of the vehicle owners. the second is imposed by legislation, sometimes also supported by excise reductions or customers’ demands for clean engines. the ongoing emission of nox is a serious persistent environmental problem due to; it plays an important role in the atmospheric ozone destruction and global warming (busca et al., 1998). nox is one of the most important precursors to the photochemical smog. ramesh babu et al. ejssd, v 5 (2), 2018 107 © adama science & technology university https://ejssd.astu.edu.et component of smog irritate eyes and throat, stir up asthmatic attacks, decrease visibility and damages plants and materials as well. by dissolving with water vapor nox form acid rain which has direct and indirect effects both on human and plants. an scr (selective catalytic reduction) exhaust gas after treatment system which uses urea solution as a reducing agent has a high nox reduction potential and is a wellknown technique for stationary applications (bosch et al., 1988). the idea of using urea scr systems for the reduction of nox emissions in diesel engines is two decades old. since then, many applications have been developed, some of which have reached commercialization (perry et al., 2013). but, it is still a challenge for researchers. with the recent development of common rail direct injection system, it became possible to reduce nox and other emissions by adopting multiple injection strategy (imarisio et al., 2000; badami et al., 2002). split fuel injection involves reducing splitting the injection as two or more events which can lead to a reduction in the ignition delay in the initial fuel pulse. this leads greater fraction of combustion to occur later in the expansion stroke. as majority of nox occurs during premixed stage, the net amount of nox formed during the split fuel injection is lowered (gao et al., 2001). multiple injections method is found to be very effective at reducing particulate emissions at high load, and combined technique of multiple injections with egr is effective at intermediate and light loads. however, increased particulate emissions due to egr causes increased engine wear due to degradation of lubricant. increased brake specific fuel consumption (bsfc) is another concern. split injection up to 5 splits, are experimented in combination with egr (wang et al., 2007). the injection timing of 35o btdc leads to insufficient combustion causing increase in the level of hc. fuel consumption increases with early injection due to insufficient combustion in the initial combustion duration. introduction of pilot injection reduces the flame temperature reducing the amount of nox emission. when the quantity of pilot injection is increased the level of noise reduces (syed et al., 2015). effects of start of pilot injection, start of main injection and fuel injection pressure on engine performance, emissions and combustion characteristics of karanja biodiesel blends compared to mineral diesel were investigated at 1500 rpm in a single cylinder crdi engine. bsfc of test fuels increased with increasing concentration of karanja biodiesel. lower karanja biodiesel blends showed lower brake specific co and hc emissions in comparison to mineral diesel but bshc emissions of kome50 were higher than mineral diesel at some operating conditions. brake specific nox emissions from kome20 and kome10 were higher than mineral diesel. at different sopi timings and fixed somi timing, bsnox emissions were almost similar for all test fuels. bsnox emissions were higher for 1000 ramesh babu et al. ejssd, v 5 (2), 2018 108 © adama science & technology university https://ejssd.astu.edu.et bar fip in comparison to 500 bar fip. combustion duration of kome50 was higher than mineral diesel due to relatively inferior mixing characteristics and requirement of larger fuel quantity. this experimental investigation shows that utilization of 10% or 20% karanja biodiesel blends in crdi engines with pilot injection can be useful in improving engine efficiency and reducing emissions (atuldhar et al., 2015). for solving the problems like depletion of fossil fuels and environmental degradation, biodiesel usage in diesel engines is widely investigated. the performance of cotton seed oil biodiesel is investigated on a single cylinder cidi engine at a constant speed of 1500 rpm and field compression ratio 0f 17.5 at different load conditions. the performance, combustion and emission parameters are measured and compared with baseline results of diesel fuel. the brake thermal efficiency of cotton seed oil methyl ester (csome) was lower than that of petro diesel and brake specific fuel consumption was found to be higher. however, biodiesel resulted in the reduction of carbon dioxide, un-burnt hydrocarbon, and smoke opacity at the expense of nitrogen oxides. carbon monoxide emissions for biodiesel was higher at maximum output power. it has been found that the combustion characteristics of cotton seed oil methyl ester closely followed those of standard petro diesel. the experimental results suggested that biodiesel derived from cotton seed oil could be used as a good substitute to petro diesel fuel in a conventional diesel without any modification (rao et al., 2014). in this work b20 was used as fuel, since b20 is mostly accepted and does not need in modifications of the engine. 2. methodology this work is done with the main objective of investigating the effect of multiple injection strategy with varying injection timing and dwell period on harmful emissions from crdi diesel engine fueled with biodiesel blend. cotton seed oil is used for the preparation of biodiesel. biodiesel is prepared using transesterification process. a novel scheme of experiments is adopted in the work to understand the influence of multiple injections by varying different parameters on the emissions from the engine. the used injection strategy is pilot (pre)-main-post. the pilot is fixed at 10% and post fuel quantity is fixed as 0.5mg/cycle. the following were the steps followed in this work: • extraction of oil from cotton seeds using mechanical press • preparation of biodiesel using tranesterification process • characterization of biodiesel • preparation of b20 blend • testing the performance of crdi diesel engine with b20 with multiple injection strategy varying injection timing • comparing the emissions from multiple injection and single injection. ramesh babu et al. ejssd, v 5 (2), 2018 109 © adama science & technology university https://ejssd.astu.edu.et engine setup the setup consists of single cylinder, four stroke, crdi vcr (variable compression ratio) engine connected to eddy current dynamometer. specification of the crdi engine is given in table 1. it is provided with necessary instruments for combustion pressure, crank angle, airflow, fuel flow, temperatures and load measurements. these signals are interfaced to computer through high speed data acquisition device. the setup has stand‐alone panel box consisting of air box, twin fuel tank, manometer, fuel measuring unit, transmitters for air and fuel flow measurements, process indicator and piezo powering unit. rotameter are provided for engine cooling water flow measurement. crdi vcr engine works with programmable open ecu for diesel injection, fuel injector, common rail with rail pressure sensor and pressure regulating valve, crank position sensor, fuel pump and wiring harness. the setup enables study of crdi vcr engine performance with programmable ecu at different compression ratios and with different egr. engine performance study includes brake power, indicated power, frictional power, bmep, imep, brake thermal efficiency, indicated thermal efficiency, mechanical efficiency, volumetric efficiency, specific fuel consumption, air fuel ratio, heat balance and combustion analysis. nox is measured using avl digas 444n exhaust gas analyser and smoke is measured using avl 437c smoke meter. a novel scheme of experiments is adopted in the work to understand the influence of multiple injections by varying different parameters on the emissions from the engine. the injection is split into pilot (pre)-main-post. after different trials the quantity of pilot injection is fixed as 10% and post fuel quantity is fixed as 0.5 mg/cycle. the dwell between main and pilot is maintained as 10 degrees. closely coupled post injection is used with 3 degrees after main injection. main injection timing is retarded from recommended injection timing of 23o to 11o btdc. the influence of this retardation on nox emission and smoke is measured. b20p10m20p3 stands for biodiesel blend 20, pilot injection with dwell of 10o, main injection at 20o and post injection with dwell of 3o. table 1. specification of the crdi engine engine kirloskar, single cylinder, four stroke water cooled, vcr stroke 110 mm bore 87.5 mm capacity 661 cc power 3.5 kw speed 1500 rpm compression ratio 12-18 ramesh babu et al. ejssd, v 5 (2), 2018 110 © adama science & technology university https://ejssd.astu.edu.et 0 100 200 300 400 500 600 700 800 900 d m23 b20 m23 b20 p10 m23 p3 b20 p10 m20 p3 b20 p10 m17 p3 b20 p10 m14 p3 b20 p10 m11 p3 n o x p p m 3. result and discussion the properties of prepared cotton seed oil biodiesel is given in table 2. it is observed from the chart (figure 1 to 4) that the nox emission is greatly affected by injection timing. at all loads the selected injection strategy has influence on the nox emission. at part loads the the effect is very much prominent. as the injection timing is retarded the nox emission observed to be reducing due to reduction in the peak temperatures developed in the combustion chamber. the reduction is about 45.93% with 75% load at p10 m11 p3 compared to m23. the reduction is 50.58% with 50% load at p10 m11 p3 compared to m23. splitting the injection at m23 observed to be not beneficial multiple injection strategy is observed to be more effective in reducing nox at part load condition. there is an increment in nox with p10 m23 p3. with b20 the engine was not running smoothly with splitting the injection at m23 and m20. table 2. properties of biodiesel figure 1. nox emission at 25% load properties b100 density@15 oc, ( gm/cm3 ) 0.8865 kinematics viscosity@40 oc 4.85 flash point, oc 149 fire point, oc 160 cloud point, oc +1 gross calorific value, kj/kg 40,695 cetane number 50.8 copper strip corrosion @ 50oc for 3 hrs not worse than no 1 acid value as mgof koh/gm 0.063 carbon residue 0.041% sulphur 0.0043% ramesh babu et al. ejssd, v 5 (2), 2018 111 © adama science & technology university https://ejssd.astu.edu.et 0 200 400 600 800 1000 1200 1400 d m23 b20 m23 b20 p10 m23 p3 b20 p10 m20 p3 b20 p10 m17 p3 b20 p10 m14 p3 b20 p10 m11 p3 n o x e m is si o n in p p m 0 200 400 600 800 1000 1200 1400 d m23 b20 m23 b20 p10 m23 p3 b20 p10 m20 p3 b20 p10 m17 p3 b20 p10 m14 p3 b20 p10 m11 p3 n o x e m is si o n in p p m 0 200 400 600 800 1000 1200 1400 d m23 b20 m23 b20 p10 m23 p3 b20 p10 m20 p3 b20 p10 m17 p3 b20 p10 m14 p3 b20 p10 m11 p3 n o x x e m is si o n in p p m figure 2. nox emission at 50% load figure 3. nox emission at 75% load figure 4. nox emission at 100% load ramesh babu et al. ejssd, v 5 (2), 2018 112 © adama science & technology university https://ejssd.astu.edu.et 0 10 20 30 40 50 60 70 80 90 0 5 10 15 s m o k e % load % d m23 b20 m23 b20 p10 m23 p3 b20 p10 m20 p3 b20 p10 m17 p3 b20 p10 m14 p3 b20 p10 m11 p3 it is observed that the retardation of multiple injection with main injection retardation from 23o btdc to 11o btdc, smoke emission is considerably affected (figure 5). smoke opacity reduced gradually up to main injection 14o and then starts increasing with further retardation. the reduction is 69.1%, 62.23%, 58.93%, 48.68%, and 18.29% with load of 0%, 25%, 50%, 75%, and 100% respectively at p10 m14 p3. reduction in smoke with multiple injections is more at lower loads than higher loads. figure 5. smoke emission with varying load 4. conclusion  retardation of multiple injection up to m11 helped in reducing both nox and smoke. further retardation caused increment in smoke.  b20p10m14p3 observed to be better for smoke. smoke starts increasing with further retardation.  nox observed to be reducing continuously with retardation.  p10 m11 p3 is better for smoke and nox tradeoff  multiple injection is a good means of having tradeoff between smoke and nox emissions.  it is a very complex process. numerous experiments are required to have thorough understanding of the influence of multiple injection.  dwell 10 is observed to be better  further combustion related analysis is required to understand completely the influence of multiple injection  multiple injection strategy seems to be more efficient than conventional in reducing emission due to their capability in controlling heat release rate and hence peak temperature.  multiple injection is better than single injection in optimising tradeoff between nox and smoke due to their efficiency in reducing initial high temperatures and supporting combustion of late injection. ramesh babu et al. ejssd, v 5 (2), 2018 113 © adama science & technology university https://ejssd.astu.edu.et  reduction in emissions was improved with multiple pre-main-post injection strategy, as pre injection supports main injection combustion and reduced delay while post combustion helped in oxidation of soot particles without impact on nox.  proper dwell between injections was significant as small dwell led to situation of single injection while long reduced the effect of pre-mix combustion. for pilot injection dwell around 10 cad observed to be better for reducing harmful emission efficiently.  around 21 cad btdc injection timing of first injection was observed to be optimum for simultaneous reduction of nox and soot.  multiple injection strategy is more effective in reducing smoke emissions at lower loads.  the rate of increase in smoke emission is high as load increases with multiple injection strategy. acknowledgment we are thankful to marine engineering department, andhra university, for giving this opportunity to work on biodiesel applications in diesel engines. we are also thankful to sri venkateswara research center, kanchipuram for providing necessary research facilities. reference atuldhar, avinash, k.a. (2015). experimental investigations of the effect of pilot injection on performance, emissions and combustion characteristicsof karanja biodiesel fuelled crdi engine, energy conversion and management, 93, 357– 366. atabani, a.e., silitonga, a.s., ong, h.c., mahlia, t.m.i., masjuki, h.h., badruddin, i.a., & fayaz, h. (2013). non-ediblevegetable oils: a critical evaluation of oil extraction, fatty acid compositions, biodiesel production, characteristics, engine performance and emissions production, renewable and sustainable energy reviews journal, 18, 211-245. badami, m., millo, f., mallamo, f., & rossi, e. e. (2002). influence of multiple injection strategies on emissions, combustion noise and bsfc of a di common rail diesel engine, sae tech. ser., no.2002-01-0503. bosch, h., & janssen, f.(1988). catalytic reduction of nitrogen oxides: a review on the fundamentals and technology, catalysts today, 2(4), 369 -531. busca, g., lietti, l., ramis g., & berti, f. (1998). chemical and mechanistic aspects of the selective catalytic reduction of nox by ammonia over oxide catalysts: a review, applied catalysts b: environmental, 18(2), 1-36 gao, z., & schreiber, w. (2001). the effects of egr and split fuel injection on diesel engine emission, international journal of automotive technology, 2 (4), 123-133. ramesh babu et al. ejssd, v 5 (2), 2018 114 © adama science & technology university https://ejssd.astu.edu.et imarisio, r., ricco, m., & sebastiano, g. h. (2000). multiple injection, a cost effective solution for emission reduction of common-rail di diesel engines, aachener kolloquium fahrzeug-und motorentechnik, 9, 1047-1062. perry, r. a., & siebers, d. l. (2013). rapid reduction of nitrogen oxides in exhaust gas streams. nature, 324, 657–658. pushparaj, t, & ramabalan, s. (2013). green fuel design for diesel engine combustion,performance and emission analysis, procedia engineering, 64, 701 – 709. rao, p.v, & jaedaa abdulhamid (2014). an experimental investigation of petrodiesel and cotton seed biodiesel (csome) in diesel engine, international journal of mechanical and mechatronics engineering, 8 (11). aalam, c.s., & saravanan, c.g. (2015). reduction of nox and noise emissions by pilot injection strategy in crdi diesel engine with the use of central composite design (ccd), international journal of advanced engineering research and science (ijaers), 2 (9), 10-15. wang, d., zhang, c. & wang, y. (2007). a numerical study of multiple fuel injection strategies for nox reduction from di diesel engines, international journal of green energy, 4 (4), 453 – 470. yanuandri putrasar, arifinnur, aammuharam, (2013). performance and emission characteristic on a two cylinder di diesel engine fuelled with ethanol -diesel blends, procedia, 32. 1 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 effect of sintering temperature on the efficiency of clay ceramic water filter enyew amare zereffa* and tegene desalegn adama science and technology university, school of applied natural science, applied chemistry program, p. o. box 1888, adama, ethiopia. * corresponding author, e-mail: enyewama@yahoo.com abstract billion cases of diarrhea occur worldwide each year that result in million deaths because of lack of access to safe drinking water. clean water is a key concern in many communities of developing countries. household water treatment and safe storage methods, such as ceramic water filters, is one of the proven methods and have been shown to reduce diarrheal prevalence. the aim of this work was to develop a ceramic water filter with a better flow rate, which is capable to remove chemicals as well as microbial contaminants, by examining the effect of altering specific design variables. ceramic water filters were developed from 60% of clay, 25% sawdust, and 15% grog by volume and sintered in 800-950°c range at 50°c intervals with 5°c per minute heating and cooling rate for 6 hours. the developed ceramic filters were characterized with fesem, edx, xrd, ph meter, bet and ftir. the better ceramic water filter with total porosity of 32.95 ± 0.03, average pore diameter of 50 nm, flow rate 1.97 ± 0.23% and escherichia coli removal efficiency 99.36 ± 0.55% was developed from 60 % clay; sawdust 25%, 15% grog by volume and sintered at 900°c for 6 hours. keywords: sintering, ceramic filter, escherichia coli, microstructure, porosity 1. introduction safe drinking water is not available to the majority of the people living in the developing countries. clean water is one of the most important public health measures in providing major controls against infectious diseases (unicef /who, 2009 & clasen et al., 2004). filtration, which is one of the proven household water treatment and safe storage methods (hwts) have been shown to reduce diarrheal prevalence by an average of 45% among users (clasen and boisson, 2006). one of the low cost methods of water purification is the use of clay ceramic filters. ceramic water filter is a porous ceramic medium to filter microbes or other contaminants from water. the pore size of the ceramic medium is engineered to trap anything bigger than a water molecule. the investigation of ceramic water filter to remove contaminants and microbes in water processing is becoming more effective and popular among ceramists (zereffa and bekalo, 2017). ceramic filters have been proven mailto:enyewama@yahoo.com enyew amare & tegene desalegn ejssd, v 5 (2), 2018 2 © adama science & technology university https://ejssd.astu.edu.et effective for improving water quality (brown et al., 2007), users and implementers often express concern over their inability to produce a sufficient quantity of water due to their slow flow rate of approximately 1-2 liters per hour. if the flow rate could be increased by altering thecurrent filter design, it would improve the ceramic filter’s viability as a scalable hwts option (erhuanga et al., 2014). water filtration is a process of removing suspended and colloidal particles in water. it is principally concerned with the removal of insoluble impurities, biological or physical. the contaminants are physically prevented from moving through the filter either by screening them out with very small pores and/or, in the case of carbon filters, by trapping them within the filter matrix by attracting them to the surface of carbon particles (the process of adsorption) (ajayi and lamidi, 2015). one of the methods of water purification in this category is the use of ceramic filters (sobsey et al., 2008). these filters may be produced with different materials and in various forms (potter for peace, 2006; hagan et al., 2009). however, the most common ceramic filters are modified fired clay filters, which are supplied in candle, pot and frustum forms. these ceramic filters have become conventional in some parts of the world, such as india and nepal (mintz et al., 1995). the ceramic filter designs developed from 15% saw dust, 80% clay and 5% grog that sintered at 950°c and 1000°c reported with e. coli removal efficiency of 97.50 ± 1.73% and 95.94 ± 1.73% (zereffa and bekalo, 2017). therefore, the aim of the research was to develop a ceramic filter from 60% of clay soil, 25% sawdust and 15% grog that sintered at different temperature for household water treatment that is capable of removing microbial and chemical contaminants from water. 2. methodology the main raw materials used for the production of the filter are clay, water, grog and burnout materials (sawdust). clay soil was collected from kechene, mariam river. kechene woreda is located in addis ababa administrations of gullalle sub-city woreda at 38°45’0”e and 9°3’30”n. each of the basic materials was subjected to various physical treatments before use in the preparation of the filter materials. these treatments include sun drying, crushing and grinding (with piston and mortar), and sieving (using 75 μm sieve size). grinding of the clay, grog, and sawdust to a finer texture was done after the materials had been sun-dried. sieving was performed for all basic materials that is; clay, sawdust, and grog separately to obtain different particle sizes. clay, saw dust and grog were mixed for more than one hour in dry. then, water was added uniformly on a dry mixture of clay, saw dust and grog. the blends were again mixed in wet by wedging and rolling to get a homogenous uniform mixture and the wet mixture was divided into blocks. the blocked clay mixtures were molded in to frustum shape by using a 2-ton car enyew amare & tegene desalegn ejssd, v 5 (2), 2018 3 © adama science & technology university https://ejssd.astu.edu.et jack. the manufactured filter elements were 20 cm top diameter, 15.0 cm height, 10 cm bottom diameter, and 1.10cm wall thickness. the shaped filters were allowed to sundry for about two weeks. once the filters were completely dried they were sintered in muffle furnace at 800, 850, 900 and 950°c temperatures for a period of 6 hours gradually starting from room temperature with an intermediate stay time 1hr at 500°c for combustible material removal in the initial heat treatment. afterward, the filters were left to cool gradually until the temperature reached room temperature. once cooled, the filters were soaked in water for 24 hours and tested for their clean water flux. the selected filters were washed with distilled water, dried in oven, packed properly in plastic bags to protect them from any contamination and made ready for the different tests. each of the filter designs were replicated into 3. the contaminated river water sample was collected in sterilized containers from modjo river, which is found in modjo town by purposive sampling techniques (ilker et al., 2016). modjo river is located 75 km east of addis ababa the capital city of ethiopia which is geographically situated in between 39° 05' e – 39° 4'e longitudes and 8° 34' – 9° n latitudes. to evaluate the performance of each filter, the difference in water quality of influent and effluent water was measured. the quality parameters determined were escherichia coli (e.coil), turbidity, total dissolved solid (tds), conductivity, and ph. membrane filtration was used to determine the e. coli concentration of the influent and effluent samples of the filters. samples were filtered in triplicate through 47 mm diameter and 0.45 μm pore size cellulose ester filters of millipore. influent samples were diluted before filtering through a membrane filter. the membranes were incubated on agar for 16–24 hours at 37°c. the log10 reduction value is used to describe the removal efficiency in case the bacteria removal approaches 100%. the lrv can be calculated with: 𝐿𝑅𝑉 = { 𝑛𝑜. 𝐸. 𝑐𝑜𝑙𝑖 𝐼𝑛𝑓𝑙𝑢𝑒𝑛𝑡 𝑛𝑜. 𝐸. 𝑐𝑜𝑙𝑖 𝐸𝑓𝑓𝑓𝑙𝑢𝑒𝑛𝑡 } 𝑙𝑜𝑔10 flow rates were estimated from the volume of measured filtrate and duration of flow through the filter medium. porosity of the ceramic filters was determined using the water absorption test (direct) method. the filters were washed thoroughly and dried in oven. the dry mass of the filters was measured. the filters were again soaked in distilled water for 24 hours for saturation. the saturated masses of the filters were measured (d'ujanda, 2001). the total porosity (p) of the filter was calculated by the equation (1). porosity of filter = 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑎𝑡𝑢𝑟𝑎𝑡𝑒𝑑 𝑓𝑖𝑙𝑡𝑒𝑟−𝑀𝑎𝑠𝑠 𝑜𝑓 𝑑𝑟𝑦 𝑓𝑖𝑙𝑡𝑒𝑟 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 𝑥 𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑖𝑙𝑡𝑒𝑟 (1) enyew amare & tegene desalegn ejssd, v 5 (2), 2018 4 © adama science & technology university https://ejssd.astu.edu.et table 1: composition of filter design in percentages and sintering temperature. no filter design clay(v/v) grog(v/v) sawdust(v/v) sintering temperature (c) 1 c800-60-25-15 60 15 25 800 2 c850-60-25-15 60 15 25 850 3 c900-60-25-15 60 15 25 900 4 c950-60-25-15 60 15 25 950 3. result and discussion a) chemical analysis table 2 shows the chemical composition of the raw and fired clay ceramic filter. the results revealed that the raw clay essentially consists of si and al. the amount of iron oxide is also noticeable while the contents of alkalis and alkaline-earth elements are low. the significant iron oxide content explains the red color of the raw clay sample. the composition of the fired clay is different from that of the raw clay, characterized by a significant increase of al and si due to the addition of grog (or fired clay without 3burnout). the relative high amount of al2o3 and low content of alkaline oxides, which serve as fluxes, indicate that the clay came from typical kaolinitic clay. the energy dispersive spectrometry (eds) analysis revealed the presence of more elements like copper, tin and carbon in the ceramic filter surface that used for contaminated water analysis as indicated in figure 2. furthermore, the sio2/al2o ratio of 2.03 and 2.45 are above that of 1.18 associated with kaolinite, indicates an excess of sio2 in the form of free quartz. table 2: chemical composition (%) of raw clay and fired clay ceramic filter. item sio2 al2o3 fe2o3 cao mgo na2o k2o mno p2o5 tio2 h2o loi fired 58.1 23.6 8.2 1.4 0.72 2.1 2.7 0.06 0.10 0.4 0.2 2.7 raw 47.3 21.9 11.6 0.4 <0.01 4.2 1.5 <0.01 0.07 0.3 2.2 11.6 loi: loss of ignition figure 2 shows the xrd pattern of the fired ceramic filter. the major peaks are associated with quartz (q) in agreement with the results in table 2. other peaks are related to kaolinite (k) and muscovite mica (m). the presence of enyew amare & tegene desalegn ejssd, v 5 (2), 2018 5 © adama science & technology university https://ejssd.astu.edu.et kaolinite can be attributed to the lowfiring temperature, 600°c. it should be remembered that above this temperature kaolinite transforms to metakaolinite, which is an amorphous material and, consequently, displays no xrd peaks (carty et al., 1998). the porosity of the ceramic filter developed slightly increased with an increase in sintering temperature for the same composition of clay and burnout as it can be seen from the figure 3b. moreover, figure 3b shows that the effect of firing on the porosity of the filter element that sintered at 900°c and 950°c are almost the same. the flow rate through the filters was found to vary with change in sintering temperature. the average flow rate of filter designs: c80050-15-35 (2.16±0.32l/h), c850-60-1525 (2.56±0.24 l/h), c900-60-15-25 (1.97±0.23l/h) & c950-60-15-25 (1.56 ± 0.25) as indicated in table 3 were relatively good as per the potters for peace recommendation (rayner, 2006). filter that sintered at 850°c exhibited the fastest discharge. the flow rate of the ceramic filters was affected by the porosity of the filter elements as indicated on figure 3a. high flow rate, ~ 2.5 l/h, was obtained by low total porosity filter (c850-60-15-25) which might be due to the absence of dead and isolated pores in the filter body. figure 1. eds spectrum of ceramic filter design (c900-60-25-15) after it is used for contaminated water filtration. enyew amare & tegene desalegn ejssd, v 5 (2), 2018 6 © adama science & technology university https://ejssd.astu.edu.et 10 20 30 40 50 60 70 500 600 700 800 900 1000 1100 q m m k q q k in te s it y /p e rc o u n t two theta figure 2a. x-ray diffraction pattern of raw clay. 10 20 30 40 50 60 70 80 0 100 200 300 400 500 600 v m q q m q in te n s it y two theta figure 2b. x-ray diffraction pattern of c900-60-15-25 enyew amare & tegene desalegn ejssd, v 5 (2), 2018 7 © adama science & technology university https://ejssd.astu.edu.et table 3: ceramic filter design with: average flow rate, total porosity, and e coil removal efficiency and other quality parameters. no filter design flow rate (l/hr) porosity (%) e-coil (%) tds (ppm) turbidity (%) e.c., μs ph 1 c800-60-15-25 2.16±0.32 31.07±0.02 98.97±1.22 288 100 138± 0.23 7.4± 0.13 2 c850-60-15-25 2.56±0.24 30.37±0.02 90.33±3.36 261 98.9 101 ± 0.30 7.2± 0.02 3 c900-60-15-25 1.97±0.23 32.95±0.03 99.05±1.79 250 93.5 98 ± 0.38 7.0± 0.01 4 c950-60-15-25 1.56±0.25 32.67±0.01 98.99±1.90 270 99.6 130 ± 0.29 6.9± 0.12 tds = total dissolved solid, e.c = electrical conductivity, figure 3. a) flow rates and b) porosity of ceramic filters: c60-25-15 sintered at 800, 850, 900 and 950°c. b) the micro-structure of ceramic filters in this section, the microstructures of c60-25-15 ceramic filters sintered in the range of 800 950°c with different performance were investigated. the porosity in microstructure is one of the physical properties of ceramic materials and one of the significant factors that affect the mechanical properties. the desired flow rate and microbial removal efficiency value can be achieved due to the defects such as porosity and crack occurred during production of ceramic materials and development of microstructure after firing. from the analysis, there were strong correlations between flow rate and sintering temperature of the clay filter. this might be due to the formation networked pores when the combustible materials burnout with the increasing in sintering temperature. images obtained by electron microscopy techniques, which now can be considered not only as research tools, but also as very valuable instruments for quality control of microstructures. as indicated on the sem images (figure 4a) the enyew amare & tegene desalegn ejssd, v 5 (2), 2018 8 © adama science & technology university https://ejssd.astu.edu.et average pore size increased with the increasing sintering temperature due to the overlapping of small pores large pores at higher sintering temperature were created. hence, the sem micrograph images of the mentioned composite ceramic filters confirmed as sintering temperature highly influence the performance of the filters. figure 4a. sem micrographs of the fractured surface of c60-25-15 sintered at 800, 850, 900 and 950°c. figure 4b. sem micrographs of the fractured surface of c60-25-15 sintered at 850°c. enyew amare & tegene desalegn ejssd, v 5 (2), 2018 9 © adama science & technology university https://ejssd.astu.edu.et c) ft-ir analysis ftir studies of the filters help in the identification of various forms of the minerals present in the sintered filter elements before and after usage. in the ir studies, the coupled vibrations are appreciable due to the availability of various groups. most of the bands such as 3696cm–1, 3622 cm–1, 3450 cm–1, 1033 cm–1, 917 cm–1, 795 cm–1, 692cm–1, 533cm–1, 466 cm–1 show the presence of kaolinite (franco, 2004). as indicated on figure 5a, the vibrations observed at ~ 917 cm–1 indicates the possibility of the presence of hematite (farmer, 1974). whereas 3622 cm–1,  1631 cm–1, 1033 cm–1 are also indicative of gypsum and  693 cm–1 shows the possibility of the presence of calcite (farmer, 1974). a strong band at 3696 cm–1, 3622 cm–1 and 3450 cm–1 indicate the possibility of the hydroxyl linkage. however, a broadband at 3450 cm–1 and a band at 1633 cm–1 in the spectra of clay ceramic filter suggests the possibility of water of hydration in the sample. ftir spectrum (figure 5a and b) revealed the difference between the functional groups between the filter elements before and after usage. ft-ir spectrum revealed that the hydroxyl groups on the adsorbent surface were involved in the sorption of ions. anion exchange and electrostatic interaction were suggested as the main mechanisms involved in the sorption of ions on the adsorbent. the changes of stretching frequency of treated filter material compared to untreated filter material confirm the chemical modification. 4000 3500 3000 2500 2000 1500 1000 500 0 10 20 30 40 50 2023 2933 1631 466 533 692 795 917 1033 3450 3622 3696 p e rc e n t t ra n s m it a n c e wave number (cm -1 ) figure 5a. untreated ft-ir spectrum of c900-60-25-15 enyew amare & tegene desalegn ejssd, v 5 (2), 2018 10 © adama science & technology university https://ejssd.astu.edu.et 4000 3500 3000 2500 2000 1500 1000 500 5 10 15 20 25 30 35 40 6922936 2352 1631 467 790 1050 3450 3623 p e rc e n t t ra n s m it a n c e wavenumber(cm -1 ) figure 5b. used ft-ir spectrum of c900-60-25-15 4. conclusion the quality of drinking water, especially in developing countries can be enormously improved by the use of the clay-sawdust composite filter. from the obtained results within the limit of this research, it can be concluded that the sintering temperature of the filter element influences the microstructure, porosity, flow rate and e. coli removal efficiency of the ceramic filters. acknowledgments the researchers would like to acknowledge adama science and technology university research affairs for the financial support and osho fluoride removal technology center for providing laboratory facilities. reference ajayi, b. a., lamidi y. d. 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(2017). clay ceramic filter for water treatment, materials science and applied chemistry, 34, 69–74. 12 1 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper medicinal plant syzygium guineense (willd.) dc leaf extract mediated green synthesis of ag nanoparticles: investigation of their antibacterial activity tegene desalegn1,, h c ananda murthy1,*, yeshaneh adimasu2 1department of applied chemistry, school of applied natural science, adama science and technology university, p o box 1888, adama, ethiopia 2department of applied biology, school of applied natural sciences, adama science and technology university, p o box: 1888, adama, ethiopia article info abstract article history: received 27 july 2020 received in revised form 29 september 2020 accepted 10 october 2020 the medicinal plant, syzygium guineense (willd.) dc mediated green silver nanoparticles (sygag nps) were successfully synthesized for the first time in ethiopia. the synergistic influence of biomolecules of the plant leaf extract such as alkaloids, phenolic compounds, tannins, saponins and glycosides with ag nps towards the antibacterial activity has been investigated. the synthesized nanoparticles were characterized by uv-vis, uv-drs, ft-ir, xrd, sem, edxa, tem, hrtem and saed techniques. the presence of absorbance maxima, λmax at 452 nm confirms the formation of syg-ag nps. the energy gap, eg of nps, was found to be 2.1 ev. ftir spectra confirmed the presence of biomolecules in the extract and nps. the presence of 4 sharp peaks in the xrd pattern of nps confirmed highly crystalline nature of nps. the purity of the nps was confirmed by sem-edax analysis. the average particle size of nps was found to be 27.62 nm. tem-hrtem-saed analysis resulted in d-spacing values of 0.2396 nm which corresponds to ag (111) lattice fringes of syg-ag nps. the d-spacing value of the derived diffraction planes from 4 major spots; d111ag = 0.2428 nm, d200ag = 0.2056 nm, d220ag = 0.1483 nm and d311ag = 0.1263 nm, are in agreement with the xrd data. the antibacterial test results showed synergistic effect against both gram positive bacteria, s. aureus (11±0.04mm), and gram negative bacteria e. coli (12±0.012 mm), p. aeruginosa (10±0.1 mm), and e. aerogenes (13±0.032 mm), respectively, proving potentiality of syg-ag nps as a remedy for infectious diseases caused by tested pathogens. keywords: medicinal plants green synthesis syzygium guineense (willd.) dc syg-ag nps antibacterial activity 1. introduction ethiopia is one of the six centers of biodiversity in the world with 6,500 species of higher plants where traditional medicine plays a significant role and vast majority of population lives in rural areas with little access to health services (gebrehiwet tesfahuneygn and gebremichael gebreegziabher, 2019). in recent years numerous ethiopian medicinal plants have been validated in a scientific empirical framework through  corresponding author, e-mail: tegened@yahoo.com and anandkps350@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.265 phytochemical analysis and subsequent bioassays (judžentienė, 2016). the medicinal plants species are used to treat many diseases in ethiopia (balcha abera, 2014). syzygium guineense (willd.) dc is a medium-sized or tall evergreen tree, 15 30 m high. its amharic name is ‘dokma’, whereas, in english it is called by several names such as water pear, water boom and water berry. the ripe fruits are edible by humans, birds, and some wild animals. http://www.ejssd.astu.edu/ mailto:tegened@yahoo.com https://doi.org/10.20372/ejssdastu:v8.i1.2021................ tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 2 in southern ethiopia s. guineense is a muchappreciated shade tree for both the homestead and the home garden. the research on the fabrication of plant mediated ag nps for biomedical, environmental and agricultural applications has been in the forefront for the last few years. the green ag nps have been used for photocatalytic, electrocatalytic, organic dye degradation, biomedical, pharmaceutical, cosmetic, energy and catalytic applications since many decades (ananda murthy and prakash, 2020). these ag nanostructures such as nanoparticles, nanocrystals, nanorods, nanotubes, nanosheets exhibit versatile properties and hence found to exhibit inhibitory activity against many microorganisms and bacterial strains (hemmati et al., 2020). a very few medicinal plants such as azadirachta indica (ahmed et al. 2016), dioscorea bulbifera (ghosh et al., 2015), barleria prionitis (sougata et al. 2016), caesalpinia bonducella (saranya sukumar and agneeswaran rudrasenan, 2020), hagenia abyssinica (murthy et al., 2020) have been applied to synthesize silver, gold, copper and their oxides in the recent past for multifunctional applications. but no significant work has been done especially with the application of biomolecules of medicinal plant extracts as reducing and capping agents for the synthesis of ag nps in ethiopia for biomedical, photocatalytic, electrochemical sensor and antibacterial applications. in this work, a simple and eco-friendly green synthesis of ag nanoparticles using medicinal plant syzygium guineense (syg) leaf extract at low temperature was proposed to investigate synergistic influence of phytochemicals and ag nps on bacterial strains. the synthesised syg-ag nps have been characterised by uv-vis, uv-drs, ft-ir, xrd, sem, edxa, tem, hrtem and saed techniques and investigated for their in vitro antibacterial activity. 2. materials and methods 2.1. materials and reagent all the chemicals, agno3, ethanol, dimethyl sulfoxide (dmso) used in the experiments were of analytical grade (purchased from merck chemical industrial company) and used without any further purification. 2.2. collection and authentication of plant materials syzygium guineense (willd.) dc plant leaves were collected from the arsi zone, ethiopia. the identification of the plant syzygium guineense (voucher code eb006) was performed at the national herbarium, department of biology, addis ababa university, addis ababa, ethiopia. 2.3. preparation of plant leaf extract the leaves of syzygium guineense were surface cleaned and washed repeatedly with tap water followed by distilled water to remove dust particles and then allowed to dry under shadow for 15 days to remove moisture contents from the leaves. this procedure has been adapted from the previously published work (murthy et al., 2020). the dried leaves were ground using grinding machine followed by packing in a brown bottle. the extraction was carried out by taking 20 g of powdered leaves of syzygium guineense in a 500 ml of conical flask containing 400 ml of deionized water. the flask was later covered with aluminum foil, to prevent the effect of light. after that the mixture was shaken using mechanical shaker for 90 min. and allowed to warm at 50°c for 1 hr. on magnetic stirrer, then it was allowed to cool down to room temperature overnight. the prepared solution was filtered through whatman no.1 filter paper to get clear solution. the filtrate was stored at 4°c for future experiments. 2.4. green synthesis of syg-ag nps a 0.2 m aqueous agno3 solution was prepared and stored in brown bottles. 100 ml of leaf extract was mixed with 400 ml of 0.2 m agno3 solution (1:4) slowly dropwise with constant stirring (kumar et al., 2019). the mixture has been incubated at room temperature for 24 hrs. the change in color from blue to light brownish visually indicates the formation of ag nps and then the solution was centrifuged for 15 min at 10000 rpm. the obtained syg-ag nps were washed thrice by deionized water and ethanol to remove any impurities. thereafter, the nps were allowed to dry and ground so as to be used for further analysis (murthy et al., 2018). 2.5. characterization techniques the uv-vis absorbance and reflectance spectra of the samples were recorded in the range of 200–800 nm using shimadzu’s uv-2600, uv-vis spectrophotometer. the ag nanoparticle solution was prepared by mixing the freshly prepared plant extract solution with ag solution tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 3 after appropriate dilution. fourier transform-infrared spectroscopy (ft-ir) spectrum (65 ft-ir perkinelmer) was recorded using kbr pellets in the range of 400–4000 cm−1. x-ray diffraction (xrd-shimadzu x-ray diffractometer (pxrd-7000) analytical technique was used to reveal the crystalline nature of g-cu nps. the scanning electron microscopy with energydispersive x-ray spectroscopy (sem-edx-evo 18 model with low vacuum facility and alto 1000 cryo attachment) and transmission electron microscope with high-resolution (jeol jem 2100 hrtem) were used for understanding morphological and structural features of syg-ag nps (kumar et al., 2020). gatan digital micrograph software was used to evaluate the d-spacing values of lattice fringes. particle size was computed by using imagej application. 2.6. method of antibacterial evaluation all the antibacterial tests were conducted at oromia public health research, capacity building & quality assurance laboratory, adama, ethiopia. the in-vitro antibacterial activity of syg-ag nps was evaluated using agar disc-diffusion method against selected one gram positive bacterial strain (staphylococcus aureus) and three gram negative pathogenic bacterial strains (escherichia coli, pseudomonas aeruginosa and enterobacter aerogenes). prior to antibacterial activity test, the bacterial strains were cultured in nutrient broth for 24 hrs to obtain logarithmic growth phase of the test bacteria. a standardized inoculum of the bacteria is swabbed onto the surface of mueller-hinton agar (mha) plate. the actively growing bacterial cultures of 1.3×108 cfu/ml concentration were inoculated/spread onto the mha plate (turbidity was adjusted with tsb to match 0.5 mcfarland standard). the nanoparticles extract was prepared with four different concentrations in dimethyl sulfoxide. four concentrations (6.25, 12.5, 25 and 50 µg/µl) of the synthesized nanoparticles were added to the respectively labeled wells. the antibiotic discs of 6 mm diameter were applied to agar surface using forceps with gentle pressure and then impregnated with the dissolved extract. chloramphenicol disc was used as a positive control while dmso was taken as negative control. the plates were incubated at 35 ±2°c in an ambient air incubator for 18-24 hrs. the antibacterial activity was evaluated in terms of zone of inhibition, measured to the nearest millimeters (mm) using a ruler and recorded. 3. results and discussions 3.1. synthesis of syg-ag nps the syg-ag nps were synthesized by using silver nitrate as a precursor and syzygium guineense (willd.) dc plant leaf extract as a reducing and capping agent. the presence of alkaloids, phenolic compounds, tannins, saponins, anthraquinone glycosides and cardiac glycosides was confirmed during the phytochemical screening of syzygium guineense leaf extract. the details of the phytochemicals present in the extract are as given in table 1. three stages of formation of nps includes: reduction of metal ions, formation of cluster and growth of nanoparticles. it is learnt that the tautomeric transformation of polyphenols from enol form to keto form would release reactive hydrogen atom that reduces silver ions to silver nanoparticles. in addition, the enzymes of leaf extract also assist silver ions to form an enzyme substrate complex resulting into formation of protein capped silver nps (roy et al., 2019). it is also understood that the phenolic compounds act as ligand and bind to metal ions and reduce them and cap them to form nanoparticles. these ligands also act as particle size controllers as reported by the earlier researcher (azarbani & shiravand, 2020). table 1: the details of phytoconstituents screening of syzygium guineense plant leaves extract. sl. no. phytoconstituents test / reagent result 1 alkaloids wagner’s reagent + 2 tannins koh + 3 flavonoids shinoda test 4 terpenoids salkowski test 5 anthraquinone glycosides borntrager's test + 6 cardiac glycosides keller-kiliani test + 7 saponins frothing test + 8 phenols fecl3 + ‘+’ indicates the presence and ‘-’ indicates the absence tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 4 primary components of syzygium guineense extract are alkaloids, phenolic compounds, tannins, saponins, anthraquinone glycosides and cardiac glycosides. the antioxidant properties of phenolic compounds are primarily due to their high inclination towards chelating the metals. phenolic compounds contain hydroxyl and carboxylic groups which have very high tendency to bind metal ions. metal ions in solution interact with phenolic compounds which help in the nucleation and formation of ag nps. 3.2. characterization of syg-ag nps the syg-ag nps were characterized using uv-vis, uv-drs, ft-ir, xrd, sem, edxa, tem, hrtem and saed techniques. 3.2.1. uv-vis spectral analysis the uv-vis absorbance spectrum recorded for instantaneously synthesized syg-ag nps exhibited λmax of 452 as shown in figure 1a, just after 10 min of mixing plant extract with copper nitrate solution in 1:4 ratios. this absorption band is basically due to surface plasmon resonance of syg-ag nps. the absorbance spectrum recorded after 30 min of forming nps, exhibited another identical absorbance band at λmax of 452 nm (figure 1b). the enhanced absorbance in the 2nd band, clearly confirm the increased concentration of nps. as the time proceeds on, the reduction of copper ions is followed by nucleation of small cluster of copper atoms to form nanoparticles in the presence of biomolecules of plant extract which are possibly believed to have acted as reducing agent and stabilizing agent. poly phenolic compounds usually help in the reduction of silver ions into silver atoms which form cluster and nanoparticles at the later stage. figure 1: (a) and (b) uv-vis absorbance spectrum of syg-ag nps at different time intervals (c) uv-vis diffused reflectance spectrum of syg-ag nps. (d) tauc plot of syg-ag nps showing eg value. tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 5 figure 2: the xrd pattern of syg-ag nps. a similar result was reported after the analysis of synthesized ag nps by using the lustrum lucidum leaf extract (huang et al., 2020) and persea americana seed extract (girón-vázquez et al., 2019). the surface plasmon absorbance presents a set of different λmax values for nps synthesised using different plant extracts which is possibly due to morphological features of the nps. similarly, the uv-vis diffused reflectance spectrum was recorded (figure 1c). the band gap energy of syg-ag nps was evaluated using tauc plot as shown in figure 1d by using the data obtained in reflectance spectra utilizing kubelka-munk function. the band gap energy, eg of syg-ag nps was found to be 2.1 ev. 3.2.2. xrd analysis the xrd diffraction pattern of syg-ag nps is presented in figure 2. the peaks at 2θ values = 38.14o, 44.72o, and 64.50o, and 77.42o corresponds to (111), (200), (220) and (311) lattice planes of face centred cubic structure of ag nps and the diffraction results were in good agreement with the data of icpd file no. 00-004-7383 (fm3m) (sadeghi & gholamhoseinpoor, 2015). 3.2.3. ft-ir spectral analysis the ftir spectra of syg plant extract and syg-ag nps is presented in figure 3. ftir spectra confirmed the presence of biomolecules in the extract and nps. the broad peaks appeared in the region between 3391 and 2926 cm-1 corresponds to –oh stretching vibration and sp 3 c-h stretching vibrations, respectively. the peak at 1623 cm-1 corresponds to c=o stretching of carbonyl groups. the sharp peak around 1450 cm−1 shows the presence of −coo group of carboxylic acid. it is also believed that the amine and carboxylate group present in the syg plant leaf extract responsible for the binding of proteins with the surface of ag and thereby leading to the stabilization of the biosynthesized nanoparticles. the peaks represented by 1350 cm-1 shows c-n stretching of amide. the medium peak at 1160 cm-1 corresponds to c-o stretching of phenolic compounds. the c-o-c stretching appears at 1038 cm-1. the bending vibrations of ag–o–h bonds resulted in a small peak at 800 cm−1 which can be attributed to the presence of the ag–o bond. the last peak at 665 cm-1 corresponds to bending modes of vibrations of c–h bond. the small shift in the ir bands indicates the possible reaction of silver ions and synthesis of nanoparticles in the extract. ftir analysis results confirmed the presence of various phytochemicals of syzygium guineense leaf extract such as alkaloids, phenolic compounds, tannins, saponins, anthraquinone glycosides and cardiac glycosides involved in the synthesis of syg-ag nps. figure 3: the ftir spectra of syg plant extract and syg-ag nps. 3.2.4. morphological and compositional analysis by sem-edax the morphological features of synthesized syg-ag nps as depicted by sem micrographs are shown in figure 4a and 4b. the sem images also depicted tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 6 varieties of nanosized particles with diversified size ranges as well as shapes. all the possible nearly spherical and diverse shapes such as hexagonal, cylindrical, triangular and prismatic shapes of ag nps with varying particle sizes were found in the micrographs. the average grain size of ag nps was found to be in the range between 10 and 40 nm (velgosova et al., 2019). the presence of less agglomerated ag nps possibly due to moderate surface area which yielded small sized particles. the ag nps were found to be as small as 10.1 nm in their dimension which clearly confirms the efficient role of biomolecules as stabilizing agents preventing the growth of clusters of silver atoms to bigger nps. the chemical composition of the nps was studied by edax analysis. figure 4c shows the edax spectrum obtained for the syg-ag nps. the peaks corresponding to elemental ag, c and cl were clearly identified and additional peak for au appeared due to the usage of standard during the analysis. it is also possibly believed that the presence of c is basically from the capped bioactive compounds. the reduction of silver ions to ag nps is facilitated by the biomolecules of plant extract containing surface hydroxyl groups. figure 4: (a) and (b) sem micrographs of vea-ag nps (c) edax spectrum of syg-ag nps. tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 7 3.2.5. tem, hrtem and saed analysis in order to explore deep insights into the morphological and structural features of the syg-ag nps, tem, hrtem and saed technical micrographs and patterns were utilized. the hrtem images of assynthesized syg-ag nps (figure 5) shows that the synthesized nps are nearly spherical but exhibited varieties of shapes. figure 5: the tem micrographs showing syg-ag nps with a) cylindrical, b) prismatic c) hexagonal, and d) triangular shapes with nearly spherical shapes. the smaller nps as small as 10.1 nm confirm the efficient role of bioactive components of syzygium guineense plant extract as capping and stabilizing agents. otherwise nps would have been agglomerated to yield larger nps in an elongated form. in addition, the variation in size of syg-ag nps is probably due to the presence of polyphenolic compounds which have strong attractive forces and holds the particles together. the tem micrographs which exhibited very finely grained syg-ag nps with cylindrical, prismatic, hexagonal, triangular shapes as well as nearly spherical shapes are presented in figure 5a to 5d. the nearly spherical particles with varying sizes from 10.1 nm to 54.7 nm with an average particle size of 27.62 nm as determined by image j application are as shown in figure 6a and 6b. figure 6: tem images of as-synthesized syg-ag nps at (a) lower magnification (100 nm) and (b) higher magnification (50 nm) (c) saed pattern with 1 to 6 spots and (d) hrtem image showing lattice fringes of syg-ag nps with d-spacing of 0.2396 nm. the saed pattern of syg-ag nps (figure 6c) contained six spots each corresponding to specific crystal planes. the most prominent 4 spots were represented in colored concentric circles which represents (111), (200), (220) and (311) planes. the dspacing of 0.2396 nm for ag (111) plane is as shown in figure 6d. hrtem morphology of syg-ag nps with magnified lattice fringes, ifft patterns and profile of ifft with d-spacing value for ag (111) plane (figure 6d) are presented in figure 7a, 7b, 7c and 7d respectively. the image analysis to arrive at d-spacing value has been carried out by using gatan digital micrograph software application which resulted in dhkl value of 0.2396 nm a set of crystal planes at the surface of ag nps. the d-spacing values for the most prominent four spots depicted in the saed pattern of syg-ag nps (figure 6c) are presented in table 2. each spot on the saed pattern corresponds to specific set of lattice planes. the xrd pattern of nps presented earlier in figure 3, revealed 4 major peaks corresponding to (111), (200), (220) and (311) planes of fcc structure of pure ag (icpd file no. 00-004-7383 (fm3m)). the d-spacing tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 8 table 2: the d-spacing values for syg-ag nps from saed pattern. spot no. dspacing (nm) rec. pos. (1/nm) degrees to spot 1 degrees to xaxis amplitude 1 0.2428 4.145 0.00 80.37 2839.10 2 0.2126 4.678 2.04 78.33 4168.58 3 0.2056 4.895 52.10 28.27 4484.95 4 0.1483 6.756 6.11 74.26 1295.65 5 0.1263 7.954 5.87 86.24 5564.48 6 0.09527 10.40 19.92 60.45 4062.21 values of the derived diffraction planes corresponding to spots 1, 3, 4 and 5; d111ag = 0.2428 nm, d200ag = 0.2056 nm, d220ag = 0.1483 nm and d311ag = 0.1263 nm, are in agreement with the standard d-spacing values of ag (icpd file no. 00-004-7383 (fm3m)) structure. figure 7: hrtem morphology of syg-ag nps (a) magnified lattice fringes (b) ifft patterns (c) profile of ifft with d-spacing distance. 3.3. antibacterial activity the syg-cu/cu2o/cuo nps exhibited broad range of antibacterial activities against all tested pathogens; s. aureus, e. coli, p. aeruginosa, and e. aerogenes. the present work evaluated synergistic influence of biomolecules with nps against 4 pathogens. the zone of inhibitions for chloramphenicol, dmso and nps with four concentrations (6.25, 12.5, 25 and 50 µg/µl). pure ag nps were proved to exhibit excellent antibacterial activity. accordingly, syg-ag nps were found to show better antibacterial activity against gram positive bacteria than gram negative bacteria which is believed to be due to the structural differences in the cell walls of bacteria (abebe et al., 2020). syg-ag nps were found to show better antibacterial activity against gram negative bacteria than gram positive bacteria which is believed to be due to the structural differences in the cell walls of bacteria. the antibacterial activity of nps can be partially attributed to the presence of bioactive compounds on the surface of nps as capping and stabilizing agents. in this regard, the activity was pronounceable against s. aureus. the highest zone of inhibition (mm) recorded with 50 µg/µl of syg-ag nps against e. aerogenes bacteria was 13±0.032 mm and the lowest zone of inhibition (mm) recorded against p. aeruginosa bacteria was 10±0.1 mm (table 3). the wide zone of inhibitions of syg-ag nps against pathogens confirm their great potentiality as a remedy for infectious diseases caused by the tested bacterial pathogens. additionally, the standard disc chloramphenicol showed comparable zone of inhibition with the syg-ag nps, which is small and it can be attributed to development of resistance by bacteria against chloramphenicol. the zone of inhibition values for syg-ag nps was found to be moderately lower for s. aureus, e. coli and e. aerogenes except p. aeruginosa when compared with that of positive control chloramphenicol. it is mainly due to the differences in the chemical structure of the bacterial cell walls and as a consequence different types of interactions occur between differently sized nps and bacterial strains. the interaction between ag nps and microorganisms starts with adhesion of ag nps to the microbial cell wall and membrane, which is based on electrostatic attraction between the negatively charged microbial cell membrane and positively or less negatively charged ag nps. zeta potential is another physico-chemical property influence antimicrobial activity since the interaction between nps tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 9 table 3: the variation of zone of inhibitions for different bacteria by syg-ag nps. concentration of nps (µg/µl) bacterial strains and zone of inhibition in mm s. aureus atcc25923 e. coli atcc25992 p. aeruginosa atcc27853 e. aerogenes atcc13048 50 11±0.04 12±0.012 10±0.1 13±0.032 25 11±0.005 10±0.06 8±0.05 10±0.103 12.5 6±0.008 8±0.017 6±0.057 8±0.007 6.25 6±0.11 6±0.002 6±0.043 6±0.041 chloramphenicol 24±0.14 20±0.015 6±0.001 30±0.016 dmso 6±0.006 6±0.02 6±0.003 6±0.01 table 4: comparative data of antibacterial activities of ag nps synthesised by using various plant extracts. sl. no. plant extract zone of inhibition (mm) tested pathogens reference 1 bergenia cili(phull et al., 2016) ata 8.5 s. aureus (phull et al. 2016) 2 balloon flower plants 12 e. coli (anbu et al., 2019) 3 aloe fleurentiniorum 12, 14.5 e. coli, s. aureus (salmen & alharbi, 2020) 4 chenopodium murale 12.7 s. aureus (abdel-aziz et al., 2014) 5 syzygium guineense 11, 12, 10, 13 s. aureus, e. coli, p. aeruginosa, e. aerogenes. present work 6 ocimum sanctum (tulsi) 14 e.coli (jain & mehata, 2017) 7 citrus paradisi (grapefruit red) 22 e.coli (ayinde et al., 2018) 8 coffea arabica 23, 21 e. coli, s. aureus (dhand et al., 2016) 9 banana peel extract 17, 20, 16, 12 e. coli, p. aurognosa, s. aureus, b. subtilis. (ibrahim, 2015) 10 allium cepa 24, 23, 25 e. coli, s. aureus, b. subtilis. (gomaa, 2017) 11 rosmarinus officinali 17.2, 18.8, 31.2, 16.2 e. coli, p. aurognosa, s. aureus, b. subtilis. (khafri, 2015) 12. cassia roxburghii leaf 33 e. coli (moteriya et al., 2017) and the cell membrane is based on electrostatic adhesion which is different for different bacterial strains. furthermore, ag nps could interact with protein parts of the outer membrane of bacterial strain, constitute complexes with oxygen, phosphorous, nitrogen or sulphur atom containing electron donors, and cause irreversibly changes in the cell wall structure. the moderate zone of inhibitions exhibited by the sygag nps is possibly because of the application of very small amounts of nps compared to the amount of nps utilized by various researchers. many mechanisms of antibacterial activity have been reported by the past researchers, accordingly, the action of syg-ag nps on the bacteria is yet to be explored fully. it is assumed that the syg-ag nps get adsorbed on to the cell wall of bacteria and interacts with the electronegative elements within the cell membrane. these results in failed metabolism and thereby leading to interference and disruption of transcription in bacteria and hence causes antibacterial activity by sygag nps. it is also believed that the synergistic effect of syg-ag nps with bioactive compounds of extract would have played significance influence to inhibit the activity of pathogenic bacteria. the antibacterial results obtained using syg-ag nps were found to be better when compared with an earlier tegene desalegn et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 10 work reported by many researchers (table 4). the highest zone of inhibition (mm) recorded with syg-ag nps against e. aerogenes bacteria was 13±0.032 mm which is higher than the zone of inhibition exhibited by ag nps synthesized by various plant extracts as mentioned in table 4. the last few plant extracts were proved to exhibit a higher zone of inhibition which can be attributed to the presence of different type of phytoconstituents. another possible mechanism of the inhibitory phenomenon was that the cell walls of gram-positive bacteria bound larger quantities of metal (ag) than gram-negative bacteria. most studies have shown that gram-negative bacterial growth is more affected by ag nps than gram-positive bacteria which can be attributed to thin cell walls that are easily penetrated, while grampositive bacteria have thicker cell wall (anbu et al., 2019). it is possibly understood that the helical structure of dna molecules would have disrupted by the action of syg-ag nps. in addition, electrochemical potential across the cell membrane decreases up on interaction with the released ag metal ion by syg-ag nps affecting integrity of the membrane. 4. conclusion the application of medicinal plant, syzygium guineense leaf extract towards the green synthesis of silver (syg-ag) nanostructures was successful. the uv-vis spectra, xrd pattern and ftir spectra confirmed the formation of crystalline syg-ag nps in the presence of biomolecules such as ployphenolics, tannins, glycosides and proteins of the plant extract. sem and tem micrographs of syg-ag nps revealed cylindrical, prismatic, hexagonal, triangular and spherical morphologies. hrtem-saed analysis confirmed the presence of crystalline ag by the observation of ag (111), (200), (220) and (311) lattice fringes in syg-ag nps with the calculated d-spacing values matching exactly with the standard value for ag. the syg-ag nps are identified as effective antibacterial agents against multiple microbes of various strains. the synergistic influence of bioactive compounds, syg-ag nps and antibiotic ampicillin proved to be highly effective against pathogens, gram-positive and gramnegative bacterial strains s. aureus, e. coli, p. aeruginosa, and e. aerogenes. it is expected that this accomplished work will initiate research towards the green synthesis of fabricated metallic nanoparticles for prospective biomedical applications. acknowledgments this work has been funded by the project (ansd/04/0453/11-2018) approved by the research and technology transfer office, sanctioned by adama science and technology university, ethiopia. the authors gratefully acknowledge adama science and technology university for the financial support and laboratory facility to conduct this research work. reference abdel-aziz, m. s., shaheen, m. s., el-nekeety, a. a., & abdel-wahhab, m. a. 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(2019). influence of different plants extracts on silver nanoparticles green synthesis. archives of metallurgy and materials, 64(2): 665–670. https://doi.org/10.24425/amm.2019.127596. 67 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 engineering and chemical characterisation of natural bitumen resources from nigeria ademila o.* and ojo f. g. department of earth sciences, adekunle ajasin university, akungba-akoko, nigeria, *corresponding author, e-mail: omowumi.ademila@aaua.edu.ng abstract engineering and chemical properties of bitumen in agbabu were evaluated for their suitability in road pavement construction. raw samples of natural bitumen were collected in agbagbu, mile 2 and mulekangbo, ondo state, nigeria. the engineering properties analysis involves bitumen penetration, flash and fire points, water content, loss on heating and specific gravity. chemical evaluation includes analysis of heavy metals by the use of atomic absorption spectroscopy (aas) and analysis of poly aromatic hydrocarbons (pahs) using gas chromatography/mass spectrometer (gcms). agbabu and mulekangbo bitumen samples fall within 200/300 penetration grade, classified as temperature susceptible bitumen, while samples of mile 2 fall within 100/150 penetration grade, classified as conventional paving bitumen. thus, agbabu and mulekangbo bitumen can be used in temperate regions of the world, while mile 2 bitumen can best be applied in tropics, after upgrading by modifiers. the results of aas indicate a high concentration of iron in the samples in the decreasing order of fe<zn<cu<mn<pb<ni. for agbabu bitumen sample, the concentration indicates fe (509 mg/kg), zn (16 mg/kg), cu (14 mg/kg), pb (1 mg/kg), ni, cd and mn are negligible, mile 2 bitumen sample indicates fe (8605 mg/kg), zn (36 mg/kg), cu (35 mg/kg) mn (27 mg/kg), ni and cd are negligible; for mulekangbo bitumen sample: fe (8905 mg/kg), zn (48 mg/kg), cu (39 mg/kg), mn (37 mg/kg), pb (7 mg/kg), mn (37 mg/kg), ni (1 mg/kg) and cd is negligible. metals like pb, ni, cd, even though present in small concentration can cause environmental hazard. gcms analysis revealed high percentage of pahs such as chrysene, pyrene, fluorene, phenanthrene and anthracene in mulekangbo bitumen sample, while agbabu and mile 2 bitumen samples indicate low percentage of target pahs. pahs present in bitumen sample of mulekangbo can be carcinogenic and mutagenic, thus, exposure to these compounds can pose health/environmental risks. this study recommends clean technology during refining process to remove hazardous pahs from the bitumen to prevent human and environmental health challenges during utilization. keywords: natural bitumen, engineering properties, heavy metals, pahs, pavement construction 1. introduction bitumen is a mixture of organic liquids that are highly viscous, black, sticky, composed primarily of highly condensed polycyclic aromatic hydrocarbons and metals such as nickel, iron and vanadium. in other words, bitumens contain a complex mixture of aliphatic compounds, cyclic alkanes, aromatic hydrocarbons, pahs and mailto:omowumi.ademila@aaua.edu.ng ademila o. & ojo f.g. ejssd, v 5 (2), 2018 68 © adama science & technology university https://ejssd.astu.edu.et heterocyclic compounds containing nitrogen, oxygen and sulfur atoms, and metals (e.g. iron, nickel, and vanadium). elemental analyses indicate that most bitumens contain primarily hydrocarbons, i.e. carbon, 79–88%; hydrogen, 7–13%; sulphur, traces to 8%; oxygen, 2–8%; nitrogen, 3%; and the metals vanadium and nickel in parts per million (speight, 2000). the exact chemical composition of bitumen varies depending on the chemical complexity of the original crude petroleum and the manufacturing processes. consequently, no two bitumen products are chemically identical, and chemical analysis cannot be used to define the exact chemical structure or chemical composition of bitumens. it is soluble in carbon disulphide, chloroform, ether and acetone, partially soluble in aromatic organic solvents, and insoluble in water at 20°c (ipcs, 2004). the compositional value of its constituents influences the industrial applications of bitumen. the principal refinery process used for the manufacture of bitumen is a two-step distillation: atmospheric distillation followed by vacuum distillation. the distillation is designed to remove polycyclic aromatic hydrocarbons (pahs) from bitumen. this results in very low concentrations of pah in the final product bitumen. this is sometimes followed by air rectification (mild oxidation) and/or oxidation (severe oxidation) depending on the required final product properties (eurobitume and asphalt institute, 2015). bitumen originates with chemical and physical attributes as immature oil which has undergone little secondary migration. the greatest amount of natural bitumen results from the bacterial degradation under aerobic conditions of originally light crude oils at depths of about 1,524 m or less and temperature below 80°c. the biodegradation involves loss of most of the molecular weight volatile paraffins and naphthenes, resulting in a crude oil that is very dense, highly viscous, black or dark brown and asphaltic (meyer et al., 2007). bitumen either in natural form or obtained from petroleum consists of four fractions namely: saturates, aromatics, resins and asphaltenes. pahs often play a key role in the hazard evaluations of materials with respect to their impact on health and the environment. recently, pahs have played an important role in the outcome of the cancer hazard assessment of occupational exposure to bitumen and its emissions. crude oils contain low parts of pah/pac and as such low (ppm) levels may be present in bitumen. the pahs are mainly released during the burning of petroleum and its derivatives (usepa, 2007). hydrocarbon having benzene properties are called aromatic, and in the presence of two or more fused benzene rings, they become known as pahs. according to lopes (2008), the acute symptoms in pavers involve: eye irritation, nose and throat irritation, headache, dryness and skin irritation. hein et al. (2013) estimated that global bitumen and heavy oil resources are around 5.6 trillion barrels, with most of these located in the western hemisphere. the high viscosity of ademila o. & ojo f.g. ejssd, v 5 (2), 2018 69 © adama science & technology university https://ejssd.astu.edu.et bitumen prevents it from flowing to a wellbore under in-situ reservoir conditions. natural bitumens are naturally occurring deposits of asphaltlike material, these deposits have physical properties that are similar to those of petroleum derived asphalt, but the composition is different. they exist in two main forms; either as pare bitumen accumulated down-deep below the earth surface or outcrops as oil impregnated sand, which is generally known as tar sand or oil sand. in nigeria, natural bitumen has been found in ondo, ogun, lagos, edo and enugu states with a combined proven reserve of about 14.86 billion barrels with a quality estimated to be second largest in the world but yet to be explored for economic purposes. the major applications of bitumen are in paving for roads and airfields, hydraulic uses (such as dams, water reservoirs and sea-defence works), roofing, flooring and protection of metals against corrosion. more than 80% of bitumens are used in many different forms of road construction and maintenance. it is also the basic feedstock for petroleum production from tar sands. the extracts from bitumen are very rich in aromatics, which makes it a suitable feedstock for petrochemical industries (lurgi, 1987). the chemical composition of bitumen is a great determinant of its grade or quality. bitumen derived from different sources, or produced with different manufacturing processes and/or crudes can have wide variations in chemical compositions and other physicochemical properties with different levels of service benefits. any bitumen whose chemical composition and other physicochemical properties deviates significantly from compositions of bitumen of standard grades or known acceptable qualities can be unreliable in service for most engineering applications or cause unpredictable problems in its service usage (unep and ilo, 2004). this investigation of the engineering material is conducted due to the large reserves of natural bitumen resources and potentials for sustained production in large quantity in nigeria, high demand for better strength of road elements, lesser road maintenance, increase in traffic, poor construction materials and continuous road failure caused by rutting, cracking and moisture damage. thus, this study is necessitated to provide basic information of the quality and performance grade of the bitumen for the implementation of good resistance roads of high performance traffic loading, high bearing capacity and to ensure the health and safety of workers during the execution process of highway works. 2. description of the study area bitumen samples were collected from four different locations, agbabu, mile 2 (samples a and b) and mulekangbo sites, where bitumen outcrops occur in odigbo and okitipupa local government areas of ondo state, called bitumen belt of southwestern nigeria. it lies between latitudes 6° 31’ n and 6° 38’ n and longitudes 4° 46’ e and 4° 52’ e (figure 1). the location falls within the eastern dahomey basin and runs through edo, ademila o. & ojo f.g. ejssd, v 5 (2), 2018 70 © adama science & technology university https://ejssd.astu.edu.et ondo and ogun states (adegoke et al., 1980). it is an area of lowlands with few ridges about the lowlands, the hills are very high which are characteristic of the tropical rainforest of southwestern nigeria. the temperature is relatively high during the dry season with the temperature reaching about 30°c. the area is well drained by ne-sw trending rivers like oluwa, ufara, omilala, opeki, shasha, oba and ogun. the rivers dominate the drainage system of the study area and it’s mainly dendritic. some of the sample locations can be assessed by roads and footpaths while, other locations can only be assessed by footpaths. 3. geology of the study area geologically, the main bitumen belt in nigeria occurs on the eastern margin of a costal sedimentary basin known as the benin basin. the eastern ward limit of the benin basin is marked by the okitipupa high while, the basin extends westwards into togo and the volta delta (ghana). the crystalline basement rocks form the foundation of the whole area (fmsmd, 2006). the study area falls within the sedimentary terrain in the dahomey basin of southwestern, nigeria. the sedimentary terrain of agbabu falls within the eastern portion of the dahomey basin. the geologic sequence is composed of the nkporo shale, upper coal measures, imo shale group, coastal plain sands (benin formation) and quaternary coastal alluviumin (figure 2). the nkporo shale is made up of shale, sandy clay and lenses of sand. the imo shale group is composed off shale while the coastal plain sands has alternations of clay/sandy clay and clayey sand/sand. the quaternary coastal alluvium is composed of an alternating sequence of sand and silt/clay (jones & hockey, 1964). the aquifer units are sand, sandstones, clayey sand and dissolved/ fractured limestone which are unconfined and confined in nature. the study areas belong to the afowo formation of the cretaceous abeokuta group, uncomfortably overlying the basement. the afowo formation is composed of coarse to medium grained sandstone with variable but thick interbedded shale, siltstone and claystone. the sandy facies are tar bearing while the shale are organic rich. the dahomey basin is an atlantic margin basin containing mesozoiccenozoic sedimentary succession reaching a thickness of over 3000 m. it extends from southeastern ghana to the western flank of the niger delta. its stratigraphy is classified into abeokuta group, imo group, oshosun formation, ilaro formation and coastal plain sands and alluvium (jones & hockey, 1964). omatsola & adegoke (1981) recognized three formations belonging to the abeokuta group. these are: ise formation (neocomian-albian) consisting essentially of continental sands, grits and siltstones, overlying the basement complex. overlying the ise formation is the afowo formation (turonianmaastrichtian) consisting of coarse to ademila o. & ojo f.g. ejssd, v 5 (2), 2018 71 © adama science & technology university https://ejssd.astu.edu.et medium grained sandstones with interbeds of shale, siltstones and clay. the araromi formation (maastrichtianpaleocene) conformably overlies the afowo formation and consists of sands, overlain by dark-grey shales with interbeds of limestones and marl. figure 1. location map of the study area showing the sample locations 4. material and method 4.1. sample collection four natural bitumen samples were collected at four different locations within the richest bitumen spots at agbabu, mile 2 (samples a and b) and mulekangbo. one sample was collected from a standard extraction hole drilled with metal casing by early explorers of bitumen in agbabu. two bitumen samples were collected from the deposits within a water logged area, some kilometers away from agbabu community and the last bitumen sample was collected at the well drilled by the early explorers of mulekangbo community in a cocoa plantation site. the sample collection involved the use of dip stick, hand trowel, sterilized plastic containers, marker, gps (each sample location was plotted using a global positioning system) and paper tape. the samples were collected and properly kept in a well labeled plastic containers and were later taken to the laboratory for the required analysis. ademila o. & ojo f.g. ejssd, v 5 (2), 2018 72 © adama science & technology university https://ejssd.astu.edu.et figure 2. geological map of the study area 4.2. determination of flash and fire points the flash point tells the critical temperature above which suitable precautions are required to be taken to eliminate the danger of fire during heating. the flash-point is the temperature at which bitumen fume may flash, or spark. this temperature is usually 230°c or higher for common paving bitumen. the flash-point provides an indication of fire hazard and the test is frequently used to indicate whether a given product has been contaminated with materials of lower flash-point (astm d92-01 (2001)). test cup, a thermometer and a bunsen burner were used for the fire point experiment. the test cup used was filled with the bitumen sample to the standard level; thermometer was inserted into the cup and heated at the rate of 5°c/min. the test flame was lighted and adjusted to a diameter of 3.8 to 5.4 mm. the test flame was applied when the temperature read on the thermometer has reached each successive 2°c mark. a lighted flame was passed across the sample at interval of 15 seconds. the flash point was considered as the lowest liquid temperature at which application of the test flame caused the vapors of the sample to flash, while the fire point was considered as the temperature at which the test flame causes the sample to ignite and remain burning for at least 5 seconds. ademila o. & ojo f.g. ejssd, v 5 (2), 2018 73 © adama science & technology university https://ejssd.astu.edu.et 4.3. determination of loss on heating bitumen sample was scooped into the test cup and weighed to an accuracy of 0.01 gm at room temperature. then it was place in an oven and was heated for five hours at 163°c. after that, the sample from the oven was brought out and cooled to room temperature and the weight was taken at an accuracy of 0.01 gm, with the value noted and recorded. calculation i) loss on heating = weight of bitumen before heating – weight of bitumen after heating. ii) percentage of loss on heating = loss on heating / weight of bitumen before heating * 100. 4.4. determination of water content (water-in-bitumen) 100 g of bitumen sample was measured and transferred to a cylindrical container. sufficient trichloroethylene free from water was added to permit refluxing to take place and then bolt on the cover with a dry gasket in position and fixed the receiver and condenser in place. adequate flow of water through the condenser and heat to give a steady reflux action was ensured. continuous heating was ensured until the volume of water in the receiver remained constant. then the volume of water was then measured and its mass was recorded. then, the water content was calculated as a percentage by mass of original sample to the nearest 0.1%. 4.5. determination of specific gravity bitumen sample was heated in oven to melt. 100 g of the heated sample was weighed into a gravity bottle of a known weight and volume. the weights of the bottle plus the sample was taken and recorded. the sample was allowed to cool for about 30 minutes and the solvent (trichloroethylene) was added to the sample in the bottle to the standard mark. it was ensured that the bottle was shaken while adding the solvent to allow for outright dissolution of the sample. the bottle was then put in the water bath at 25°c for about one hour and refilled to the mark due to a little decrease in the level of the solvent in the bottle and weighed. the specific gravity of the bitumen sample was calculated as: specific gravity = density of natural bitumen/density of water at 4°c following standard procedure. 4.6. determination of penetration the penetrometer used for the conduction of this test was made up of a needle assembly with a total weight of 100 g and a device for releasing and locking in any position. the bitumen samples from each location was scooped in a test cup and heated until pouring temperature, and then cooled to room temperature. the sample container was then placed in the transfer dish with water at the required temperature of 25°c, from the constant temperature bath, the sample being completely covered with water at all times. the needle was then released ademila o. & ojo f.g. ejssd, v 5 (2), 2018 74 © adama science & technology university https://ejssd.astu.edu.et for 5 secs and relocked immediately at the end of the period and the penetration value was obtained from its digital indicator. care was taken not to disturb or jolt the apparatus when releasing the needle. this was repeated for all the samples. 4.7. determination of chemical composition the chemical composition includes the heavy metals and pahs analysis. the heavy metal is determined majorly by the use of atomic absorption spectrophotometer. the polycyclic aromatic hydrocarbons were determined by the use of the gcms. the materials used for this analysis include; measuring cylinder, beaker, conical flask, funnel, filter paper, hot plate, fume cupboard, aas, and the reagent used are: aqua regia (hcl + hno3) and perchloric acid. procedure: 0.5 gm of samples was weighed into a digesting flask and digestion was carried out with 10ml of mixture of conc. hno3 and hcl (aqua regia) with few drops of perchloric acid added. the mixture were heated on digesting block until the fume of the acid ceased and made up with distilled water into a 500 ml standard flask. analysis was carried out with aas vgp 210 following the standard procedure as described by the operation manual of the equipment. 4.8. pah analysis the bitumen sample was extracted using methanol and the extracts was transferred to 100 ml pear-shaped flasks and evaporated to nearly dryness under reduced pressure of 150 mbar at 35°c using a rotary evaporator fitted with thermostated heating bath). an additional 10 ml n-hexane was added to the concentrated extracts and evaporated to a small volume (about 1 ml). then the sample was transferred to 1.5 ml chromatographic vial for gas chromatography analysis. the pahs were quantified by internal calibration performed with a gcms (agilent gc6890/5973msd). for pahs analysis, a hp-5 ms column (aglient, length 30 m, i.e. 0.25 mm, film thickness of 0.25 mm) was employed with the following temperature program: 60–280°c at 6°c min−1, isothermal holding at 280°c for 20 min using helium as the carrier gas. the instrument was operated with an initial flow of 1.2 ml min−1, head pressure 0.03 mpa, and injection mode as follows: splitless (1 ml), temperature of injector: 280°c. the mass spectrometer (ms) was operated using the electron impact (ei) ionization mode at 70 ev (electron volt), scanning from 50 to 550 mass units at 0.82 s scan-1. all pahs were determined by selective ion monitoring. 5. result and discussion 5.1. engineering properties of bitumen samples the values obtained for flash and fire points of the natural bitumen samples of the study area are as shown in table 1. the values ranged from180°c 241°c and 220°c 288°c for flash and fire points respectively. mulekangbo ademila o. & ojo f.g. ejssd, v 5 (2), 2018 75 © adama science & technology university https://ejssd.astu.edu.et bitumen sample has the lowest flash and fire point values, while mile 2 (sample b) bitumen has the highest values. this result is similar with that of previous study by guma et al (2012) for two tested natural bitumen samples. the values of loss on heating ranged from 1.15% 2.52%. the result indicates that mile 2 (sample a) bitumen has the lowest value of percentage loss of water during heating, while agbabu bitumen sample has the highest value of percentage loss of water on heating. based on this result, only mile 2 (sample a) bitumen of all tested bitumen samples meets the requirement of 1% loss on heating (astm 1998) bitumen grading. the percentage of water present in the bitumen samples of mulekangbo and mile 2 (sample a) is 3.9% (table 1). agbabu bitumen sample has the lowest percentage of water of 1.9%. the high value obtained for mulekangbo and mile 2a samples may be due to their presence in waterlogged area. this high value in moisture in bitumen requires modification/upgrading of the bitumen in the study area to prevent reduction in adhesiveness of bitumen to aggregate during compaction in pavement construction. the specific gravity (gs) of the bitumen samples ranged from 0.68 – 0.84. the specific gravity of each sample compares favourably with that for asphalt standard of 1 maximum as given by astm d5-97 (1998). the penetration of bituminous material is a measure of the consistency of bitumen at a given temperature. this property in-turn indicates the quality and grade of bitumen. as can be observed from table 1, the values of penetration of bitumen fall in the range of 100 – 300 dmm. the penetration value of mile 2 (samples a and b) bitumen fall in the range of 100/150 for bitumen of acceptable grades commonly used to manufacture asphalt mixes, cut-back bitumen, bitumen emulsions and modified bitumen. an increase in penetration value of bitumen implies hardening of the material. this hardening of bitumen has a negative effect on the quality of bitumen. hardening of bitumen has been emphasized to be responsible for distresses such as breakdown and rupture in the pavement which led to premature failure of road (nassar et al, 2012). based on the bitumen grade summarized in table 2, two of the four bitumen samples collected (mile 2 bitumen (samples a and b)) fall within the grade 100/120 and 120/150 respectively, classified as conventional paving bitumen can be applied on road construction in the tropic regions like nigeria, when appropriately upgraded or modified in order to provide a variety of properties such as good resistance to aging, durability, high performance traffic loading and high bearing capacity. abgabu (sample c) and mulekangbo (sample d) bitumen flow at room temperature classified as temperature susceptible bitumen and can be best applied for road pavement in temperate regions of the world. ademila o. & ojo f.g. ejssd, v 5 (2), 2018 76 © adama science & technology university https://ejssd.astu.edu.et table 1. summary of the engineering properties of bitumen samples sample location water-inbitumen (%) penetratio n at 25 °c (dmm) gs loss on heating (%) flash point (°c) fire point (°c) sample a (mile 2a) 3.9 110 0.84 1.15 196 240 sample b (mile 2b) 2.2 150 0.68 2.35 241 288 sample c (agbabu) 1.9 206 0.68 2.52 238 277 sample d (mulekangbo) 3.9 226 0.82 2.25 180 220 table 2. the grade of bitumen bitumen location grade best possible use mile 2a (sample a) 100/120 conventional paving bitumen mile 2b (sample b) 120/150 conventional paving bitumen agbabu (sample c) 200/300 temperature susceptible bitumen mulekangbo (sample d) 200/300 temperature susceptible bitumen 5.2. trace metals in bitumen samples the concentration of trace metals in bitumen samples are shown in table 3. trace metals have been employed in the natural bitumen characterization. iron (fe) concentrations range from 509 to 8905 mg/kg. high level of iron (fe) in sample collected from mile 2 (8905 mg/kg) and mulekangbo (8605 mg/kg), in contrast to the sample collected from agbabu (509 mg/kg). the concentration of the elements for all the samples in decreasing order is as follow: fe > zn > cu >mn>pb. the concentration of iron is the highest (8905 mg/kg) while pb is the lowest (1.00 mg/kg). the concentration of heavy metals in the samples shows slight similarities with the work obtained by bakare et al. (2015). the exceptional high concentration of iron for sample collected from mile 2 (sample a) may be as a result of the presence of the sample in waterlogged area. the regular occurrences of the high rainfall and flooding have contributed to the leaching of most trace elements and this has contributed to the increased level of these metals. the relatively high levels of fe, pb and ni observed in the result of some of the samples may be associated with the bitumen sample obtained from the marine environment. the presence of manganese (mn) and lead (pb) in sample from mile 2 and mulekangbo, may pose environmental hazard and catalytic poisons during the refining of the bitumen. the differences that occur with other studies may be due to the fact that previous studies of ipinmoroti and aiyesanmi (2001) and adebiyi and omole (2007) were conducted on bituminous sand while the present study used flow bitumen obtained from ademila o. & ojo f.g. ejssd, v 5 (2), 2018 77 © adama science & technology university https://ejssd.astu.edu.et observatory wells. during the process of extraction of bitumen from bituminous sand, some of the metal contents might have been leached out from the sample, hence, the relatively lower concentrations of some metals reported. it is observed that work has not been carried on mulekangbo observatory well. the result of mulekangbo bitumen sample indicates high concentration of fe, mn, pb, and zn. these heavy metals when present in high quantity cause environmental hazards. the exceptionally high concentration of heavy metals may be due to contaminations during collection of the sample, because the sample was found in contact with biogenic materials and with water emanated from the well beneath. table 3: concentrations of trace metals (ppm) in bitumen samples sample locations heavy metals (mg/kg) agbabu mile 2 mulekangbo zn 16.00 48.00 36.00 cu 14.00 39.00 35.00 pb 1.00 7.00 5.00 ni nd 1.01 nd cd nd nd nd mn nd 37.00 27.00 fe 509.00 8905.00 8605.00 nd: not detected 5.3. polycyclic aromatic hydrocarbons the asphalt binders (or bitumen) release fumes which have pahs. the pahs belong to a class of complex chemical compound whose structure is in the form of linked benzene rings, and is widely distributed in the atmosphere. however, some pahs are considered to have carcinogenic and/or mutagenic potential. bitumen emissions, generated upon heating, may contain two-ring to seven-ring pahs, several of which are mutagenic and carcinogenic (iarc, 2011). in mammalian cells, exposure to bitumen emissions or their condensates produced mutagenic intermediates and dna adducts. analysis of the sample from mile 2 contains wide spectrum of pahs (figure 3). in the sample, 37 pahs have been found, with hexadecane showing a higher percentage of 6.56%, others like phenanthrene, naphthalene and its derivatives show lower percentage. the united states environmental protection agency (usepa, 2000), ranked sixteen pahs as priority in relation to health and the environment: naphthalene (na), acenaphthalene (ac), acenaphthene (ace), fluorene (flu), phenanthrene (ph), anthracene (an), pyrene (py), chrysene (ch), fluoranthene (fl), benzo [a] anthracene (baa), benzo [b] fluoranthene (bbf), benzo [k] fluoranthene (bkf), benzo [a] pyrene (bap), dibenzo [a, h] anthracene (da), benzo ademila o. & ojo f.g. ejssd, v 5 (2), 2018 78 © adama science & technology university https://ejssd.astu.edu.et [g, h, i] perylene (bpe) and indeno [1,2,3-c, d] pyrene (ip). possible long-term damage caused by chronic health hazard has diverted more attention to pahs. according to who (1998), apart from pahs, several other substances potentially harmful to health are asphaltenes, straight and branched aliphatic hydrocarbons, naphthene aromatics and resins. from the analysis of agbabu bitumen sample, duodecane, ethyl ester shows a wide spectrum (fig. 4) and the presence of benzene (target) ranged from 1.16 to 2.57%. spectrum of pahs values of bitumen sample collected at mulekangbo is shown in fig. 5. the result of pahs from bitumen sample collected at mulekangbo indicates higher amount of pyrene, and a considerable high amount of the entire target pahs like chrysene, fluorene, anthracene, phenanthrene, triphenylene and fluoranthrene, but triphenylene, benz [a] anthracene, and cyclohexane are negligible. the effects of pahs present in mulekangbo bitumen sample are considered to have carcinogenic and/or mutagenic potential. exposure to these compounds through inhalation or even absorption through the skin during application to streets and roads can cause skin cancer (gasthauer et al., 2007). the emissions generated during the production and application of the bitumen from this location would pose health and environmental risk to those involved. also, these pahs can leach into the environment through the degradation of the road surface and contaminate water bodies. when bitumen is applied during mixing in asphalt binders, it is usually handled at elevated temperatures, so trace amounts of pahs may occur in the hot bitumen fume and cause cancers risk to the workers handling the mixing. figure 3. spectrum of pahs values of bitumen sample collected at mile 2. ademila o. & ojo f.g. ejssd, v 5 (2), 2018 79 © adama science & technology university https://ejssd.astu.edu.et figure 4. spectrum of pahs values of bitumen sample collected at agbabu. figure 5. spectrum of pahs values of bitumen sample collected at mulekangbo 6. conclusion the engineering and chemical properties of natural bitumen samples collected from agbabu and its environs have been determined using standard methods. the water content of bitumen ademila o. & ojo f.g. ejssd, v 5 (2), 2018 80 © adama science & technology university https://ejssd.astu.edu.et and loss on heating of the samples in the locations are greater than the recommended values of 0.2% and 1 max respectively. the specific gravity of the samples is below the standard value of 1.01 for bitumen of good grade. from the penetration values, the bitumen are classified into two grades. agbabu and mulekangbo bitumen samples are classified as temperature susceptible bitumen while, mile 2 (sample a and b) are classified as conventional paving bitumen. mile 2 bitumen can be applied successfully in road construction in the tropics, but this can only be achieved after they must have been upgraded. the aas test carried out showed that agbabu, mile 2 and mulekangbo have a low concentration of heavy metals except for the high concentration of iron. however, low concentrations of lead and nickel in all the samples may pose environmental hazard and catalytic poisons during the refining of the bitumen. the gcms revealed high percentage of pahs in the bitumen sample collected from mulekangbo and the targets pahs like pyrene, anthracene, fluorene, etc. are carcinogenic and mutagenic in nature. exposure to these target pahs during application to streets and roads through inhalation and absorption through the skin tend to pose health hazards. therefore, exploitation of mulekangbo bitumen must undergo the primary bitumen refining process “distillation” in order to remove the pahs from the bitumen. the percentage of targets pahs like naphthalene in the samples collected from agbabu and mile 2 are low with no pyrene, anthracene and fluorene. thus, agbabu and mile 2 bitumen would have no impact on health and the environment during exploitation and utilization. this study recommends standard exploration and clean technology (distillation) during refining process to remove hazardous pahs from the bitumen. reference adebiyi, f.m., omole, a.a., (2007). organic, chemical and elemental characterization of components of nigerian bituminous sands bitumen. energy sources. part a: recovery, utilization and environmental effects, 29(8), 669-676. adegoke, o.s., ako, b.d., enu, e.i., (1980). geotechnical investigation of the ondo state bituminous sands. geology and reserves estimate. geological consultancy unit, department of geology, obafemi awolowo university, ile-ife. 1: 56. astm d5-97 (1998). standard test method for penetration of bituminous materials. annual book of astm standards, volume 04.03, american society for testing and materials, philadelphia 19103-1187. astm d92-01 (2001). standard test method for flash and fire points by cleveland open cup, astm, international, west conshohocken, pa, www.astm.org http://www.astm.org/ ademila o. & ojo f.g. ejssd, v 5 (2), 2018 81 © adama science & technology university https://ejssd.astu.edu.et bakare, h.o., esan, a.o., olabemiwo, o.m., (2015). characterisation of agbabu natural bitumen and its fractions using fourier transform infrared spectrometry. journal of chemistry and materials research, 7(8), 1-11. eurobitumen and asphalt institute, (2015). the bitumen industry – a global perspective, 3rd edition, eurobitumen and asphalt institute, isbn 978-1-93415473-1. federal ministry of solid minerals development (fmsmd), (2006). technical overview in nigeria’s bitumen belt and development potential. report: federal ministry of solid minerals development, abuja, nigeria, 1-14. gasthauer, e., maze, m., marchand, j.p., amouroux, j., (2007). characterization of asphalt fumes composition by gc/ms and effect of temperature. fuel, 87, 14281434. guma, t.n., madakson, p.b., yawas, d.s., aku, s.y., (2012). assessment of physicochemical properties of some bitumen from nigerian resources. nigerian journal of basic and applied science, 20(2), 177-181. hein, f.j., leckie, d., larter, s.r., suter, j.r., (2013). heavy oil and bitumen petroleum systems in alberta and beyond: the future is non-conventional and the future is now. aapg studies in geology, 64, 1-21. international agency for research on cancer (iarc) (2011). monographs on bitumen and bitumen emissions and some heterocyclic polycyclic aromatic hydrocarbons, 12. international programme on chemical safety (ipcs) (2004). concise international chemical assessment document 59: asphalt (bitumen). geneva, switzerland: world health organization. ipinmoroti, k.o., aiyesanmi, a.f., (2001). trace metals in the bituminous sands of ondo state, nigeria. nigerian journal of science, 35, 63-68. jones, h.a., hockey, r.d., (1964). the geology of part of southwestern nigeria. geological survey of nigeria (gsn) bulletin, 31: 101. lopes, j.l., (2008). riscos para a saude de trabalhadores de pavimentacao com asfalto. revista de gestao integrada em saude do trabalho e meio ambiente. sao paulo. lurgi, r., (1987). distillation test on tar sand from ondo state, nigeria. essen, 1-8. meyer, r.f., attanasi, e.d., freeman, p.a., (2007). heavy oil and natural bitumen resources in geological basins of the world: u.s. geological survey open-file report 2007-1084. http://www.pubs.usgs.gov/of/2007/1084. nassar, i.m., kabel, k.i., ibrahim, i.m., (2012). evaluation of the effect of waste polystyrene on performance of asphalt binder. arpn journal of science and technology, 2(10), 927-935. omatsola, m.a., adegoke, o.s., (1981). tectonic evolution and cretaceous stratigraphy of the dahomey basin. journal of mining and geology, 18(1), 130137. http://www.pubs.usgs.gov/of/2007/1084 ademila o. & ojo f.g. ejssd, v 5 (2), 2018 82 © adama science & technology university https://ejssd.astu.edu.et read, j., whiteoak, d., (2003). the shell bitumen handbook, fifth edition; hunter, r. n., ed., thomas telford: london. speight, j.g., (2000). asphalt. in: kirk-othmer encyclopedia of chemical technology. new york, usa: john wiley and sons, inc., 1-33. unep and ilo, (2004). concise international chemical assessment document 59, published under the joint sponsorship of the united nations environment programme, the international labour organization and world health organization, geneva, switzerland. united state environmental protection agency (2000). hot mix asphalt plants – emission assessment report, 454/r-00-019. united state environmental protection agency, (2007). integrated risk information system (iris) on polycyclic organic matter. http://www.epa.gov/iris. world health organization (who) (1998). selected non-heterocyclic polycyclic aromatic hydrocarbons. international programme on chemical safety, environmental health criteria 202, geneva. http://www.epa.gov/iris 35 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper production of bacterial keratinase using keratinous waste substrate yimeslal atnafu sima  , ameha kebede, misrak kebede school of biological sciences and biotechnology, college of natural and computational sciences, haramaya university, ethiopia, p. o. box 138, dire dawa, ethiopia article info abstract article history: received 02 august 2020 received in revised form 29 september 2020 accepted 14 november 2020 this study was conducted with the aim of isolation of efficient keratinase producing bacteria from the soils of chicken feather and human hair-dumping places, determining optimum keratinase production conditions and partially characterizing the stability of keratinase interms of keratinase activity assay with regards to some physicochemical parameters. inoculation of soil sample suspensions on chicken feather and human hair modified meal agar plate resulted in the growth of three keratinolytic bacterial isolates (kf1and kf2 from chicken feather and kh from hair cut dumping sites). these isolates were identified as bacillus species on the basis of their biochemical characteristics. the optimum temperature of keratinase production for all isolates was recorded at 60°c with activities of 16.2 u/ml/min, 15.5u/ml/min and 12.3 u/ml/min for isolates kf1, kf2 and kh, respectively. in all cases, ph 7 was optimum for keratinase production resulting in activities corresponding to 16.4 u/ml/min, 15.1u/ml/min and 12.4/ml/min for kf1, kf2 and kh, respectively. among the various carbon sources tested, potato gave 14.3 u/ml/min, 11.3 u/ml/min and 10.1u/ml/min for isolates kf1, kf2, and kh, respectively. regarding nitrogen sources, yeast extract gave 25.2 u/ml/min, 20.5 u/ml/min and 16.37 u/ml/min for kf1, kf2, and kh, respectively. studies on the effect of ph on the activity and stability of keratinase enzyme revealed that the crude enzyme had a maximum stability at ph 7.the maximum keratinase stability time for the three isolates was found to be 48 hr with keratinase activity of 8.5 u/ml/min, 6.5 u/ml/min and 5.9 u/ml/min for kf1, kf2, and kh, respectively. these results generally indicate that the keratinase obtained in this study belongs to the class of hydrolases that are active and stable at ph 7. thus, identification of the three bacillus isolates at a molecular level and separation and identification of the types of keratinase produced by molecular techniques is recommended. keywords: bacillus hydrolase keratin keratinase production physico-chemical parameters 1. introduction keratinase is an enzyme capable of degrading the insoluble structural protein called keratin. keratin is a fibrous structural protein of hair, nails, horn, hoofs, wool, feathers, and of the epithelial cells in the outermost layers of the skin (cai et al., 2008). keratin present in feathers and human hair cannot be degraded by the usual proteolytic enzymes such as trypsin, pepsin and papain. this is because of the differences in  corresponding author, e-mail: yimeslala@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.185 composition and molecular conformation of the amino acids found in keratin (janaranjani et al., 2015). keratinase enzymes are useful in the bio-conversion of keratin waste to feed and fertilizers. other promising applications of keratinolytic enzymes include enzymatic deharing in leather and cosmetic industry, and detergent uses. http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021................ yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 36 animal wastes can be used as a powerful nutrient source. but wastes like feathers and hair obtained as byproducts of meat and dairy processing cannot be degraded easily and hence they form a source of pollution. there are certain strains of microorganisms which produce extracellular enzymes which can serve as a substantial source of keratinase for the degradation of keratinous wastes (adriano and brandelli, 2007). animal wastes can be used as a powerful nutrient source. but wastes like feathers and hair obtained as byproducts of meat and dairy processing cannot be degraded easily and hence they form a source of pollution. there are certain strains of microorganisms which produce extracellular enzymes which can serve as a substantial source of keratinase for the degradation of keratinous wastes (andriano et al., 2007). in recent years, feather-treated with microbial keratinase is attracting wide attention with several applications. keratinase–treated feather is considered as a viable source of dietary protein in food and feed supplements, as the enzyme-treated end product is thought to retain high nutritive value. keratinases are projected to generate a potential worldwide market similar to other proteases having a price of 4.34 dollars (manoj et al., 2016). keratinolytic enzymes have several current and potential applications in agro industrial, pharmaceutical, and biomedical fields. their use in biomass conversion into biofuels may address the increasing concern on energy conservation and recycling (andriano et al., 2007). in ethiopia, isolation of protease was conducted by gessesse mula et al. (2011). this report described the isolation of bacillus species ar009 and b. pseudofirmus al-89 from an alkaline soda lake in ethiopia, rift valley area. the use of ‘nug’ meal as a low cost substrate for the production of alkaline protease was also described with the intent of practical application (genckkal, 2004). in recent years, limited efforts are also being made to improve the management of tannery waste in the local industries using protease. as concluded by gessesse mula et al. (2011), it is crucial to continue the efforts of searching for potent isolates in the environment because there are plenty of potential applications of keratinase in the food industry, animal feed processing and management of wastes of various industrial activities and municipal household garbage wastes. as the best knowledge of the author, there has been little work done on keratinase enzyme in ethiopia. therefore, this study was aimed to evaluate the in-vitro production of keratinase from bacterial species grown on keratineous wastes (chicken feather and human hair). 2. materials and methods 2.1. description of the study area the experiment was conducted in the microbiology laboratory of school of biological sciences and biotechnology at haramaya university, which is located at a latitude of 9° 26' n, the longitude of 42° 3' e, and an altitude of about 2010 meters above sea level. the area receives an average annual rainfall of 741.6 mm (ewonetu kebede, 2017). 2.2. research design the design of the research involved a laboratory based study of isolation, screening, biochemical characterization of bacterial isolates. the performance of bacterial isolates in terms of keratinase production was evaluated and stability of the activity of produced keratinase was done at various parameters. all experiments were conducted in triplicates and their values were recorded and used for subsequent analyses. 2.3. soil sample collection one hundred gram soil samples were collected from poultry feather and human hair cut dumping sites at haramaya university. the samples were collected using sterile plastic bags and stored in the refrigerator until used for isolation of bacteria. 2.4. preparation of feather and human hair cuts meal the feather and human hair cuts meal were prepared from native chicken feathers and human hair collected from poultry farm and barber’s shop at hu, respectively, as described by tork et al. (2008) with slight modifications. the feathers and human hair cuts were broken into smaller pieces of 2 cm long with scissors and washed several times with tap water. defatting of feather and hair pieces was done by soaking them in a mixture of chloroform: methanol (1:1) for 2 days followed by treatment with chloroform: acetone: methanol (4:1:3) solution for 2 days. the solvent was replaced every day. the feathers and hairs were finally washed several times with tap water to eliminate the solvent, dried for 24 hr in sunlight, ground using an electrically operated blender and used as feather and human hair cuts meal. https://www.ncbi.nlm.nih.gov/pubmed/?term=kumar%20m%5bauthor%5d&cauthor=true&cauthor_uid=28330246 yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 37 2.5. isolation, screening and identification of keratinase producing bacteria 2.5.1. isolation of bacteria from soil isolation of bacteria was performed by serial dilution and plating method on nutrient agar medium. one gram of soil sample was transferred to 10 ml of sterilized distilled water and mixed properly. serial dilution was made up to 10-6 and 0.1 ml was taken from10-6 of the diluted sample was inoculated to nutrient agar media by spread plate method. plates were incubated at 37ºc for 48 hr. the bacterial isolates were further sub cultured twice on nutrient agar media to obtain pure culture. pure isolates were maintained in nutrient agar slants at 4ºc for further studies. 2.5.2. screening of keratinase producing bacteria suspension of nutrient agar slant was made and about 0.1 ml of the pure culture of three isolate was uniformly spread plated on the surface of an agar medium supplemented with the prepared feather and human hair cuts meal as a sole carbon and nitrogen source. isolates obtained from poultry site soil was spread on agar supplemented with feather meal whereas isolates obtained from the soil samples collected from human hair cut dumping sites were spread on agar supplemented with human hair cuts meal. then colonies that appeared on the media were picked and subcultured on nutrient agar (harison and sandeep, 2014). the agar supplemeted with feather meal contained the following ingredients (g.l-1): nacl (0.5), kh2po4 (0.7), k2hpo4 (1.4), mgso4 (0.1) and feather meal (10). the agar supplemeted with human hair cuts meal contained all the above-listed ingredients except that the feather meal was replaced with human hair cuts meal. the ph of the medium was adjusted to 7. the plates were incubated at 37°c till the colonies appeared. the presence of keratinase producing bacteria was indicated by growth and formation of hallo zone forming colonies on modified chicken feather meal agar or on human hair cuts meal agar media. colonies on such media were subcultured and pure cultures were maintained on nutrient agar plate slants at 4°c (shabaan et al., 2014). 2.5.3. cultural, microscopic and biochemical characterization of the isolate the isolates were identified using: a) their cultural characteristics such as colony morphology with respect to shape, texture of colony and pigmentation b) microscopic observation of the isolates under the high power magnifying lens of the compound light microscope after gram staining. motility tests were also performed to observe the morphology and motility of the cells and biochemical characteristics as described in bergey’s manual of systematic bacteriology (sneath et al., 1986). the isolates were biochemically characterized using catalase, carbohydrate fermentation, oxidase, starch hydrolysis, indole production, methyl red, vogasproskauer, citrate utilization, triple sugar iron, nitrate reduction and amino acid utilization tests for the purpose of preliminary identification of the isolates. 2.6. production of crude keratinase using the bacterial isolates keratinase was produced by employing submerged fermentation using two types of sterile media. the first one was prepared from chicken feather meal (1%), yeast extract (0.01%), nacl (0.05%), kh2po4 (0.03%), k2hpo4 (0.04%) and mgcl2 (0.01%), at a ph of 7. the second media composed of human hair cuts meal (1%), yeast extract (0.01%), nacl (0.05%), kh2po4 (0.03%), k2hpo4 (0.04%) and mgcl2 (0.01%), at a ph of 7. these media were inoculated by 2-3 inocula taken from pure cultures of isolates and incubated for 3 days at 37ºc. after incubation, portions of the broth cultures were centrifuged at 10,000 rpm for 10 min and the supernatants were used as source of crude enzymes (lin and yin, 2010). the amount of keratinase was estimated using keratinolytic (keratinase) assay method described in section 2.7. 2.7. assay for keratinolytic activity the assay of keratinolytic activity was conducted by using soluble keratin as a substrate. soluble keratin was made by mixing separately 5 gm of chicken feather and 5 gm of the human hair cut with 250 ml of dimethylsulfoxide (dmso) and heating the obtained mixture in a reflux condenser at 100°c for 2 h. soluble keratin of each was precipitated by addition of chilled acetone at −20°c for 2 hr, followed by cooling and centrifugation at 10000 rpm for 10 min. the resulting precipitate was washed twice with distilled water and dried at 40ºc in a hot air oven. the keratin solution was prepared by dissolving 1gm of soluble keratin in 20 ml of 0.05 m naoh, adjusting the ph to 7 with 0.1 m hcl yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 38 and diluting the resulting solution to 200 ml with 0.05 m phosphate buffer ph 7 (vigneshwaran et al., 2010). the keratinolytic activity was assayed by the modified method of cheng et al. (1995) by incubating 1.0 ml of crude enzyme which was diluted in 0.05 m tris-hcl buffer (ph 7.0) with 1.0 ml of 1% soluble keratin solution at 50ºc in a water bath for 20 min. the reaction was stopped by adding 2.0 ml of 0.4 m trichloroacetic acid (tca). the precipitate formed by the addition of tca was removed by centrifugation at 10,000 rpm for 10 min. after centrifugation, 0.2 ml of the supernatant was taken and diluted with 1.0 ml of distilled water. to the resulting dilution, 5.0 ml of alkaline copper reagent was added, shaken well, and incubated for 10 min. after incubation, 0.5 ml of folin ciocalteau (fc) reagent was added and incubated again in the dark for 30 min to allow blue color development. the control was prepared by incubating enzyme solution with 2 ml of tca without the addition of keratin solution. the absorbance was measured at 660 nm using a uvspectrophotometer. one unit of alkaline keratinase was defined as the amount of enzyme required to liberate 1 μg of tyrosine per min per ml under the standard assay conditions (vigneshwaran et al., 2010). 2.8. effect of physico-chemical parameters on keratinase production 2.8.1. effect of ph, temperature, and concentration of substrate on keratinase production the effect of three different physicochemical parameters, i.e. ph, temperature, and concentration on keratinase production was assessed for the isolate. the effect of ph and temperature on keratinase production were individually tested by adjusting the production media to different ph values (ph 5, 6, 7, 8, 9 and 10) and incubating to varying temperatures (50°c, 60°c, 70°c,and 80°c). similarly, the effect of substrate concentration on the production of keratinase was assessed by growing the isolates in media containing different concentrations of feather and human hair meal as a substrate (2 mg/ml, 4 mg/ml, 6 mg/ml, 8 mg/ml and 10 mg/ml) were used. these fermentation media were assayed every day for keratinase production till a decline is observed in the enzyme activity (saibabu et al., 2013). 2.8.2. effect of carbon and nitrogen source on the production of keratinase separately, 5% of wheat flour, corn flour, sorghum flour, and potato were used as carbon source in place of glucose to find out their effect on keratinase production. the cultures were incubated at 37°c and ph 7 for 48 hr and the sources of carbon used in the production medium were varied by replacing glucose with the above-mentioned substrates (akcan, 2012) the effect of different nitrogen sources were tested by adding five gm of nitrogen-containing substrates such as tryptone, peptone, and yeast extract in the production medium separately. the fermentation media having the three isolates in different flask were incubated at 37oc and ph 7 for 48 hr and tested for keratinase production (venkata et al., 2013). 2.8.3. effect of ph, temperature and incubation time on keratinase activity the optimal ph for keratinase activity was determined over a ph range of 5, 6, 7, 8, 9, and 10. to determine the ph range over which keratinase remain stable, the crude enzyme was pre-incubated in buffers over a ph range of 5, 6, 7, 8, 9 and 10 at 50°c for 60 min. citric acid/sodium phosphate buffer was used for ph between 5 and 7; barbital/hcl for ph between 8 and 9 and sodium carbonate buffer for ph between 10. to determine the thermo-stability, the enzymes were preincubated in barbital buffer (ph 7) at temperatures over the range of 50, 60, 70 and 80°c (minghai, 2012). the time required to attain the maximum enzymes activity was optimized for each isolate. to do this, each isolate was inoculated into chicken feather and human hair cuts meal media and incubated at 37°c. the keratinase activity was measured at regular intervals for 5 days (24 hr, 48 hr, 72 hr, 96 hr, and 120 hr). from the graph, the time required to attain the highest enzyme production was determined (anitha and eswari, 2012). 2.9. data analysis all data gathered in this study were subjected to statistical analysis using spss version 20. the degradability and enzyme activities were analyzed by taking the mean values of triplicates. microsoft office excels work sheet 2007 was used for the analysis of generated data and the preparation of graphs. yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 39 3. results 3.1. isolation. screening and cultural characterization of keratinase producing bacteria among the three bacterial isolates obtained, kf1 and kf2 were the isolates from the poultry farm site and kh was the isolate from human hair-dumping site. the isolates were able to grow on the modified human hair cut and feather meal agar plates. two isolates (kf1 and kf2) have circular, white and smooth texture. but for kh isolate the morphology of the colony was white darkish, oval shaped and its texture was smooth like that of the other isolates. all the three isolates (kf1, kf2 and kh) are gram positive and motile. 3.2. biochemical characterization the results of the biochemical tests of the three isolates i.e., kf1, kf2, and kh are summarized in table 1. 3.3. identification of keratinase producing bacterial isolate based on the cultural, microscopic and biochemical characteristics of the isolates, isolate kf1, kf2 and kh were identified as bacillus species. 3.4. production of keratinase using bacterial isolates the results of this study indicated that the activity of released keratinase from kf1, kf2, and kh isolates was 14.2±0. 45 u/ml/min, 11.9±0.35 u/ml/min, and 10. 9±0.34 u/ml/min, respectively (table 2). the highest and lowest keratinolytic activities were consistently recorded for isolates kf1 and kh, respectively. 3.5. effect of physico-chemical parameters on keratinase production 3.5.1. effect of ph on keratinase production the highest keratinase production was recorded for kf1 at ph 7 (showing a keratinase activity of 16.4 u/ml/min). the optimum keratinase production by kf2 and kh, at ph 7 was 15.1 u/ml/min and 12.3 u/ml/min, respectively. the lowest keratinase production of 4.5 u/ml/min, 4 u/ml/min, and 2.7 u/ml/min was recorded at ph 10 for kf1, kf2 and kh isolates, respectively (figure1). table 1: biochemical characterization of the bacterial isolates biochemical characteristics bacterial isolates kf1 kf2 kh catalase test + + + indole test citrate utilization test + + + starch hydrolysis test + + + oxidase test methyl red test h2s formation test(tsi) test + + slant color yellow (acid) yellow (acid ) bottom color red (alkali) red (alkali) red (alkali) lactose utilization test + carbohydrate fermentation test glucose + + + sucrose + + + lactose + (+) indicates positive result and (-) indicates negative result table 2: keratinolytic activity of keratinase produced by the isolate no. isolates activity u/ml/min 1 kf1 14.2±0.45 2 kf2 11.9±0.35 3 kh 10.9±0.34 4 cf 1.2±0.45 5 ch 1±0.26 yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 40 figure 1: effect of ph on enzyme production 3.5.2. effect of temperature on keratinase production the highest keratinase production was recorded at 60°c for kf1, kf2 and kh with an activity of 16.2 u/ml/min, 15.5 u/ml/min and 12.3 u/ml/min respectively. the lowest keratinase production was recorded for kf1, kf2 and kh at 80°c was 14.1, 13.2 and 8.7, respectively (figure 2). figure 1: effect of temperature on enzyme production 3.5.3. effect of concentration of substrates on keratinase production the highest keratinase production was recorded at 10 mg /ml of feather meal and human hair cut concentration (specific activities of 10.5, 8.5 and 5.5 u/ml/min for kf1, kf2 and kh, respectively). the lowest keratinase production was recorded at 2 mg/ml of feather meal and human hair concentration for all bacterial isolates (figure 3). figure 3: effect of feather and human hair cut concentration on keratinase production 3.5.4. effect of the type of carbon and nitrogen source on the production of keratinase the highest keratinase production was recorded with the addition of yeast extract for all isolates (with the activities of 25.2 u/ml/min, 20.5 u/ml/min and 16.4u/ml/min for kf1, kf2, and kh, respectively). the lowest keratinase production was recorded on maize (with specific activities of 7.9 u/ml/min for kf1 and kh; and 8.5u/ml/min for kf2) (figure 4). figure 4: effect and types of carbon and nitrogen source on keratinas production (nutrient) 25.2 23.2 18.9 7.9 12.1 14.5 9.3 20.5 18.8 14.3 8 11.1 12.2 7.9 16.3 15.4 8.3 7.9 8.4 10.1 8 0 5 10 15 20 25 30 kf1 kf2 kh 9.3 12.5 15.2 12.4 6.5 4.1 7.5 11.1 13.2 11.1 5.9 3.1 6.3 10.5 10.9 9.2 3.4 2.2 0 2 4 6 8 10 12 14 16 5 6 7 8 9 10 e n z y m e a c ti v it y ( u /m l/ m in ) ph kf1 kf2 kh 15.2 16.1 14.4 14.1 13.2 15.1 13.2 13.2 11 12.5 11.93 8.7 0 2 4 6 8 10 12 14 16 18 50 60 70 80 kf1 kf2 kh e n z y m e a c ti v it y ( u /m l/ m in ) temperature (°c) 4 5.1 6.93 8 10.5 9.7 2.5 3.6 4.7 6.5 7.5 5.3 3.5 4.5 5.4 7.6 9.1 8.4 0 2 4 6 8 10 12 2 4 6 8 10 12 kf1 kh kf2 e n z y m e a c ti v it y ( u /m l/ m in ) concentration (mg/ml) e n z y m e a c ti v it y ( u /m l/ m in ) yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 41 4. discussion 4.1. isolation, screening and identification of keratinase producing bacteria the study showed that kf1 and kf2 grew and formed a hallo zone on the feather meal agar plates and kh on the modified human hair cut. this happened because the isolates might be released extracellular keratinase which breaks down keratin and increases the amino acid (tyrosine) content of the medium. the cultural, microscopic and biochemical data for those keratinolytic bacteria that were isolated from poultry feather and human hair cut dumping sites indicated that the three isolates (kf1, kf2 and kh) belonged to the genus bacillus according to the descriptions provided in berge’s manual of systematic bacteriology (brenner et al., 2004). 4.2. effect of ph, temperature, and concentration of substrate on keratinase production in the present study keratin degradation in vitro was found to be associated with the release of a large amount of extracellular keratinase into the production medium by the grown isolates. the highest keratinase production was recorded for kf1 at ph 7. srivastava et al. (2011) reported ph 8.5 as optimum for keratinase production in bacillus spp. cheng et al. (1995) also reported the highest keratinase production by b. licheniform was obtained at initial ph of 8.5. similarly, b. megatherium was identified as a better alkalophilic keratinase producer by srivastava et al. (2011). the variation in keratinase production of the previous study may be due to bacterial species difference or other environmental factors. the highest keratinase production was recorded at 60°c for kf1, kf2 and kh. similarly, sivakumar et al. (2012) reported that keratinase enzyme activity for bacillus over a broad range of temperature (30-80°c) production is found to be optimal at 50°c. further increase in the temperature to 80°c reduces keratinase enzyme activity. laxman et al. (2004) also observed that the enzyme showed broad temperature specificity with a maximum activity at 60°c. the relative activity of enzyme was found to be higher in the temperature range of 50–70°c than at the normal assay temperature (40°c), while the enzyme retained nearly 50% of its activity at 80°c. the highest keratinase production was recorded at 10 mg/ml of feather and human hair cut meal. anitha and eswari (2012) reported that significant improvement in yield of keratinase was observed on the medium with 2% raw feather. keratinase production at the level of 0.5% feather meal was ten times less than that of 3% feather meal. this was because the amount of substrate supplied for growth and enzyme production was sufficient for the two isolates. kf1 and kf2 showed a higher keratinase production this is because of feather protein is an excellent source of metabolizable protein (klemersrud et al., 1998), and microbial keratinases enhance the digestibility of feather keratin (lee et al., 1991; odetellah et al., 2003; korniłłowicz-kowalska and bohacz, 2011). 4.3. effect of the type of carbon and nitrogen source on the production of keratinase the three isolates showed the highest keratinase production by using yeast extract substrate as a nutrient. in previous study, supplementation of yeast extract resulted in maximal keratinase production by stenotrophomonas sp (ramnani and gupta, 2004). some cost effective substrate such as soybean meal have been successfully used for keratinase production (vidyasagar et al., 2007). different bacteria have different preference for either organic or inorganic nitrogen for growth and enzyme production although complex nitrogen sources are usually used for alkaline protease production (panday et al., 2000). the choice of carbon and nitrogen sources has a major influence on the maximum yield of enzymes. highest keratin hydrolyzing activity was achieved at higher yeast extract concentrations in a shorter period than in the presence of lower yeast extract concentrations (prakasham et al., 2006). sivakumar et al. (2012) also reported that the activity of crude keratinase assessed by incubating keratinase with different carbon and nitrogen sources. extra nitrogen (yeast extract) have positive effects on keratinase production while other carbon and nitrogen sources have negative effects. 5. conclusion keratinase is one of the most important groups of industrial enzymes with considerable application in the animal feed processing leather industry, medical activity, beverage industry and others sectors. in this yimeslal atnafu et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 42 study, kf1, kf2 and kh keratinolytic bacterial isolates that belong to bacillus genus were identified by cultural, microscopic and biochemical characterization. the isolates produced maximum keratinase at ph 7, 60°c and 48 hours fermentation conditions. the study showed that maximum keratinase production was obtained from the use of potato as carbon source and yeast extract as nitrogen source. generally the three bacterial isolates kf1 and kf2 isolated from soil of poultry site and kh from human hair cut damp sites are efficient in the production of the keratinase enzyme. identification of the three bacillus isolates at a molecular level, and purification and identification of the types of keratinase is recommended. acknowledgment i would like to express my sincere appreciation to haramaya university post graduate program directorate, biology department for funding the work. thanks also go to all who participated directly or indirectly for the successful accomplishment of this work. reference adriano, b. 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(1986). .bergey’s manual of systematic bacteriology, vol. 2 baltimore., williams and wilkins. srivastava a., sharma, a. & suneetha, v. (2011). feather waste biodegradation as a source of amino acid. european journal of experimental biology, 1(2): 56-63 venkata, s., francois, n.., niyonzima. & sunil, s. (2013). isolation, partial purification and characterization of keratinase from bacillus megaterium. international research journal of biological sciences, 2(2):13-20. vigneshwaran, c; shanmugam, s., & kumar,t. s. (2010). screening and characterization of keratinase from bacilluslicheniformisisolated from namakkal poultry farm. researcher, 2(4): 89-96. 21 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper chemical constituents and anti-proliferative activity of resin of c. sphaerocarpa against four human cancer cell lines worku dinku1, sang un choi2, sang-ho lee2, young-sik jung2, aman dekebo1,  1department of applied chemistry, school of applied natural science, adama science and technology university, p. o. box 1888, adama, ethiopia 2bio and drug discovery division, korea research institute of chemical technology, republic of korea article info abstract article history: received 1 february 2020 received in revised form 14 march 2020 accepted 24 march 2020 myrrh, a resin derived from the commiphora genus, has traditionally been used for treatment of various human diseases, such as amenorrhea, ache, tumors, fever, and stomach pains. despite widespread traditional medicinal use, the pharmacological activity and chemical composition of many commiphora species are not well known. the current study pursues to evaluate the cytotoxicity activity of the n-hexane and chloroform fractions of c. sphaerocarpa. both the anti-proliferative effect and chemical compositions were correlated. the compositions of the chemical constituents were analyzed by gas chromatography coupled to mass spectrometry (gc-ms). the in vitro cytotoxicity activity of crude extracts were evaluated in cellular lines of non-small cell lung cancer a549, ovarian cancer a2780, pancreatic cancer mia-paca-2, and stomach cancer snu-638 by srb assay. the n-hexane fraction showed better apparent cytotoxicity on a549, a2780, and snu-638 cancer cell lines with ic50value ranging from 9.62 μg/ml to 10.30 μg/ml with dose-dependent relationship in vitro compared to the chloroform fraction. this efficacy might be correlated with the presence of pentacyclic triterpenes such as lupeol, urs-12-en-3-one, -amyrin, -amyrin, and sesquiterpenes: -copaene, caryophyllene, humulene, alloaromadendrene, -muurolene, selinene, -humulene and caryophyllene oxides in resin of the plant. our findings indicated components of n-hexane fraction of c. sphaerocarpa might be useful to treat aforementioned selected cancers after further studies. keywords: anti-proliferative activity commiphora sphaerocarpa gc-ms ovarian cancer pancreatic cancer stomach cancer srb assay 1. introduction cancer, a cellular malignancy that results in the loss of normal cell-cycle control, such as unregulated growth the lack of differentiation, can develop in any tissue of any organ, at any time (chang and kinghorn, 2001). the global cancer burden was estimated 18.1 million new cases and 9.6 million deaths in 2018. cancers of the lung, female breast, and colorectal cancer are the top three cancer types in terms of incidence, are ranked within the top five in terms of mortality (first, fifth, and  corresponding author, e-mail: amandekeb@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.194 second, respectively). together, these three cancer types are responsible for one third of the cancer incidence mortality burden worldwide (bray et al., 2018). in ethiopia, cancer has become the second leading cause of death next to cardiovascular diseases in the adult population (memirie et al., 2018). the most common adult cancers were: cancers of the breast cervix, colorectal cancer, non-hodgkin lymphoma, leukemia, cancers of the prostate, thyroid, lung, stomach, and liver (memirie et al., http://www.ejssd.astu.edu/ mailto:amandekeb@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx worku dinku et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 22 2018). natural products have proven to be an important source of anticancer drugs (cragg and newman, 2005), identification of phytochemical cytotoxic entities that are effective against a range of cancer cell lines, less active or non-toxic against the normal cell population is an effective method for selection of fractions. the genus commiphora (burseraceae) comprises over 150 species, most of which are confined to eastern africa, with few species also occurring in southern arabia, india and south america (shen et al. , 2012; shen and lou, 2008; xu et al., 2011). according to soromessa et al. (2013), south east lowland of ethiopia is characterized by its high diversity of acacia and commiphora species and the same study revealed that out of total species in the genus commiphora about half of them are endemic to the small area of south eastern ethiopia, north eastern kenya and somalia. over 50 commiphora species are known to occur in ethiopia, of which 14 (25%) species are endemic (vollesen et al., 1989). the resin of c. sphaerocarpa is sold under the product name myrrh. ethnobotanical notes on herbarium specimens of commiphora species deposited at the national herbarium in addis ababa university also revealed various traditional uses of resins by different communities in ethiopia. for example, the resin of c. sphaerocarpa is used against cough, diarrhea, headache, and against ticks of cattle. additionally, the note indicated fruits of this plant are edible. this resin is sometimes found in true myrrh as adulterants. previous study revealed that petroleum ether extract of c. sphaerocarpa afforded six sesquiterpenes of which one of them i.e. (1e)-8,12epoxygermacra-1,7,10,11-tetraen-6-one was novel (dekebo et al, 2002). we hereby report chemical composition of n-hexane fraction of c. sphaerocarpa which was analyzed by gc-ms along with anticancer activity of crude methanol extracts, n-hexane, and chloroform fractions, obtained by liquid-liquid partitioning from methanol extracts, against four human cancer cell lines: a549, a2780, mia-paca-2 and snu638 using srb assay under in vitro conditions. 2. materials and methods 2.1. plant material collection resin of c. sphaerocarpa chiov (burseraceae) and other botanical specimens were collected from sof omar bale zone, oromia regional state, ethiopia in october, 2016. the specimens have been identified by botanist shambel alemu and deposited at the national herbarium, biology department, addis ababa university, ethiopia (voucher number: 072820). 2.2. extraction and liquid-liquid fractionation the resin sample was air dried left under shadow till experimental work. the powdered resin of c. sphaerocarpa (95.1 g) was extracted with methanol (1 l x 3) for three days at 25°c. the crude methanolic extract was evaporated under vacuum to afford a yellow solid (34.8 g, 36.6%) which was then suspended in water (500 ml) and successively partitioned with nhexane (500 ml x 3) followed by chloroform (500 ml x 3) to afford 12.1 g (34.8%) and 2.5 g (7.1%) yields for n-hexane and chloroform fractions, respectively. 2.3. gc-ms analysis of n-hexane fraction gc-ms analysis was done by using a gc (7890b, agilent technologies, usa) coupled with an ms (5977a network, agilent technologies). the gc had an hp 5ms column (non-polar column, agilent technologies), 30 m × 250 μm internal diameter (i.d.) 0.25 μm film thickness. the carrier gas was helium flowing at a rate of 1 ml/ min. the injector temperature was 230°c and the injection mode was split mode with split ratio 4:1. the initial oven temperature was 40°c held for 3 min. it was raised to 70°c at 4°c/min held at this temperature for 3 min. the oven temperature was then raised 80°c at 1°c/min with no holding time, 100°c at 4°c/min with no holding time then to 180°c at 10°c/min, then with no holding time 20°c/min until it reached 280°c held at this temperature for 2 min. the total runtime was 60 min. mass spectra were recorded in ei mode at 70 ev, scanning the 33-500 m/z range. the identification of the volatile compounds was performed by comparing the mass spectra of the compounds with those in the database of nist11 and literature data. 2.4. anti-proliferative assessment the cancer cell lines including the human non-small cell lung cancer cell line (a549), ovarian cancer cell line (a2780), pancreatic cancer cell line (mia-paca-2) stomach cancer cell line (snu-638) were used for evaluation of anticancer activity. all cell lines were maintained using rpmi1640 cell growth medium (gibco, carlsbad, ca), supplemented with 5% fetal worku dinku et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 23 bovine serum (fbs) (gibco), grown at 37°c in a humidified atmosphere containing 5% co2. the cytotoxicity of the crude methanol extract its organic solvent fractions of the plant against cultured human tumor cell lines were evaluated on the already developed sulforhodamine b (srb) method (schols et al., 1988). 2.5. treatment of cell lines stock solutions of the crude meoh extract, n-hexane and chloroform fractions dissolved in dmso were prepared in the corresponding medium at different concentrations of 0.1, 0.3, 1.0, 3.0, 10.0 and 30 μg/ml to determine percentage of growth inhibition the and for the 50% growth inhibition (ic50). each tumor cell line was inoculated over standard 96-well flat-bottom micro plates then incubated for 24 h at 37°c in a humidified atmosphere of 5% co2. the attached cells were then incubated with serially diluted each samples. after continuous exposure to the compounds for 72 h, the culture medium was removed from each well and the cells were fixed with 10% cold trichloroacetic acid at 4°c for 1 h. after washing with tap water, the cells were stained with 0.4% srb dye incubated for 30 min at room temperature. the cells were washed again and then, the cell bound srb was solubilized with 10 mm buffered tris base solution of ph 10.5. the absorbance was measured spectrophotometrically at 520 nm with a micro titer plate reader. each experiment was conducted in triplicate. the ic50 values of crude meoh extract and fractions were calculated by the nonlinear regression analysis. the ic50 was expressed as the concentration of drug reducing the plaque number by 50% as compared to mock-treated controls. it was calculated from a dose– response line obtained by plotting the percentage plaque reduction, with respect to the control plaque count, versus the logarithm of compound dose. triplicate wells were utilized for each drug concentration tested. 3. result and discussion analysis of n-hexane fraction comprised of 38 components among which 23 constituents were identified (figure 1 and table 1). pentacyclic triterpenes were the major compounds with a high content of which, 1: (1s,6r,9s)-5,5,9,10-tetramethyltricyclo[7.3.0.0(1,6)]dodec10(11)-ene, 2: 2(1h)naphthalenone, 3,5,6,7,8,8ahexahydro-4,8a-dimethyl-6-(1-methylethenyl)-, 3: amyrin (13.42 %), 4: urs-12-en-3-one (14.39%), 5: lupeol (15.91%), 6: hop-22(29)-en-3.β-ol (7.89%) and 7: -amyrin (10.96 %) (figure 2). terpenoids have been previously reported to show antimicrobial activity (field and lettingam 1992). for example, β-amyrin has been shown to exhibit various pharmacological activities in vitro and in vivo against inflammation, microbial, fungal, viral infections and cancer cells (vázquez et al., 2012). sesquiterpene hydrocarbons such as -copaene (1.16%), caryophyllene (0.96%), humulene (0.12%), alloaromadendrene (0.12%), -muurolene (0.03%), selinene (0.12%), -humulene (0.04%) and oxygenated sesquiterpene caryophyllene oxide (0.50%) were found as minor constituents in the n-hexane fraction (table 1). figure 1: gc of n-hexane fraction of c. sphaerocarpa, 1: (1s,6r,9s)-5,5,9,10-tetramethyltricyclo [7.3.0.0(1,6)] dodec10(11)-ene, 2: 2(1h)naphthalenone, 3,5,6,7,8,8a-hexahydro-4,8a-dimethyl-6-(1-methylethenyl)-, 3: -amyrin (13.42 %), 4: urs-12-en-3-one (14.39%), 5: lupeol (15.91%), 6: hop-22(29)-en-3.-ol (7.89%) 7: -amyrin (10.96 %). worku dinku et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 24 table 1: compounds identified in the n-hexane fraction of c. sphaerocarpa and their percentage area name of compounds a rt mol.wt mol. formula % composition copaene 21.1 204.19 c15h24 1.16 caryophyllene 22.0 204.19 c15h24 0.96 humulene 22.7 204.19 c15h24 0.12 alloaromadendrene 22.9 204.19 c15h24 0.12 uurolene 23.2 204.19 c15h24 0.03 selinene 23.3 204.19 c15h24 0.12 umulene 23.4 204.19 c15h24 0.04 α-amorphene 23.9 204.19 c15h24 0.03 panasinsen 24.0 204.19 c15h24 0.12 cadinene 24.1 204.19 c15h24 0.18 caryophyllene oxide 25.3 220.18 c15h24o 0.50 (+)-epi-bicyclosesquiphellrene 26.4 204.19 c15h24 0.07 (1s,6r,9s)-5,5,9,10-tetramethyltricyclo[7.3.0.0(1,6)]dodec10(11)-ene (1) 39.2 218.20 c16h26 9.59 2(1h)naphthalenone, 3,5,6,7,8,8a-hexahydro-4,8a-dimethyl6-(1-methylethenyl)(2) 39.3 218.17 c15h22o 4.83 olean-12-ene 40.3 410.39 c30h50 1.23 olean-12-en-3-one 40.4 424.37 c30h48o 2.39 .-amyrin (3) 42.0 426.39 c30h50o 13.45 urs-12-en-3-one (4) 42.3 426.39 c30h50o 14.39 lupeol (5) 43.0 426.39 c30h50o 15.91 hop-22(29)-en-3 -ol (6) 43.1 426.39 c30h50o 7.89 amyrin (7) 43.8 426.38 c30h48o 10.96 taraxasterol 44.2 426.39 c30h50o 3.72 a'-neogammacer-22(29)-en-3-one 48.1 424.37 c30h48o 0.34 a compounds listed in order of elution from a hp 5ms column; rt = retention time; mol.wt = molecular weight; mol. formula = molecular formula. figure 2: structures of some major compounds identified in n-hexane fraction of the resin of c. sphaerocarpa worku dinku et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 25 gc-ms analysis results indicated that -amyrin had a shorter retention time than -amyrin (table 1) which was consistent with the earlier reports (burnoufradosevich et al., 1985). some constituents such as copaene, -humulene, -selinene, and -cadinene were identified in our previous study from the essential oil of c. sphaerocarpa resin (dekebo et al., 2002). sesquiterpenes, which are one of the most common terpenes, are a class of natural products with a diverse range of attractive industrial properties (wang et al., 2011; scalcinati et al., 2012). several biological activities are attributed to sesquiterpenes, such as antimicrobial (wu et al., 2012), antibacterial (stojanović-radić et al., 2012) antioxidant, antifungal (al-maskri et al., 2011; conforti et al., 2008) and antigenotoxic (anter et al., 2011) activities. nishida et al. (2000) reported that -copaene is not genotoxic and it increases the antioxidant capacity in human lymphocyte cultures. fernandes et al., (2007) reported pronounced oral anti-inflammatory effects for the sesquiterpenes isolated from the essential oil of cordia verbenacea. their oral anti-inflammatory properties are probably related to an important inhibition of the activation and/or release of different inflammatory mediators such as bradykinin, platelet activating factor, histamine, il-1β, tnfα and pge2. the antiinflammatory effects of these compounds seem to be closely associated with their ability to inhibit the upregulation of both cox-2 and inos enzymes. these workers suggest that sesquiterpenes isolated from the essential oil of c. verbenacea, α-humulene and (−)trans-caryophyllene, might constitute a relevant therapeutic alternative for the treatment of inflammatory diseases (fernandes et al., 2007). in vivo disease resistance assays, using zmtps21 and zmtps21 nearisogenic lines, supported the endogenous antifungal role of selinene-derived metabolites involved in the biosynthesis of nonvolatile antibiotics, zmtps21 exists as a useful gene for germplasm improvement programs targeting optimized biotic stress resistance (ding et al., 2017). the concentrations of crude methanol extract which inhibit 50% of cell growth (ic50) was found to be less than 30 g/ml (table 2, figure 3a) against most of the cancer cell lines tested, which is within the limit of criteria set by the american national cancer institute for further purification (radovanovic, 2015). our antiproliferative activity data indicated that the crude extract and fractions are far less than etoposide (figure 3d). the n-hexane fraction (table 2, figure 3b) showed better anti-proliferative activity than the crude methanol extract and chcl3 fractions (table 2, figure 3c) against all cell lines tested. the chloroform fraction has comparable activity to that of the crude methanol extract (figures 3a and 3c). the n-hexane fraction showed apparent bioactivities on a549, a2780, and snu-638 cancer cell lines with ic50 value ranging from 9.62 μg/ml to 10.30 μg/ml with dose-dependent relationship in vitro (figure 3b and table 2). these results suggest that n-hexane fraction is responsible for the observed high anti-proliferative activity. the cytotoxicity of c. sphaerocarpa crude methanol extract, n-hexane and chloroform fractions have not been studied before, but the cytotoxicity of some compounds identified in the n-hexane fraction extracted from a variety of plant species showed different pharmacological activities. in vivo studies have identified that lupane type pentacyclic triterpenoid have strong antitumor and anti-inflammatory effects (saleem, 2009). experimental results showed that, in the mouse skin carcinogenesis model, local application of lupeol for 28 weeks can inhibit the growth of tumor prolongs the latency of tumor cells. the mechanism might be related to the nuclear factor kappab (nf-κb)/phosphatidylinositol 3-kinase (pi3k)/proteinkinase b (akt) signaling pathway (saleem et al., 2004). aratanechemuge et al (2004), reported that hypodiploid apoptotic peak can be detected after the lupane type pentacyclic triterpenoid treatment on hl-60 leukemia cells, with time-dose-dependency (aratanechemuge et al., 2004). gallo and sarachine (2009) reviewed that lupeol and some of its analogues have been shown to possess a wide range of biological activities such as anti-cancer, hepatoprotective, antimicrobial, cardioprotective, anti-melanoma, etc. therefore, lupeol and its derivatives have a potential to be consumed as a dietery supplement to prevent cancer, coronary and hepatic disease. though, the sesquiterpenes such as caryophyllene and caryophyllene oxide found in trace amount in nhexane fraction, essential oils or fractions with high amount of the sesquiterpenes possessed higher cytotoxic activity against animal human tumor cells (el hadri et https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr52 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr39 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr55 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr41 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr2 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr9 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4082788/#cr4 worku dinku et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 26 a07-me [ g/ml] 0.1 0.3 1.0 3.0 10.0 30.0 n e t g r o w th a s % o f c o n tr o l -50 0 50 100 a549 a2780 mia-paca-2 snu638 a07-ch [ g/ml] 0.1 0.3 1.0 3.0 10.0 30.0 n e t g r o w th a s % o f c o n tr o l -50 0 50 100 a549 a2780 mia-paca-2 snu638 al., 2010). the sesquiterpene hydrocarbon caryophyllene and its corresponding oxygenated sesquiterpene caryophyllene oxide showed anti-inflammatory effect on lps induced paw edema rat with a mechanism of action by reduction of neutrophil migration inhibition of nf-κb (medeiros et al., 2007) and inhibition of 5-lox catalyzed leukotrienes rat (jin et al., 2011). the study reported by da silva et al. (2016) has shown that nhexane extract of i. coccinea flowers led to the isolation of a mixture of α and β-amyrin. the mixture was found to be moderately cytotoxic towards b16-f10 and hepg2 cancer cell line with ic50 23.21 and 24.09 µg/ml, respectively, and non-cytotoxic with ic50> 25 µg/ml against hl60, k562 and pbmc cancer cell lines (da silva et al., 2016). the mixture of and -amyrin from protium heptaphyllum demonstrated peripheral and central analgesic effects independent of the opioid system, and also showed a potent anti-inflammatory activity. the anti-inflammatory activity was potentiated by both indomethacin and thalidomide, suggesting a potential involvement of prostaglandins and tnf-alpha inhibitions (aragao et al, 2008). urs-12-en-3-one,(3β)27-[(z)-feruloyloxy]-3-hydroxyurs-12-en-28-oic acid reported form the stem bark of plumeria obtusa showed anti-mutagenic activity (siddiqui et al., 2004). in conclusion, our results for the n-hexane fraction revealed moderate cytotoxic activity, which might be attributed to the presence of pentacyclic triterpenes and sesquiterpenes. the cytotoxicity to the three cancer cell lines by the n-hexane fraction needs further research on the underlying molecular mechanisms of action. table 2: cytotoxic activity of the crude meoh extract and solvent fractions from c. sphaerocarpa resin against four human cancer cell lines using srb assay extract/fractions cell lines ic50 (g/ml) a549 a2780 mia-paca-2 snu-638 meoh 11.03 11.32 23.51 11.56 n-hexane 9.64 9.62 17.21 10.3 chcl3 11.23 11.06 24.57 10.84 etoposide, m 0.34 0.58 0.72 0.24 (inhibition of cell growth by 50%). data was generated by experiments performed in triplicates. etoposide [ m] 0.1 0.3 1.0 3.0 10.0 30.0 n e t g r o w th a s % o f c o n tr o l -50 0 50 100 a549 a2780 mia-paca-2 snu638 a03-hx [g/ml] 0.1 0.3 1.0 3.0 10.0 30.0 n e t g r o w th a s % o f c o n tr o l -50 0 50 100 a549 a2780 mia-paca-2 snu638 cspr meoh [µg/ml] cspr hx [µg/ml] csprchcl3 [µg/ml] etopoisde [µm] a) b) c) d) figure 3: cytotoxic activity of methanol extract and fractions determined by the percentage of growth inhibition. csrmeoh, csr-hx, csr-chcl3 are methanol extract, hexane chloroform, fractions, respectively, from c. sphaerocarpa resin against a549, a2780, mia-paca-2 snu 638 cancer cell lies. etoposide was used as a positive control. the values are means ± standard deviation (sd) from three replicates. worku dinku et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 27 the net growth as percent control or cell viability expressed in percentage of the crude meoh extract, nhexane and chloroform fractions showed concentrationdependence (figure 3), which decreased with an increase in crude extract and solvent fraction concentration. the a549 and a2780 cell line were the most sensitive to commiphora sphaerocarpa resin nhexane fraction with ic50 value 9.64 and 9.62 µg/ml the n-hexane fraction showed a significant dose dependent in reducing the proliferation of a549 and a2780 cancer cells at 0.1, 0.3, 1.0, 3.0, 10.0, and 30.0 µg/ml (figure 3b). particularly, the cell viability of the cancer cell line decreased sharply at higher concentration, i.e., at 10 and 30 g/ml with more than 60% and 100% inhibition. slight inhibitory activity was observed by the meoh crude extract and chloroform fraction in the range of 10.84 11.23 against a549, a2780 and snu638 cancer cell line (figures 3a and 3c). the activity presented by the crude meoh extract, n-hexane and chloroform fractions was least potent against the miapaca-2 cell line with ic50 value 23.51, 17.21 and 24.57 g/ml respectively (figures 3). 4. conclusion among the two solvent fractions tested for cytotoxicity activity, the n-hexane fraction showed better apparent cytotoxicity against a549, a2780 and snu-638 cancer cells with dose-dependent relationship in vitro compared to the chloroform fraction. chemical constituents of the most active n-hexane fraction was analyzed by gc-ms and the result revealed that pentacyclic triterpenes and sesquiterpenes were found to be major components of the fraction which might be responsible for the observed anti-proliferative effects. the findings of this study suggest that the components of n-hexane fraction of c. sphaerocarpa might be useful to treat aforementioned selected cancers after further in vivo and clinical studies. conflict of interest the authors declare no conflicts of interests. acknowledgment financial support for this work was provided by adama science and technology university and national research foundation of korea (no. 2016k1a3a1a09939937 in support of staff development program. reference al-maskri a.y., hanif m.a., al-maskari m.y., abraham a.s., al-sabahi j.n., al-mantheri o. 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(2012). the pentacyclic triterpenes α,β-amyrins: a review of sources and biological activities. in phytochemicals-a global perspective of their role in nutrition and health; intech. vollesen, k., hedberg, i., and edwards, s. (1989). flora of ethiopia. addis ababa, ethiopia. national herbarium, 3: 442-478. wang, c., yoon, s.h., jang, h.j., chung, y.r., kim, j.y., choi, e.s., and kim, s.w. (2011). metabolic engineering of escherichia coli for α-farnesene production. metabolic engineering, 13(6):648-55. wu ,y.x., chen, y.j., liu, c.m., gao, k. (2012). four new sesquiterpenoids from ligularia cymbulifera. journal of asian natural products research, 14(12):1130-1136. xu, j., guo, y., li, y., zhao, p., liu, c., ma, y., gao, j., hou, w. and zhang, t.,(2011). sesquiterpenoids from the resinous exudates of commiphora myrrha and their neuroprotective effects. planta medica, 77(18): 2023-2028. 1 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper chemical constituents of the roots extract of dryopteris schimperiana and evaluation for antibacterial and radical scavenging activities bayan abdi, emebet getaneh, temesgen assefa, aman dekebo, hailemichael tesso, teshome abdo, yadessa melaku  department of applied chemistry, school of applied natural science, adama science and technology university, p.o.box 1888, adama, ethiopia article info abstract keywords: dryopteris schimperiana, nmr antibacterial activity antioxidant. dryopteris schimperiana (dryopteridaceae) is traditionally used in folk medicine of ethiopia against bacteria and internal parasites. in view of its traditional use and absence of scientific reports, an attempt was made to explore the chemical constituents, antibacterial and radical scavenging activities of the solvent extracts of the root of dryopteris schimperiana. in this regard, the root was successively extracted with n-hexane, chcl3 and methanol to afford 5 g (2%), 2 g (0.8%) and 26.6 g (10.6%), respectively. the n-hexane and chcl3 extracts showing similar tlc profile were mixed and fractionated over silica gel column chromatography which led to the isolation of two compounds identified as heptacosanol (1) and isorhmentin (2). the structures of the isolated compounds were accomplished using spectroscopic methods including uv-vis, ir and nmr. to the best of our knowledge, these compounds have not been reported from the genus dryopteries. the extracts and isolated compounds were evaluated for their antibacterial activities using agar well diffusion method against two gram-positive bacteria (staphylococcus aureus and bacillus subtitis) and two gramnegative bacteria (e. coli and salmonella). the results showed that the n-hexane extract, methanol extracts and isolated compounds were active against all tested bacteria, with compound 2 shown to have an inhibition zone of 17 mm which is comparable with the positive control. furthermore the extracts and isolated compounds were assessed for their radical scavenging activity using dpph assay. isorhmentin (2) displayed pronounceable % radical scavenging activity (82.8%) compared with ascorbic acid indicating its strong ability to act as radical scavenger. this study demonstrated that the antibacterial and radical scavenging activity of the root of d. shimperiana is accounted to the presence of isorhamnetin. therefore, the biological activity displayed by the constituents of the roots of d. shimperiana corroborates the traditional use of this plant against bacteria. 1. introduction plants have been known from prehistoric times to treat a wide array of diseases affecting human beings and livestocks. out of a quarter of a million identified plants in the world about one fourth has at one time or other used by some people or cultures for medicinal purpose. the use of traditional medicine for treating  corresponding author, e-mail: yadessamelaku2010@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.153 human diseases remains widespread in developing countries. the recent reports of world health organization (who) indicated that 70 to 90% of world population especially from developing countries uses plant remedies for their health care. the principal components responsible for the traditional use of these http://www.ejssd.astu.edu/ mailto:yadessamelaku2010@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.xxxx.xx bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 2 plants are accounted to the presence of secondary metabolites including flavonoids, alkaloids, terpenoids, anthraquinone, lignans, etc (chanda et al., 2006). therefore, plants are useful to humans as a source of bioactive pharmaceuticals. although many have been treated by conventional pharmaceutical approaches, there is a growing interest in the use of natural products by the general public. at the present, many scientists are interested to evaluate the chemical constituents of plants used traditionally by peoples for medicinal purpose. some plant species belonging to the genus dryopteries are among medicinal plants that are traditionally used for the treatment of wide array of diseases. pharmacologically, some species in the genus dryopteris were reported as an effective antibacterial agent against various bacterial pathogens including staphylococcus aureus, bacillus subtitis, e. coli, salmonella typhus and pseudomonas aeruginosa. some species in this genus were shown to have various biological activities including anthelmintic, antiviral, antitumor, antimicrobial, antioxidative and antiinflammatory (han et al., 2015). previous phytochemical investigation of some species in dryopteries has resulted in the isolation of flavonoids, anthraquinones (kwanzoquinone a, hydroxychryphanol, kwanzoquinone (b6, c7, d8, e9, f10)) and alkaloids (harborne, 1966; min et al., 2010; imperato, 2006; imperato, 2007). dryopteris schimperiana is traditionally used in the folk medicine of ethiopia against bacterial infections in addition to its use to remove internal parasitic worms. despite the extensive popular use of this plant as a remedy against bacteria, there is no information describing the chemical constituents, antibacterial and radical scavenging activities of the roots of d. schimperiana. therefore in this paper, we report for the first time the chemical studies, antibacterial and radical scavenging activities of the root extracts of d. schimperiana. 2. material and methods 2.1. plant material collection and authentication the roots of d. schimperiana were collected from kaka mountain lemu bilbilo district, arsi zone, oromia region, ethiopia. the plant material was identified by a botanist and deposited at the national herbarium of addis ababa university with voucher specimen gm005. the sample was washed with tap water and dried under shade at the laboratory of department of chemistry, adama science and technology university. 2.2. instruments melting point was determined in capillary tube with a thiele tube melting point apparatus. analytical tlc was run on a 0.25 mm thick layer of silica gel gf254 (merck) on aluminum plate. spots were detected by observation under uv light (254 nm) followed by dipping in vanillin/h2so4. column chromatography was performed using silica gel (230-400 mesh) merck. solvent was freed using rotavapor. infrared (ir) spectra were obtained on perkin-elmer 65ft ((ir νmax kbr 4000-400 cm-1) infrared spectrometer using kbr pellets. 1d nmr were obtained on brucker avance instrument nmr machine (bruker avance 400 nmr spectrometer) at the chemistry department of addis ababa university. 2.3. extraction and isolation the ground root of d. schimperiana (250 g) was successively extracted on maceration with each 1.5 l of n-hexane, chcl3 and meoh for 72 hrs. the extracts were filtered and concentrated using rotary evaporator to give their corresponding extracts. the profile of each extract was subsequently analyzed by tlc. the hexane and chcl3 extracts which displayed similar tlc profile were mixed. the combined extract (7 g) was dissolved and fractionated over silica gel (150 g) column chromatography using n-hexane:etoac:meoh of increasing polarities as eluent to afford 92 fractions (table 1), each 50 ml. samples showing similar spots on their tlc profiles were mixed. fractions 14-18 which showed one spot on tlc were combined and dried to afford compound 1. on the other hand, fraction 25 after rechromatographed over silica gel column chromatography afforded compound 2. 2.4. phytochemical screening tests qualitative phytochemical screening of the n-hexane and methanol extracts of the root of d. shimpiriana were done following standard procedures to detect the presence or absence of secondary metabolites including flavonoids, saponins, phenolics, terpenoids, steroids, coumarins, anthraquinones, alkaloids, phenolics and bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 3 tannins (balick, 1996). the detailed experimental procedure used to analyze each phytochemicals is presented as follows: flavonoids (alkaline reagent test): each 0.25 g crude extracts of n-hexane and methanol were treated with ethyl acetate (10 ml) and heated for 3 min using steam bath. the mixture were filtered, and mixed with ammonia (1 ml) solution. formation of intense yellow color ratifies the presence of flavonoids (balick, 1996). table 1: column chromatographic fractionation of the combined hexane and chloroform extracts of the root of d. shimpiriana eluent ratio fractions n-hexane 100% f1-f4 n-hexane/etoac 98:2 f5f7 “ 96:4 f8-f10 “ 90:10 f11-f13 “ 80:20 f14-f18 “ 75:25 f19-f26 “ 70:30 f27-f31 “ 60:40 f32-f33 “ 50:50 f34-f37 saponins (froth test): each 0.25 g crude extracts of nhexane and methanol were dissolved and diluted with distilled water (10 ml) and shaken for 15 min. formation of layer of foam indicates the presence of saponnins (balick, 1996). phenolics (ferric chloride test): each 0.1 g crude extracts of n-hexane and methanol were treated with few drops of 2% of fecl3 and the formation of bluish green to black color indicates the presence of phenols (balick, 1996). test for tannins (gelatin test): to the crude extracts 1% gelatin solution containing sodium chloride was added. formation of white precipitate indicates the presence of tannins (balick, 1996). terpenoids (salkowski test): the extracts (5 mg) were mixed with 2 ml of chloroform and filtered. the filtrates were treated with few drops of concentrated h2so4, shaken and allowed to stand. appearance of golden yellow color indicates the presence of terpenoids (balick, 1996). steroids (salkowski test): one ml of the extracts (1 mg/ml) was dissolved in 10 ml of chloroform and equal volume of concentrated h2so4 was added by sides of the test tube. the upper layer turns red and h2so4 layer showed yellow with green fluorescence. this indicates the presence of steroids (balick, 1996). coumarins: to 2 ml (1 mg/ml) of the extract was added 3 ml of 10% naoh. formation of yellow color indicates the presence of coumarins (balick, 1996). anthraquinones: the extracts (1 mg/ml) were boiled with 10% hcl for few min. in water bath and filtered. the filtrate was allowed to cool and equal volume of chcl3 was added to the filtrate. few drops of 10% ammonia were added to the mixture and heated. the formation of rose-pink color was taken as an indication for the presence of anthraquinones (balick, 1996). alkaloids (wagner’s test): the extracts (1 mg/ml) were dissolved individually in dilute hcl and filtered. filtrates were treated with wagner’s reagent (iodine in potassium iodide). formation of brown/reddish precipitate indicates the presence of alkaloids (balick, 1996). 2.5. antibacterial activity the methanol extract, n-hexane extract and the two isolated compounds were evaluated for their in vitro antibacterial activity using disc diffusion method against two gram positive bacterial pathogens (staphylococcus aureus and bacillus subtilis) and two gram negative bacteria (escherichia coli, and salmonella thyphimurium). the bacterial cultures were inoculated into the muller hinton agar (mha). approximately, 20 ml of sterile mha were poured into sterile culture plates and allowed to set wells of about 6 mm in diameter which were punched on the plates. the tests were conducted at 5 mg/ml for both crude extracts and isolated compounds. bacterial concentration was prepared at 1.3×108 cfu/ml. the plates were incubated at 37°c. the antibacterial activity of the plant extracts and compounds were evaluated by measuring the zone of inhibition against the test organism after 24 hr (tiwari, 2011). the results were calculated as averages of triplicate tests. the zone of inhibitions in all cases were includes the diameter of the wells. dmso was used as negative control during the whole test on bacteria while amoxil was used as positive control. bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 4 2.6. dpph radical scavenging assay the radical scavenging assay of the extract and constituents of the roots of dryopteris shimpiriana were assessed using dpph according to the following procedure (rivero-perez et al., 20017). in view of this, the hexane extract was dissolved in methanol to afford 1 mg/ml. it was serially diluted in methanol to give concentration of 500, 250, 125 and 62.5 µg/ml. to 1 ml of each concentration, 4 ml dpph (0.04%dpph in meoh) was added to make 100, 50, 25 and 12.5 µg/ml solutions. this was repeated for the methanol extracts and isolated compounds. then all the samples prepared were incubated in an oven at 37oc for 30 min. and then absorbance was recorded at 517 nm using uv-vis spectrophotometer. the experiments were done triplicates and results were reported as averages of the triplicates. the percentage inhibition was calculated using the formula (boakye-yiadom, 1997). (%) inhibition = (a control a sample) a control ×100 where a control was the absorbance of the dpph solution and a sample was the absorbance in the presence of sample in dpph solution. samples were analyzed in triplicate. ascorbic acid was used as positive control. 3. results and discussion the roots were successively extracted with nhexane, chcl3 and meoh to afford 5 g (2%), 2 g (0.8%) and 26.7 g (10.6%) crude extracts, respectively. the latter extract was found to be red in color while the first two were black. as clearly observed, the extract yield obtained using meoh was higher compared to n-hexane and chcl3. this indicates that the secondary metabolites present in the roots of d. shimpiriana are mainly polar. 3.1. phytochemical screening the combined n-hexane and chloroform extracts, and methanol extracts of the root of dryopteris shimpiriana was screened for its secondary metabolites including alkaloids, saponins, terpenoids, phenolics, tannins, anthraquinones, flavonoids, steroids and coumarins with the results depicted in table 2. as revealed from table 2, the n-hexane/chcl3 and methanol extract of the root of dryopteris shimpiriana contains secondary metabolites including alkaloids, terpenoids, anthraquinones, and flavonoids. however, neither steroids nor tannins were detected in the nhexane/chcl3 and methanol extracts. flavonoids are classes of natural products that are used as an essential component in a variety of nutraceutical, pharmaceutical, medicinal and cosmetic applications. this is attributed to their anti-oxidative, anti-inflammatory, antimutagenic and anti-carcinogenic properties coupled with their capacity to modulate key cellular enzyme function (aoki et al., 2000). therefore, the presence of flavonoids in this plant is significant as the plant may serves as anti-oxidative, anti-inflammatory, antimutagenic and anti-carcinogenic properties. hitherto, secondary metabolites including saponins, flavonoids, alkaloids, anthraquinones, and terpenoids exert antimicrobial activity through different mechanism (ghamba et al., 2014). therefore, the presence of one or more of these secondary metabolites may account for the traditional use of this plant against bacteria. . table 2: phytochemical screening results of the roots extracts of dryopteris shimpiriana secondary metabolites test/reagents hexane and chcl3 extract methanol extract alkaloids wanger test + + saponins froth test + + terpenoids salkowskis test + + phenolics ferric chloride test + + tannins gelatin test anthraquinones 10%hcl & then nh3 + + coumarins 10%naoh + + flavonoids alkaline test + + steroids salkowskis test (+) indicates presence (-) indicates absence bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 5 3.2. characterization of isolated compounds two compounds were isolated from the combined nhexane and chloroform extracts of the root of dryopteris shimpiriana. the detailed structure elucidations of these compounds are presented below. compound 1 (12 mg) was isolated as white solid melting at 82-83oc (lit. 81-82oc) (koay, c.y., et al., 2013). the uv-vis spectrum (chcl3) showed absorption maxima neither in the ultra-violet nor in the visible region indicating the absence of conjugated chromophore. the ir spectrum displayed absorption bands at 3400 and 2950 cm-1 due to hydroxy and aliphatic c-h stretching, respectively. the 1h-nmr spectrum (cdcl3) demonstrated a triplet signal at δ 3.66 (2h, j = 6.8 hz) assigned to methylene protons on oxygenated carbon. the spectrum also displayed another signal at δh 1.61 (4h, m) which were assigned to four protons on two methylene carbons next to carbon bearing oxygen. the presence of many methylene protons integrating for 46 hydrogens is evident at δh 1.27 (46h, brs). this clearly indicates the presence of overlapping signals due to many methylenes in the structure of the compound. the upfield signal at δh 0.89 (3h, t, j = 6.8 hz) is diagnostic for the presence of terminal methyl group. the 13c-nmr spectrum with the aid of dept-135 showed the presence of ten well resolved carbon signals of which nine are due to methylenes and one is methyl group. the downfield signal observed at δc 63.1 is ascribed to an oxygenated methylene carbon. this agreed very well with the data obtained from the proton nmr spectrum. the spectrum also displayed signals due to methylene carbons in the aliphatic regions at δc 32.8, 31.9, 29.7, 29.6, 29.4, 29.3, 25.7 and 22.7. the intense signal observed at δc 29.7 is due to the presence of seventeen overlapping methylene carbons which agreed well with the 1h-nmr. furthermore, the carbon resonance at δ 14.1 is characteristic signal for terminal methyl group. the above nmr spectral data generated indicated that compound 1 is a long chain alcohol named as heptacosanol whose structure is shown in figure 1. oh 1 27 1 figure 1: structure of heptacosanol (1) comparison of the nmr spectral data of compound 1 with those reported in the literature for 1-heptacosal (koay et al., 2013) was in close agreement (table 3). this compound was previously reported from the leaves of strobilanthes crispus (koay et al., 2013) but has not been reported from any species of dryopteris. compound 2 (17 mg) was isolated as a yellow solid from the combined n-hexane and chcl3 extract of the root of dryopteris shimpiriana. the uv-vis spectrum (meoh) showed absorption maxima at 271 and 338 nm suggesting the presence of a flavonoid chromophore. the ir spectrum displayed an absorption band at 1646 cm-1 attributable to an α, β-unsaturated carbonyl. the presence of c-o and c-h stretching were evident from the observed absorption bands at 1090 and 2924 cm-1, respectively. table 3: 1hand 13c-nmr spectral data of compound 1 with those reported in the literature for heptacosanol, δ in ppm and j in hz nmr spectral data of compound 1 data reported for 1-heptacosanol (koay et al., 2013) 1h-nmr 13c-nmr 1h-nmr 13c-nmr 3.66 (2h, t, j = 6.60, h-1) 63.1 (c-1) 3.64 (2h, t, j = 6.30, h-1) 63.1 (c-1) 1.61 (4h, m, h-2&3) 32.8 (c-2) 1.57 (4h, m, h-2&3) 32.8 (c-2) 1.27(46h, br s, h-4 to h-26) 31.9 (c-3) 1.25(48h, br s, h-3 to h-26) 31.9 (c-3) 29.7-29.3(c4-24) 29.7-29.3(c4-24) 25.7 (c-25) 25.7 (c-25) 22.6 (c-26) 22.6 (c-26) 0.89 (3h, t, j = 6.8, h-27) 14.1 (c-27) 0.88 (3h, t, j = 6.60, h-27) 14.1(c-27) bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 6 the 1h-nmr spectrum showed signals in the aromatic region at δh 6.45 (1h, br s) and 6.61 (1h, br s) which are apparently assigned to protons on a ring of flavonoid skeleton. the proton signals at δh 7.13 (1h, d, j = 8.4 hz), 7.76 (1h, unresolved dd, j = 8.4 hz) and 7.85 (1h, bro s) indicates abx muntiplicity pattern suggesting a trisubsitituted b-ring of the flavonoid skeleton. the signal due to the presence of one methoxy protons is evident at δh 3.98 (3h, s). the proton decoupled 13c-nmr spectrum with the aid of dept-135 displayed the presence of five methine, one methyl and ten quaternary carbons (table 4). the presence of α, β-unsaturated ketone is evident from the appearance of the carbonyl carbon signal at δc 178.2 (c4). the spectrum showed the presence of seven quaternary carbon signals in the oxygenated aromatic/olefinic regions at δc 163.7 (c-7), 161.0 (c-5), 156.5 (c-2), 156.2 (c-9), 144.8 (c-4̍), 144.4 (c-3̍), 120.9 (c-1̍) and 137.9 (c-3). two typical sp2 quaternary carbon signals were observed at δc 137.9 and 104.4 attributed to c-3 and c-5a carbons of flavonoid skeleton. the presence of five methine signals are evident at δc 121.3 (c-6̍), 114.9 (c-2̍), 114.8 (c-5̍), 98.4 (c-6) and 93.5 (c-8). the latter two signals are characteristics of c-6 and c8 of the ring a of flavonoid skeleton, respectively, suggesting meta oxygenation substitution pattern of ring a. the up field signal at δc 59.4 is typical for the presence of only one methoxyl in the structure of the compound. the above spectral data and comparison with literature suggests that the compound is identical with isorhamnetin (2, figure 2, table 2) (josé et al., 2012). o oh o o oh oh ho 46 8 2 1' 6' 4' 2 figure 2: structure of isorhamnetin (2) the 13c-nmr spectral data of compound 2 was also compared with the literature reported for isorhamnetin with the data presented in table 4. 3.3. antibacterial activity the antibacterial activity of the hexane extract, methanol extract and the two isolated compounds from the roots of dryopteris shimpiriana were investigated using agar well diffusion method, against some selected human pathogens such as e. coli, bacillus subtilis, s. aureus and salmonella typhimurium (table 5). the antibacterial activity of extracts and isolated compounds against bacterial pathogens using agar well diffusion method is expressed using inhibition zones. antibacterial activity (x) is then characterized and classified based on the inhibition growth zone diameters and described as slight (x< 4 mm diameter), medium (x = 4-8 mm), high (x = 8-12 mm), and very high (x> 12 mm) (obdak et al., 2017). in view of this, the extracts and isolated compounds assessed in the present study showed considerable antibacterial activity against three bacterial starins i.e s. aureus, e. coli and s. thyphlomurium compared with the positive and negative controls. the activities displayed by both table 4: nmr spectral comparison of isorhamnetin isolated from dryopteris shimpiriana and one that reported in literature (josé et al., 2012) s no 13c-nmr data of 2 literature reported for isorhamnetin s no 13c-nmr data of 2 literature reported for isorhamnetin 2 156.5 156.7 5a 104.4 105.5 3 137.9 135.2 1̍̍ ̍ ˈ 120.9 120.9 4 178.2 177.5 2ˈ 114.9 114.6 5 161.0 160.8 3ˈ 144.4 146.3 6 98.4 99.2 4ˈ 144.8 149.5 7 163.7 162.7 5ˈ 114.8 113.5 8 93.5 94.4 6ˈ 121.3 122.1 8a 156.2 155.9 och3 59.4 59.3 bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 7 table 5: zone of bacterial growth inhibition diameter (mm) sample (5 mg/ml) zone of inhibition diameter (mm) s. aureus b. subtitus e. coli s. thyphlomurium hexane extract 13.0 ± 0.42 9.0 ± 0.3 10.3 ± 0.42 9.0 ± 0.51 methanol extract 10.0 ± 0.5 9.0 ± 0.38 10.0 ± 0.51 9.6 ± 0.2 compound 1 12.0 ± 0.4 nt 13.6 ± 0.2 nt compound 2 17.0 ± 0.2 9.6 ± 0.13 12.6 ± 0.3 10.6 ± 0.24 amoxil 23.0 ± 0.4 20.0 ± 0.5 20.0 ± 0.34 18.0 ± 0.2 dmso results are reported as m± sd; nt: not tested; amoxil and dmso were used as positive and negative controls, respectively compounds are relatively better than the extracts. compound 1 and 2 showed promising antibacterial activity against e. coli and s. aureus with zone of inhibition of 13.6 ± 0.2 and 17.0 ± 0.2, respectively, compared to amoxil (20.0 ± 0.34 and 23.0 ± 0.4, respectively) suggesting the activity displayed by the extracts of the root of d. shimpiriana is likely accounted to the known flavonoid, isorhamnetin. the activity displayed by the two extracts is likely accounted to the presence of various secondary metabolites including saponins, flavonoids, alkaloids, anthraquinones, and terpenoids. this agrees very well with the previous report which indicated as these secondary metabolites exert antimicrobial activity via different mechanism (ghamba, et al., 2014). analysis of the antibacterial activity revealed as compound 1 and 2 were both active against all tested bacteria. the activities displayed by both compounds are relatively better than the extracts. especially noteworthy is the very high activity of compound 2 (17 mm) shown against s. aureus. the result is superior compared with compound 1 and the two extracts, and comparable with the positive control. furthermore the antibacterial activity displayed by the extracts and isolated constituents of the root of d. shimpiriana substantiates the traditional use of this plant against bacteria. 3.4. radical scavenging activity dpph radical scavenging assay is a simple method for finding antioxidants by measuring absorbance at 517 nm due to the stable 2, 2-diphenyl-1-picrylhydrazyl (dpph) radical. those compounds that exhibit antioxidant activity change the purpled colored dpph reagent to yellow in addition to their ability of lowering the absorbance at 517 nm. this phenomenon results due to the quenching of the dpph radical and formation of dpph-h that would lower absorption. in this work, the extracts and isolated compounds from the roots d. shimpiriana were evaluated using dpph assay (table 6). table 6: results of radical scavenger activity of extracts and isolated compounds samples %dpph inhibition at 100(µg/ml) 50 (µg/ml) 25 (µg/ml) 12.5 (µg/ml) hexane/chcl3 extract 60.3±0.05 54.1±0.01 47.5±0.08 41.2±0.02 meoh extract 63.9±0.01 51.6±0.01 44.7±0.07 36.5±0.10 compound 1 44.7±0.03 40.0±0.05 33.3±0.01 25.7±0.02 compound 2 82.8±0.01 77.1±0.01 71.4±0.02 63.8±0.03 ascorbic acid 90.0±0.02 bayan abdi et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 8 the % dpph inhibition shown by the methanol extract and the combined n-hexane/chcl3 extract is 63.9 and 60.3%, respectively. the activity displayed by the extract is accounted to the presence of flavonoids which was confirmed by the alkaline test. on the other hand, compound 2 displayed pronounceable free radical scavenging activity with an average percent inhibition of 82.8, 77.1, 71.4, and 63.8% at 100, 50, 25 and 12.5 μg ml-1, respectively. the result is significant compared to ascorbic acid which inhibited the radical by 90% at 100 μg ml-1. further confirmation of the antioxidant activity of compound 2 was made due to the observed immediate discoloration of the purple dpph solution to yellow. therefore, the radical scavenging activity of the roots of d. schimperiana is accounted to the presence of the known flavonoids, namely, isorhamnetin (2). 4. conclusions in conclusion, phytochemical screening analysis conducted on roots extract of dryopteris schimperiana revealed the presence of alkaloids, terpenes, anthraquinone, flavanoids, and tannins. the combined n-hexane and chcl3 extract after silica gel column 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(2017). comparison of antibacterial activity of lactobacillus plantarumstrains isolated from two different kinds of regional cheeses from poland: oscypek and korycinski cheese, biomed research international, 9:1-10. rivero-perez, m.d., muniz, p., sanjase, m.l. (2007). antioxidant profile of red coines evaluated by total antioxidant capacity, scavenger activity, and biomarkers of oxidative stress methodologies. journal of agricultural and food chemistry, 55(14): 5476-5483. tiwari, p., kumar, b., kaur, m., kaur, g., kaur, h. (2011). phytochemical screening and extraction: a review. internationale pharmaceutica sci-encia, 1: 98-106 https://www.ncbi.nlm.nih.gov/pubmed/?term=napolitano%20jg%5bauthor%5d&cauthor=true&cauthor_uid=22730238 https://www.ncbi.nlm.nih.gov/pubmed/?term=lankin%20dc%5bauthor%5d&cauthor=true&cauthor_uid=22730238 https://www.ncbi.nlm.nih.gov/pubmed/?term=chen%20sn%5bauthor%5d&cauthor=true&cauthor_uid=22730238 https://www.ncbi.nlm.nih.gov/pubmed/?term=pauli%20gf%5bauthor%5d&cauthor=true&cauthor_uid=22730238 https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=22730238 51 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 the status of career guidance in ensuring quality education in harar and woliso technical and vocational colleges, ethiopia kumsa donis likisa adama science and technology university, school of humanities and social science, p. o. box 1888, adama, ethiopia, e-mail: kumsalikisa2009@gmail.com . abstract the main objective of this study is to examine the contribution of career guidance in quality education in harar and woliso technical and vocational colleges. descriptive survey research design was employed to assess the status of career guidance in ensuring quality education in the two selected colleges. the sources of information were two purposefully selected guidance personnel, 190 students and 93 instructors who were randomly selected after stratification based on their fields of studies. questionnaires were used as data gathering instruments. in the analysis of data, qualitative description of information from the open-ended questions and statistics such as frequency and percentage were used in the analysis of closed-ended questions. the results of the empirical investigation indicated a lack of policy guideline at the institutional level, which is considered to be indispensable to the initiation and to sustain career guidance. systematic career guidance and guidance programmes are lacking, and there is a scarcity of facilities that should have been set aside for career guidance. the personnel providing career guidance are not appropriately trained, and seldom received the opportunity to undergo in-service training. as a result, career guidance is not contributing to quality education as required. finally, recommendations and suggestions for further investigation were made. keywords: career guidance, career development, quality education, tvet colleges 1. introduction career guidance is useful in selfawareness, opportunity awareness, decision-making skills and transition skills (watts et al, 1996; lussier, 2005; koul, 2006), thus, assists individuals to make satisfying educational, training and occupational choices and to manage their careers (sultana, 2004). career guidance also increases effectiveness of training, industrial efficiency and promote the adjustment of the workers (guilford, 2005), and ensure lifelong learning, social inclusion, labour market efficiency, and economic development (scheerens, 2004). a variety of career theories offer the conceptual framework for career guidance interventions in assisting students to achieve their career goals. these theories can be thematically organised under person-environment fit theories, developmental theories and cognitive-behavioural theories. according to person-environment fit theories there are unique innate traits and attributes mailto:kumsalikisa2009@gmail.com kumsa donis ejssd, v 5 (2), 2018 52 © adama science & technology university https://ejssd.astu.edu.et required for different kinds of work that can be measured and matched with one’s occupational profile (coertse & schepers, 2004). person-environment fit is making match or alignment between persons’ characteristics and environmental requirements (sekiguchi, 2004). developmental theories have the viewpoint that choosing a career and managing one's career development involve a continuous process that carries on through life (herr & cramer, 1996; coertse & schepers, 2004). thus, these theories give more weight to the view that individuals fit into various occupations at different times in their lives. the cognitive-behavioral theories advocate the multiple sources of influence in one’s career development. like person-environment theories, the cognitive-behavioral theories emphasize the importance of genetic make-up, selfawareness, occupational information and integration of self-awareness and occupational information. akin to developmental theories, the cognitivebehavioral theories underline that career development is development sensitive. unlike the two, the sources of career development are not only related to those content and process characteristics, but also equally related to past learning experiences, family, social and cultural restrictions or socialization, work-related attitudes and values. all theories have the presumption that by attending students’ career development it is possible to increase the intensity of achievement motivation and facilitate students’ ability to achieve academically (gysbers & henderson, 2006 as cited in rivera & schaefer, 2009). rivera and schaefer (2009) further identified that career development interventions can contribute to quality education by developing students’ sense of engagement in school and higher levels of motivation. it also contributes to the internal efficiency of the higher learning institutions by reducing repetition rate and dropout rate, and increase graduate output (auma-okumu, 2011). reciprocally, quality education enhances career development because it is through education that one can identify his/her potential, interest and determine in which vocation and occupation to pursue. educational experiences also promote career-related attitudes and knowledge about oneself and the realities of the world of work. thus, career guidance bridges between education and career development. however, worldwide there is lack of trained personnel in higher learning institutions providing career guidance (international organisation for economic co-operation and development, 2004; european centre for the development of vocational training, 2009) and the existing guidance concentrate on personal or study/academic guidance rather than ensuring students’ career development (lairio & penttinen, 2006; niles & harris-bowlsbey, 2009; sharf, 2006), plan career guidance and assign skilled counsellors (heppner & johnston,1989; stead & watson, 1998) that in turn contribute to quality of kumsa donis ejssd, v 5 (2), 2018 53 © adama science & technology university https://ejssd.astu.edu.et education (chireshe, 2006; debono et al., 2007). similarly, in spite of the fact that the 1994 ethiopian education and training policy (ministry of education, 1994) strive to warrant the interface among career guidance, career development and education, the existing career guidance in ethiopia is not responsive to students’ career development and ensuring quality of education. the integration of career development and quality education in educational system is usually overlooked and scarce attention was given by researchers (yilfashewa, 2011; yirgalem, 2013). thus, whether institutional guidance policy guideline is in place or not, resources are properly allocated and the extent to which the existing career guidance is contributing to improve the quality of education in ethiopia are unknown. the intention of this study is, therefore, to answer the following research questions: 1. how well are career guidance policy guideline and resources organized in harar and woliso technical and vocational colleges? 2. what are the perceptions of guidance personnel and students as to the effectiveness of career guidance in their colleges? 3. how well is career guidance service organised in a way to ensure quality of education in harar and woliso technical and vocational colleges? 2. research design and methodology 2.1 research design the goal of this empirical research is to investigate the status of career guidance and its contribution to quality education in woliso and harar tvet colleges. this study made use of descriptive survey research design with quantitative research method. a descriptive survey research design was used to describe the current status of career guidance and its contribution to quality education. a survey study was used as a quantitative research design. it mainly focuses on research design, test and measurement procedure of a reality and statistical analysis to respond to research questions requiring numerical data (williams, 2007). the quantitative research method is used to obtain numerical data (ary, jacobs & sorenson, 2006). 2.2 population and sample in the selection of 93 (40%) instructors and 190 (10%) third year students a random sampling technique was used after stratification according to their fields of studies in the two selected tvet colleges. the selection of respondents from each field was to obtain information regarding the situation of career guidance and its contribution to quality education in each field. guidance personnel (one from each college) were purposefully included in the study. the selection of the two colleges depends on the kumsa donis ejssd, v 5 (2), 2018 54 © adama science & technology university https://ejssd.astu.edu.et information that they provide guidance and counselling service by guidance personnel, instructors or at least by guidance committee. 2.3 instruments questionnaires were used to acquire information from the respondents. the questionnaires were used to obtain information from students and instructors concerning their observation and opinion of the status of career guidance and its role in quality education in their institutions. the questionnaire for the instructors and guidance personnel is focused on guidance programmes, guidance personnel/instructors qualifications, their training and competence as well as how career guidance and quality education are linked. the questionnaires for students gathered information about support offered to students in their career development including information on self-awareness, career knowledge, career decision-making, career planning, integration of selfknowledge and career information, job hunting skills and career maturity as it is related to quality education. prior to using the questionnaires for the main study, questionnaires were administered to 30 instructors and 60 students and item analysis was used to determine the reliabilities of items. item analysis was also used to identify and retain relevant and effective items while at the same time exclude items which might be irrelevant. cronbach’s alpha was used to determine internal reliability coefficients or whether constituent items are measuring the same domain (jack & clarke, 1998). all the constructs found to have high reliabilities as their reliabilities exceed 0.80. this indicates that the instruments provide dependable information from which reliable conclusions can be made. 2.4 data collection the questionnaires were applied at two colleges by the researcher. the questionnaire for students was completed during 50-minute class periods and the questionnaire for instructors was completed at their home or office. in order to obtain honest responses, consent letters were attached to each questionnaire and the respondents were instructed not to write their names on the questionnaires. student participants received instructions on how to complete the surveys for the first five minutes of the classes. 2.5 data analysis the statistical packages for social sciences (spss) version 17.0 was used in the analysis of data. the analysis of data was done by calculating percentages. these kumsa donis ejssd, v 5 (2), 2018 55 © adama science & technology university https://ejssd.astu.edu.et summarised responses were used to interpret the data and draw conclusions. 3. results and discussion 3.1 results 3.1.1 students’ perception of the effectiveness of career guidance programme the effectiveness of guidance program was evaluated by students in terms of the supports and information including backing students in selfawareness (personal development, aptitude and interest), career knowledge, career decision-making, career planning, integrating self-knowledge and career information and job hunting skills. their responses are summarized in table 1. it is emerged from the results that students were not supported in selfawareness (personal development, aptitude and interest), career knowledge, career decision-making, career planning, integrating selfknowledge and career information that determine educational choice and decision on career paths, job hunting skills and transition skills. these aspects of career guidance were not used to ensure students’ career development and quality of education. accordingly, 62.32% of the students in the two colleges felt that they have not received adequate support and information regarding their personal development, aptitude and interest mainly due to the absence of guidance curriculum package. regarding career knowledge, the majority of the students (61.14%) reported that they have not received adequate support and information using diverse sources of career information such as from printed, ict-based, professionals and employers. they were also not informed about advantages and disadvantages of a range of jobs, job requirements of different occupations, how to evaluate and use labor market information, the financial output of different occupations and potential for advancement in different occupations. smaller proportion (31.92%) of the respondents replied that they received support and information on career decision-making. more than half of the students (52.47%) reported that they have not received support and information regarding career decision-making. this means that students did not get support in weighing the advantages and disadvantages of different jobs and factors to be considered in career decision-making like, for example, the impact of career decisions on oneself and others, how to make decision during career transitions and how to overcome situation interfering with career decisions. kumsa donis ejssd, v 5 (2), 2018 56 © adama science & technology university https://ejssd.astu.edu.et table 1. summary of students’ perception of the effectiveness of career guidance in their career development no. construct n average dd/ds (%) ud (%) as/da (%) in your college, you have received support and information regarding: 1 self-awareness. 190 62.32 14.56 23.07 2 career knowledge. 190 61.14 13.18 25.67 3 career decision-making. 190 52.47 15.64 31.92 4 career planning. 190 55.48 16.98 27.52 5 integration of self-knowledge and career information. 190 50.12 18.20 31.68 6 job hunting skills. 190 61.14 13.18 25.67 7 career maturity. 190 62.32 15.56 22.07 average 57.76 15.35 26.91 note that dd/ ds= definitely disagree/disagree somewhat, ud=undecided and as/ da= agree somewhat/definitely agree. smaller number of students (27.52%) indicated that they have received support and information on career development and 16.98% are not sure. however, 55.48% of the students agreed that they have not obtained adequate support and information concerning career planning at their colleges. pertaining to support and information in integrating self-knowledge and career information, half of the students (50.12%) reported that they have not received adequate support and information, 18.2% of them are not sure and 31.68% felt that they received support and information in integrating selfknowledge and career information compatible with their personalities, aptitudes and interests. although the positive response (31.68%) shows the presence of promising scenario, a considerable number of respondents (18.2%) who remained undecided or showed their disagreement (50.12%) indicate the presence of gap in support and information in integrating self-knowledge and career information. regarding job hunting skills, 61.14% of the respondents indicated that at their college, there were not classes/lectures they attended that helped them on jobsearch activities such as job-search skills, job-application, preparing résumé (cvs), and preparing for selection interviews. due to lack of job hunting skills, they do not know what employers look for in relation to behaviour at work, how to do network with potential employers, how to find job online, at an employment agency or by networking, newspaper, private employers or job search support groups. they could not also develop the kumsa donis ejssd, v 5 (2), 2018 57 © adama science & technology university https://ejssd.astu.edu.et feeling that when one door closes, another opens. as to career maturity, 62.32% showed that they lack career maturity because they indicated that they do not know which kind of work to choose, the possibility to be successful in different occupations, the need to take a job that is not their first choice sometimes, the influence of other on their career choice, about requirements of jobs and the need to make informed decision. lack of career maturity indicates the absence of guidance curriculum that assist students to make informed career choice, factors to consider in career choice and how to look for different career options. in general, the majority of the students agreed that career guidance was not systematically designed and used to enhance students’ career development and there is a trend to send students without ensuring their career maturity indicative of educational quality crisis and difficulty in obtaining goal oriented behaviours with employability skills. 3.1.2 guidance personnel/instructors perception of the effectiveness of career guidance programme guidance personnel/instructors perception of the effectiveness of career guidance programme was evaluated from the perspective of the presence or absence of career guidance policy (written or unwritten), action plan, career education, stakeholders’ involvement and career model. the presence or absence of the four factors is summarized in table 2. with regard to career guidance policy guideline, about 73% of the respondents indicated that there is no career guidance policy guideline in their colleges. their colleges have no clear career guidance policy /guideline to give its students the tools and knowledge to realistically plan for their future career and budget which meant for career guidance. table 2. presence or absence of career guidance policy guideline, action plan, career education, stakeholders’ involvement and career model no. construct n present (%) absent (%) undecided (%) 1 career guidance policy guideline 95 2.86 73.10 23.94 2 action plan 95 6.67 56.67 36.67 3 career education 95 7.01 79.81 12.32 4 stakeholders’ involvement 95 1.86 73.10 24.94 5 career model 95 4.80 75.2 20.05 average 4.64 71.576 23.584 regarding action plan, about 57% of the respondents indicated absence of action plan. there is no systematically planned and organised guidance programmes focusing on academic, career and personal-social development. kumsa donis ejssd, v 5 (2), 2018 58 © adama science & technology university https://ejssd.astu.edu.et they felt that the objectives were not prioritised with time frame into immediate (1 year), short-term (5 to 10 years) and long term tasks for its accomplishment. strategies were not devised to deliver career interventions, the responsibilities of stakeholders were not identified and means to evaluate the successes and failures of guidance programmes were also not established. concerning career education, the majority (80%) of guidance personnel/ instructors agreed that there was no career education received by students in their colleges. attention was not given to students’ understanding of their interests, abilities, the requirements of various occupations through systematic reflection of workplace environment and active on job participation. similarly, from the open-ended questions it was found that there is no career guidance and career education for the students. educational and vocational choices are more of the result of pressure from unqualified individuals such as peers, parents and significant others. 3.1.3 resources and facilities the two colleges’ guidance personnel reported scarcity of equipments and materials (facilities) such as computer, printer, telephone, shelve, filing cabinet, modem and internet, photocopier, fax and scanner. there are also lack of audio and visual, psychometric tests, handbooks, bulletins and magazines which are necessary to run guidance and counselling services properly. the opening of the office is in name only. the implication is that scant attention is given to guidance and counselling services by the two colleges’ management. 3.1.4 link between career guidance and education instructors’ were asked to rate the contribution of career guidance to make the education system work thereby improve quality education. their responses are summarized in table 3. on average, 62% of the respondents designated that career guidance is not in place to enhance quality education. however, 25% of the respondents have the view that it is serving the purpose. on the other hand, 13% of the respondents are not sure whether career guidance is supporting in achieving quality of education. more specifically, guidance service at the two colleges is not used as a mechanism for making the education system work. it is not contributing to improve the efficiency of the education system by reducing attrition rate; helping students make the appropriate choices from among different departments and career pathways; promoting a closer link between education and work by enabling young people to gain the knowledge and skills required in the world of work, and communication skills, teamwork, creativity, etc. that are increasingly required by employers. kumsa donis ejssd, v 5 (2), 2018 59 © adama science & technology university https://ejssd.astu.edu.et table 3. instructors’ view about the contribution of career guidance to quality education no item n average dd/ds (%) ud (%) as/da (%) 1 guidance services in your college contributed to improve the efficiency of the education system by: (a) reducing attrition rate. 95 69% 23% 8% (b) helping students make the appropriate choices from among different departments/ career pathways. 95 53% 13% 34% (c) promoting more in-depth learning by using experiential learning approaches. 95 51% 13% 36% 2 guidance services in your college promoted a tighter link between education and work by: (a) teaching students about work, either directly through extra-curricular seminars or through a timetabled career education programme; or indirectly, by providing resources to regular instructors who address work-related issues in the subjects they teach. 95 47% 18% 35% (b) providing a structured exposure to work for learning purposes through entrepreneurship schemes, and work shadowing or work experience programmes. 95 70% 21% 9% (c) promoting ‘soft skills’ such as communication skills, teamwork, creativity that are increasingly required by employers. 95 62% 9% 29% 3 the guidance service at your college enabled young people to gain the knowledge and skills required in the world of work 95 65% 5% 30% 4 career guidance in your college enhanced quality education by: a. producing students having goal directed behaviour. 95 61% 10% 29% b. helping students to acquire knowledge and attitudes about self, work and other life options. 95 65% 12% 22% c. helping students acquire knowledge, skills and attitudes necessary to make work a meaningful, productive and satisfying part of their life. 95 77% 14% 9% d. enhancing self-understanding of students related to education and the world of work. 95 76% 9% 15% e. setting achievable goals in academic and career paths. 95 56% 9% 35% kumsa donis ejssd, v 5 (2), 2018 60 © adama science & technology university https://ejssd.astu.edu.et f. enhancing competitiveness or employability skills. 95 53% 13% 34% g. making informed decision. 95 62% 16% 22% average 62% 13% 25% it is also noted that students were not properly assisted to set achievable goals in academic and career paths and they were not taught about work either directly through extra-curricular seminars or through a timetabled career education programme; or indirectly, by providing resources to regular instructors who address work-related issues in the subjects they teach to enhance self-understanding of students related to education and the world of work, and their competitiveness or employability skills. besides lack of supportive activities in their college there is also inadequate structured exposure to work for learning purposes through entrepreneurship schemes, and work shadowing or work experience programmes outside of the colleges. 3.2 discussion 3.2.1 students’ perception of the effectiveness of career guidance, guidance programme, support and information in their institutions the study revealed that students were not sufficiently supported in selfawareness, career knowledge, career decision-making and career planning. consistent with this study, lairio and penttinen (2006) also identified that there are challenges facing career guidance in higher education. students are making little thinking about their future career and forthcoming transition from college/university to working life. there is a need to assist students in prioritising alternatives and select occupation (e.g., niles & harris-bowlsbey, 2009; sharf, 2006), plan career guidance and assign skilled counsellors (heppner & johnston, 1989; stead & watson, 1998) to avoid students’ state of confusion, indecisiveness, non-involvement in the career development process, non-orientation towards work, dependence when making career choices and non-compromise when the preferred careers are difficult to attain. 3.2.2 guidance personnel/instructors’ perception of the effectiveness of career guidance and guidance programme in their institutions concerning guidance personnel /instructors background, the study revealed that the majority of the participants were inadequately participated in pre and in-service training related to career guidance. this indicates that the majority of them are not ready to provide effective guidance service because they do not have relevant training in guidance and counselling. however, nykänen et al. (2007) in european centre for the development of vocational training (2009) underscored that instructors should be kumsa donis ejssd, v 5 (2), 2018 61 © adama science & technology university https://ejssd.astu.edu.et able to play a significant role in helping individuals with their career plans and choices that require relevant training. it also emerged from the study that small amount of time is devoted to career guidance. similarly, from studies, organisation for economic co-operation and development (2004) pointed out that career guidance is not always provided on a full-time specialist basis by people who have specialized and officially recognized qualifications. the career guidance workforce often includes many but as a teacher, psychologist, counsellor, human resource specialist, employment officer or labour-market analyst whose primary occupational identity is not as a career guidance specialist. often they provide career guidance for only part of their working time. regarding action plan, the study disclosed that there is lack of wellplanned and organized guidance programmes that prioritized tasks with time frame into immediate, short-term and long term for its accomplishment. consistent with these findings, heppner and johnston (1993) found that career counsellors could not plan, prioritize, monitor and review the programme because it is given little prominence and counselling is relegated to least skilled counsellors and too often career counselling centres do not have their vision. similarly, chireshe (2006) identified that the majority of the zimbabwean counsellors do not produce plans for the guidance and counselling services. as to career education, it emerged from this study that there was no career education that enhance relationship between education, work and society in the selected colleges. the focus was on theories rather than basic skills, decisionmaking, career planning, job-seeking, job-getting and job holding skills. consistent with finding in this study, hansen (2006) posited that the problem of career education is severe in tertiary education of low and middle-income countries. in this study, it was found that there is no relevant career model used in the selected colleges. consistent with this study, o’neil, mcwhirter and cerezo (2008) found that major difficulties facing career counselling professionals is the lack of contextualizing existing theories to local situation and variant individuals. on the contrary, international literature (e.g., kato & suzuki, 2006) showed that career guidance requires a set of theoretical frameworks having not only universal validity and applications that address the needs of different students, but also culture-specific models that could be used at a local level. 3.2.3 the contribution of career guidance to quality education in spite of the need for career guidance to ensure quality education, improve students’ academic achievement, and reduce attrition rate, the present study found that career guidance is not primed to enhance quality education. students were not assisted in educational and vocational choice by setting achievable goals in academic and career paths which are useful in having goal directed kumsa donis ejssd, v 5 (2), 2018 62 © adama science & technology university https://ejssd.astu.edu.et behavior. in addition, students were not taught about work either through extracurricular activities, structured entrepreneurship schemes; work shadowing outside of the colleges or as integrated part of courses that helps in ensuring quality education. moreover, career guidance is not in place to increase the efficiency of education by reducing attrition rate, enhancing competitiveness/employability skills and promoting soft skills such as communication skills, teamwork and creativity. consistent with this study, chireshe (2006), and debono, camiller, galea and gravina (2007) found that the existing guidance concentrate on personal or study/academic guidance rather than ensuring students’ career development that in turn contribute to quality education. in general, consistent with the result of this study, from empirical study, rivera and schaefer (2009) pointed out that relatively more emphasis is given to academic, personal-social development and thus career guidance tends to be marginalised. as a result, students were not assisted in a way to understand themselves, explore the labour market which enables them to make appropriate match between themselves and the opportunities in the labour market, and career guidance is not contributing to enhance quality education in the studied two colleges. 4. conclusions from the findings of this study, it can be concluded that the provision of career guidance services in the two colleges is thin on the ground to keep in touch with the ever-changing social and economic changes, demand of students and the world of work. aspects of effective and comprehensive career guidance services are awfully inadequate. these aspects include planning, career education, facilities, competent professionals, and involvement of stakeholders, career model and eventually students’ career development. even though there are some useful points of departure, the status of career guidance services in the two colleges is far below the expected international standard. it can also be concluded that career guidance service in the two colleges is not contributing to quality education as students were not assisted in educational and vocational choice, learning by doing through extracurricular activities, structured entrepreneurship schemes and work shadowing outside of the colleges that ultimately increase the efficiency of education by reducing attrition rate, enhancing competitiveness/ employability skills and promoting soft skills such as communication skills, teamwork and creativity which are required by employers. the conclusions reached above necessitate specific recommendations; these are now made. recommendations based on the foregoing findings from the literature study, empirical investigation and conclusion the following recommendations are proposed whereby career guidance may be addressed kumsa donis ejssd, v 5 (2), 2018 63 © adama science & technology university https://ejssd.astu.edu.et effectively so as to enhance quality of education.  ethiopian ministry of education needs to start to develop public policies on career development and allocate resources to the development of career guidance services at all levels of education. specific policy guidelines also need to be established at institutional level that recognize the interaction among educational, personal-social and vocational guidance in addition to the contexts such as, cultural background, psychosocial environment and unique assets of individuals.  there is a need for systematic and quality career guidance and counselling service framed within well thought and contextualized career guidance model to ensure quality education and accessible to all students in each college.  alternative strategies need to be designed either to offer career guidance through general orientation at all levels of education, infuse career guidance across the curriculum or provide through seminars, workshops and counselling sessions in order to assist students to gain the knowledge, skills, attitudes and behaviors to manage their career more effectively and to ensure quality of education.  there is a need to replace informal, unsystematic and unscientific guidance by more formal, systematic and scientific career guidance by training counsellors and train instructors with guidance and counselling theories, career development theories and practices that is followed by continuous professional development.  finally, a national survey by ministry of education that includes colleges from different regions, including parents, alumni, top management of the colleges and industries/ organizations is recommended. acknowledgements my special thanks must go to harar and woliso technical and vocational colleges for granting me permission to undertake my field works in their colleges. i am also grateful to students, instructors and administrators in the respective colleges who participated in this study for their invaluable input and for sharing their time. references auma-okumu, ss. 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(2007). research methods. journal of business & economic research, 5(3), 65–72. yilfashewa seyoum (2011). revitalizing quality using guidance counselling in ethiopian higher education institutions: exploring students views and attitudes at haramaya university. international journal of instruction, 4 (2), 161-192. yirgalem alemu (2013). assessment of the provisions of guidance and counseling services in secondary schools of east harerge zone and hareri region, ethiopia. middle eastern & african journal of educational research, 2, 28-37. 66 83 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 study on the biogas energy potential of cactus (opuntia ficusindica (l.) mill.) jemal beshir belay1 and abubaker yimam ali2,* 1 department of sustainable energy engineering, jimma institute of technology, jimma university, jimma, ethiopia. e-mail: jtobsen@gmail.com, tel: +251912288775 2 school of chemical and bio engineering, addis ababa institute of technology, addis ababa university, addis ababa, ethiopia. e-mail: drabubeker_yimam@yahoo.com, tel: +251-11-23-24-17 *corresponding author abstract bioenergy is a renewable energy and it contribute to solve the present and future energy problems. among the alternative bio energy sources, biogas production from different sources were currently applicable. biogas production from energy crops, agriculture waste and various residential and industrial waste material are limited; thus, new renewable sources are sought after. this paper presents the experimental results of the anaerobic digestion of cactus (opuntia ficus-indica) (l.) and methane content of each of the treatments. the sample of the plant (cactus) was cut, purified from spin and homogenized. the processes of anaerobic digestion for the generation of biogas was then conducted by varying the temperature and the maturity of cactus in eight treatments as, t1 and t2 (<1-year cactus at 27°c and 37°c), t3 and t4 (1-year cactus at 27°c and 37°c), t5 and t6 (2-year cactus at 27°c and 37°c), t7 and t8 (3-year cactus at 27°c and 37°c) were performed. from 500g of cactus, it was found that the amount of biogas production and quality was highest in t2 (3500 ml of biogas and 49% ch4) and t7 produced the minimum biogas production and quality (2500ml of biogas and 33% ch4). thus, cactus can be digested alone or it can be one of the feed stock for co-digestion process. keywords: aanaerobic digestion, methane, biogas, cactus 1. introduction a large-scale biofuel feed stock cultivation using agricultural land decreased food availability and boosted food price dynamics, especially in developing countries (valentine et al., 2012). due to these negative impacts, second generation feed stocks were the alternatives for biofuel production, and research for these new feed stocks is intense. several issues must be analyzed in the search for the most appropriate substrate, including availability of agroindustrial residues, adaptation of secondgeneration energy crops to local soil and climate, transportation costs and environmental impacts (calabrò et al., 2016; chandra et al., 2012; moraes et al., 2014). among the alternative feed stock cactus (opuntia ficus-indica) is a mailto:jtobsen@gmail.com mailto:drabubeker_yimam@yahoo.com jemal beshir & abubake yimam ejssd, v 5 (2), 2018 84 © adama science & technology university https://ejssd.astu.edu.et promising feed stock for biogas production. this paper focuses mainly on biogas production from cactus (opuntia ficusindica). the advantage of the digestion of these biomass is: it does not compete with the land usage for feed or food production, which can tolerate surprising bouts of cold weather and it can be grown on veritable desert-like wastelands, where conventional crops would wither and die. although the cactus is native to semi-arid regions with stifling hot temperatures, it can also survive and even thrive in mountainous areas that can have temperatures as low as minus 15 degrees celsius. (wayland, 2010). the world has millions of hectares of land prone to drought and desertification, opuntia helps create vegetative cover, which enhances soil regeneration and improves the infiltration of rainfall back in to the soil (calabrò et al., 2017). 2. material and method 2.1. description of cactus (opuntia ficus indica) the cactus (opuntia ficus indica) used in all experiments are obtain from adigrat (tigray, ethiopia). it was collect with its age group that is <1, 1, 2, and 3 years old and the age was determined by asking the cactus farmer. the collected cactus was cut manually into small pieces and homogenize used for digestion as reported in wayland (2010). per santos et al. (2016); gabriel and victor (2014); malainine et al. (2015) and yang et al. (2015), the composition of these residuals in dried form was 7-22% cellulose, 9-19% hemicellulose, 8-16% lignin, 64-71% carbohydrate (total polysaccharides) and 17-24% ash. as reported in calabrò et al. (2017), the cactus had a total of 93.4% water, 6.6% solid content and 78.2% volatile solid content. 2.2. determination of the physicochemical properties of the feed stocks 2.2.1. total solid (ts), volatile solid (vs), carbon to nitrogen ration (c/n) 10 gm of freshly collected samples of each of cactus age were weighed using digital weight measuring device and placed inside an oven maintained at 105°c for 24 hours, then the sample ignited at 650°c in furnace for 3 hours as indicated in jigar et al. (2011) in duplicate to determine the total and volatile solid content. the carbon content of the feed stock is measured by considering the volatile solids content that was expressed as a percentage and the total carbon content was obtained from volatile solids. the kjeldahl method was employed to determine the total nitrogen content of the feedstocks. 2.3. digester composition for the purpose of this study the amount of cactus in digesters was fixed to be 500 gm (taking the digesters volume in to consideration) and the wet cactus was added to 3 l of plastic bottle digesters. to prepare the cactus for anaerobic digestion first the cactus plant jemal beshir & abubake yimam ejssd, v 5 (2), 2018 85 © adama science & technology university https://ejssd.astu.edu.et cut manualy by knife and reduce the size to 2 mm (sun and cheng, 2002) by blaender. it can be used to improve the digestibility of the lignocellulosic materials (taherzadeh & karimi, 2008). per sasse (1988) & nijaguna (2002), a wet anaerobic digestion process has an optimal total solid (ts) content of 5 to 10%. when the ts values were above the optimal value, water was added to obtain the optimum concentration of 9% ts. for this study the water content were adjusted per the indicated optimal condition and to initiate or start up the digestion process 10% of inoculem was added for all treatments (mazumdar, 1982; nijaguna, 2002). 2.4. controlling conditions the digesters’ internal working temperature was maintained at 27oc for the sample <1, 1, 2 and 3 years old cactus and 37oc for the other <1, 1, 2 and 3 years old cactus samples and ph was adjusted at 6.8 once for all treatments. this is in agreement with a ph range of 6.25 to 7.5 which is conducive for methanogenic bacteria to function properly as indicated by rai (2004). the tempreture were constant througout the process time. this tempreture is controled by using the water bath (model:hws-24, voltage 220 v, 50 hz, power 1000 w). 2.5. expermental setup the experimental set up for the study on batch digestion consists of plastic bottle with a plastic stopper (figure 1). all the eight anaerobic digesters were constructed in bench-scale experiments at which the degradation of the substrate was accomplished in sealed plastic bottles with a capacity of 3 liters in addis ababa institute of technology (aait) environmental engineering laboratory. each bottle was sealed with a rubber stopper having one outlets. the outlet was attached to the branched connector one branch connect to plastic air bag and the other one is closed and it is used to measure the volume collected gas. manual agitation was take place by shacking the digester by hand in each day. there were eight (8) treatments t1 (<1-year cactus at 27oc), t2 (<1-year cactus at 37oc), t3 (1-year cactus at 27oc), t4 (1-year cactus at 37oc), t5 (2year cactus at 27oc), t6 (2-year cactus at 37oc), t7 (3-year cactus at 27oc) and t8 (3-year cactus at 37oc). figure 1. expermental setup jemal beshir & abubake yimam ejssd, v 5 (2), 2018 86 © adama science & technology university https://ejssd.astu.edu.et 3. result and discussion 3.1. characterization of feed stocks the characteristics of feed stock (% moisture content, %ts, %vs, %c, %n and % c/n between the samples (values are mean and se, n=4)) were determined. each test were conducted two times and the average values are shown in table 1. table 1. characteristics of feed stock (% moisture content, %ts, %vs, %c, %n and % c/n between the samples (values are mean and se, n=4)) the mean moisture shows that the moisture content of cactus less than one year old cactus was higher than other cactus samples, as a result increasing the degree of digestion as bacteria can easily access liquid substrate for relevant reactions to take place easily. determining ts and vs, it is important to understand that high content of volatile fatty acids (vfas) in the substrates. the maximum ts (sample 4) was measured in 3 years old cactus, where as the minimum ts were measured from < 1 year old cactus (table 1). this may show that 3 years old cactus contain more total solids compared to other samples, but the biodegradiabilty of the sample were determined by analyzing the volatile content of substrates. the total solid content of all sample before ad was between 4.7 to 13.0%. per sasse (1988) and nijaguna (2002) biogas digesters generally follow a wet anaerobic condition process with an optimal total solid (ts) content of 5 to 10%. except the last sample (ts=13%) all sampleas were allmost under optimal condition. and out of the total solid the volatile solid (vs) were 69.2 80.8% this indicated that large fraction of cactus is biodegradable and thus it can serve as an important feedstock for biogas production. the carbon to nitrogen ratio of the feed stocks is another factor that affects the anaerobic digestion process. the percent degradation of organic carbon for < 1 year old cactus (44.9) was higher than all (from 38.4 to 41.37) (table 1). the results also revealed that there are differences in percentage of organic carbon between samples. comparison of %c showed that %c significantly decreased when the age of cactus increases. the c/n of all samples does not agree with the sugessted value 20:1 to 30:1 as reported by dahlman and forst parametres s1 (%) s2 (%) s3(%) s4(%) mean se moisture content 95.3 93 90.5 87 91.45 1.78 ts 4.7 7.0 9.5 13 8.55 1.78 vs as percentage of ts 80.8 74.3 73.7 69.2 74.5 2.39 ash as percentage of ts 19.1 25.7 26.3 30.8 25.47 2.41 c 44.9 41.3 40.9 38.4 41.37 1.34 n 1.3 0.92 0.83 0.72 0.94 0.12 c/n 34.5 44.9 49.3 53.3 45.5 4.0 jemal beshir & abubake yimam ejssd, v 5 (2), 2018 87 © adama science & technology university https://ejssd.astu.edu.et 0 100 200 300 400 500 600 700 800 900 1000 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 a m o u n t o f b io g a s (m l) retention time(days) t1 t2 t3 t4 t5 t6 t7 t8 (2001) as cited in yitayal addis (2011). this indicates that cactus needs additional substrate to minimize its c/n ratio to the optimum level. 3.2. characteristics of digesters (tempreture and ph) temperature and ph are the main factors that affect bio-digestion. consequently, the temperature were adjusted at 27oc for the treatments t1, t3, t5,t7 and 37oc for the treatments t2, t4, t6, t8. from the expermental result treatments those treated in 37oc (t2 (49% ch4), t4 (45% ch4), t6(40% ch4) and t8 (40% ch4)) produced higher amount methane when compered to other corrosponding treatments t1, t3,t5 and t7 those treated in 27oc. producing biogas in a tempreture of 37oc was much better than producing in 27oc. the ph of each digester were also adjusted 6.8 at the beginning of the digestion process. the ph of all the treatments came down at the end of the digestion period. this may be due to the formation of acids by acidogenic bacteria, the ph of the treatments were adjusted once before starting the digestion at 6.8 (ria, 2004) and after digestion the ph of the treatment were t1=5.1, t2=5.5, t3=4.7, t4=5.4, t5=4.2, t6=4.6, t7=4.5, t8=4.8. the relative higest value of the out put ph was the indication of the digestion of volatile acid and nitrogen compounds, and more methane was produced. 3.3. amount and quality of biogas production biogas production and its methane content were measured for about 45 days of digestion period until gas production was stopped. it was found that treatment t4 produced the highest (900 ml) of gas in the first 20 days of digestion, the methane% is zero for all treatments for the first 15 days, but the other gases were produced in the first five days those are co2, o2, h2s (<10ppm) and the balance were atmospheric nitrogen. this indicates that feed stock (cactus) were not satble for biogas production until day 20. figure 2. biogas production comparisim between treatments jemal beshir & abubake yimam ejssd, v 5 (2), 2018 88 © adama science & technology university https://ejssd.astu.edu.et figure 2. shows the amount of biogas (ml) produced in the whole digestion period. 2700 ml, 3500 ml, 2600 ml, 3400 ml, 2700 ml, 2600 ml, 2500 ml and 2600 ml of the total biogas produced in t1, t2, t3, t4, t5, t6, t7, and t8, respectively in the whole fermentation period. the standard diviation were 137.84, 172.24, 136.62, 250.33, 137.84, 150.55, 132.91, 196.63 for t1, t2, t3, t4, t5, t6, t7 and t8, respectivly. from the result the highest standrd diviation scored in t4 (250.33 std. diviation) which means there were the highest volume variation between measured days in test four. the amount of biogas within six treatment (t1, t3, t5, t6 , t7 and t8) were 2500 ml to 2700 ml, these indecated that the volume of biogas of the treatments were not highely affected by the controled parameters (age and temperature), but the two treatments t2 and t4 gives the higher amounts of bio gas (3500 ml and 3400 ml) than other treatments. and also t2 (<1 year cactus at 37oc) produced the maximum of average methane percentage 49% and t4 (1 year cactus at 37oc) was 45%. the maximum methane percentage were measured at day 30 for treatmets t1 up to t4 and day 35 for the remainnig four treatments. this indicated that < 1 and 1years old cactus were stable early. the lag phase was observed at the beginning of the experiment, because the cactus need time for stablization. 3.4. comparison of treatments figure 3. indicate that the total gas production and the percentage of methane of treatments (t2 and t4) were greater than those of the corresponding treatments. for the first 15 days of fermentation period all treatments produced gas that have no methane and it containes co2, o2, <10ppm h2s and the balance atmospheric nitrogen, after 15 days of lage phase the digester starts producing methane. t2 produced more than other treatments in day 20. the average methane quality was high in t2 (49%) and t4 (45%). the other treatments it is between 33 to 41%. these significant variations in the amount, quality and rate of biogas production may be due to the feedstock difference (different concentration and amount of volatile solid) and difference in tempreture. 3.5. characterization of digestate (slurry ) one advantage of anaerobic digestion is the use of the digestate (slurry). to characterize the digestate tests were done two times and the mean values were indicated, total solid (ts) were 2.3%, 2.1%, 3.6%, 3.2%, 5.1%, 4.3%, 5.4 and 6.8% and volatile solid (vs) were 6.1%, 5.2%,12.5%, 11.3%, 13.2%, 12.4%, 15.1% and 14.7% for treatment t1, t2, t3, t4, t5, t6, t7 and t8. according to joenssen et al. (2004) anaerobic digestion only removes organics and the main mineral material and almost all nutrients remain in the bottom sludge, the result indicated that organics are decomposed. after digestion , the ph of the slurry were 5.5, 5.1, 5.4, 4.7, 4.2, 4.6, 4.5, 4.3. for t1, t2, t3, t4, t5, t6, t7 and t8 respectively. the ph of the slurry of t1-t4 were higher than other treatments that revealed the four treatments (t1-t4) were better in jemal beshir & abubake yimam ejssd, v 5 (2), 2018 89 © adama science & technology university https://ejssd.astu.edu.et 0 500 1000 1500 2000 2500 3000 3500 t1 t2 t3 t4 t5 t6 t7 t8 2700 3500 2600 3400 2700 2600 2500 2600 1107 1715 988 1530 945 1040 825 1040 41 49 38 45 35 40 33 40a m o u n t o f b io g a s (m l) treatment amount of bio gas amount of methane overall % methane methanoginesis procees (had high in conversion of acetic acid to methane). the solid digestate can be used for forage by mixing with flour of earth warms. figure 3. the total biogas, methane and its overall percentage of treatments 4. conclusion out of the total solid, the volatile solid (vs) were 69.2 80.8% indicating that large fraction of cactus is biodegradable and thus it can serve as an important feedstock for biogas production. less than one year old cactus and one year old cactus treated at 37oc (t2 and t4) give the highest quality biogas (49% and 45% ch4) the the other treatments. further research will be needed to confirm the high energy density of cactus for biogas production. the cactus biomass is highly organic that have less nitrogen, therefore it might need feed stocks which are rich in nitrogen, if used as substrate for biogas production. further investigation will be needed to confirm which nitrogen reach substrate is sutable for co-digestuion with cactus for optimum biogas production. acknowledgment the authers acknowledge center of energy technology and school of chemical and bio engineering aait/aau for laboratory facilities and wolkite university for financial support. reference ann, c.w. 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(2014). pretreatment of lignocellulosic biomass for enhanced biogas production. progress in energy and combustion science, 42, 35-53. http://www.sswm.info/library/1018 92 79 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper tuning thermal properties of beeswax incorporating zno, cuo and soot particles dinsefa mensur andoshe  , brook essay, osman ahemd, andualem merga, demeke tesefaye, nahom gezahegn, tariku miressa and tamirat merid department of materials science and engineering, school of school of mechanical, chemical and material engineering, adama science and technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 20 december 2019 received in revised form 25 february 2020 accepted 16 march 2020 phase change materials that have low thermal conductivity take a longer time to store and to discharge the stored thermal energy. the thermal conductivity of phase change materials can be enhanced using different additives. beeswax is a phase change material with a high thermal capacity and low thermal conductivity. therefore, the thermal conductivity, melting temperature, latent heat, and heat capacity of beeswax incorporating zno, cuo and soot particles with the 0.0, 0.064, 0.326, 1.304, and 3.260 g in the 20 g beeswax have been studied. the thermal conductivity measurement shows that the incorporation of zno, cuo and sootparticles improved the thermal conductivities of the beeswax, i.e., from 0.2502w/mk to 2.89w/mk. moreover, the differential scanning calorimetry measurements revealed that the melting temperature, latent heat, and heat capacity of the beeswax are decreased because of the incorporation of zno, cuo and soot particles. therefore, it is possible to tune the thermal properties of the beeswax incorporating metal oxide, soot particles to use beeswax-metal oxide/soot composite as a phase change materials. keywords: phase change materials latent heat thermal conductivities heat capacity 1. introduction phase change materials (pcms), as thermal energy storage systems, is receiving greater attention in recent decades for applications in heating and cooling. the pcms substances undergo a change in phase; solid to liquid or liquid to gas or vise-versa, they absorb large amounts of heat while maintaining constant temperature and discharge the absorbed heat when it needed. thermal energy can be stored either as a sensible heat (sh) or latent heat (lh). thermal energy is stored as sh while heating/cooling a liquid or solid storage medium. the amount of sh stored depends on the specific heat of the medium, the temperature change, and the amount of storage material (ioansarbu et al., 2018; ioan et al., 2019). a medium that stores sh in which the materials have a large temperature rise/drop when storing/releasing thermal energy. materials that store thermal energy as lh are pcms and they release or absorb the thermal energy while their physical state is changed. lh is mainly stored during the phase-change process in the isothermal condition and then it is related with the latent heat of the substance. lh storage system using pcms is an effective way to store thermal energy and has the advantages of high energy storage density and isothermal nature of the storage process. the stored lh can then be discharged at the desired rate which coincides with the melting temperature of the pcms.  corresponding author, e-mail: dinsefadear@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.167 http://www.ejssd.astu.edu/ mailto:dinsefadear@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxxxx dinsefa mensur et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 80 however, the main disadvantage of lh system is its low thermal conductivity, which mostly falls in the range of 0.2 w/(m⋅k) to 0.7 w/(m⋅k); therefore, effective heat transfer enhancement technologies must be adopted (ioansarbu et al., 2018). among the pcms materials beeswax is paraffin obtained from bees with the molecular formula of c15h31cooc30h61 (sara et al., 2015; lakshmi et al., 2016). the melting temperature of beeswax is in the range of 61-67°c (muhammad et al., 2017). the variation of the melting temperature of beeswax may be attributed to the impurities. beeswax has been studied for pcms; for example, it is used as a pcm material to maintain at an ambient temperature of the operating photovoltaic panels at high solar radiation and buildings (muhammad et al., 2017; thaib et al., 2018). the photovoltaic panel surface operating at high solar radiation has a surface temperature close to 49°c. however, when pcm material is applied on the surface of the solar panel, the surface temperature reduces to 34°c and the efficiency of the solar panels improves. the drawbacks of pcms materials are their low thermal conductivities that affect the rate of thermal energy storage, and the pcm materials exhibited a large melting temperature. usually, to improve the thermal conductivities of pcm materials, a metal oxide or metal particles have been incorporated/added in the pcms. the thermal properties of beeswax with addition of grapheme and cuo have been studied in previous work and the result showed that the thermal conductivity of the beeswax is enhanced (nandy et al., 2016; muhammad et al., 2017; chengjun et al., 2019). therefore, this article focus on tuning the thermal properties of beeswax by incorporating different metal oxide particles and comparing the obtained thermal properties of beeswax/metal oxide composites. the thermal properties of beeswax, such as thermal conductivities, heat capacities, and melting temperature, are studied incorporating zno, cuo, and soot particles. furthermore, the metal oxide and soot particles also analyzed using xrd to study the crystal structure and phase. 2. materials and methods 2.1. materials used the study used beeswax as its pcm material, along with zn(no3)2, cuso4, naoh, soot, deionized water and ethanol to synthesize metal oxide particles. the precursor used in this study were zn (no2) with purity of 96%, cuso4 and naoh with purity of 99.8 % which were purchased from central drug house (p) ltd india and ranchem industry, respectively. moreover, the thermal properties of beeswax/metal oxide composite were characterized by dsc-60 plus and qtm-500. furthermore, the crystal and phase of metal oxide particle were investigated using xrd-7000. 2.2. experimental procedure 2.2.1. preparation of zno, cuo and soot particles zno particles were synthesized by precipitation method using naoh and zn(no3)2 precursors (romadhan et al., 2016). the naoh and zn(no3)2 solution was prepared by adding 2.0 g of naoh in 50 ml and separately 14.875 g of zn(no3)2 precursor in 100 ml of deionizing water. both beakers containing the solution were heated up to 80°c with continuous stirring kept at 1000 rpm in temperature controlled magnetic stirrer for an hour. after the complete dissolution of zn(no3)2 and naoh in de-ionized water, the mixture was transferred to a single beaker and kept at constant stirring rate of 1000 rpm for two hours keeping the temperature at 80°c. the precipitated solution formed after two hours reaction was separated using a centrifuge to obtain zno and the obtained residue was washed several times with deionized water until all the traces of naoh were removed. then, the zno gel were dried in an oven at 250°c for about an hour. the cuo particles were prepared using the same methods with a bit modification from (nandy et al., 2016) with a precursor of cu(so4) and na(oh). the 16.0 g of cu(so4) was dissolved in 100 ml of distilled water and 4 g of naoh was dissolved in 150 ml of distilled water putting the beakers on the magnetic stirrer adjusting the string rate to 1000 rpm. after complete dissolution of cu (so4) and na(oh) in the di water the solutions was transferred to a single beaker drop by drop under constant stirring condition. final solution reaction was allowed to proceed for 2 hr, then after the solution was allowed to settle for an overnight and the supernatant solution was then discarded carefully. the precipitate was washed several times using distilled water to remove residual from the obtained cuo. finally, the obtained cuo gel was dried in oven for overnight at 80°c. the soot consisting of dinsefa mensur et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 81 agglomerated particles was collected from regular car exhaust. the brown color beeswax was purchased from adama city, ethiopia, and repeatedly washed to remove the dusts and impurities that may encounter during the collection and/or transportation. it was known that beeswax is insoluble in water and washing does not affect it except removing the impurities. 2.2.2. preparation of beeswax-metal oxide particle composite beeswax-metal oxide composite was synthesized by mixing a 20 g of beeswax with 0.0, 0.064, 0.326, 1.304, and 3.260 g of metal oxide particle using the ultrasonic device. the detail compositions of beeswax and metal oxide are presented in table 1. the beeswax-metal oxide composite was synthesized with the following procedure. the beeswax sample was melted at 66°c, which is a bit higher than the melting temperature of the beeswax, for 60 min. then, the synthesized metal particle using the precipitation method was added to the melted beeswax sample. the mixing of beeswax and metal oxide particle performed using an ultrasonic vibrator with a frequency of 40 khz at a temperature of 66°c to keep the sample in a liquid state. the vibration of the beeswax-metal oxide composite using ultrasonic sonicator continued for 2 hr., until the particles and beeswax mixed evenly. then, the melted beeswax-metal oxide composites were cast and let to dry in ambient condition; the obtained beeswax-metal oxide composites are shown in figure 2. the synthesized beeswax-metal oxide composite show a slight color changes comparing with bare beeswax. the observed color change is from brown to light brown for zno incorporation, from brown to light green for addition of cuo and from brown to black as shown in figure 2(a)-(n). table 1: amount of particles incorporated in the beeswax 3. results and discussion the synthesized metal oxide using precipitation methods and the collected soot powder from regular automobile were characterized by xrd. moreover, their crystallite size also calculated using scherrer’s formula as shown in equation 1. the obtained xrd data were matched with jcpds48, 1548 for cuo, and jcpds 36, 1451 for zno sample and they are polycrystalline as observed that the incident x-ray have diffracted from different planes as shown in figure 1. the synthesized cuo and zno also found to be monoclinic and wurtizte phases, respectively. the (111) and (111) plane peak intensity of cuo is higher than the intensity other planes, which suggested that the dominant growth direction could be (-111) and (111). the xrd spectra suggesting that the incident x-ray diffracted more on the (101), (100) and (002) planes from the wurtzite zno crystal, and the growth direction also dominated to (101) direction. moreover, the average crystallite size for the synthesized cuo and zno found to be about 30 nm and 35 nm, respectively. d= 𝐾𝜆(𝛽 cos 𝜃)-1…………….. (1) where “d” is the mean size of the crystallite/grain size, k is constant with the value about 0.9,𝜆 is x-ray wave length, 𝛽 is the line broadening at half the maximum intensity (fwhm) and 𝜃 is bragg angle. the xrd spectra of soot black powder, which is collected from car exhaust, is presented in figure 1(c). soot powder collected from different source is composed of a crystalline graphitic carbons (manoj et al., 2012; pradip et al., 2012). the peak position exactly resembles with the work of manoj et al. (2012). the crystallite size estimated using scherrer’s equation is about 40 nm. 3.1. thermal conductivity and melting temperature the measured thermal conductivities for the prepared beeswax-metal oxide composites are shown in figure 2. measurement of thermal conductivity of beeswax-metal oxide composites were conducted using quick thermal conductivity measuring (qtm). the thermal conductivities of the beeswax enhanced after cuo and zno particles were incorporated, however, the soot particles have slightly decreased the thermal conductivities of the beeswax. moreover, the amount of thermal conductivities enhancement of the beeswax also depend on the amount of metal oxide particle added in the beeswax matrix. s. no beeswax(g) particles(g) 1 20 0.064 2 20 0.326 3 20 1.304 4 20 3.260 dinsefa mensur et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 82 figure 1: xrd spectra of (a) cuo, (b) zno, and (c) soot powder collected from regular car exhausts more specifically, the thermal conductivities of beeswax after incorporation of 0.0, 0.064, 0.326, 1.304 and 3.260 g of zno particles became 0.2502, 0.45, 1.90, 2.5 and 2.89 w/mk, respectively. furthermore, after 0.0, 0.064, 0.326, 1.304 and 3.260 g of cuo particles are added to the 20 g of beeswax the thermal conductivities were measured as 0.2502, 0.4903, 2.221, 3.1004, and 3.9552 w/mk, respectively. moreover, after incorporation of 0.064, 0.326, 1.304 and 3.260 g of soot particle to the 20 g beeswax matrix, the thermal conductivities were measured as 0.2502, 0.3525, 0.7520, 1.3132 and1.749 w/mk, respectively as shown in figure 3. therefore, it is possible to deduce that the thermal conductivity of the beeswax can enhance by the addition of zno, cuo and soot participles. 3.2. melting temperature, latent heat and heat capacity the latent heat, heat capacity and melting temperature of beeswax-zno, beeswax-cuo and beeswax-soot composite with different mass metal oxide particle were measured using dsc. the dsc measurement reveals that addition of zno and cuo particles has decreased the melting temperature, latent heat and heat capacity of beeswax, however, the soot particles is enhanced the melting temperature, heat capacity and latent heat of the beeswax as shown on figure 4 and figure 5. more specifically, the measured melting temperatures of the beeswax-metal oxide composite were 65°c, 63.1°c, 62.2°c, 62.1°c and 61.8°c, when the mass of cuo particle were 0.0, 0.064, 0.326, 1.304 and 3.260 g, respectively. the zno particle also decreased the melting temperature of beeswax from 65°c to 63.2°c, 62.6°c, 62.5°c and 62.4°c when 0.0, 0.064, 0.326, 1.304 and 3.260 g is incorporated in the 20 g beeswax matrix, respectively. dinsefa mensur et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 83 figure 2: the beeswax-metal oxide composite with their thermal conductivity, (a) bare beeswax, (b)-(f) 20 g beeswax with 0.064, 0.326, 1.304 and 3.260 g zno composite respectively, (g)-(j) 20 g beeswax with 0.064, 0.326, 1.304 and 3.260 g of cuo, respectively and (k)-(n) 20 g beeswax with 0.064, 0.326, 1.304 and 3.260 g of soot, respectively. figure 3. measured thermal conductivities of beeswaxmetal oxide composites vs. mass. when soot particles with 0.0, 0.064, 0.326, 1.304 and 3.260 g are incorporated in the 20 g beeswax matrix, the melting temperatures were measured as 65°c, 64.8°c, 64.6°c, 64.2°c and 63.8°c, respectively. after the incorporation of metal oxide with the mass of 0.0, 0.064, 0.326, 1.304 and 3.260 g the latent heat of beeswax-metal oxide composite also recorded as 400, 350, 195, 125 and 105 kj/kg for cuo, respectively; 400 360, 340, 270 and 187.5kj/kg for zno, respectively and 400, 395, 360, 350 and 300 kj/kg for soot, respectively as shown in figure 4(b). figure 5 shows that when the heat capacity of beeswax-metal oxide composite with different mass of metal oxide (zno and cuo) increased, the heat capacity of the beeswax decreased. on the other hand, for soot particle, the heat capacity is enhanced when the amount of added mass in the beeswax matrix is increased. the heat capacity for beeswax-cuo composite is recorded as reduced to 2.301, 1.75, 1.23, 0.63 and 0.25 kj/kg°c for incorporation of 0.0, 0.064, 0.326, 1.304 and 3.260 g of cuo particles, respectively. furthermore, the heat capacity of beeswax-zno composite was decreased (from 2.301) to 2.119, 2.035, 1.242 and 0.994 kj/kg°c for 0.064, 0.326, 1.304 and 3.260 g of zno particles, respectively. moreover, the heat capacity of beeswaxsoot composite was also decreased (from 2.301) to 2.281, 2.175, 2.533, 2.0 and1.75 kj/kg°c for 0.064, 0.326, 1.304 and 3.260 g of soot particles, respectively. dinsefa mensur et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 84 figure 4: melting temperature and latent heat of beeswax-metal oxide composite. (a) melting temperature of beeswax-metal oxide composite vs. different mass of metal oxide particles (b) latent heat of beeswax-metal oxide composite vs. different mass of metal oxide particles. of cuo particles, respectively. furthermore, the heat capacity of beeswax-zno composite was decreased (from 2.301) to 2.119, 2.035, 1.242 and 0.994 kj/kg°c for 0.064, 0.326, 1.304 and 3.260 g of zno particles, respectively. moreover, the heat capacity of beeswaxsoot composite was also decreased (from 2.301) to 2.281, 2.175, 2.533, 2.0 and1.75 kj/kg°c for 0.064, 0.326, 1.304 and 3.260 g of soot particles, respectively. figure 5: heat capacity of beeswax-metal oxide composite. the enhancement of thermal conductivity and the decrease of the melting temperature, latent heat and heat capacity of the beeswax after incorporation of the metal oxide, zno, cuo and soot particle is due to the spillover effects of the thermal conductivities of zno, cuo and soot particles (turko et al., 2016; dahai et al., 2018). 4. conclusion the beeswax-cupric oxide, beeswax-zinc oxide, and beeswax-soot composite synthesized and the thermal properties were studied. the experimental result shows that the thermal properties of the beeswax can be altered by adding/incorporating additives like zno, cuo, and soot particles. it is also observed that by changing the number of additives in the beeswax the thermal property can be controlled. more specifically, the melting temperature of the beeswax can be adjusted between 65°c and 61°c depending on the point of interest/application, the thermal conductivity can tune between 0.4-4.0 w/mk, heat capacity can adjust between 0.2 to 3 kj/kg°c, and the latent heat between 105-430 kj/kg. reference abdolkarim, s., (2015) beeswax-colophony blend: a novel green organic coating for protection of steel drinking water storage tanks, metals, 5: 1645-1664 turko, b.i., kapustianyk, v.в., rudyk, v.p., rudyk, y.v. 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(2019). carbon soot/n– carboxylic acids composites as form-stable phase change materials for thermal energy storage, chemistry select, 4: 7108 –7115 dahai z., lingling w., wei y., huaqing x., (2018). intriguingly high thermal conductivity increment for cuo nanowires contained nanofluids with low viscosity, scientific reports, 8:5282 ioan, s., calin s., (2018). a comprehensive review of thermal energy storage, sustainability, 10: 191 ioan, s. alexandru, d., (2019). review on heat transfer analysis in thermal energy storage using latent heat storage systems and phase change materials, int. j. energy res., 43:29–64 sara, a., reza, p., mohammad, h. m., seyed, m. z., seyed, a. s., (2015) beeswax-colophony blend: a novel green organic coating for protection of steel drinking water storage tanks, metals, 5: 1645-1664 lakshmi , p., pavan k., manikumar , lakshmi a., satyapandu , phalguna r, v., (2016 ) formulation & evaluation of anti inflammatory cream by using nsaid’s drug with herbal extract of withania somnifera for the treatment of rheumatoid arthritis, world journal of pharmaceutical research, 5(4): 1858-1929 muhammad a., nandy p., engkos a. k., erwin p., rizky ,a,l., mahlia ,t.m.i., (2017 ). thermal properties of beeswax / graphene phase change material as energy storage for building applications, applied thermal engineering, 112: 273– 280 romadhan,m. f., nurgaha e. s., fahim, m. t.i, (2016). synthesis of zno nanoparticles by precipitation method with their antibacterial effect, indones. j. chem., 16 (2): 117 – 123 nandy, p., erwin, p., muhammad, a., (2016) thermal properties of beeswax/cuonano phase-change material used for thermal energy storage, international journal of technology, 2: 244-253 paulraj, r., pradip, k., ramavtar, m., chanchal, a., verma, a.k., bohidara,h.b., (2012). fluorescence behavior of non functionalized carbon nanoparticles and their in vitro applications in imaging and cytotoxic analysis of cancer cells, colloids and surfaces b: biointerfaces, 91: 34– 40 pradip kumar, h. b. bohidar, (2012) physical and fluorescent characteristics of nonfunctionalized carbon nanoparticles from candle soot, j nanopart res., 14:948 thaib, r., rizal, s., riza,m., mahlia,t.m.i., rizal,t.a., (2018). beeswax as phase change material to improve solar panel’s performance, materials science and engineering, 308 012024 razali, t., samsul, r., hamdani, t.m.i., mahlia, n., agung, p., (2018). experimental analysis of using beeswax as phase change materials, for limiting temperature rise in building integrated photovoltaics case studies, thermal engineering, 12: 223– 227 35 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper investigation of laser surface treatment on the microstructure and mechanical properties of alsimn alloy moera gutu jiru  and habtamu beri department of mechanical design and manufacturing engineering, adama science and technology, p. o. box 1888, adama, ethiopia article info abstract keywords: mechanical property laser remelting aluminum silicon this work investigates high-temperature properties of alsimn alloy after laser remelting by continuous mode co2 laser energy. substrate materials were prepared after solutionized heat treated at 510oc for 5 h followed by artificially aged at 160oc for six hours. the result of the finding showed high improvement in mechanical properties by 80% of heat-treated samples. the formation of fine dendrite microstructure, rode like larger secondary dendrite and sound metallurgical bonded morphology played a great role. the maximum laser modified thickness of 2.23 mm was achieved. 1. introduction the durability of engineering materials depends on both surface and bulk material properties, but most significantly, on surface properties. a good surface property enhances durability of the component by protecting the bulk material from external damages caused due to environments such as corrosion and any mechanical effects such as wear. al-si-cu-mg alloys are widely used to manufacture cylinder blocks and covers of the engine for small passenger cars because of their good strength at high temperature. long back et al. (1979) observed that the wear resistance of al-si alloys increases with increasing silicon content until the eutectic composition, i.e. 12 wt%. hwang et al. (2009) observed that addition of 0.45 wt% mg to type 319 aluminum alloy (al-6.7si-3.75cu) increased the strength of the alloy, although at the expense of ductility. the addition of manganese further improves the high-temperature strength of the aluminum alloys. manganese addition in al-7si-3.8cu-0.5fe alloys is usually used to neutralize the detrimental effects of   corresponding author, e-mail: jirata2010moti@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.134 al5fesi by transforming it to the -al13 (mn, fe)4 si2 phase (hwang et al., 2008). liao et al. (2017) developed high manganese aluminum alloy, al-12si-4cu-1.2mn by casting route. it displayed high ultimate tensile strength (more than 132 mpa) at 250c. apart from the high tensile strength for cylinder blocks, high surface hardness and good tribological behavior are also needed. laser surface melting (lsm) can be a potential process for improving the surface characteristics. lsm has been applied for improving the hardness of cast alloys as well as fabricating the product from the powder. in this process, cooling rates of the order of 105 to 108 k/s are obtained that helps in achieving the refined microstructure (sahoo et al., 2015). pinto et al. (2003) carried out lsm of al-15cu alloy and observed about three times increase in the hardness. abbas et al. (2006) carried out lsm of magnesium alloys, az31 and az61, using a 1.5 kw high power diode laser (hpdl). a significant improvement in the hardness and wear resistance was http://www.ejssd.astu.edu/ mailto:jirata2010moti@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.134 moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 36 observed with a grain size of about 5 m. zhang et al. (2008) enhanced the tribological properties of am50 magnesium alloy by lsm with a 2 kw continuous wave co2 laser. a significant improvement in microhardness and wear resistance was observed, although there was no significant effect on the coefficient of friction. cabeza et al. (2012) used lsm to repair the surface of a maraging steel, 14 ni (200 grade), in different heat treatment conditions using high power solid nd-yag laser. the effect of lsm on corrosion behavior has also been studied. conde et al. (2000) carried out lsm of austenitic, ferritic and martensitic stainless and observed an increase in the corrosion resistance provided the correct processing parameters were used. majumdar et al. (2003) observed that lsm of a commercial mg alloy, mez (zn 0.5%, mn 0.1%, zr 0.1%, rare earth elements 2%, mg remaining percentage), resulted in an increase of its hardness, wear-resistance and corrosion resistance. osorio et al. (2008) investigated the effect of lsm on the corrosion resistance of al-9si casting alloys. as-cast samples were remelted using a continuous 1 kw co2 laser. however, the corrosion resistance got reduced due to lsm. kang et al. (2016) carried out selective laser melting of mixtures of al-12 si alloy and si powders to improve the wear performance. the final composition achieved was al-18si. aboulkhair et al. (2016) improved the fatigue performance of selective laser melted alsi10mg alloy. laorden et al. (2017) reported selective laser surface melting of a356 and aluminum matrix composite reinforced with sic particles (a356/10% sic particles). several researchers investigated the polishing of the surface using laser irradiation. ukar et al. (2010) reported 90% surface roughness reduction after laser polishing of din 1.2379 tool steel using co2 and high power diode laser. the mean roughness value obtained was below 0.5 μm. pfefferkorn et al. (2014) reported the advantages of pulsed laser polishing of s7 tool steel. they observed that a larger melt pool diameter provided a smoother surface than the smaller one. (pfefferkorn, 2017) have presented interesting results on pulsed laser micro-structuring of the surface of ti-6al-4v alloy. this research is mainly focused to fill the gap that found from the research of hwang et al. (2008) and liao et al. (2017), in which laser surface treatment was not conducted. therefore, this work mainly focused on the investigation of laser surface treatment and studied the effect of laser power, scanning speed on micro-hardness and morphology of the modified surface. the main objective of this work is therefore to improve mechanical properties such as hardness and scratch resistance, and investigation of the effect of laser beam energy density on the depth of modified surface and micro hardness of laser modified surface. 2. materials and methods for this experiment work, samples were prepared in the dimensions of 160  55  10 mm3 using aluminum from the cast alsimn block. chemical composition (wt. %) of alsimn substrate before laser remelting is given in table 1. laser remelting was conducted along the width direction (55 mm), single bead without overlapping and multiples of beads formed on the same sample up to six beads processed by different laser parameters from 1.7 kw to 2.2 kw laser power, and from 300 mm/min to 550 mm/min laser scanning speed. the overall laser parameters used for the experiment are given in table 2. laser energy density was calculated from laser power, scanning speed and laser beam diameter. table 1: chemical composition (wt.%) of alsimn substrate before laser remelting after laser melting was completed, the metallographic study was conducted by cutting some portion of the laser-remelted region and polished in cross-section direction in order to observe both the remelted and substrate portion and to reveal the thickness of laser remelted region. after polishing with different silicon carbide emery sheets starting from 250, 600, 1200 and 2000 grades and final mirror, polishing was made by smooth cloth with the help of chemical sillvo. the mirror-polished samples were etched at room temperature using standard chemical solutions prepared from 1ml hf, 1.5 ml hcl and 2.5 ml hno3 in the solution of 95 ml purified water. the etching was made by rubbing the samples by applying chemicals on the mirror-polished surface using clean cotton, for 6–8 s, then washing with water to neutralize to avoid further wt.% si c fe mn mg cu al 11.03-12.01 0.21 1.02 2.5-3.5 0.2 0.13 84.91 moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 37 etching. the dried samples were observed by optical microscopy to investigate microstructure and grain size. the morphology of laser-remelted region was studied using the help of high-resolution electron microscopy called field emission scanning electron microscopy (fesem). in order to study the chemical composition after laser remelting both elemental mapping and weight percentage composition tests were analyzed using electron dispersive spectroscopy (eds) machine. different mechanical properties were studied after laser remelting was conducted. the hardnesses of laserremelted regions were measured by the vickers hardness testing machine by applying a 3 kg load along the cross-section of the polished surface. continuous multiple remelting beads without overlapping were carefully maintained on one side of the sample of 5 mm plate prepared from the 10 mm blocks. the tensile specimens were prepared by cutting a portion of lasertreated area by cutting using wire edm machine. the results of all the experiments were discussed in the result and discussion section. table 1 shows the chemical composition of the substrate material. laser energy density was calculated as follows (jain et al., 1981): , e v p d  where, p is laser power, v is scan speed and d is laser beam diameter. table 2: laser process parameters of laser remelting laser beam energy density (j/mm2) laser power (kw) laser scanning speed (mm/min) laser beam diameter (mm) 44.53 2.2 550 5.39 46.76 2.1 500 5.39 49.47 2.0 450 5.39 52.93 1.9 400 5.39 57.28 1.8 350 5.39 63.08 1.7 300 5.39 3. result and discussion in this section, the results of the all experiments were discussed in detail. the remelted layer thickness, microstructure, grain size, surface morphology and elemental mapping as well as tensile properties were investigated. 3.1. the remelted thickness figure 1 shows the cross-sectional view of laserremelted samples measured by digital microscopy. the top half-moon shape represents the remelted thickness and width in cross-section view. the remelting quality is sufficiently made without defects like cracks or unmelted conditions. the depth and width of a laser remelted layer thicknesses are presented in figure 2 (a, b). the effect of heat treatment on the geometry of laserremelted thickness was investigated. for samples processed with the same laser parameters, both the depth and width of remelted layers are more for unheated samples and less for solutionized heat-treated and artificially aged samples. as a laser energy density was increased from 44.53 j/mm2 to 63.08 j/mm2, the remelted depth was linearly increased for both samples. for heat-treated samples, the minimum depth was 1.14 mm and while the maximum depth was 1.77 mm. when laser energy density was maximum at 63.08 j/mm2. the remelted depth of untreated samples was nearly closed with heat-treated samples up to the energy density of 52.93 j/mm2 while after which it was increased and a maximum of 2.29 mm at high laser energy used. since heat treatment has improved the hardness of the material, after laser remelting less remelting thickness was measured than, unheated samples. figure 1: cross-section view of laser remelted samples processed by different laser energies, (x20); heat-treated sample 44.53 j/mm2 the response of heat-treated samples even at high laser energy was not very sensitive. the width of a laser remelted layers were 5.31 mm to 5.86 mm at low and high laser energies for heat-treated samples. while for untreated samples, the remelted layer was from 4.87 mm to 6.34 mm. heat treatment prior to laser treatment has improved the hardness of the material. the thickness of remelted region hardness indention marks moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 38 the laser-remelted surface plays a significant role to protect the surface from any damages such as wear and corrosion. in this regard, the more remelted layer thickness formed has more advantageous than less remelted layers thickness formed. to maintain sufficient thickness of laser modified surface requires a careful understanding of process parameters and applications of the material in which it works. in other laser surface modifications like alloying, this may be more costly due to the cost of alloying elements added to the base material. the variation of laser modified surface thickness was due to laser process parameters and heat treatment conditions. wong et al. (1997) reported laser remelting of aluminum alloy and indicated that remelted depth and width were increased with an increased in laser power density. figure 2: the effect of laser energy density on laser remelted thicknesses (a) and remelted width (b). 3.2. microstructure and grain size the properties of a material depend on the type of material and manufacturing technique used to produce the part. for metals and its alloys, the orientation and gain structure formed in the microstructure play a critical role. all improvements to make highperformance alloys have been under way for many decades. a laser surface modification like remelting the existing material is one method under attention. the microstructures of heat-treated and untreated samples after laser remelting in the same laser process parameters were compared. figure 3a shows the microstructure of laser heat-treated samples and figure 3b is microstructure before laser remelting. the grain structures are small and major alloying element silicon was revealed in the morphology as silicon rods and silicon plates (figure 3b). the smaller grain size formed was due to the heat treatment effect. since heat treatment by itself improves material properties by making a rearrangement of grain structure during heating followed by aging or cooling process. in this case, after solutionized heat treatment in an electrical furnace at 510oc for 5 h and artificial aging at a controlled temperature of 160oc for 6 h. this is an improvement in microstructure by alloying homogenous grain structure than unheated treated samples. figure 3: microstructure (a) after laser remelting and (b) before laser remelting 0.5 1 1.5 2 40 44.53 49.06 53.59 58.12 62.65 67.18 r e m e lt e d t h ic k n e ss ( m m ) laser energy density (j/mm2) (a) 2 2.75 3.5 4.25 5 5.75 6.5 40 44.53 49.06 53.59 58.12 62.65 67.18 r e m e lt e d w id th ( m m ) laser energy density (j/mm2) (b) silicon rods silicon plate (a) (b) moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 39 figure 4(a-f) shows the microstructure of heattreated samples after laser remelting. the microstructure formed was different when different laser energy densities were used. the dendrite microstructures were formed in different places for the same material processed by the same laser energy density. the dendrite grains formed from the interface and grow in the direction of the melt pool center along with the direction of solidification. figure 4(e, f) shows the direction of dendrite grows in the arrows head indicated. during laser remelting, the substrate portion absorbs more heat and dissipated along with its parts, so that it acts as a cooling initiator. the solidification starts from the interface and proceeds up the surface. the grain structure was very closely arranged and networks of small dendrite cells were formed when laser energy densities of 44.53 j/mm2, 46.76 j/mm2, and 49.47 j/mm2, as shown in figures 4(a, b, c). the dendrite structures were more lateral growth when the laser energy was started increasing from 52.93 to 63.08 j/mm2 as illustrated in figures 4(d, e, f). the high energy caused more remelted layer thickness deeper, so that the cooling rate was slower than, other samples processed by low laser energies. because of this effect, the dendrite arm structures got sufficient time to grow. this was visible in a typical microstructure shown in figure 4(f). during laser remelting and solidification processes, primary α-al and al-si eutectic structures of fine-grain structures were formed. because of a rapid solidification process, fine dendrite grains are formed near the top and at the center of remelted layers. the interface grain structure mostly contains secondary dendrite formations while haz has columnar grains. the dendrite arm spacing and grain sizes are dependent on cooling and solidification rates. rapid cooling enhanced fine microstructures of small grain sizes, small dendrite cells, which was visible in figure 4(f). the solidification starts from an interface and higher solidification rate achieved near the center and top portion. the top and center remelted regions have small grain sizes, small dendrite cells, and dendrite arm spacing than interfaceremelted layers. figure 4: microstructure of heat-treated samples after laser remelting at different laser energies (x40); (a) 44.53 j/mm2, (b) 46.76 j/mm2, (c) 49.47 j/mm2, (d) 52.93 j/mm2, (e) 57.28 j/mm 2 and (f) 63.08 j/mm2. (a) (b) (c) (d) (e) (f) small dendrites and grain size small dendrite arm spacing substrate region small dendrite cells dendrites in the center of remelted layers due to directional solidification branched of dendrites large grains and long dendrite secondary arms moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 40 0 5 10 15 20 25 30 35 40 45 50 44.53 46.76 49.47 52.93 57.28 63.08 a v e ra g e g ra in s iz e ( μ m ) laser energy density (j/mm2) the microstructure of heat affected zone was different from the laser remelted region. the columnar grain structures are formed due to heating effects without remelting. figure 5(a-b) shows a typical microstructure of heat affected zones for both heattreated and untreated samples after laser remelting. the grain sizes are bigger and different from laser remelted regions. there is no melting takes place, but due to heating effect, the grains are reallocated and formed large grains of secondary dendrites. the dendrite arm spacing was bigger in untreated samples than heattreated samples. figure 5: microstructure of (a) heat affected zone after laser remelting and (b) interface zone of laser re-melted heat affected zone (haz). figure 6 illustrates the average grain size of the laserremelted samples with respect to laser process parameters. the grain size of both heat-treated and untreated samples was compared which are processed by the same laser parameters. the results show the average grain sizes of unheated treated samples were bigger than heat-treated samples. at the minimum laser energy density of 44.53 j/mm2, average grain size was 26.45 µm and 30.23 µm, for heat-treated and untreated samples, respectively. for both samples, the maximum grain size was 29.78µm and 42.69 µm, formed at the maximum laser energy density of 63.08 j/mm2. this may be due to more energy created larger remelted layer thicknesses, and deeper remelted thickness so that cooling time is more. the cooling time of deeper remelted thickness was more than the cooling time of thin remelted thickness. a short cooling time or high cooling rate allows the formation fine microstructure of samples processed by less laser energy than theses processed by higher laser energies. the grain size of the heat-treated sample before laser remelting was 64.76 µm, while it was larger as 74.18 µm, for untreated samples. figure 6: the effect of laser energy density on average grain diameter after laser remelting the larger grain sizes were formed in the heataffected regions of both materials. the average grain size in haz for the heat-treated sample was 74.68 µm, while for untreated samples 81.42 µm. the grain sizes are visible as observed in the microstructure images. the formation of networks of small dendrite cells in the microstructure was clustered near the top remelted layers. the small grain sizes are formed at the center of the remelted layer while columnar grains are revealed near the interface region as bigger grain sizes. the fine microstructure will boost mechanical properties of the material like its microhardness and wear performances. haz (a) (b) moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 41 3.3. surface morphology and chemical composition the quality of laser-remelted samples was investigated from surface morphology conducted by fesem at higher magnifications. the presence of defects in the material affects performance and durability of the material and should be avoided. in order to evaluate the quality of laser remelted layer thickness of both heat-treated and untreated samples, a morphology study was conducted like the one given in figure 7(a, b) for heat-treated samples. the result confirms the sound metallurgical bonding formed during laser remelting. the connection of each grain with neighboring grains formed without forming defects like porosity and cracks. figure 8 shows elemental mapping after laser remelting. it confirms that silicon decomposition is about 13%. 3.4. investigation of mechanical properties the hardness in cross-section of remelted thickness was conducted and the effect of laser process parameters was investigated. the surface scratch test for evaluating deformation resistance of laser remelted samples was also discussed in this subsection. figure 7: the morphology of heat-treated sample after laser remelting at different magnifications (a) 100 k.and (b) 50 k figure 8: solutionized heat-treated sample after laser surface remelting of sample processed by 1.9 kw laser power. morphology of remelted region and composition (a ) (b ) moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 42 0 50 100 150 200 250 0 100 200 300 400 m ic ro h a rd n e ss ( h v 0 .3 ) distance from the top (µm) 0 50 100 150 200 0 200 400 m ic ro h a rd n e ss ( h v 0 .3 ) distance from the top (µm) 0 50 100 150 200 250 0 100 200 300 400 m ic ro h a rd n e ss (h v 0 .3 ) distance from the top (µm) 0 50 100 150 200 250 0 200 400 m ic ro h a rd n e ss ( h v 0 .3 ) distance from top (µm) 3.4.1 microhardness the hardness of the laser-remelted layer was measured in cross-section from the top of the laserremelted region to the substrate region (figure 1). the hardness of the laser-remelted region is much more improved than the substrate material. however, the hardness is not uniform throughout the remelted layer, which is because of the grain structure and orientation is different from the remelted layer. figure 9(a-d) shows the microhardness values of laser-remelted samples for both heat-treated and untreated samples in comparison. in order to observe the effect of laser energy density on the microhardness, six samples were processed by different laser parameters for heat-treated and untreated samples. the hardness of alsi material prior to laser remelting has an average hardness of 81.67 hv0.3 and 78.86 hv0.3, for solutionized heat-treated and untreated samples. the maximum microhardness of 175.35 hv0.3 for heat-treated samples near the top remelted region while untreated sample microhardness was 186.75 hv0.3. for the first two laser energy densities, the hardness of untreated samples was greater than heat-treated samples. however, when laser energy density was increased, the hardness of heat-treated samples is higher than in untreated samples. because of the heat applied is sufficient to make a hardening effect of heat-treated samples. for heat-treated samples after laser remelting, the maximum hardness of 203.59 hv0.3 was measured for samples processed by 49.47 j/mm2 laser energy densities. for a heat-treated sample, the maximum microhardness of 205.95 hv0.3 was achieved for a sample processed by 46.76 j/mm2. the effect of increasing laser energy density has a reduced hardness of both heat-treated and untreated samples. the minimum hardness was measured for samples processed by the maximum energy density of 63.08 j/mm2. this is because of the more energy used, caused deeper remelted thickness of the material, where the grain sizes were coarse. this was confirmed from the result of the average grain diameter discussed in the previous section. the hardness was more, nearly a little far from the top laser remelted layer thickness since the top portion was mainly aluminum. the hardness also randomly decreasing in laser remelted layer thickness towards the substrate material. heat-affected zone also shows improved hardness than the substrate material. figure 9: microhardness of laser remelted samples at different laser energy densities; (a) 44.53 j/mm2, (b) 46.76 j/mm2, (c) 49.47 j/mm2 and (d) 52.93 j/mm2 (a) (b) (c) (d) moera gutu and habtamu beri ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 43 4. conclusion in this piece of work, the laser surface melting of al12si-4cu-1.2mn alloy was successfully achieved. the dendrite microstructure and refined grain size provided, improved mechanical properties after laser surface melting. there was about a 2.5 times increase in the microhardness of heat-treated samples after lsm. heat treated samples also showed improved in mechanical properties. hardness was more, nearly a little far from the top laser remelted layer thickness since the top portion was mainly aluminum. the hardness also randomly decreasing in laser remelted layer thickness towards the substrate material. heat-affected zone also shows improved hardness than the substrate material. laser remelting has refined average grain size and improved microhardness. reference abbas, g., li, l., ghazanfar, u. and liu, z. 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(2008). effect of laser surface melting on friction and wear behavior of am50 magnesium alloy, surface and coatings technology, 202(14): 3175–3179. 41 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 antibacterial triterpenoid from the leaves extract of ehretia cymosa chaluma sori, ruth sahilu, gemechu gutu, hailemichael tesso, aman dekebo, teshome abdo and yadessa melaku * adama science and technology university, school of applied natural science, applied chemistry program, p. o. box 1888, adama, ethiopia. * corresponding author, e-mail: yadessamelaku2010@gmail.com abstract ehretia cymosa (boraginaceae) is an indigenous plant in ethiopia traditionally used against various diseases including toothache, tetanus, dysentery, gastric ulcers and skin diseases. in view of its traditional use, the leaves were successively extracted on maceration with n-hexane, etoac and meoh which gave extract yield of 15 g (3%), 2.63 g (0.5%) and 8.13 g (1.6%), respectively. the extracts were subjected to qualitative phytochemical screening and the results revealed the presence of phytosterols, flavonoids, terpenoids, phenols, glycosides, and alkaloids. the n-haxane extract, after silica gel column chromatography, yielded four compounds identified with ir and nmr as compound 1, α-amyrin (2), β-amyrin (3) and bauerenol (4). similar attempt made to isolate compounds from the etoac extract has led to the isolation of same compounds. compound 1 has not been reported from the genus ehretia. the extracts and compound 1 were tested for their antibacterial activity using paper disc diffusion method against two bacterial pathogens such as pseudomonas aeruginosa and staphylococcus aureus. the methanol extract displayed remarkable activity against p. aeruginosa with inhibition zone of 30 mm at 25 mg/ml. the result is significant compared with gentamicin (22 mm at 25 mg/ml) used as positive control. the antibacterial activity presented herein has demonstrated that all the extracts and compound 1 were active against all tested bacterial species with the methanol extract showed appreciable activity comparable with the standard drug. thus the present study corroborates the traditional use of the leaves of e. cymosa against bacteria. keywords: boraginaceae, ehretia cymosa, antibacterial activity, nmr, α-amyrin, βamyrin, bauerenol 1. introduction human beings have since time immemorial used plants for different purposes including as food, for flavor, cosmetic, dying clothes, and above all as medicine for treating a wide spectrum of diseases. many medicinal plant extracts have been reported for their biological activities due to the presence of secondary metabolites which act as defense against pathogens such as bacteria, fungi and also insects and plant eating animals. plants of the genus ehretia comprises of about 33 species distributed in africa and asia, with a few mailto:yadessamelaku2010@gmail.com chaluma sori et al. ejssd, v 5 (2), 2018 42 © adama science & technology university https://ejssd.astu.edu.et species in tropical america and the west indies. some species in the genus including e. ovalifolia and e. thyrsiflora were reported to have a variety of flavonoids including luteolin, apigenin, kaempferol, quercetin, quercetin 3 – o – α d arabinoside, kaempferol 3 – o –αd-arabinoside, quercetin-3-o-β-d glucopyranoside, hyperoside, kaempferol – 3 – o – β d-galactopyranoside, kaempferol3-o-β-d-glucopyranoside, kaempferol-3o-arabinosylgalactoside, and quercetin-3-oarabinosyl galactoside. phenolic acids including caffeic and cinnamicacid were identified from e. obtusifolia, e. thyrsifloraand e. ovalifolia (iqbal, 2005; yoshikawa et al., 1995).the genus is rich in triterpenoids with bauerenol, bauerenol acetate, α-amyrin, betulin, lupeol and betulinicacid reported from e.laevis, e. buxifolia and e. thrysiflora (thapliyal, and yadav, 2003; burkill, 1985). ehretia cymosa (boraginaceae) is an indigenous plant widely distributed in different parts of ethiopia where it is locally called game in amharic and hulaga, ulaga, garmi in afan oromo. a leaf infusion and leaf sap is traditionally used to treat fever and as laxative agent, respectively. the leaves are also traditionally used against tooth ache, hyperthermia, gastric ulcers, tetanus and dysentery. the use of the root juice as a wound healing property was also reported (maundu & tengnäs, 2005). despite the traditional use of this plant against various life threatening diseases, there is few scientific report in the literature that describes the chemistry and biological activities. hence in this paper we present the results of the isolation of chemical constituents and antibacterial activities of the leaves extract of e. cymosa. 2. material and method 2.1. plant material the leaves of ehretia cymosa (figure 1) was collected in march, 2018 from adama town, kachema, east shoa zone, oromia, ethiopia. the plant material was authenticated by shambal alamu and voucher specimen (001) was deposited at the national herbarium of addis ababa university. 2.2. extraction and isolation the air dried powdered leaves (500 g) of e. cymosa were extracted successively on maceration using each 2.5 l of nhexane, etoac and methanol for 72 hours at room temperature. each was filtered and concentrated under reduced pressure at 40oc using rotary evaporator to give their corresponding extracts. the n-haxane extract (3 g) was adsorbed and subjected to column chromatography over silica gel with n-hexane: etoac as eluent to furnish 21 fractions, each 100 ml. fraction 7, eluted with n-hexane: etoac (7:3), was re-chromatographed over silica gel column chromatography which gave four fractions, each 40 ml. the second fraction was identified as compound 1. fraction 6 which was eluted with n-hexane: etoac (4:1) was found to be a mixture of compound 2, 3 and 4. chaluma sori et al. ejssd, v 5 (2), 2018 43 © adama science & technology university https://ejssd.astu.edu.et figure 1. leaves of ehretiacymosa (picture taken by gemechu gutu from kechama) 2.3 phytochemical screening tests the n-hexane, etoac and meoh extracts were subjected to qualitative phytochemical screening for the presence secondary metabolites including alkaloids, saponins, flavonoids, phytosterols, phenols and glycosides were done following standard procedure (harborne, 2005; parekh & chands, 2008). 2.3.1. detection of alkaloids extracts from each solvent were dissolved separately in dilute hydrochloric acid and filtered. filtrate was treated with dragendroff’s reagent (solution of potassium bismuth iodide). formation of red precipitate confirms the presence of alkaloids. 2.3.2. detection of saponins froth test: the extracts were diluted with 20 ml distilled water and this was shaken in a graduated cylinder for 15 minutes. formation of 1 cm layer of foam confirms the presence of saponins. 2.3.3. detection of flavonoids alkaline reagent test: the extract was treated with few drops of sodium hydroxide solution. formation of intense yellow colour, which becomes colourless on addition of dilute acid, confirms the presence of flavonoids. 2.3.4. detection of phytosterols salkowski’s test: the extracts was treated with chloroform and filtered. the filtrate was treated with few drops of conc. sulphuric acid, shaken and allowed to stand. appearance of golden yellow colour indicates the presence of triterpenes. 2.3.5. detection of phenols ferric chloride test: the extracts were treated with 3-4 drops of ferric chaluma sori et al. ejssd, v 5 (2), 2018 44 © adama science & technology university https://ejssd.astu.edu.et chloride solution. formation of bluish black colour confirms the presence of phenols. 2.3.6. detection of glycosides the extract was hydrolyzed with dil. hcl, and then subjected to test for glycosides. modified borntrager’s test: the extracts was treated with ferric chloride solution and immersed in boiling water for about 5 minutes. the mixture was cooled and extracted with equal volumes of benzene. the benzene layer was separated and treated with ammonia solution. formation of rosepink colour in the ammonical layer confirms the presence of anthranol glycosides. 2.4 structural elucidation of isolated compounds the structures of the isolated compounds were elucidated based on data obtained from spectroscopic methods including ir and nmr. the spectral data were also compared with literature value reported for similar compounds. 2.5 studying antibacterial activities the extracts and isolated compounds from the leaves of e. cymosa were screened for their antibacterial activities in vitro (baker, 2005). the antibacterial activities were determined using agar disc diffusion method against s. aureusand p. aeruginosa. stock solution of the methanol, ethyl acetate, n-hexane extracts and compound 1 were prepared at concentration of 10 mg/ml using dmso. mha was stabilized at 45oc and seeded with 20 microliters inoculated of a 24hr nutrient broth cultured of the test organism. it was rolled in the palm to ensure uniformly spread on the agar and the test organism. this was aseptically poured into a petridish and allowed to set. then previously prepared filter paper discs were place onto the surface of the agar plate at equal distance from each other and 15 mm from edge of plate. the hole was filled with 1ml of the respective concentration of the test extract. the petridish was preincubated for 30 min and incubated at 37oc for 24 hr. bacteria culture was incubated at 37oc for 24 hr. diameters of the clear zones of inhibition was measured in millimeters. dmso and gentamicin were used as negative and positive control respectively. 3. result and discussion 3.1. phytochemical screening the n-hexane, ethyl acetate and methanol extracts of the leaves of e. cymosa were analyzed for the presence of secondary metabolites including alkaloids, phytosterols, flavonoids, phenolics, glycosides and saponin. results of the phytochemical screening. table 1 revealed that the n-hexane extract of the leaves of e. cymosa contains alkaloids, phytosterols and flavonoids while the etoac and methanol extract were found to have alkaloids, phytosterols, flavonoids, phenolics and saponin. chaluma sori et al. ejssd, v 5 (2), 2018 45 © adama science & technology university https://ejssd.astu.edu.et table 1. phytochemical screening of the leaves extracts of e. cym secondary metabolites methods/reagents extracts of the leaves of e. cymosa n-hexane ext etoac ext meoh ext alkaloids dragendroff’s + + + glycosides modified borntragers _ _ _ saponins froth test _ + + phytosterols salkowski’s + + + flavonoids alkaline + + + phenolics ferric chloride _ + + key: + present, absent the leaves of e. cymosa are rich in triterepenes and flavonoids (table 1). various reports showed that terepenes are used for the treatment of many diseases including cancer, malaria, inflammation, and a variety of infectious diseases including viral and bacterial (lewis & avioli, 1991). numerous literature reports showed that flavonoids had remarkable antibacterial activity (cushnie & lamb, 2005). hence the presence of these metabolites in the nhexane, etoac and meoh extracts of the leaves of e. cymosa likely accounts the traditional use of this against bacterial infection. 3.2. characterization of isolated compounds in the course of this work four compounds were isolated from the hexane extract of the leaves of e. cymosa. herein is the characterization of these compounds. ho ho ho 2 3 4 ho o 1 figure 2. structures of compounds isolated from the leaves extract of e. cymosa chaluma sori et al. ejssd, v 5 (2), 2018 46 © adama science & technology university https://ejssd.astu.edu.et compound 1 compound 1 was isolated as a white solid melting at 172oc. the tlc showed spot at rf 0.43 with n-hexane:etoac (4:1) as a mobile phase which was visualized after dipping in vanillin /h2so4. the ir spectrum of compound 1 showed absorption band due to hydroxyl stretching at 3375 cm-1. the band due to c-h stretching of an alkane is evident at 2900 cm-1. the 1h-nmr spectrum (400 mhz, cdcl3, appendix 1) showed proton signal at δ 3.24 (1h, m) accounted for the presence of proton on carbon bearing oxygen. the singlet signal appearing at δ 3.20 is likely due to the proton on oxygen. this supports the ir spectrum of compound 1 for the presence of aliphatic hydroxyl group. the 1hnmr spectrum also displayed five singlet proton signals on methyl groups at δ 0.72, 0.80, 1.12, 1.13 and 1.25 ascribed to the presence of five methyl groups on quaternary carbon. also observed signals due to methyl groups are evident at δ 0.67, 0.85 and 0.91. the presence of seven methyl groups in the 1h-nmr spectrum partly assures the presence of triterpenoid skeleton in the structure of compound 1. the remaining proton signals were also observed in the aliphatic region. the proton decoupled 13c-nmr spectrum of compound 1 (appendix 2) with the aid of dept-135 (appendix 3) showed the presence of 30 carbon resonances of which six are due to quaternary, nine methylenes, seven methines and eight methyl groups. this indicates that the compound contain triterpenoid skeleton which supports the assertion of the 1h-nmr spectrum. the quaternary carbons were observed at δ 77.2, 64.1, 39.8, 38.8, 38.3 and 35.1.the 13c-nmr spectrum also showed methylene signals at δ 37.5, 36.7, 31.5, 30.9, 29.0, 27.3, 23.2, 22.9 and 16.0. the presence of an oxygenated methine carbon is apparent at δ 78.8 (c-3). the spectrum also displayed signals due to an oxygenated quaternary carbon at δ 77.2 and 64.1. the latter two signals are likely due to the presence of an epoxyidized carbon. the 13c-nmr spectral data of compound 1 was compared with the nmr data presented in the literature for α-amyrin with the result depicted in table 2. comparison of the 13c-nmr spectral data of compound 1 (table 2) with the data reported in the literature for αamyrin was found in good agreement except for the fact that the signal due to the olefinic carbons (c-12 and c-13) of α-amyrin were too shielded in compound 1. this clearly indicates epoxidation of c-12 and c-13. the data generated well suited with a triterpenoids whose structure is depicted in figure 2. compound 1 has not been reported from the genus ehretia. chaluma sori et al. ejssd, v 5 (2), 2018 47 © adama science & technology university https://ejssd.astu.edu.et table 2. 13c-nmr spectral data of compound 1 and literature reported for α-amyrin position 13c-nmr spectral data of 1 data reported for α-amyrin (liliana, h.v. et al., 2016) 1 37.5 38.7 2 31.9 28.7 3 78.8 79.6 4 36.7 38.7 5 53.9 55.1 6 18.4 18.4 7 32.2 32.2 8 37.6 40.7 9 49.1 47.7 10 35.1 36.6 11 23.5 23.3 12 64.2 124.4 13 72.2 139.5 14 44.7 42 15 27.7 27.2 16 27.3 26.6 17 34.9 33.7 18 56.0 59.00 19 38.3 39.6 20 38.8 39.6 21 31.9 31.2 22 39.8 41.5 23 30.9 28.1 24 15.3 15.6 25 15.4 15.6 26 16.9 16.8 27 23.2 23.2 28 29.0 28.1 29 17.9 17.4 30 21.3 21.4 chaluma sori et al. ejssd, v 5 (2), 2018 48 © adama science & technology university https://ejssd.astu.edu.et fraction 6 fraction 6 (500 mg) was obtained as a white solid melting at 180-181oc. the tlc profile showed spot at rf 0. 57 with hexane:etoac (4:1) as a mobile phase which was visualized after dipping in vanillin/sulfuric acid. the ir spectrum of fraction 6 revealed the presence of hydroxyl stretching at δ 3380. the absorption band observed at δ 2932 is accounted to the presence of c-h stretching of a hydrocarbon. as observed from the 1h and 13c-nmr spectrum, fraction 6 is a mixture comprising of three triterpenoids. purification using silica gel column chromatography was failed as the fraction showed same spot on tlc. further attempt to purify this fraction using recrystallization was not successful. therefore qualitative identification of these compounds in fraction 6 was done using nmr spectrum. the proton decoupled 13c-nmr spectrum of fraction 6 showed the presence of six well resolved carbon signals in the olefinic region. the signals observed at δ 124.3 and 139.6 are characteristics of α-amyrin (liliana et al, 2016). on the other hand the olefinic signals due to β-amyrin were evident at δ 121.7 and 145.3 (liliana et al, 2016). also observed in the olefinic region is a signal at δ 116.4 which is characteristics of bauerenol (sathish, et al, 2017).these indicate that fraction 6 is likely a mixture comprising of α-amyrin (2), β-amyrin (3) and bauerenol (4). in agreement to this is the appearance of three signals in the oxygenated region at δ 79.2, 79.0 and 77.2 which are characteristics of c-3 of α-amyrin, β-amyrin and bauerenol, respectively (liliana et al, 2016; sathish et al, 2017). furthermore the nmr spectrum clearly showed the presence of peaks characteristics of these compounds. therefore the data generated agreed with the structures depicted in figure 2 for compound 2, 3 and 4. 3.3 antibacterial activity of extract of ehretia cymosa the n-hexane, ethyl acetate, methanol extract and compound 1 were assessed for their antibacterial using agar well diffusion method activities against p. aeruginosa and s. aureus. all the extracts exhibited activity against p. aeruginosa and s. aureus (table 3). the zone of inhibition observed by the ethyl acetate extract against p. aeruginosa and s. aureus was found to be 16 mm and 13 mm at 25 mg/ml, respectively. the zone of inhibition observed by compound 1 against s. aureus was found to be 11 mm at 10 mg/ml. the zone of inhibition observed by the n-hexane extract against s. aureus was found to 13.5 mm at 25 mg/ml. on the other hand the methanol extract displayed remarkable zone of inhibition (30 mm at 25 mg/ml) against p. aeruginosa. this is significantly higher than the activity displayed by gentamicin (22 mm at 25 mg/ml) against same bacterial pathogens. the wide zone of inhibition of the methanol extract of e. chaluma sori et al. ejssd, v 5 (2), 2018 49 © adama science & technology university https://ejssd.astu.edu.et cymosa showed that it had great potential as a remedy for diseases caused by bacterial pathogens. furthermore the antibacterial agent of the leaves of e. cymosa is likely residing in the polar fraction of the extract. the results displayed herein showed that the extracts showed better antibacterial activity against gram negative as compared to gram positive bacteria. the antibacterial activities displayed by the extracts of the leaves of this plant may be useful to prevent the occurrence of infections or treat opportunistic infections that may occur as a result of different infectious diseases in humans. table 3. zone of bacterial growth inhibition (mm) for extracts and compound 1 samples con. in mg/ml zones of inhibition s. aureus p. aeruginosa n-hexane extract 25 13.5 7.0 etoac extract 25 13.0 16.0 meoh extract 25 10 30.0 compound 1 10 11 9.0 gentamicin 22 22 4. conclusion in conclusion, the presence alkaloids, phytosterols, flavonoids, phenolics and saponin in the extracts of the leaves of e. cymosa is significant as they may account for the traditional use of the species. silica gel column chromatographic fractionation of the n-hexane and etoac extract has led to the isolation of four triterpenoids identified as α-amyrin (2), β-amyrin (3), bauerenol (4) and compound 1. the latter compound was not yet reported from the genus. the work presented herein also demonstrated that the extracts and compound 1 had antibacterial activity with the methanol extract displayed pronounceable activity compared with the positive control. 5. acknowledgment the authors are grateful to adama science and technology university for the grant. reference baker, j.t. (1995). natural product drug discovery and development: new perspectives on international collaboration. j. nat. prod, 58, 1315 – 1357 burkill, h.m. (1985). the useful plants of west tropical africa. 2nd edition. volume 1, families a–d. royal botanic gardens, kew, richmond, united kingdom.960 pp. chaluma sori et al. ejssd, v 5 (2), 2018 50 © adama science & technology university https://ejssd.astu.edu.et cushnie, t.p., & lamb, a.j. (2005).antimicrobial activity of flavonoids, international journal of antimicrobial agents, 26, 343–356 harborne, j.b. (1973). methods of plant analysis. in: phytochemical methods. chapman and hall, london. iqbal, k., nawaz, s.a., malik, a., riaz, n., mukhtar, n., mohammad, p., choudhary, m.i. (2005). isolation and lipoxygenase-inhibition studies of phenolic constituents from ehretia obtusifolia. chem biodivers, 2, 104-111. lewis, w.h., & avioli, l.v. (1991). leaves of ehretiacymosa (boraginaceae) used to heal fractures in ghana increase bone remodeling, economic botany, 45(2), 281– 282 liliana, h.v., javier, p., & arturo, n.o. (2016).the pentacyclic triterpenes α, βamyrins: a review sources and biological activities. international journal of advanced robotic activities systemsnews, 1-17. maundu, p., & tengnäs, b. (2005).useful trees and shrubs for kenya.world agroforestry centre east and central africa regional programme (icraf-eca), technical handbook 35, nairobi, kenya.484 pp. parekh, j., and chands, s. (2008). phytochemical screening of some plants from western regions of india, plant arch, 8, 657 – 662 thapliyal, p.c., & yadav, s.k. (2003). a new naphthoquinone from aerial parts of ehretia laevis.j. inst. chem. india, 75, 13-15. sathish, k., p., viswanathan, m.b.g., venkatesan, m., and balakrishna, k. (2017). bauerenol, a triterpenoid from indian suregada angustifolia: induces reactive oxygen species–mediated p38mapk activation and apoptosis in human hepatocellular carcinoma (hepg2) cells. tumor biology, 39(4), 1010 yoshikawa, k., kageyama, h., arihara, s. (1995). phenolic glucosides and lignans from ehretia ovalifolia, phytochemistry, 39, 659-664 news:1-17 103 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper engineering geological investigation of adama town: implication to engineering practice yadeta c. chemeda  department of applied geology, school of applied natural science, adama science and technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 3 february 2020 received in revised form 29 june 2020 accepted 26 august 2020 adama was founded hundred years ago and is one of the major and densely populated towns in ethiopia. it is located 100 km south–east of addis ababa and the hub of a vast region of immense economic potentials accessible by means of rail way and expressway. due to the mentioned reasons, the urbanization is rapid. however as in many towns of ethiopia, very little is known about the engineering properties of soils and rocks underlying the town. moreover, the town is located in the southern extreme of the active volcano-tectonic segment of the northern main ethiopian rift (mer). the present research work is, therefore, aimed at assessing and evaluating the geological and engineering geological condition of the rocks and soils of the town. detailed field investigation, in-situ rock strength test and laboratory tests were carried out. a total of 30 soil samples were taken from 16 test pits, which were dug manually to 3 m depth. the natural moisture content of the soil of the study area ranges from 6.34% 25.2%, liquid limit 26.06% 54%, plastic limit 7.5% 40.83%, plasticity index 2.22% 26.83%, free swell 0% 40%, specific gravity 2.12 2.67, and ph 4.48 6.7. low to medium plastic silty sand and sand are the dominant soil type in the study area. the rocks of the study area were classified into low strength, medium strength and high strength rock mass units based on the strength (unconfined compressive strength) of intact rock and discontinuity characteristics. gully erosion, land slide, seismic activity and flooding are the main geo-hazard that need attention in the study area. keywords: adama geological engineering geological engineering practice 1. introduction adama was founded hundred years ago and is one of the major and densely populated towns in the region and in ethiopia as well. it is located about 100 km south– east of addis ababa and at the heart of both ethiopia and the national regional state of oromia as well. the town is the hub of a vast region of immense economic potentials accessible by means of railway and expressway. due to these facts, the urbanization is rapid in the different directions of the town and investors are attracted to invest in the town and the nearby areas. currently, many civil engineering structures such as  e-mail: yadeta.chimdessa@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.281 roads, bridges, industry park and multistory buildings including international hotels and commercial centers are under construction in the town. on the other hand, the town has been vulnerable to geological hazards like erosion and associated landslides, ground fissure and flooding during rainy season. these hazards caused damages to dwelling houses, roads, bridges, farm land and other infrastructures like power and communication lines due to unplanned expansion of the town. in addition, the town is situated in a seismically active area, main ethiopian rift (mer), where there is active http://www.ejssd.astu.edu/ mailto:yadeta.chimdessa@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020................ yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 104 internal tectonic movement as evidenced by recent ground crack in the southern part of the town. site investigation is a prerequisite for the successful and economic design of civil engineering structures (bell, 2007). in other word, deep knowledge of the geomorphological, geological and geotechnical condition of an urban area is necessary to provide basic information about the ground conditions to local authorities, engineers and contractors (bowles, 1996). in addition, unplanned expansion of towns can exposed people and economic assets to the risk of natural disaster. despite the rapid urbanization and construction activity in adama town, no work was done in engineering-geology aspects. regional geology of the area, the rift in general, is covered at a very small scale (wolde gabriel et al., 1990; morton et al., 1979, etc.) which provide limited information for engineering applications. asfaw erbelo and hassen shube (2019) mapped the faults around adama and assessed their activity and potential to trigger earthquake. dejene tesema et al. (2017) investigated the flood hazard risk in adama town using analytical hierarchical process (ahp) and multicriteria approach. according to their finding, 10.4% of the total area of the town, which composed of different urban land uses, lies within high flood hazard zone. the only research to be mentioned in geotechnical aspect is the work of dagnachew debebe (2011), in which he has studied some of the engineering properties of soils of the town. however, the work missed some important details viz. geomorphological, structural, geo-hazard and geological information. more importantly, the engineering properties of rocks is not investigated and the engineering geological map of the town has not produced as well. an engineering geological map is the best way to depict the natural environment for engineering purpose (iaeg, 1981; bell, 1987). medium to large scale geological and engineering geological maps and data are widely used for urban land use planning, engineering site selection and other related works. the present work is, therefore, aimed to obtain information on the type, characteristics and distribution of rocks and soils and geodynamic conditions by integrating engineering geological and geotechnical investigation. 2. methodology 2.1. description of the study area the study area, adama town, is located in the main ethiopian rift, east showa zone of oromia national regional state (figure 1). geographically, the town is located between 52500 to 534000 m e longitude and 937000 to 950000 m n latitude. the town is 100 kilometers far from addis ababa along the road that connects addis ababa with eastern towns of the country and djibouti port. according to the climatic zones of ethiopia, the study area with an altitude ranging from 1500 2000 m above mean sea level is classified as subtropical climate. it receives maximum rainfall during summer season (i.e. july and august). topographically the area is situated in graben which is bounded by fault escarpments in western and eastern directions. the study area is characterized by flat to gently slope which ranges from 0° to 64°. all the streams flow into the depression bounded by fault. there is no perennial river and the peak discharge from intermittent surface runoff is attained during summer. 2.2. desk study and reconnaissance survey exhaustive and thorough systematic literature review with regard to site investigation, description and classification of soil and rock for engineering purposes, procedures for engineering geological mapping, similar and related works in the world, ethiopia and particularly in the study area was done. similarly, a review on unpublished and published geological map and geodynamic processes was done. later conceptual frame work and general methodology was developed from the knowledge acquired through literature review. in order to understand the general conditions of the study area such as topography, soil distribution, land slide manifestations, information was gathered and field reconnaissance survey was undertaken. the first reconnaissance field survey was done from may 08/2017 to july 5/2017 and during this field survey, some preliminary geological mapping, geomorphological and land form assessment and soil distribution identification were done. 2.3. detailed field survey and sampling in this stage, detailed field description of rock and soils, in-situ strength tests and soil sampling were carried. different traverses were made along rock and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 105 figure 1: location map of the study area soil exposures in different parts of the study area for identification and mapping of lithological units. surface mapping of geological structures was undertaken by measuring orientations (dip and dip directions) of discontinuities using brunton compass. similarly, conditions of discontinuity such as joint roughness, aperture, infill and weathering conditions were visually estimated on the field. in selected rock outcrops, the unconfined compressive (ucs) rock strength was estimated by using a digital schmidt hammer (n-type). a minimum of twelve schmidt hammer rebound value was applied perpendicularly on fresh exposed rock surface and joint wall at each rock outcrops. the test was conducted according to the standard suggested by barton and choubey (1977) and isrm (1978) as follow: schmidt hammer rebound value on fresh and unweathered rock surface was recorded, the rebound value ordered in ascending order and then discard the first four lower values and take the average of higher value. representative soil samples were collected from 16 test pits (figure 2) which were excavated up to three meter depth. visual description and soil sampling were carried out at two different depths (1.5 m and 3 m). due to the nature of the soil, only disturbed soil samples were taken for laboratory tests. the soil samples were kept in plastic immediately after sampling to keep their natural moisture content and then brought to laboratory. 2.4. laboratory tests laboratory testes where conducted to determine index properties of soil such as atterberg limit (liquid limit, plastic limit and plasticity index), soil gradation and other parameters of soils (moisture content, specific gravity, free swelling, ph). laboratory tests were done according to astm standards as summarized in table 1 in adama science and technology university geotechnical laboratory. table 1: laboratory tests and standards laboratory test type number of samples standard moisture content 30 astm d-2216 sieve analysis 30 astm d-421 liquid limit (ll) 30 astm d 4318 plastic limit (pl) 30 astm d 4318 free swell 30 astm d-4546 specific gravity (sg) 30 astm d-854 ph 16 astm d-4972 yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 106 figure 2: test pit locations 3. results and discussion 3.1. geology of the study area the study area is covered by quaternary sediments and different types of volcanic rocks which includes, scoria, rhyolite, basalt, volcanic ashes, pumice and ignimbrite. 3.1.1. quaternary deposits the recent sediments in the study area consist of alluvial, colluvial and residual soils. the residual deposit are common along the gentle slopes on the top of the ridges. these residual soils are derived from insitu weathering of volcanic rocks such as ignimbrite, basalt and volcanic ashes with pumice. the thicknesses of these units vary from about 0.5 to 0.8 meter, so for the current purpose it is mapped as a bedrock. colluvial deposits are common along foot of steep slopes (east and west of the town) and are not mappable. alluvial deposit is widespread and mainly exposed in the central, northern and southern part of the town (figure 3). it is light gray to brown in color, loose to dense and in some places it is stratified. 3.1.2. scoria the scoria rock unit is exposed in south-eastern part of the study area (figure 3) as systematically distributed scoria cone. it is highly vesicular and has porous and very rough surface. the nature of exposure of scoria cones varied from place to place where it is mainly vesicular and red in color. but in some places it is exposed as gray in color. this variation in exposure color could be related with oxidation reaction intensity of the rock with the available atmospheric oxygen. 3.1.3. rhyolite the rhyolite rock unit is one of the fine grained extrusive volcanic rocks. it is exposed in the south-east and south-west part of the study area as a volcanic ridge. it is fresh to slightly weathered and at some places it is interlayered with obsidian. it is felsic in composition and light in color. this rock unit is fractured by two sets of joints (ne and se striking), which are dominantly vertical, and fault. 3.1.4. basalt this rock unit is another type of extrusive volcanic rock and texturally fine grained and vesicular. the fine yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 107 grained basalt is exposed in the north-west part of the study area. while the vesicular basalt is exposed at south-western and central part of the study area. it is mafic in composition and light gray in color. it is slightly to medium weathered. it is fractured and jointed (both horizontally and vertically). it is exposed as steep cliff along fault scarp. some of the vesicles of vesicular basalt are filled by secondary materials (silica or calcite). figure 3: geological map of the study area (the scale is reduced from 1:10000) and geologic cross-section b a b a yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 108 3.1.5. volcanic ash this rock unit is a type of pyroclastic rock (pyroclastic fall) and covered large part of the study area (figure 3). the volcanic ashes rock unit is loose, fine to coarse grained and found at eastern, northern, northwestern, southern and south-western sides of the study area. it is well exposed along deep stream/river cut gullies. it is light brown in color. an alternating thin layer of pumice is common in this lithological unit. at some places it is very difficult to differentiate this deposit from alluvial soil. 3.1.6. ignimbrite this rock unit is found dominantly in the eastern and western part of the study area along a fault scarp (figure 4). in some places it is interbedded with paleosol layers, indicating frequent breaks in the volcanic activity. it is characterized by stretched glassy ‘fiamme’, showing a pantelleritic composition and by abundant basaltic lithic fragments. it is felsic in composition and the color varies from brownish to greenish. it is jointed both horizontally and vertically. 3.2. geological structures the geological structures of the study area are identified both from desk study using landsat image, dem and followed by later field checks. the dominant geological structures found in the study area are brittle type structures such as faults and joints. the study area is located within most active region of the mer ((ebcs, 1995)) which is affected by a series of parallel normal fault. specifically, the adama town is found in wonji fault belt, which is rift floor concentrated younger fault. in the field the fault is identified from physiographic features such as sharp cliffs which face towards the rift. in the west and south of the town, it forms narrow horest and graben structures. the overall orientation of the fault in the study area ranges from n-s to nne-ssw strike (figure 3) and mainly vertical. the joints are the second common geological structure observed on all types of rocks found in the study area except volcanic ashes/pumice and scoria. about 117 joint orientation measurements and characterization are conducted at different part of the study area for the regularly oriented joint systems. most of the joints are vertical (steeply dipping) and parallel to the local faults. the major joint sets observed are n to ne strike. not only this common range of structural orientations, but also there are some exceptional nw and e-w striking joints as shown on rose diagram (figure 4). figure 4: rose diagram of joints 3.3. geomorphologic process and geo-hazard erosion, volcanism and tectonic structures are the major and common geomorphologic processes identified in the study area. on the other hand, earthquake, landslide and flooding are some of the geological hazards observed or expected in the study area. 3.3.1. erosion erosion is the detachment and removal of soil and rock by the action of running water, wind, flowing ice, and mass movement and the relationships between the factors which influence erosion is extremely complex (selby, 1993). it is the function of erosivity (what factor causes erosion) and material erodibility (the susceptibility of geological material to erosion). the main causes of erosion in the study area are: the presence of steep slope (fault escarpment and volcanic ridges), seasonal intense rainfall and soft geologic materials (like volcanic ashes and alluvial soil deposit). the runoff from high land erode the soil from top of ridge and slope (sheet erosion) and spread the sediment on flat land. the other common types of erosion in the yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 109 study area is gully erosion. it formed deep gorges (gully) in different part of the town along drainage line by eroding loos soil and ash deposits. it posed major problem on land use of the town by modifying the land scape (figure 5). construction of cheek dams and gabions can considerably reduce the erodabilty and further increase of width of gully. figure 5: partial view of active gully erosional features in southern (top) and south western (bottom) part of the town 3.3.2. volcanism and geological structures the common types of landforms formed by volcanism in the study area are volcanic ridge and systematically distributed scoria cones and cliff (steep slope). the main ethiopia rift (mer) which started to develop in miocene time is part of the east african rift system (ears) and comprises a series of rift zones extending over a distance of about 1000 kilometers from the afar triple junction (boccaletti et al., 2000). as part of the mer, the topography of the study area is affected by the nne-ssw running fault sets, which are responsible for the formation of the different landforms, especially for the nne-ssw trending cliff (escarpment), horst and graben. the section is also characterized by complex extensional tectonics features manifested with associated quaternary volcanic outpourings. 3.3.3. earthquake an earthquake is the vibration of earth produced by the rapid release of energy and it is the most devastating earth process. according to bolt (1988), the important step in geological assessment of earthquake hazard of a site is the location and mapping of all geological structures and ascertainment of whether they are active or not. the study shall also include the assessment of soil condition and likelihood of landslides, subsidence, and liquefaction. concerning the location, the study area is located in the southern extreme of the active volcanotectonic segment of the northern mer and in zone 4 of the seismic hazard map (ebcs, 1995). the design ground acceleration for the study area (zone 4) is considered to be 0.1g for 100 year return period. the study area also dominated by nne-ssw striking extensional related normal faulting. the geomorphological features of the fault scarps reveal the normal faults in the study area are active (asfaw erbelo and hassen shube, 2019) requiring due attention when evaluating seismicity. liquefaction is the loss of strength of saturated loos cohessionless soils due to pore water pressure build-up during earthquake shaking. liquefaction commonly occur in loos coarse grained (cohessionless) soil and at depth shallower than 15 m (i.e. shallow ground water). even though the soil of the study area is dominantly coarse grained soil (silty sand and sand), which is susceptible to liquefaction, liquefaction hazard in the study area is less probable as the groundwater table is located at a great depth (> 150 m). 3.3.4. land slide slope movement can be classified based on mode and rate of movement, the shape of sliding plane, type of sliding material and other criteria (bell, 2007). from different types of slope movement, debris slide is observed in the north-east part of the study area on the fault scarp and ridge (figure 6) in which fragmented rock (debris) slide down slope. intense fracturing, weathering and human interference (quarrying at the base of ridge) are causative factors. 3.3.5. flood floods represent one of the most threatening types of natural hazards. however, the likelihood of flooding is more predictable than other types of geological hazards (bell, 2007). the geomorphological characteristics (presence yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 110 figure 6: land (debris) slide in the north-east part of the study area of numerous steep slope faults scarp and volcanic ridges) make the adama town vulnerable to flooding hazard during rainy season. flooding in adama town is an after effect of high precipitation (which is more common during summer), clogged canals (due to improper waste disposal), and poor drainage. according to dejene tesema et al. (2017), 10.4% of total area of the town, which composed of different urban land uses, lies within high flood hazard zone. in addition, 32,670 residents are living in flood risk zone and 867.6 ha of land functioning for different land uses (176.1 ha industrial, 571.1 ha residential, 120.4 ha mixed built up, and 1.8 km paved road) are located in high flood risk zone. 3.4. index properties and classification of soils 3.4.1. natural moisture content the natural moisture content, which is the ratio of the mass of water to the mass of dry solid, ranges from 6.34% to 25.2% (table 2). the result implies, the soil of the study area dominantly has low water holding capacity as the coarse fraction is dominant grain size. such soils are expected to exhibit lower volume change (swelling and shrinkage) in association with moisture content variation. 3.4.2. grain size analysis the grain size analysis is used to determine the percentage of different grain sizes contained within a soils which in turn is useful for classification and evaluation of the engineering characteristics. the percentages of different particle size for the 30 soil samples collected from 16 test pits are summarized in table 2. the result shows that the predominant size of soil particle in the research area is coarse-grained soils, which have the gravel, sand and fine (silt and clay) fraction ranging from 3.2-32.4%, 62.8-93.1% and 2.926.4%, respectively. 3.4.3. consistency limits and swelling potential the consistency (atterberg) limits of the soils are summarized in table 3. from the results, one can observe that the liquid limit, plastic limit and plasticity index of soil of the study area ranges from 26.06% – 49%, 7.5% – 40.83% and 2.22% – 23%, respectively. according to chen (1975), as he classified swelling potential based on plasticity index, about 86.7% of the soil samples fall in low and about 15.3% soil samples fall in medium swelling potential. the larger the plasticity index, the greater will be the engineering problems associated with using the soil as an engineering material, such as foundation support for residential building and road sub grades (bowles, 1992). the free swell value of the soil of the study area ranges from 0% to 40% (table 3). according to free swell classification of soils, the soil which has free swell value less than 50% is non-expansive, 50-100% is marginal and greater than 100% is expansive (bis is 1498: 1970(r2002)). accordingly, the soils of the study area is considered as low in degree of expansion and expected not to pose significant damage on engineering structures. 3.4.4. ph of the soils the knowledge of chemistry of soil, such as ph, is essential to determine the aggressiveness of the soil to the engineering structure. dissolution reaction is higher at acidic and alkaline ph condition that can deteriorate (corrode) concrete of engineering structure. according to laboratory results (table 3), the ph values of soils of the study area (at 1.5 m) vary from 4.48 (acidic) to 6.7 (weak acidic) indicating their corrosive nature. further chemical test such as electrical conductivity (ec) and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 111 sulphate content shall be conducted to assess the constituents that can cause concrete to deteriorate. 3.4.5. engineering classification of soil engineering classification of soils is the arrangement of soils into different groups and subgroups according to their engineering behavior. its main purpose is for preliminary assessment of the engineering behaviors of soils using simple tests. among the different classification system, unified soil classification system (uscs) is used in this study as it is the popular system for use in all types of engineering problems involving soils (arora, 2003). it considers textures and plasticity and classifies soils into two broad categories: coarse and fine grain. accordingly, the soils of the study area were classified as: sm, sw-sm, sp-sm, sp-sc, sc, sw, and sp (table 4). according to general engineering suitability of the soils (arora; 2003), most of the soils of the study area characterized by negligible to low compressibility, good to excellent shear strength and good to excellent in engineering workability. the results indicate that they are not problematic soils for engineering application with lower swelling-shrinkage potential. table 2: natural moisture content, specific gravity and grain size analysis results sample designation depth (m) nmc (%) sg % grain fraction gravel sand fines (silt & clay) tp-1-1 1.41 18.72 2.14 10 82.4 12.6 tp-1-2 3.00 14.80 2.33 8.8 83.2 8.0 tp-2-1 1.50 6.43 2.50 10 82.6 7.4 tp-2-2 3.00 11.47 2.33 10 82.8 7.2 tp-3-1 1.50 12.75 2.50 18.6 67.4 14 tp-3-2 3.00 15.61 2.12 32.4 63.6 4.0 tp-4-1 1.30 12.07 2.33 16.6 76.8 6.6 tp-4-2 1.70 11.47 2.33 13.6 77.6 8.8 tp-5-1 1.40 11.36 2.00 28.8 62.8 8.4 tp-5-2 3.00 11.64 2.00 20.8 71.2 8.0 tp-6-1 1.20 10.35 2.33 12.2 77.2 10.6 tp-6-2 3.00 11.31 2.33 5.8 89.4 4.8 tp-7-1 1.51 16.72 2.14 12.2 77.2 10.6 tp-7-2 3.00 13.48 2.14 5.8 89.6 4.6 tp-8-1 1.30 12.46 2.54 5.8 89.6 4.6 tp-8-2 3.00 6.34 2.57 24.8 64.0 11.2 tp-9-1 1.35 11.02 2.54 20.68 66.72 12.6 tp-9-2 3.00 18.31 2.55 4.0 90.1 5.9 tp-10-1 1.48 17.1 2.58 13 77.6 9.4 tp-10-2 3.00 25.2 2.61 13.38 74.02 12.6 tp-11-1 1.50 14.82 2.50 7 70.4 22.6 tp-11-2 3.00 22.93 2.14 3.4 70.2 26.4 tp-12-1 1.45 13.36 2.35 6.2 75.2 18.6 tp-12-2 3.00 15.37 2.14 3.2 81.8 15 tp-13-1 1.50 22.32 2.14 3.2 91.2 5.6 tp-13-2 3.00 15.69 2.29 17.6 72 10.4 tp-14-1 1.42 21.03 2.29 12.4 71.8 15.8 tp-14-2 3.00 20.51 2.33 14.2 81 4.8 tp-15 3.2 2.37 4.0 93.1 2.9 tp-16 2.6 2.67 4.9 91.2 3.9 yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 112 table 3: atterberg limits, free swelling and ph results of soils of the study area sample designation liquid limit (%) plastic limit (%) plasticity index (%) free swell (%) ph tp-1-1 26.06 23.81 2.25 10 5.56 tp-1-2 34.44 29.83 4.61 0 tp-2-1 28.59 23.47 5.12 10 5.2 tp-2-2 28.04 20.13 7.91 10 tp-3-1 32.68 28.89 3.79 10 4.48 tp-3-2 27.50 22.22 5.27 20 tp-4-1 31.39 24.24 7.15 20 6.2 tp-4-2 35.00 32.30 2.70 30 tp-5-1 31.75 28.04 3.70 10 6.7 tp-5-2 26.46 21.48 4.97 20 tp-6-1 31.35 27.59 3.76 10 5.62 tp-6-2 28.6 23.21 5.39 30 tp-7-1 45.14 40.83 4.31 0 5.4 tp-7-2 28.05 22.71 5.34 5 tp-8-1 49.05 37.82 11.23 10 6.5 tp-8-2 36.01 33.80 2.22 10 tp-9-1 41.14 31.4 9.74 17 5.3 tp-9-2 34.84 29.04 5.8 19 tp-10-1 34.2 25.8 8.4 28 5.8 tp-10-2 33.64 26.11 7.53 39 tp-11-1 36.94 27.42 9.51 18.2 6 tp-11-2 43.79 29.81 13.98 8.3 tp-12-1 43.98 32.78 11.2 22.7 5.5 tp-12-2 38.41 15.57 22.84 25 tp-13-1 30.37 7.5 22.87 16.7 6.5 tp-13-2 37.24 29.41 7.83 9.1 tp-14-1 41.14 31.4 9.74 8.3 5.5 tp-14-2 42.25 29.41 12.83 9 tp-15 31.35 27.59 3.76 6 tp-16 30.15 26.49 3.66 16 6.4 3.5. engineering geological and geotechnical characterization of rocks the rocks of the study area were classified according to international society of rock mechanics (isrm, 1981). based on the strength (unconfined compressive strength) of intact rock; rock of the study area are classified into three major engineering geological subunits: low strength rock mass units, medium strength rock mass units and high strength rock mass units. in addition, visual description and estimation of their weathering grade and discontinuity surface conditions were conducted. during the time of investigation, the groundwater conditions of all the joints were dry for all outcrops. 3.5.1. low strength rock mass unit the strength of this unit is very low to measure using schmidt hammer. even though it is not the weathering product, similar to engineering soil it can be excavated using simple hand tools. it includes scoria and volcanic ashes. 3.5.1.1. scoria this rock unit covers limited area in the southeastern part of the study area (figure 7) in the form of volcanic cone. its color varies from dark to red color depending on the degree of weathering. texturally it is vesicular/highly porous and fragmented due to explosive mode of eruption. the fragmented grains are not cemented together. the individual grains are characterized by rough surface and sub rounded. yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 113 table 4: classifications of soils of the study area based on unified soil classification (uscs) sample designation percent of particle size ll (%) pi (%) group symbol group name gravel sand fine tp-1-1 5 82.4 12.6 26.06 2.25 sm silty sand tp-1-2 8.8 83.2 8.0 34.44 4.61 sp-sm poorly graded sand with silt tp-2-1 10 82.6 7.4 28.59 5.12 sw-sm well graded sand with silt tp-2-2 10 82.8 7.2 28.04 7.91 sp-sc poorly graded sand with clay tp-3-1 18.6 67.4 14 32.68 3.79 sm silty sand with gravel tp-3-2 32.4 63.6 4.0 27.5 5.27 sp poorly graded sand with gravel tp-4-1 16.6 76.8 6.6 31.39 7.15 sp-sm poorly graded sand with silt and gravel tp-4-2 13.6 77.6 8.8 35.00 2.70 sw-sm well graded sand with silt tp-5-1 28.8 62.8 8.4 31.75 3.70 sp-sm poorly graded sand with silt and gravel tp-5-2 20.8 71.2 8.0 26.46 4.97 sw-sc well graded sand with clay and gravel tp-6-1 12.2 77.2 10.6 31.35 3.76 sp-sm poorly graded sand with silt tp-6-2 5.8 89.4 4.8 28.6 5.39 sw well graded sand tp-7-1 12.2 77.2 10.6 45.14 4.31 sp-sm poorly graded sand with silt tp-7-2 5.8 89.6 4.6 28.05 5.34 sw well graded sand tp-8-1 5.8 81.6 12.6 49.05 11.23 sm silty sand tp-8-2 22.8 64.0 13.2 36.01 2.22 sm silty sand with gravel tp-9-1 20.68 66.72 12.6 41.14 9.74 sm silty sand with gravel tp-9-2 4.0 90.1 5.9 34.84 5.8 sp-sm poorly graded sand with silt tp-10-1 13 77.6 9.4 34.2 8.4 sp-sm poorly graded sand with silt tp-10-2 13.38 74.02 12.6 33.64 7.53 sm silty sand tp-11-1 7 70.4 22.6 42.25 12.83 sm silty sand tp-11-2 3.4 70.2 26.4 43.79 13.97 sm silty sand tp-12-1 6.2 75.2 18.6 37.24 7.83 sm silty sand tp-12-2 3.2 81.8 15 30.37 22.84 sc clayey sand tp-13-1 3.2 91.2 5.6 38.41 22.87 sp-sc poorly graded sand with clay tp-13-2 17.6 72 10.4 43.98 11.2 sp-sm poorly graded sand with silt and gravel tp-14-1 12.4 71.8 15.8 41.14 9.74 sm silty sand tp-14-2 14.2 81 4.8 36.94 9.51 sw well graded sand tp-15 4.0 93.1 2.9 sp poorly graded sand tp-16 4.9 91.2 3.9 30.15 3.66 sp poorly graded sand 3.5.1.2. volcanic ash this rock unit covered large part of the study area (figure 7) and at some places it contains layers of pumice. it is fine to coarse grained in texture and brownish in color. it is loose and unconsolidated deposit, as a result it is easily eroded. as stated in bell (2007), ashes are often highly permeable and frequently prone to sliding. 3.5.2. medium strength rock mass unit this engineering geological subunits include slight to moderately weathered ignimbrite, basalt and rhyolite. 3.5.2.1. moderately weathered ignimbrite medium strength ignimbrite rock unit is found in the northern, western, south-western and north-western part of the study area (figure 7) along the fault scarp. it is light brown and greenish in color. texturally it is yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 114 porphyritic in texture (i.e. clasts and ground mass) and moderately weathered. the strength of the rock material ranges from 25.7 to 58 mpa. three sets of joints (strike nw, n-s and ne) are dominant which are steeply dipping and medium to widely spaced (21 cm to 2 m). the joint surface is both rough and smooth and planar. the aperture is variable and ranges from open to very wide (6 mm to 3 cm). the aperture is partially filled with fine materials and rock fragments. figure 7: multipurpose large scale engineering geological map of the study area (the scale reduced from 1:10000) 3.5.2.2. moderately weathered rhyolite yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 115 medium strength rhyolite rock subunit is found at the south-eastern part of the town around adama industrial park and south-west (boku ridge) (figure 7). it is light brown in color. it is fine grained and moderately weathered. the strength of the rock material varies between 36 to 54.2 mpa. two sets of joints (ne and se) are dominant which are vertical. the joint is medium to widely spaced (20 cm to 82 cm). the joint surface is rough and planar. the aperture is open and partially filled with rock fragments. 3.5.2.3. slightly to moderately weathered basalt the basalt rock unit covers limited area in the western and central part of the town (figure 7). it is light gray to light dark in color, fine grained, vesicular and slightly to moderately weathered. the strength of rock material varies from 33 to 58 mpa. three sets of joints (e-w, sw and ne) are dominant. most of the joints are vertical. the joints are medium to widely spaced (20.5 cm to 1.34 m). the aperture varies from tight to very wide (0.2 mm to 2.1 cm). the joint wall or surface is planar and rough. some joints in fine grained basalt are partially and completely filled with fine soil material. the vesicles of vesicular basalt are filled by secondary materials (quartz/silica). 3.5.3. high strength rock mass unit this engineering geological subunit includes fresh to slightly weathered high strength ignimbrite and rhyolite. 3.5.3.1. slightly weathered ignimbrite high strength ignimbrite rock subunit is found on the faults that bound the town at the east, northeast and southwest direction (figure 7) and it forms steep cliff. the strength of rock material varies from 62.5 to 80.6 mpa. the joints are medium to widely spaced (22 cm to 1.53 m). two sets of joints; (striking nw and se) are dominant. the joint surface is both smooth and rough and planar. the aperture varies from partly open to moderately wide (0.5 mm to 8 mm). the aperture is open and partially filled with fine material. 3.5.3.2. fresh to slightly weathered rhyolite high strength rhyolite rock subunit is mainly found at the south-west and south-east part of the town (figure 7). it is light gray in color. it is fine-grained and fresh to slightly weathered. the strength of the rock material varies between 64 to 79 mpa. three sets of joints (striking nw, ne and se) are dominant which are vertical. the joint is medium to widely spaced (22 cm to 86 cm). the joint surfaces are rough and planar. the aperture is variable and ranges from open to very wide. some joints are filled with fine materials and the other is partly filled with rock fragments. 4. conclusions and recommendations the soils of the study area are dominantly coarse grain with the content of gravel, sand and fine fractions range from 3.2% to 22.8%, 62.8% to 93.1% and 2.9% to 26.4%, respectively. the natural moisture content varies from 6.34% to 25.2%, indicating the water holding capacity of the soils is very low. the liquid limits, plastic limit and plasticity index in percentage range from 26.06% – 49.05%, 7.5% – 40.83%, 2.22% – 22.84%, respectively. according to range of plasticity index, most of the soils (87%) of the study area are characterized as low plastic and low compressible soil. the potential expansion behavior or swelling nature of the soils is also found to be low with free swell value ranges from 0 to 40%. the soils are dominantly sand and silty sand engineering soil type and characterized by good to excellent engineering workability and don’t pose significant damage on engineering structures. however, the acidic nature of the soils can deteriorate (corrode) concrete of engineering structure. the main lithological rock units exposed in the study area are ignimbrite, rhyolite, basalt, scoria and volcanic ashes with pumice. these lithological rock units are classified into three major engineering geological subunits: rocks with low mass strength (which include volcanic ashes with pumice and scoria), rocks with medium mass strength (medium strength ignimbrite, basalt and rhyolite) and rocks with high mass strength (high strength ignimbrite and rhyolite). the study area is exposed to multiple geo-hazards such as flooding, land slide, gully erosion and earthquake. the weathered rock fragments accumulation along the slope of the fault planes especially in the eastern part of the town can result landslide by earthquake occurrence. from the safety point of view, it is, therefore, recommended to avoid settlement and construction in such areas. construction of cheek dams and gabions are recommended to reduce gulley erosion. the design of any engineering structure in the town shall meet all necessary seismic resistant design parameters as the town is located in seismically active zone. yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 116 acknowledgment this paper is part of adama science and technology university’s 10th cycle of research grant. therefore, adama science and technology university, office of vice president for research and technology transfer deserves gratitude for funding this research project. reference arora, k. r. 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(1990). geology, geochronology and rift basin development in the central sector of the main ethiopian rift. geological society of american bulletin, 102: 439 – 458. 44 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper determination of residue levels of ddt and its metabolites in khat and cabbage samples using quechers sample preparation method combined with gc-ms detection challa regassa, teshome tolcha, kefyalew gomoro, negussie megersa  department of chemistry, addis ababa university, p. o. box 1176, addis ababa, ethiopia article info abstract keywords: quechers extraction method gc-ms cabbage khat. a simple and selective extraction technique based on a quick, easy, cheap, effective, rugged and safe (quechers) sample preparation method coupled with gas chromatography-mass spectrometric detection (gc-ms) was developed and applied for simultaneous determination of 1,1,1-trichloro-2,2di(4-chlorophenyl)ethane (p,p'-ddt) and its main metabolites 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (p,p'-dde) and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (p,p'-ddd) in cabbage and khat samples. parameters that primarily affect the extraction efficiency of the analytes were optimized. the significance of the use of cleanup was investigated and its optimum amount was found to be 6 mg psa and 12 mg c18. the optimum values for acetonitrile volume and ph of the sample was found to be 3 ml and 7, respectively. the linearity of the analytical response was acceptable with correlation coefficients of 0.992 or better. the precision associated with the analytical method, expressed as %rsd were lower than 8.6 and 9.1% for the intraday and interday precision, respectively. the limit of detection (lod) and limit of quantification (loq) of the proposed method for cabbage sample were in the range of 2x10-5–4x10-5 mg/kg and 9x10-5–14x10-5 mg/kg, respectively. the lod and loq of the proposed method for khat sample were in the range of 2x10-5–6x10-5 mg/kg and 7x10-5– 19x10-5 mg/kg, respectively. the recoveries of the method were ranging from 97.16 to 107.99 for cabbage and 72.1 to 90.55 for khat sample. the analytical applications of this method indicated the presence of p,p'-dde, p,p'-ddd and p,p'-ddt in both cabbage and khat samples. the amount of p,p'-dde, p,p'-ddd and p,p'-ddt in cabbage were found to be 0.004, 0.01 and 0.01 mg/kg, respectively. the amount of p,p'-dde, p,p'-ddd and p,p'-ddt in khat were found to be 0.01, 0.03 and 0.07 mg/kg, respectively. the results indicate that there should be continuous monitoring of ddt and its metabolites residues in cabbage and khat samples which in turn is helpful to assess the potential risk of the residues to consumers’ health. 1. introduction pesticides are widely applied in agriculture during the production, processing, storage, transport or marketing of foods to control destructive pests such as insects, plant disease, weeds and other living organisms that endanger our food supply and health (beddington, 2010; damalas and eleftherohorinos, 2011). despite their uses, widespread applications of pesticides may  corresponding author, e-mail: negussie.megersa@aau.edu.et https://doi.org/10.20372/ejssdastu:v7.i1.2020.119 affect human health and the environment as a result of residues that remain in environmental and food samples (ogah and coker, 2012). as a result, the contaminations of food items by such hazardous substances are a worldwide public health concern (beena and kathpal, 2009; latif et al., 2011). dichlorodiphenyltrichloroethane (ddt) is an http://www.ejssd.astu.edu/ mailto:negussie.megersa@aau.edu.et https://doi.org/10.20372/ejssdastu:v7.i1.2020.xx challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 45 organochlorine pesticide which had been used and still being used in some countries to combat malaria, typhus and biting flies. organochlorine pesticides such as ddt are known to create certain health problems such as cancer, immune system malfunction, and disruption of hormonal functions for the warm blooded animals including humans (tomatis et al., 1974; colborn et al., 1996; barriada-pereira et al., 2005). ddt is also known to cause disruptions in the antioxidant system and abnormalities in the central nervous system (castillapinedo et al., 2010). the most dangerous property of ddt is its high bioaccumulation and biomagnification potentials (brooks, 1986). ddt residues are found in the environment because of its slow transformation. ddt persists with a half-life of about 10 years and is metabolized mainly in the liver and partly in the kidneys to its most familiar metabolites dichlorodiphenyldichloroethylene (dde) and dichlorodiphenyld-ichloroethane (ddd) in the body (brooks, 1986; boul et al., 1994). ddt and its metabolites are strongly lipophylic and show an affinity to the fat tissue of animals and humans; as a result they are stored in the body’s fatty tissues. a high dde/ddt ratio show old pollution, but low dde/ddt ratio is evidence of recent ddt pollution (lundholm et al., 1997). recently, there has been a growing interest in the detection and quantification of pesticide residues in agricultural produce intended for human consumption (hercegova et al., 2007; abdulhamid et al., 2016). majority of the farmers, in the developing countries like ethiopia, have little or no knowledge about the health and environmental hazards associated with pesticide handling (yalemtsehay mekonnen and tadesse agonafir, 2002). thus, contamination of the environment with pesticides and the pesticides entry into the food chain is unavoidable in these countries (daniel daba et al., 2011; mekonen seblework et al., 2014). as a result, these factors may be causing contaminations of cabbage and khat samples (owusboateng et al., 2013; daniel daba et al., 2011; shemsu ligan and ahmed hussen, 2014). cabbage (brassica oleraceavarcapitata) is a vegetable with high nutritive value and one of the most consumed vegetables in ethiopia. it is used in stews, eaten boiled and raw in salads. pesticides are widely used in fruits and vegetables to control pests and diseases during farming, transportation, and storage because of their susceptibility to insects and disease attacks (kamrin, 1997; zawiya et al., 2007). khat (catha edulis) is an evergreen perennial shrub plant that belongs to the celastracene family. the leaves are chewed by millions of people, mainly in africa and the middle east, for its psychostimulatory effects due to the presence of the phenylalkylamines in the plant (minaleshewa atlabachew et al., 2015). the plant is one of the cash crops and ethiopia is most likely the major grower and exporter and it is the second most important source of foreign exchange earner for the country after coffee (dechasa lemessa, 2001; toennes et al., 2003; ermias dagne et al., 2010). khat leaves used for human consumption often contain contaminants such as pesticide residues. the contamination of khat plants by pesticides may result from the use of pesticides during cultivation or due to environmental contamination (shemsu ligan and ahmed hussen, 2014; tilahun beniam and ahmed hussen, 2014). the levels of p,p'-ddt and p,p'-dde in khat samples, collected from various districts of sidama zone, southern ethiopia, were reported to be in the range of 10.8-19.7 and 3.5-18.6 µg/kg, respectively (shemsu ligan and ahmed hussen, 2014). all the khat samples investigated by these workers contained residues higher than the eu maximum residue limit (mrl) for total ddt (alimentarius, 2011). the finding of the study performed on pesticides residues analysis from the run-off of the fields growing khat around haramaya, one of the known khat producing areas in ethiopia, has indicated contamination of the nearby lake which resulted in severe pollution of the ecosystem. this shows that although ddt is officially banned for agricultural application, contamination of food still occurs which most likely results from illegal use of pesticide obsolete stocks (amera tadesse and asferachew abate, 2008). this necessitates the study of the possible occurrence of ddt and its metabolities in khat and cabbage grown in these areas since several crops are known to accumulate ddt in their edible parts up to critical levels, which may contribute to intake of the contaminants. thus, the monitoring of ddt and its metabolities residues in khat challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 46 and cabbage samples aids the assessment of the potential risks of these products to consumers’ health. the determination of pesticide residues in food samples is a difficult task, because of the complexity of the matrices and the low concentrations at which these compounds are usually present. thus, despite advances in the development of highly efficient analytical instrumentation for their final determination efficient sample preparation remains an important part of obtaining accurate quantitative results for trace level detection and identification which in turn is helpful to protect the environment and consumer health (barr et al., 2002; beyer et al., 2008). the increasing public concern over the potential health hazard associated with exposure to pesticides has led to the strict regulation of maximum residue limits (mrls) of pesticide residues in food commodities. generally, the complex matrix of agricultural products adversely affects analysis precision, and it is necessary to remove the matrix interference by sample pretreatment, such as extraction and clean up steps (zambonin et al., 2004). the method of extracting pesticide residues from food samples and preparing them for analysis is a time consuming, expensive, and labour intensive process. one of the sample preparation techniques employed for selective enrichment and determination of pesticides in fruits, vegetables, grains and herbs samples is the quechers (quick, easy, cheap, effective, rugged and safe) method which was introduced in 2003 (anastassiades et al., 2003). the method is characterized by using a polar solvent, acetonitrile, for extraction of water containing matrices and addition of salts in order to get phase separation (partitioning of the acetonitrile extract from the water in the sample). the sample cleanup is carried out by using dispersive solidphase extraction (d-spe) or adsorbent materials. it is one of the recent approaches utilized for the isolation of pesticide residues from various food matrices (wilkowska et al., 2011). therefore, the aim of this study is to develop a sensitive, versatile and selective multiresidue method for the quantitative determination of ddt and its metabolites in cabbage and khat samples collected from haramaya district of the oromia regional state, ethiopia by extraction with quechers followed by gc-ms detection. 2. material and methods 2.1. chemicals and reagents the analytical standard p,p'-ddd (99% purity), p,p'-dde (99%) and p,p'-ddt (99%) were obtained from the dr. ehrenstorfer (augsburg, germany). hplc grade acetonitrile (acn) was purchased from sigma aldrich (steinheim, germany) and used as extraction solvent. all other chemicals used in this study were of analytical grade reagents. the salts used as salting-out agents including nacl and (nh4)2so4 were from bdh chemicals ltd (poole, england). hydrochloric acid (hcl) was the product of sigma-aldrich (st. louis, mo, usa) and naoh was from bdh chemicals ltd (poole, england). a 0.1 m aqueous solution of each of the hcl and naoh were prepared and used to adjust the ph to the required values. ultrapure water was obtained by purifying with double distiller, a 8000 aquatron water still (bibby scientific, staffordshire, uk) and deionizer (easypure lf, dubuque). then, it was filtered under vacuum through cellulose acetate filter paper (0.45 µm, micro science) before use. the stock standard solution of 100 mg/l, containing each target analyte, was prepared in n-hexane. intermediate standard solution of 10 mg/l was obtained from the stock solution by dilution. both intermediate solutions and other solutions of lower concentrations were prepared by diluting with reagent water. all solutions were stored in a refrigerator at 4 °c when not in use. parameter optimization including the use of cleanup, acetonitrile volume and ph of the sample were performed by spiking cabbage and khat samples with 0.15 mg/kg of a p,p'-dde, p,p'-ddd and 0.3 mg/kg of p,p'-ddt. the following experimental conditions: sample size, 1 g of each sample; extraction solvent, 3 ml of acetonitrile; volume of water added, 5 ml and salt type and amount, 2.2 g (nh4)2so4 and 1 g nacl were used to evaluate the use of cleanup. the cabbage and khat samples were also spiked with a mixture of the analytes at six concentration levels: 0.05, 0.1, 0.2, 0.4, 0.8 and 1.6 mg/kg for p,p'-dde and p,p'ddd, and 0.1, 0.2, 0.4, 0.8, 1.6 and 3.2 mg/kg for p,p'ddt to construct calibration curves. 2.2. sampling sites and sample pretreatment the cabbage and khat samples were collected from farmers' cultivation plots in haramaya district of the oromia regional state, ethiopia. haramaya is located at 9o24'44.89''n latitude and 42o02'01.06''e longitude challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 47 with elevation of 2021.13 m above sea level. both cabbage and khat samples were randomly collected from four plots. the four samples were wrapped in aluminum foil separately and placed into polythene bags and transported to the analytical research laboratory, department of chemistry, addis ababa university for pesticide residue analysis. each sample was chopped into small pieces, air dried under shade, mixed thoroughly to have a representative sample and ground using mortar and pestle. blank samples were obtained from farmer villages; 5 km away from the sampling sites, where pesticides were not used. they were treated exactly in the same way as were done for the contaminated samples. the presence of pesticide residues were also checked by standard addition. it was found that no traces were detected in all the blanks. 2.3. quechers extraction procedure a 1 gm of each finely ground cabbage and khat samples were weighed accurately into 50 ml teflon centrifuge tubes. three milliliters (3 ml) of acetonitrile and 5 ml water at ph 7 were added to dissolve polar compounds in the matrix, and then samples were shaken vigorously for 5 min by shaker to ensure that the solvent interacts well with the entire samples. after that, 2.2 g (nh4)2so4 and 1 g nacl were added to the sample mixture and vortexed immediately for 1 min and then centrifuged at 3000 rpm for 5 min. the acetonitrile extract was collected from the upper layer and transferred to the d-spe tube containing 6 mg psa and 12 mg c18 sorbent for clean-up. the d-spe tube was sealed and vortexed for 1 min, and then centrifuged at 3000 rpm for 5 min. the extract obtained was filtered using a 0.22 μm nylon syringe filter, transferred to an auto-sampler gc vial and 1 µl of the extract was injected to gc-ms for chromatographic analysis. 2.4. gc-ms analysis an agilent 7820a gas chromatograph (gc) equipped with 5977e mass spectrometer, ms, (agilent technologies, usa) with an inert ion source was used to analyze the pesticide residues level. a db-5ms (usa) ultra inert capillary column (30 m x 250 µm and 0.25 µm i.d.) was used for gc separations. helium gas of purity 99.999% was used as carrier gas at a flow rate of 1 ml/min. the instrumental responses obtained were interpreted using mass hunter chemstation software. the gc injection port temperature was kept at 250oc. splitless injection mode was used during the whole analyses. the oven temperature program was set as follows: 130oc for 0 min; increased to 185oc at 25oc/min ramp rate and held at this temperature for 1 min; then increased to 200oc at 9oc/min ramp rate and maintained at this temperature for 1 min; and finally increased to 290oc at 10oc/min ramp rate and held for 1 min. peaks were identified by their retention time and mass spectra after acquisition of the total ion chromatogram. in order to confirm the retention times of all analytes, scan mode was carried over the range m/z 50-550. selective ion monitoring (sim) mode was used for determination of all the analytes. confirmation of the identity of pesticides was made by selecting the most abundant characteristic target ions of each pesticide and two characteristic fragment qualifier ions. the m/z selected for sim mode detection was as follows: p,p'-dde (176.1, 246 and 317.9), p,p'-ddd (165.1, 235 and 237), p,p'-ddt (199, 235 and 246). the instrumental response was reported as peak area and the average peak areas of the triplicate analyses were used for comparison. 2.5. method validation in order to validate the proposed analytical method, linearity, precisions and limits of detection (lod) were evaluated. the linearity of the method was evaluated at six concentration levels 0.05, 0.1, 0.2, 0.4, 0.8 and 1.6 mg/kg for p,p'-dde and p,p'-ddd, and at 0.1, 0.2, 0.4, 0.8, 1.6 and 3.2 mg/kg for p,p'-ddt. each level was extracted under optimum conditions and injected in triplicate starting with the lowest concentration level. then, calibration curves were obtained by considering the peak areas as the instrumental response versus the analyte concentrations. repeatability or intraday precision (at intervals 4 hours within a day) and reproducibility or interday precision (for three consecutive days) of the method was evaluated by spiking blank cabbage and khat samples with 0.15 mg/kg of p,p'-dde and p,p'-ddd; and 0.3 mg/kg of p,p'-ddt. determination of the recoveries of the analytes in both samples were done by comparing the concentration obtained by extracting spiked sample at 0.15 mg/kg of p,p'-dde and p,p'-ddd; and 0.3 mg/kg of p,p'-ddt to the concentration of spiked extract at the challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 48 same level. the limits of detection (lod) and limits of quantification (loq) were calculated based on the minimum analyte concentrations yielding 3 and 10 times the signal to noise (s/n) ratio of the blank, respectively (abera gure et al., 2014). 3. results and discussion 3.1. quechers parameters optimization in order to obtain the optimal quechers conditions, various parameters including the use of cleanup, volume of the extraction solvent (acetonitrile) and sample ph were studied. the significance of the dspe cleanup step was investigated by analyzing the acetonitrile extracts of cabbage and khat samples with application of the d-spe cleanup procedure, utilizing a combination of 6 mg psa and 12 mg c18. c18 is suitable to extract non-polar and medium-polar compounds from the polar samples. psa has a weak anion exchange function and applies to extract polar compounds from the non-polar samples (tesfa bedassa et al., 2015). the experimental results revealed that the use of 6 mg psa for cabbage and 12 mg of c18 for khat removes several co-extracts to the extent that they could not be measured in the extracts. a combination of psa and c18 as clean up was evaluated at 1 mg interval and below the optimum amount the extract is colored (physical observation). it is impossible to inject this colored extract to gc-ms. therefore, a mixture of 6 mg psa and 12 mg of c18 sorbent were used for clean up in the presence of 45 mg anhydrous mgso4 to absorb water for both khat and cabbage samples for further experiments. the effect of the volumes of extracting solvent (acetonitrile) was investigated using different volumes of the extractant, 3-6 ml, with a constant mass of khat samples (figure 1). below 3 ml of acetonitrile, the organic layer formed is not sufficient to collect. as can be seen from figure 1, peak areas of the target analytes decreased as the volume of acetonitrile increased from 3-6 ml. the increase in peak areas with decreasing acetonitrile volume may be attributed to the preconcentration of the target analytes (melo et al., 2013). but, further reduction of the volume of the acetonitrile below 3 ml was found to be inconvenient since the volume of the extract collected was too small for the subsequent d-spe clean up procedure. therefore, 3 ml acetonitrile was chosen as the optimum volume for further studies. 3.0 3.5 4.0 4.5 5.0 5.5 6.0 100000 105000 110000 115000 120000 125000 130000 135000 140000 145000 150000 155000 160000 165000 170000 175000 180000 p e a k a r e a volume of acn (ml) p,p'-dde p,p'-ddd p,p'-ddt figure 1: effect of volume of acetonitrile. experimental conditions: sample size, 1 g; extraction solvent, acetonitrile; volume of water added, 5 ml; amount of salts added, 2.2 g (nh4)2so4 and 1 g nacl; spiking level, 0.15 mg/kg for p,p'-dde, p,p'ddd and 0.3 mg/kg for p,p'-ddt. the ph of the solution is also one of the important parameters in this study. the extraction efficiency of a weak organic base or acid depends on the ph value of the sample solution (razmara et al., 2011). the ph was varied in the range of 5-9 using either 0.1 m hcl or 0.10 m naoh solution. the experimental results demonstrated that the signals the analytes increased by increasing the ph up to 7 and slightly decreased with further increase in ph. the results are presented in figure 2. based on the above results, the ph value of 7 was selected for subsequent studies. 3.2. analytical method validation the performance of the proposed quechers extraction technique combined with gc-ms was evaluated utilizing matrix-matched calibration curves in order to compensate for the matrix effects. the coefficients of determinations (r2) of the calibration curves obtained from the peak areas as the instrumental response versus the analyte concentrations were 0.992 or better indicating a good linearity of the analytical method over the concentration range studied. the limits of detection (lod) and limits of quantification (loq) ranged from 2x10-5–6x10-5 mg/kg and 7x10-5–19x10-5 mg/kg, respectively. the amount of p,p'-dde, p,p'ddd and p,p'-ddt in cabbage was found at challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 49 concentration level of 0.004, 0.01 and 0.01 mg/kg, respectively. furthermore, the amount of p,p'-dde, p,p'-ddd and p,p'-ddt in khat was found to be 0.01, 0.03 and 0.07 mg/kg, respectively. the amount of all compounds was below the maximum residue level set by european commission for these pesticides (0.2 mg/kg) in both samples (regulation (ec) no. 398/2005; regulation (ec) no. 149/2008). the performance characteristics of the proposed method in both samples are given in table 1. the precision of the method was also determined by the repeatability (intraday precision) and reproducibility (interday precision) studies of the method and expressed as the relative standard deviation (rsd). repeatability (at intervals of 4 hours within the same day) and reproducibility (for three consecutive days) of the method was evaluated by spiking blank cabbage and khat samples with 0.15 mg/kg of p,p'-dde and p,p'ddd; and 0.3 mg/kg of p,p'-ddt. determination of the recoveries of the analytes in both samples were carried out by comparing the concentration obtained by extracting spiked sample at 0.15 mg/kg of p,p'-dde and p,p'-ddd; and 0.3 mg/kg of p,p'-ddt to the concentration of spiked extract at the same level. the results were given in table 2. the results of the recovery studies demonstrated that the method has satisfactory recovery, precision and sensitivity for pesticide analysis in the samples under study. the chromatogram of unspiked and spiked cabbage and khat samples are given in figure 3. 5 6 7 8 9 0 100000 200000 300000 400000 500000 600000 700000 800000 900000 1000000 p e a k a r e a ph p,p'-dde p,p'-ddd p,p'-ddt figure 2: effect of ph. experimental conditions: sample size, 1 g; extraction solvent, 3 ml acetonitrile; volume of water added, 5 ml; amount of salts added 2.2 g (nh4)2so4 and 1 g nacl; spiking level,0.15 mg/kg for p,p'dde, p,p'ddd and 0.3 mg/kg for p,p'-ddt. table 1: statistical and performance characteristics of the proposed method analyte cabbage khat recovery repeatability reproducibility recovery repeatability reproducibility p,p'-dde 99.42 6.63 7.40 72.17 5.74 8.29 p,p'-ddd 107.99 5.88 5.26 82.64 8.58 5.11 p,p'-ddt 97.16 8.22 7.89 90.55 7.35 9.01 challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 50 table 2: recovery (%) and precision (%rsd) of the proposed method for the spiked cabbage and khat samples figure 3: representative chromatograms for unspiked (a) and spiked (b) cabbage; and unspiked (c) and spiked (d) khat samples; peaks: 1, p,p'-dde; 2, p,p'-ddd; 3, p,p'-ddt. spiking level, 0.15 mg/kg for p,p'-dde, p,p’ddd and 0.3 mg/kg for p,p'-ddt. cabbage khat analyte linear range (mg/kg) r2 lod (10–3 mg/kg) loq (10–3 mg/kg) regression equation amount found (mg/kg) r2 lod (10–3 mg/kg) loq (10–3 mg/kg) regression equation amount found (mg/kg) ,p'-dde 0.05–1.60 0.998 0.03 0.09 y = 89849x – 36725 0.004 0.995 0.02 0.07 y = 2e+06x – 11817 0.01 p,p'-ddd 0.05–1.60 0.996 0.04 0.14 y = 61955x – 15518 0.01 0.994 0.03 0.1 y = 2e+06x – 13021 0.03 p,p'-ddt 0.1–3.2 0.993 0.04 0.13 y = 20095x – 7425 0.01 0.992 0.06 0.2 y = 31974x – 49806 0.07 challa regassa et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 51 table 3: comparison of the proposed quechers method with other methods method linear range (mg/l) lod loq (mg/kg) recovery (%) volume of organic solvent (acn) used for extraction, ml references spe-gc 0.002–0.3 0.002–0.004 mg/l 72.4–112.9 zhou et al.; 2013 quechers-gc-ms 0.03–0.36 0.02–0.1 80–115 10 nguyen et al.; 2008 quechers-gc-ms 0.002–1.0 0.001–0.13 70–120 10 cies´lik et al.; 2011 quechers-gc-ms 0.05–3.2 2x10–5–6x10–5 mg/kg 7x10–5–19x10–5 72.1–107.99 3 this study 3.3. comparison of the proposed method with other reported methods table 3 shows comparison of the proposed quechers method with other methods reported so far. the values in the table indicate that the method proposed by our group uses smaller volume of acetonitrile for extraction than the other methods indicating its less deleterious effect on the analyst as well as the environment. the values in table 3 also show that the proposed method has comparable lod, loq and recovery with other reported methods. thus, the proposed method can be used for efficient and selective extraction of the selected pesticides in cabbage and khat sample matrices. 4. conclusion sample preparation is always the major bottleneck in any analytical procedure for the determination of pesticide residues in food products. the quechers multiresidue procedure simplifies and reduces the time taken to complete the extraction and clean-up processes. analytical methods based on a fast gc-ms methodology were developed and validated for determination of ddt and its metabolites in cabbage and khat samples using quechers sample preparation method. the method provided wide linear range, good reproducibility and repeatability over the studied concentration ranges for both cabbage and khat samples. the method also offered low lod and loq for all pesticides under study which demonstrate its usefulness for the determination of the analytes in the samples. the developed method was successfully applied to cabbage and khat samples. the results obtained indicates that the cabbage sample was found to contain p,p'-dde, p,p'-ddd and p,p'-ddt at concentration level of 0.004, 0.01 and 0.01 mg/kg, respectively. the p,p'-dde, p,p'-ddd and p,p'-ddt were also found in khat sample at concentration level of 0.01, 0.03 and 0.07 mg/kg, respectively. the amounts of pesticides detected in both cabbage and khat samples were below the eu maximum residue limits. even though the use of ddt was banned in ethiopia for agriculture purposes, detectable levels are still being observed. the results of the study necessitate the need for awareness creation of the community and continuous monitoring of such pesticides residues in cabbage and khat samples. acknowledgment the authors would like to thank addis ababa university, department of chemistry for the laboratory facilities. this work was financially supported by a thematic research entitled “biodiversity, insect-plant interaction, environmental degradation nexus: towards a sustainable development, climate change mitigation and adaptation in eastern and southern ethiopia”. we are also highly thankful to the international science program (isp) for financial support for the purchase of the standards, mobile phase solvents and chemicals through the project (eth: 04). reference abera gure, lara, f. j., garcia-campana, m., negussie megersa, olmo-iruela, m. 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(2013). solid phase extraction with silicon dioxide microsphere adsorbents in combination with gas chromatography-electron capture detection for the determination of ddt and its metabolites in water samples. journal of environmental science and health, part b, 48(3): 191–197. 115 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 effects of foreign direct investment on socio-economic conditions of local community: the case of dangote cement factory in ethiopia abdisa olkeba jima bule hora university, college of social sciences and humanities, department of civics and ethical studies, p.o. box 144, bule hora, ethiopia. e-mail: olkebabdisa@gmail.com , tel: +251930818102 abstract albeit foreign direct investment (fdi) plays a pivotal role to boost the socio-economic development of one country, there is debate among scholars on whether fdi has positive or negative effects on the local communities. the main objective of this research is to describe the socio-economic effects of fdi on the local community in dangote cement factory in ethiopia focusing on two themes—labors and landholders. the study used a mixed approach—both qualitative and quantitative methods to conduct this research. further, descriptive case study research design was used for detail description of the factory on the local community. moreover, the sample of 190 participants was selected from landholders and labors by using systematic random sampling technique. the finding of this study revealed that fdi has both positive and negative effects on local labors. the positive effects are a creation of job opportunity; an increment of real wage; transfer of knowledge and technology. in contrast, the negative effects are wage difference between skilled labors, and absence of standardized rules and regulations to employ local labors. on the other hands, fdi has negative effects on landholders—an inadequacy of compensation; absence of enough precondition to resettle the landholders; expropriation of landholders from their lands; loss of diversified mode of income and become dependent on only paid compensation; and addiction of youths to chat and alcohol. the researcher concluded that although fdi, dangote cement factory, has both positive and negative effects on labors, it has negative effects on landholders. the researcher recommended that the landholders should be organized into a small and micro-enterprise and invest their capital on investment which can regenerate their income and open job opportunity for themselves rather than use the money alone. the researcher further recommended that labors should be employed only by dangote cement factory directly to avoid wage difference among skilled labors and its agency should be cleared from the factory. keywords: fdi, landholders, local community, economic effect, social effect 1. introduction foreign direct investment (fdi hereafter) is not a recent phenomenon albeit it has been expanded massively with the expansion of globalization. a prominent feature of the global economic landscape in the past few decades has been significantly increased in the international flow of fdi. the movement of fdi across the world has significantly mailto:olkebabdisa@gmail.com abdisa olkeba ejssd, v 5 (2), 2018 116 © adama science & technology university https://ejssd.astu.edu.et increased from 54 billion usd in 1980 to 1.7 trillion usd in 2015 (girum abebe, et al., 2016). due to the merits relate to fdi, developing countries have liberalized their mode of investment to attract fdi. the ambition of developing countries is to boost their economic growth in particular and achieve development in general. fdi benefits host countries in terms of technology spillovers, human capital formation support, enhancement of a competitive business environment, a contribution to international trade integration and improvement of enterprise development and social conditions (kurtishi-kastrati, 2013). on the other hands, it is presumed that fdi has often been accused of taking unfair advantage of low wages and weak labor standards in developing countries. further, fdis also have been accused of violating human and labor rights in countries where governments fail to enforce such rights effectively (oecd, 2008). in 2013, 778 usd billion of the total global fdi flow went to developing countries. africa saw a 4+ percent increase in fdi inflow although developing asian countries continued to be the region with the highest fdi inflow. in east africa, fdi increased by 15 percent to 6.2 billion usd because of rising flows to ethiopia and kenya (selamawit berhe, 2016). fdi introduced into ethiopia during emperor haile selassie at the mid of 20th century. to attract and benefit foreign investors, new policy was designed and the following incentives were included in the new policy: tax exemption, remittance of foreign exchange, import and export duty reliefs, tax exemption on dividends and the provision of finance through the ethiopian investment corporation and the development bank of ethiopia (wubne mulates, 1991). the derg government invited the foreigners in economy albeit failed to attract more since joint venture and misguided national policy measures were taken and the economic system of derg government was socialism. further, proclamation no. 76/1975 limits the private investor to 500,000 birr and advised ethiopians to invest in enterprises larger than cottage industries (teshome adugna, 2010). since the early 1990s, ethiopia has taken significant steps towards liberalization of the economy and private investment (selamawit berhe, 2015). hence, ethiopian privatization agency (epa) was established in 1994 to liberalize the economy and encourage private sectors in the economy (tadesse demissie, 2011). besides, investment proclamations such as no. 84/2003 and no. 146/2008 reforms were made to improve and widen the degree of privatization and attract fdi more (teshome adugna, 2010). indeed, the country sees fdi as an important source of capital to fill the resource gap between domestic investment and saving which remains wide due to low levels of income and domestic saving (selamawit berhe, 2015). by the same token, investment guarantees and protection which encourage foreign investors were abdisa olkeba ejssd, v 5 (2), 2018 117 © adama science & technology university https://ejssd.astu.edu.et launched by the ethiopian government to attract foreign investor currently (ethiopian investment commission, 2014). currently, the major sources of fdi into ethiopia are from china, india, sudan, germany, italy, turkey, saudi arabia, yemen, uk, israel, canada and usa (amanuel mekonnen, 2014). though the asian states—china, turkey, and india—play a dominant role in ethiopian manufacturing sectors (unctad, 2014), currently the african billionaire, aliko dangote, has opened cement factory in 2013 in ethiopia, oromia region, west shewa zone, adea berga woreda, mugher district, 87km away from capital city, addis ababa which has entered into full production on june 2015 with 2.5 mta production capacity (ethiopian investment commission, 2014). dangote cement has been able to expand its cement production business across several countries, which completed building cement production in some countries and in the process of building in some countries. these countries are cameroon, ethiopia, republic of congo, liberia, senegal, south africa, tanzania, kenya, zambia, ivory coast, and ghana. the company has the intention to build in zimbabwe, perhaps in 2019, with 1.5 mta production capacity (akinyoade and uche, 2016). little is known about the local effects of fdi (girum abebe et al., 2016). consequently, this research is aimed to address this gap—whether fdi has positive or negative effects on local communities. further, currently, ethiopia is becoming major fdi inflow destinations from least developing countries in africa” (biruhe eshete & thomas gebre, 2012). hence, the researcher is eager to describe the effect of fdi on socio-economic conditions of the local community due to dangote cement factory in ethiopia. these are reasons that initiated the researcher to conduct the research around this area. generally, this research is designed to describe the effects of fdi on socioeconomic conditions of local communities in general and on labors and landholders in particular in dangote cement factory in ethiopia. 2. methodology of the research to conduct this research, the researcher employed a mixed approach: both qualitative and quantitative methods. further, descriptive case study research design was used for detail description of the factory on the local community. the qualitative method was applied to gather information through semi-structured interview and focus group discussion from adea berga woreda land and environmental protection bureau, and investment bureau administrators; manager and directors of human resources of dangote cement factory; and local elders (“abbaa gadaa” and locally respected and well known elders) who were selected purposively to elicit their views on the effect of fdi, dangote cement factory, on socio-economic conditions of local communities. abdisa olkeba ejssd, v 5 (2), 2018 118 © adama science & technology university https://ejssd.astu.edu.et furthermore, a quantitative method was also used to describe income of labor, to know the total number of labor in the factory, to describe the wage differences of labor in the factory, and to examine the adequacy of paid compensation and income of landholders by using the simple statistical method, frequency distribution. the target populations of this study are labors and landholders. due to the heterogeneous population of participants, study participants were classified into two clusters: cluster one consists of labors participants whereas cluster two consists of landholders. the sample size of the two clusters was determined through systematic random sample technique by using yemene (1967) formula i.e., n = 𝑁 1+𝑁(𝑒)2 where: n = total number of a target population, n = sample size and e = level of precision = 0.1. according to dangote cement factory internal report, 1662 labors are working in the factory, and according to adea berga woreda land and environmental protection bureau, 2370 landholders were displaced from their lands. accordingly, the sample size of labors is: n = 1662 1+1662(0.1)2 = 94 participants, and sample size of landholders is: n = 2370 1+2370(0.1)2 = 96 participants. hence, the total number of 190 participants was selected from labors cluster and landholders cluster. finally, the collected data were analyzed by the multi-stage method, qualitative and quantitative, data analysis. the qualitative data were analyzed by the content and theme analyzing method whereas the quantitative data were analyzed by spss version 20. then, information obtained from the quantitative method was triangulated with information obtained through qualitative methods. 3. findings and discussion 3.1. effects of fdi on local labors the fdi, dangote cement factory, has two dimension effects: positive effect and negative effect on local labor. 3.1.1. positive effects of fdi on local labor fdi has positive effects on local labors in terms of job creation, increments of productivity; raises of wages and transfer of knowledge, skills, experience, and technology. job opportunity dangote cement factory has created a job opportunity for local labors directly and indirectly. directly, the factory employed both casual and permanent local labors who are working in the factory currently. indirectly, many local labors were organized and are supplying raw materials for the factory. accordingly, more than 250 labors were organized and entered into work in east shewa zone to mine the raw materials which are necessary for the factory. as indicated in table 1, below, most of the labors who are working in the dangote cement factory are local labors. the total percentage of local labors in the abdisa olkeba ejssd, v 5 (2), 2018 119 © adama science & technology university https://ejssd.astu.edu.et factory is 98.02% (the sum of permanent and casual labors). out of 1662 total labors, the local labors account of 1629. this shows that the dangote cement factory (fdi) plays a vital role in job creation for local labors. table 1. total number of employed labor in the factory (source: dangote cement factory internal report, 2017) no. type of labor quantity percentage (%) 1 permanent 1597 96.09 2 casual 32 1.93% 3 expatriate 33 1.99% total 1662 100% raises of real wage further, when we compare a domestic investment with fdi, the wage of labors that the fdi pays for its labors is higher than the domestic investment. the finding of this research revealed that dangote cement factory pays 8000.00 etb monthly wage for the beginner labors who have first degree with no experience. this means the experienced labors are paid more than 8000.00 etb according to their experience. as indicated in table 2, the mean monthly income of labors of dangote cement factory is 7819.78 etb. further, the median monthly income of the labors is 7,500 etb. this indicates that both the mean and median monthly income of labors of dangote cement factory is nearest to 8000 etb which is high and hence, the factory affords the real wage to its labors. hale and xu (2016) asserted that fdi leads to higher real wage. by the same token, the finding of this research revealed that fdi, dangote cement factory, increases the real wage of local labors who are working in the factory currently. table 2. labor’s income of the dangote cement factory (etb) transfers of knowledge, technology, skills, and experience in addition to job opportunities and raises of real wage, the fdi also plays a pivotal role in transfers of knowledge, technology, skills, and experience. in dangote cement factory, there are a number of foreigners who came from china, india, and nigeria and working in the factory albeit the majority of labors in the factory are local labors. alongside with those foreigners, there are many mean 7819.78 median 7500.00 mode 3000.00 std. deviation 4758.18 abdisa olkeba ejssd, v 5 (2), 2018 120 © adama science & technology university https://ejssd.astu.edu.et local labors who are working in one office. while they are working in one office, they grasped knowledge, experience, know-how, and skills from those foreigners. initially, the technical operation was dominated by foreigners in the factory. but gradually, local labors began to replace the foreigner in some operations. the labors focus group discussant recognized that “unless we learned and shared experience from the foreigners, we could not survive in this factory”. moreover, local labors who grasped the foreigner knowledge and experience, and developed their skills are working in others dangote cement factory, which exist outside of ethiopia. consequently, foreigners who came from different countries and have different experiences and skills are transferring their skills, know-how, and expertise to local labors. increment of productivity productivity is one of the factors that enable one factory to produce goods at higher rates. in dangote cement factory, many local labors learned the new system of production, the new technology, and new system of operation and hence, they would increase their skills, know-how, and experience since the diffusion of technology and ideas are spillover from more technologically advanced countries to developing countries like our country, ethiopia. hence, the spillover of the technology and ideas increased the skills of local labors, broaden the root of their knowledge and leads them to higher productivity. gorgen et al. (2009) described that fdi increases in working standard if foreign investors employ local labor. besides, the finding of this research also indicated that fdi increases the productivity of local labors since they shared knowledge, experience, skills, and know-how from foreigners. labor focus group discussants explained that “by using the knowledge, skills, and experience we have acquired from the foreigners in this factory, now we become more productive.” generally, dangote cement factory has created job opportunity for a number of local labors, raised the real wage of local labors, introduced and transferred new technology, skills, experience, and know-how which help local labors to increase their productive capacity and ability, and these all play a significant role in changing the life of local labors and make them competent both at regional and international levels. 3.1.2. negative effects of fdi on local labor the finding of this research also showed the negative effects of fdi on local labors. according to the collected data from the participants, the negative effects of fdi on local labors are wage difference among skilled labors; absence of standardized rules and regulation to hire local labors; and exclusion of local labors. wage difference among skilled labors abdisa olkeba ejssd, v 5 (2), 2018 121 © adama science & technology university https://ejssd.astu.edu.et albeit dangote cement factory has created job opportunity for many local labors and raised their real wage, it, according to the finding of this research, created wage difference between skilled labors who were employed by the dangote and labors who were employed by its agency. in the factory, most of the labors were hired by agency though some are hired by dangote directly. albeit the labors who were employed by agency and dangote have the same qualification, experience and work the same hour, the agency is paying a lesser wage for the labors who were recruited by it. hence, there are two payrolls which are maintained by the factory: one for the direct recruits and other for agency recruits. similarly, the quantitative finding of this study revealed that there is more than 7000 etb monthly mean wage difference and more than 6000 etb monthly median wage difference between labors who were employed by dangote and labors who were employed by the agency. table 3. wage difference between skilled labors (etb) stat. description dangote’s labor agency’s labor wage difference mean 15116.67 7803.20 7313.47 median 14255.00 8000.00 6255.00 mode 13000.00 8000.00 5000.00 std. deviation 3593.78 1048.73 2545.05 as indicated in table 3, above, there is 7313.47 etb mean wage difference and 6255.00 etb median wage difference between labors who were employed by dangote and labors who were employed by its agency nevertheless, their qualification and experience are the same. but, note that the above wage comparison did not include the wage of top managers and expatriates because they were unwilling to participate in the research. without including the wage of top managerial personnel and expatriates, which could be greater than the maximum wage expressed in table 3, there is wide wage difference among the local labors. fdi increase wage inequality due to an increase in the skill premium which is the difference between the wages of the skilled and unskilled labor force” (hale & xu, 2016). unlike the hale & xu (2016) finding, the result of this research indicated that there is wage difference between skilled labors because the labors who were employed by an agency are subjected to pay commission for an agency which is deducted from their monthly income. the absence of standardized rules and regulations rules and regulations are the principles that govern certain conduct, abdisa olkeba ejssd, v 5 (2), 2018 122 © adama science & technology university https://ejssd.astu.edu.et work, and activities. they play a pivotal role to work diligently and raise productivity. if rules and regulations are violated, there will be the prescription of punishment by respective body and/or organization otherwise it will cause dispute and conflict. the local community had the reverse attitude toward dangote cement factory on employment. they believed that those who were removed from their lands and their children should be employed in the factory without any requirement. in fact, this is a dream and impossible since every work requires respective experience and qualification. on the other hand, all children of those local communities could not get the job in the factory albeit they wish that all of their children had employed in the factory. furthermore, they did not identify the qualification and specialization fields of their children. for example, the one who graduated in sports science could not be employed in the dangote cement factory although local communities assumed it. besides, the absence of standardized rule and regulation on what numbers of local communities’ labor have to get a job in the factory is making the things more difficult and worse. to avoid such ambivalent ideas, there should be standardized rule and regulation which express about to what extent, qualification and degree the local labors are employed in the dangote cement factory. exclusion of local labors local labors are always eager to be employed in the dangote cement factory since they believed that the owner of the factory is a foreigner and hence, pays much more than domestic factory; their family left their lands for the factory, and they believed that no one who comes from other areas could employ before them. contrary to this, many local labors were excluded by the agency. people who work in the agency came from other areas—from tigray regional state nevertheless, the factory was built in oromia regional state. they did not understand the local norms, values, taboos, tradition, culture, and language. initially, most of the local labors were excluded even though rhetoric is there now after the confrontation and revolt of local communities. furthermore, the manager of the factory is a foreigner— indian. like agency, he lacks sufficient awareness on the ways of life, values, language, norms, custom, belief, culture and taboos of the local community and ‘thus, unable to reconcile the local labors perception and the interest of the factory. these all contributed to the exclusion of local labor and gradually cause tension and then conflict in dangote cement factory. 3.2. effect of fdi on landholders even though dangote cement factory effects local labors both positively and negatively, it affects the landholders negatively because of lowness of paid compensation, food insecurity of landholders; low level of saving habit of the landholders; absence of continuous abdisa olkeba ejssd, v 5 (2), 2018 123 © adama science & technology university https://ejssd.astu.edu.et training and awareness on saving habit; absence of preconditions to resettle them; and joblessness of landholders and their children. the details of the collected data are discussed below by focusing on compensation, income, and livelihood, rights to land, social conflict and culture. 3.2.1. compensation method the interviewed administrators of land and environmental protection, and investment bureaus of adea berga woreda explained that the paid compensation for landholders was varied based on the farmlands, grazing lands, irrigable lands, and non-irrigable lands. the period of compensation was calculated for ten years though the lands will not be returned back to the owners of land after ten years. and hence, the paid compensation is inadequate. the data gathered from landholders through fgd, and from woreda land and environmental protection through interview disclosed that the compensation was paid for all landholders in cash. the compensation paid for farmland is different from grazing land. for instance, around 350,000etb was paid per hectare for farmland. on the other hand, for grazing land, around 300,000etb was paid per hectare. further, the method of payment was based on the market prices of crops during the compensation was paid and hence, it did not take into account the future inflation of the market. at that time, the payment for farmland was based on the costs of grain per kilogram of that time i.e. if 100kg teff =1600 etb, the total payment was based on the capacity of the land it produces in kilogram per year by taking the average of five years. if one hectare has the capacity to produce 2000kgs (40 sacks) per year for five years averagely, the total payment was (2000kgs × 1600 birr × 10 years) /100kgs=320,000etb per ha. by the same token, the grazing land is also calculated by the same process— based on the cost of the grass during the compensation was paid. but now the cost of 100kgs of teff is nearly 2500 birr. it might be doubled in the coming year since the rate of inflation is high in ethiopia when compared with the costs of crops or teff when they evicted from their lands. furthermore, the landholder fgd participants explained that they could plow their land for more than ten years or throughout their life, but the compensation was paid by estimation of only ten years. as indicated in table 4, 16.67% of participants scored above 3 on the measure of the adequacy of compensation. on the other hands, 78.13% of participants scored below 3 on the measure of the adequacy of compensation. this indicates that the majority of participants agreed that the paid compensation is inadequate. abdisa olkeba ejssd, v 5 (2), 2018 124 © adama science & technology university https://ejssd.astu.edu.et table 4. adequacy of paid compensation compensation status frequency percentage (%) adequate (>3) 16 16.67 neutral (=3) 5 5.21 inadequate (<3) 75 78.13 total 96 100% 3.2.2. income and livelihood the landholders had diversified mode of income, before they were evicted from their land by fdi, dangote cement factory. majority of them used to cultivate crops, herd animals like cattle, sheep, goats, horses, and donkeys. they could sale them during the time of emergency. moreover, they used to produce fruits and vegetables by using irrigation since some of their lands were nearest to the river. contrary to this, the current income of the farmers is depending on only one time paid compensation. those who are educated and have experience in saving money, bought houses and generate income by renting them. some became traders. others bought sino trucks and were generating the income from them. but, most of them who left the lands have no experience to save the cash. further, no training was given for the landholders on how to use the money. now, they buy all things from the market and hence, the paid compensation is incapable of to feed their families. concerning their livelihood, the entire landholder focus group discussants remarked: “initially, we assumed as all of us will be an investor by using the paid compensation. then we received compensation and began to use it. after one year, many of us finished the money. before we left our lands and moved to the town, we had plowed lands we owned and could get more than 100 quintals per year. that was sufficient to feed our family even up to two years. besides, we used to fatten cattle and herd dairy cattle and could get more than 55,000 birr per year. furthermore, we and members of our families were busy with the production of potatoes, onion, garlic, cabbages, and maize. as a result, all of us had our own work. we used to live a good life. but now albeit we wished to live a better life than former, we are left as a dreamer. we wish if we reowned our land and lived the former life. the government should give us another land. wherever it is, we shall go and ready to plow it” (landholder fgd participants). abdisa olkeba ejssd, v 5 (2), 2018 125 © adama science & technology university https://ejssd.astu.edu.et by the same token, the quantitative finding of this research showed that the former income and livelihood of landholders was better than the current one. table 5. current betterment of income and livelihood of landholders income& livelihood comparison frequency percentage (%) better (>3) 11 11.46 neutral (=3) 10 10.42 not better (<3) 75 78.13 total 96 100 as indicated in table 5, above, 11.46% of participants scored above 3 on current betterment of income and livelihood of landholders. on the other hands 78.13% of participants scored below 3 on current betterment of income and livelihood of landholders. this indicates that the majority of participants agreed that current income and livelihood of landholders is not better. as a result, the former income and livelihood of landholders is better than the current. diallo and mushinzimana (2009) posited that fdi has negative impacts on local landholders since the situation of displaced farmers is often worse than before with inadequate compensation for their loss of land. by the same token, the finding of this research displayed that the former livelihood of landholders are better than their current livelihood. 3.2.3. right to land the fdre constitution article 40(4) stated that ethiopian peasants have the right to obtain land without payment and the protection against eviction from their possession. further, the federal rural land administration and land use proclamation no. 456/2005 assured the right of landholders. specifically, article 5 sub article 1 (a) of this proclamation entitled that any citizen of the country who is 18 years of age or above and wants to engage in agriculture for living shall have the right to use rural land. besides, article 7 (1) also assures about the duration of rural land right use by entitling that the rural land use right of peasant farmers, semi-pastoralists and pastoralists shall have no time limit. this article clearly stated that peasants can use their land and inherit to his/her successors forever. moreover, the oromia regional state land use and administration, the amended proclamation no. 130/2007 article 5 (1) grants the peasants’ right as follow: any peasant or pastoralist, or semi pastoralists who have the right to use rural land shall have the right to use and lease on his holdings, transfer it to his family member and dispose property produced there on, and to sell, exchange abdisa olkeba ejssd, v 5 (2), 2018 126 © adama science & technology university https://ejssd.astu.edu.et and transfer the same without any time bound. on the other hands, both proclamations: federal and oromia regional state handover the abovementioned rights of landholders by the name of investment and public use. the entire fgd participants explained: “we had identification card which certifies us to own land and use it albeit it did not guarantee us up to the end. we inherited our lands from our families. we supposed that as we inherited the land from our families, our children will also inherit it. we further supposed that we had full right on our lands. but after the dangote cement factory had come and had evicted us from our lands, we lost the right to use our lands although it is assured and granted by the constitution. following this, we strongly protested and tried to fight for our rights, but unable since the government took a hostile policy stance” (landholder fgd participants). an interview with adea berga woreda land and environmental protection administrator showed that the dangote cement factory displaced more than 2370 landholders from their lands without adequate compensation. 3.2.4. social conflict social conflict can be defined from different angles. but for the purpose of this research, social conflict is the conflict that was struck by the local community against fdi on their benefit. social conflict has emerged with the coming of dangote cement factory which was caused because of inadequacy of compensation; deterioration of livelihood of landholders; lowness of current income; expropriation of landholder from their lands; exclusion of local labor (especially labors whose family were evicted from lands); wage difference between skilled labors; existence of corruption during employing labor which was caused by agency; high commission of agency; and lowness and absence of any precondition to resettle the landholders. the collected data from different bureaus and participants showed that due to the social conflict, many trucks, the property of the dangote cement factory, were burnt and broken down. the administrator of woreda investment bureau noticed, “lack of uniformity in implementing policy, programs, and strategies by different organs which found at different levels; leading of investment bureaus by politicians, and politicizing the questions of local community aggravated the conflicts more” (interview with woreda investment bureau administrator). 3.2.5. cultures sociologists defined that culture is a collective of shared values, customs, norms, tradition, knowledge, and language that is practiced among the community for a long period of time. the collected data from landholders through interview and fgd showed that fdi has negative effects on indigenous culture. further, the landholders had their own culture in the place where they used to abdisa olkeba ejssd, v 5 (2), 2018 127 © adama science & technology university https://ejssd.astu.edu.et live rural area. they had a common language -‘afaan oromoo’, common values, the traditional way of resolving conflict through ‘jaarsummaa’ the process of solving disagreement and dispute by local elders informally without going to the court, common wedding styles, common eating style and wearing style. their children used to wear beautiful indigenous clothes. but after they had come into the town, their children began to follow the cultures of western. they totally lost the rural life and tried to act as urban dwellers by imitating the act of western. further, while they were living in rural area, their children used to stand up when their father and elders entered into the house to welcome them and show respect. but now, they completely lost that good culture. moreover, they used to eat together there, especially, during holidays. no one ate alone. even those who conflicted before reconciled at that time. they also used to work together plowed the land together, mowed together, harvested together, cultivated together, and used to build together. generally, the result of this research showed that local community lost their identity; began to learn new language by relinquishing their mother tongue to adapt into new environment; lost the traditional way of celebrating wedding styles and expressing condolence, and obliged to learn the new culture in the new environment; access to media in urban area pursued the children of local community being attracted by western cultural ways of life and began to neglect indigenous culture such as eating style, respect, hospitality, wearing style, norms, values and tradition; youths are addicted to chat and alcohol; females began to participate in prostitution activities to generate incomes, and this opened the way for widespread of hiv/aids. 4. conclusion foreign direct investment (fdi) plays a significant role in enhancing economic growth and boost development. albeit the role of fdi in economic development is high in developing countries, it could not totally escape from criticism on its negative sides in host countries. having this as the departure, this research, which is conducted in dangote cement factory in ethiopia, described the effect of fdi in the local community by focusing on two themes labors and landholders. the dangote cement factory in ethiopia has entered into cement production in 2015 with the capacity of 2.5mta. it is the biggest cement producer in the horn of africa in general and in ethiopia in particular. hence, the factory has created a job opportunity for many local labors albeit the factory’s agency subjugated them to pay money to the agency in the form of commission. moreover, the agency was discriminating the right to equal pay for equal work of local labors. this caused the wage difference among local labors who have the same skills, qualification, and experience. on another hand, landholders were evicted from their land without sufficient abdisa olkeba ejssd, v 5 (2), 2018 128 © adama science & technology university https://ejssd.astu.edu.et preparation to resettle them and with inadequate compensation. besides, necessary and continuous training was not given for landholders by concerned bodies on how to save cash and reinvest on investment which can regenerate income for them. further, landholders used to plow their lands and produced grain at least one time per year. likewise, they had no experience of holding cash and used it forever since most of the properties they had were in kinds such as cattle and lands. these all aggravated the current income and necessary and sufficient preconditions livelihood of the local community in addition to inadequate compensation. to alleviate these problems, landholder should be avail first before they are expropriated from their lands. acknowledgment first of all, i would like to thank the reviewers who critically reviewed and commented this manuscript worthily. further, my heartfelt thank goes to my mother, chaltu megersa, who had opened the golden opportunity for me to arrive at this stage and inaugurated the base in my life. moreover, my gratitude also goes to my sister, workinesh olkeba, who supported me both financially and morally. reference amanuel mekonnen (2014). factors affecting fdi flow in ethiopia: an empirical investigation. european journal of business and management, 6 (20). retrieved on february 2018 from www.iiste.org. akinyoade, a. & unche, c. (2016). dangote cement: an african success history? african studies center leiden. retrieved on december 2017 from http://www.ascleiden.nl/?q=content/asc-working-papers. biruhe eshete & thomas gebre (2012). foreign direct investment (fdi) development between the european union (eu) and least developed countries (ldcs) business opportunities in ethiopia. unpublished ma thesis at haagahelia university. diallo, a. & mushinzimana, g. (2009). foreign direct investment in land in mali. gtz press, germany. ethiopian investment commission (2014). ethiopia preferred location for foreign direct investment in africa. free copy. retrieved on february 2018 from http://www.investethiopia.gov.et/images/pdf/. fdre ministry of industry (2015). ethiopian cement industry development strategy 2015-2025. fdre proclamation (2005). expropriation of landholdings for public purposes and payment of compensation proclamation no. 455/2005. http://www.ascleiden.nl/?q=content/asc-working-papers http://www.investethiopia.gov.et/images/pdf/ abdisa olkeba ejssd, v 5 (2), 2018 129 © adama science & technology university https://ejssd.astu.edu.et hale, g. & xu, m. (2016). foreign direct investment effects on the labor market of the host countries. retrieved on november 2017 from http://www.frbsf.org/economicresearch/publications/working-papers/wp201625.pdf. girum abebe, mcmillan, m., serafinelli, m., & verduzco, i. (2016). identifying the local effects of fdi: evidence from ethiopia. retrieved on december 2017 from: http://rcef2016.rofea.org/wp-content/papers/fdi.pdf. gorgen, m., rudloff, b., simons, j., ullenberg, a. vath, s., & wimmer, i. (2009). foreign direct investment in land in developing countries. gtz press, osborn. kurtishi-kastrati, s. 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2017 from http://land.igad.int/index.php/documents 1/countries/ethiopia /investment-1/217structures-opportunities-and-impacts-of-fdi-in-agricultural-sector-in-ethiopia/file. unctad (2014). world investment report, investing in the sdgs: an action plan. united nations, new york, and geneva. wubne mulates (1991). agriculture: a county study in ethiopia. library of congress federal research division. http://www.frbsf.org/economicresearch/publications/working-papers/wp2016-25.pdf http://www.frbsf.org/economicresearch/publications/working-papers/wp2016-25.pdf http://rcef2016.rofea.org/wp-content/papers/fdi.pdf http://land.igad.int/index.php/documents%201/countries/ethiopia%20/investment-1/217-structures-opportunities-and-impacts-of-fdi-in-agricultural-sector-in-ethiopia/file http://land.igad.int/index.php/documents%201/countries/ethiopia%20/investment-1/217-structures-opportunities-and-impacts-of-fdi-in-agricultural-sector-in-ethiopia/file 9 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper isolation of cellulose degrading bacteria from rumen and evaluation of cellulase production potential using lignocellulosic substrate olyad erba urgessa  , yimeslal atnafu sima, ameha kebede, mahafuz mohammed school of biological sciences and biotechnology, college of natural and computational sciences, haramaya university, ethiopia., p. o. box 138, dire dawa, ethiopia article info abstract keywords: bacterial isolate cellulase rumen fluid cmcase wheat straw the utilization of cheaper substrates reduces cost of cellulase production and there is the need for cellulolytic microbes capable of degrading lignocellulosic materials. therefore, this study was aimed to isolate and identify bacteria from rumen fluid, and evaluate wheat straw, sorghum straw and bagasse for cellulase production. rumen fluid were collected from cattle, goat and sheep slaughtered at haramaya town abattoir. wheat and sorghum straw, and bagasse were obtained from haramaya university research plot and wonji-shewa sugar factory, respectively. one-way analysis of variance (anova) was used for data analysis using spss version 20. microscopic and biochemical tests of potential cellulase producers were carried on luria bertoni agar enriched with 1% carboxymethyl cellulose of sodium (cmc-na). cellulase production was evaluated using submerged fermentation. the potential cmc degrading isolate (hug-3b) and (hus-2a) from goat and sheep rumen fluids, respectively, were identified as pseudomonas sp. and isolate (huc-4b) from cattle rumen fluid was identified as aeromonas sp. pseudomonas sp from goat rumen produced significantly the highest carboxymethyl-cellulase (cmcase) and filter-paperase (fpase) of 1.54 ± 0.10 u/ml, 1.46 ± 0.09 u/ml from fermentation of 1% w/v carboxymethyl cellulose used as standard and 1% wheat straw, respectively (p < 0.05), whereas, pseudomonas sp. from sheep rumen produced significantly the highest cmcase of 1.81 ± 0.27 u/ml from fermentation of 1% wheat straw(p < 0.05) and insignificantly highest fpase of 1.27 ± 0.22 u/ml from fermentation of 1% bagasse(p > 0.05). aeromonas sp. produced insignificantly the highest cmcase and fpase of 2.31 ± 0.17 u/ml, 1.50 ± 0.02 u/ml from fermentation of 1% and 2% wheat straw, respectively (p > 0.05). it can be concluded that the fermentation of 1% and 2% wheat straw by aeromonas can be utilized for the maximum production of cellulase. identification of the species or strain of isolate using molecular technique will be recommended. 1. introduction cellulase is an enzyme capable of hydrolyzing β-1, 4-glycosidic bond in cellulose (ekinci et al., 2002). cellulose is an abundant natural biopolymer on earth and most dominating agricultural waste. this cellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bio  corresponding author, e-mail: olyaderba@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.127 products (sadhu and maiti, 2013). cellulases are commonly used in many industrial applications (cherry et al., 2003; kuhad et al., 2011; sadhu and maiti, 2013). cellulases contribute to 8% of the demand in the global enzyme. the cost of using commercial cellulase enzymes is expensive, making it less economical http://www.ejssd.astu.edu/ mailto:olyaderba@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.127 olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 10 (kuhad et al., 2011). the demands for more stable, highly active and specific enzymes grow rapidly (cherry et al., 2003). therefore, the low production cost and good enzymatic activity increase the value of cellulase for commercial use (gao et al., 2008). the utilization of cheaper substrates reduces both substrate cost and usage of costly chemicals for the fermentation procedure (zhang et al., 2006). there are multiple sources of lignocellulosic waste materials from industrial and agricultural processes, e.g., vegetable and fruit peels, sugarcane bagasse, sawdust and agro-residues. the presence of the higher cellulose percentage in many of these wastes makes them cheap sources of substrates for the production of highly demanded cellulase, but the presence of the lignin component slows down the degradation rate (maki et al., 2011). thus, cellulolytic microbes capable of degrading lignocellulosic substrates are needed (kuhad et al., 2011). significant attention has been devoted to the knowledge of cellulase production and the challenges in cellulase research especially in the direction of improving the process economics of various industries (sukumaran et al., 2005; kuhad et al., 2011). one way of improving the economics would be to search for new potent microorganisms that have the ability to consume a variety of carbon sources and the potential to produce higher levels of stable cellulases. in line with this, it was reported that rumen of ruminants harbors various microorganisms that are active in cellulose breakdown (oyeleke and okusanmi, 2008; das and qin, 2012) and thus, it can be an excellent environment for microbial screening for cellulase production. cellulase research has been concentrated mostly in fungi but there is increasing interest in cellulase production by bacteria due to their higher growth rate and thermo stable and alkali stable properties (sadhu and maiti, 2013). evaluation and optimization of various carbon sources was conducted by several researchers for cellulase production using bacterial isolates from different samples (immanuel et al., 2006; sethi et al., 2013; liang et al., 2014; lugani et al., 2015; nandimath et al., 2016). the concentrations and intervals considered for these optimizations were different. therefore, this study was aimed at production of cellulase by isolating and identifying potential cellulase producing rumen bacteria, and evaluating and optimizing the cheap carbon source for the production. 2. material and methods 2.1. collection and preparation of lignocellulosic substrates wheat and sorghum straws were obtained from haramaya university research plot and bagasse was collected from wonji-shewa sugar factory. after washing and drying the samples at 70°c, wheat and sorghum straws were ground in an electric grinder. all samples were stored in polythene bags for subsequent use as fermentation medium (kapoor et al., 2010). 2.2. rumen sample collection fresh rumen fluid of cattle, sheep and goat were collected from haramaya town slaughterhouse under aseptic conditions following methods of begum et al. (2013). the collected rumen fluids were filtered through a layer of muslin cloth. then, the rumen fluid was poured into labeled sterile flasks and kept in a sterilized container at 4°c. 2.3. isolation of cellulase producing bacteria rumen bacteria were isolated directly from each rumen fluid samples by serial dilution technique on luria bertoni agar (lba) plates, ph 7. one ml of filtered each samples was added to 9 ml of normal saline solution in sterile test tubes and serially diluted up to 10-5. an aliquot of 100 μl from 10-5 diluted test tube was transferred using sterile pipette into lba (1 g tryptone, 0.5 g yeast extract and 1 g nacl, 1.5 g agar) and spread using sterile bent glass rod and incubated at 37oc for 48 hrs. after incubation, separated colonies were picked from each plate and separately transferred to fresh luria bertani broth (lbb) and lba consecutively until pure cultures were obtained (ibrahim et al., 2007). the pure isolates appeared on the plates were selected and kept on lba slants at 4°c. 2.4. screening cellulase producing bacteria before the day screening test performed, preserved luria bertoni agar slants (lba) cultures were inoculated into fresh luria bertoni agar (lba) and allowed to grow for 24 hr. the lba medium supplemented with 1% carboxymethyl cellulose was used for screening purpose. single colonies were picked using sterile loop, inoculated and incubated at 35oc for 48 hrs. after incubation, the colonies were screened for cellulase production by flooding the plates with 0.1% olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 11 congo red for 15 min. then, excess dye was discarded and the plate surface was carefully washed with 1 n saline solution (shankar and isaiarasu, 2011). the isolate producing potential cellulase activity was identified by measuring the diameter (mm) of clear zones. the isolates which showed maximum clear zones were kept for bacteriological identification and small scale submerged fermentation. 2.5. identification of potential cellulase producing isolates the potent cellulase producing isolates were first characterized by gram stain and then by biochemical tests such as citrate utilization, methyl red test, motility test, starch hydrolysis, indole production, catalase production, oxidase test, urease production and sugar fermentation tests. the results were compared with bergey’s manual of determinative bacteria for identification (buchanan and gibbons, 1974). the pure culture of identified isolates were grown on screening medium agar slant individually and stored at 4°c with regular sub-culturing (immanuel et al., 2006) and maintained as stock culture from which inoculums were prepared. 2.6. evaluation of cellulase production by the isolate using lignocellulosic substrate cellulase production potential of the isolates using cmc, bagasse, and wheat and sorghum straw were evaluated following modified methods of yang et al. (2014). submerged fermentation medium of 200 ml was prepared from lb broth medium supplemented with 1% w/v cmc-na, ph 7. similarly, the media were prepared by mixing 0.5%, 1%, 1.5%, 2% and 2.5 % w/v of each substrate separately instead of cmc-na in flasks. twenty five (25) ml of the liquid medium was transferred to 100 ml capacity flasks and was autoclaved at 121ºc for 15 min. after cooling, all the flasks containing different substrates were inoculated with 1 ml of suspension of the isolate. then, they were incubated in shaker incubator at 40°c, 120 rpm for 48 hours. afterwards, the cell culture broth was filtered using whatmann no 1 filter paper and then centrifuged at 3000 rpm for 6 min. pellet was discarded while supernatant containing cellulase enzyme was taken to assay cmcase and fpase. 2.7. assay of cellulase activity method described by lokapirnasari et al. (2015) with slight modification was used to assay endo-(1, 4)-β-dglucanase activity. briefly, 0.5 ml of crude cellulase (supernatant) was mixed with 1 ml substrate (1% cmc-na in 0.05 m sodium citrate phosphate buffer at ph 7) and it was incubated in a water bath at 50°c for 30 min. then, 1.5 ml of dns was added into tube and the mixture was placed in 100 °c water bath for 10 min to stop reaction along with control (containing 0.5 ml enzyme mixed with 1.5 μl dns and 1 ml substrate, without incubation at 50 °c for 30 min). the tubes were cooled in ice water for 20 min. absorbance of all the samples was recorded using spectrophotometer at 540 nm. for total cellulase activity determination, modified method of majeed et al. (2016) was used. strip of whatman no.1 filter paper (1x6 cm) was immersed in 1 ml of 0.05 m sodium citrate buffer of ph 7.0. then, 0.5 ml of crude cellulase (supernatant) was added and incubated in a water bath at 50°c for 1 hr and the assay continued as described above. the cellulase activity was determined by using a calibration curve for glucose. one unit of enzyme activity was defined as the amount of enzyme required to form 1 µmol of reducing sugar equivalent to glucose per unit minute under the assay conditions and was calculated from the equation 1 used by ghose (1987). units ml of enzyme = (μmol of glucose)(df) (ve)(t) (1) where, ve is the volume of the enzyme used which was 0.5 ml, t is the reaction time taken in min which was 30 min and df = 1 µmol of glucose produced was determined from enzyme absorbance and standard curve of glucose (equation 2). y = 0.0572 x + 0.0079 in mg ml⁄ (2) by converting the equation in µmol/ml, it becomes equation 3: y = (0.0572 x + 0.0079) × 1000 180 in μmol ml⁄ ) (3) where, y= optical density measured at 600 nm and x = amount of glucose equivalents liberated from cmcna, or filter paper hydrolysis. all the experiments were carried out in triplets. olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 12 2.8. statistical analysis data were analyzed using microsoft excel and statistical package for social sciences (spss) version 20. one-way analysis of variance (anova) was used for analysis. duncan test was used for evaluating significant difference between mean values of three replications at p < 0.05. 3. results 3.1. isolation and identification of cellulase producing bacteria a total of 26 bacterial isolates were obtained from goat, sheep and cattle rumen samples. from the 26 isolates, only five isolate showed clear zones. the diameters of clear zones formed by the isolates were shown in table 1. for each rumen fluid, isolate with the highest clear zone was identified by morphology and biochemical test. morphology and biochemical characteristics of the isolates were shown in table 2. based on biochemical and morphological test results, hug-3b and hus-2a isolates were identified to belong to pseudomonas sp. and huc-4b isolate was identified to belong to aeromonas sp. the indole test demonstrated that huc4b isolate has the ability to decompose tryptophan to indole, pyruvic acid and ammonium (nh4+). when kovac’s reagent was mixed with culture broth, the formed indole was reacted with the reagent and the solution turns from yellow to cherry red. this was showed positive result for indole test. starch hydrolysis test indicated that the isolate has ability to break the starch (amylose and amylopectin) molecules into smaller glucose subunits. when iodine was added to the agar, it reacts with the starch to form a dark brown color and the hydrolyzed area was observed as clear zone around the bacterial growth showing positive for starch hydrolysis (table 2). table 1: top five cellulase producing bacterial isolates with zone of inhibition on congo red stained cmc agar plate s. no samples colony code zone of hydrolysis diameter (mm) 1 goat rumen fluid hug-2b 17.5 2 goat rumen fluid hug-3b 18 3 goat rumen fluid hug-5a 12 4 sheep rumen fluid hus-2a 16.5 5 cattle rumen fluid huc-4b 12 3.2. evaluation of cellulase production by the isolate using lignocellulosic substrate the evaluation and optimization of concentration of carbon source has been carried out by taking five levels of concentrations of wheat straw, sorghum straw and bagasse. the results were shown in figure 1(a), figure 1(b), figure 2(a), figure 2(b), figure 3(a) and figure 3(b). pseudomonas sp. (hug-3b) from goat rumen produced significantly the highest (p < 0.05) cmcase from 1% carboxymethyl cellulose used as standard. next to the standard (1.54 ± 0.10 u/ml), the highest cmcase activity (1.36 ± 0.21 u/ml) was produced at 1% wheat straw content in fermentation medium (figure 1(a)). at 1% substrate content in fermentation medium, the isolate produced significantly the highest (p < 0.05) fpase activity (1.46 ± 0.09 u/ml) from wheat straw as compared to other substrate including 1% carboxymethyl cellulose used as standard (figure 1(b)). pseudomonas sp. (hus-3b) from sheep rumen produced significantly the highest (p < 0.05) cmcase activity (1.81 ± 0.27 u/ml) at 1% wheat straw content in fermentation medium as compared to other substrates including 1% carboxymethyl cellulose used as standard (figure 2(a)). at 1% substrate content in fermentation medium, the isolate produced the highest fpase activity (1.27 ± 0.22 u/ml) in 1% bagasse content in fermentation medium. but, it was not significantly different (p > 0.05) compared to other substrates and concentrations including 1% carboxymethyl cellulose used as standard (figure 2(b)). aeromonas sp. (huc-4b) from rumen cattle produced the highest cmcase activity (2.31 ± 0.17 u/ml) in fermentation medium containing 1% wheat straw, but the value is not significantly (p > 0.05) different from that produced from wheat straw at 1.5 and 2% w/v (figure 3(a)). the highest fpase activity of 1.5 ± 0.02 u/ml was produced at 2% wheat straw content in the medium and the value is not significantly different from that of 1% standard used (figure 3(b)). olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 13 table 2: morphology and biochemical characteristics of the isolates with maximum clear zone. characteristics bacterial isolates hug-3b hus-2a huc-4b gram staining negative negative negative morphology rod rod rod motility test positive positive positive glucose fermentation positive positive positive lactose fermentation positive positive positive sucrose fermentation positive positive positive mannitol fermentation positive positive positive dextrose fermentation positive positive positive arabinose fermentation positive positive positive gas formation negative negative positive citrate utilization positive positive negative urease test positive positive positive indole test negative negative positive catalase test positive positive positive starch hydrolysis test negative negative positive oxidase test positive positive positive methyl red test negative negative positive figure 1: the effect of substrate concentration on cellulase production by pseudomonas sp. (hug-3b). enzyme activity of cellulase extract determined using cmc as substrate (a). enzyme activity of cellulase extract determined using filter paper as substrate (b). 1% cmc in fermentation medium used as standard. error bars represent standard deviation. letters compare means of tree triplicates cellulase activities of substrates across all concentrations level at p < 0.05. figure 2: the effect of substrate concentration on cellulase production by pseudomonas sp. (hus-2a). enzyme activity of cellulase extract determined using cmc as substrate (a). enzyme activity of cellulase extract determined using filter paper as substrate (b). 1% cmc in fermentation medium used as standard. error bars represent standard deviation. letters compare means of tree triplicates cellulase activities of substrates across all concentrations level at p < 0.05. a) b) a) b) olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 14 figure 3: the effect of substrate concentration on cellulase production by aeromonas sp. (huc-4b). enzyme activity of cellulase extract determined using cmc as substrate (a). enzyme activity of cellulase extract determined using filter paper as substrate (b). 1% cmc in fermentation medium used as standard. error bars represent standard deviation. letters compare means of tree triplicates cellulase activities of substrates across all concentrations level at p < 0.05. 4. discussion 4.1. isolation and identification of cellulase producing bacteria in this study, a total of 26 isolate colonies from goat, sheep and cow rumen were tested for cmc-degrading activities. thirteen isolates were able to grow on cmccontaining medium, from which only five isolates showed clear zones (table1). in line with this, pinheiro et al. (2019) reported that the isolates from gastrointestinal tract of giant land snail were able to grow on cmc as their sole carbon sources, but did not display visible degradation halos for cmcase. using cmc-na as the sole carbon source in selective media, followed by the congo red staining method for preliminary isolation of cellulolytic bacterium, is widely considered to be the best method for preliminary screening of cellulolytic bacteria because it is simple and fast (yang et al., 2014). a review paper by sandhu and maiti (2013) concluded that the diameter of the clearing zone may not accurately reflect the true cellulase activity. the maximum clear zone forming isolates, hug-3b, hus-2a and huc-4b from goat, sheep and cattle rumen, respectively, were characterized by morphological and biochemical tests (table 2). based on the microscopic results and comparing biochemical test character with bergey’s manual of determinative bacteriology, the isolate was identified as the pseudomonas sp. (hug-3b, hus-2a), and aeromonas sp. (huc-4b). several studies conducted on screening cellulolytic bacteria from different environments, such as rumen of korean native goat (min et al., 1994), rumen of cow, sheep, and goat (oyeleke and okusanmi, 2008), gut of the ctenopharyngodon idellus (jiang et al., 2011), paper mill sludges (maki et al., 2011), rumen fluid of goat (begum et al., 2013), soil (sethi et al., 2013), rumen of inner mongolia sheep (liu et al., 2014), cecum part of intestine of tibetan pig (yang et al., 2014), rumen fluid waste of bovine abbatoir (lokapirnasari et al., 2015), rumen of labeo rohita (majeed et al., 2016), molasses (islam and roy, 2018) and dumping sites (chakraborty et al., 2019). in these studies, a high cellulolytic degrading isolates were identified as actinomyces sp., pseudomonas sp., aeromonas sp., paenibacillus, paracoccus pantotrophus, pseudomonas fluorescens, fibrobacter succinogenes, bacillus subtilis by-2, enterobacter cloacae, aeromonas bestiarum, aeromonas sp., and aeromonas hydrophila asm-s32, respectively. 4.2. evaluation of cellulase production by the isolate using lignocellulosic substrate the evaluation and optimization of concentration of carbon source has been carried out by taking five levels of concentrations of wheat straw, sorghum straw and bagasse were evaluated. pseudomonas sp. (hug-3b) from goat rumen produced the highest cmcase in fermentation medium containing wheat straw at all levels of concentrations as compared to sorghum straw and bagasse. the isolate produced significantly the highest fpase (1.46 ± 0.09 u/ml) in fermentation a) b) olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 15 medium containing 1% w/v wheat straw as compared to that produced in other concentration of substrates including the standard (figure 1 (a) and (b)). the higher cellulase production from wheat straw is may be because of relatively higher cellulose content in wheat straw as cellulases are inducible enzymes requiring inducer substrate containing cellulose. the highest cmcase (1.36 ± 0.21 u/ml) was produced at 1% wheat straw content in fermentation medium. but, it was significantly lower as compared to that produced in 1% carboxymethyl cellulose used as standard (1.54 ± 0.10 u/ml). this is because of carboxymethyl cellulase is easily soluble and good substrate inducer for endocellulase production (cmcase) by the isolate. evaluating different carbon sources for production of cellulase, min et al. (1994) reported the best cmcase of 0.06 u/ml produced from fermentation of cmc substrate by actinomyces sp. isolated from rumen of korea goat. for pseudomonas sp. (hus-2a) from sheep, the highest cmcase was produced in fermentation medium containing wheat straw at all levels of concentrations (figure 2(a)). the highest cmcase (1.81 u/ml) was produced in 1% wheat straw containing fermentation medium. the isolate produced the highest fpase (1.27 ± 0.22 u/ml) in 1% bagasse (figure 2(b)).this is may be because of the feeding habit of the sheep on fiber foodstuff from which the rumen was collected and bacteria was isolated. in previous study, liu et al. (2014) reported significantly higher cmcase of 62.5 ± 3.0 u/ml and fpase of 30.8 ± 5.4 u/ml produced from fermentation of filter paper by fibrobacter succinogenes isolated from inner mongolia sheep. aeromonas sp. (huc-4b) from cattle rumen produced the highest cmcase in fermentation medium containing wheat straw at all levels of concentrations (figure 3(a)). the highest cmcase of 2.31 ± 0.17 u/ml was produced at 1% wheat straw. significantly, the highest fpase (1.5 ± 0.02 u/ml) was produced by the isolate at 2% w/v wheat straw (figure 3(b)). evaluating the various carbon sources at 1% w/v, islam and roy (2018) reported 0.5 u/ml of cmcase produced from fermentation of cmc substrate by aeromonas sp. isolated from molasses which is significantly less than the present study result for cmc substrate (1.72 ± 0.09 u/ml) at the same level concentration. in another study, chakraborty et al. (2019) reported significantly greater cmcase of 32.8 u/ml from fermentation of 1% w/v cm by aeromonas hydrophila asm-s32 isolated from dumping site compared to any cellulase activity values obtained in this study. for bagasse, the highest fpase of 1.13 ± 0.02 ± 0.22 or 0.15 u/ml was produced at 1.5 and 2 % w/v substrate content in fermentation medium. in previous similar study, the concentrations of bagasse substrate (0.5, 1, 1.5, 2, and 2.5% w/v) were evaluated for cellulase production by aeromonas bestiarum (kf625168) isolated from the gut of labeo rohita and 3.766 u/ml of fpase was produced at 2.5% (majeed et al., 2016). the study results showed that the pseudomonas sp. (hug-3b) and (hus-2a), and aeromonas sp.(huc-4b) exhibited different responses, and the best unit of cmcase enzyme activity was obtained from wheat straw for all isolate and assay types as compared to sorghum straw and bagasse. evaluating different agricultural wastes such as sugarcane bagasse, wheat straw, rice husk, defatted soybean meal, corn cobs and wheat bran at 2% w/v for cmcase production by bacillus subtilis bs06, arshad et al. (2017) reported a different value that of all these tested substrates, maximum cmcase (8.0 ± 0.32 iu) production was from submerged fermentation of sugarcane bagasse. in previous studies, the optimization of concentration of carbon source has been carried out by several researchers for different microbe or microbe isolated and selected from different sample. immauel et al. (2006) evaluated the concentrations of coir substrate (0.5, 0.1, 1.5 and 2% w/v ) for cellulase production by cellulomonas, bacillus and micrococcus spp isolated from coir retting effluents and found that the endoglucanase enzyme activity was more at 1.5% . sethi et al. (2013) evaluated the effect of glucose, lactose, and sucrose at the concentration of (1, 2, 3, 4, 5% w/v) for cellulase production by pseudomonas fluorescens isolated from soil and obtained the maximum cmcase of 1.5, 0.4, 0.7 u/ml at 5%, respectively for all substrates. liang et al. (2014) evaluated the effect of wheat bran concentration of (1, 2, 3, 4, 5, 6, 7, 8, 9, 10 %w/v) for cellulase production by aerobic paenibacillus terrae isolated from soil and obtained the maximum cmcase of 1.4 u/ml at 5%. lugani et al. (2015) evaluated the effect of cmc concentration of (0.5, 1, olyad erba et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 16 1.5, 2, 2.5% w/v) for cellulase production by bacillus sp. y3 isolated from cow dung soil and obtained the maximum fpase and cmcase activity of 3.78 and 4.52 u/ml, respectively at 1%. comparison between the values of this study and the previous ones, there are credible variations among them. some of the values in the previous studies are nearly the same; others are very low and still others very high. according to liu et al. (2014), it is not very consistent to compare the cellulose degradation rates and cellulase activities because of different strains of microbial sp. involved, different kinds of cellulose sources and different procedures of activity determination methods. 5. conclusions the study was conducted to isolate effective cellulase producing bacteria from goat, sheep and cattle rumen fluid. the diameter of halo zone on cmc agar plate showed that hug-3b, hus-2a and huc-4b from goat, sheep and cattle rumen, respectively, were potential cellulase producers. based on the biochemical and morphological characteristics, these strains were identified to be pseudomonas sp. (hug-3b, hus-2a), and aeromonas sp. 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(2006). outlook for cellulase improvement: screening and selection strategies. biotechnology advances, 24(5): 452-481. http://dx.doi.org/10.1155/2014/512497 http://dx.doi.org/10.5402/2013/985685 27 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 lime stabilization of highly plastic clayey soil for the impervious core of embankment dam: the case of gidabo dam, ethiopia feysel husein1 and yadeta c. chemeda2,* 1 dila university, college of engineering and technology, civil engineering program 2 adama science and technology university, school of applied natural science, applied geology program, p. o. box 1888, adama, ethiopia. * corresponding author, e-mail: yadeta.chemdesa@astu.edu.et abstract the stability of different parts of zoned embankment dam including the core has to be guaranteed during design and construction to ensure the overall stability of the structure. selection of appropriate material is a very crucial step. important material properties of the core are low permeability, erosion resistance and cracking resistance. impervious clayey soils are a widely available and used materials for the construction of core of zoned embankment dams in ethiopia. however, such soil is characterized by high compressibility, poor shear strength when compacted and saturated, difficult in moisture control during construction (poor workability) and requires slow rate of construction to allow dissipation of excess pore water pressure. despite their undesirable characteristics, the use of locally found material is becoming more necessary for sustainability reasons. the present study has been, thus, conducted with intention to alter some of the undesirable characteristics of clayey soil using chemical additives. six soil samples from gidabo dam area were collected and different laboratory tests were conducted (i.e. atterberg limits, permeability, compaction, 1dconsolidation, and undrained-unconsolidated (uu) triaxial) tests) on raw samples and after treatment with different percentage of hydrated lime. seven days curing time and the lime addition ratios of 0 %, 2 %, 4 %, and 6 % by dry weight were considered. after lime treatment, the liquid limit, plasticity index and swelling potential decreased. the permeability also decreased by more than one order of magnitude from 4.47 * 10 -6 to 3.63 * 10 -7 . the stiffness and compressibility of the soil increased and reduced, respectively. lime content of 6% has been found to be the minimum lime percentage required to make soils of the study area desirable core fill material. keywords: lime, stabilization, highly plastic clay, embankment, impervious core 1. introduction dam, that is vital for the storage, requires a very detailed geotechnical investigation to ensure design of stable structure and also to select appropriate construction material at the vicinity of the construction site. there are two major types of dam: c o n c r e t e d a m a n d e mb a n k m e n t , depending on the type of mailto:yadeta.chemdesa@astu.edu.et feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 28 © adama science & technology university https://ejssd.astu.edu.et material used for construction (fell et al., 2005). for small scale irrigation and water supply, embankment dam is more economical as construction materials are to be principally supplied near the dam site. an embankment dam, which is sometimes called earth dam, is constructed from earth materials such as soil and rock excavated nearby. the zoned embankment dam has different part: shell, filter and impervious core. the materials used for different part of the dam vary based on the properties of the soil, such as grain size, permeability and density (fell et al., 2005; alonso & cardoso, 2010). rock fill materials (any type of rock) are commonly used for shells and granular materials are used for filters. materials with low permeability, erosion resistant and intermediate to high plasticity to accommodate deformation without risk of cracking are more ideal to be used as a core fill (fell et al., 2005). asphalt, bituminous, concrete and clayey soils are among the different materials that meet the aforementioned properties to be used as impervious core. the major role of impervious core is to control seepage through the body of dame that can lead to failure. in most developing countries, clayey soils are widely used for core of embankment dam because they are very economical and can be easily found in large part of the earth surface as a weathering product of parent rocks. ethiopia is one of the countries with extensive coverage of expansive soil as a result clayey soil is widely used as a core fill material. for instance, tendaho, kesem, koga, ribb, megech, maqa dam, etc are among the different embankment dam in ethiopia where clayey soil were used as a core fill material. although using such soils for core material is more economical as compared to asphalt, bituminous and concrete, their optimal use as a core fill has been limited due to their undesirable properties (yilmaz & erzin, 2004), such as potential for high swelling and cracking, poor workability, low resistance to deformation, etc. according to yilmaz & karacan (1996), to use for core of an embankment dam, the materials preferred to fullfill the following properties: maximum dry density (mmd) > 1.6 g/cm3, optimum moisture content (omc) = 15 – 20%, specific gravity (gs) > 2.6, liquid limits (ll) = 40 – 50% and plasticity index = 14 – 20%. due to the aforementioned reasons, the clayey soils in natural state are least preferred material for core of embankment dam (wanger, 1957) and need to be avoided whenever possible. however, in some places, finding better alternative material may be difficult due to different reasons like shortage of budget. in addition, for both environmental and economic reasons and in a context of circular economy, it is necessary to use local material for construction works. hence, there is a need to find a remedial measure or technique to improve the engineering properties of clayey soils, particularly highly plastic, to make them suitable materials for a core of embankment dam. feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 29 © adama science & technology university https://ejssd.astu.edu.et the most widely recognized form of soil stabilizations, in road construction, is lime treatment as it alters undesirable characteristics of clay minerals (diamond & kinter, 1965; choquette et al., 1987; verhasselt, 1990; he et al., 1995; bell, 1996; al-rawas et al., 2005; al-mukhtar et al., 2010; eisazadeh et al., 2012; pomakhina et al., 2012; maubec et al., 2017; guidobaldi et al., 2017; vitale et al., 2017). however, the potential effectiveness of this technique for the embankment core material need to be checked before implementation in actual field projects. the minimum percentage of lime that need to be added to attain the optimum properties and meet the limits to be used as a core material is among issues that need to be addressed. for fulfillment of this goal, it is necessary to compare the relative desirability as a core material of raw and lime treated clayey soil samples under controlled condition. the present paper, thus, aimed to alter the undesirable characteristics of clayey soils using hydrated lime (ca(oh)2) and to determine the optimum (minimum) lime percentage. the case of gidabo dam is considered in this study and the necessary soil samples (red clay soil) have been collected from the dam site. 2. materials and methods 2.1. location of the project area the project area is located in the southern ethiopia, abaya-chamo subbasin of the rift valley about 17 km from dilla town. the dam site is accessible via addis ababa – dilla asphalt road, which is about 360 km and dilla-gidabo dam site weather road, which is about 17 km. it is geographically located between 6°20' to 6° 25' n and 38° 05' to 38°10' e (figure 1). 2.2. materials for gidabo dam and irrigation project, two clay burrow sites (from upstream (site 1) and downstream (site 2)) were selected as potential sources for the core material (figure 1). a total of six disturbed soil samples were collected from the two clay burrow sites (three from each) for the present study. the hydrated lime used for the present experiment, with purity > 97%, was supplied by derba cement plc. 2.3. experimental approach a series of index and engineering property tests were carried on disturbed and remolded soil at optimum moisture content before and after lime treatment. for lime treatment, desired amount of lime (2%, 4% and 6% by weight of dry soil) was mixed with the air dried soil in the dry state until an even distribution of lime in mixture was obtained. then, mixed by adding water to reach the optimum moisture content. then, the mixture is stored in airtight plastic bag at room temperature for 7 days before and after compaction depending on the type of test. the quantity of lime to be added is calculated according to the following expression: feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 30 © adama science & technology university https://ejssd.astu.edu.et a m e l e k e a m e l e k e a m e l e k e a m e l e k e a m e l e k e a m e l e k e a m e l e k e a m e l e k e a m e l e k e r a b a r a b a r a b a r a b a r a b a r a b a r a b a r a b a r a b a k ilk ile k ilk ile k ilk ile k ilk ile k ilk ile k ilk ile k ilk ile k ilk ile k ilk ile bbbbbbbbb aaaaaaaaa fig. 6.1 construction material sites (soil & rock) of gidabo irrigation project q-2 q-2: quarry s ite -2 giqh-1 legend aaaaaaaaa bbbbbbbbb swampy are a tribute rie s dam axis gidabo rive r borrow s ite -2 sand s ource rock quarry s ite borrow s ite -1 bore hole (giqh-1), quarry s ite -1 0 1 2 kilometres 408000e 410000e 710000n 712000n 714000n 716000n 414000e412000e 1200 m 1 2 0 5 m 12 10 m 1 2 1 5 m 1 2 2 0 m 1 2 2 5 m 1 23 0 m 12 3 5 m 1240 m 12 45 m 1250 m 1 2 5 5 m 1260 m 1 2 6 5 m 12 70 m 1275 m 1280 m 1285 m 1 2 9 0 m 1 2 9 5 m 1300 m 1 3 0 5 m 1 3 1 0 m 1315 m 1 3 2 0 m 1 3 2 5 m 1 33 0 m 1340 m 1 3 4 5 m 1 3 5 0 m 1355 m 1 3 6 5 m 1 3 7 0 m 1 3 7 5 m 1 3 9 0 m 𝐿𝑖𝑚𝑒 % = mass of lime mass of lime + mass of soil ∗ 100% figure 1. map showing the material source sites. burrow site 1 and 2 are a source for clayey core material. all the tests (i.e. grain size distribution, liquid limit, plastic limit, compaction, permeability, strength, and consolidation) were conducted according to astm standards. both liquid limit (based on casagrande method) and plastic limit tests have been performed on soil fraction passing 0.425 mm sieve, after adding a considerable amount of water to moist the soil grain and left for hours. the swelling characteristics of the soil is assessed by determining the free swelling index. the test is performed by slowly pouring 10 cm3 of dry soil which has passed the no. 40 (0.425mm) sieve in to 100 cm3 graduated cylinder filled with distilled water. after 24 hours, final volume of the suspension is recorded. hence, free swell index is calculated using the following expression: 𝐹𝑟𝑒𝑒 𝑆𝑤𝑒𝑙𝑙 𝐼𝑛𝑑𝑒𝑥 % = final volume − initial volume initial volume ∗ 100% the standard proctor compaction tests were done on the investigated soil according to astm d698-98 method a to determine optimum moisture content at which maximum compacted dry density achieved. for the test, soil fraction passing the no. 4.75 mm sieve was soaked overnight. then, they were compacted in a cylindrical mold of 944 cm3 volume (10 cm diameter and 12 cm height) standard proctor mold by repeated blows from the mass of a feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 31 © adama science & technology university https://ejssd.astu.edu.et hammer 2.5 kg falling freely from a height of 30.5 cm. the soils were compacted in three layers, each layer being subjected to 25 blows. permeability and mechanical tests (consolidation and triaxial compression tests) were conducted on one selected soil sample after compaction at optimum moisture content. after compaction, specimens were taken out from the molds and cured at 20°c for 7 days. permeability of the studied samples were determined from the falling head permeability tests following astm d2434 standard. before the commencement of the test, the soil was saturated by allowing water to flow continuously through it from the standpipe. one-dimensional (1-d) consolidation tests were performed in accordance with astm d2435, on specimens trimmed from remolded samples. the test specimens were loaded at twenty-four hour intervals using a load-increment ratio of two, and they were unloaded at twenty-four hour. the triaxial test is the most commonly used method for determining the shear strength of soils in the laboratory. the test was conducted on 38 mm diameter cylindrical sample. the test specimen were prepared from remolded soil which is extruded hydraulically by pushing the soil in to 38 mm diameter tubes and 76 mm in height. 3. result and discussion 3.1. result 3.1.1. initial soil sample characterization the basic physical properties of the studied soil samples are outlined in table 1. all the soil samples under the study are fine grained soil with > 80% of the grains passed through sieve # 200 and liquid limit and plasticity index greater than 50% and 30%, respectively. according to unified soil classification plasticity chart, the studied soils lies above a-line (figure 6) which means the soils are clayey soil with high plasticity (ch). the free swell index ranges from 70% to 90%, which is a typical characteristics of expansive soil. the amount of swelling is known to be dependent on the clay mineral types. soil which contain sufficient amount of montimorillonite tends to swell when they absorb moisture and shrink when they lose moisture. the maximum dry density (mdd) for the soils under the investigation achieved at relatively higher moisture content (24 – 35%), suggesting poor compaction characteristic of the soil. the permeability coefficients of the tested samples ranges from 2.51 * 10-6 to 9.45 * 10-6. the soils are categorized as low to very low permeable soil (head, 1985). the consolidation characteristic of the soil was assessed in terms of the consolidation index (cc). the obtained value of 0.24 for the tested soil is generally a characteristic of medium to high compressible clay soils. feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 32 © adama science & technology university https://ejssd.astu.edu.et table 1: basic properties of soil samples from the six burrow sites property soil samples tp-1 tp-2 tp-3 tp-4 tp-5 tp-6 specific gravity 2.7 2.69 2.75 2.65 2.76 2.69 liquid limit (%) 62.4 68 71.5 65 56 66 plastic limit (%) 28.9 32.4 26.7 24.2 24 19 plasticity index (%) 33.5 35.6 44.8 40.8 32 47 maximum dry density (g/cm3) 1.59 1.55 1.52 1.57 1.37 1.49 optimum moisture content (%) 27.8 26 26.8 24.5 35 35 free swelling index (%) 80 75 90 70 80 70 sand (%) 8 5 5 7 9 8 silt (%) 32 38 40 36 39 38 clay (%) 60 57 55 57 52 54 3.1.2. lime treated soil a) effect of lime on soil plasticity and swelling the effect of lime on the consistency limits (i.e. liquid limit, plastic limit and plasticity index) of the soil is shown in figure 2. with increasing lime content from 0% to 6%, the liquid limit decreased markedly compared to plastic limit, which shows slight increasing trend. the overall effect leads to decrease in plasticity index value. similarly the free swelling index decreased after lime treatment (figure 3). the results of both tests clearly reveal that lime treatment is effective in decreasing water retaining capacity of clayey soil. figure 2. influence of lime on atterberg limits (the values are an average of the six soil samples). ll = liquid limit, pl = plastic limit and pi = plasticity index feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 33 © adama science & technology university https://ejssd.astu.edu.et . figure 3. influence of lime on free swelling index (the values are an average of the six soil samples) b) compressibility characteristics the comparison of 1-d consolidation curves of untreated and lime treated (4 and 6% dry weight) soils are presented in figure 4. the initial void ratio of untreated soil sample is higher than the lime treated soil sample and it decreases with increasing the percentage of stabilizer. the compression index (i.e. the slope of the linear portion of void ratio – log stress curve) also decreased from 0.24 to 0.175 with increasing lime percentage to 6%, implying the compressibility property of the soil improved after lime treatment. figure 4. influence of lime on the compressibility characteristics of soil (tp-1) c) shear resistance the aim of the uu triaxial shear resistance measurements is to assess the improvement of mechanical stability of core material as a result of lime treatment. the results obtained after treatment with different percentage of lime at seven days curing period and compacted at omc are reported on the figure 5. with increasing the lime feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 34 © adama science & technology university https://ejssd.astu.edu.et percentage, the strain-stress curve shifted upward indicating the maximum stress that the specimen can sustain improved after lime treatment. in addition, the treated soil become stiffer or less deformed as indicated by increase of the slope of pre-peak curve. d) hydraulic conductivity the coefficient of permeability, k (determined from falling head test) is used to study the permeability characteristics of treated soil samples. the permeability decreased significantly by one order of magnitude, from 4.47 * 1006 (low permeable) to 3.63 * 10-07 (very low permeable), after lime treatment (figure 6). the effect is more pronounced at lower percentage of lime (2%) and the effect become less with increasing lime content. figure 5. influence of different lime content on the compressive strength of soil (tp-1) figure 6. influence of lime content on the hydraulic conductivity of soil (tp-1) feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 35 © adama science & technology university https://ejssd.astu.edu.et 3.2. discussion the studied soils are characterized by high plasticity, high compressibility and medium to high swelling potential. these properties make such kind of clayey soil less suitable for construction of road, building, dams and other engineering structures. however, the low permeability and self-sealing stability makes it cost effective alternative material for engineering barrier and for the core of embankment dam. apart from permeability, factors like maximum dry density (mmd), optimum moisture content (omc), specific gravity (gs), liquid limits (ll) and plasticity index (pi) governess the suitability of clayey soil for embankment core material (yilmaz & karacan, 1996). except the specific gravity, the other properties of the studied soil do not meet the specified engineering requirement to be used as core fill material. it suggests compaction alone is not sufficient in improving the property of clayey materials since it does not alter the chemistry of clay minerals. after lime treatment with different lime content, the engineering and index properties of the studied soils are improved. the classification after treatment is summarized in figure 7. the untreated soil and 2% and 4% lime treated soils grouped as ch (high plasticity inorganic clay), while the soil is grouped to cl (low plastic inorganic clay) after 6% lime treatment. the cl soil is characterized by medium compressibility, has fair shear strength and good workability as compared to ch soils. according to engineering use chart of wanger (1957) for core of embankment dam, ch soils rated 7 (very low level of desirability), while cl soil rated 3 (good level of desirability). blending with granular material such as sand is an alternative method to improve the property of clayey soil. however, it increases the permeability of the soil. figure 7. uscs classification of raw soil sample and after treatment with lime feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 36 © adama science & technology university https://ejssd.astu.edu.et the liquid limit and plasticity index are compared with the limit suggested by yilmaz & karacan (1996) in table 2. similar to untreated sample, 2% and 4% lime treated soils are also failed to satisfy the limits as the values of liquid limit and plasticity indexes are over the suggested limits. in the case of 6% lime treated soil, however, the parameters meet the limits. therefore, 6% lime has been found to be the minimum lime content required to stabilize the soils of the study area for the desired purpose. the presence of lime nodules in the 7 days cured sample reveals the water content near the optimum moisture content is not enough to dissolve all the lime to keep the pore water ph higher enough to initiate pozzolanic reaction during the curing period. table 2. comparison of the average index properties value with the limit values for core material suggested by yilmaz & karacan (1996) test type limit for core material lime % 0% 2% 4% 6% specific gravity ≥ 2.6 2.71 mmd (g/cm3) ≥ 1.6 1.52 omc (%) 15 20 29 ll (%) 40 50 65 58 52 44 pi (%) 14 20 39 35 26 18 as the results of this work clearly shows, lime treatment is efficient technique in altering undesirable characteristics of high plastic clay soils. the modification of the properties of the lime treated soil is due to two-stage reaction mechanism initiated by lime addition: short-term and long-term reactions (diamond and kinter, 1965; choquette et al., 1987; verhasselt, 1990; he et al., 1995; bell, 1996). immediately as the lime mixed with soil and water, cation exchange begins to take place between the metallic ions associated with the surfaces of the clay particles and the free calcium ions of the lime, which reduces the double layer thickness (film of water) around the clay particles. the compression of diffused electrical double layer in turn leads to the decrease of repulsive potential between clay particles, thus the particles being attracted closer to each other to form flocks. the overall effects are flocculation and particle aggregation, decrease reactivity with water and plasticity, improved workability and reduced volume change characteristics. the long term reaction, unlike to the immediate effect, is initiated by alkaline environment (ph > 12.4) produced by the addition of lime. the high ph facilitates dissolution of clay particles that releases si and al, which together with ca feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 37 © adama science & technology university https://ejssd.astu.edu.et precipitated as hydrated cementious phases (like calcium silicate hydrates (cs-h) and calcium silicate aluminate hydrate (c-s-a-h). the cementation process bounds individual grains together and significantly increases the mechanical strength (increase in stiffness and decrease in compressibility characteristics) of the lime treated soil. the decrease in hydraulic conductivity (k) is also a result of change in the soil texture or decrease of pore size due to cementious gel that formed by pozzolanic reaction. the decrease in permeability has advantage in reducing the risk of internal erosion and ensuring dam stability. 4. conclusion this paper presents the effect of lime treatment on the engineering properties of clayey soils that are selected to be used for the construction of core of gidabo embankment dam. all the soil samples taken from the six identified burrow sites are classified as fine grained high plastic soil (ch) according to uscs classification system. ch soils are characterized by high swelling-shrinkage potential, high compressibility, poor workability and low shear strength when compacted and saturated with water. these properties make ch soil undesirable for construction of core of embankment dam. after lime treatment, however, the engineering properties of the soil improved (i.e. water holding capacity and plasticity reduced, the compressibility reduced, the strength, stiffness and compaction characteristics improved). the minimum lime content required to make the soil of the study area desirable core fill material has found to be 6%. generally, the relative desirability of the soil for the impervious core of embankment dam is improved to rank 3 (good level of desirability) after 6% lime treatment from rank 7 (very low level of desirability). this improvement in engineering properties is due to alteration of the surface chemistry of the clay particles in short-term and cementation of soil particles by calcium silicate and aluminate hydrates in the long-term. the main conclusion of this work is, although the red clayey soil found nearby gidabo dam site and other similar soil types (ch) have some undesirable characteristics, it can be used for the core fill material after mixing with lime (≥ 6%) and compaction at controlled water content (i.e. near to optimum moisture content). in terms of water content, it is recommended to treat the soil at water content higher than optimum moisture content to dissolve the lime nodules. acknowledgment the authors wish to thank adama science and technology university, postgraduate program for providing financial support (mr. fayisal) and laboratory services. the authors also would like to thank gidabo dam project and ethiopian water works enterprise for providing the necessary information about the dam project, laboratory facilities and transportation. feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 38 © adama science & technology university https://ejssd.astu.edu.et reference al-mukhtar, m., lasledj, a., alcover, j-f. (2010). behaviour and mineralogy changes in lime-treated expansive soil at 20 °c. appl. clay sci. 50, 191–198 al-rawas, a.a., hago, a.w., al-samir, h. (2005). effect of lime, cement and sarooj (artificial pozzolan) on the swelling potential of an expansive soil from oman. building and environment, 40, 681 – 687 bell, f.g. (1996). lime stabilisation of clay minerals and soils. eng. geol., 42, 223 – 237 choquette, m., berube, m-a., locat, j. (1987). mineralogical and microtextural changes associated with lime stabilization of marine clays from eastern canada. appl. clay sci. 2, 215–232 diamond, s., kinter, e.b. (1965). mechanisms of of soil-lime stabilization. highway research record, 92, 83–102 alonso, e., cardosos, r. (2010). behavior of materials for earth and rockfill dams: perspective from unsaturated soil mechanics. front. archit. civ. eng. china. doi 10.1007/s11709-010-0013-6. eisazadeh, a., kassim, k.a., nur, h. (2012). solid-state nmr and ftir studies of lime stabilized montmorillonite and lateritic clays. appl. clay sci. 67, 5–10. fell, r., .macgregor, p., stapledon, d., and bell, g. (2005). geotechnical engineering of dams. isbn: 13: 978-0-415-88932-2. guidobaldi, g., cambi, c., cecconi, m., deneele, d., paris, m., russo, g., vitale, e. (2017). multi-scale analysis of the mechanical improvement induced by lime addition on a pyroclastic soil, engineering geology, 221, 193-201. he, c., osbaeck, b., makovicky, e. (1995). pozzolanic reaction of six principal clay minerals: activation, reactivity assessments and technological effects. cement and concrete research, 22, 1691 – 1702 head (1985). permeability and laboratory test methods for the main soil type. maubec, n., deneele, d., ouvrard, g. (2017). influence of the clay type on the strength evolution of lime treated material, appl. clay sci., 137, 107-114. pomakhina, e., deneele, d., gaillot, a.c., paris, m., ouvrard, g. (2012). 29si solid state nmr investigation of pozzolanic reaction occurring in lime treated ca-bentonite. cement and concrete research, 14, 626 – 632 verhasselt, a. (1990). the nature of the immediate reaction of lime in treating soils for road construction. american society for testing and materials stp 1095, philadelphia, 7 – 1. vitale, e., deneele, d., paris, m., russo, g. (2017). multi-scale analysis and time evolution of pozzolanic activity of lime treated clays, appl. clay sci., 141, 36-45. feysel husse. & chemeda y.c. ejssd, v 5 (2), 2018 39 © adama science & technology university https://ejssd.astu.edu.et wagner, a.a. (1957). the use of the unified soil classification system by the bureau of reclamation: proceedings, 4th international conference on soil mechanics and foundation engineering (london), 1, 125. yilmaz, i. and erzin, y. (2004). selection of core material for an earth dam in the lower çekerek basin, tokat, turkey. the electronic journal of geotechnical engineering, 9, bundle: f. yılmaz, i. and karacan, e. (1996). geotechnical characteristics and mineralogy of compacted clays used as an impervious core for the çamlıgöze dam, turkey. international geology review, 38, 972-978. 40 44 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper academic performance characteristics of special boarding students: the case of adama, ethiopia mengistu debele gerbi1,, alemayehu teklemariam2 1department of special needs and inclusive education, ambo university, p. o. box 19, ambo, ethiopia 2addis ababa university, college of education and behavioural studies, department of special needs education article info abstract article history: received 11 march 2020 received in revised form 03 september 2020 accepted 15 october 2020 the main purpose of this study was to investigate academic performance characteristics of oromia development association special boarding school (odasbs) students. to this end, a descriptive correlational research method was employed. purdue academic rating scale (pars) was used to gather data. one hundred odasbs students (male = 56, female = 44) were selected through random sampling technique from grades 9 12. the academic performance characteristics of students were rated by subject-teachers of mathematics, english language, science, and social studies. results of rating students’ academic performance characteristics showed that odasbs students were at excellent level in academic performance in mathematics, english, and science whereas at a strong average in social studies. out of the maximum possible rating scores, this study revealed that the academic performance characteristics rated as 45.42, 44.58, 44.76, and 36.2 for mathematics, english language, science, and social studies subjects, respectively. result of correlation analysis showed that there was positive and significant relationship between mathematics and english language academic performances (r = 0.332, r2 = 0.11%, p < 0.01, df = n – 2 = 98). mathematics academic performance was the leading academic performance characteristics and in no subject, odasbs students fell under average performance. the school, social studies teachers and students should give emphasis to social studies as equal as other subjects. keywords: academic characteristics odasbs pars performance 1. introduction educating superior students in special boarding school is aimed at helping students with high academic ability to grow smartly with an astonishing base that helps them in further learning. hence, education for students with superior academic scores is among academically popular topics all over the world. its popularity has been increasing with an increase in societies’ awareness of the right to education for gifted students (said, 2013; unesco, 1994). thus, the presence of special boarding schools in the country used to protect the right to learn for those students and meant  corresponding author, e-mail: mengistu.debele@ambo.edu.et https://doi.org/10.20372/ejssdastu:v8.i1.2021.212 to realize the goal of appropriate education for all (efa). global experiences indicate that academics at boarding schools operate at very high levels by positively meeting students’ educational needs (bass, 2014). students are encouraged to learn and discuss a wide array of subject matter in special boarding schools. even though the school did not label students as gifted, oromia development association special boarding school (odasbs) is a school for the blending of average, highachiever and gifted students. odasbs is residential type of special boarding school that aimed at maximizing the http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021................ mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 45 academic capacity of students. odasbs established in 2014 as an education division of the oromia development association (oda) that was founded in 1993. the system of oda special boarding school may impact academic performance characteristics of its students. certain scholars have assumed boarding schools as institutions that encompass all spheres of life which enables them to shape the behavior and character of the students. a residential boarding school allows boarding students to engage in a different set of learning activities and interactions with peers and staff which provides opportunities for growth and development of students (holden et al., 2010). regulation and tight scheduling system of boarding school for their students could impact students’ academic performance (cookson, 2009; lee & barth, 2009; williams, 2011). the most common academic characteristic of boarding school students is their superior academic achievement in one or more school subjects. regarding this, martin et al. (2014) stated that boarding school is an environment in which distinct proximal processes are influential. students in boarding schools mainly demonstrate academic characteristics of outstanding performance or potential for superior performance in academics compared to their peers in day schools (martin et al., 2014). thus, special boarding school is meant to educate gifted high-achiever and non-gifted high-achiever students in the same school. this can be strange for scholars who endorse for elite-based traditional boarding schools, but possible to educate these two groups of students in the same school in a single classroom. parents and teachers advocate the idea that gifted and high-achiever students might be best educated in special classrooms or schools (sahin, 2015). it is the current researchers’ ontological philosophical position that education for high-scorer students at special boarding schools in ethiopia should be neither as rigid as elitism nor as floppy as egalitarianism; rather it should be flexible and inclusive. special boarding schools (sbs) have been newly emerged in ethiopia. the establishment of special boarding schools in ethiopia has policy ground. enabling gifted learners in accordance with their potential and needs is among the specific objectives of the ethiopian education policy (moe, 1994). the 1994 etp has confirmed under educational structure no. 2.2.3 that efforts will be made to enable the gifted to learn in accordance with their potential and need (tirussew, 2006). as a result, some regional states have established special boarding schools under their regional educational bureaus (reb). kallamino special boarding school in tigry national regional state is the first of its kind that was established by the tigray development association (tda) in 1998. following this, addis ababa city administration (kotebe science school), oromia national regional state (odasbs), amhara national regional state (dassie special boarding school) and southern nation nationalities and people regional state (hayole special boarding school) have been established. the newly emerging special boarding schools for students with superior academic scores in ethiopia is the focus of this research. sbs education programs are a timely issue to improve the quality of education. the researchers of this study believe that our students with superior academic scores would be significantly benefited from school-wide enrichment programs of special boarding schools that are emerging in different regional states in ethiopia. the objective of this study is to explain the academic performance characteristics of odasbs students. to deal with this objective, the following research questions were addressed. (a) what are academic performance characteristics of oda special boarding school students in specific academic subject areas? (b) what are the inter-subjects correlations of odasbs students’ academic performance characteristics? 2. materials and methods 2.1. research design a correlational research method was employed to study relationships between academic performance characteristics in four subjects. this method was used to determine association among academic performances of odasbs students in four subject areas (mathematics, english, science, and social studies). average academic performances for these subjects were computed to determine students’ performance characteristics. the percentage of students’ academic performance levels for each subject was also computed. scores on purdue academic rating scale (pars) were the variables considered in this study. mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 46 2.2. participants this study was conducted at odasbs that is located in adama, eastern central part of ethiopia. the total population of this study was 595 (male = 366, female = 229) students. simple random sampling via lottery method was used to select 100 (male = 54, female = 46) students. the participants of this study were selected from grade 9, 10, 11, and 12 students at odasbs. twenty students were selected from grade 9, 30 students were selected from grade 10, 24 students were selected from grade 11, and 26 students were selected from grade 12. this was 16.8% of the total population of students. for continuous data with population size = 600, at alpha = 0.05, sample size of 100 is acceptable (mai, 2014). out of 40 teachers at this school, 24 were selected by purposive sampling to participate in the rating of academic performance characteristics of the students. the age of the participants was between 15 and 25. 2.3. instruments the instrument for academic performance characteristics was adapted from pars developed by feldhusen et al. (1990). the items in pars were developed by purdue university instructors from teachers’ classroom observations, from a review of the research literature in each area, and administration of the scales that was directly derived from teachers' classroom experiences with superior students. pars consist of five subjects, but four of them were used in the current study. the four parts of pars used in this study were mathematics, science, english, and social studies. among five subjects on original pars, the only subject not included in the current study was foreign language. this exclusion was due to absence of foreign language subject other than english for grade 11 and 12. grade 9 and 10 students study chinese as foreign language. each of the four subjects has fifteen (15) items. the pars has a total of sixty (60) items in the form of a four-scale likert type. pars has a well-established district line that can be expressed by a quantitative description of data for teacher-rating academic characteristics (performance) of students that expressed by the interval of academic performance. the possible maximum rating score for each subject is 60 whereas the minimum is 15. according to rice (2012), the range of academic ability or limit-line used to categorize students’ academic performance characteristics were indicated as following; below average (< 20), average (20-33), strong average (34-42), excellent (43-51), and superior (5260). for instance, when the rating score is 25 out of 60 on a subject, the student’s performance is at average. cronbach’s alpha (α) reliability for the overall pars with 60 items for the current study was r = 0.707. this instrument was developed based on academic performance characteristics. pars is a culture-fair instrument. hence, the contextual difference would not be significant. thus, the scale was appropriate for ethiopian special boarding school students. 2.4. research procedures academic performance characteristics of students were rated by subject teachers. the teachers have got training on how to rate the students after vivid observation in the classroom and outside the class. it was assured that the teachers know each student a minimum for six months before they assigned to observe them. the observation and filling the rating questionnaire took 25 days. academic performance characteristics of science are filled by biology, physics and chemistry teachers. the scores from these were summed and the average result considered. 2.5. data analysis raters’ responses to instruments were coded based on the 4-point likert scale that worth never (1), sometimes (2), frequently (3), and always (4) in which 4 is the highest and 1 being the smallest rate. using spss program version 23, pearson product-moment correlation analysis was computed to determine relationships between students’ academic performance characteristics in the four subjects 3. results and discussions 3.1. results 3.1.1. descriptive statistics table 1 indicated that odasbs students’ mathematics performance (m = 3.03) was leading characteristics followed by science performance (m = 2.98) and english language academic characteristics (m = 2.97). social studies performance was least among them with (m = 2.41). this implies that lowest attention has been given to social studies. more attention has been given to natural science. this could be the influence of 70%-30% enrollment strategy to higher education, respectively for natural and social streams. mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 47 table 1: descriptive statistics for subject-area academic performance of students (n = 100) subject area mean std. deviation mathematics academic performance 3.0280 0.62072 science academic performance 2.9840 0.73221 english language academic performance 2.9720 0.62769 social studies academic performance 2.4133 0.37665 from table 2, odasbs students’ mathematics academic performance (map) on pars is computed as follow: mean map = 46 + 838 + 1446 + 2212 100 = 45.42 thus, odasbs students’ average mathematics performance was 45.42. this average performance is found between 43 and 51. this makes odasbs students to be labeled in average as excellent students in mathematics performance on pars. specifically, 6% of the students were at average performance, 46% of the students were at a strong average, 12% of the students were at excellent and 36% of them were at a superior level of performance. in another way, 52% of the students (6% + 46%) were shared the tendency of average students whereas 48% of the students (12% + 36%) were shared the tendency of above-average mathematical performance. there was no percent fall below average in mathematical academic performance. from table 3, odasbs students’ english language academic performance (elap) on pars is computed as follow: mean elap = 40 + 834 + 1764 + 1820 100 = 44.58 thus, odasbs students’ average english language academic performance was 44.58. this average academic performance of students is located between 43 and 51. this makes odasbs students to be labeled on average as excellent students in english language performance on pars. specifically, 12% of the students were at average performance, 35% of the students were at a strong average, 29% of the students were at excellent and 24%of them were at a superior level of performance. in another way, 47% of the students (12% + 35%) were shared the tendency of average students whereas 53% of the students (29% + 24%) were shared the tendency of above-average english language performance. there was no percent fall below average in elap. table 2: mathematics performance of odasbs students as rated by 4 teachers (n = 100). item no frequency of valid responses never sometimes frequently always 1 0 44 16 40 2 18 47 19 16 3 0 8 50 42 4 0 39 20 41 5 0 39 21 40 6 0 12 38 50 7 0 14 47 39 8 0 5 55 40 9 1 19 42 38 10 0 36 21 43 11 2 37 23 38 12 10 34 19 37 13 6 38 15 41 14® 9 32 49 10 15 0 15 47 38 total 46 419 482 553 weight 1(46) = 46 2(419) = 838 3(482) = 1446 4(553) = 2212 ® = the item is reversed mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 48 table 3: english language performance of odasbs students as rated by 5 teachers (n = 100). item no frequency of valid responses never sometimes frequently always 1 1 31 50 18 2 0 28 35 37 3 1 29 27 43 4 1 25 41 33 5 0 23 49 28 6 7 28 32 33 7 8 22 40 30 8 1 26 46 27 9 0 24 43 33 10 0 24 42 34 11 0 19 50 31 12 5 48 20 27 13 14 26 38 22 14 1 33 38 28 15 1 31 37 31 total 40 417 588 455 weight 1(40) = 40 2(417) = 834 3(588) = 1764 4(455) = 1820 from table 4, odasbs students’ science academic performance (sap) on pars is computed as follow: mean sap = 488 + 796 + 1392 + 2200 100 = 44.76 thus, odasbs students’ average sap was 44.76. this average performance found between 43 and 51. this makes odasbs students to be labeled in average as excellent students in sap on pars. specifically, 16% of the students were at average performance, 24% of the students were at a strong average, 19% of the students were at excellent and 41% of them were at a superior level of performance. in another way, 40% of the students (16% +24%) were shared the tendency of average students whereas 60% of the students (19% + 41%) were shared the tendency of above-average science performance. there was no percent fall below average in sap. table 4: science performance of odasbs students as rated by 10 teachers (n = 100). item no frequency of valid responses never sometimes frequently always 1 6 29 28 37 2 3 18 40 39 3 15 23 29 33 4 14 17 33 36 5 3 32 24 41 6 4 39 34 23 7 5 38 29 28 8 1 34 29 36 9 8 26 29 37 10 3 28 31 38 11 8 19 38 35 12 3 13 34 50 13 5 29 32 34 14 5 25 19 51 15 5 28 35 32 total 88 398 464 550 weight 1(88) = 88 2(398) = 796 3(464) = 1392 4(550) = 2200 mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 49 from table 5, odasbs students’ social studies academic performance (ssap) on pars is computed as follow: mean ssap = 140 + 1514 + 1338 + 628 100 = 36.2 thus, odasbs students’ average ssap was 36.2. this average performance found between 34 and 42. this makes odasbs students to be labelled in average as strong average students in social studies performance on pars. specifically, 27% of the students were at average performance, 60% of the students were at a strong average, 13% of the students were at excellent and 0% (no percent) of them is at a superior level of performance. in another way, 87% of the students (20% + 60%) were shared the tendency of average students whereas 13% of the students (13% + 0%) were shared the tendency of above-average ssap. there was no percent fall below average in ssap. as table 6 revealed, 94% of students’ academic performance characteristics in mathematics was above average, 84% of students’ academic characteristics in science was above average, 88% of students’ academic characteristics in english language was above average, and 73 % of students’ academic characteristics in social studies was above average. it was inferred from table 6 that about 15% (90 students) of the students were neither gifted nor high-achievers but average students who can attend any regular school. this was computed from the above table 6 in such a way that summing up the results and divide by four (6+16+12+27)/4 =15.25%. due to inappropriate identification, the school loses unnecessary budget on these average performing students. the annual budget per individual student allotted was 30,000 birr. hence, the school loses about 2.7 million birr yearly. about 41.25% of the students were at strong average and about 18.25% of the students were at excellent level. students at strong average and excellent level (41.25% + table 5: social studies performance of odasbs students as rated by 5 teachers (n = 100). item no frequency of valid responses never sometimes frequently always 1 7 54 19 20 2 10 29 35 26 3 11 68 9 12 4 19 22 53 6 5 9 55 29 7 6 1 52 30 17 7 1 43 46 10 8 2 56 37 5 9 0 52 29 19 10 9 58 32 1 11 14 55 20 11 12 48 35 10 7 13 3 57 32 8 14 4 73 22 1 15 2 48 43 7 total 140 757 446 157 weight 1(140) = 140 2(757) = 1514 3(446) = 1338 4(157) = 628 table 6: summary of odasbs students’ academic performance characteristics in percent (%) subject no of students in interval of pars as rated by subject teachers below average [< 20] average [20-33] strong average [34-42] excellent [43-51] superior [5260] mathematics 0 6 46 12 36 science 0 16 24 19 41 english 0 12 35 29 24 social studies 0 27 60 13 0 mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 50 18.25 ≈ 60%) were equivalent to high-achiever students. in similar fashion, about 25% of the students were at superior level which is equivalent to gifted students. 3.1.2. inter-subjects correlation of odasbs students academic performance as table 7 showed, there was moderate positive and significant correlation between mathematics performance and science performance (r = 0.298, r2 = 8.8%, p < 0.01, df = n 2 = 98). there was moderate positive and significant correlation between mathematics performance and english language performance (r = 0.332, r2 = 11 %, p < 0.01, df = n 2 = 98). there was no significant correlation between mathematics performance and social studies performance (r = 0.158, r2 = 2 %, p < 0.01, df = n 2 = 98). there was significant negative correlation between science performance and social studies performance (r = -0.240, r2 = 5.76 %, p < 0.05, df = n 2 = 98). the correlation between performance in english language and performance in science was negative and statistically not significant (r = -0.071, r2 = 0.005 %, p < 0.05, df = n 2 = 98). the correlation between performance in english language and performance in social studies was statistically not significant (r = 0.194, r2 = 0.037 %, p < 0.05, df = n 2 = 98). table 7: pearson product correlations between subjectareas academic performance (n =100). **. correlation is significant at the 0.01 level (2-tailed). *. correlation is significant at the 0.05 level (2-tailed). 3.2. discussions the results of this study reveal that odasbs students perform well in their academics. data from the teacher-rating questionnaire on pars study reveals odasbs students are excellent in all except in social studies. their performances in order from high to low are mathematics = 45.42, science = 44.76, english language = 44.58, and social studies = 36.2. the first three are labeled as excellent performances whereas the fourth is labeled as strong average. the findings of the current study agree with ehioghiren and izehiuwa (2014) that stated boarding school students performed significantly better in mathematics and english language subjects than day school students. three things interact here; relatively good learning environment, high-scorer students (gifted and high-achiever), and their academic performance. according to laiser and makewa (2016), the boarding school learning environment has a direct relationship on academic performance. the results of current study revealed that there are average students, but no student under average in the school. these average students can learn at regular secondary schools rather than sbs. the result of the study indicates that as academic performance in science increase, the performance in social studies decrease (r = -0.240, r2 = 5.76 %, p < 0.05, df = n 2 = 98). as performance in mathematics increase, the performance in science also increase (r = 0.298, r2 = 8.8%, p < 0.01, df = n 2 = 98). there is no significant correlation between mathematics performance and social studies performance (r = 0.158, r2 = 2 %, p < 0.01, df = n 2 = 98). it also shows that there is moderate positive and significant correlation between mathematics performance and english language performance (r = 0.332, r2 = 11 %, p < 0.01, df = n 2= 98). according to rice (2012), students who scored on pars in each subject less than 20 are below average students; 20 33 are average students; 34 42 are strong average students; 43 51 are excellent students; 52 60 are superior students. the inter-subject performance correlation of odasbs students is in range between small and moderate pearson product-moment correlation coefficient. regarding this, cohen (1988) suggests the following guidelines to interpret correlation: small r = 0.10 to 0.29; medium r = 0.30 to .49; large r = 0.50 to 1.0. there is a positive and significant correlation between mathematics and science academic performance (r = .298). the interesting finding of the current study is that the correlation between mathematics and english language performance (r = 0.332) which gives hint for further study for cognitive researchers to revisit the assumption numerical abilities and language ability are performed in different hemisphere of the brain. s/n variables 1 2 3 4 (1) mathematics performance (2) science performance 0.298** (3) english language performance 0.332** -0.071 (4) social studies performance 0.158 -0.240* 0.194 mengistu debele and alemayehu teklemariam ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 51 4. conclusion and recommendations odasbs students have the characteristics of superior students (gifted and high-achiever) as well as strong average in their academic performances. odasbs students are not only gifted and highachievers, but also the blending of gifted, highachievers, and average students. compared to the standard rating scales on pars , odasbs students’ academic performances are excellent in mathematics, english language, and science subjects whereas strong average in social studies. odasbs students’ ssap is least compared with the other three subjects. there are small to moderate inert-subject correlations of odasbs students’ academic performance. based on the foregoing findings the following recommendations are suggested: ‐ the school should give emphasis to social studies as equal as mathematics science and english language. ‐ the academic performance characteristics of odasbs students are promising and have to be shared for regular school students in their respective local areas where odasbs students come from. ‐ the school should set appropriate multiple identification tools in order to spend limited budget on education of superior students. reference bass, l. r. 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(2011). the socialization of the power elite in an american boarding school. senior anthropology thesis, haverford college, pennsylvania. 18 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu review article predictions of climate change impacts on agricultural insect pests vis-à-vis food crop productivity: a critical review daniel getahun debelo  department of applied biology, school of applied natural science, adama science and technology university, p.o.box 1888, adama, ethiopia article info abstract keywords: crop loss global warming greenhouse gases increased temperature pest outbreak climate change is a broad range of global phenomena created predominantly by burning fossil fuels, which add heat-trapping gases called greenhouse gases to earth’s atmosphere. insects are poikilothermic animals and thus sensitive to climate warming. global warming and climate change trigger major changes in diversity and abundance of arthropods, geographical distribution of insect pests, population dynamics, insect biotypes, herbivore plant interactions, activity and abundance of natural enemies, species extinction, and efficacy of crop protection technologies. climate change also will have severe impacts on insects, especially honeybees, which pollinate crop plants and thus affect crop production highly. combined effects of these will increase the extent of crop losses, and thus, will have a major bearing on crop production and food security. prediction of changes in geographical distribution and population dynamics of insect pests will be useful for adapting pest management strategies to mitigate the adverse effects of climate change on crop production. this paper summarized the different ways in which climate change impacts on insect pests and will increase the extent of crop losses. governments should respond to climate change both by reducing the rate and magnitude of change by reducing greenhouse gas emissions (mitigation), and by adapting to its impacts. many impacts can be avoided, reduced or delayed by mitigation, but adaptation will be necessary to address impacts resulting from the warming which is already unavoidable due to past emissions. therefore, there is a need to take a concerted look at the likely effects of climate change on crop protection and devise appropriate measures to mitigate the effects of climate change on food security. 1. introduction the world’s climate has changed frequently during human history. yet the term ‘climate change’ usually refers to those changes that have been observed since the early 1900s and includes anthropogenic and natural drivers of climate (masters and norgrove, 2010). climate change is defined as “a change in the state of the climate that can be identified (for example, by using statistical tests) by changes in the mean and/or variability of its properties, and that persists for an  corresponding author, e-mail: daniel.debelo@astu.edu.net https://doi.org/10.20372/ejssdastu:v7.i1.2020.128 extended periods, typically decades or longer”. this definition is not limited to changes contributed directly or indirectly by human activity. it therefore, includes changes to the climate caused by natural phenomena such as volcanic eruptions. while humans are unable to influence the effects of such natural phenomena on the climate, such events will interact with the influences of human activities. human influences will be superimposed on natural variability (ipcc, 2007). http://www.ejssd.astu.edu/ mailto:daniel.debelo@astu.edu.net https://doi.org/10.20372/ejssdastu:v7.i1.2020.128 daniel getahun ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 19 over the past hundred years, the global temperature has increased by 0.80c (ipcc, 2007). if greenhouse gases concentration continue to rise, future warming is likely to be even more dramatic, with global surface temperatures likely to increase 1.1 6.2°c by the end of this century (diffenbaugh1 et al., 2008). this change is attributed mainly to the overexploitation and misuse of natural resources for various anthropogenic developmental activities such as increased urbanization, deforestation, rising fossil fuel burning and industrialization. these have emitted, and are continuing to emit increasing quantities of greenhouse gases into the earth’s atmosphere. these greenhouse gases include carbon dioxide (co2), methane (ch4) and nitrous oxide (n2o), and a rise in these gases has caused a rise in the amount of heat from the sun withheld in the earth’s atmosphere, heat that would normally be radiated back into space. this increase in heat has led to the greenhouse effect, resulting in climate change (adams et al., 1998). the main characteristics of climate change are increases in average global temperature (global warming); changes in cloud cover and precipitation particularly over land; melting of ice caps and glaciers and reduced snow cover; and increases in ocean temperatures and ocean acidity due to seawater absorbing heat and carbon dioxide from the atmosphere (adams et al., 1998). besides, climate change results in frequent droughts and floods, increased intensity and frequency of heat and cold waves, outbreaks of insectpests and diseases, etc. affecting profoundly, many biological systems and ultimately human beings (fand et al., 2012). higher temperatures will make dry seasons drier, and conversely, may increase the amount and intensity of rainfall; making wet seasons wetter than at present (isman, 1997). climate change is concerned with everyone since it poses potential threat to environment, and agricultural productivity and production throughout the world. it has implications for livelihood and survival of human beings (pareek et al., 2017). crop and livestock yields are directly affected by changes in climatic factors such as temperature and precipitation and the frequency and severity of extreme events like droughts, floods, and wind storms. climate change may also change the types, frequencies, and intensities of various crop and livestock pests (adams et al., 1998). climate and weather patterns are of primary importance for the distribution, development, and population dynamics of insects. insects are coldblooded organisms and hence the temperature of their bodies is approximately the same as that of the environment. therefore, temperature is the most important environmental factor influencing insect behavior, distribution, development, survival, and reproduction. insect physiology is primarily driven by temperature and thus phenology, reproduction, and developmental rates significantly change when populations are exposed to different climatic regimes (tobin et al., 2008; lamichhane et al., 2014). one can safely presume that climate change would be a major causal factor in increasing pest damage to crops. increasing outbreaks of key pests due to changing climate is virtually certain. with regard to food security, increasing pest damage is predicted to result in significant losses in food production and food supplies (ipcc, 2007). pest menace under the influence of climatic factors, at various stages of crop growth is one of the factors limiting agricultural productivity (oerke et al., 1994). most analyses concur that in a changing climate, pests may become even more active than they are currently, thus posing the threat of greater economic losses to farmers (coakley et al., 1999) and insect pests in agricultural systems are the major cause of damage to yield quantity (rosenzweig et al., 2000). insects represent the largest percentage (over 75 %) of the world’s known animal species and there are more than one million species of insects that have been documented and studied by scientists. crop plants used as a food by human beings are damaged by over 10,000 species of insects, and cause an estimated annual loss of 13.6% globally. losses due to insect damage are likely to increase as a result of changes in crop diversity and increased incidence of insect pests due to global warming (sharma, 2010). in the future, pest species are likely to differ in their responses to global warming, changing the relative impacts of pests geographically and among crops. a warmer climate will alter at least two agriculturally relevant characteristics of insect pests. first, an daniel getahun ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 20 individual insect’s metabolic rate accelerates with temperature, and an insect’s rate of food consumption must rise accordingly. second, the number of insects will change, because population growth rates of insects also vary with temperature. the total energy consumption of a pest population (the “population metabolism”) is proportional to the product of these two factors and directly relates to the crop yield loss caused by insect herbivory (deutsch et al., 2018). climate change will affect significantly the diversity and abundance of insect-pests through geographic range expansion, increased overwintering survival and more number of generations per year, thereby increasing the extent of crop losses. it may result in upsetting ecological balance because of unpredictable changes in the population of insect-pests along with their existing and potential natural enemies (ipcc, 2007). 2. ways in which climate change aggravates insect pests the increase in temperature associated with climatic change, would impact crop pest insect populations in several complex ways like expansion of geographic ranges of insect pests, increased over-wintering survival, increase in number of generations and rapid population growth, risk of introducing invasive alien species, increased risk of invasion by migrant pests, impact on pest population dynamics and outbreaks, breakdown of host-plant resistance, changes in insecthost plant interactions, increased incidence of insectvectored plant diseases, reduced effectiveness of biological control agents, disruption of plant-pollinator interactions, and reduced effectiveness of crop protection technologies (diffenbaugh1 et al., 2008; sharma, 2010; fand et al., 2012; pareek et al., 2017). climate change impact on insects is one of the different ways by which it affects global agricultural food production and thus food security. 2.1. expansion of geographic ranges not all places would be affected the same way by climate change. effect of climate change is more in temperate insects, and it permits range expansion. insects have optimal temperature where their population grows best. if the temperature is too cold or too hot, the population will grow more slowly. that is why the losses will be greatest in temperate regions, but less severe in the tropics. temperate regions are not at that optimal temperature, so if the temperature increases there, populations will grow faster, but insects in the tropics are already close to their optimal temperature, so the populations will actually grow slower as the temperature becomes too hot for them (deutsch et al., 2018). any increase in temperature is bound to influence the distribution of insects. it is predicted that a 1ºc rise in temperature would enable speed 200 km northwards (in northern hemisphere) or 40 m upward (in altitude). the areas which are not favorable for insects at present due to low temperature may become favorable with rise in temperature. minimum temperature rather than maximum temperature plays an important role in influencing the global distribution of insect species; hence any increase in temperature will result in a greater ability to overwinter at higher altitudes, ultimately causing a shift of pest intensity from south to north. many insect species have geographic ranges that are not directly limited by vegetation, but instead are restricted by temperature (pareek et al., 2017). geographical distribution of insect pests confined to tropical and subtropical regions will extend to temperate regions along with a shift in the areas of production of their host plants, while distribution and relative abundance of some insect species vulnerable to high temperatures in the temperate regions may decrease as a result of global warming. these species may find suitable alternative habitats at greater latitudes (sharma, 2010). the general prediction is that if global temperatures increase, the species will shift their geographical ranges closer to the poles or to higher elevations and increase their population size (bale et al., 2002). warming in temperate region may lead to decrease in the relative abundance of temperature sensitive insect population. mostly the polar regions are constrained from the insect outbreaks due to low temperature and frequently occurring frosts (volney and fleming, 2000). in the future, projected climate warming and increased drought incidence is expected to cause more frequent insect outbreaks in temperate regions also (fand et al., 2012). distribution of insect pests will also be influenced by changes in the cropping patterns triggered by climate change. major insect pests such as cereal stem borers daniel getahun ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 21 (chilo, sesamia, and scirpophaga), the pod borers (helicoverpa, maruca, and spodoptera), aphids, and white flies may move to temperate regions, leading to greater damage in cereals, grain legumes, vegetables, and fruit crops. changes in geographical range and insect abundance will increase the extent of crop losses, and thus, will have a major bearing on crop production and food security (sharma, 2010). 2.2. pest population dynamics and outbreaks temperature is identified as a dominant abiotic (fleming & volney, 1995) regulating factor for insects, they respond to higher temperature with increased rates of development and with less time between generations. warmer winters reduce winterkill and consequently induce increased insect populations in the subsequent growing season (rosenzweig et al., 2000). global increase in temperature within certain favorable range may accelerate the rates of development, reproduction and survival in tropical and subtropical insects. consequently, insects will be capable of completing more number of generations per year and ultimately it will result in more crop damage (fand et al., 2012). the assessment report from the intergovernmental panel on climate change (ipcc) predicts an increment in mean temperature from 1.1 to 5.4 °c toward the year 2100 (ipcc, 2007). it has been estimated that with a 2°c temperature increase insects might experience one to five additional life cycles per season (ramya et al., 2012). laboratory and modeling experiments support the notion that the biology of insect pests are likely to respond to increased temperatures (fleming & volney, 1995). with every degree rise in global temperature, the life cycle of insect will be shorter. the quicker the life cycle, the higher will be the population of pests (pareek et al., 2017). with temperatures within their viable range, insects respond to higher temperature with increased rates of development and with less time between generations. very high temperatures reduce insect longevity. warmer winters will reduce winterkill, and consequently there may be increased insect populations in subsequent growing seasons. with warmer temperatures occurring earlier in the spring, pest populations can become established and thrive during earlier and more vulnerable crop growth stages (rosenzweig et al., 2000). in increasing temperature, tropical and subtropical insect species may advance continuously pole-ward (as far as their cold hardiness allows) because they lack diapause in their lifecycles. temperate species will expand stepwise, as they need to reach the required temperature to allow them to develop one additional generation before reaching the diapause stage. in fact, diapause introduction is driven by photoperiodic cues (tobin et al., 2008). since warmer temperature will bring longer growing seasons in temperate regions, this should provide opportunity for increased insect damage. a longer growth period may allow additional generations of insect pests and higher insect populations. the mexican bean beetle and bean leaf beetle, both major pests of soybeans, presently have two generations in the u.s. midwest and three in the southeast. an additional generation may be possible in the midwest if the growing season there lengthens (rosenzweig et al., 2000). some pests which are already present, but only occur in small areas or at low densities, may be able to exploit the changing conditions by spreading more widely and reaching damaging population densities. aphids, for instance, key pests of agriculture, horticulture, and forestry throughout the world, are expected to be particularly responsive to climate change because of their low developmental threshold temperature, short generation time, and considerable dispersal abilities (sutherst et al., 2007). projections of insect-crop dynamics through the 21st century suggest increases in pest pressure over much of the american midwest, which could result in substantial increases in pesticide use to maintain productivity (taylor et al., 2018). crop losses will be most acute in areas where global warming increases both population growth and metabolic rates of insects, primarily in temperate regions, where most grain is produced. as the climate warms and temperatures rise, we might lose more crops to insects. with warming climate insects’ metabolism speeds up, and the faster they burn energy, the more they eat and reproduce. that means a greater number of increasingly hungry insects feeding on our staple crops. using a mathematical model, scientists were able to predict just how much damage they could do: for every degree celsius rise in temperature, insects could do an daniel getahun ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 22 extra ten to twenty-five percent of damage to wheat, maize, and rice. reduced yields in these three staple crops are a particular concern, because so many people around the world rely on them. together they account for 42 % of direct calories consumed by humans worldwide. increased crop losses will result in a rise in food insecurity, especially in those parts of the world where it is already rife, and could lead to conflict (deutsch et al., 2018). 2.3. increased incidence of insect-vectored plant diseases it has been reported that, global climate warming may lead to latitudinal and altitude wise expansion of the geographic range of insect-pests (parry and carter, 1989), increased abundance of tropical insect species (diffenbaugh et al., 2008), decrease in the relative proportion of temperature sensitive insect population, more incidence of insect-transmitted plant diseases through range expansion and rapid multiplication of insect vectors. climate change creates new ecological niches, potentially allowing for the establishment and spread of plant pests and diseases to new geographical areas and from one region to another. accordingly, it might also result in the emergence of new plant diseases and pests (fahim et al., 2013). climate change will also result in increased problems of insect-transmitted diseases through range expansion and rapid multiplication of insect vectors. these changes will have major implications for crop protection and food security, particularly in the developing countries, where the need to increase and sustain food production is most urgent (pareek et al., 2017). thus, with changing climate it is expected that the growers of crops have to face new and intense pest problems in the years to come (fand et al., 2012). higher temperatures and greater precipitation in some regions are likely to result in the spread of plant pests and diseases. higher temperatures reduce insect winterkill, and lead to increased rates of development and shorter times between generations. wet vegetation promotes the germination of spores and the proliferation of bacteria, fungi, and nematodes. prolonged droughts can encourage other pests and diseases; especially those carried by insects (rosenzweig et al., 2000). increased temperatures, particularly in early season, have been reported to increase the incidence of viral diseases in potato due to early colonization of virusbearing aphids, the major vectors for potato viruses in northern europe (fand et al., 2012; pareek et al., 2017). 2.4. risk of introducing invasive alien species increasing temperatures and other alterations in weather patterns (e.g., drought, storm events) resulting from climate change are likely to have significant effects on outbreaks of pests and pathogens in natural and managed systems, and are also expected to facilitate the establishment and spread of invasive alien species (backlund et al., 2008). even though the causes of biological invasions are manifold and multifaceted, changes in abiotic and/or biotic components of the environment (climate change, biological control) are recognized as primary drivers of species invasion (ipcc, 2007). invasion of new insectpests will be the major problem with changing climate favoring the introduction of insect-susceptible cultivars or crops (gregory et al., 2009). invasive insect, disease and weed pests are likely to benefit most from climate change, leading to increased pesticide and herbicide use or greater reductions in yield (masters and norgrove, 2010). 2.5. disruption of plant-pollinator interactions the economic significance of pollination is underscored by the fact that about three-quarters of the world’s flowering plants depend on pollinators, and that almost a third of the food that we consume results from their activity. the majority of pollinators are insects, whose distributions, phenology, and resources are all being affected by climate change (backlund, 2008). pollination is one of the 15 major ecosystem services, a foundation for human life on earth (kannan and james, 2009). many of the economically important crops (murugan, 2006) and majority of the flowering plants require insect pollinators like flies, butterflies, moths, beetles and especially bees for their reproduction and formation of fruits and seeds. pollination is currently under threat from mounting pressures exerted by growing population, depleting natural resource base and global climate change (fand et al., 2012). earlier studies have clearly shown that the population abundance, geographic range and pollination daniel getahun ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 23 activities of important pollinator species like bees, moths and butterflies are declining considerably with changing climate (fao, 2008). the climatic factors like temperature and water availability have been found to affect profoundly the critical events like flowering, pollination and fruiting in the life cycle of plants (cleland et al., 2007). the majority of the flowering plants require insect pollinators like flies, butterflies, moths, beetles and especially bees for their reproduction and formation of fruits and seeds. honey bees are perhaps the best known pollinators because of their floral fidelity. insect pollination, mostly by bees, is necessary for 75% of all crops that are used directly for human food worldwide. thus, entomophilous pollination is a fundamental process for the production of about one-third of the world human food (klein et al., 2007). some insects also contribute directly to the human economies through valuable products like silk by silk worms; lac by lac insects; and honey, wax and other products by honeybees (murugan, 2006). many pollinators have synchronized their life cycles with plant phenological events. impending climate change is expected to disrupt the synchrony between plantpollinator relationships by changing the phenological events in their life cycles and may thus affect the extent of pollination. the quality and the quantity of pollination have multiple implications for food security, species diversity, ecosystem stability and resilience to climate change (fao, 2008). 2.6. impact on crop-pest interactions the increasing temperature and co2 have been found to exert both bottom-up and top-down effects on the tri-tropic interactions between crops, insects and natural enemies by means of certain physiological changes especially related to host-suitability and nutritional status. the co2 enriched environment reduces the nitrogen content of the plant tissue due to widening of carbon: nitrogen (c: n) ratio, thus cause a slight decrease in nitrogen-based defenses like alkaloids and in turn may increase in carbon-based defenses such as tannins. this enhances the feeding by insect herbivores in order to obtain sufficient nitrogen for their metabolism. ultimately, it slows down the insect development and increases the length of life stages resulting in more foliage feeding than the normal (fand et al., 2012). 3. reduced effectiveness of crop protection technologies host-plant resistance, bio-pesticides, natural enemies, and synthetic chemicals are some of the potential options for integrated pest management. however, the relative efficacy of many of these pest control measures is likely to change as a result of global warming. global warming will also reduce the effectiveness of host plant resistance, transgenic plants, natural enemies, biopesticides, and synthetic chemicals for pest management (sharma, 2010). 3.1. breakdown of host plant resistance host plant resistance is one of the ecofriendly options for managing harmful insect-pests of crops wherein the plant can lessen the damage caused by insect-pests through various mechanisms like antixenosis, antibiosis and tolerance. however, expression of the host plant resistance is greatly influenced by environmental factors like temperature, sunlight, soil moisture, air pollution, etc. under stressful environment, plant becomes more susceptible to attack by insect-pests because of weakening of their own defensive system resulting in pest outbreaks and more crop damage. thermal and drought stress associated breakdown of plant resistance have been widely reported. with global temperature rise and increased water stress, tropical countries like india may face the problem of severe yield loss in sorghum due to breakdown of resistance against midge stenodiplosis sorghicola (coq.) and spotted stem borer chilo partellus swinhoe (fand et al., 2012). 3.2. reduced effectiveness of biological control agents biological control of insect-pests is one of the important ecofriendly components of integrated pest management. natural enemies of crop pests mainly, predators, parasitoids and pathogens are prompt density responsive in their action subjected to the action of abiotic components. being tiny and delicate, natural enemies of the insect-pests are more sensitive to the climatic extremes like heat, cold, wind and rains. precipitation changes due to climate change can also affect predators, parasites and pathogens of insect-pests resulting in a complex dynamics. with changing climate, incidence of entomopathogenic fungi might be daniel getahun ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 24 favored by prolonged humidity conditions and obstinately be reduced by drier conditions. thus, climate change can affect the natural enemies negatively, reducing their pest control efficacy. the effects of climate change are expected to act directly on all the trophic levels as well as indirectly on soil, water, the host crop, and hyper parasitoids (fand et al., 2012). 4. implications of climate change for food security climate change has serious impacts on diversity, distribution, incidence, reproduction, growth, development, voltinism and phenology of insect pests. climate changes also affect the activity of plant defense and resistance, biopesticides, synthetic chemicals, invasive insect species, expression of bt toxins in transgenic crops. considering such declining production efficiency due to depleting natural resource base, serious consequences of climate change on diversity and abundance of insect-pests and the extent of crop losses, food security for 21st century is the major challenge for human kind in years to come pareek et al., 2017). the greatest challenge for humanity in the coming century is to double the present levels of food production to meet the needs of ever increasing population by sustainable use of shrinking natural resource base (deka et al., 2008). the aggravating pest problems under changing climate regimes are expected to intensify the yield losses; threatening the food security of the countries with high dependency on agriculture (ipcc, 2007). the climate change is likely to affect the extent of entomophilous pollination by disrupting the synchrony between plant-pollinator life cycles (kudo et al., 2004), with an estimated risk of reduction in world food production by one-third (klein et al., 2007). this has major implication for food and nutritional security (fao, 2008). this may have direct bearing on the livelihood of the rural poor as their survival is directly linked to outcomes from food production systems. the increased food prices resulting from declining food production may also impact negatively the urban population (fand et al., 2012). 5. conclusion it has been noted that insect population under increasing temperature is under move towards higher altitudes and elevation. various insect responds differently to atmospheric temperature and carbon dioxide rise and it is obvious of having varied impact depend on insect and regions. due to the climate change there is an increase in number of insect pest population, out breaks of insects and increase in number of insect generations. this would definitely increase the damage caused by the insect, decrease the crop yields, increase the cost on crop protection and thereby affect the economy. further, as with temperature, precipitation changes can impact insect pest, predators and parasitoids resulting in a complex dynamic situation. climate change could upset the balance between insect crop pests and their natural enemies particularly in tropics leading to more frequent outbreaks (kambrekar et al., 2015). impacts of climate change on crop production mediated through changes in populations of serious insect-pests need to be given careful attention for planning and devising adaptation and mitigation strategies for future pest management programs. therefore, there is a need to have a concerted look at the likely effects of climate change on crop protection, and devise appropriate measures to mitigate the effects of climate change on food security. the current escalated use of fossil fuels which contributes to increased production of greenhouse gases and increase atmospheric co2 concentration that enhances increase of 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(2000). climate change and impacts of boreal forest insects. agriculture, ecosystems & environment, 82: 283-294. http://www.mdpi.com/journal/agronomy https://www.journals.elsevier.com/agriculture-ecosystems-and-environment https://www.journals.elsevier.com/agriculture-ecosystems-and-environment 1 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper molecular docking analysis of antibacterial indole alkaloids from roots of brucea antidysentrica tewabech alemu, kebede shenkute, rajalakshanan eswaramoorthy, solomon girmay, yadessa melaku, milkyas endale  department of applied chemistry, school of applied natural science, adama science and technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 8 january 2020 received in revised form 25 february 2020 accepted 13 march 2020 brucea antidysentrica is one of the medicinal plants used traditionally to treat various diseases such as leprosy, wound, diarrhea, fever, eye disease, rabies and tumor/cancer. phytochemical screening test of dichloromethane/methanol (1:1) and methanol extracts revealed the presence of alkaloids, tannins, flavonoids, steroids and saponins, terpenoids, and phytosterols. silica gel column chromatographic separation of dichloromethane/methanol (1:1) and acid-base extracts afforded compound 1, canthin-6-one (2) and 1,11dimethoxycanthin-6-one (3). the crude extracts and isolated compounds were screened for in vitro antibacterial activity against strains of salmonella thphimurium, escherichia coli, bacillus subtilis and staphylococcus aureus. canthin-6-one (2) and 1,11-dimethoxycanthin6-one (3) exhibited promising antibacterial activity against e. coli and s. thphimurium (12.6±0.6 and 12.5±0.87 mm zone of inhibition, respectively) compared to ciprofloxacin (27.3±2.52 and 29±1.00 mm, respectively), at 0.5 mg/ml. the radical scavenging activity of dichloromethane/methanol (1:1) and acid-base extract were 83.3 % and 80 %, respectively, whereas alkaloids 1-3 displayed activity of 85.3 %, 87.5 % and 78.4 % at 100 µg/ml, respectively, suggesting that canthin-6-one (2) displayed promising radical scavenging activity. the molecular docking analysis showed compound 1 and 1,11-dimethoxycanthin-6one (3) were found to show hydrogen bond interaction with active site amino acid residue phe196 and ala 51 at a distance of 1.5 ao and 1.5 ao, respectively. hydrophobic interactions were observed between 2 and 3 with val201, lys57, gly200, asn198, ala51, leu52 and asn198, leu52, val201, lys57, respectively, suggesting the compounds may act as potential inhibitors of dna gyrase enzyme. keywords: antibacterial activity brucea antidysentrica alkaloids antioxidant activity molecular docking 1. introduction plants have nutritional value, in the eye of local people, medicinal and ritual or magical values (abbink, 1995; pearce and puroshothaman, 1992; schippman et al., 2002; cragg and newman, 2005). over the years research on traditional medicine contributed to discovery of several lead drugs (adhikari et al., 2010;  corresponding author, e-mail: milkyas.endale@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.184 saiprasana et al., 2012; ugochukwu et al., 2013). brucea antidysentrica (simaroubaceae, figure 1) is a species of flowering shrub/tree growing up to 7 m tall growing widely in tropical africa-guinea and nigeria, east to ethiopia and south to angola, malawi and zambia, usually at the edge of semi-humid forests at relatively http://www.ejssd.astu.edu/ mailto:milkyas.endale@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 2 high altitudes (hedenberg and edvans, 1989). in ethiopia, the plant is known by local name aballo (amharic) and qomonyo (afan oromo) (endashaw, 2007). preparation made from different parts of the plant is used to treat various conditions such as leprosy, wound, diarrhea, fever, eye disease, rabies and tumor/cancer, among others (fullas, 2001). previous reports revealed that the genus is rich in quassinoids having wide spectrum of biological activities such as antitumor, antiviral, antiparasitic, herbicidal and antioxidant (viswanad et al., 2011; alves et al., 2014). we hereby report isolation, spectroscopic identification, antibacterial, antioxidant evaluation and molecular docking analysis work done on the roots of b. antidysentrica. figure 1: picture of b. antidysentrica (picture taken by tewabech alemu on feb. 28, 2019) 2. materials and methods 2.1. general tlc was performed using precoated aluminum backed supported silica gel 60 f254 (0.2 mm thickness) and glass supported silica gel 60 f254 (1.0 mm thickness), respectively. alkaloids were detected on tlc stained with the mayer reagent. column chromatography was carried out using silica gel 60-120 mesh astm. the ultraviolet and visible (uv-vis) spectrum was taken on spectroscopic genesys™ 2pc uv-vis scanning spectrometer. the infrared (ir) data were recorded on a perkin elmer model ftir spectrometer as kbr disks. 1h and 13c nmr data were obtained in cdcl3 on a bruker avance 400 mhz. 2.2. plant material collection and identification the roots of b. antidysentrica were collected from the amhara region, east gojam zone, dejen woreda 236 km from addis ababa on february 28, 2019. the plant was identified by the botanist shamble alemu, national herbarium of ethiopia, addis ababa university (voucher code ta-001/2011). the roots were cut into small pieces, air-dried, and ground into a fine powder. 2.3. extraction and isolation air-dried root powder was weighed (350 g) and extracted exhaustively with dichloromethane/methanol (1:1) for 72 hr at room temperature. the marc left was further extracted with 2 l methanol soaked for 72 hr at room temperature. the mixture was filtered, and concentrated under reduced pressure at 50°c using rotary evaporator to afford 12.77 g (3.65%) and 9.4 g (2.68%) crude extracts, respectively. roots powdered (350 g) of b.antidysentrica was extracted in n-hexane (3 l) separately; the solution was filtered and the residue was extracted with ethanol (2 l) at room temperature for 72 hr. then solvent was evaporated by using a rotary evaporator at 50oc to yield crude ethanol extract. the defatted ethanolic crude extract was suspended in 5% hcl to ph 5, pre-saturate with water and partition by adding chloroform, the extract was separated in to two layers. then aqua and organic layers were separated by using separatory funnel three times. the acidic aqueous phases was basified by adding 5% nh3 to ph 11, and partitioned by chloroform. aqueous and organic layers were separated by using separatory funnel three times. the chloroform extracts were combined, and concentrated under vacuum rotary evaporator to obtain brown crude extract (5.1 g, 1.46%). the crude dichloromethane/methanol (1:1) extract (10 g) was adsorbed on 10 g of silica gel and subjected to silica gel (150 g) column chromatographic separation. elution was carried out with increasing gradient of ethyl acetate in n-hexane. a total of 221 fractions were collected each concentrated under reduced pressure to dryness. fractions that showed similar rf values and the same characteristic color on tlc were combined. fractions 29-31 afforded single spot (compound 1) on tlc (etoac/n-hexane, 1:1, rf value of 0.44, 30 mg), fractions 51-54 which showed single spot (canthin-6one, 2) on tlc (etoac/n-hexane 9:1, rf value 0.57, 25 mg) and fractions 84-87 afforded the same single spot (1,11-dimethoxycanthin-6-one, 3) on tlc (etoac/nhexane 8:2, rf value of 0.41, 30 mg). tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 3 2.4. phytochemical screening test 2.4.1. test for flavonoids: to dcm:meoh (1:1) and meoh crude extracts (0.5 g each), 10 ml of ethyl acetate was added and heated for 3 min using steam bath. the mixture was filtered, and the filtrate was mixed with 1 ml of dilute ammonia solution. formation of intense yellow color ratifies the presence of flavanoids (sofowora and debiyi, 1978). 2.4.2. test for saponins: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 5 ml of distilled water was added and shaken while heating to boil. frothing showed the presence of saponins (evans and trease, 1989). 2.4.3. test for phenols: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 5 drops of 2 % of fecl3 were added and formation of bluish green to black color indicates the presence of phenols (roopashree et al., 2008). 2.4.4. test for tannins: the crude extracts (dcm: meoh (1:1) and meoh extract) (0.5 g each) were boiled in 10 ml of water in a test tube and filtered. to the filtrate, 5 drops of 0.1 % fecl3 were added to give a brownish green or a blue-black color which confirms the presence of tannins (ayoola et al., 2008). 2.4.5. test for terpenoids (salkowski test): dcm/meoh (1:1) and meoh crude extracts (0.5 g) were mixed with 2 ml of chloroform and 3 ml concentrated h2so4 carefully to form a layer. a reddish brown coloration of the interface was formed to show positive results for the presence of terpenoids (ugochukwu et al., 2013). 2.4.6. test for steroids: to dcm/meoh (1:1) and meoh crude extracts (0.5 g), 10 ml of chloroform and 10 ml of concentrated h2so4 were added by sides of the test tube. the upper layer turns red and h2so4 layer showed yellow with green fluorescence (alhadi et al., 2015) indicating the presence of steroids. 2.4.7. detection of phytosterols (salkowski’s test): crude extracts (dcm: meoh (1:1), meoh, 0.5 g each) were treated with a few drops of chloroform and filtered. to the filtrate, few drops of concentrated h2so4 was added, shaken, and allowed to stand appearance of the golden yellow color indicates the presence of triterpenes (roopashree et al., 2008). 2.4.8. test for glycosides (modified borntrager’s test): crude extracts (dcm: meoh (1:1), meoh, 0.5 g each) were treated with fecl3 solution and immersed in boiling water for about 5 min. the mixture was cooled and extracted with equal volumes of benzene. the benzene layer was separated and treated with ammonia solution and formation of the rose-pink color in the ammonical layer confirms the presence of anthranol glycosides (roopashree et al., 2008). 2.5. antibacterial testing 2.5.1. preparation of discs containing extracts the same concentrations of 0.5 mg/ml were prepared from the extract, isolated pure compounds and the standard. the sample was applied into sterile agardisc and dried at 37°c. the agar disc was weighed carefully to confirm the exact amount of the extract and isolated pure compounds being incorporated (compared to preweighed blank discs). 2.5.2. bacterial culture escherichia coli was isolated from stool specimens in the clinic and identified according to routine cultural properties and biochemical tests. four strains of each were included in the study. a few colonies from the overnight culture of eosin methylene blue (emb) agar was transferred into approximately 4-5 ml tripticase soy broth (tsb) medium. the broth was incubated at 37°c for 3-4 hr, and the turbidity of suspension was adjusted to that of 0.5 mcfarland barium sulfate standards. the standard suspension was used for both qualitative and quantitative antibacterial assays. 2.5.3. bacterial susceptibility testing standardized inoculums (0.5 mg/ml) were introduced on to the surface of sterile agar plates, and a sterile glass spreader was used for even distribution of the inoculums. sterile agar-disc diffusion previously soaked in a known concentration of extract or pure compound (0.5 mg/ml per disc) was carefully placed at the center of the labeled seeded plate. the same procedure was used for all the mrsa strains used. the plates were incubated aerobically at 37°c and examined for zones of inhibition after 24 hr. the inhibition zones were measured with a ruler and compared with the control disc (disc containing only physiological saline). strains of human pathogen microorganisms used in this study were as follows: two gram-negative bacteria, escherichia coli, salmonella thphimurium and two gram-positive bacteria staphylococcus aureus and tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 4 bacillus subtilis. the bacterial stock cultures were incubated for 24 hr at 37°c on nutrient agar medium (adama science and technology university, department of applied biology, adama). the bacterial strains were grown in the mueller–hinton agar (mha) plates at 37°c. the agar was melted (50°c), and the microorganism cultures were then added aseptically to the agar medium at 45°c in plates and poured into sterile petri dishes to give a solid plate. all these experiments were performed in triplicate. the plates were incubated for 24-48 hr at 37°c for bacteria. the inhibition zones produced by the plant extracts were compared with the inhibition zones produced by commercial standard antibiotics (ciprofloxacin). one dilution (0.5 mg/ml) of b. antidysentrica extract, pure compound, and standard drugs were prepared in dmso using nutrient agar tubes. mueller–hinton sterile agar plates were seeded with indicator bacterial strains (1.3 *108 cfu/ml) and allowed to stay at 37°c for 3 hr. control experiments were carried out under similar conditions by using ciprofloxacin for antibacterial activity as a standard drug. the zones of growth inhibition around the disks were measured after 24 hr of incubation at 37°c for bacteria. the sensitivities of the microorganism species to the plant extract and isolated pure compounds were determined by measuring the sizes of inhibitory zones (including the diameter of disk) on the agar surface around the disks, and values <6mm were considered as not active against microorganisms. dmso used as negative control during the whole test on bacteria. the results are calculated as averages of triplicate tests (murai et al., 1995). 2.6. antioxidant activity the dichloromethane/methanol (1:1) extract was dissolved in four vials containing methanol to give 500, 250, 125 and 62 µg/ml. to each 1 ml of the above extracts, 4 ml of 0.04% dpph was added and four vials with concentration of 100, 50, 25 and 12 µg/ml were prepared. the resulting solution was placed in an oven at 37oc for 30 min and subjected to uv-vis spectrophotometer to record absorbance at 517 nm. this was repeated for the acid-base extracts and isolated compounds. the percentage dpph inhibition was calculated according to equation 1 (maksyutina, 1971). % 𝑜𝑓 𝑟𝑎𝑑𝑖𝑐𝑎𝑙 𝑠𝑐𝑎𝑣𝑒𝑛𝑔𝑖𝑛𝑔 𝑎𝑐𝑡𝑖𝑣𝑖𝑡𝑦 = 𝐴𝐵𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 − 𝐴𝐵𝑎𝑛𝑎𝑙𝑦𝑡𝑒 𝐴𝐵𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 ∗ 100 (1) 2.7. molecular docking study of isolated compounds in this study, isolated compounds were subjected to molecular docking studies using the adt version 1.5.2 and auto dock version 4.2 docking program to investigate the potential binding mode. the crystal structure of the enzyme (phe196 and ala51) with resolution 2.3 å was chosen as the protein model. the structures of ligands were optimized using the hyperchem 7.0 software. auto dock version 4.2 was used to prepare the molecules and parameters before submitting it for docking analysis with auto dock. polar hydrogen atoms were added while non-polar hydrogen atoms were merged and then, gasteiger partial atomic charges were assigned to the ligands. all rotatable bonds of ligands, defined by default of the program, was allowed to rotate during the automated docking process and then prepared protein and ligand structures were saved in the pdbqt format suitable for calculating energy grid maps. a grid box size of 46×46×46 å points with a grid spacing of 0.375 å was considered. lamarckian genetic algorithm (lga) program with an adaptive whole method search in the auto dock was chosen to calculate the different ligand conformers. after 200 independent docking runs for each ligand, a cluster analysis was done. in according to the root mean square deviation (rmsd) tolerance of 2.0 å conformations was clustered and ranked by energy of which the conformation with the best scored pose with the lowest binding energy was selected for these ligands (mansourian et al., 2015; morris et al., 1998). 3. results and discussions extraction of the roots of b.antidysentrica by acidbase extraction approach, dichloromethan/methanol (1:1), and methanol solvents afforded 5.1 g (1.46%), 12.77 g (3.65%), 9.4 g (2.68%) yields, respectively. 3.1. phytochemical screening phytochemical screening test of dichloromethane/ methanol (1: 1) and methanol roots extracts revealed the presence of alkaloids, flavonoids, phytosterols, phenols, steroids, tannins, terpenoids, glycosides and saponins (table 1). the findings of this test are in good agreement with the type of secondary metabolites reported earlier from the genus (narihiko et al., 1986; blech and budzikiewicz, 1994; ouyang et al., 1994) and these compounds might be responsible for the traditional medicinal use of the genus. tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 5 table 1: phytochemical screening tests of crude extracts phytochemical screening test dcm:meoh (1:1) meoh 100% flavonoids alkaline test + + saponins froth test + + phenols ferric chloride test + + tannins gelatin test + + terpenoids salkowski’s test + + steroids + + phytosterols salkowski’s test + + glycosides modified borntrager’stest + + alkaloids + + 3.2. characterization of compounds compound 1 was obtained as a brown solid (melting point: 155°c) with an rf value of 0.44 (n-hexane/etoac (1:1) as eluent). a positive mayer’s test was observed suggesting that the compound was an alkaloid. the ir (kbr disk) spectrum showed broad and sharp vibrations at 3441 and 1744 cm-1 attributed to hydroxyl (oh) and carbonyl moiety, respectively. the absorption bands at 1637, 1462 and 1230 cm-1 suggest the presence of aromatic system (c=c), c=n and c-o stretching vibrations, respectively. the presence of symmetric and asymmetric c-h stretching are clearly evident from vibrations at 2854 and 2927 cm-1, respectively. the 1h nmr (400 mhz, cdcl3, table 2) spectrum revealed the presence of proton signals at δh 8.82 (d, h13, d, j = 12 hz), 7.98 (d, h-1, j = 4 hz), 8.66 (d, h-4, j = 12 hz), 7.00(d, h-4’, j = 8), 8.09 (d, h-3’, j = 8 hz), 7.55 (h-6, t) and 7.72 (h-7, t). the presence of doublet of doublet peak was observed at δh 8.09 (h-3’) suggest allylic and ortho coupled with δh 7.98 (h-1) and δh 7.00 (h-4’). the 13c nmr and dept-135 spectra revealed a total of 20 well resolved carbon peaks. the presence of eleven aromatic carbon groups, one methylene (c-6’), one methyl and seven quaternary carbon atoms (of which four of them are aromatic carbon) are all evident. the existence of carboxylic acid carbonyl carbon at δc173.5 (c-9) and sp2 oxygenated quaternary carbon at δc 159.5 (c-2') are clearly marked (table 2). the peaks at δc 67.8 and 62.3 suggest oxygenated methylene and methyl signals forming ch2-o-ch3 moiety, also supported by dept-135 spectrum, where the former peak is pointing down whereas the later pointing up. peaks at δc 139.2 and 145.5 suggest olefinic methine near to heteroatom, preferably next to nitrogen, supported by dept-135 spectrum. the above spectral data and comparison with literature revealed that the compound is indole alkaloid derivative of flazin methyl ether (1, figure 2) previously isolated from juice of ribes nigrum l. (blech and budzikiewicz, 1994). however, this is the first report of the compound from roots of b. antidysentrica. n h n oh o 1 34 5 8 o o 13 10 11 2' 4' 5' 6' 1 n h n oh o 1 34 5 8 o o 13 10 11 2' 4' 5' 6' 1a figure 2: structure of compound 1 and flazin methyl ether (1a) tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 6 table 2: 1h nmr, 13c nmr and dept-135 spectral data of compound 1 in cdcl3. position compound 1 flazin methyl ether (blech and budzikiewicz, 1994) 1h (δ in ppm and j in hz) 13c dept-135 1h (δ in ppm and j in hz) 13c 1 7.98 (1h, d, j=4) 145.5 145.5 137.1 3 130.7 132.2 4 8.67 (1h, d, j= 4) 117.3 117.3 8.85 (1h, s) 115.9 5 7.98 (1h, d, j=8) 127.9 127.9 8.41 (1h, d, j=7.8) 122.0 6 7.55 (t) 128.1 128.1 7.34 (1h,dd,j=7.8/8.2) 120.5 7 7.72 ( t) 129.1 129.1 7.65 (1h,dd,j=7.8/8.2) 128.9 8 7.00 (1h,d, j=8) 116.5 116.5 7.82 (1h, d, j=8.2) 112.9 10 139.6 141.5 11 124.3 120.9 12 127.10 129.9 13 8.82(1h, d, j=4) 139.2 139.2 132.0 2’ 159.5 151.7 3’ 8.09 (1h, dd, j=8, 4) 116.5 116.5 7.45 (1h, d, j=3.4) 111.1 4’ 7.00 (1h, d, j=8) 116.5 116.5 6.77 (1h, dd, j=3.4) 111.9 5’ 159.5 153 co 173.5 166.5 ch2 3.96 (2h, s) 68.7 68.7 4.64 (2h, s) 65.5 ch3 3.31(3h,s) 62.3 62.3 3.34(3h, s) 57.2 compound 2 was isolated as yellowish amorphous solid with mpt of 149oc and rf value of 0.57 (etoac/nhexane (4:1) as eluent). a positive mayer’s test was observed suggesting that the compound was an alkaloid. the ir (kbr) spectrum of the compound showed a broad vibration at 3451 cm-1, sharp vibrations at 2924 cm-1 and 2854 cm-1, 1637 cm-1, and 1400 cm-1 attributed to amine group (n-h), sp3 h-c, sp2 c-h, imine bond c=n and c=c bonds, respectively. the 1h nmr spectrum showed peaks at δh 8.07 (h-4, d, j = 7.8 hz), 7.54 (h-10, t, j = 8 hz), 7.72 (h-9, t, j = 8 hz) and 8.82 (h-2, d, j = 8 hz), 7.98 (h-1, d, j = 8 hz), 7.00 (h-5, d, j = 8 hz) and 8.11 (h-11, d, j = 8 hz). the 13c nmr and dept-135 spectra of showed the presence of fourteen carbon signals including aromatic peaks between δc 116.5-159.5, of which six of them are sp 2 quaternary at δc 159.5 (c-6), 139.5 (c-13), 136,09 (c16), 132.06 (c-15) , 130.5 (c-14) and 124.36 (c-12). upfeild chemical shift of carbonyl carbon at δc 159.5 (c-6) suggest that the carbonyl group is directly linked to nitrogen of indole moiety and it is also α,β-conjugated (δc 139.4 (c-4) and 129.0, c-5) suggesting that the compound have β-carboline alkaloid canthine-6-one skeleton. the cosy spectrum supported correlations between h1↔h2, h4↔h5, h8↔h9, h9↔h10 and h10↔h11 (table 3). the hsqc spectrum suggested direct connectivity between h1→c1, h2→c2, h4→c4, h5→c5, h8→c8, h9→c9, h10→c10, and h11→c11 (table 3). the hmbc spectrum showed correlations between h1→c2,9,12; h2→c1,15,16; h4→c6,9; h5→c-6,16; h8→c12; h9→c11,13; h10→c8,12 and h11→c-3,15 (table 3) in good agreement with canthine-6-one alkaloids. thus, based on the above spectral data and comparison with literature (ouyang et al., 1994), compound 2 was suggested to be identical with canthin-6-one (figure 3) previously isolated from roots of brucea mollis (ouyang et al., 1994). compound 3 was isolated as yellowish amorphous solid with melting point of 180oc and rf value of 0.41 (etoac/n-hexane (4:1) as eluent). the ir spectrum of compound showed the presence of amine group (n-h) at 3400 cm-1, c-h band at 2924 cm-1, c=o band at 1744 cm-1, c=c and c=n at 1644 cm-1 and c-n at 1398 cm-1. the 1h nmr spectrum (table 4) revealed the presence of methoxy protons as singlet at δh 4.08 (3h) and 4.23 (3h), and aromatic protons at δh 8.5 (s, h-1), 8.38 (d, j tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 7 = 8 hz, h-8), 7.97(d, j = 8 hz, h-4), 7.65 (t, j = 8 hz, h-9), 7.01(d, j = 8 hz, h-5) and 6.86 (d, j = 12 hz, h10). the 13c nmr and dept-135 spectrum (table 4) showed two methoxy carbon atom signals appearing at δc 57.7 and 56.2. the presences of eleven aromatic peaks were observed at δc 160.4, 155.9, 151.3, 140.1, 139.2, 132.1, 132.9, 131.6, 130.5, 113.1, 109.8 and 107.9. in agreement with the spectral data of canthine-6-one (2), up-feild chemical shift of carbonyl carbon at δc 160.4 (c-6) suggests that the carbonyl group is directly linked to nitrogen of indole moiety and it is also α,βconjugated (δc 139.15 (c-4) and 125.1 c-5) suggesting that the compound have β-carboline alkaloid canthine6-one skeleton. close inspection of the 2d nmr spectra (table 4) showed the following correlations. cosy spectrum showed correlations between aromatic protons appearing at δh 7.97 (h-4) and δh 6.86 (h-5), δh 8.38 (h-8) and δh 7.65 (h-9), δh 7.65 (h-9) and δh 7.01 (h10). hsqc spectrum showed 1j correlations between aromatic protons and their respective carbons h2→c2, h4→c4, h5→c5, h8→c8, h9→c9, h10→c10, and methoxy groups (h17→c17 and h18→c18). hmbc spectrum (table 4) showed correlations between h2→c1,11,14; h5→c6,9,16; h8→c10,12; h10→c11,8,12. the hmbc spectrum also indicated correlations of the methoxy protons at δh 4.23 (h-17) and 4.08 (h-18) with c-11 and c-1, respectively, confirming their location at c-1, 11 of the canthine-6-one skeleton. thus, based on table 3: 1h, 13c, dept-135, cosy, hsqc and hmbc spectral data of canthin-6-one (2, figure 3) position compound 2 canthin-6-one (ouyang et al., 1994) 1h (δ in ppm and j in hz) 13c dept-135 cosy hsqc hmbc 1h (δ in ppm and j in hz) 13c 1 7.98 (1h, d, j=8) 116.4 116.5 h1↔ h2 h1→c1 h1→c2,12,15 7.59(1h, d, j=5) 115.4 2 8.82 (1h, d, j=5) 145.7 145. 7 h2→c2 h2→c1, 14,16 8.58(1h, d, j=5) 144.8 4 8.07 (1h, d, j=8) 139.4 139.4 h4↔ h5 h4→ c4 h4→ c6,15,16 7.77(1h, d, j=9.7) 138.6 5 7.00 (1h, d, j=8) 129.0 129.0 h5→c5 h5→ c6,16 6.75(1h, d, j=9.7) 127.9 6 159.5 158.2 8 8.69 (1h, dd, j=8,4) 117.3 117.3 h8 ↔ h9 h8→c8 h8→ c12 8.28(1h, d, j=7.7) 116.3 9 7.72 (1h, t) 130.9 130.9 h9 ↔ h10 h9→c9 h9→ c13 7.45(1h, t) 129.8 10 7.54 (1h, t) 125.7 125.7 h10↔ h11 h10→c10 h10→ c8,12 7.28(lh, t) 124.7 11 8.11 (1h, dd, j=8,4) 122.7 122.7 h11→ c11 h11→c13,14 7.73(1h, d, j=7.7) 121.6 12 124.4 123.3 13 139.5 138.2 14 130.5 128.9 15 132.1 130.9 16 136.1 135.2 n n o 1 2 4 56 8 12 13 14 15 16 11 n n o 2 figure 3: structure of canthine-6-one (2) tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 8 table 4: 1h, 13c, dept-135, cosy, hsqc and hmbc nmr spectral data of 1,11-dimethoxychan tin-6-one (3). n n o och3 h3co n n o och3 h3co 1 2 4 6 8 11 12 13 14 15 16 17 18 3 figure 4: structure of 1,11-dimethoxycanthin-6-one (3) the above spectral data and extensive comparison with literature, the compound was identified as 1,11dimethoxycanthin-6-one (3, figure 4), previously reported from stem of b. antidysentrica (narihiko et al., 1986). 3.3. antibacterial activity the antibacterial activity of the crude extracts and alkaloids (1-3) were examined at a concentration of 0.5 mg/ml against four pathogenic bacterial strains two gram-positive (staphylococcus aureus, bacillus subtilis) and two gram-negative (escherichia coli and salmonella thphimurium). antibacterial potential of crude extracts and alkaloids (1-3) were assessed in terms of zone of inhibition of bacterial growth (table 5). the results revealed that the isolated compounds showed promising antibacterial activity against s. aureus, b. subtilis, e. coli and s. thphimurium. canthine-6-one (2) showed medium activity (12.66±0.6 and 12.33±2.31) against e. coli and s. thphimurium, respectively, compared to ciprofloxacin (27.3±2.52 and 29±1.00). 1,11-dimethoxycanthin-6-one (3) showed promising antibacterial activity (12.5±0.87 and 12.3±1.65 mm) against s. thphimurium and b. subtilis compared to ciprofloxacin (29±1.00 and 33.3±3.22 mm). the dcm:meoh (1:1) crude, acid-base crude extract and compound (1) showed moderate antibacterial activity against s. aureus, e. coil, s. thphimurium and b. subtilis, respectively. position compound 3 cosy hsqc hmbc 1,11-dimethoxychantin-6-one (narihiko et al., 1986) 1h (δ in ppm and j in hz) 13c dept-135 1h (δ in ppm and j in hz) 13c 1 155.9 155.6 2 8.5 (1h, s) 132.1 132.1 h2→ c2 h2→c1,9,11,14 8.41 (1h, s) 131.3 4 7.97(1h,d,j=8) 139.15 h4↔ h5 h4→c4 7.91(1h,d,j=10) 139.0 5 6.86(1h,d,j=8) 131.6 125.1 h5→ c5 h5→ c6,16 6.79(1h,d,j=10) 131.8 6 160.4 160.2 8 8.38(1h,dd,j=8,4) 109.8 109.8 h8↔ h9 h8→ c8 h8→ c10,12 8.29(1h,d,j=8) 109.5 9 7.65(1h,t, j=8) 125.1 131.6 h9 ↔ h10 h9→ c9 h9→ c11,13 7.54(1h,t, j=8) 124.8 10 7.01(1h,dd, j=8,4) 107.9 107.9 h10→c10 h10→ c12,8 6.86(1h,d,j=8) 107.5 11 151.3 151.0 12 113.1 116.6 13 132.9 132.6 14 113.1 112.8 15 130.5 130.2 16 140.1 h2→ c2 h2→c1,14,16 139.8 och3 4.23(3h,s) 57.7 57.7 h17→ c11 4.16(3h,s) 57.4 och3 4.08(3h,s) 56.2 56.2 h18→ c1 4.0(3h,s) 56.0 tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 9 3.4. antioxidant activity in the dpph scavenging assay, crude extracts and alkaloids (1-3) were investigated through the free radical scavenging activity via their reaction with the stable dpph radicals. the reduction of the dpph was followed via the decrease in absorbance at 517 nm. the dpph radical scavenging activities (in %) of extracts and isolated compounds were found to be 87.5 (canthine6-one, 2), 85.3 (compound 1), 83.3 (dcm:methanol (1:1) crude extract), 80.00 (acid-base crude extract), 78.4 (1,11-dimethoxycanthin-6-one, 3) at 100 µg/ml (table 6). it was observed that the dpph scavenging activity increased with increasing concentration of the samples. for the various concentrations, canthine-6-one (2) exhibited the highest percent inhibition of the dpph compared to ascorbic acid which showed maximum scavenging effect at very low concentration (figure 5). table 5: zone of bacteria growth inhibition diameter (mm) sample (0.5 mg/ml) inhibition diameter (mm) ±sd e. coli s. thphimurium b. subtilis s. aureus methanol/dichloromethane (1:1) extract 11.6±1.53 10.66± 1.15 11.33±1.15 9.33±0.58 acid-base extract 11.33±2.08 11.0±1.73 12.0±3.74 11.33±0.58 derivative of flazin methyl ether (1) 11.33±0.58 11.66±3.06 11.33±1.53 11.0±1.00 canthin-6-one (2) 12.66±0.60 12.33±2.31 11.0±0.707 9.6±1.16 1,11-dimethoxycanthin-6-one (3) 11.3±0.58 12.5±0.87 12.3±1.65 10±1.00 ciprofloxacin 27.3±2.52 29±1.00 33.6±3.22 23.5±0.58 sdstandard deviation table 6: % of scavenging activity of the extracts and isolated compounds of b. antidysentrica a = absorbance 0 20 40 60 80 100 60 65 70 75 80 85 90 95 100 d pp h sc av en gi ng a ct iv ity (% ) concentration(µg/ml) dcm:meoh acid-base compound 1 compound 2 compound 3 ascorbic acid figure 5: dpph scavenging activity (%) of b. antidysentrica extracts, isolated compounds and positive reference (l-ascorbic acid). c (µg/ml) samples dcm:meoh(1:1) extract acid-base extract 1 2 3 a % scavenging activity a % scavenging activity a % scavenging activity a % scavenging activity a % scavenging activity 100 0.2 83.3 0.26 80 0.15 85.3 0.1 87.5 0.28 78.4 50 0.3 75 0.27 79.2 0.23 77.4 0.2 83.3 0.31 76.1 25 0.35 70.8 0.3 76.9 0.3 70.5 0.3 75 0.34 73.8 12 0.4 66.6 0.4 69.2 0.4 60.7 0.38 68.3 0.45 65.4 tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 10 table 7: docking score of dna gyrase protein and alkaloids (1-3). 3.5. molecular docking in association with in vitro antibacterial activity, molecular docking studies were performed for three alkaloids in order to predict the orientation and binding affinity of ligand molecules at the active site of receptor with bacterial enzyme dna gyrase. in docking study, all the compounds were found to have minimum binding energy ranging from -5.8 to -4.8 kj/mol (table 7). on comparative basis alkaloids (1-3) revealed minimum binding energy of -5.8, -5.7 and -5.7 kcal/mol, respectively (table 7). these molecules were unwrapped by active site amino acid residues at the active site pocket region (as shown in figure 6a-c). the protein (dna-gyrase) comprises of fourteen active site residues, which are promiscuous to the ligands. out of which only two (phe198 and ala 51) residue is directly interacting with the ligands. the other residues in close proximity to the inhibitor are hydrophobic in nature. "compound (1) and 1,11-dimethoxycanthin-6-one (3) were found to show hydrogen bond interaction with active site amino acid residues phe196 and ala 51 at a distance of (1.5ao), respectively.. the yellow dashed line indicates a possible hydrogen bond formed between the connections residues (figure 6a-c) and red color also indicated the hydrogen bond interaction (figure 7a-c). canthin-6-one (2) had no hydrogen bond interaction with the protein. compound (1) showed two hydrophobic interactions with try 218 and glu 219, canthin-6-one (2) showed six hydrophobic interactions with amino acid residues val201, leu 52 lys57, gly200 asn198 and ala52 and 1,11dimethoxycanthin-6-one (3) showed four hydrophobic interactions with asn 198, leu52, val201 and lys57. all ligands displayed no pi to pi and pi to cation interactions with the protein. dna gyrase is an essential bacterial enzyme that catalyzes the introduction of negative (-) supercoils into chromosomal and plasmid dna. gyrase was discovered soon after it was clear that in vitro recombination of bacteriophage λ required a negatively supercoiled dna substrate. dna gyrase cleave and relegate dna to regulate dna topology and are a major class of antibacterial drug targets (reece and maxwell, 1991). the docking of alkaloids (1-3) with dna gyrase showed higher binding affinity as well as hydrogen bonding and good hydrophobic interaction with the receptor. thus, from this study it can be concluded that the compounds 1-3 may act as potential inhibitors by hindering the function of dna gyrase enzyme. figure 6a: molecular docking of compound 1 with dna gyrase receptor. mode compound 1 canthin-6-one (2) 1,11-dimethoxycanthin-6-one (3) affinity (kcal/mol) dist from best mode affinity (kcal/mol) dist from best mode affinity (kcal/mol) dist from best mode rmsd i.b. rmsd u.b. rmsd i.b. rmsd u.b. rmsd i.b. rmsd u.b. 1 -5.8 0.000 0.000 -5.7 0.000 0.000 -5.7 0.000 0.000 2 -5.5 8.225 10.733 -5.7 22.422 25.040 -5.3 1.873 4.233 3 -5.5 1.802 5.669 -5.6 1.130 3.936 5.2 2.391 4.508 4 -5.4 8.135 11.181 -5.5 12.175 13.368 -5.0 15.021 16.977 5 -5.3 2.110 3.485 -5.3 22.536 25.215 -5.0 15.786 17.759 6 -5.3 7.920 11.682 -5.2 14.292 15.937 -4.9 16.498 18.132 7 -5.3 23.777 26.168 -5.2 14.977 16.780 -4.8 16.396 18.263 8 -5.1 7.742 10.427 -5.2 14.559 0.000 -4.8 13.336 15.474 9 -5.1 8.762 11.879 -5.1 14.289 25.040 -4.8 14.126 16.244 tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 11 figure 6b: molecular docking of canthin-6-one (2) with dna gyrase receptor. figure 6c: molecular docking of 1,11-dimethoxycanthin-6one (3) with dna gyrase receptor. figure 7a: molecular docking of compound 1 with hydrophobic and hydrogen bond interactions. figure 7b: molecular docking of canthin-6-one (2) with hydrophobic and hydrogen bond interactions. figure 7c: molecular docking of 1,11-dimethoxycanthin-6one (3) with hydrophobic and hydrogen bond interactions. 4. conclusion for decades traditional medicines have been used and continue to be an alternative approach on treatment for various diseases. due to the growing interest of consumers in substances of natural origin coupled with the increasing apprehension surrounding potentially harmful infectious diseases, our group did a comprehensive phytochemical analysis on the roots of b. antidysentrica. silica gel column chromatographic separation of the crude extracts led to isolation of three indole alkaloids which are identified as compound 1 (derivative flazin methyl ether), canthin-6-one (2), and 1,11dimethoxycanthin-6-one (3) all of which are identified for the first time from the species. in addition, compound 1 was isolated for the first time from the genus. the antibacterial test results revealed that the tewabech alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 12 isolated compounds showed promising antibacterial activity against s. aureus, e. coli, s. thphimurium, and b. subtilis. compound 1 and canthin-6-one (2) exhibited medium (12.66±0.60 and 12.5±0.87 mm zone of inhibition) antibacterial activity against e. coli and s. thphimurium compared to that of ciprofloxacin (27.3±2.52 and 29±1.00 mm zone of inhibition). canthin-6-one (2) had strong dpph free radical scavenging activity (87.5% at 100 µg/ml) compared to ascorbic acid. molecular docking analysis revealed good scoring pose (lowest energy) with value of -5.8 kcal/mole, -5.7 kcal/mol and -5.7 kcal/mol for alkaloids 1-3, respectively. the finding of these pharmacologically important secondary metabolites, the observed biological activity supported by molecular docking analysis and free radical activity support the traditional use of the plant to treat various infectious diseases. conflict of interest the authors declare that there is no conflict of interests regarding the publication of this paper. data availability statement all spectral data can be freely accessed from supporting information. acknowledgment the authors acknowledge adama science and technology university (astu), adama, ethiopia for funding part of the work. mr. temesgen asefa (staff of department of applied biology, astu) is duly acknowledged for his assistance during antibacterial tests. reference abbink, j., (1995). medicinal and ritual plants of the ethiopian southwest: an account of recent research, indigeneous knowledge and development monitor, 3: 6-8. adhikari, b.s., babu, m.m., saklani, p.i., rewat, g.s., (2010). medicinal plants diversity and their conservation status in wild life institute of indi (wii) campus, deheadun, ethnobotanical leaflet, 14:6-56. alhadi, e.a., khalid, h.s., alhassan, m.s., kabbashi, a.s., noor, o.m., (2015). antimicrobial and phytochemical screening of cordia africana in sudan,” world journal of pharmacological research, 4(3):257-269. alves, b.s., miranda, m.h., soares, a.l., randau, p.k., (2014). simaroubaceae family: botany, chemical composition and biological activities. rev. bras. farmacogn. 24: 481-501. ayoola, g.a, coker, h.a.b., adesegun, s.a., 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male and female wmss were counted by the use of stereo microscope and recorded as number of live wms. folimat showed maximum pest population reduction followed with closer 240. however, some non-target insects were found dead on trees treated with folimat, an observation to be confirmed by further investigation. incorporating the less toxic insecticide, closer 240 sc which showed a certain degree of the pest population reduction, in to integrated pest management to control the white mango scale infestation on big trees of mango landrace is recommended. keywords: gudetu arjo landrace mango scale mortality 1. introduction mango (mangifera indica l.) is grown across the world in tropical and sub-tropical countries. it is the third most important fruit crop in the tropics next to citrus and banana (louw et al., 2008). mango is consumed as a fresh fruit and in different forms of beverages (griesbach, 2003; nabil et al., 2012). mango possesses anti-oxidant, cardiotonic, hypotensive, anti-inflammatory and antispasmodic properties, and as a result plays vital role in ethnopharmacology and various chemical industries (wauthoz et al., 2007; kayode and sani,  corresponding author, e-mail: ofgaa.djirata@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.239 2008; masibo and he, 2008; nwinuka et al., 2008; shah et al., 2010). moreover, mango is a significant foreign currency generating crop for many countries across the globe (unctad, 2016). in ethiopia mango is produced mainly at small scale level primarily for family consumption and local fresh fruit markets (alemayehu chala et al., 2014). however, large scale mango productions for juices and export markets are currently being introduced in to the sector (wiersinga and jager, 2009; yilma tewodros, 2009). http://www.ejssd.astu.edu/ mailto:ofgaa.djirata@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx http://www.unctad.org/ ofgaa djirata. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 87 mango being a crop of such vital economic importance, its production is constrained by a variety of pests and pathogens. medina and garcía (2002) depicted that over 492 species of insects, 17 species of mites and 26 species of nematodes were reported to have been damaging mango plantations. mango pests include insects such as fruit fly complex, mango seed weevil, thrips, mealy bugs and scale insects; and non-insect pests such as mites, among others. moreover, pathogenic fungi and bacteria cause diseases to the crop (usda, 2006). likewise, mango production in ethiopia is challenged by a variety of pests and diseases (alemayehu chala et al., 2014, ayantu tucho et al., 2014). tewodros bezu et al. (2014) reported that, pertaining to poor management of mango production, thrips, fruit flies, termites, and various fungal diseases constrain the crop in ethiopia. white mango scale is a noxious pest which has been reported to affect commercial values of mango in many countries (labuschagne et al., 1995; pena et al., 1998; nabil et al., 2012; mazzeo et al., 2014). in ethiopia, white mango scale was reported to have posed severe threat to mango production since its first record in 2010 (mohammed dawd et al., 2012). white mango scale is a phytophagous insect. it inserts its stylets in leaf, fruit and other young mango parts and sucks the sap and results in discolouration of the leaves and the fruits, brings about dieback of the tree and in severe cases causes total death of young mango trees (abo-shanab, 2012; juárez-hernández et al., 2014). various methods, such as cultural method, biological control and chemical insecticide applications have been implemented to control the damages inflicted by white mango scale to mango in different mango growing countries. in line with this, pruning as a cultural method, was practiced and found to have considerably decreased population of white mango scale in mexico (bautistarosales et al., 2013). regarding the possible role of bio agents in controlling the pest, ofgaa djirata et al. (2017) reported from a field experiment in ethiopia that larvae of predatory ladybird beetle were found aggressively preying on it, even though whether they could control the pest or not has not been reported so far. moreover, it was stated that ladybird beetles, and green lacewings and tiny parasitic wasps may be used to suppress scale insect populations (muralidharan, 1994; buss and turner, 2006). chemical insecticides and mineral oils such as deltametrine, pyrethrin, super masrona and diver were also proposed for the control of mango scales in egypt and kenya (findlay, 2003; abo-shanab, 2012). in ethiopia, however, there has been no sufficient report regarding insecticide efficacy test for control of white mango scale, for which this study was conducted with the core objective of evaluating the most effective insecticides that could help control the pest. 2. materials and methods 2.1. description of the study area this study was performed at arjo gudetu mango orchard (09° 03´n and 036° 17´e) found in diga district, east wollega administrative zone of oromia national regional state at a distance of 370 km west of addis ababa, from mid-may to end of july 2016. the area receives a mean annual rainfall of 1649 mm and characterized by maximum and minimum monthly temperatures of 31°c and 16°c, respectively (ethiomet, 2016).the orchard was found on a gentle slope with altitudes ranging between 1326 and 1379 m a.s.l. the study farm was entirely composed of local mango landraces grown by the orchard owner for the last 25 years. the plantation was spaced at an average distance of nine to ten metres away from each other. however, since no pruning has been practiced to the mango trees in the farm, most of the trees were tall and bushy, and moreover, their branches were highly interlocked in most instances. there has been no insecticide application to the mango farm for pest control so far (personal communication with fayissa dhuguma, owner of the orchard). the farming population of the study area grows mango as the major income generating crop next to maize and peanut. cattle fattening is another source of income in the area. 2.2. the experimental design the field experiment was laid in a randomised complete block design (rcbd) with three replications. allocation of each treatment and the untreated control within each replication was done randomly. in the meantime, three mango trees were allocated for each insecticide and to the untreated control. after the allocations, each mango tree assigned to each treatment and that of the untreated control were tagged accordingly for repetitive spray and response ofgaa djirata. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 88 record from the same tree. before application of the formulations, the volume of water enough to completely cover a mango tree was calibrated. mean volume of water enough per tree was found to be 20 litres. the mango trees being tall and bushy, telescopic extension lance of 3.2 meters long was fixed to the sprayer knapsack. spraying was effected with the spray man being supported by scaffold fixed on a tractor back for ease of accessing all parts of each mango tree. treatments were applied every 14 days for a total of three times. a total of ten leaves were plucked from top, middle and lower canopies of each treatment tree and the untreated control, one day prior to each treatment and on the 5th and the 10th days after each treatment. the leaves from each tree were placed in a separate cloth bag, labelled, kept in a plastic bag and taken to a temporary laboratory established around the trial area. live crawler, male and female white mango scales were counted by the use of stereo microscope and recorded as number of live white mango scale. 2.3. insecticides evaluated field experiment was carried out to evaluate efficacy of three insecticides against white mango scale. these were closer 240 sc (sulfoxaflor), d-c-tron (mineral oil) and folimat 500sl. closer 240 sc (sulfoxaflor) was registered for the control of cabbage aphids on cabbage in ethiopia (federal democratic republic of ethiopia ministry of agriculture and natural resources, 2016). it was obtained from chemtex plc, addis ababa, ethiopia. closer 240 sc was applied with the rate of six ml/tree in this study. the remaining two candidates, dc-tron (mineral oil) and folimat 500sl (omethoate 500g/l or 47.5% m/m) were registered in kenya (pest control product board, 2016). d-c-tron plus was used for the control of leaf miners and scales in coffee, mites and aphids in flower and aphids in beans in kenya. it was bought from caltex oil (k) ltd, nairobi-kenya and imported to ethiopia for the purpose of this evaluation only. d-c-tron plus was applied with the rate of 100ml/tree in this study. folimat 500sl was used for the control of aphids on coffee, citrus and flowers, and mealy bugs on coffee in kenya. like d-c-tron plus, folimat 500sl was also bought from a legal company known as arysta lifescience corporation (k) in nairobi, kenya, and imported to ethiopia for the purpose of screening in this study. folimat 500sl was applied at the rate of 25ml/tree in this study. closer 240 is systemic in its action but folimat serves as both systemic and contact insecticidal agent. d-c-tron plus is, however, suffocant oil. 2.4. data analysis sum of live crawler, female and male white mango scale was taken as white mango scale count data and subjected to analysis. proc anova of sas software v9 was applied for data analysis. significant means were separated by fisher’s least significant difference (lsd) at 5% error level. percentage reduction in white mango scale population over control was worked out after each treatment using henderson and tilton (1955) formula of mortality correction. mortality correction = (1 − n1 ∗ n2 n3 ∗ n4 ) ∗ 100 where, n1, n2, n3 and n4 are white mango scale populations in control before treatment, in treated after treatment, in control after treatment and in treated before treatment, respectively. 3. results mean numbers of white mango scale counts per 10 leaves just before the initial treatment and in the two successive records following the first treatment are shown in table 1. table 1: white mango scale population counts before insecticide application and during the two successive recordings after initial application treatment/control record before initial spray first record after initial spray second record after initial spray d-c-tron 297 300 298 closer 333 330 320 folimat 1084 1070 1066 control 155 157 158 ofgaa djirata. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 89 noticeable declines were observed in the counts of live white mango scale among the records starting from post second spray, mainly for closer and folimat, while population build up was recorded in cases of the untreated control. mean numbers of live white mango scale per 10 leaves from pre-second spray onward are indicated by the following figures (figures 1and 2). figure1: white mango scale populations just before and after second round insecticide application figure 2: white mango scale population just before and after third round insecticide spray the result of evaluating the three insecticides revealed that folimat (49.52 ± 15.74) was found to be the most effective insecticide in reducing the population of white mango scale on mango with significant different (p0.05) compared to closer (18.72 ± 5.32) and d-c-tron (5.90 ± 2.15) at 5% error level (lsd=29.15). in the course of recording live white mango scales following each treatment, dead bodies of non-target insects, including chilocorus sp. larvae (coleopteran) were frequently encountered on mango leaves treated with folimat, while no dead body of those insects was found on the leaves treated with the rest two insecticides, in most observed cases. percent corrected mortality showed marked progress from the first to the third application of the insecticides, mainly in folimat and closer. reduction in white mango scale population in response to the insecticides applied during the three phases (a and b for first and second responses after initial spray, c and d for first and second responses after second round spray, and e and f denoting first and second responses after the third round (final) spray, respectively) is shown in figure 3. figure 3. white mango scale percentage reduction in response to successive treatments 4. discussion population count started to noticeably decrease only after the second round spray in folimat and closer treatments. this is probably because as the mango trees under the experiment were tall, bushy and characterized by dense foliage, there might be some probabilities of uncertainties to have fully addressed each mango scale through only one round spray. chin et al. (2010) underlines that keeping mango tree sizes at a manageable stature through pruning is very essential for ease of insecticide spray for the desired response in the control of pests and diseases. reddy et al. (2018) also states that pruning is an essential management practice in the control of scale insect infestation on mango. on the other hand, the apparent population decrease following repeated applications of the insecticides might account for cumulative effects of the successive sprays. the principle of applying systemic insecticide to control sucking insects arises from the fact that they diffuse through the soft parts of the host plant and reach the pest. therefore, the rate at which it gets in contact with the pest may not be as fast as contact insecticides. gashawbeza ayalew et al. (2015) screened methidathion ofgaa djirata. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 90 and movento on white mango scale on mango trees in central rift valley, ethiopia and found that population counts after the first treatment were similar between the treatments but differences were observed after the second spray, a report in agreement with the current trial. population build-up was observed in the untreated control, indicating that the period of insecticide application in this trial took place during the period of continuous growth of white mango scale population. ofgaa djirata et al. (2018) stated that white mango scale population on mango began to build from february and attained its peak sometime before july. folimat 500sl was found to exhibit over 90% pest population reduction with marked difference from closer 240, which also performed well. it was reported that mango farmers in central and eastern kenya were using this product to have controlled white mango scale (ofgaa djirata, et al., 2016). folimat is both systemic and contact insecticide. the white mango scale first instars are naked and as a result folimat can exterminate them upon contact, which could probably increase its efficacy in addition to its indirect action on the armoured adult scales which are sap sucking. non-target insects were found dead on leaves treated particularly with folimat. this probably demonstrates its strong toxicity which renders it worrisome profile to be considered for white mango scale control in the context of this study. however, whether the death of the non-target insects was purely due to folimat had not been evaluated in this study. it was indicated that folimat serves as both systemic and contact insecticidal agent while closer 240 works only by translaminar and systemic activity. therefore, it is arguable that closer 240 could cause similar deaths of nontarget insects, which were particularly not sucking insects. 5. conclusion folimat was found to exhibit considerable efficacy in reducing white mango scale population on mango. however, such highly toxic insecticides should not be used for white mango scale control purposes from ecological concern points of view. complete coverage of the indigenous tall and bushy mango trees with insecticide during the spray was almost impossible. it is concluded, therefore, that controlling white mango scale on big mango trees by manual spraying, mainly at small scale farmer level after heavy infestation is highly challenging. as a result, it is advisable to practice consistent pruning and maintain general stature of the plantation at manageable size and make integrated pest management an integral component in the control of white mango scale infestation on mango. acknowledgment mr. fayissa dhuguma, the owner of gudetu arjo mango orchard has allowed me to use his farm for this study and supported the investigation through providing his tractor with fuel throughout the study period and hence deserves due acknowledgement. i thank chemtex plc insecticide supplier plc and mr. yemenu jembere, general manger of the plc; and mr. yordanose ameyu, agronomist of the plc, for the material, logistic and professional supports they gave me during this study. i would thank professor emana getu for the technical support he gave me in the course of this study. reference abo-shanab, a.s.h. 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(2006). importation of fresh mango fruit (mangifera indica l.) from india into the continental united states: a qualitative, pathway-initiated pest risk assessment. raleigh: center for plant health science and technology, plant epidemiology and risk analysis laboratory. wauthoz, n., balde, a., balde, e.s., damme, m.v. & duez, p. (2007). ethnopharmacology of mangifera indica l. bark and pharmacological studies of its main c-glucosylxanthone, mangiferin. international journal of biomedical and pharmaceutical sciences, 1:112-119. wiersinga, r.c. & jager, a.d. (2009). business opportunities in the ethiopian fruit and vegetable sector. wageningen: report 2008 075.lei. yilma tewodros (2009). united nations conference on trade and development expert meeting of ldcs in preparation for the 4th united nations conference on the least developed countries: case study on ethiopia: united nations conference on trade and development. 94 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper corpus-based word sense disambiguation for ge’ez language amlakie aschale alemu1,, kinde anlay fante2 1department of electrical and computer engineering, faculty of technology, debre tabor university, debre tabor, ethiopia 2faculty of electrical and computer engineering, jimma institute of technology, jimma university, jimma, ethiopia article info abstract article history: received 20 august 2020 received in revised form 08 december 2020 accepted 24 december 2020 in natural language processing, languages have a number of ambiguous words. the absence of automatic word sense disambiguation for any language can be a challenge for the development of natural language processing applications such as information extraction, information retrieval, machine translation, etc. the aim of this study is to design a word sense disambiguation prototype model for ge’ez language words using corpus-based techniques. due to the unavailability of ge’ez wordnet and annotated datasets, six ambiguous words were chosen for this study. these words are ሀለፈ (halafe), ቆመ (ḱome), ባረከ (bareke), አስተርዓየ (astaraye), ገብረ (gebre), ሰዓለ (se’ale). a total of 2119 ge’ez sense examples were collected for the six ambiguous word from ge’ez literature. the performance of three corpus-based machine learning techniques (adaboost, smo, and adtree) were tested on the weka package. we evaluated the performance of the three corpus-based machine learning approaches which are unsupervised, supervised and semi-supervised for disambiguation of the six ge’ez words. the experimental results show that the best performance is achieved using adtree algorithm (semi-supervised machine learning approach). the proposed method achieved an average performance of 92.1%, 91.3%, 91% and 91.1% of precision, recall, f1score and accuracy using adtree algorithm respectively. a window size of 4-4 has been found to be the optimal window size to identify the meaning of the selected ambiguous words of ge’ez language using adtree algorithm. keywords: natural language processing word sense disambiguation semi¬-supervised adtree ge’ez language 1. introduction in the 21 st century, the growth of information technology has led the way for a large volume of information to be available for the society. discussion about importance of a language for using the available information is not far from obvious since it serves as a medium of communication among the races. language has a potential to express a wide range of ideas and to convey complex thoughts. in particular, natural language is now being used to exchange information among humans and has now reached to the extent of being evolution criteria for the technology. in order to  corresponding author, e-mail: amlakieaschale19@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.283 make available information useful for the society, an interest has emerged to make use of technology to process natural language. in response to such a need, natural language processing (nlp) has come up with a main focus of natural language computations (getahun wassie and million meshesha, 2014). nlp is a field of computer science that deals with the interaction among computers and humans using natural language that aims to enhance human-to-human communication and human to computer communication (solomon mekonnen, 2010). it is normally used to describe the function of software or hardware http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021.............. amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 95 components in a computer system, which analyzes or synthesizes spoken or written language. there are in fact two distinct focuses of nlp: language processing and language generation. the former one refers to the analysis of language for producing a meaningful representation, while the second refers to the production of language from a representation (pal et al., 2013). the field of nlp was originally referred to as natural language understanding (nlu) in the early days of artificial intelligence. it is well agreed today that while the goal of nlp is true nlu, that goal has not yet been accomplished. a full nlu system would be able to paraphrase an input text, translate the text into another language, answer questions about the contents of the text and draw inferences from the text (mahmoodvand and hourali, 2017). the aim of nlp is studying problems in the automatic generation and understanding of natural languages. natural language is understood as a tool that people use to express themselves and has specific properties that improves the efficiency of textual information retrieval systems. these properties are linguistic variation and ambiguity. nlp is also a subfield of artificial intelligence and linguistics (naseer and hussain, 2009). ambiguity is one of the greatest challenges in nlp, the term refers to understanding of something in two or more possible ways or something that has more than one meaning. it can appear in sentence (called structural or syntactic ambiguity) or at a word level (called lexical ambiguity) and phonological ambiguity. ambiguity is a universally recognized linguistic phenomenon, which arises from the structure of the language and can be explained in terms of the analysis at different levels (daniel jurafsky, 2018). so that developing word sense disambiguation (wsd) is crucial for the development of natural language applications such as information extraction, machine translation, information retrieval, question answering, text summarization and others. in the field of computational linguistics, word sense disambiguation is defined as the problem of computationally determining which “sense” of a word is activated by the use of the word in a particular context. lexical disambiguation in its broadest definition is nothing less than determining the meaning of every word in context, which appears to be a largely unconscious process in people. due to the importance of wsd for understanding semantics and many realworld applications, researchers have been interestingly trying to tackle that problem. so far, different word sense ambiguation techniques were proposed for amharic (getahun and million, 2014; seid and yaregal, 2017; solomon mekonnen, 2010), afan oromo (workneh tesema et al., 2016), and tigrigna (mersa mebrhatu, 2018) as languages of ethiopia. to the best of our knowledge, there is no word sense disambiguation model reported for ge’ez language. the objective of this work was to develop a word sense disambiguation model for six ambiguous ge’ez words. we have designed three different corpusbased machine learning models to compare the performance of different techniques. through experiment, we have explored the best model and the parameters of the models for six ambiguous ge’ez words. 2. materials and methods this section describes the design of wsd system for ge’ez language. it mainly focuses on preparation of corpus, word selection, architecture of ge’ez wsd model, document preprocessing techniques, preparing machine readable datasets, and evaluation techniques of the model. according to different scholars, words that we want to disambiguate could be selected by the researchers from wordnet, which is available on the web or online, or from different sources of the language or documents of the language, which is annotated manually. 2.1. wordnet wordnet is a lexical database; it provides a large repository of some languages lexical items, which is available online. the wordnet was designed to establish relations between the main four types of parts of speech (pos): noun, verb, adjective and adverb. wordnet defines the relations between synsets and relations between word senses. a specific meaning of one word under one type of pos is called a sense and synset represents the smallest unit in wordnet, which describes a specific meaning of a word. it includes the word itself, explanation and the synonyms of its meaning. the difference is that lexical relations are relations between members of two different synsets, however semantic amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 96 relations are relations between two whole synsets (workneh tesema et al., 2016). 2.2. words that are selected from documents according to mersa mebrhatu, (2018), the construction of the sense tagged corpus needs a great amount of time and cost. due to this reason, we have selected small a number of ambiguous words in this study. the corpora which have sense information of all words, have been built recently, but they are not large enough to provide sufficient disambiguation information of the all words. therefore, the methods based on the sense tagged corpora have difficulties in disambiguating senses of all words so that the selection of ambiguous words that were used in this study was based on the number of senses of single word. in leykun berhanu (2005), there are words that have multiple senses, from two sense up to sixteen sense. due to the unavailability of ge’ez wordnet and annotated datasets, six ambiguous words that have two senses were chosen for this study. these ambiguous words are selected from ግስ (gis) which is found in ቅኔ (kinie) school in ethiopian orthodox tewahido church. wsd performance can be affected by the distribution of training data for each sense that means number of sense examples are required to be equal as much as possible and a balanced distribution of training data has been employed to maximize performance in the work of (solomon mekonnen, 2010). 2.3. data collection in this research, we have used corpus-based approach. it is challenging to acquire sense annotated corpus for wsd studies due to lack of standard sense annotated corpus or context-based repository (wordnets) for ge’ez language. due to this reason, data collection becomes first rather than corpus preparation. by considering this, the researchers collected data from different sources such as ge’ez bible, sinksar, fithanegest, gedile semaetat, and teaching materials from bahir dar university ge’ez department. here, we first collected a huge data that contains 193,000 sentences or instances. to retrieve the sentences that contain the selected ambiguous words; we developed a simple algorithm and this simple algorithm accepts a word which is an ambiguous words from the user and then displays the sentences that contain the given ambiguous word and we have got 2,119 sentences or instances from a huge data that we collected. according to yemane kaleta et al. (2016), selecting sentences of ambiguous words from a variety of domains is very important to build efficient and reliable wsd prototype since similar domains usually restrict words to one sense. therefore, in order to build efficient and reliable wsd prototype for ge’ez language, we collected data from different domain areas. 2.4. proposed system architecture the flow of activities that are used to develop the proposed wsd is given in figure 1. the proposed system architecture contains different steps. the first step is accepting sentences that contains ambiguous words. the next step is applying preprocessing activities like normalization, tokenization, stop word removal, stemming and transliteration. in unsupervised learning, unlabeld datasets are given to the selected clustering algorithms to build wsd prototype model of ge’ez language. whereas, in supervised learning labeled datasets are given to the selected classification algorithms to build wsd prototype model of ge’ez language. in semisupervised learning, a few numbers of labeled seed examples together with large number of unlabeled datatasets are given to the selected clustering algorithms inorder to obtain fully labeled datasets based on labeled seed examples. those fully labeled datasets are given to the selected classification algorithms to build wsd prototype model of the language. 2.4.1. preprocessing phase p reprocessing describes any type of processing performed on raw data to prepare it for next processing procedure. hence, preprocessing is the preliminary step which transforms the data into a format that will be more easily and effectively processed. preprocessing must ensure that the source text be presented to nlp is in a form usable for it. in this study, preprocessing is a primary step to make our data sets compatible with the machine learning tool that was used in our study called weka. in the preprocessing stage of this study tokenization, stemming, stop word removal, transliteration and normalization are performed. amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 97 figure 1: corpus-based ge’ez wsd system architecture 2.4.1.1. normalization: in this study, normalizing the characters is performed because it is not suitable for the next preprocessing stages. in ge’ez writing system, characters with the same sound have different symbols. these different symbols must be considered as similar even if they have effect on meaning. as a result, in this study, some symbols of the same sound were converted to one common form. for example, if the character is one of ዐ,ኣ,ዓ (with the sound a) then it will be changed to their equivalent respective orders of አ, similarly, ሐ,ሓ,ሃ,ኀ and ኃ (all of them with a similar sound, h) then it will be converted to ሀ to make ሀለፈ. by the same token, all orders of ሠ (with the sound s) are changed to their equivalent respective orders of ሰ to make ሰአለ. generally, we normalize the characters based on the words that we have selected in our study but not for all ge’ez language words. 2.4.1.2. tokenization: tokenization is very important to this study. it is the process of breaking sentences into words or tokens. the corpus, which is a set of sentences first tokenized into words. tokenization is done by identifying with the white spaces, comma (,) and special symbols between the words. all punctuation marks, numbers and special characters are removed from the text before the data is processed. hence, these punctuation marks don’t have any relevance to identify the meaning of ambigous words using wsd. therefore except '።' which is used to detect the end of the sentence, all other punctuations are detached from words in tokenization process. tokenization is used to get context words for disambiguation purpose. for instance, if we have a sentence like ወተርፈ : አዳም : ውስተ : ምድረ : ኤዶም : ወቃየንሰ : ሀለፈ : ወሀደረ : ታህተ : ምስራቀ : ኤዶም።, then tokenized sentence will be ወተርፈ, አዳም, ውስተ, ምድረ, ኤዶም, ወቃየንሰ, ሀለፈ, ወሀደረ, ታህተ, ምስራቀ, ኤዶም, ። 2.4.1.3. stop word removal: after tokenization, we have removed ge’ez language stop words, as it has no effect on meaning of the words. in this study, stop word removal is used to remove stop words from the corpus because the absence or presence of these words has no contribution to identify appropriate sense. not all tokenized words are necessary in this work. for this study, we collected stop words which are conjunctions, prepositions and articles of the language because of absence of standard stop words. for instance, words such as (‘ባህቱ’, ‘እንተ’, ‘ከማሁ’, ‘ኩሉ’, ‘እምዛ’,’እስመ’, ‘ድህረ’, ‘እምነ’). since stop words do not have significant discriminating powers in the meaning of ambiguous amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 98 words; we filtered stop­words list to ensure that only content bearing words are included. nevertheless, stop words like ‘ሀበ’ and ‘መንገለ’ are not removed from the corpus because they have a significant role on the word ‘ሀለፈ’. 2.4.1.4. stemming: stemming is the process of reducing morphological variants of words into base or root form. in morphologically rich languages like ge’ez, a stemmer will lead to significant improvements in wsd systems. in ge’ez language, there are different terms that are generated from the same root word due to their grammatical use. to create different derivational and inflectional word forms, ge’ez language makes use of prefixes, suffixes, and infixes. therefore, those extra words or characters that change the root word to different forms are stemmed from the corpus using the stemming algorithm developed by ourselves which is suitable for the language. this algorithm removes both prefixes and suffixes only since we developed affix removal of the stemmer. therefore, to get the common form of the ambiguous words we tried to normalize infixes of the root word manually. for example, an ambiguous word ‘ገብረ’ may become like ‘ገብሩ’, ‘ይገብር’, ‘ይግበር’, etc. after removing both prefixes and suffixes. to make it suitable for machine learning algorithms, we inspected manually all those words into one word which is‘ገብረ’. the same thing was applied for other ambiguous words that are used in this study but not for the context words. the reason behind not applying normalization after stemming for the context words is due to the long time it takes to normalize all the context words that are used in this study. 2.4.2. transliteration after the above preprocessing tasks were done for ge’ez documents that we have collected; transliteration were performed for ge’ez language documents. it is the representation of the characters of one language by corresponding characters of another language. in this study, the transliteration was accomplished from ge’ez characters into latin characters to make documents compatible with the machine learning tool called weka (getahun wassie and million meshesha, 2014). since we selected a machine learning tool (called weka) for conducting our experiment, we applied transliteration because weka platform uses attribute relation file format (arff) or comma separated value (csv). these file formats can be applied after transliteration have been performed in order to make it compatible with the weka tool. the transliteration of the ge’ez corpus was conducted by using system for ethiopic representation in ascii (sera). 2.5. preparing datasets in this study, we used corpus based approach. we prepared a combination of labeled datasets for supervised learning, unlabeled datasets for unsupervised learning and semi-labeled datasets semi-supervised for training. because corpus-based approach uses both labeled and unlabeled datasets for training and testing. more number of sentences need not be annotated manually in semi supervised machine learning approach. instead of this, we select the representative seed examples for each sense of ambiguous words. so to select representative seed examples, labeled and unlabeled data size distribution for training set is typically 85­98% unlabeled datasets; and the rest are for labeled datasets (mahmoodvand and hourali, 2017). according to this, we prepared 12% of labeled datasets and 88% of unlabeled datasets for each of the six chosen ambiguous words from the total datasets before clustering. that means a word ‘ገብረ’ has 160 instances, so from this 12% are labeled and 88% are unlableled which becomes 20 instances are labeled and 140 instances are unlabled. when we label seed examples automatically, we applied the following techniques. 2.5.1. seed selection techniques in this section, the techniques that were applied in this study will be presented. this research was conducted by using corpus based approach. both labeled and unlabeled documents were used in the semi-supervised approach. the seed selection technique employs the method proposed in (getahun wassie and million meshesha, 2014). the techniques that were used in this study consist of four steps. step 1. selecting representative seed examples for each class or sense of the ambiguous words: selecting representative seed examples for each class is effective and those selected seed words are used to label unlabeled documents. selecting seed words to select representative seed examples for semi-supervised approach is challenging task (getahun wassie and million meshesha, amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 99 2014). selecting improper seed examples results in poor performance. improper seed examples can be selected when we tag (label) our datasets randomly by humans. when humans select seed examples randomly, they may select improper seed words which means the selected seed words cannot differentiate the senses (meanings) of the ambiguous word. to minimize manual selection of limited number of seed examples from the total datasets, we used tree algorithms because tree algorithms represent the related concept of the target word starting from the node. tree algorithms use information gain as lexical knowledge and information gain can minimize subjectivity problem in manual selection of seed examples (solomon mekonnen, 2010). by considering this concept, we used adtree algorithm to select seed words. we classified our datasets by using adtree algorithm for each ambiguous words and then tree visualization is performed. after tree visualization, we took seed words scoring high information gain in the tree structure. those seed words were used for discrimination purpose of the remaining sense of the ambiguous word. step 2. clustering both labeled and unlabeled seed examples using “classes to clusters evaluation” mode: here, we have not used the resulting clusters from the adtree algorithm for classification. we only use them to identify the cluster of missing instances based on labeled seed examples. after clustering have been done using em algorithm which has best performance in clustering algorithms in this study, we can see the effect of semi-supervised learning method in our work. the clustering result shows that the class labels of some of the seed examples were misclassified. however, automatic clustering suggests that such label changes were not required because those seeds were labeled with their sense class as the promise they are chosen by experts intentionally. step 3. feature extraction and selection: feature selection: the success of machine learning requires instances to be represented using an effective set of features that are correlated with the categories of word senses. for this study, feature selection was performed by preparing a eight-eight window size. because in our datasets the highest window size is eight. instances with missing values were also removed from the feature sets. therefore, feature selection is a data reduction mechanism. feature extraction: feature vector which represents words for each instance of a target word, that means files of comma-separated values, a line in weka with an extension of. arff or .csv. these vectors represent a text window surrounding ambiguous word of a eight-eight words in our case. step 4. design of the classifier: before classifying our datasets using the selected classification algorithms, we labeled our datasets manually depending on the selected seed words. the manually labeled seed examples being are used as cluster labels during clustering of both labeled and unlabeled documents (datasets). knowing cluster label of each instance becomes important for differentiating the class of missed instances by taking each cluster as a distinctive class. this helps us to label unlabeled instances with their classes. table 1: example of wsd dataset for semi-supervised learning lcontext3 lcontext2 lcontext1 target word rcontext1 rcontext2 rcontext3 class ? ? emeze halefe kaeba bahere horu pass ? tanesio emeheya halefe halafa behera tirose pass halifo kaeba tirose halefe wosidona galila maekala pass ? tanesio emeheya halefe haba behera yehuda ? reeyo soba maseya halefe haba bitaneya aseretu ? ahadu aseretu keleetu halefe haba liqana kahenate died maseyo halafa aseretu halefe aseretu keleetu aredaihu died ? ? sanita halefe hagara nayene horu ? ? ? emeze halefe soba baseha gize ? ahadu beesi kebure halefe behera rehuqa yenesae ? ? represents missing value amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 100 table 1 indicates that we prepared our datasets with 18 attributes and two of them are target word and class. the rest 16 attributes are context words that are used to determine the meaning of the ambiguous word which means eight words to the left and eight words to the right of the target word. attributes that exceeds this size are removed. when we use eight words to the left and eight words to the right, there might be missing values. those missing values are replaced by question marks (?), because question mark is compatible with weka. reducing dimensionality of datasets can improve the performance of wsd; because instances having redundancy and missing values problems will be reduced (solomon mekonnen, 2010). 2.6. evaluation techniques to evaluate performance of clustering and classification algorithms, four different modes are available in weka. those are using training sets, supplied test set, percentage split, classes to clusters evaluation mode and cross validation for both clustering and classification algorithms. however, when we train and test our datasets on all the above evaluation modes, classes to clusters evaluation mode and cross validation are the most effective evaluation modes. therefore, for our study we used ‘classes to clusters evaluation’ mode for clustering algorithm and cross validation for classification algorithm. therefore, for this study we used ‘classes to clusters evaluation’ mode for clustering algorithm and cross validation for classification algorithm. when we use ‘classes to cluster evaluation’ mode, weka shows the clustering result as error rate using ‘classes to clusters evaluation’ mode. therefore, accuracy of clustering algorithms was obtained after subtracting the error rate from hundred. this accuracy is used to measure how well it has been able to generalize the clustering results. for this study 10-fold cross-validation evaluation technique is used in our experiment. in this technique, first the total data set is divided into 10 mutually disjoint folds approximately of equal size using stratified sampling mechanism. in stratified sampling, the folds are stratified so that the class distribution of the tuples in each fold is approximately the same as that in the initial data. we have a total of 2119 manually tagged sense examples which is divided into 10 approximately of equal sizes. as a result of this, each fold of a data set contains 212 sense examples with balanced distribution number of senses per fold. after identifing and separating the training set and testing set from the total datasets, we remove manually tagged sense examples from test set. during this process 90% of the data is used for training to develop the system whereas the remaining 10% is used for testing the system. the process was repeated ten times. after each training phase, the system was tested on average of 212 ge’ez sentence. each of the corresponding training set contains an average of 1907 sentences. the performance of classification algorithms is usually measured by parameters such as accuracy, recall, precision and f-measure. these performance parameters are the functions of the numbers of correctly and incorrectly classified instances which are obtained on the confusion matrix of weka output. 3. results and discussions this section presents the performance evaluation of the implemented model. to achieve our objectives, the following experiments or scenarios are considered which are applied on our prepared datasets.  comparison of corpus based approaches which are supervised, semi-supervised and un-supervised with different modes;  investigating the most effective approach and effective algorithm from the selected algorithms that improve the performance of ge’ez wsd model;  experimenting with different context window size for disambiguation of ambiguous words. 3.1. comparison of corpus based approaches to compare results of unsupervised, supervised, and semi­supervised machine learning approaches; we used the same datasets of the language, and the classification algorithms for both semi-supervised and supervised approaches. but in study (solomon mekonnen, 2010) for unsupervised approach we used the selected clustering algorithms which are expectation maximization, simple k-means, farthest first, hierarchical clusterer for clustering purpose of our datasets. we used clustering algorithms for un-supervised machine learning approach because clustering is unsupervised technique. therefore, comparison of those three machine learning approaches was conducted on the same datasets. in addition to this, comparison of semi-supervised and supervised approaches amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 101 was conducted on the same datasets by using the same classification algorithms. the algorithms are smo, naïve bayes and bagging which are supervised learning methods, and adaboost and adtree are used from semi-supervised learning approach. 3.1.1. unsupervised learning unsupervised learning is an independent process where no supervision is involved during the learning step. unsupervised corpus based methods do not rely on external knowledge sources such as mrd, concept hierarchies and sense tagged texts. those approaches are mainly clustering approaches where words and contexts are clustered. during clustering, each cluster corresponds to a sense of a target word. the goal of clustering is to group together elements in a way which maximizes similarity between elements in one cluster and to minimize similarity between elements belonging to different clusters. 3.1.2. supervised learning supervised is the use of algorithms that reason from externally supplied instances (training set) to form classes to differentiate new data. the goal of supervised learning is to build a model of the distribution of class labels in terms of predictor features. in order to build the model it involves training and testing phases. during the training phase a sense-annotated training corpus is required, from which syntactic and semantic features are extracted to build a classifier using machine learning techniques and in testing phase the classifier tries to find out the appropriate sense for the word based on surrounding words present in the instances. 3.1.3. semi-supervised learning semi-supervised techniques involve training information like in supervised but the information given at initial training phase is less. semi-supervised or minimally supervised methods are gaining popularity because of their ability to get by with only a small amount of annotated reference data while often outperforming totally unsupervised methods on large data sets. there are a host of diverse methods and approaches, which learn important characteristics from auxiliary data and cluster or annotated data using acquired information. for comparison purpose, we can take the maximum average performance or accuracy of the three machine learning approaches by using their best performing algorithms since they record best accuracy for all unsupervised, supervised and semi-supervised methods.the result is shown in figure 2. from figure 2, we can observe that semi-supervised machine learning approach achieves the highest accuracy of wsd prototype models. by using both labeled and unlabeled datasets, the performance of wsd prototype model have improved compared with other approaches. this is because unlabeled datasets are clustered using manually labeled datasets during clustering. from this we can see that semi-supervised machine learning methods are figure 2: average performance of the three-machine learning approaches amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 102 the most suitable methods for the development of ge’ez wsd prototype model than supervised and un-supervised machine learning methods using bootstrapping, which means using adtree, adaboostm1 and smo algorithms. we achieved the best performance of the classifier for ge’ez ambiguous words using semi-supervised corpus based approach, because seed words which are obtained with high information gain using adtree algorithm were used for the selection of representative seed examples of this study. 3.2. comparison of classification algorithm for ge’ez datasets for investigating the best performing classification and clustering algorithm for ge’ez wsd prototype model, we applied three approaches namely unsupervised, supervised and semi-supervised approaches for the selected six ambiguous words of ge’ez language. we used the result achieved by using semi-supervised methods because the performances achieved by using those machine learning method were the most preferable when we compared with the performances achieved by unsupervised and supervised learning methods. for investigation purpose of those selected semi-supervised algorithms, we used average accuracy, precision, recall and f1-score to access the performance of the three machine learning algorithms. the comparison of those three classifying algorithms was based on the achieved performance to classify ambiguous words of ge’ez language. those performance comparison of the selected classification algorithms was done on the same ge’ez dataset. the result is shown in figure 3. from figure 3, we observe that adtree algorithm achieves the best performance for our datasets. we achieved an average precision, recall, f1-score and accuracy of 92.1%, 91.3%, 91% and 91.1%, respectively. its efficiency was also better than adaboostm1 and smo algorithm. adaboostm1 and smo algorithms also performed comparable result to each other for ge’ez wsd prototype model. 3.3. determining the optimal context window size of the language to find the optimal context window size, different studies have been conducted using different wsd approaches for different languages. wsd researches were conducted for amharic language by different researchers starting from one-one to ten-ten window sizes to find out the optimal context window size for this language using different approaches (solomon mekonnen, 2010). in a research conducted for amharic language using supervised machine learning method for five ambiguous words (mesasat, metrat, qerese, atena and mesal) and it was advised that window size 3-3 is an effective by using naïve bayes algorithm. the authors of (getahun wassie and million meshesha, 2014) have done a research on amharic wsd using semi-supervised machine learning method and advised that the optimal window size is 2-2 or 3-3 window size using five classification algorithms for the selected five ambiguous words of the language (atena, derese, tenesa, ale, bela). figure 3: performance of the classification algorithm amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 103 figure 4: average accuracy of each window size using semi-supervised approach algorithms the optimal window size 3-3 was effective for three of the bootstrapping and svm algorithms (adtree, adaboostm1, bagging, and smo), and 2-2 window size was reported to be effective using naïve bayes algorithm. due to those reason we used semi-supervised algorithms to determine the size of context window because semi-supervised approach scores the highest accuracy than the others approaches. we obtained that window size of 4-4 is the optimal window size in order to differentiate the meaning of the selected ge’ez ambiguous words using adaboostm1 algorithm in our study. from figure 4, we concluded that, semi-supervised algorithms perform much better than the other algorithms which means bootstrapping algorithms (adtree, and adaboostm1) svm algorithm (smo). we see that adtree, adaboostm1 and smo achieved high performance on the given datasets. however, our focus is to determine which window size is suitable for ge’ez language. then all algorithms that are adtree, adaboostm1 and smo score high accuracy on window size of 4-4. therefore, window size 4-4 is the best window size using adtree algorithm for our ge’ez datasets. smo was also the best performer algorithm next to adtree algorithm for window size of 4-4 using semi-supervised learning method. lastly, we can conclude that window size of 4-4 becomes best performer using adtree algorithm for wsd prototype model of our ge’ez datasets depending on our experiments. 4. conclusion and recommendations 4.1. conclusion there are so many words with more than one meaning in natural language and the meaning is determined by its context. the automated process of recognizing word senses in context is known as word sense disambiguation (wsd). in this study, three experiments have been conducted using different classification and clustering algorithms. the first experiment was a comparison of the results obtained using the three machine learning methods which means unsupervised, semi-supervised, and supervised learning methods. in this experiment, a semi-supervised approach has performed better compared to the other machine learning methods. since the semi-supervised learning method was employed in this work, we used the final fully labeled dataset which is obtained from unlabeled data sets. those unlabeled datasets were labeled after clustering using the clustering assumption. but for clustering purposes, we used the em algorithm because the em algorithm performs better compared to the other selected clustering algorithms. the second experiment was conducted to determine the best performing algorithm for the selected ge’ez datasets. from this end the best amlakie aschale and kinde anlay ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 104 performing algorithm for the selected ge’ez datasets were found to be the adtree algorithm compared to both clustering and classification algorithms that were selected in this study. the last experiment was conducted to investigate the optimal window size for determining the senses of each ambiguous word. from experimental results, we obtained that the window size of 4-4 can be considered as optimal window size for ge’ez wsd systems. in general, we conclude that semi-supervised learning is potential learning method that performs better in our study. there are many potential algorithms to be applied for ge’ez wsd systems using semi-supervised learning corpus-based approaches and adtree is the best performing algorithm for this language among those semi-supervised algorithms. 4.2. recommendations word sense disambiguation researches require a variety of linguistic resources like thesaurus, wordnet, machine-readable dictionaries and effective ge’ez language stemmer. there is no standard stop word of the language in which we faced a significant challenge as ge’ez lacks those resources. lack of sense annotated data for the language was also another challenge that makes us to limit our study on six ambiguous words of the language. and this makes us to limit our dataset on 2119 sentences or instances only. therefore, we have the following recommendations which include the development of resources and future research directions for wsd of ge’ez language:  this study considers words that have only two senses. in the futures, the researcher will consider words with more than two senses.  this study has concentrated only on modeling wsd to tackle lexical ambiguity which is at word level. further researches would be recommended to address other types of ambiguities in ge’ez language like character and structural ambiguity (sentsnces level).  in addition to the corpus-based approaches, there are also knowledge-based and hybrid approaches that were used for wsd of other languages. therefore, we recommend that these approaches need to be investigated for ge’ez language as well. referencec eker, ö. (2007). developing methods for word sense disambiguation. boğaziçi university. getahun wassie, ramesh, b. p., solomon teferra, & million meshesha. (2014). a word sense disambiguation model for amharic words using semi-supervised learning paradigm. science, technology and arts research journal, 3(3): 147155. jurafsky, d. (2000). speech & language processing. pearson education india. leykun berhanu(2005). contemporary challenges in the ministry of the ethiopian orthodox church. phd thesis, howard university. mahmoodvand, m., & hourali, m. (2017). semi-supervised approach for persian word sense disambiguation. in 2017 7th international conference on computer and knowledge engineering (iccke), 104-110. mersa mebrhatu (2018). unsupervised machine learning approach for tigrigna word sense disambiguation. computer engineering and intelligent systems, 9(6): 10–16. naseer, a., & hussain, s. (2009). supervised word sense disambiguation for urdu using bayesian classification. center for research in urdu language processing, lahore, pakistan. pal, a. r., kundu, a., singh, a., shekhar, r., & sinha, k. (2013). a hybrid approach to w ord sense disambiguation combining supervised and unsupervised learning. 4(4): 89–101. seid yesuf & yaregal assabie (2017). amharic word sense disambiguation using wordnet. in the 5th international conference on the advancement of science and technology. solomon mekonen. (2010). word sense disambiguation for amharic text: a machine learning approach. unpublished master’s thesis, 1-94. workneh tesema, tesfaye debela & kibebew teferi.(2016). towards the sense disambiguation of afan oromo words using hybrid approach (unsupervised machine learning and rule based). ethiopian journal of education and sciences, 12(1): 61-77. 65 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu review paper technological determinism versus social determinism: a critical discussion daniel tessema firrisa school of social science and humanity, adama science and technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 19 may 2020 received in revised form 26 march 2021 accepted 16 april 2021 technology influences the way human beings connect with the outside world in their day-today businesses. adopting new technologies can offer opportunities. it, also, poses threats. in the last many years it has been attempted to understand the very sophisticated relationship between society and technology. there is a belief that technology develops independently and that development in technology follows a somewhat linear order. putting an emphasis on sociocultural factors that have a role in technological development, some theorists become reluctant to claim that technology mainly determines society. the author of this paper is motivated to look at the issue of technology from philosophical perspective. thus, this paper is intended to critically discuss the philosophical theory of technological determinism against social determinism, the two conflicting schools of thought in philosophy, and then open a room for further investigation/debate by researchers. qualitative research method has been used. it used critical discussion as a tool. literatures in the topic have been used so as to make a relatively comprehensive discussion. the finding of the literatures reviewed shows that the debate between the two schools has no end. the paper contributes to showing the unsettled debate between the two schools and summarizes by recommending further investigation. keywords: autonomy ethics social constructivism social determinism technology technological determinism 1. introduction technology is a broad term that refers both to artifacts created by humans and the methods used to create those artifacts. technology is the process by which humans modify nature to meet their needs and wants. technology includes the entire infrastructure necessary for the design, manufacture, operation, and repair of technological artifacts. twentieth century is marked by technological progress, though the advancements in technology brought about unintended socio-environmental effects. the german philosopher hans (1979) gives emphasis to the need for anticipating and evaluating technology. for him, technology has impacts that extend in space and time. paul (2007) mentions hans’ argument as, “technological ethics must integrate science-based attempts to understand the corresponding author, e-mail: daniel.tessema@astu.edu.et https://doi.org/10.20372/ejssdastu:v8.i2.2021.250 systematic and distant effects of technology with ethical concepts attuned to the fact that many people who will be affected by technology will not be known to those who plan and implement a technological practice.”(paul, 2007). technology has actual and potential advantages to agriculture, medicine, the food industry, and the conservation of natural environment and many more. it needs to address several issues while assessing the benefits and risks associated with the introduction and application of new technologies. scientific and ethical issues are raised in relation to the development of technology. science describes the world in which we live in. on contrary, ethics deals with what we ought or ought not to do. thus, ethical principles tend to give http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i2.2021.250 daniel tessema ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 66 standards to evaluate a given action. it is difficult to separate the achievements of technology from that of ethics. ethics and technology are not only tightly coupled but also conflicting. an ethical understanding of the natural world is the basis for much of technological development today. conversely, technology is the basis for a good part of ethical research. both focus on the application of unique skills, knowledge, and techniques. different literatures have been reviewed to analyze the issue in question. the author used qualitative method to make a critical discussion on the topic. according to strauss and corbin (2008), qualitative research, which is inductive in its nature, allows a researcher explore meanings and insights about a certain discourse. moreover, as denzin and lincoln (1994) stated, “qualitative research is an interdisciplinary, trans-disciplinary, and sometimes counter-disciplinary field. it crosscuts the humanities and the social and physical sciences….” hence, this method allowed the author to connect physical science with humanity by critically discussing the two theories. discourse analysis is used while discussing the theories. 2. theoretical discussion during previous time, technology was assumed as an external force with deterministic influence on different dimensions of an organization. recent studies, however, come up with the human aspect of technology. as a result, technology becomes a subject of study having both positive and negative impacts on society. it is believed by sociologists or industrialists that technology lies at the center of society. what is technological determinism? the concept of technological determinism is defined by different scholars differently. technological determinism is a view which states that technology is an external force capable of shaping the society. in this regard, technological determinists hold the view that technology is self-governing and it is the sole cause for social change. however, there is an argument that technology also causes several problems. they see technology as a dominating force which poses physical or psychological threat to human beings. one example for supporting their evidence is the use of atomic bomb during the second world war. technology in this respect has an adverse effect upon the human race. concerning the role that technology plays, writers discuss three models. the technological imperative model sees the influence that a particular technology brings on such organizational properties as structure (hall, 1962). this model views technology as independent with greater influence on organizations as well as humans. the second model called strategic choice sees technology as a product of human action (child, 1972; mcloughlin, 1999). this model holds different perspectives in it. in the first place, we find the socio-technical perspective which focuses on how a certain technology is built on the basis of human choice and decision. it views technology as a dependent variable. second is the socio constructionist perspective. this school tries to emphasize on the meaning of a certain technology in terms of its creation and sustainability. the third perspective is that of marxian which states that technology is a tool to keep the economic as well as political interests of strong groups. according to this school, designers have the power to shape the technology while employees of an organization are endowed with little or no power to do so. for the third model called technology as a trigger for structural change, technology is perceived as interference. the relationship between organizational structure and human agency is intervened by technology. it is the stand of this school that the physical form of a given technology remains permanent even if its meaning might change overtime. the models discussed above are applicable in either similar or different situations. moreover, changes in society are implicitly or explicitly related to the advancement in technology. how is technological determinism then imaged? some discussion of technological determinism might create a pessimistic image while others optimistic. for example, according to ellul (1964), human beings become helpless unless technology supports them. for him, the rejection of a technique involves the application of a new technique. how could human freedom be controlled and oppressed by technology? ellul’s image towards technology looks harsh. determinism views everything as being determined by a mere sequence of earlier events that operate with predictability. technological determinism (td in short) daniel tessema ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 67 holds the view that technology is determined to develop in a particular pattern. it considers the historical development and autonomy of technology. determinism looks associated with the issue of free will. if everything is determined by previous conditions, then how could human beings owe enough choices? by the same token, technological determinism implies that human choices are controlled by technology. this view seems that it stands against human freedom and dignity. human beings have the freedom to influence technological direction. they direct, order and influence it. technological determinism is an influential theory of the relationship between society and technology. td tries to describe social and cultural phenomena in terms of a single determining factor. it was an american sociologist called veblen who coined the term (ellul, 1964). according to td, technology is seen as the mover of society. it is the main cause of social changes. it is technology which controls the pattern of social organization. technology is the foundation of society, according to technological determinists. they argue that it is technology which changes society and society is being determined by it. moreover, technology is capable of transforming society. that is why the proponents of this theory insist that technology is primary, followed by human factors. is society a product of technology or is technology a product of society? it is argued that technology gets separated from the influence of human beings. it is clear that technology has an impact on our lives. technological determinism holds the view that no technology is directed by man. rather, it follows its own course. moreover, technology is something outside of human control. technological determinism is aimed at dissociating humans from the role they play in the design and use of technology. though technologies mirror human values, they might bring undesirable effects. according to td, technological progress is inevitable. unlike td, social determinism views society as independent force which can alter technology (green, 2001). technological determinism has hard and soft forms (chandler, 1995). let me take a simple example to make this idea clear. if i say, “mobile phone will improve my life”, i mean that mobile phone, being a force, is dominant. it implies the hard form of td. but, if i say, “mobile phone will help me improve my life”, it means that there are other factors which determine my life. hence, i am using the soft form. the soft version of technological determinism holds the view that not only technological change derives social change, but also responds to social pressures. but, for hard technological determinism, development in technology is independent of social barriers. hard technological determinists argue that cause and effect relationships allow people to know with certainty about future consequences. some of them say that humans are not free to make choices. but, this view is against humanity. in my view, technology could not be the only determinant of change. it functions within a social structure. i argue that humans create technology. by so doing, they create their future. how could creations of their hands determine their destiny or future? for postman (a technological determinist), every use made of technology is determined by the structure of the technology itself. winner (a social determinist) comes up with a counter argument. for him what matters most is not the technology itself. rather, socio-economic systems, in which a technology is embedded, determine it. society controls technology. technology is shaped, for instance, through the influence of culture. to what degree is the development of technology determined? so far as a technology is socially constructed, its development is determined by socio-cultural as well as political factors. for example, politicians argue about how a certain technology is designed, developed and used. related to this, pinch once said, “what the social constructivist work points to is that the design and adaptation of technology should be part of the political agenda. in other words, these issues should be opened up for debate among wider constituencies than at present. there is no inevitable logic of development. there is choice. and this draws attention to the technology we never get.” (pinch, 1996). the hard version of technological determinism stresses that technology is a determinant factor for social existence. in this connection, marx once said, “in acquiring new productive forces men change their mode of production, and in changing their mode of production they change their way of livingthey change all their social relations. the hand-mill gives you society with the feudal lord, the steam-mill, society with the daniel tessema ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 68 industrial capitalist” (marx, 1847). a particular technology, according to hard technological determinism, is a necessary condition for determining social organization. the soft version, on the other hand, considers technology as a facilitating factor which leads to social changes. winner gives two hypotheses on td. in his words, “technological determinism stands on two hypotheses: (1) that the technical base of a society is the fundamental condition affecting all patterns of social existence and (2) that changes in technology are the single most important source of change in society” (winner, 1977). the notion of technological determinism is also discussed by some anthropologists. for instance, the anthropologist leslie white, once said, “we may view a cultural system as a series of three horizontal strata: the technological layer on the bottom, the philosophical on the top, the sociological stratum in between. these positions express their respective roles in the culture process. the technological system is basic and primary. social systems are functions of technologies; and philosophies express technological forces and reflect social systems. the technological factor is therefore the determinant of a cultural system as a whole. it determines the form of social systems, and technology and society together determine the content and orientation of philosophy” (white, 1949). does technology determine society? in my view, it is society which has the capacity to influence every single pattern of technology. human freedom will be diminished if technology becomes the primary determinant of society. social construction of technology approach argues that humans shape technologies and vice-versa. technology is shaped and reshaped by humans to satisfy their needs. the focal points of social constructivism are social groups and flexibility in technological development. social constructivists, such as bijker et al. (1987), argue that there exists flexibility in the design of technology. it is believed that the relationship between humans and the natural world is complex. for social constructivists, the cause and effect sequence of technology is necessarily not linear. they come up with an effective multi-directional model as the best alternative. the model they suggest is believed to integrate social groups and technological artifacts. social constructivism emphasizes on the relevance of social groups, the multi-directional nature of technological design as well as social conflicts on values. it gives an insight that we use as a basis for understanding the role of technology. it also explains what factors make technological developments achieve, how values are embedded in its development process and how society is linked to technology. social constructivists reject technological determinism. for them, no technology has a logical order of development. technological development is contingent on various factors. in my opinion, technologists are capable of looking at the natural world through human interests lens and make things that are suitable for socio-cultural contexts. social constructivism puts emphasis on values in technology. the material outcomes of technological development are shaped by values. thus, technology becomes value-laden. according to this approach, technology is constructed socially. humans in different walks of life engage themselves in demanding, making, using and regulating technology. when humans design technology, they are designing their way of life. the transformation of society is created in the technological design process. we need to understand what the implications of a technology are because it is not easier for us to know a lot about how a technology functions, its environmental and social impacts. we should examine technology. in my belief, examined technology is worth having. before we accept a new technology, we need to question how it influences our day-to-day life activities since technology is part of human interaction. technology is an element of culture. new technologies get integrated into societal practices through diffusion. societies adapt themselves to new technologies. but, when new technologies come into conflict with interests of different groups, ethical questions arise. the impact that a technology has on society and the need for ethical reflection depends on who is affected by it. the concept technological determinism is used to show the relationship between technology and human activity. moreover, technological determinism ranges from the explanation of autonomous technology to the view that technology is the most dominant factor in social change. according to bimber (1994), there exist different approaches, what he calls accounts, to the concept of technological determinism. firstly, normbased account tends to interpret technological daniel tessema ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 69 determinism as a cultural phenomenon. while unintended consequences account views technological determinism in terms of unpredicted social effects of technology, logical sequence account sees technological determinism as a natural universal law. how marx views td? for marx (1847), humans are the main factors in the development of forces of production. the role of technology for him is facilitating the process. different writers advance their arguments about marx and technology. for example, winner (1977) argues that it was marx (1847) who designed the coherent theory of autonomous technology. it seems that marx gave technology a central place in the area of human development. on the other side, marx is believed to be no technological determinist. for instance, rosenberg (1976) argues that marx viewed historical change in terms of a social process rather than a technological one. mackenzie (1984) strengthens this idea by arguing that marx forces of production should not be equated with technology. for marx, technology as a productive force has a role to play. however, the link between technology and productive forces remains the central problem or issue of discussion. although several interpretations are given by scholars concerning why and how technology is influential, the main point is the importance of it in bringing about social changes. bridging the gap between the two camps would seem difficult, but not impossible. the concept td is beyond this debate. marx should be acknowledged for laying the foundation. is technology autonomous? according to some philosophers such as ellul (1964), technology is seen as something outside of society. it is presented as independent, self-governing and self-determining force. furthermore, technology is not considered as a product of society. no human can control it. one of the renowned theorists who adopted this perspective is ellul (1964). he declared confidently that ‘technique has become autonomous; it has fashioned an omnivorous world which obeys its own laws and which has renounced all tradition’ (ellul, 1964). for him, no society is able to shape technology and every technological system is being shaped by technology itself. postman also argues that “technique tends to function independently of the system it serves” (postman, 1993). denying the inevitability of technological effects, postman (1993) insisted on the unpredictability of such effects. autonomy, being a western liberalism idea, gives persons the ability to govern themselves. but, it is seen that social conditions restrict individuals’ autonomy. ellul (1964) does not agree with such an idea. for him, there can be no human autonomy in the face of technical autonomy. my question here is does technology have its own will? it is true that technology has a purpose. but, its purpose is designed by humans. it is being shaped by society. technology is subject to human control since it could easily be turned off by humans without its consent. although some theorists such as pitt (1987) consider technology as a self-generating force, they fail to present it as a conscious being having a desire. technology is incapable of being explained and its autonomy is confined within some limits. according to habermas (1970), technology is not an independent force. it is society which exercises sovereign power over technology. for him, societies are capable of employing ethical conceptions to control the norms of practice in technological advancement. habermas’s (1970) conception of td puts emphasis on norms of practice. in my view, it is possible to consider technology autonomous when these norms are removed from ethical discussion. heilbroner’s (1961) view of td is incompatible with that of habermas’s (1970). for heilbroner (1961), technology is independent of cultural and social factors. he is describing a fixed sequence of technological developments. i also believe that it is not by chance that the steam-mill follows the hand-mill. the sequence is given by nature and it is capable of deriving social changes independently. for heilbroner (1961), the rise of capitalism and its demand led to technological innovation. as a result, technology has started to be seen as impersonal force. according to winner, it is possible to manipulate individual developments. but, technological evolution cannot easily be controlled. technological change is an accumulation of unanticipated results. thus, we adapt such a technological drift rather than controlling it. the system embeddedness of technology might have a constraint on our cultural system. this, in turn, might result in the loss of human agency. ellul (1964) views technology as something which has replaced nature. technique, for him, is the home in which human beings daniel tessema ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 70 live. his technique is something artificial, autonomous, that is, self-determining. moreover, technique is not goal-oriented, but it is known for its growth. the parts of a technique are inseparable. technique is capable of encompassing every social phenomenon. because technique comprises psycho-social patterns, it forces human beings to adapt themselves to it. technique dominates our values and ideas, according to him. technological determinism as a theory pays due attention to a cause and effect relationships. it attempts to differentiate a cause from an effect. moreover, as an explanation of change, it gives a single cause. being monistic, td involves a kind of reductionism aiming at reducing a complex whole to a part. reductionism is not far from criticism since it is hardly possible to isolate a single cause from any social process. technological determinists attempt to see everything in terms of technology. determinists consider human beings as homo faber-users of tools. in this connection, thomas (1841) said that, “without tools man is nothing; with them he is all.” it is true that technology has been contributing its part to the success of human activities. whenever we develop a certain technology, we are directly or indirectly shaping ourselves. writers on technological determinism argue that technological system is primary and any type of social system is a function or product of technology. it is the technological factor which solely determines the form of social system. td is a mechanistic mode of explanation. a machine serves a designated function. it operates according to cause and effect. a machine is autonomous which can run. it can run independently of human intervention. a machine, however, fails to select its own goal. application of sophisticated technology might have an implication which is not wholly protected. but, we need to take in to account that to what degree we the users become part of a technology when utilizing it. technological determinism is also associated with what is called reification, treating an abstraction as a material thing. while reifying, we treat technology as a single tool with a homogenous character. such philosophers as heidegger treated technology as a monolithic phenomenon and ellul (1964) referred technique as “the totality of methods rationally arrived at and having absolute efficiency in every field of human activity”. moreover, technique is “the ensemble of practices by which one uses available resources to achieve certain valued ends” (ellul, 1964). one shortcoming of ellul’s (1964) definition of technique is that a technology has different manifestations in different social contexts. the flexibility of technology might vary according to different services it provides. in this regard, technology remains non monolithic. is technology a means or an end? according to ellul (1964), technology is an end in itself rather than a means to some other ends. some critics, however, argue that technology serves as a means to meet societal demands. in this sense, if technology is a means then it would be hard to stop its developments. it is also difficult to avoid such technological developments. is technology neutral? some theorists propose that technology is neither good nor evil in itself. it rather remains neutral. they say that what matters most is not the technology but the way in which we prefer to use it. moreover, technology is not either moral or immoral. it is ethically neural. standing against the neutrality of technology, ellul (1964) claims that whether or not technology has good or evil outcomes mainly depends upon the way how it is utilized. according to him, “technique carries with it its own effects quite apart from how it is used. no matter how it is used, it has of itself a number of positive and negative consequences. this is not just a matter of intention’’. technology seems somehow neutral in the sense that its use might have a role in molding our activities. commentators on technological determinism argue that technology is non-neutral. they say that the technology we use determines our world view. for postman, technology is not neutral. he argues that,” the uses made of technology are determined by the structure of technology itself.” (postman, 1993). in addition to this, winner is tending to see the political non-neutrality of technology in the sense that technology is designed to open some social options and to close others. i also argue that technology is not-neutral. it is associated with its social usage. we cannot detach technology from social context since technology itself is a social product. technological determinism can also be manifested in terms of universalism. technology could be outside the framework of specific social, cultural or historical context. it does not, however, mean that a particular technology is universally associated with identical daniel tessema ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 71 social patterns. technological determinism is also associated techno-evolutionism which is a type of developmental determinism and the theorists endeavor to interpret change in terms of progress. progress is defined by such theorists in terms of successive developmental stages. there is a link between social progress and that of technological since development in technology is an important precondition for societal development. technological change produces certain social changes. thus, society and technology are related. is technology creating problems or solving them? it is true that human beings have been benefiting from technology. humans are living in a world of technology. thus, ethical issues should be included together with the advancement of technology before the moral fabric of the society is eroded and civilization is collapsed. human values must be taken in to consideration. some writers argue that although humans are eager to exploit technology, it remains autonomous. the main point is that for human beings to remain subjects of technology, they need to accept the common value of technology. it is believed that society and technology shape with one another. they are interconnected. the point i need to underline is that socio-cultural as well as political factors have an influence on the development of technologies that are existing now. in this connection, winner, in his work, “do artifacts have politics?” tries to address the relationship which exists among systems of power, authority and that of technology. his argument is that no particular artifact exists without a distinctive type of social arrangement. thus, whenever we adopt a particular technology, it means that we are also adopting a particular social order. according to winner, artifacts are capable of enforcing social agenda. it is subtle that technology is a collection of artifacts and socio-cultural practices and no technology has a meaning by itself. a technology becomes meaningful when it is attached to social practices. it can never exist and be used independently of social relationships. similarly, social practices may fail to exist without technology. can man-made material objects come in to being in a vacuum? do they have meaning in a vacuum? or can they be used in a vacuum? technology as a material object is created in a social context. it functions in complex social arrangements. when we recognize the inseparability of technology from society, it would become vivid that no technology remains as an independent entity. focusing only on autonomous technology is not only an attempt to separate it out from the context it was made, but also from the socio-cultural meaning attached to it. a technology accomplishes designated tasks when members of a group work together. let me take an example. these days, computers in an automobile industry are helping mechanics during automobile repair. the introduction of computer system helps mechanics’ task of diagnosing cars. but, computers do not know how to interact with clients. they function with the help of humans. do computers feel responsibility and accountability when we assign certain tasks to them? as far as humans design technologies, they are responsible. though technology is a dynamic force having an impact on society, we need to interpret technology in the context of society. 3. conclusion technological determinism and social determinism have answered some questions concerning the independence, design and use of technology. however, several issues remained unanswered because of the complexity of the two perspectives. technology has penetrated all spheres of human existence. ethics of technology is not only vital for developing an ethical framework for the assessment of emerging technologies such as genetic engineering, but also for the ethical issues related to creative and innovative technologies. for technological determinists, technology not only drives, but also defines social change. social determinists argue against this idea. for them, social and cultural practices shape technological development. when will the debate between the two camps end? 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(1977). autonomous technology: technics-out-of-control. cambridge, ma: mit press. http://visual-memory.co.uk/daniel/documents/ 73 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu review paper recent trend in synthesis of indenoisoquinoline analoges as topoisomerase i inhibitor and cytotoxic property: review digafie zeleke, yadessa melaku department of applied chemistry, school of applied natural science, adama science and technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 20 november 2020 received in revised form 18 december 2020 accepted 02 january 2021 indenoisoquinolinediones are a class of non-camptothecin topoisomerase i inhibitors that display marked cytotoxic and potent antitumor properties. currently phase 2 clinical trial of three indenoisoquinoline derivatives lmp400 (indotecan, nsc724998), lmp776 (indimitecan, nsc725776) and lmp744 (mj-iii-65, nsc706744) is on progress. in the last two decades, various synthetic methodologies have been developed for syntethesis of indenoisoquinolines and its analogs. these compounds are of great research significance owing to their novel structures and broad biological activities including antitumor, cytotoxic and topomerase i inhibitory properties. this review address the recent trend in synthesis experimental protocols of indenoisoquinolines and their cytotoxicity, antitumor and topomerase i inhibitory efficacy during the period 2015-2020. the synthetic methodologies and bioactivities reviewed herein might serve as a reference for researchers who are interested to work in the area. keywords: indenoisoquinolinediones cytotoxic antitumor 1. introduction cancer is a major health problem projected to affect about 22 million people by 2030 and has become the second leading cause of morbidity and mortality after cardiac disease.(bray et al., 2012) it is believed that one of the causes of caner is a genetic disease caused due to mutations in genes associated with cell proliferation and cell death that results in dna damage.(baikar and malpathak, 2010) among the variety of molecular targets for cancer therapy, dna topoisomerases (topos) are well-characterized targets owing to their essential roles in triggering, controlling, and modifying a wealth of topological dna problems during cell proliferation, differentiation and survival.(chen et al., 2013; hu et al. 2018) the human genome encodes six topoisomerases whereas e. coli encodes four.(pommier et al., 2010)on  corresponding author, e-mail: yadessamelaku2010@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.314 the basis of their mechanisms, eukaryotic topoisomerases can be classified into two major classes, type i and type ii, but there are subtypes under each class.(delgado et al., 2018; hevener et al., 2018; liu et al., 1980). 1.1. dna topoisomerase i inhibitors camptothecin (cpt) is a potent antitumor drug, an alkaloid isolated from the chinese tree, camptotheca acuminate, also known as the “tree of joy” by monroe wall and coworkers (figure 1) (baikar and malpathak, 2010). camptothecin carboxylate was tested clinically in the mid-1970s and showed anticancer activity, but was discontinued because of its side effects(pommier, 2006; wall et al., 1993; yu et al., 2012).two watersoluble camptothecin derivatives (irinotecan and topotecan) are presently approved by the food and drug http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021.............. digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 74 administration (fda) for intravenously administration (figure 1). topotecan is used to treat ovarian cancers and small-cell lung cancers (sclc), but yet with some side effects (pommier, 2009). irinotecan is approved by the fda for colorectal tumors. it is a prodrug and needs to be converted to its active metabolite sn-38 by carboxylesterase (figure 1) and it has also some undesired effects (pommier, 2009). two other newer camptothecin derivatives, gimatecan and belotecan are in clinical trials (figure 1) (beecham and corp, 1995; pommier, 2009; zhang et al., 2005). 1.2. indenoisoquinolines as topoisomerase i inhibitors though camptothecin derivatives are effective against previously resistant tumors and are the only class of topoisomerase i (top1) inhibitors approved for cancer treatment in 1970s, yet, they have pharmacologic and clinical limitations that restrict the dose of active drug that can reach the tumor while sparing normal tissues (pommier, 2012; staker et al., 2005). a major limitation to the clinical efficacy of camptothecin-containing therapies is represented by drug resistance (beretta et al., 2006). the “classical” mechanisms of resistance to cpts have been extensively studied and include: i) pretarget events, which result in reduced accumulation or inadequate subcellular localization of drug in the cell (i.e. drug efflux, metabolism and intracellular drug distribution); ii) target related events, which result in reduced drug-target interaction (e.g., topoi downregulation or gene mutation); iii) post-target events, which result inalterations in the cellular response to dna damage generated by the formation of the ternary complex (e.g., tyrosyl dna phosphodiesterase 1, tdp1) were typical (beretta et al., 2013; sharma et al., 2015). in 1978, pommier and cushman synthersized the first indenoisoquinolines (later named as nsc 314622) unexpectedly while treating a cis substituted isoquinolone with socl2 afforded the aforementioned indenoisoquinolineinstead of its acid chloride (figure 2). the topoisomerase i inhibitory activity of indenoisoquinolines was identified in 1998 when a compare algorithm analysis was performed on nsc 314622, which indicated that it may act in a manner similar figure 1: camptothecin and its clinically approved derivatives digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 75 figure 2: the first synthesized indenoisoquinoline to that of camptothecin and derivatives. after being confirmed in vitro test, more potent indenoisoquinoline derivative was developed with an the maximal concentration of drug to cause 50% inhibition of biological activity of cancer cells (ic50) of 20 μmol/l (burke and mi 1994; cushman and cheng 1978; marzi et al. 2018; morrell et al. 2006; strumberg et al. 1999). 1.3. biological activities of indenoispquinolines irinotecan and topotecan are the only current approved top1 inhibitors approved by fda for the treatment of cancer. however, these campotothecin derivatives are not ideal drug molecules owing to reversablity of the top-dna cleavage complex and structurally they suffered from lactone ring opening to form a hydroxy acid that has a high affinity for human serum albumin. as a result of this pharmacokenetic problem, there is a great intrest in the development of non-campotothecin top1 inhibitors among which indenoisoquinolinediones are one of them. structurally, indenoisoquinolinediones are highly fused compounds which contain a planar tetracyclic heteroring system equipped with multifarious functionalities as exemplified by the lead compound (ncs 314622) (figure 2) (morrell et al., 2006). they have been demonstrated to inhibit topoisomerase i enzymes by intercalating between the dna base pairs and to stabilize a ternary complex consisting of the drug molecule, dna and topoisomerase i (morrell et al., 2006). the indenoisoquinolines, like the camptothecins, stabilize dna–top1 cleavage complexes by intercalating at the dna cleavage site, resulting in inhibition of the re-ligation reaction (marzi et al., 2018). motivated by this discovery, around 400 indenoisoquinoline derivatives have been synthesized and evaluated for top1 inhibition using recombinant enzyme and purified dna substrates and cellular assays in the nci-60 cell line panel by various scientists across the globe (pommier and cushman, 2009). most of the synthesized indenoisoquinolines were assessed for antiproliferative activity against 55 different human cancer cell lines of diverse tumor origins at the usa national cancer institute screen. the results of topoisomerase i dna cleavage experiments were reported semiquantitatively and provide a means of comparison with the biological activity of camptothecin (++++) and with the the lead compound (nsc 314622) (++) as follows: +: weak activity; ++: similar activity as the parent lead compound (nsc 314622); +++ and ++++: greater activity than the lead compound (nsc 314622); ++++: similar activity as 1 μm camptothecin (morrell et al., 2006; strumberg et al., 1999). 2. synthesis and biological evaluation of indenoisoquinolines because of the multiple disease nature of cancer, one chemotherapeutic agent does not work on all cancer types. thus, specific biomolecule targeted therapies have become more popular which requires various effective anticancer agents (foto et al., 2020). since the discovery of indenoisoquinolines as a novel class of potential anticancer drug candidates, extensive structural modifications have been introduced by altering the substituent of the tetracyclic pharmacophore. out of nearly 400 synthesized indenoisoquinoline derivatives, currently three of them namely, indotecan (lmp400), indimitecan (lmp744) and lmp776 (mj-iii-65, nsc706744)) were promoted to a phase i clinical trial in 2010 (figure 3) and their phase 2 clinical trial is on progress (marzi et al., 2019, 2020). indenoisoquinolines offer a number of potential advantages over the camptothecins, including greater chemical stability, formation of more persistent cleavage complexes, and induction of a unique pattern of dna cleavage sites (nagarajan et al., 2003). a varieties of reactions and synthetic methodologies that digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 76 figure 3: indenoisoquinoline derivatives in the firstphase clinical trial have been developed to construct indenoisoquinolines including condensation (conda-sheridan et al., 2013) of indenoisochromenone with a primary amine, suzukimiyaura cross-coupling (lebrun et al., 2011) reaction followed by ring-closing metathesis, (liu et al., 2015) oxidative cyclization of cis acid produced by the condensation of a homophthalic anhydride and a schiff base. several other reactions such nucleophilic substitution, sandmeyer reaction, reduction and oxidation techniques have been employed to introduce and optimize varied functional groups on the scaffold (kiselev et al., 2010; lebrun et al., 2011; nagarajan et al., 2003, 2004). among the latest synthetic efforts, nguyen et al. (2015) synthesized eighteen nitrated 7-, 8-, 9-, and 10hydroxyindenoisoquinolines bearing a 3-nitro substituent (figure 4), all of which were potent dual top1−tdp1 inhibitors, (conda-sheridan et al., 2013; eun-jung et al., 2012; morrell et al., 2007) using oxidative cyclization of cis acid produced by the condensation of a homophthalic anhydride and a schiff base (scheme 1) (nguyen et al., 2015). 2.1. synthesis of 8-hydroxy-9-methoxy-3nitroindenoisoquinolines and 9-hydroxy-8methoxy-3-nitroindenoisoquinolines the synthesis of nitrated 9-hydroxy-8methoxyindenoisoquinolines 10, 12, and 14, (scheme1 and 2) and the synthesis of 8-hydroxy-9methoxyindenoisoquinolines 21, 23, and 25 (scheme 3 and 4) were outlined. these synthesis began with commercially available homophthalic acid 1 which was nitrated with fuming hno3 to provide the diacid 2, which underwent dehydration in accl to provide anhydride 3 (scheme 1). the reactive hydroxyl groups in vanillin (4) and isovanillin (15) were protected with a benzylgroup. benzylvanillin (5) and benzylisovanillin (16) reacted with 3-bromopropylamine hydrobromide to give schiff bases 6 and 17, which uponcondensation with anhydride 3 in chcl3 furnished cis acids 7 and 18 n o2n o o oh ome r n o2n o o ome oh r n o2n o o r3 9 8 3 8 9 oh 3 7 8 910 10 r = morpholine 12 r = imidazole 14 r = nh2 22 r = morpholine 23 r = imidazole 25 r = nh2 31 r = morpholine 32 r = imidazole 33 r = nh2 7-hydroxy 57 r = morpholine 58 r = imidazole 59 r = nh2 9-hydroxy 43 r = morpholine 47 r = imidazole 51 r = nh2 8-hydroxy 44 r = morpholine 48 r = imidazole 52 r = nh2 10-hydroxy figure 4: proposed top1−tdp1 inhibitors digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 77 in good yields with excellent diastereoselectivities. treatment of 7 or 18 with socl2 (neat) provided a mixture of indenoisoquinoline 8 or 19 and their regioisomers, which was confirmed by 1h nmr spectroscopy. isomers 8 and 19 appeared as the major products after column chromatography separation. the yields were low due tothe nitro group activating epimerization to the transdiastereomers, which exist in pseudodiaxial conformations and do not oxidize and cyclize in socl2 (nguyen et al., 2015). the displacement of the terminal bromide in 8 or 19 with morpholine or imidazole in 1,4-dioxane, or azide in dmso, yielded the benzyl-protected compounds 9, 11, and 13 (from 8) (scheme 2), or 20, 22, and 24 (from 19), (scheme 4) (morrell et al., 2007). the treatment of the benzylprotected starting intermediates with aqueous hbr at 70 °c for 4−5 h, followed by dilution with acetone and then concentration (iterated three times), afforded a mixture that was suitable for vacuum filtration to provide the desired phenols 10, 12, 14, 21, 23, and 25 in high yields (80−100%) and excellent purity (nguyen et al., 2015). reagents and conditions: (a) fuming hno3, 0−23°c; (b) accl; reflux; (c) bncl, dmf, k2co3, 23°c; (d) 3-bromopropylamine hydrobromide, et3n, na2so4, chcl3, 23°c; (e) chcl3, 0−23°c; (f) socl2, 0−23°c; scheme 1. synthesis of intermediate 8 reagents and conditions: (a) morpholine, 1,4-dioxane, 23°c; (b) aqueous hbr, 70°c; (c) imidazole, 1,4-dioxane, 70°c; (d) nan3, dmso, 23°c; (e)(i)p(oet)3, benzene, reflux, (ii) aqueous hbr, 70°c. scheme 2. synthesis of nitrated 9-hydroxy-8-methoxyindenoisoquinolines digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 78 reagents and conditions: (a) bncl, dmf, k2co3, 23°c; (b) 3-bromopropylamine hydrobromide, et3n, na2so4, chcl3, 23°c; (c) anhydride 23c, chcl3, 0−23°c; (d) socl2, 0 to 23°c scheme 3. synthesis of intermediate 19 reagents and conditions: (a) morpholine, 1,4-dioxane, 23°c; (b) aqueous hbr, 70°c; (c) imidazole,1,4-dioxane, 70°c; (d) nan3, dmso, 23°c; (e) (i) p(oet)3, benzene, reflux, (ii) aqueous hbr, 70°c. scheme 4. synthesis of nitrated 8-hydroxy-9-methoxyindenoisoquinolines 2.1.1. synthesis of 7-hydroxy-3-nitroindenoisoquinolines commercially available salicylaldehyde 26 was obenzyl protected to give 27, which reacted with 3bromopropylamine to afford schiff base 28 (scheme 5). condensation of 28 with anhydride 3 in chcl3 yielded cis acid 29, which upon treatment with socl2, followed by alcl3 in 1,2-dichloroethane, provided indenoisoquinoline bromide 30 in good yield (kang et al., 2014; mancuso at al., 1978). the displacement of the bromide in 23 with morpholine, imidazole, or nan3, followed by a staudinger reduction of the azide intermediate and acidic hydrolysis with methanolic hcl, provided the desired amines 31, 32, and 23, respectively. the pure products were isolated without chromatographic purification (nguyen et al. 2015). 2.1.2. synthesis of 8and 10-hydroxy-3-nitroindenoisoquinolines a similar approach was implemented to prepare 8hydroxy-3-nitroindenoisoquinolines as shown in scheme 6 (conda-sheridan et al., 2013) the condensation of 36 with anhydride 3 provided a mixture of the desired cis acid 37 and its trans diastereomer. boiling the mixture in chcl3, followed by filtration, helped to remove the unwanted trans acid and provide the pure cis acid 37 as a sole product. unfortunately, the treatment of 37 with socl2 0 to 23°c, digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 79 reagents and conditions: (a) bnbr, dmf, k2co3, 23°c; (b) 3-bromopropylaminehydrobromide, et3n, na2so4, chcl3, 23°c; (c) anhydride 3, chcl3, 0 to 23°c; (d) (i) socl2, 0−23°c, (ii) alcl3, 1,2-dichloroethane, reflux; (e) socl2, reflux. scheme 6. synthesis of 8and 10-hydroxy-3-nitroindenoisoquinoline intermediates. followed by alcl3 in refluxing 1,2-dichloroethane, did not yield the desired bromide 39. however, transformation was observed when cis acid 37 was heated with socl2 (neat) at reflux for 4 h, during which the solution turned to clear orange (nguyen et al., 2015). the treatment of the mixture of bromides 39 and 40 with morpholine and imidazole, followed by chromatographic purification, allowed the isolation of each pure morpholinyl and imidazolyl 8-and 10-benzyloxy compounds 41, 42, 45, and 46 (scheme 7). after chromatographic separation, all of the benzylprotected materials were subjected to a 3 h debenzylation with aqueous hbr (48 wt %) to provide the desired 8and 10-hydroxyindenoisoquinolines 44, 44, 47and 48 in good yields and purities (nguyen et al., 2015). 2.1.3. synthesis of 9-hydroxy-3-nitroindenoisoquinolines the treatment of 53 with 3-bromopropylamine hydrobromide and et3n provided schiff base 54, which upon condensation with anhydride 3 produced cis acid 55 in good yield and excellent purity (scheme 8) (nguyen et al., 2015). the treatment of 55 with morpholine reagents and conditions: (a) morpholine, 1,4-dioxane, 70°c; (b) hbr, h2o, 70°c; (c) imidazole, 1,4-dioxane, 70°c; (d) nan3, dmso, 23°c; (e) (i) p(oet)3, benzene, reflux, (ii) hbr, h2o, 70°c. scheme 7. synthesis of 8and 10-hydroxy-3-nitroindenoisoquinoline digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 80 or imidazole in thf provided the corresponding displacement products, which were then stirred in freshly made methanolic hbr or hcl to afford the hbr and hcl salts 57 and 58, respectively. the synthesis of amine 59 by the previous methodology involving reduction of the azide intermediate with p(oet)3 in benzene (scheme 4) was not successful due to complications in purification and isolation of the compound in solid form. the staudinger reaction was therefore reattempted by treating the azide intermediate, obtained from 56, with pph3 in thf (instead of p(oet)3 in benzene), followed by 4 h acidic hydrolysis with methanolic hbr. this modification provided the desired amine 59 in 32% yield with excellent purity. 2.1.4. top i inhibitory and antiproferative properties of indenoisoquinolines all of the synthesized compounds (collectively shown in figure 4) were evaluated for top1inhibitory, tdp1 inhibitory potencies and antiproliferative activities (nguyen et al., 2015). the results revealed that the 3-nitro group seems to facilitate intercalation into free dna so that 43, 44, 47, and 48 with large substituents on the side chain, all act as top1 suppressors at 0.1, 1.0, 10, and 100 μm, respectively (nguyen et al., 2015). the nitrated compounds also displayed a significant improvement in terms of cytotoxicity when compared to their corresponding dimethoxy analogues, with the 9-hydroxy8-methoxy series 10, 12 and 14 possessing low nanomolar antiproliferative potencies (mgm values of 16−21 nm). indeed, the order of top1 inhibition and cytotoxicity went from the 9-hydroxyl series 56−59 as the most active and cytotoxic (top1 inhibition ++++ or more, mgm 14−117 nm) to the 8-hydroxyl series 43, 47, and 51 (+++ to ++++, 56−407 nm), and in the 7-hydroxyl series 31−33 and the 10-hydroxyl series 44, 48, and 52 (++ to +++ for both series, 234 to 3550 nm for the 10hydroxyl) as the least active and least cytotoxic (morrell et al., 2007). 2.2. discovery of potent indenoisoquinoline topoisomerase i poisons lacking the 3nitrotoxicophore the nci-60 screening service recently proposed a policy wherein submission of molecules containing “problematic” functionalities, (morrell et al., 2006) including reagents and conditions: (a) 3-bromopropylamine hydrobromide, et3n, na2so4, chcl3, 23°c; (b) anhydride 3, chcl3, 0−23°c; (c) (i) socl2, 23°c, (ii) alcl3, 1,2-dichloroethane, 0−23°c; (d) (i) morpholine, thf, 70°c, (ii) hbr, meoh, 23°c; (e) (i) imidazole, thf, 70°c, ( hcl, meoh, 23°c; (f) (i) nan3, dmso, 23°c, (ii) pph3, thf, 70°c, (iii) hbr, meoh, 70°c scheme 8. synthesis of 9-hydroxy-3nitroindenoisoquinolines e f digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 81 nitro groups, are discouraged. accordingly, beck et al. (2015) adopted a research to discover a suitable bioisosteric replacement for the 3-nitro group on the indenoisoquinoline system that would maintain or improve top1 poisoning activity and growth inhibitory potency (beck et al., 2015). the synthesis was commenced with benzaldehyde 60, which was reduced with nabh4 to provide the bromobenzylic alcohol 61 (scheme 9). rosenmund−von braun reaction with cucn and in situ hydrolysis and lactonization of the intermediate yielded compound 62. phthalide 62 was subjected to radical bromination, and the obtained 3bromophthalide intermediate 63 was hydrolyzed to produce 3-hydroxyphthalide 65 which was condensed with phthalide (64) in refluxing methanol−etoac with naome and then dehydratively cyclized in refluxing ac2o to afford 66 (beck et al., 2015). indenobenzopyrans 72a-d were synthesized by nearly identical synthetic routes, where the only point of difference was in step c (scheme 10) (conda-sheridan et al., 2013; robert et al., 1988). phthalic acid 73 was converted to its anhydride 74 in refluxing accl. anhydride 74 was reduced with nabh4 in thf to give a 1:1 mixture of 5and 6-(trifluoromethyl) phthalides 75a and 75b which were readily separated by silica gel column chromatography (marzi et al., 2002). phthalides 75a and 75b were separately subjected to radical bromination and subsequent hydrolysis to provide 3-hydroxyphthalides 76a and 76b. indenobenzopyrans 78a and 78b were obtained by the condensation of 3-hydroxyphthalide 77a and 77b with phthalide (4), and dehydrative cyclization of the unisolated intermediate was carried out as before in refluxing ac2o (scheme 11) (beck et al., 2015). reagents and conditions: (a) nabh4, meoh, 0°c to room temp; (b) (i) cucn, dmf, reflux, (ii) h2o, reflux; (c) nbs, aibn, ccl4, reflux; (d) koh, h2o, reflux; (e) (i) naome, meoh, etoac, reflux, (ii) ac2o, reflux. scheme 9. synthesis of 3-fluoroindenobenzopyran (66) reagents and conditions: (a) kno3, h2so4, 0°c to room temp; (b) h2, pd/c, etoac; (c) (i) nano2, 37% hcl, 0°c, (ii) cucl, 37% hcl, 0°c to reflux (69a), or (i) nano2, 48% hbr, 0°c, (ii) cubr, 48% hbr, 0−80°c (69b), or (i) nano2, 37% hcl, 0°c, (ii) ki, 0°c to room temp (69c), or (i) nano2, 37% hcl, 0°c, (ii) nacn, cucn, 0°c to room temp (69d); (d) nbs, aibn, ccl4, reflux; (e) koh, h2o, reflux; (f) (i) naome, meoh, etoac, reflux, (ii) ac2o, reflux. scheme 10. synthesis 3-substituted indenobenzopyran 72a-d digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 82 3-hydroxyphthalide 65 was used to generate 81b through nucleophilic substitution and condensation reaction (scheme 12). (s)-3-amino-1, 2-propanediol (82) was condensed with indenobenzopyrans 66, 72a-d, 78a-b, 80 and 81, to produce indenoisoquinolines 83-86 (scheme 13). 1-(3aminopropyl) imidazole (87) was condensed with the same indenobenzopyrans, to yield indenoisoquinolines 88-91. in the same way, 3-morpholinopropylamine (92) was condensed with indenobenzopyrans 66, 72a and 72c to produce indenoisoquinolines 93a-c (scheme 14). anhydride 94 was reduced with nabh4 in phmedmf and the reduction product was cyclized to provide phthalide 95 which was converted 98 in three steps (scheme 15). in similar way to its carbocyclic analogues, lactone 98 was condensed with primary amines 87, 92 and 10 to yield indenoisoquinolines 99, 100, and 102 (scheme 16). reagents and conditions: (a) accl, reflux; (b) (i) nabh4, thf, 0°c, (ii) hcl; (c) nbs, aibn, ccl4, reflux; (d) koh, h2o, reflux; (e) (i) naome, meoh, etoac, reflux, (ii) ac2o, reflux. scheme 11. synthesis of indenobenzopyran 78a, b reagents and conditions: (a) nasme, dmf, 120°c; (b) (i) naome, meoh, etoac, reflux, (ii) ac2o, reflux; (c) m-cpba, chcl3, room temp scheme 12. synthesis of indenobenzopyran 80 and 81. reagents and conditions: (a) meoh−chcl3, reflux; (b) chcl3, reflux. scheme 13. synthesis of indenoisoquinolines 83-91 a b digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 83 scheme 14. synthesis of indenoisoquinolines 93a-c reagents and conditions: (a) (i) nabh4, phme, dmf, −20 to 35°c, (ii) 5 m hcl, reflux; (b) nbs, aibn, ccl4, reflux; (c) h2o, reflux; (d) (i) naome, meoh, etoac, reflux, (ii) ac2o, reflux. scheme 15. synthesis of indenobenzopyran 98 scheme 16. synthesis of indenoisoquinolines 99, 100and 102 2.2.1. top i inhibitory and antiproferative activities of indenoisoquinolines 88-102 among the bioisosteric compounds, 88, 89a, and 90a-c display the best top1 poisoning activities. the top1-mediated dna cleavage induced by these four compounds is between 75 and 95% that of 1 μm cpt (i.e. +++). mgm concentration of drug to cause 50% reduction in proliferation of cancer cells i.e. growth (gi50) values were calculated to be 0.692 μm for 88, 0.229 μm for 89, and 2.75 μm for 93a. compounds 88, 89a and 93a are substituted with the halogens f and cl. the other potential bioisosteres (i.e. i, cn, cf3, sme and so2me) did not display top1-mediated dna cleavage assay scores above ++. so the researchers had discosed that only fluorine and chlorine were identified as bioisosteres of nitro group on the basis of top1 poisoning activities and growth inhibitory potencies (antony et al., 2007; beck et al., 2015; pommier et al., 2014; sirivolu et al., 2012). 2.3. synthesis and cytotoxic evaluation of novel indenoisoquinoline-propan-2-ol hybrids functionalized propanes are often part of biologically active agents. particularly, the class of the β-amino propanols consists of multiple representatives with antimalarial, anticancer, src kinase inhibiting, antimicrobial, and antifungal properties (chennakesava et al., 2014; pham et al., 2016; robert et al., 1988). inspired by above literature reports, thi et al. (2016) developed a variety of novel indenoisoquinolines by combining the indenoisoquinoline scaffold with 2hydroxypropane unit (pham et al., 2016). in the process, the key starting material, benz[d]indeno[1,2-b]pyran5,11-dione 105, was synthesized using a two-step methodology. condensation of 2-carboxybenzaldehyde 93 with phthalide 64 in the presence of sodium methoxide in methanol/ethyl acetate (2:1) under reflux furnished intermediate 104, which could, after dehydrative acid-catalyzed lactonization in toluene, efficiently be digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 84 scheme 17. synthesis of indenoisoquinolines 106a–i. converted to indenobenzopyran 105 in 58% yield after recrystallization from ethyl acetate. derivatives 106a-i generated in high yields (81–96%) upon treatment of 105 with the appropriate primary amines, as shown in scheme 17 (morrell et al., 2006; pham et al., 2016). multiple indenoisoquinoline derivatives sar studies have demonstrated that the presence of hydrogen bonding groups (e.g., hydroxyl) on the lactam side chains correlates well with an increase in biological activity. to prove this principle emperically,the researchers derivatized n-allyl-substituted indenoisoquinoline 109g via hydroxybromination (pham et al., 2016). then 108 was converted into 109a-k in moderate to good yields (45–78%) after base-catalyzed nucleophilic substitution of the primary bromide by a series of primary or secondary amines or primary thiols in acetone or dmf at 65℃ (scheme 18). furthermore, intermediate 108 was converted to 110 via k2co3catalyzed nucleophilic substitution by water. compound 110 was then further acylated using acetic and isobutyric anhydride in the presence of 3 equiv of triethylamine to provide esters 111a, b in 62–65% yield. on the other hand, treatment of 2,3-propanediol 110 with tosyl or mesyl chloride resulted in the formation of the monosulfonylated diols 113 (54–58%) (pham thi et al. 2016). a final option involved the reaction of 108 with 3 equiv of sodium azide in order to furnish the corresponding azide 112 in good yield (81%) (pham et al., 2016). 2.3.1. top i inhibitory and antiproferative activities of indenoisoquinolines 106a-i, and 109-113 the synthesized indenoisoquinolines were evaluated in terms of their cytotoxicity profile against two human cancer cell lines, kb and hep-g2 (alley et al., 1988; kiselev et al., 2011; monks et al., 1991; vann et al., 2016). ellipticine was used as a reference compound. the results of this biological assessment, revealed the majority of the compounds exhibit at least moderate cytotoxicity against both cancer cell lines. 105i and 109a,c,e,k exhibited equal cytotoxic activity with the reference, 109a and 109e were the most promising (ic50 values of 0.82 and 0.47 μm and 0.82 and 0.69 μm, respectively, against kb and hep-g2) (pham et al., 2016). in the same year, thi et al. (2016) adopting another project wherein twenty three new indenoisoquinoline substituted triazole hybrids were prepared.(pham et al., 2016). in recent years, it has been commonly accepted that agents containing more than one pharmacophore can have superior efficacy as compared to single-pharmacophore drugs (solomon et al., 2010). they hypothesized that the introduction of triazole group into n-functionalized three-carbon side chain of indenoisoquinoline, especially indenoisoquinoline-propan-2-ols, could give potent biological compounds (monks et al., 1991). to confirm their hypothesis, they synthesized and evaluated novel triazole-indenoisoquinolines hybrids (monks et al., 1991). in their synthesis strategy, novel triazoleindenoisoquinoline hybrids were developedbased on a cui-catalyzed 1,3-cycloaddition between propargylsubstituted derivatives and the azidecontaining indenoisoquinoline 112 which was prepared by previous four-step methodology (haldón et al., 2015; pham et al., 2016). azidoindenoisoquinoline112 was transformed to triazole–indenoisoquinolinehybrids 113a–n in high digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 85 yields (60–80%) upon treatment with the appropriate 1propargyl derivative (scheme 19) (pham et al., 2016). scheme 18. synthesis of indenoisoquinoline 109-113 and ellipticine. digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 86 reagents and conditions: (a) 1.1 equiv ethynyl derivatives, 0.2 equiv dipea, 0.1 equiv cui, thf, reflux, 24 h; (b) 3 equiv ac2o, 2 equiv et3n, dmf, rt, 24 h. scheme 19. synthesis of triazole–indenoisoquinoline hybrids 113a–n and 114a, b. 2.3.2. top i inhibitory and antiproferative activities of indenoisoquinolines 113a-n and 114a, b the in vitro biological assessment of compounds (scheme 18 and 19) against two human cancer cell lines (kb-ccl-17, hepg2-hb-8065) (pham et al., 2016) revealed that most of the derivatives possess at least moderate cytotoxic activity. it is important to note that these separate pharmacophores display considerably less potent cytotoxic activities as compared to the most promising conjugates 113a-n. 2.4. synthesis and biological evaluation of new fluorinated and chlorinated indenoisoquinoline topoisomerase i poisons in 2016, beck d. et al. contined their effort to develop highly active analogs of the indenoisoquinolines in phase 1 clinical trial drugs indotecan (lmp400) (beck et al., 2014; maris et al., 2012) and indimitecan (lmp776) (maris at al., 2012; pommier and cushman, 2009), as well as the clinical trial candidate mj-iii-65 (lmp744) (beck et al., 2016). in the process, structural modifications of fluorinated and chlorinated indenoisoquinolines (pommier et al., 2014) were incoporatedto enhance their top1 poisoning activities. they synthesized a series of pentacyclic lactone intermediates that could be used to probe the effects of having different a-ring substitution patterns and different side chains on the lactam nitrogen. in these synthesis, 3-hydroxyphthalides 65 (pommier et al., 2014) and 69a (pommier et al., 2014) were each condensed with phthalide 64 under basic conditions (scheme 20) (shapiro et al., 1961). the 1,3-indanedione intermediates 116a and 116b were each cyclized in situ in refluxing ac2o to yield lactones 117a and 117b (shapiro et al., 1961) which were condensed with various primary amines (antony et al., 2007; beck et al., 2016; strumberg et al., 1999) provided indenoisoquinolines 118a-i (beck et al., 2016). besides monofloro indenoisoquinoline derivatves, this team synthesized 2,3-diflouro and 2,3-diocloroindenoisoquinoline derives (119a-b and 120a-b) by application related procedure discussed here (figure 5 ). 2.4.1. top i inhibitory and antiproferative activities of indenoisoquinolines 118a-120b the result of top1 inhibitory assement revealed that out of new compounds, 118d achieved a ++++ score, whereas 118h, and 118i achieved a +++ score (beck et al., 2016). among 3-fluoroor 3-chloro-substituted analogs, two top1 inhibitors (118h and 118i) were also found to be active in both recombinant tdp1 and tdp2 inhibition assays (beck et al., 2016). the most cytotoxic compound of the present series was the 3-fluoro derivative 118d having an imidazole-containing side chain, which displayed a gi50 mgm of 11 nm (beck et al., 2016). digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 87 reagents and conditions: (a) (i) naome, meoh, etoac, reflux; (ii) ac2o, reflux; (b) chcl3, meoh, reflux. scheme 20. synthesis of indenoisoquinolines 118a-i figure 5: diflouro and dicloroindenoisoquinolines by beck et al. (2016). 2.5. design and synthesis of chlorinated and fluorinated 7-azaindenoisoquinolines as potent cytotoxic anticancer agents that inhibit topoisomerase i motivated better bioactivity of 3-flouro and 3-chloro substituted analogs, elsayed et al. (2017), synthesized eighteen chlorinated and fluorinated 7‑azaindenoisoquinolines by avoiding indenoisoquinolines with nitro groups on aromatic systems to mitigate the toxic effect of nitro groups (elsayed et al., 2017). in their work, two strategies were involved to incorporate ring nitrogen and for the replacement of the 3-nitro group with halogens (elsayed et al., 2017). the anhydrides 121a and 121b (scheme 21) were prepared by published literature procedures (gwong-jen, 2010; kang et al., 2014). bromination of 5-methoxy-3-methylpicolinonitrile in the presence of the radical initiator aibn produced intermediate bromide 122 (kiselev et al., 2011) which was used directly in the next step without additional purification. the condensation of 122 with 121a and 121b in acetonitrile promoted by et3n afforded compounds 123a and 123b. oxidation of 123a and 123b with selenium dioxide provided azaindenoisoquinoline intermediates 124a and 124b. treating compounds 124a and 124b with nah in dmf at 0 °c, followed by reaction with 1-chloro-3-bromopropane, yielded the common intermediates 125a and 125b. the common intermediates 125a and 125b were used for the synthesis of the final compounds 126a−j and 127a−i by alkylation of the corresponding amines in dmf as shown in scheme22 (elsayed et al., 2017). 2.6. synthesis and cytotoxic evaluation of carboxylic acid-functionalized indenoisoquinolines functionalized carboxylic acids are often part of biologically active agents. they might provide a point of attachment for the synthesis of prodrugs so that the pharmacokinetics could be modulated and optimized. the importance of the carboxylic acid functional group digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 88 in drug design is illustrated by the fact that > 450 marketed drugs are containing carboxylic acid functional group (ballatore et al., 2013; dung et al., 2019). inspired by this fact, dung et al. (2019) synthesized a library of indenoisoquinoline acids in order to find out the influence of carboxylic acid functionalities in the n-lactam side chains of indenoisoquinolines on cytotoxic activities (dung et al., 2019). dung et al. (2019) first synthesized indenoisoquinoline acetic acid (scheme 23). piperonal 128 reacted with glycine methyl ester hydrochloride to give schiff base 130, which upon condensation with homophthalic acid anhydride furnished cis-acid 132 in good yield with excellent diastereoselectivity. the treatment of cis-acid 132 with thionyl chloride resulted in conversion to the acid chloride, dihydrogenation, and intramolecular friedel-crafts cyclization to provide the indenoisoquinoline ester 133 (nguyen et al., 2015). the ester 133 was then subjected to hydrolysis by sodium hydroxide in meoh/h2o (1:1) at 60°c to afford indenoisoquinoline acetic acid 134 in good yield. similary, the indenoisoquinoline acetic acids containing methoxy group in d ring were synthesized by a procedure as illustrated in scheme 24 (kohlhagen et al. 1998; thi et al. 2016). the cis-acid 136 reacted with thionyl chloride to provide a mixture of indenoisoquinoline esters 137 and 138, which were separated by column chromatography. the latter were then hydrolyzed by sodium hydroxide to afford acids 139 and 140, respectively (dung et al. 2019). scheme 23. synthesis of indenoisoquinoline acetic acid scheme 24. preparation of indenoisoquinoline acids 139 and 140. digafie zeleke and yadessa melaku ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 89 scheme 25. synthetic route for the preparation of indenoisoquinolines 140a-e. a group of indenoisoquinolines containing carboxylic acid functionalized groups were also synthesized starting from indenobenzopyran 105 using the same protocol (scheme 25) (dung et al., 2019). 2.6.1. cytotoxicity of 134, 139, 140 and 142a-e all the synthesized compounds were subjected to in vitro biological assessment against two human cancer cell lines (kb, epidermoid carcinoma; hepg2, hepatoma carcinoma) and ellipticine was as positive control. the results revealed that compounds constituting carboxylic acid groups on ring d (compounds 142a-e) displayed moderate cytotoxic activity against kb cell line and high activity against hepg2 cell line with ic50 values ranging from 10 to 32 μm with compound 142c being the most active to kb and hepg2 cell lines (ic50 value of 4.55 and 10.46 μm, respectively). however, the presence of the methylenedioxy or methoxy group on dring of indenoisoquinoline scaffold decreased the observed cytotoxicity activity. 4. conclusion a new class of topisomerase i inhibitors, indenoisoquinolines, emerged with the accidental isolation of the first lead indenoisoquinoline (nsc 314622) as a byproduct of nitidine chloride synthesis in 1978. since 1999 indenoisoquinolines were investigated extensively as a noncamptothecin topoisomerase i (top1) inhibitors which later on succeeded to find the first lead indenoisoquinoline (nsc 314622) with prominent activity back in 1998. over the years several synthesis reports have been developed leading to synthesis of indenoisoquinolines scaffold and it was pointed out that incorporating electron-donating alkoxy substituents on the aand d-rings and including nitrogen hetrocycles on the nitrogen side chain of the lactam moeity of the core indenoisoquinolines improved cytotoxic properties. significant cytotoxicity was observed for 3-nitro indenoisoquinolines compared to their corresponding dimethoxy analogues, in the synthesis reports of 9-hydroxy-8-methoxy series, worth mentioning among the recent achivements in the synthesis reports of the scaffold. the 7azaindenoisoquinoline derivatives bearing a 3-nitro group and 9-methoxy group were able to partially overcome resistance in several drug-resistant cell lines, and they were not substrates for the abcb1 drug efflux transporter. on comparative basis, 3-flourinated or 3chlorinated indenoisoquinolines were found to be safer and better topoisomerase i inhibitors than their respectiive 3-nitro analogs with the most active being the one having immidazole ring on the nitogen side chain of the lactam moeity. incorporating carboxylic acid moeity in the n-lactam side chain of 3-flourinated indenoisoquinolines afforded compound 142c with significant activity towards kb and hepg2 cell lines (ic50 value of 4.55 and 10.46 μm, respectively). in this review efforts have been made to recap the synthetic methods, reactions and the biological results of various indenoisoquinoline derivatives during 2015-2020. in conclusion, through optimization of various substuents of indenoisoquinoline scaffold, there seems to be a great chance to develop more effective anticancer drugs in addition to those within various stages of clinical trials. finally we recommended additional research to be conducted particularly on flouro and chloro indenoisoquinoline analogs which are promising to develop safe anticancer drug candidates. reference alley, michael c., dominic a. scudiero, anne monks, miriam hursey, maciej j. czerwinski, donald l. fine, betty j. abbott, joseph g. mayo, robert shoemaker, and michael r. boyd. 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(2005). “bioreduction activated prodrugs of camptothecin: molecular design, synthesis, activation mechanism and hypoxia selective cytotoxicity.” organic and biomolecular chemistry 3(10):1905–10. 61 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper mobile banking technology in ethiopia: adoption and implication for financial service inclusion birku reta entele adama science and technology university (astu), school of humanities and social sciences, economics program, adama, ethiopia, e-mail: birku200@gmail.com abstract the purpose of this study is to investigate the perceived factors that hinder mobile banking adoption by using a survey data and forecast its adoption rate using a secondary data from the national bank of ethiopia. the survey data was collected randomly from 100 respondents who have bank account and visits the bank in march 2018 and the secondary data time span was from 2010 to 2018. to realize the objective, the study adopts innovation diffusion theory and structural equation modelling for adoption. the study result reveals that, the perceived relative advantage of mobile banking, the perceived complexity of mobile banking usage, observability, trialability, perceived analog complement and trust on provider of mobile banking services, are found to be significant in influencing the decision to adopt mobile banking technology in ethiopia. in addition, the forecasted cumulative mobile banking users for the coming seven years i.e. by 2025 will be 2.3 million users with 1.27% penetration rate. some of the policy implications are that; banks (both public plus private) has to promote and create awareness via explaining relative advantage of mobile banking adoption compared to other banking channels, create trust building campaign on mobile banking providers, improves analog complement such as mobile phone service language, and other regulations. lastly, the concerned body such as banking industry shall provide some incentive which favor mobile banking adoption, at least up to some minimum threshold level, which can sustain adoption rate and increase banking service inclusion for those who are traditionally banked and unbanked. keywords: mobile banking; adoption; financial service inclusion; ethiopia. 1. introduction the evolution of information technology is changing the future of banking services, marketing and business tactics (muche beza, 2010). now a days, the adoption of electronic banking become common as a channel of banking services because of the quick advancement in information technology (it) and strong competition of banking market. however, of the current estimated over seven billion global population, 2.5 billion do not have access to bank services, whereas five billion have a mobile phone subscription1. thus, mobile banking technology is expected to fill the gaps, particularly, in developing market where an estimated 1.7 billion 1 https://www.ericsson.com › mobility-report. people have access to mobile phones but have no bank account globally (world bank group, 2013). this is a window of opportunities for mobile network operators (mno) for bridging the banking services with mobile phone users according to each countries interest and policies. furthermore, this technology contributes for increasing efficiency, bringing inclusions, which are the current agendas of digital dividends. nevertheless, in developing markets still the dominant transaction such as cash transfer, public utility payments, microloans and savings, insurance and cash deposit and withdrawal takes place by the traditional http://www.ejssd.astu.edu/ birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 62 means via agents/bank branches. to overcome the inefficiency and accessibility of banking services, adopting mobile banking technology could reduce the extent of the problem. mobile banking refers to using mobile devices to provide financial information, communication and transactions to customers such as checking account balances, transferring funds and accessing other banking products and services from anywhere, at any time (ensor et al., 2012). mobile banking reduces cost of banking services, including trip cost, time, and all opportunity cost of going to banking. in addition, its convenience, boundless in time and location as long as mobile network services are available, customers can make mobile banking which is potentially fit to solve the rural community’s banking problem in developing countries (mlitwa and tshetsha, 2012). for instance, in kenya, according to world development report (2016), in 2013, transaction of 21.9 billion usa dollars, which is small less than half of kenya’s gross domestic product (gdp), were conducted on mobile devices (world bank group, 2016). many articles has been published on the issues regard to mobile banking adoption in different countries, but not in ethiopia as far as the researcher knowledge is concerned. because of the fact that technology adoption is typical to the societal perspectives, norms and cultures and economic factors, it would be insightful to conduct this study in ethiopia context. study by donovan (2012) shows that mobile payment has fully transformed the economic activities since all sectors including health care institutions, whole sellers, agriculture and other sectors have already adopted and using it in kenya. in 2014, in kenya about more than 110 mobile money systems have been working, with more than 40 million users. one of the most well-known is m-pesa, which is now operational in more than five countries in east africa. the study by orotin et.al. (2014) reveled the contributions of mobile money towards the developments of market system in uganda and they investigated that the interoperability of telecom and banking sector has significant potential for inclusiveness to banking services. the main result of this study was that mobile money has important contributions for the users and for market modernization. the main services used through mobile banking are money transfer and more than two million customers who were previously unbanked are now accessing banking services using their mobile phones. study by mlitwa and tshetsha (2012) focused on adoption of cell-phone banking among low-income communities in rural areas of south africa emphasizing mobile banking may require more than access. this is because of the fact that many rural community in developing country needs to have awareness and willingness about the technology before decision to use them. furthermore, issues of trust of the provider were also one important factor for not using mobile phone banking in south africa. study by al-jabri and sohail (2012) has investigated mobile banking adoption in saudi arabia focusing on measuring mobile banking users’ satisfaction. according to this study, factors such as relative advantage, compatibility, and observability have positive impact on adoption whereas perceived risk has a negative impact on adoption. study by yu (2012) investigated factors affecting individual decision to adopt mobile banking in taiwan and according to his survey result social influence, perceived financial cost, performance expectancy, and perceived credibility are main significant factors influencing individual to adopt mobile banking services. study by yee-loong chong et al. (2010) focused on online banking adoption in vietnam using technology acceptance model. according to his study factors such as perceived usefulness, subsidy and trust on providers have positive impact on intention to use online banking in vietnam. in contrary to the concept of technology acceptance model, the perceived ease of use factor was not as such important according to the result of this study. another study by aboelmaged and gebba (2013) has investigated on mobile banking adoption using the technology adoption model and investigates that the perceived usefulness, value of the technology, easy-ofuse, image towards the technology, self-efficacy, and credibility are found to be important in affecting intentions to mobile banking usage. however, in the case of ethiopia even, the traditional banking service penetration is very low and the rural community near to 80 percent of the total inhabitants has birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 63 no good access to banking services. the bank penetration ratio according to 2017 financial access data tabulated in table 1. table 1: bank penetration rate (source: demirguc-kunt et al., 2017) country branches per 100,000 adults ratio of 1 bank to adults kenya 4.38 1: 22,831 ethiopia 1.39 1:37,500 south africa 8.0 1:12,500 korea 12.27 1:8,150 with the ratio of one bank to 37,500 populations, ethiopia has the least bank penetration and because of this fact, citizens are using traditional way of exchange activities with high opportunity cost. the status of mobile banking at africa level has been increasing and by the year 2017, it was around 12%. however, the share of ethiopia is extremely low as the country is lately established regulation of mobile banking in 2013. since, then onwards the banks and micro finance institutions (mfis) has been promoting to offer financial services through mobile phones and agents2 (villasenor et al., 2015). after a year in 2014/15, there were only two mobile money deployment in ethiopia those are m. birr and hello cash mobile money. based on the data from national bank of ethiopia (nbe) in 20173, the mobile penetration rate reached 51.2%. however, of this mobile subscriber, only 0.9% are mobile banking service users. the percentage of mobile banking users to total mobile subscribers and total population is 0.9% and 0.4% respectively implying that mobile banking service is at infant stage. on the other hand, the total bank to population ratio shows that large number of populations mainly in the rural areas are deprived of access to banking. hence, with the help of ict convergence, mobile banking could able to increase banking penetration with more access to financial services particularly for rural communities. therefore, in order to update banking service inclusion, there is a need to study mobile banking adoption behavior of service users in ethiopia. therefore, the general objective of this study is to 2 in 2013, the government has approved a mobile and agent banking regulatory framework to permit banks and mfis to offer financial services through mobile phones and agents 3 https://www.nbe.gov.et pdf › annual bulletin. explore perceived factors that prohibit the mobile banking adoption rate and limits its digital dividends in ethiopia4.the specific objectives are (1) to identify perceived factors prohibiting mobile banking adoption, (2) to estimate and forecast adoption rate of mobile banking in ethiopia, (3) to draw relevant policy input and implication. figure 1: mobile convergence with banking services 2. 2. methodology 2.1. source of the data the study uses both mini survey and secondary data in order to reinforce and strengthen the finding of this work. with regard to the primary mini survey data, the study used both self-administered and structured survey questionnaires exclusively focuses on those who have bank account but not using mobile banking services yet by the time of survey in adama and addis ababa cities. two banks i.e. commercial bank of ethiopia and awash international bank, was purposively identified and their customers who were voluntarily to respond to the survey were made to fill the questionnaires. the intention was that the commercial bank of ethiopia shall represent the public banks with all its attributes and the awash international bank was assumed to represent the private banks along with its attributes. the data was collected for one-month duration in march 2017, from customers who were randomly visiting the banks during that specific month. out of 160 total responses, finally only 100 respondents data were used for analysis purposes, while the remaining 60% were voided due to missing element and incomplete response. with regard to the secondary data, it is an aggregate country level mobile 4 internet adoption lags behind considerably: only 31 percent of the population in developing countries had access in 2014, against 80 percent in high-income countries. in ethiopia, internet penetration is 11.5% but mobile banking services can be offered with mobile network technology services without internet for the users. https://www.nbe.gov.et/ birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 64 banking subscription data obtained from the national bank of ethiopia. the data was from 2010 to 2018 (a nine-year consecutive series data). the data from the survey is used to estimate factor analysis for mobile banking service adoption whereas data from nbe used to forecast the diffusion of mobile banking service technology in ethiopia. 2.2. method of analysis the study adopts innovation diffusion model of rogers (2003) and then conduct factor analysis using structural equation modelling (sem) for identifying perceived factors that hinder mobile banking service adoption rate. to explore the diffusion of mobile banking adoption rate, the study uses bass diffusion model and lastly compare its result with the gompertz and logistic diffusion model. 2.2.1. models for technology adoption among many theories and models for innovation adoptions such as innovations diffusion theory (idt) by rogers (2003), theory of reasoned action (tra) by ajzen and fish bein, (2007), theory of planned behavior (tpb) by ajzen, (2011) and many more, this study adopts the innovation diffusion theory of rogers 2003. according to rogers’s model, the new technology adoption is influenced by perceived innovation characteristics such as relative advantage, compatibility, complexity, observability, and trialability. except from the complexity, all others have positive impact on technology adoption. apart from rogers, all the others theory of technology adoption is based on social psychology theories. however in this study, the rogers (2003) innovation adoption theory, which is defined adoption as a decision to make full use of an innovation, is used. because mobile banking services particularly from the consumer perspective is, an extension of new service technology use, which is directly leads to benefit cost evaluation (relative advantage as rogers call) compared to other alternatives. therefore, this study 5varimax is an orthogonal rotation method (that produces independent factors which means no multicollinearity) that minimizes the number of variables that have high loadings on each factor. 6 the other method is principal axis factoring, also called common factor analysis, or principal factor analysis. although mathematically very similar aims to investigate the perceived factors that prohibit the adoption of mobile banking services in ethiopia. 2.2.2. structural equation modeling (sem) method this model is a multivariate statistical analysis, which includes both factors analysis and multiple regression analysis together. it is mainly used to analyze the structural relationship between measured variables and latent constructs (blunch, 2015). hence, this study uses structural equation modelling to estimate mobile banking adoption rate. to check the reliability and validity of the measurement of the instrument this study employed kmo test and cronbach alpha respectively (krishnan, 2011). accordingly, the conceptual framework of the model is as shown in figure 25. this model have 7 component (latent) variables and 25 manifest item variables which measures each of these components. then, to conduct factor analysis, this study uses principal components (pca) extraction method, which is superior over the other extraction methods in terms of identifying uncorrelated linear combinations6. furthermore, pca extract components based on their variances according to descending order and also used when the correlation matrix is singular7. to check reliability of the items for each factors the study uses cronbach’s coefficient of reliability i.e. >=0.7(from different literature) and to check for validity, the kaisermeyer-olkin (kmo) test should be greater than 0.50 (hair et al. 1998). the factor analysis is conducted using spss and amos statistical software packages. the following hypothesis is tested by factor analysis. h1: perceived relative advantage of mobile banking has significant positive effect on intention to adopt mobile banking technology h2: perceived complexity to use mobile banking has significant negative effect on intention to adopt mobile banking technology h3: perceived compatibility of mobile banking has significant positive effect on intention to adopt mobile banking technology to principal components, it is interpreted as that principal axis that identifies the latent constructs behind the observations, whereas principal component identifies similar groups of variables. 7 http://www.statisticssolutions.com/factor-analysis-2/ http://www.statisticssolutions.com/factor-analysis-2/ birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 65 h4: perceived observability of mobile banking has significant positive effect on intention to adopt mobile banking technology h5: perceived analog complement for mobile banking has significant positive effect on intention to adopt mobile banking technology h6: perceived trust on provider of mobile banking has significant positive effect on intention to adopt mobile banking technology h7: trialability of mobile banking has significant positive effect on intention to adopt mobile banking services. figure 2: framework adopted from the unified theory of acceptance and use of technology (utaut) (venkatesh et al., 2003) 2.2.3. bass diffusion model to forecast the mobile banking adoption rate in ethiopia, the study uses bass diffusion model that is widely applied on new-product diffusion model. the bass model is derived from the hazard function concept that “the portion of the potential market that adopts at t given that they have not yet adopted is equal to a linear function of previous adopters" (bass, 1969). mathematically, using hazard function ( ) [ ( )] 1 ( ) f t q p a t f t m    (1) in the above equation, t represents the time at which technology is introduced and is assumed to be nonnegative. hence the technology diffusion bass model is framed as a fraction of adoption rate is: ( ) (t) ( ) 1 1 ( / ) e p q t p q t e f q p        (2) after rearranging the above equation the study estimate the bass model using data fit statistical software as below equation. ( ) ( ) ( ) 1 * 1 ( / ) e p q t t p q t e y m q p        (3) where,  m potential market (the ultimate number of adopters)  p – innovation coefficient birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 66  q – imitation coefficient.  a (t)-shows adopters at time t.  y-adoption rate 3. results and discussion 3.1. descriptive statistics of the total respondents majorities are male which accounts about 82 % and the remaining 18 % respondents are female. majority of the respondents are between 3140 years old age, majority of respondents income is less than 500$ per month and other descriptive statistics are as below table 2. 3.2. factor analysis before conducting factor analysis validity and reliability, tests should be examined and accordingly validity of the samples is tested by kmo and bartlett’s test as below table 3. to identify the maximum length of components in the factor analysis, the study used eigen values and the results are shown by descending order of their variance. the cut point is at the point for which eigen value is greater or equal to one. the cumulative total variance explained by the components up to the seventh is 80.085% (table 4). table 2: descriptive statistics variable frequency percentage gender female male 18 82 18.0 82.0 age of respondent in years less than 20 21-30 31-40 41-50 greater than 50 6 23 58 11 2 6.0 23.0 58.0 11.0 2.0 highest level of education less /equal to high school bachelor diploma master phd or above 17 9 7 51 16 17.0 9.0 7.0 51.0 16.0 job of respondents gov't employee no job private company employee self-employee 74 8 2 16 74.0 8.0 2.0 16.0 monthly income level of respondents($ ) 3001 on wards 2001-3000 1001-2000 501-1000 less than 500 2 2 6 16 74 2.0 2.0 6.0 15.0 74.0 table 3: kmo and bartlett's test kaiser-meyer-olkin measure of sampling adequacy. .515 bartlett's test of sphericity approx. chi-square 1020.929 df 300 sig. .000 to confirm the validity and reliability of each variable for each component is summarized standardized loading factor and cronbach alpha for reliability test (table 5). birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 67 table 4: total variance explained (extraction method: principal component analysis) table 5. validity and reliability test latent constructs indicators standardized loading reliability(ave,sc) relative advantage (pra) pra1 pra2 pra3 pra4 pra5 .724 .669 .776 .844 .834 n items =5 cronbach’s = .818 ave= 1.330 scr=-.867 perceived complexity(pcx) pcx1 pcx2 pcx3 .828 .784 .679 n items: 3 cronbach’s = .876 ave=71.424 scr=0.621 trialability tra1 tra2 tra3 .889 .752 .776 n items: 3 cronbach’s = .916 ave=1.063 scr=0.616 perceived compatibility(pcb) pcb1 pcb2 pcb3 pcb4 .696 .870 .702 .808 n items: 4 cronbach’s = .842 ave=0.535 scr=0.846 perceived observability (pobs) pobs1 pobs2 pobs3 pobs4 .841 .722 .819 .697 n items: 4 cronbach’s = .704 ave=143.970 scr=-0.754 trust on provider(top) top1 top2 top3 .721 .686 .780 n items: 3 cronbach’s = .798 ave=125.453 scr=0.765 perceived analog complement(pac) pac1 pac2 pac3 .706 .804 .754 n items: 3 cronbach’s = .742 ave=33.952 scr=-0.765 3.3. estimation results the regression coefficient of each component on intention for adoption of mobile banking is run by amos and its result is as below figure 3. according to the below estimation six components are found to be significant in influencing the intention of mobile banking adoption except the compatibility component. to check the fitness of the model and other criteria, here below (table 6) are some of the indicators. component initial eigen values rotation sums of squared loadings total % of variance cumulative % total % of variance cumulative % 1 6.933 27.731 27.731 3.439 13.755 13.755 2 3.252 13.006 40.737 3.066 12.263 26.018 3 2.817 11.268 52.005 2.903 11.612 37.629 4 2.639 10.558 62.563 2.880 11.521 49.150 5 1.511 6.044 68.607 2.518 10.072 59.222 6 1.184 4.737 73.344 2.252 9.009 68.231 7 1.005 3.741 80.085 2.213 8.854 80.085 birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 68 to check the fitness of the estimated model the result of rmr and gfi indexes are used. hence, accordingly the gfi (fitness index) shows that 80.1% of the model is explained by these components, which implies that the model is relatively fitted well. figure 3: estimation result of mobile banking adoption table 6: regression weights: (mobile banking adoption model), rmar and gfi index attributes estimate c.r. p rmr, gfi compatibility 0.016 3.752 .004 default model=0.679 saturated model=0.000 independence model 0.325 default model=0.801 saturated model=0.900 independence model=0.307 relative advantage 0.788 3.590 *** complexity -0.816 3.752 *** trust on provider 0.692 6.103 *** observability 0.997 7.701 *** trialability 0.839 5.319 *** perceived analog complement 0.648 3.365 *** 3.4. discussion as per the research objective, perceived factors influencing mobile banking adoption are identified with limited information (small sample size). accordingly all the research hypothesis is tested where some are confirmed as per hypothesized above and others are rejected. the discussion and analysis for each of the hypotheses is made with the understandings of all other things are assumed constant. h1: the more perceived relative advantage of mobile banking the more intention to adopt mobile banking technology the first hypothesis is, perceived relative advantage of mobile banking, expected to have positively birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 69 influencing mobile banking adoption. the result confirms this hypothesis and even significant at 5% significance level. the more they perceive relative advantage compared to others alternatives, the more they have intention to adopt mobile banking technology. this result is similar with other research finding such as study on online banking in vietnam by yee-loong chong et al. (2010). hence, the main point is that consumers are willing to adopt mobile banking when they realize the advantages of it compared to other channel of banking. therefore banks and other concerned body should further investigates the types of feature which current bank users find useful or they will find useful and promote such features to encourage more customers to adopt mobile banking. h2: the more perceived complexity to use mobile banking, the less intention to adopt mobile banking technology. this hypothesis is confirmed by the estimated result. the result shows negative significant value, which implies that, the more perceived complexity of mobile banking, the less intention to adopt this technology particularly for those who are illiterate, assuming other things are constant. h3: the more perceived compatibility of mobile banking, the more intention to adopt mobile banking technology. the result of this hypothesis is insignificant which, perhaps, implies compatibility is not significantly influencing a decision to adopt mobile banking technology. for the respondents the compatibility is not a big deal to influence the decision to adopt mobile banking service technology or not. h4: the more perceived observability of mobile banking, the more intention to adopt mobile banking technology according to the survey result, the value for component observability is positive and significant. this implies people adopt mobile banking technology when observe real impact of it than otherwise. this result is consistent with many other studies such as (yee-loong chong et al. 2010; tan et al. 2010). h5: the more perceived presence of analog complement for mobile banking the more intention to adopt mobile banking this hypothesis is confirmed according to the finding of this study. that means the more people perceive presence of analog complement, the more they have intention to adopt mobile banking, assuming other things are constant. this implies that even in less developed countries people worry the problem of analog complement, legality issues to make decision to adopt technology. the more diversified mobile banking language services, the more people intendeds to adopt the services. h6: the more perceived trust on provider of mobile banking the more intention to adopt mobile banking technology this latent component has also positive and significant influence on intention to adopt mobile banking. that means the more trust on mobile banking service provider the more intention to adopt this services, assuming other things are constant. this result is consistent with the finding of study in vietnam on ‘online banking’ by yee-loong chong et al. (2010). according to wang and barnes (2007), it is possible to build trust strategies through advertising campaign, privacy guarantee, company guarantee policy and different statement. therefore, banking in ethiopia is also required to use these types of trust building campaign if they want to promote mobile banking adoption. h7: the more trialability of mobile banking, the more intention to adopt mobile banking services the study result confirms this hypothesis. the result shows that as more perceived trialability of mobile banking, the more intention to adopt mobile banking service. therefore, to increase penetration of mobile banking service in the country, banking sectors and the governments need to do a lot on awareness creation on advantage of using mobile banking, easiness of using mobile banking, trust and security of mobile banking providers, interoperability of banking and telecom sector, compatibility of mobile banking and other more issues. 3.5. diffusion of mobile banking technology the study forecasted the diffusion of mobile banking adoption rate using the bass nonlinear regression (nls) birku reta . ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 70 model. the numerical value of diffusion parameters and performance test results are listed in table 7. table 7: nls diffusion of mobile banking adoption in ethiopia by 2025 parameter estimation bass model gompertz model logistic model p 0.02 3.21 3.51 q 0.36 0.88 -0.46 𝑹𝟐 0.974 0.965 0.968 adj.𝑹𝟐 0.9702 0.963 0.964 forecasted potential subscriptionsm (thousand) by 2025 2268.22 1206.12 1217.20 forecasted penetration rates considering populations growth rate 2.6%, csa (2015) 1.27% 1.21% 1.22% the estimated results show that the bass estimated model is relatively better than the other two models. the coefficient of innovation for mobile banking service is 0.02 whereas the imitation coefficient is 0.36, which implies that the diffusion rate is occurring more because of internal influence and word of mouth. that means the more people talking about a service, the more other people in the social system will adopt. the overall goodness of model is 97.02% as explained by adjusted r2. the forecasted subscription of mobile banking by 2025 is about 2.3 million users and the penetration rate is 1.27% considering the population growth rate, which is 2.6%, according to the central statistical agency of ethiopia (2015) assuming other things are constant. 4. conclusion and implication the study has identified the perceived factors that hinder mobile banking adoption with their level of extent using econometrics estimation. those are the perceived relative advantage of mobile banking compared to other alternatives, the perceived complexity of mobile banking usage, observability, trialability, perceived analog complement and trust on provider of mobile banking services. except compatibility construct, all the other components are found to be significant in influencing the decision to make mobile banking adoption. concerning the diffusion of mobile banking adoption the bass model is used to forecast the diffusion until 2025. accordingly, the estimated mobile banking adopters for the coming seven years i.e. by 2025 in ethiopia will be about 2.3 million users with 1.27% penetration rate. this shows that ethiopia will have the lowest mobile banking penetration by 2025 if not take any other measures such as more awareness creation and different incentives that favor mobile banking adoption. based up on the findings of the study, some of the policy input and implications are as follows. the banking industry or government has a lot to do with regard to awareness creation, explaining relative advantage of mobile banking technology relatively to other banking channels, on trust building on mobile banking providers, on improving analog complement such as mobile phone service language, and other regulations. furthermore, the concerned body such as banking industry shall provide some incentive which favor mobile banking adoption, at least up to some minimum threshold level, which can sustain adoption rate and increase banking service inclusion for those who are unbanked yet. finally, a few limitations in our approach that can be a future work for other researcher is that the study is limited to mini survey data during specific month in a year from two banks. however, the frequency and intensity of banking service usage might fluctuates and vary across months or seasons and vary across banks to some extent. hence, having knowing this, the study suggest future research work that consider and relax this limitation. acknowledgement the study was supported by international it policy program (itpp) of seoul national university and adama science and technology university (astu). therefore, i would like to thank itpp (snu) and astu for the invaluable support. reference aboelmaged, m. and gebba, t. r. 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(2012). factors affecting individuals to adopt mobile banking: empirical evidence from the utaut model. journal of electronic commerce research, 13(2), 104. 65 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper antibacterial activities of the cuo/zno nanocomposite grown on silica extracted from bagasse ash yirgalem negash, birhanu tolosa, tegene bantewesen, gebisa bekele department of material science and engineering, adama science & technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 07 september 2020 received in revised form 02 december 2020 accepted 14 december 2020 nano-scaled zinc oxide and copper oxide semiconductors have been widely used as antibacterial agents because of low cost and non-toxicity, but high agglomeration and high electron-holes recombination rates hinder their performances. in this work, we synthesized silica-supported cuo/zno and cuo/zno bare nanocomposites by the sol-gel technique. the antibacterial activities of both nanocomposites have compared on gram-negative (e. coli) and gram-positive (s. aura) bacteria. the average crystal sizes of cuo/zno bare is 16.3 nm, and silica-supported cuo/zno is 29.1 nm as calculated from xrd data. moreover, sem results showed that there was no agglomeration in silica-supported cuo/zno due to the presence of silica. when antibacterial activities of both nanocomposites were tested by using the agar diffusion method, silica-supported cuo/zno showed an inhibition zone of 51% for staphylococcus aureus and 53% for escherichia coli compared with that of cuo/zno bare. therefore, silica-supported cuo/zno nanocomposite is a promising antibacterial agent because of its low cost, non-toxicity, and good antibacterial properties. keywords: sugarcane bagasse ash sol-gel cuo/zno silica antibacterial activities 1. introduction nano-scaled semiconductors are materials with a size in the range of 1-100 nm, narrow size distribution, high agglomeration, and a high dispersion (lines, 2008). due to such novel properties of nanomaterials, they are utilized in different applications such as wastewater treatment, paints, cosmetics displays, medicine, batteries, catalysis, gas sensor, food engineering, and agriculture (arivalagan et al., 2011). in developing countries like ethiopia, waste management practices are so poor that it is common to hear news about widespread of infectious diseases. for instance, ethiopia have a sufficient amount of water resources in east africa. the two sources of water in ethiopia are surface and subsurface water: surface water is around one hundred twenty-four billion cubic meters and  corresponding author, e-mail: gebisabek12@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.319 underground water is thirty million cubic meters (ademe et al., 2014). however, the water quality is deteriorated due to improper management of industrialization, urbanization, organic water pollutants, inorganic water pollutants, and agricultural waste (sharma et al., 2017; inyinbor et al., 2018; mia et al., 2019). drinking such contaminated water causes diseases like cholera, dracunculiasis, typhoid fever, diarrhea, ulcers, hepatitis, and arsenicosis (fazal-urrehman, 2019; hopkins et al., 2019). starting from the discovery of penicillin in 1928, a complete transformation in global health and life expectancy has been observed. but, the appearance of antibiotics resistance bacteria has awaken the research communities to figure out antibacterial agents that able http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021................ yirgalem negash et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 66 to treat antibiotic resistance bacteria. due to the evolution of drug resistance in pathogenic bacteria, the normally treated illnesses yesterday are becoming fatal today. to tackle the challenges that have been caused by antibiotic resistance bacteria, several schemes and approaches have proposed (jan et al., 2019; manyasree et al., 2017) like natural extracts (shweta et al., 2015), adsorption (ademiluyi et al., 2009), ozonization (nabi et al., 2006), photocatalysis (claudia et al., 2019), and membrane filtration (zioui.et al., 2015). among these methods, photocatalysis is easy to use, eco-friendly, and inexpensive. photocatalysis mainly depends on the choice of metal oxide semiconductor that has the capability of creating electron-hole pair which generates free radicals to inhibit bacteria and degradation of dye (sun et al., 2009). nano-scaled metal oxide semiconductors used as photocatalyst are cuo (manyasree et al., 2017), zno (sun et al., 2009), wo3 (nandiyanto et al., 2017), mgo (bandara et al: 2004) tio2 (bandara et al: 2004) and fe2o3 (ahmmad et al., 2013). zno is an n-type semiconductor, utilized broadly due to its high photocatalytic activity, non-toxic nature, inexpensive, hydrophilic property, excellent chemical and mechanical stability (azmina et al., 2017). however, limitations of zno are confinement of zno, agglomeration, photo corrosion, the large bandgap energy (3.2 ev) (sherry et al., 2015; saravanakkumar et al., 2019). cuo is a p-type semiconductor, narrow band gap energy (1.2 ev), low-electrical resistance values, inexpensive, and non-toxic. but, it has limitations like low photocatalytic activity that leads to the deficiency of charge transport inside cuo (shirzadi et al., 2016; anandan et al., 2007). thus, cuo/zno nano-scaled semiconductor reduces the rate of electron-hole recombination and increases the lifetime of nanocomposites (sakib et al., 2019; widiarti et al., 2017), which leads to better photocalytic properties. the main challenge of cuo/zno nanocomposite is agglomeration, poor catalytic efficiency, and difficulty in separation of nanocomposite from solution after use (azmina et al., 2017), (he et al., 2019). songfa et al. (2020) synthesized mesoporous silica supported cuzno and they showed that antibacterial activities of mesoporous silica supported cuzno were much better compared to mesoporous silica supported cuo and zno (songfa et al., 2020) because of cu doped zno have smaller band gap than zno, which result in reducing recombination rate of electron-holes that were formed during irradiation of visible light. however, still, the recombination rate of electrons-holes were there because of the electrons in conduction band and holes in valence band of cu doped zno. in addition to this, they synthesized the mesoporour silica particles by hydrothermal method which is very expensive and time consuming method. in this work, cuo-zno heterojection was synthesized on crystalline silica extracted from bagasse ashes by sol-gel method. here, the combination of the cuo-zno doping, or cu substitute zn in zno or vice versa process may happen in cuo, which leads to reduced recombination rate. the bagasse ashes are low cost, easily synthesized, and non-toxic. the synthesized silica with porosity, unstable surface, and a high adsorption capacity makes them suitable for the growth of nanocomposite and water purification. the porosity nature of silica provides an excellent attachment and adsorption abilities to the nanocomposite (azmina et al., 2017). therefore, we found that antibacterial activities of silica-supported cuo/zno are better than cuo/zno nanocomposites grown without silica substrate. 2. experimental methods 2.1. materials in this research the raw materials consist of sugarcane bagasse ash (sba) obtained from wonji shewa sugar factory (ethiopia), zinc(ii) acetate dihydrate (zn(ch3coo)2.2h2o) 98% (merck), copper(ii) sulfate pentahydrate (cuso4.5h2o) 98% (merck), ethanol 98%, sodium hydroxide (naoh) (merck), filter paper, ethylene glycol (ch2oh)2), citric acid 10% (c6h8o7), hydrochloric acid (hcl), dimethylsulfoxide (dmso) and distilled (di) water. chemicals used in this experiment were analytical grade and used without extra purification. 2.2. preparation of silica from sugarcane bagasse ash the sba was calcined in the furnace for 4hrs at 1100°c to remove carbon. then it was cooled down up to room temperature before taking it out. after that, the ash was washed with 1m hcl to remove extractive minerals and iron composition. the cleaned products were filtered with filter paper named as what-man no 41. then 20 g solid was treated with 200 ml of 3m naoh under heating and stirring at 100°c for 90 min. yirgalem negash et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 67 the mixture was cooled and filtered to remove solid residues. the obtained sodium silicate solution was precipitated using a 1m hcl solution until ph 7 and kept for 24 hrs at 25ºc for silica to completely solidify. the slurry was filtered and washed with di water until it reached neutral ph. the solids were dried using an oven at 100°c for 24 hrs (rahman et al., 2016; mengistu, 2018). 2.3. synthesis of cuo/zno grown on silica two gram of silica was added to 50 ml of distilled water, 50 ml ethylene glycol, and 8 ml of citric acid and stirred for 30 min. after that 10.649 g of zinc acetate was dissolved into 25 ml of di water and added to the previous solution drop by drop and stirred vigorously for 1 hr at room temperature. then, 2.66 g of cuso4.5h2o which dissolved in 25 ml di water was added again drop by drop and stirred at 60°c for 3 hrs. it was placed in a dark area for 48 hrs. then, washed with di water several times, and then washed with ethanol. finally, the gel was dried at 120°c followed by calcination at 500°c for 4 hrs. (widiarti et al., 2017). the synthesizing procedures of the bare cuo/zno were the same as that of the synthesizing procedures of silica-supported cuo/zno except in synthesizing of silica-supported cuo/zno need the addition of silica. 3. results and discussions 3.1. xrd analysis x-ray diffraction (xrd) was used to analyze patterns of cuo/zno bare and cuo/zno grown on crystalline silica as shown on figure 1. figure 1: x-ray diffractograms of cuo/zno bare, silica-supported cuo/zno supported on silica and silica the diffraction peak obtained at 2θ=34.2◦, 35.7◦, 37◦, 38.9◦, 41.7◦, 48.7◦, 53.8◦, 58.4◦, 61.5◦ with miller indices, (110), (002), (111̅), (111), (200), (201̅), (020), (202), (113̅). the presence of cuo was identified by comparing with (jcpds card no. 48-1548) for 2θ values of 37◦ and 41.7◦ and with miller indices (111̅), and (200) (li, h, et al., 2016). the high intense peak observed in cuo/zno bare indicates high crystalline nature than cuo/zno silica supported. also sharp peaks at (002) and (111) show high crystalline nature of zno with hexagonal structure. the crystalline size was calculated from 2θ and fwhm of the (h k l) peaks using scherer’s relation as shown in equation 1 (hojabri, et al., 2014). d = kλ / β cos θ ……………. (1) where, d is crystallite size, k is shape factor has a typical value of about 0.9, λ is the x-ray wavelength with value 1.54060 nm and β is the line broadening at half the maximum intensity (fwhm), θ is the bragg angle. the calculated average crystallite size of the synthesized cuo/zno is less than 50 nm because smaller particle size has tremendous effect on the antibacterial activities. for instance, nandiyanto et al. (2017) reported that smaller crystallite size value has significant effect on the performance of nanocomposites (nandiyanto et al., 2017). in our case, the calculated average crystallite size of cuo/zno bare is 16.3 nm and cuo/zno grown on silica is 29.1 nm. even though, the size of silica supported cuo/zno is larger than bare cuo/zno, it show better antibacterial activities because it is free from agglomeration as it is confirmed by sem results. the reason why the xrd peak of silica did not appear in the silica-supported cuo/zno is due to the whole surface of silica is covered by cz nanocomposite. 3.2. fourier transform infrared spectroscopy (ftir) analysis when infrared light interacts with the substance chemical bonds will stretch, contract and bend. the functional group of samples was recorded beneath the infrared spectroscopy of the wavenumber of 500 cm-1 4000 cm-1. the functional group –oh of cuo/zno on silica and cuo/zno bare nanocomposites samples located at wide absorption peaks between 3280 cm-1 – 3650 cm-1 are as shown on figure 2. the presence of the -oh functional group indicates the existence of water absorption on the surface of the yirgalem negash et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 68 nanocomposite (saravanak, et al., 2018). the c=o functional group observed at the wavenumber 1650 cm1, c-o at 1123 cm-1 and c-h at 2929 cm-1 for both samples. the appearance of c=o, c-o and c-h functional groups is due to the unsuitable decomposition of acetate functional groups present in zno precursor. the peaks observed at 790 cm-1 may indicates si-o-si functional group exists due to silica used as a substrate in the cz synthesized. the absorption band of metal oxide was below 1000 cm-1 due to its inter-atomic vibrations. strong absorption band in the range 700 cm1 – 400 cm−1 assigned to cu-o stretching mode (qiu et al., 2020). generally, stretching of zn-o in the zno is between 400 cm-1 and 531 cm-1 which confirmed the wurtzite structure (widiarti et al., 2017). the absorption peak acquired at 482 cm-1 and 460 cm-1 for cuo/zno bare and cuo/zno grown on silica respectively shows the presence of zno (stretching zn-o). the absorption peak observed at 614 cm-1 and 545 cm-1 were indicating that the presence of cu-o stretching on cuo/zno bare, and cuo/zno on silica. slight shift in peak occurred in the case cuo is may be because of van der waals force of attraction between the cuo/zno and silica. 500 1000 1500 2000 2500 3000 3500 4000 30 40 50 60 70 80 90 100 t ra n s im it a n c e (a rb .u n it ) wavenumber(cm -1 ) oh c-hc=o c-o cuo cuo zno si-o-si cuo/zno bare cuo/zno on silica figure 2: ftir spectra of cuo/zno bare and cuo/zno on silica 3.3. scanning electron microscope analysis the surface morphology of cuo/zno bare and cuo/zno on silica were examined using scanning electron microscope (sem) and their corresponding edx are shown in figure 3. the sem image clearly displays high clusters of particles which leads to creation of agglomeration in cuo/zno bare. this may be due to addition of cuo to zno causes more attraction between particles (sajjad et al., 2018). in addition to this the surface energy of the particles forced them to stick together to gain stability (vuong et al., 2016). the morphology of cuo/zno on silica is modified because the silica substrate has uniform particle distribution and smooth surface. this allows cuo/zno grow easily and prevent agglomeration. the modification of morphology enriches cuo/zno to have more active sites for better antibacterial activity. here, edx showed that cz bare contains all expected elements and similarly, silica supported cz nanocomposites contains all excepted elements. in both nanocomposites, the impurities mo was detected. figure 3: sem image of (a) cuo/zno bare and its edx, (b) cuo/zno grown on silica and its edx a) ) b) ) yirgalem negash et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 69 300 400 500 600 700 800 0 5 10 15 20 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 ( f (r )h v )^ 2 hv(ev) cuo/zno bare cuo/zno on silica a b so r b a n c e (a r b .u n it ) wevelength(nm) 280nm 285nm cuo/zno bare cuo/zno on silica 3.4. ultraviolet-visible spectroscopy analysis uv-vis absorption spectra and kubelka munk plot of band gap estimation of cuo-zno bare and silicasupported cuo/zno nanocomposite were measured as shown in figure 4. the absorbance measurements were done by using uv-visible spectroscopy which consists of a light source, collimator, monochromator, and wave length selector, cuvette for sample solution, a photoelectric detector and a digital display. we dispersed our nanocomposite in dmso and spread them on thin film glass. the sample solution puts into cuvette first lens transmits a straight beam of light that passes through a monochromator to split it into several component wavelengths. then, a wavelength slit transmits only the desired wavelengths. after the desired range of wavelength of light passes through the solution of a sample in cuvette, the photometer detects the amount of photons that is absorbed and then absorbance versus wavelength data were displayed on pc. figure 4: uv-vis absorption spectra and the kubelka munk plot of band gap estimation as shown in figure 4, the absorption spectra of cuo/zno bare and silica supported cuo/zno are nearly the same because their difference is only supporting material i.e. silica has no contribution on the narrowing band gap of cuo/zno heterostructure. therefore, the band gap of the two materials is nearly the same, which leads absorption spectra of the two materials to have insignificant difference. from the kubelka munk plot, the band gap of the silica-supported cz and cz bare is nearly the same because of aforementioned reasons. therefore, the band gap of the two materials is nearly the same which lead to same absorption spectra for both nanocomposites. in fact, jianyu et al. (2015) reported that the maximum absorption wave length of cuo-zno nanocomposite is around 300 nm. thus, the calculated error bar for cz bare is 3.4% and 2.5% for silica supported cz. therefore, the maximum absorption wavelengths of cz bare and silica supported cz nearly the same as that reported by jianyu et.al. (2015).the maximum absorption wavelengths are 280nm and 285 nm for cuo/zno bare and silica-supported cuo/zno, respectively. enhancement of absorption in the uv region was observed in silica-supported cuo/zno than cuo/zno bare due to reflectance of uv light by silica in the silica-supported cuo/zno (azmina et al., 2017). in addition to this, the agglomeration of cuo/zno bare also responsible for the reduction of absorbance in cuo/zno bare due to agglomeration leads to large particle size, large particle size mean low particle concentration and low absorbance (goh et al., 2014). 3.5. antibacterial activity test the antibacterial test was conducted on both gramnegative (escherichia coli) bacteria and gram-positive (staphylococcus auras) bacteria. the cultural media of bacteria were prepared at adama science and technology university, biology department. the antibacterial activity test was conducted by the agar well diffusion method. for 24 hrs bacteria were grown in a biochemical incubator. after that both types of bacteria were spread on the agar media by cotton. we measured our nanocomposite on two different weights starting from the most frequently used weight of 15 mg/ml and 20 mg/ml. the measured nanocomposites were dispersed in the dmso (dimethyl sulfoxide) for 30 min. then, three well were formed on the medium. the prepared nanocomposite solution was added in the drilled part of the media and incubated at 37°c for 24 hrs. the zone of inhibition was measured for 15 mg/ml nanocomposites after 24 hr as shown in table 1. however, we have faced difficulty on measuring the value of 20 mg/ml nanocomposite due to its high inhibition of the bacteria growth. from table 2, we conclude that the inhibition zone of nanocomposite is better in gram-positive (staphylococcus aureus) compared with gram-negative (escherichia coli) bacteria. this is because of gram-negative bacteria (escherichia coli) typically contain thin cell wall and outer membrane, a layer of the cytoplasmic membrane. yirgalem negash et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 70 table 1: zone of inhibition samples staphylococcus aureus escherichia coli cuo/zno bare cuo/zno grown on crystalline silica table 2: zone of inhibition values of measured after 24 hrs. samples staphylococcus aureus escherichia coli cuo/zno bare 25mm 15mm cuo/zno grown on crystalline silica 27mm 17.5mm this outer membrane resists certain drugs and antibiotics from penetrating the bacteria cell. grampositive bacteria contain a thick layer of the cell as well as a layer of the cytoplasmic membrane, which make gram-positive bacteria more susceptible to antibiotics than gram-negative bacteria (zeng et al., 2013).this is due to gram-positive bacteria had thick cell wall which leads to absorb nanocomposite highly compared to gram-negative bacteria (pasquet et al., 2014). antibacterial activity of cuo/zno nanocomposite depends on reactive oxygen species, cu2+and zn1+ released from the decomposition of cuo/zno and concentration of cuo/zno. we obtained enhanced antibacterial activity from cuo/zno grown on crystalline silica compared to cuo/zno bare nanocomposites. this is due to higher amount of reactive oxygen species (ros) such as superoxide radical anion (o-2), hydroxyl radical (•oh), hydrogen peroxide (h2o2). the reason why cz synthesized on silica substrate have high ros than cz bare is because of well dispersed states of cuo/zno nanocomposite, in other words, free from agglomeration. in fact, once the nanocomposite agglomerate, the surfaces at which electrons and dissolved oxygen joined was reduced, and vice versa for nanocomposites that are free from agglomeration. therefore, silica supported cuo/zno nanocomposite has higher free surfaces to generate the ros than cz bare. moreover, as jan et al. (2019) reported, adding cuo on zno introduce more surface defect on cuo/zno. the higher surface defect is related to a higher amount of reactive oxygen species (ros) which in turn leads to higher bacterial inhibition (jan et al., 2019). 4. conclusion in this research, cuo/zno bare and cuo/zno on silica were successfully synthesized via sol gel method and then characterized with xrd, sem, ftir, uv-vis spectroscope and agar well diffusion method. the average crystal sizes of cuo/zno bare is 16.3 nm, and silica-supported cuo/zno is 29.1 nm as calculated from xrd data. moreover, sem results showed that there was no agglomeration in silica-supported cuo/zno due yirgalem negash et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 71 to the presence of silica. similarly, ftir also revealed that values less than 1000 cm-1 show the presence of metal oxides. the absorption peaks are observed at 280 nm for cz-bare and 285 nm for cz supported on silica. the antibacterial activities of synthesized nanocomposites were investigated on e. coli and s aureus bacteria. when antibacterial activities of both nanocomposites were tested by using the agar well diffusion method, silica-supported cuo/zno showed an inhibit zone of 51% for staphylococcus aureus and 53% for escherichia coli compared with that of cuo/zno bare. therefore, silica-supported cuo/zno nanocomposite is a promising antibacterial agent because of its low cost, non-toxicity, and good antibacterial properties. acknowledgment the authors are grateful to the department of material science and engineering, adama science and technology university for support provided. reference ademe, a. s., & alemayehu, m. 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(2015). membrane technology for water treatment applications. international journal of chemical and environmental engineering, 6(3). 25 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper the application of brewery sludge for maize production bulti merga1,, muktar mohammed2, abdulatif ahmed1, mulatu wakgari1 1school of plant sciences, haramaya univesity; p. o. box 138, dire dawa, ethiopia 2college of natural resources and environmental science, oda bultum university; p.o. box 226, chiro, ethiopia article info abstract article history: received 27 july 2020 received in revised form 29 september 2020 accepted 10 october 2020 in this study, brewery sludge was evaluated in comparison with the recommended np mineral fertilizer rate to elucidate a potential source of nutrients for maize crop. randomized complete block design (rcbd) was laid out in three blocks at the experimental site. physicochemical properties of the experimental soil and brewery sludge (bs) were evaluated in the soil laboratory. the n content of the grain and straw samples were determined using the wet digestion method. heavy metals (fe, cu, zn, mn, cr, mo, co, pb, se, and cd) were extracted by dtpa extraction method and measured by atomic absorption spectrophotometer. the application of a 15 t ha-1 sludge rate showed the highest grain yield that exceeds the value recorded from np-treated and control plots by 3.15 t ha-1 and 4.42 t ha-1, respectively. similarly, the application of 12.5 t ha-1 sludge rate significantly increased the total nitrogen uptake of the crop (grain and straw) by 146.13% and 223.16% over the np and control plots, respectively. there was 93.23%, 57.14%, and 76.78% higher significant difference of total nitrogen, organic carbon, and available phosphorus (mg kg-1) in bs than the composition found in experimental soil before the application of treatments, respectively. the application of sludge maintained most of the heavy metal concentrations to the level of safety for health following the recommended ranges by world health organizations (who). in conclusion, future long-term study is required to elucidate the effect of the sludge on soil biology, the chemical property of soil (ph and salinity), and pathogen contaminations on soil and crop production. keywords: heavy metals maize yield brewery sludge reuse mineral fertilizer eastern ethiopia 1. introduction the brewing industry is one of the largest agricultural-based industries that produce a vast amount of residues every year. industrial waste is defined as an unwanted byproduct of industrial processes that includes mining and manufacturing activities. currently, a world concern is to find alternative options for disposal of untreated agro-industrial wastes rather than disposing of them through burning, unplanned landfilling, or releasing to a water body (okonko et al., 2009; sadh et al., 2018). in the majority of developing countries like ethiopia, agro-industry releases a tremendous amount of wastewater which is untreated,  corresponding author, e-mail: bultimerga@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.229 and its effluents are mostly released into water bodies and soils (ermias alayu and seyoum leta, 2020; temesgen oljira et al., 2017). disposal of industrial waste through landfilling is the primary causal agent for methane production which comes from the decomposition of organic matters in the anaerobic process (bailey, 2019). in addition to this, methane is considered as very short-lived gas but can cause long-lasting climate impact than co2 in thousand folds for more than two decades period. there is no question that sustainable brewery sludge management has a significant potential to mitigate climate change. http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021................ bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 26 currently, improper disposal of industrial waste, climate change, and unsustainable agricultural production are unsurpassable world problems (mbow et al., 2017; kumar et al., 2017). the residues of agro-industries that are disposed of spontaneously to the soil and water body have adverse effects on organisms and the environment (sadh et al., 2018). brewery sludge, as with any organic matter, improves soil fertility and can be used as an alternative way of reducing the cost of crop production. nowadays, the accumulations of heavy metals in the terrestrial ecosystem are changing the chemical properties and composition of the soil, which can cause a significant loss in the agricultural sector (satashiya, 2017). ermias alayu et al. (2018) conducted a field trial in amhara regional state, the northern part of ethiopia during the 2017 main cropping season on the farmers’ field under the normal rain-fed condition to evaluate the effects of bs and mineral fertilizer on maize production. results revealed that the addition of the sludge led to significant changes in soil ph reduction and soil electrical conductivity, total phosphorus, total nitrogen, and total potassium increment as compared to others and background concentration. hence, rather than improperly dumping industrial waste, the recycling of brewery sludge has many advantages; reduce greenhouse gases, control groundwater pollution, and protect humans from health hazards. furthermore, the utilization of industrial waste for crop production as input is environmentally safe, economically low cost and provides high essential elements for plant growth and development. maize can be consumed raw and in processed form by human beings and animals in addition to their advantages as raw materials in making beverages, ethanol, and starch in industries (ranum et al., 2014). soils are the heart of terrestrial ecosystems that help non-living things and living organisms to function as a source of the necessities for life. this paper evaluated and answered two questions: 1) can the reuse of brewery sludge be an alternative option that may replace mineral fertilizer in maize production? 2) is the application of bs to agricultural soil ecofriendly to reduce environmental pollution? 2. materials and methods 2.1. description of the brewing industry the brewery sludge was collected from harar brewing industry located at harari city, eastern ethiopia. the industry was established in 1984 and it produces both alcoholic (harar beer and hakim stout beer) and non-alcoholic (sofi beer) beverages. 2.2. description of the experimental site the collected brewery sludge in solid form was analyzed to evaluate their physicochemical properties at haramaya university soil laboratory, ethiopia. farmer’s field located in proximity to the brewing industry (sofi district) was used as an experimental farm during 2013/2014 under the rained condition to assess the effects of sludge on maize growth attributes and grain yield. the area is geographically located between latitude 09° 18′ 43′′ n and longitude 42° 07′ 23′′ e. it represents a medium altitude and moderate rainfall (850 mm/annum). 2.3. treatments, experimental design, and procedures in this study, seven rates of brewery sludge’s (0.0; 2.5; 5.0; 7.5; 10.0; 12.5 and 15.0 t ha-1) and a recommended rate of np mineral (92 kg n ha-1 and p 92 kg p2o5 ha -1) were used to evaluate their cost-benefit in maize crop production. improved maize variety, bh661, was used as an experimental crop at the spacing of 70 cm between rows and 25 cm between plants at the depth 7-10 cm. field plots (5 m × 6 m) were used for bs, commercial fertilizer (i.e., np), and control treatments for the study purpose with 100 cm paths separating between blocks. randomized complete block design with three blocks was used to carry out this field experiment. the recommended doses of each brewery sludge were applied on experimental plots fourteen days in advance to crop seed sowing, while np fertilizer was applied according to the recommended time and method by hurc (1996). brewery sludge can be incorporated into the soil before sowing any crop. bs is a slowrelease organic fertilizer that can provide macro and micronutrients to crops. incorporating bs before planting the maize crop can benefit the plant because the brewery sludge may provide necessary nutrients to microorganisms that fix nitrogen from the air and increase the nutrient availability in the soil. bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 27 additionally, the physicochemical properties of experimental soil were also analyzed to elucidate the change that occurred after the application of brewery sludge rates. 2.4. physicochemical data collections and experimental procedures soil samples were collected from all experimental plots and selected soil chemical parameters were analyzed in haramaya university soil chemistry and central laboratories. the ph of the soils suspension in a 1:2.5 (soil: liquid ratio) was measured potentiometrically using a glass-calomel combination electrode (van reeuwijk, 1992). the walkley and black (1934) wet digestion method was used to determine soil carbon content. total n was analyzed using the kjeldahl digestion, distillation, and titration method as described by black (1965) by oxidizing the organic matter in concentrated sulfuric acid solution (0.1n h2so4). since the ph of the soil in the study area ranges from 8.49 to 8.67, available p of soils and brewery sludge was analyzed according to the standard procedure of olsen et al. (1954). extractable heavy metals (fe, cu, zn, mn, cr, mo, co, pb, se, and cd) were extracted by diethylene triamine pentaacetic acid (dtpa) extraction method of lindsay and norvell (1978) and all these heavy metals were measured by atomic absorption spectrophotometer. extractions were performed with three replications. metals recovered at each extraction were separately analyzed and the cumulative metal recovery and cumulative volume of extractants used for the extractions were recorded. the dtpa extracting solution was prepared to contain 0.005m dtpa, o.oim cacl2, 0.1m tea (triethanolamine), adjusted to ph 7.30, and shaken for 2 hours. to prepare 10 liters of the solution, 149.2 g of reagent grade (hoch2ch2)3n (tea), 19.67 g of diethylene triaminepenta acetic acid (dtpa), and 14.7 g of cacl2-2h2o were dissolved in approximately 200 ml of distilled water. thereafter, sufficient time was allowed for the dtpa to be dissolved and diluted to approximately 9 liters. it was then adjusted to 7.30 ± 0.05 ph and 1n hc1 while stirring and diluting to 10 liters. this solution is stable for several months. another commonly designated name and formula for dtpa is [(carboxymethyl) imino] bis (ethylenenitrilo) tetraacetic acid with the formula [(hococh2)2nch2] 2nch2cooh with a formula weight of 393.35. extracting procedure ten grams of air-dried soil was placed in a 125-ml conical flask, and 20 ml of the dtpa extracting solution was added. each flask was covered with stretchable parafilm and secured upright on a horizontal shaker with a stroke of 8.0 cm with a speed of 120 cycle min-1. after 2 hr of shaking, the suspensions were filtered by gravity through whatman no. 42 filter paper. the filtrates were analyzed for fe, cu, zn, mn, cr, mo, co, pb, se, and cd using atomic absorption spectrophotometry and appropriate standards. the concentration of heavy metals (mg kg-1) in the soil (before application of treatments) and brewery sludge used for the experiment were given in table 1. physicochemical properties of soil and brewery waste were evaluated in the soil laboratory. 2.5. agronomic data collections and procedures a total of ten plants per experimental plot were randomly selected from the inner rows and were tagged, from which data on plant height (cm), ear length (cm), ear width (cm), and thousand kernels weight (g) were recorded based on their recommended procedures by hurc (1996). the grain yield (t ha-1) and total cobs weight (kg plot-1) were calculated using the relevant procedures. the grain yield (air-dried) was computed in t ha-1 based on the total population of plants (32,000) per hectare using the relevant variables. gyha=yp x pha where, gyha = grain yield per hectare, yp = average grain yield per plant, and pha = plant population per hectare. plant samples collected at harvest were partitioned into vegetative and grain form for the determination of n content in grain and straw. the straw and grain samples were ground and sieved through a 0.5mm sieve. the n content of the grain and straw samples were determined using the wet digestion method, which involved the decomposition of the plant tissues using various combinations of hno3, h2so4, and hclo4 by using kjeldahl procedure. total n uptakes in straw and grain were calculated by multiplying the n contents by the respective straw and grain yields per hectare. in the recent past, concentration is used in place of nitrogen content as it is preferred to nitrogen concentration. the nutrient concentration multiplied with dry matter 100-1 gives uptake either in grain or straw. dry bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 28 matter is expressed in tonnes or kgs ha-1. for calculating uptake, it is convenient to express a dry matter of grain or straw in kg ha-1. so the formula used to calculate the uptake of the nutrient is: n% in grain or straw*dry matter of grain or straw in kg ha-1 ÷100 = uptake in kg ha-1 in grain or straw (rao, 2015). if % n in the grain is 1% and %n in straw is 0.2%, grain yield is 5000kg ha-1 and straw yield is 6000kg ha-1 then uptake in grain and straw is: 1×5000÷100=50kg ha-1 n in grain 0.2×6000÷100=12kg ha-1 n in straw 2.6. data analysis the data were subjected to analysis of variance (anova) as applicable to rcbd in factorial arrangements for each location using the general linear model of genstat 16th edition updated version. treatment means that were significantly different were separated using the tukey test at a 5% level of significance. 3. results and discussions 3.1. physicochemical data 3.1.1. physicochemical characteristics of bs and background soil samples before application of treatments the analysis of physicochemical characteristics of experimental soil (background soil samples) and bs before application of treatments revealed that the ph values obtained from the bs and background soil were 8.67 and 8.55, respectively. this indicated that the brewery sludge used for field experiments had a 1.38% increase over the ph result obtained from background soil (table 1). the value is in the range of slightly alkaline. this result is in contrast to ajmal and khan (1984) who carried out field trials and reported that the effluent was found to be acidic, and had high biological oxygen demand (bod) and chemical oxygen demand (cod) due to the presence of large amounts of solids. moreover, these authors claimed that the effluent was rich in ammonia-nitrogen, nitrate-nitrogen, phosphorus, and potassium so that its application to the soil increased the values of available nutrients in the soil. the comparison of background soil and bs indicated that the potential nutrient content was available in sludge that was added to agricultural soil for crop production. similarly, the analysis of brewery sludge quality showed that the sludge had a high content of total nitrogen, organic carbon, total phosphorus; slightly high ph level, and high heavy metals (zn, fe, ni, co, cu, and se) (table 1). however, the levels of these heavy metals did not exceed that is considered a safe level for health as per world health organization (who) standard (table 1). however, the biological impact on soil microorganisms needs to be studied for sustainable use of the brewery sludge (alayu et al., 2018). table 1: physicochemical characteristics of experimental soil (background soil samples) and bs before the application of treatments. parameters background soil samples bs difference in percentage ph 8.55 8.67 1.38 total n, % 0.09 1.33 93.23 organic carbon, % 1.50 3.50 57.14 available p, mg kg-1 9.23 39.75 76.78 zn (mg kg-1 soil) 7.50 28.50 73.68 fe (mg kg-1 soil) 23.39 20.50 -12.36 cd (mg kg-1 soil) 1.31 1.27 -3.05 ni (mg kg-1 soil) 9.67 31.33 69.14 mn (mg kg-1 soil) 3.61 0.83 -77.01 co (mg kg-1 soil) 18.00 33.00 45.45 cu (mg kg-1 soil) 2.50 20.00 87.50 se (mg kg-1 soil) 11.94 12.56 4.94 mo (mg kg-1 soil) 1.00 0.45 -55.00 cr (mg kg-1 soil) 1.63 0.47 -71.17 bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 29 the high content of nutrients and other chemical properties like ph of brewery sludge indicate that its application to the soil can improve the organic matter and soil fertility of the production area. this indicates that mineral fertilizer can be substituted by brewery sludge for their positive effect of risk-free heavy metals level, low cost in comparison with mineral fertilizers (bulti merga et al., 2020), and keep our environment clean area. 3.1.2. heavy metal accumulation in the soil after maize crop harvest zinc (zn), cadmium (cd), nickel (ni), copper (cu), and chromium (cr) of treated sludges were laid within the allowed soil health boundaries. data in various rates of brewery sludge application were compared with the maximum permissible concentration of potentially toxic elements (pte) derived from the european union code of practice (eucp) (ec, 2001). these values have been produced to protect food quality and the environment (lester & edge, 2001). comparatively, the highest concentration for zn was observed under application of brewery sludge at 5 t ha-1 (17.5 mg kg-1) compared to the application of 15 t ha-1 (11.5 mg kg-1), 12.5 t ha-1 (17 mg kg-1), 10 t ha-1 (15 mg kg-1), 7.5 t ha-1 (5 mg kg-1) and np (14 mg kg-1) which all were below the international standard tolerant limit (table 2). the bss are dynamic in characteristics which vary widely by original waste composition and solid waste treatment courses, along with sludge treatment processes; hence, sludge may contain additional toxic substances that cause harmful effects to soil microbial activities through the transfer of antibiotics in the soil environment (chen et al., 2016) and humans through transmission in the food chain (arthurson, 2008) when they are applied for agricultural uses. therefore, the characterization of the bs quality is vital to conclude on its viability for recycling it for agricultural application to promote waste resource utilization besides environmental protection. table 2: heavy metal accumulation in the soil after maize crop harvest. treatments mean concentration of heavy metals in mg kg-1 soil zn fe cd ni mn co cu se mo cr soil boundary values (eu) 100 3 50 20 80 2.0 150 sludge boundary values (eu) 2500 30 300 1000 1000 background soil 7.5 23.39 1.31 9.67 3.61 18 2.5 11.94 1 1.63 2.5* 7.00 25.79 1.14 28.33 3.99 25.00 7.00 13.06 0.91 1.63 change (%) -6.67 9.31 -12.98 65.87 9.52 28 64.29 8.58 -9.00 0.00 5* 17.50 25.58 1.25 8.67 3.77 8.00 3.50 12.19 0.73 1.44 change (%) 57.14 8.56 -4.58 -10.34 4.24 -55.56 28.57 2.05 -27 -11.66 7.5* 5.00 25.66 1.28 15.00 4.22 30.00 5.50 13.12 0.27 1.25 change (%) -33.33 8.85 -2.29 35.53 14.45 40.00 54.55 8.99 -73.00 23.31 10* 15.00 25.55 1.02 30.33 3.93 36.00 6.00 12.31 0.73 1.34 change (%) 50.00 8.45 -22.14 68.12 8.14 50 58.33 3.01 -27.00 -17.79 12.5* 17.00 25.29 1.08 28.67 3.09 34.00 4.50 12.25 0.45 0.72 change (%) 55.88 7.51 -17.56 66.27 -14.40 47.06 44.44 2.53 -55.00 -55.83 15* 11.50 25.89 1.18 17.00 4.28 32.00 9.00 13.25 1.36 1.13 change (%) 34.78 9.66 -9.92 43.12 15.65 43.75 72.22 9.89 26.47 -30.67 np-fertilizer* 14.00 25.39 1.25 22.33 3.93 32.00 4.50 13.37 1.82 0.34 change (%) 46.43 7.88 -4.58 56.70 8.14 43.75 44.44 10.70 45.05 -79.14 0** 13.50 25.84 0.83 18.33 3.69 11.00 4.00 12.69 1.55 0.66 change (%) 44.44 9.48 -36.64 47.24 2.17 -38.89 37.5 5.91 35.48 -59.51 eu = european union standard, 2001; * = after application of brewery sludge; ** = without application of brewery sludge, and change (%) = the change in percentage for heavy metal accumulation in the soil before and after application of bs. bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 30 similarly, the soil that was treated with brewery sludge at the rate of 10 t ha-1 was found to contain the highest accumulation cobalt (co) concentration of (36 mg kg-1). furthermore, the application of brewery sludge at the rate of 12.5 t ha-1 accumulated cobalt (co) concentration of 34 mg kg-1 in crop soil that exceeded the maximum tolerable values. the accumulated cobalt in the soil after the crop harvest was due to the application of various rates of brewery sludge that were higher than the permitted soil boundary values adopted from european union standard (eu), except for the plots that received 0 t ha-1 and 5 t ha-1 t. this is because of the dynamic characteristics of the brewery sludge (chen et al., 2016). in comparison with the amount of cobalt that was available before brewery sludge application, the use of brewery sludge increased the level of heavy metal in soil by the range of 28 to 50% after maize crop harvest. this revealed the proportional increase of cobalt, heavy metal, accumulation in the grain of maize. although varied, the concentrations of all other elements especially zn (5-17.5 mg kg-1); ni (8.67-30.33 mg kg-1), and cu (3.5-9 mg kg-1) were below the maximum tolerable limits of 100, 50, and 80 mg kg-1, respectively (table 2). in this study, it was observed that the concentrations of co and se and all the heavy metal ions investigated exceeded the background tolerable limits; yet the concentrations of each element varied with each treatment. the result obtained from the plots that were treated with zero brewery sludge rate (control treatment) was also higher than the maximum tolerable value in context to selenium (se). this indicated that the concentration of this element was already high in the soil of the study area. moreover, there was no proportional increase of heavy metals with the increasing levels of bs rates. 3.2. yield and yield components of maize 3.2.1. growth performance plant height was measured at 50% physiological maturity. the analysis of variance revealed a statistically significant (p<0.05) difference in plant height due to levels of sludge applications. increasing brewery sludge application (bs) from 0 to 15 t ha-1 increased plant height consistently. the maize plant height significantly increased with the application of bwss as compared to np mineral fertilizer. the calculated differences between bs treatment with the control treatment and recommended np fertilizer rate ranged from 66 to 89% and 13 to 28%, respectively (table 3). the increase of plant height could be due to the increased plant cell elongation and division that occurred from the availability of essential nutrients by the applied bs. plants must obtain the following mineral nutrients from their growing medium:the macronutrients: nitrogen (n), phosphorus (p), potassium (k), calcium (ca), sulfur (s), magnesium (mg), carbon (c), oxygen (o), hydrogen (h); the micronutrients (or trace minerals): iron (fe), boron (b), chlorine (cl), manganese (mn), zinc (zn), copper (cu), molybdenum (mo), nickel (ni) (allen et al., 2007). the essential nutrients investigated in this research is not only nitrogen (n) and phosphorus (p) because the following nutrients also included: the essential micronutrients (or trace minerals): iron (fe), manganese (mn), zinc (zn), copper (cu), molybdenum (mo), and nickel (ni). similarly, szymanska et al. (2016) reported that there was a trend of an increase in the height of maize plants, with the application of sewage sludge when compared to control treatment. outhman and firdous (2016) also reported the significant effect of sewage sludge on plant height of wheat and barley crop at 40, 80, and 120 days after sowing. the results of maize growth attributes, ear length and ear width (table 3), revealed that the highest corn ear length (14.63 cm) was obtained in experimental plots that received sludge at a rate of 10 t ha-1 while the highest corn ear width (13.57 cm) recorded in the plots treated with lowest bs rate (2.5 t ha-1). in the corn ear width parameter, the statistical analysis revealed that the experimental plots to which bs was applied at the rate of 2.5 t ha-1 were 8.11 and 15.62% higher than the np fertilizer and control treatments, respectively. however, the highest corn ear height was recorded in the treatment that received 10 t ha-1 bs that exceeded np fertilizer and control treatments by 13.53 and 27.00%, respectively. the higher yield attributes were recorded in the treatments that received sludge than both recommended np mineral fertilizer and control treatment. the statistical analysis of corn ear length and ear width of maize plants revealed a non-significant difference in all levels of brewery sludge. but all levels bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 31 table 3: the effect of different rates of brewery sludge application on growth attributes and grain yields of maize. treatments plant height (cm) total cobs weight (kg plot-1) ear width (cm) ear length (cm) thousand kernels weight (g) grain yield (t ha-1) 2.5 137.8c 0.98c 13.57a 13.63ab 30.18ab 3.16c 5 145.22bc 1.28bc 12.77ab 14.28ab 31.25ab 4.13bc 7.5 147.80b 1.315b 12.92ab 13.58ab 30.28ab 4.31bc 10 151.97ab 1.555ab 13.32ab 14.63a 32.18a 4.35b 12.5 150.72ab 1.492ab 13.25ab 13.73ab 31.10ab 4.37b 15 156.92a 1.610a 13.05ab 14.53ab 31.43ab 5.19a np fertilizer 121.72d 0.610d 12.47b 12.65b 26.80b 2.04d 0 82.90e 0.280e 11.45c 10.68c 22.58c 0.77e lsd (0.05) 10.08 0.222 0.81 1.50 3.51 0.82 cv (%) 5.01 13.25 4.33 7.60 8.10 15.71 of bs showed a significant difference when compared with np fertilizer and control treatments on corn ear length and ear width of maize food crop. the statistical analysis revealed the improvement of maize plant growth attributes with sludge applications to crop soil. the result of the analysis indicated a highly significant (p<0.01) difference in total cobs weight per plot. the mean separation showed that the highest cobs weight (1.61 kg plot-1) was obtained from the highest brewery sludge (15 t ha-1) rate (table 3). similarly, the application of 10 t ha-1 brewery sludge rate to crop soil revealed 1.55 kg plot-1 maize cobs weight, and plots treated with zero bs rate (control treatment) was produced the lowest yield attribute value (0.28 kg plot-1). 3.2.2. grain yield and thousand kernels weight the effects of brewery sludge (bs) under the rainfed condition on grain yield and thousand kernels weight of maize was measured and revealed statistically significant difference when compared with np mineral fertilizers recommended for crop production. results of the experiment showed that the average maize grain yield for the application of different levels of sludge from 2.5 to 15 t ha-1 increased maize grain yield by 309% to 572% and 55% to 154% over the np fertilizer and control treatments, respectively (table 3). the statistical analysis of the results revealed the superiority of brewery sludge on maize grain yield at all rates (table 3). the highest grain yield (5.19 t ha-1) was obtained from plots that received a 15 t ha-1 brewery sludge rate. the least maize grain yield (0.77 t ha-1) was recorded from plots that received zero brewery sludge rate (control treatment). the results for the sludge application indicated the existence of an opportunity for increasing maize grain yield through the application of brewery sludge beyond 15 t ha-1. similarly, the result obtained from brewery sludge analysis indicated that the application of 0.96 t ha-1 bs exceeds the plots that received nps fertilizer and control treatment by 12.59% and 26.8% of maize grain yield, respectively at the northern part of ethiopia (alayu and leta, 2020). this is because of the richness of sludge with organic matter, total nitrogen and total phosphorus content, optimal ph, and salinity level including other secondary nutrients (ca2+, mg2+, na+, and k+) than that of nps and control treatments. the higher availability of essential nutrient elements from the applied sludge at the proper application might have contributed to this difference. the low yield in np fertilized and control plots might have been due to reduced leaf area development resulting in lesser radiation interception and, consequently, low efficiency in the conversion of solar radiation. application of sludge from 2.5 to 15 t ha-1 levels showed 1000 kernels weight increment from 12.6% to 20% and 33.6 to 42.5% over the recommended rate of np mineral fertilizer and control treatment, respectively (table 3). the mean separation for the treatments revealed that no significant thousand-kernel weight difference was observed between 2.5 to 15 t ha-1 sludge applications. this indicated that the application of sludge beyond 2.5 t ha-1 did not significantly increase the thousand-kernel weight of maize. the highest significant value of thousand kernels weight (32.18 g) was noted from crop soil that received bs 10 t ha-1 rate while the least result (22.58 g) was recorded in zero bs rate (control treatment). bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 32 3.2.3. nitrogen concentration in grain and straw of maize the concentration of n in corn grain was significantly (p ≤ 0.05) influenced by brewery sludge rates, while the concentration of n in the straw of maize revealed non-significant (p ≥ 0.05) influences. the highest (1.44%) n concentration in corn grain was recorded from the application of brewery sludge at 12.5 t ha-1 rate, followed by 10 and 7.5 t ha-1 which revealed similar results with the application of brewery sludge at 15 t ha-1 rate. this was significantly higher than the application of brewery sludge at 2.5 t ha-1 rate, recommended rate of np mineral fertilizer, and control treatments. further, the result of this study depicted nonsignificant differences among other brewery sludge rates (5; 7.5; 10; 12.5 and 15 t ha-1) (table 4). table 4: nitrogen concentration percentage (%) in grain and straw of maize. treatments mean concentration of nitrogen in % grain mean concentration of nitrogen in % straw 2.5 1.21 0.56 5 1.32 0.60 7.5 1.33 1.38 10 1.40 0.54 12.5 1.44 0.63 15 1.33 0.56 np-fertilizer 1.29 0.56 control 1.15 0.58 lsd (0.05) 0.18 0.91 cv (%) 7.71 77 lsd (5%) = least significant difference at p = 0.05, cv (%) = coefficient of variation, bs= brewery sludge, and np= recommended nitrogen and phosphorus rate. 3.2.4. total n uptake by maize grain and straw analysis of variance showed significant differences (p < 0.05) among brewery sludge treatments for grain n uptake, straw n uptake, and total n uptake of maize. increasing brewery sludge rates up to 15 t ha-1 also raised corn grain n uptake (68.82 kg ha-1) and the lowest n uptake (8.86 kg ha-1) value was recorded from the control treatment (table 5). application of 12.5 and 15 t ha-1 brewery sludge resulted in 609 and 676% more grain n uptake than the control treatment, respectively. the applications of np mineral fertilizer to crop soil revealed significantly the least corn grain n uptake than all other brewery sludge rates used in this study (table 5). the nutrient content of brewery sludge is better than np mineral fertilizer. hence, the sludge can substitute other mineral fertilizers and used for soil fertility improvement and higher grain yield production. similarly, maize straw n uptake exhibited an increasing trend with increased brewery sludge rate up to 12.5 t ha1, a further increase in brewery sludge rates revealed a decreasing trend. mean straw n uptake from the control treatment to the highest brewery sludge rate (15 t ha-1) ranged between 46.67 to 116.67 kg ha-1 (table 5). the applications of np mineral fertilizer recommended rate to cropped soil had significant effects on maize straw n uptake. the highest (179.45 kg ha-1) and the lowest (55.53 kg ha-1) total n uptake values were obtained from the application of 12.5 t ha-1 brewery sludge rate and the control treatments, respectively. there was a trend of linear increment of total n uptake as brewery sludge rate increased from the control treatment to the 12.5 t ha-1 rate. the highest brewery sludge rate (15 t ha-1) resulted in 223% more total n uptake than the control treatment. about 179.45 kg ha-1 total nitrogen uptake was obtained in the application of 12.5 t ha-1 bs rate; from the use of the recommended np mineral fertilizer rate, this was fallen to 72.91 kg ha-1. from the evidence of economic analysis report under the same project with this study, partial budget and marginal rate of return analysis for maize production revealed the highest marginal rate of return (44.68%) from the application of 2.5 t ha −1 bs rate. however, the mrr (21. 52%) from the application of 15 t ha −1 bs that was lower than the minimum mrr recommendation (100%) (cimmyt, 1988). the application of 5 t ha −1 bs that revealed the net benefit of 609.64 usd and marginal rate of return of 15.89 usd can be used by smallholder farmers that produce maize (bulti merga et al., 2020). bulti merga et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 33 table 5: nitrogen uptake (kg ha-1) of maize grain and straw. treatments mean nitrogen uptake by grain (kg ha-1) mean nitrogen uptake by straw (kg ha-1) total n uptake (kg ha-1) 2.5 38.33 46.67 85.00 5 54.41 46.67 101.08 7.5 57.49 46.67 104.16 10 60.95 48.22 109.17 12.5 62.78 116.67 179.45 15 68.82 52.89 121.71 np fertilizer 26.24 46.67 72.91 control 8.86 46.67 55.53 lsd (0.05) 19.54 75.10 80.24 cv (5 %) 6.74 22.00 13.02 lsd (5%) = least significant difference at p = 0.05, cv (%) = coefficient of variation, bs= brewery sludge, and np= recommended nitrogen and phosphorus rate. 4. conclusion managing industrial waste is one of the ways to protect our environment from harmful pollutants. as such, manufacturers and companies might be held responsible for the waste they generate. the result of the comparison of the different rates of brewery sludge to recommended np fertilizer and control (zero application) was found to be promising in reducing environmental pollution because of the negative effects of brewery sludge disposal. the result indicated that between 2.5 to 15 t ha-1 brewery sludge rates, maize grain yield increased by 309 to 572% when it was compared with np mineral fertilizer treatment but this result was fallen to 55 to 154% with control treatment. there was a proportional increase in brewery sludge rate and corn grain yield from least to the highest value. furthermore, the study revealed that the highest concentration of cobalt (36 mg kg-1) was recorded from the soil that received 10 t ha-1 brewery sludge treatment. however, this result was statistically non-significant with other treatments that were above tolerable values. the application of 12.5 t ha-1 brewery sludge rate to crop soil revealed the highest total n uptake value (179.45 kg ha-1), but this value was fallen to the least (55.53 kg ha1) in soils treated with zero brewery sludge. the physicochemical analysis of brewery sludge that was collected from the brewing industry showed 3.5% organic carbon, 1.33% total n, and 39.75 mg kg-1 available phosphorus. these components supplemented crop soils to increase their ability in the sustainable release of essential nutrients for maize plants. maize grain yield was high with the soil crop that was treated with brewery sludge. this indicated that brewery sludge has the potential of releasing nutrients slowly when applied to agricultural soil that can increase the ability of soil for the sustainable provision of nutrients to plants. the slow release of nutrients prevents leaching of excess plant-available nutrients and possible contamination of ground and surface water. acknowledgments the authors honestly acknowledge the harar beer industry for financing and haramaya university for laboratory evaluation of the waste sludge and background soil samples. reference aguilera, e., lassaletta, l., sanz-cobena, a., garnier, j., & vallejo, a. 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(2016). response of maize (zea mays l.) grown for grain after the application of sewage sludge/reakcja kukurydzy uprawianej na ziarno po zastosowaniu osadow sciekowych. journal of central european agriculture, 17(1): 139-154. van reewijk, l. p. (1992). procedures for soil analysis. (3rd ed.), wageningen, the netherlands: international soil reference center (isric. walkley, a., & black, i. a. (1934). method for determining soil organic matter and a proposed modification of the chromic acid titration method. soil science, 37: 29–38. doi: 10.1097/00010694-193401000-00003. 63 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper households’ willingness to pay for livestock insurance in karrayyu pastoralist community: an attempt for risk reduction jeleta gezahegne kebede1, birku reta entele1, alemayehu ethiopia derege2,  1department of economics, school of humanities and social science, adama science and technology university, p.o.box 1888, adama, ethiopia 2department of economics, school of business and economics, arsi university, p.o.box 192, assela, ethiopia article info abstract keywords: livestock insurance willingness to pay karrayyu community ethiopia the study aim to investigate pastoralist community’s willingness to pay (wtp) and factors that determine their willingness to pay for index based livestock insurance scheme. using survey data collected by systematic sampling method, the study adopted an interval data logit model and estimated households’ wtp for index based livestock insurance for camels, cattle and goats & sheep’s separately. the study finding reveals that there is huge demand for livestock insurance scheme following recurrent drought and increased chance of losing their livestock. the estimated result shows that total wtp for camel, cattle and goat and sheep is about 2.7, 4.27, and 4.4 million birr per year respectively. age of household head, family size, number of camel size and value of household asset have significant positive effect; where as non-farm income and distance from local market have negative effect on households’ probability of joining camel insurance. the cattle model shows that value of household assets have negative effect and size of the cattle has positive effect on the probability of households’ willingness to join cattle insurance and their wtp. the goat and sheep model shows that number of goat and sheep has positive effect; income from livestock and age of household head has negative effect on households’ probability of joining livestock insurance and wtp. in all models, the starting bid price has negative significant effect on the demand for livestock insurance, confirming the law of demand. policy suggestion is that public or private insurance company can intervene through supply of livestock insurance for commercial purposes as well as to mitigate the side effect of covariate shocks leading to smooth consumption and stable income stream of households. preferential policy intervention for camel insurance may yield better outcome as the community gives more value to the camel. 1. introduction in developing countries, poor households are often faced with unpredictable income streams and unpredictable expenditure needs. literatures investigate strategies that these households employ so as to cope up with the shocks to smooth consumption. the consequences of these shocks may be both short term and long term on the welfare of households depending on how households  corresponding author, e-mail: aethiopia7@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.114 cope with such shocks. especially, if covariate shocks like drought are hard felt and affect households’ welfare for long time after the shock, households may opt for less risky technologies so as to avoid permanent damage leading to lower returns on average (ali et al., 2014). the understanding of the shocks, household vulnerabilities, risk management strategies, and coping http://www.ejssd.astu.edu/ mailto:aethiopia7@gmail.com https://doi.org/10.20372/ejssdastu:v7.i1.2020.114 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 64 strategies to mitigate the effect of these shocks is very crucial in order to prioritize and design appropriate policy. understanding the effect of shocks like drought and health on household consumption, income, labor supply and input application is area of concern recently. specifically, the effect of past shocks on current consumption and input application in rural areas is very crucial to design appropriate policies for the coping strategies since the effect of these shocks has its role in explaining perpetuating poverty (fletschner et al., 2010).the livelihood and wellbeing of rain fed households in developing countries are greatly influenced by the climate change. such supply side shocks have big impact on prices, influencing production and consumption patterns. households in poor rural areas of developing countries respond using different mitigating strategies to such production shock and livestock death that are related to weather changes like rainfall failure. asset accumulation, diversification of income sources, risk sharing network participation, and adoption of less risky activities are some of risk management strategies. sales of asset, reducing nonessential expenditures, migrating from drought affected areas, drawing on social networks, and relying on formal and informal borrowing are used as coping strategies to such covariate shocks (caeyers and dercon, 2008). the findings of literatures shows households cope with different shocks at the expense of long-term cost in the absence of credits or formal insurance. accordingly, households in different socio economic settings cope to both idiosyncratic and covariate shocks using different coping strategies like reducing investment in education, increasing child labor, reducing farm and livestock investment and reallocating resources across sector indicating that these shocks may contribute for explaining persistent poverty in poor countries in general and that of rural households in particular (wheeler, 2011). ethiopia experiences recurrent weather and drought related shock, absence of formal insurance for rural households and very limited access to finance for the poor rural households (pan, 2009). index insurance has gained widespread interest in recent years as an instrument for reducing uninsured risk in poor rural areas that typically lack access to commercial insurance products. these financial instruments make indemnity payments based on realizations of an underlying index – based on some objectively measured random variable – relative to a pre-specified threshold (barnett et al. 2008). index insurance offers significant potential advantages over traditional insurance. because indemnity payments are not based on individual claims, insurance companies and insured clients need only monitor the index to know when payments are due. this sharply reduces the transaction costs of monitoring and verifying losses, while also eliminating the asymmetric information problems (i.e., adverse selection and moral hazard) that bedevil conventional insurance. these advantages have sparked considerable interest in index insurance for poor regions otherwise lacking formal insurance access (barnett and mahul, 2007). hence, such kinds of insurance can also be applicable to pastoralist community whose livelihood mainly depends on livestock rearing in areas like fantale and boset woredas of karrayyu community. livestock insurance for pastoral community like karrayyu is unquestionably important as the people lead their livelihood from animal husbandry. the predominant agricultural practice in this woreda is pastoralism. camels, goats and cattle are the most common livestock (csa 2005) and many of these livestock die because of drought/ disease yearly. the karrayyu are attempting to cope with the changing circumstances as a result of land dispossession and climate change by combining farming with livestock management, petty trading and wage employment. however, these responses at the moment are not adequate to cope with the pressures, as changes are taking place too quickly to allow for adequate adaptation. therefore, we found that risk management practices through livestock insurance, are perhaps, one innovative policy to overcome food insecurity and loss of livestock. given climate change a serious issue, it is vital, therefore, to find a means through which we can optimize our return from livestock population. livestock insurance can be taken a good example to avoid the risky investments for livestock owners. when it comes to the case of fantale and boset, our case study, to the best of our reference, there is no study under taken concerning the subject matter so far. therefore, this jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 65 study will fill the gap between insurance demand (pastoralist community) and insurance providers through answering question like whether potential demand for livestock insurance is available and then recommend for potential insurance provider companies for intervention and thereby open a way for livestock insurance commercialization (for insurance companies). 2. data and methodology 2.1. study area the study is designed for the pastoralist community of fantale and boset woreda i.e karrayyu community in the eastern shewa zone of oromia regional state. the two woredas are mainly known by pastoralist livelihood; and the major livestock produced are camel, cattle, goat and sheep. both woredas are located in the great rift valley. the administrative center of fentale woreda is metehara town and that of boset is wolenciti town. both metehara and wolenciti are located east of addis ababa on the main high way that connects ethiopia and djibouti at the distance of 193 km and 135 km, respectively. kareyu community commonly resides in central rift valley of eastern showa zones of oromia regional state. the figure below portrays residential woredas of karayu community and the two darken encircled areas; boset and fentale woredas are chosen for this study. boset woreda is adjacent to adama and fantale is also adjacent to boset woreda to the eastern part of the country respectively. 2.2. sample size and sampling methods the study is based on household survey using structured survey instruments (questionnaires) to collect data and information at woreda, kebele and household levels. the selected kebele from each woreda and selected household respondent from each kebele are summarized in table 1. figure 1: map of study area (boset and fantale woreda) table 1: summary of sample size woreda total kebele selected kebele sample respondent planned respondent actual data fantale 18 3 60 180 165 boset 20 2 60 120 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 66 * ' ........1 i i i wtp x    mixed sampling of, purposive and systematic sampling methods are used to select sample respondents for the study. given the administrative structure of ethiopia, sample zone and woredas are selected on purposive basis. this paper was primarily targeted pastoralist community of east showa zone where karayyu communities are living. although karayyu communities are living sparsely in different woredas of north east shoa, boset and fantale woredas were among the selected areas on purposive as large proportion of pastorals are living in arid rift valley of those areas. the kebeles were selected purposively based on the number of livestock dwellers are holding and based on the kebeles vulnerability to livestock shock due to different reasons. however, from each kebeles the household head respondents were systematically drawn from the total kebele population. given kebele is the smallest official administrative structure in ethiopian geopolitics, a representative sample size should have to make at least 10% of its total population and accordingly, this paper estimated to draw 60 individual household heads from each kebele’s of selected woredas. the target individual household heads were drawn from each kebeles using systematic sampling technique. the systematic lottery method was implemented to the list document (kebele level sampling frame) in cooperation with kebele administrator. hence about 165 households were selected and used for analysis. 2.3. model and analytical framework arrow et al. (1993) studied the applications of contingent valuation (cv) and provides insightful recommendations to maximize the reliability of cv estimates, among those relevant to our study are: (1) use of representative sample, (2) phasing cv questions in the form of hypothetical referenda in which respondents are told how much they would have to pay for each product or scenario choice before asking them to cast a simple yes or no answer, (3) reminding respondents of their actual budget constraint when considering their willingness to pay, (4) providing some sort of a “would not choose” option in addition to the “yes” and “no” option on the referendum, and (5) breaking down willingness to pay by a variety of respondent’s characteristics. a small literature applies cv methods to study willingness to pay (wtp) for agricultural insurance. patrick (1988) and vandeveer and loehman (1994) used a single dichotomous (yes/no) choice question to study producers’ demand for a multiple peril crop insurance, rainfall insurance and other modifications of crop insurance. mccarthy (2003) and sarris et al. (2006) used similar single cv question to study pattern of demand for rainfall insurance in morocco and tanzania, respectively. our approach deviates from others in three interesting ways. first, we model household’s demand for index based livestock insurance (ibli) as a sequential decision. households will be first asked pastoralists to choose a proportion of their herd (among 0%, 25%, 50%, 75% and 100%) that they wish to insure. and so conditional on their chosen proportion, they will be then asked a series of dichotomous wtp questions. this is contrastable with the standard joint decision approach widely used in the literature, in which respondent are asked to consider insurance contracts with pre-specified combinations of coverage and price (e.g., full coverage contract in which pastoralists are required to insure all their herd). as in reality, we cannot observe households’ total herd sizes prior to their insurance decision – but rather the herd sizes households are willing to insure – and various literatures related to agricultural insurance provide evidence that the insured acreages vary across producers and far from full coverage (barnett et al. 2004, miranda and venedov 2001, among others), the standard, pre-specified coverage insurance question may not well replicate the actual insurance decision. second, we have used double-bounded cv method, in which pastoralists were asked a sequence of dichotomous insurance questions that progressively narrows down the range of their unobserved wtp. specifically, pastoralists were first asked to consider a specific insurance and if they are willing to pay at a specific price. a follow-up question with higher (lower) price are then asked if they response “yes” (“no”) to the first question, and the process continues until we can classify their willingness to pay into different intervals classified using prices. this is based on the assumption that the individuals compare their utility from the proposed livestock insurance scheme with the current situation and decide whether to accept or reject the offered bid levels. this implies that the probability that households to buy the proposed livestock insurance policy can be expressed as the difference of their utility functions with and without jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 67 ' 11 1 ' ' 10 ' ' 01 ' 00 ln 1 ( ) ln ( ) ( ) ln ...2 ln ( ) ( ) ln ( hn i i i i h i i i i i l i i i i i l i i i p x d p x p x d l p x p x d p x d                                                                * ' ........1 i i i wtp x    the proposed livestock insurance. then, assume that the true willingness to pay of household i for the livestock insurance product is given by equation 1. where, x is a vector of explanatory variables, β is a vector of coefficients to be estimated, ε is a random error term assumed to be randomly and independently distributed with mean zero and constant variance, σ2. in dichotomous choice specification, the wtp* value is not directly observed. however, we observe a range of wtp values from the survey response. as we have shown above, we use double bounded dichotomous choice elicitation method1. under this method, each respondent is given two bids, the first bid (pf) and the second higher (ph) or the second lower (pl) bids, depending whether the individual responds ‘yes’ or ‘no’ to the first bid. this means that we have the following four possible outcomes for each respondent. , if respondent i says ‘yes’ and ‘yes’ to the 1st and 2nd higher bids, respectively = 1, if respondent i says ‘yes’ and ‘no’ to the 1st and 2nd higher bids, respectively = 1, if respondent i says ‘no’ and ‘yes’ to the 1st and 2nd lower bids, respectively and = 1, if respondent i says ‘no’ and ‘no’ to the 1st and 2nd lower bids, respectively. then, the mean wtp is estimated by maximizing the following log likelihood function (cameron and quiggin, 1994; haab, 1998)2. where, φ(.) is the standard normal cumulative distribution function and β and λ are parameters to be estimated. 1 we use double-bounded elicitation method instead of triple or quadruple methods because the additional efficiency gain from adding third or fourth follow up question is relatively small and it can increase the chance of inducing response effects (hanemann and kanninen, 1999; cooper and hanemann, 1995; yoo and yang, 2001). if the response of individuals to the second bid is independent of their response to the first bid, each response can be estimated independently. however, various studies have shown that the second response is more likely to be dependent on the first response (cameron and quiggin, 1994; an and ayala, 1996; asfaw and von braun, 2005). therefore, in a double bounded dichotomous choice approach, the bivariate normal probability density function is the appropriate specification to estimate consistent mean values3. the mean wtp can then be computed based on the method suggested by hanneman and kanninen (1999) and kriström (1990). so at the beginning of each year t when state of the world is unknown, household i first chooses the optimal livestock investment and insurance to maximize the standard intertemporal discounted utility. the state of the world is realized at the end of the year and so ibli makes indemnity payment to compensate for livestock loss, which then adds to the livestock accumulation dynamics in. in this setting where household is considering a hypothetical ibli, we consider a sequential insurance decision, in which household first chooses the optimal proportion of herd to insure, without prior knowledge of the actual ibli premium. conditional on their optimal insurance decision and beliefs – which also govern their expectation of the ibli premium – the household’s equilibrium conditions to imply an optimal insurance decision. evaluating the insurance decision at the selfinsurance equilibrium (without ibli), an equilibrium premium rate, which makes household indifferent between purchasing or not purchasing ibli and so representing household’s maximum willingness to pay for ibli conditional on their chosen insuring proportion, will also be considered. preferences, subjective beliefs, wealth and other household-specific characteristics thus serve as the key determinants of household’s insurance decision in our setting. and theoretical predictions can be made regarding insurance demand determinants according to a standard neoclassical model. 2 this model can be estimated using standard econometrics packaged bivariate probit algorithms such as those offered in the limdep software. 3 in special cases where the correlation coefficient between the error terms of the first and the second response equations is zero, the two responses are independent and if the correlation is 1, the two responses are essentially the same. in both cases the bivariate probit specification is not appropriate. 11 1 i d  10 i d 01 i d 00 i d jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 68 first, with respect to household’s preference, wtp will be increasing in risk aversion and decreasing in household’s discount rate in a setting without asymmetric information (e.g., households fully understand the insurance contract). second, with respect to their subjective expectation and beliefs, wtp will be increasing in household’s perceived livestock mortality risk and in household’s expected insurance payout taking into account the perceived basis risk associated with ibli product (e.g., the correlations between individual mortality losses and the predicted mortality index that governs ibli indemnity payout). third, by the standard wealth effect, household’s income and assets represent the extent of financial resource to afford ibli, which have positive impact on insurance decision. as the welfare impact of a formal risk management instrument like ibli depends largely on the effectiveness of the existing risk-coping mechanisms (morduch, 1995), household’s wealth could also reflect availability of existing self-insurance capacity and so could have negative impact on insurance decision. theoretically, wealth thus could have ambiguous impact on insurance decision. by similar token, degree of credit constraint also plays key but ambiguous role in household’s wtp for insurance. on one hand, credit constrained households may value reduction in asset risk provided by ibli more highly because they have lesser ability to smooth consumption ex post by other means. on the other hand, the shadow value of their needy liquid asset may be too high to make ibli attractive. table 2: the descriptions of variables used in the model s. no. list of variables used in the model description of the variable expected sign w.r.t. dependent variable 1 age age of household head in years positive 2 education years of schooling completed by household head positive 3 dead camel the number of camels lost by death from household in a year positive 4 crop income total revenue generated from crop sale in a year positive 5 non-farm income total income generated from non-farming activities in a year positive 6 family size the number of families living together with the household head since the last six months negative 7 value of asset the estimated total market value of household assets positive 8 total land holding the total land size of household head in hectare positive 9 distance from market the distance between home and market place in kilometer (time) negative 10 number of trainings the number of times that the household head took trainings on farming in a year positive 11 livestock income the total income of households from the sale of livestock and its products in a year positive 12 starting bid the minimum starting bid price of camel, cattle and goats & sheep that the household head is willing to pay for insurance negative 13 the insurance coverage the proportion of livestock (camel, cattle and goats and sheep) that the insured household head is willing to purchase for it negative 14 occupation the type of occupation of household head (dummy variables; 1 if pastoral, 0 if mixed) positive 15 shock severity severity index (calculated based on rank level) level for different shocks that the pastoral community faces positive 16 mitigation practice the type of mitigation strategy followed by household head (in most preferred orders) negative 17 adaptation strategies the types of adaptation strategies followed during shock period in most preferred orders negative 18 access to information the accessibility of information to household level through different alternatives (and in its preferential sequences) positive 19 gender dummy variable for the gender of household head (1 for male and 0 for female) jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 69 many of these predictions have been empirically verified especially in the insurance markets in developed countries. however, factors that deviate the economic setting away from full information – e.g., household’s awareness, ability to understand the product and trust that condition their perceived cost and benefit of ibli – are shown theoretically and empirically to influence demand for insurance and other financial instruments (cole et al., 2009). these factors are expected to serve as important demand determinants for a new product like ibli among the targeted pastoralist clients in karrayyu with very limited knowledge of insurance. 2.4. list of variables used in the model the study has formulated three different analytical frame works (econometrics models) such as camel model, cattle model and goats & sheep model for estimating respective household willingness to pay for the respective livestock type (table 2). the models are separately analyzed in order to accurately estimate household willingness to pay for livestock insurance. the only thing that makes the three models similar is the personal information (household characteristics) that, which do not vary across livestock model (cattle, camel and goats and sheeps) such as age, education, gender, occupation and the like. the hypothetical relationships between the dependent variable and the interest variable are constructed based on the review of literature. the hypothesized relationship could be subjected to change for the study area, right after hypothesis testing and analytical regression model result. 3. result and discussion 3.1. descriptive analysis because of the fact that respondents’ livelihood depends on livestock and livestock products income, for instance the average income obtained from camel is 3077 birr, from goat and sheep is 2914 and from cattle is 9478 birr per year. some households have also off farm income generating activities and hence on average about 1650 birr non-farm income earned per year. the average education level attained in the study area is 1.22 years schooling ranging from 0 schooling to 9th grade complete. in general the respondent’s descriptive statistics is summarized and categorized in to camels, cattle and goats and sheep (table 3). of the total 165 sampled household, about 47 respondents have camels. the maximum average willingness to pay for the proposed insurance for camels is about 107.23 birr per year and the minimum average willingness to pay is 67.34 birr per year. the average population of camels per head is about 13.85 and the mean age of sampled households for this model is 36.85 years. in fantale woreda, crop cultivation, though rare, table 3: statistical summary for camels’ model variable obs mean std.de. min max starting bidl 47 50 0 50 50 mawtph_yes 47 107.23 18.53 50 135 miwtph_no 47 67.34 29.79 20 100 number of camel 47 13.64 9.58 2 45 age 47 36.85 5.49 26 49 education 47 .28 1.17 0 9 number of dead camel 47 .34 .59 0 3 crop income 47 22697.39 27304.26 0 108150 non_farm_i~e 47 1067.66 3938.15 0 21600 family size 47 5.77 1.84 3 14 value of hh asset 47 21249.64 16423.86 2245 70850 total land hold 47 5.44 5.87 0 21 distance market 47 21.29 7.17 10 30 number training 47 3.74 1.37 1 6 livestock income 47 27464.47 24589.1 1000 99755 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 70 is also practiced using irrigation and the estimated average income from crop cultivation, from non-farm income and from aggregate livestock income are 22697.39, 1067.66 and 27464.47 birr per year, respectively. in addition to this, the average total land hold, average distance of their home from local market, average of their value of household asset are 5.44 km, 21.29km, and 21249.64 birr respectively. finally the average family sizes of sampled household are 5.76. the same explanation holds for cattle, and goat and sheep (table 4 and 5). of the total 165 sampled households, only 137 of them have cattle in fantale woreda. the maximum average willingness to pay for the proposed insurance for cattle is about 56.8 birr per year and the minimum average willingness to pay is 27.40 birr per year. the average population of cattle per head is about 12.2 and the mean age of sampled households for this study is 40 years. table 4: statistical summary for cattle table 5: s statistical summary of goat and sheep from the survey variable obs mean std.de. min max starting bid ~l 137 30 0 30 30 miwtpcattle1 137 27.41 12.17 5 60 mawtpcattle1 137 56.79 29.77 15 100 number of cattle l 137 12.16 8.25 2 45 age 137 40.04 8.55 25 69 education 137 1.11 2.16 0 9 number of dead cattle 137 .8 .99 0 5 crop income 137 23559.72 23555.47 0 120000 non_farm_i~e 137 1591.89 4015.57 0 21600 family size 137 5.61 1.76 1 14 value of hh asset 137 36483.88 120653.5 0 132510 total land hold 137 3.83 9.33 0 100 distance from market 137 19.42 7.55 7 30 number training 137 3.21 1.42 0 6 livestock income 137 16210.47 19132.61 0 99755 variable obs mean std. dev. min max starting bid~t 139 10 0 10 10 miwtpgoat 139 12.42 6.60 0 20 mawtpgoat 139 21.80 10.67 5 50 number of goat and sheep 139 18.32 12.13 2 62 age 139 40.17 8.64 25 6 education 139 1.08 2.22 0 9 number of dead goat 139 .39 .70 0 5 crop income 139 23363.39 23132.78 0 120000 non_farm_i~e 139 1409.28 3747.66 0 21600 family size 139 5.61 1.75 1 14 value of hh asset~t 139 37762.68 123832.4 0 1325100 total land hold~e 139 3.80 9.26 0 100 distance from market 139 19.59 7.75 7 32 number training 139 3.25 1.44 0 7 livestock income~e 139 16797.94 18929.35 0 99755 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 71 cattle 23% sheep 18%goat 44% camel 13% pack animals 2% 59.01% 0.62% 20.50% 0.62% 6.83% 10.56% 0% 1.86% 0% dead of livestock b/s of drought dead of livestock b/c of flooding dead of livestock b/s of communicable diseases dead of livestock b/c of conflict reduction of milk b/c of drought reduction of agricultural harvest b/c of excess rain or drought fall of livestock market price stealing and robbing others 5.59% 46.58% 16.15% 31.06% 0.62% decreasing quantity of food consumed saving and selling home furniture borrowing money from different institutions receiving aid from different go and ngo begging others of the total 165 sampled households, only 139 of them have goat and sheep in fantale woreda. the maximum average willingness to pay for the proposed insurance for goat and sheep is about 21.79 birr per year and the minimum average willingness to pay is 12.41 birr per year. the average population of goat and sheep per head is about 18.32 and the mean age of sampled households for this model is 40.17 years. out of the 165 respondents, majority of the households are farmers followed by pastoralist and some are practicing mixed agriculture. the major livestock population in this karrayyu community are goat and sheep, cattle, camels and other pack animals summarized as in figure 2. figure 2: share of livestock distribution by study area 3.2. severity of shock and mitigation mechanism for both woreda one purpose of the study is to propose livestock insurance scheme for the community in order to be able to cop up with different shocks which pull them into poverty, otherwise. hence, by assessing the type of shock frequently happening in the study area, the severity of this shock is categorized as displayed in figure 3. from figure 3, about 59% of shock is suffered because of drought followed by communicable disease (20.5%) and excess rain (10.5%). the farmers, since long time, have been victim of these shocks and were given that these households are usually victim of drought, over flooding and other are not able to cop up with these shocks. hence this study, for the first time, proposes livestock insurance to safe guard livestock owners against this shock. to recover from problems associated with these shocks, they have been using different mitigation mechanism such as selling their own asset, home furniture; depend on ngo aids and government aids and etc. the mitigation practices are summarized in figure 4. figure 3: severity of shocks by percent figure 4: mitigation practices in the study area jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 72 36.88% 20.63% 2.50% 14.38% 19.38% 3.75% 2.50% 0.00% methods to manage and prevent the risk of livestock based on its… saving more money increasing more saving of crops increase number of livestock decrease number of livestock increase food or drugs of livestock employing one family member on other income generating activity borrowing money from different institution others 0.00% 10.00% 20.00% 30.00% 40.00% majority of the respondents were selling their home furniture to overcome the problem followed by receiving aid from different governmental and nongovernmental organizations. however, this is to be recognized that it cannot be sustainable way of coping up with the problem. therefore, during the study of this work, we have asked the respondents’ means of mitigating the effect of future shocks against their livelihood and the response is summarized in figure 5. as shown in figure 5, farmers mainly wish to save more money and crops to prevent and resist shock respectively. about 36.8% of the respondents wish to reduce risk of their livelihood by saving money followed by increasing crop storage as safe guard during shock (20.6%), and then followed by storing foods of livestock for during drought (19.3%) since major cause of shock is drought as earlier explained. furthermore, we have conducted perception index just to understand farmers’ attitude towards risk. perceptions of risk attitude level across sampled households are different as follows: majority of sampled respondents are risk adverse people. 3.3. information access of farmers and pastoralist the farmers and pastoralist need to get information to sell their livestock in the market. however, the information asymmetry is a big problem in rural community of ethiopia. the karrayyu community mainly get information about their livestock market from local peoples and local market source. the majority of respondent’s source of information about livestock marketing is from local people or neighbour followed by from local market. 3.4. reasons for no –no response (protest) the major reason of the respondents to reject the proposed insurance bid is because they believe that government should pay the insurance bid; while having no money is the second major reason. 3.5. percentage of livestock willing to be insured percentage of camel, cattle and goat and sheep respondents are willing to insure, on average, are given by each kebeles in table 6. majority of the respondents have willingness to insure large share of their cattle followed by goat and sheep. therefore, we can say from the above table that, on average, pastoral community of karayu people are willing to insure more than 40% of their livestock population on very reasonable prices. figure 5: future method to reduce risk of livelihood during shock table 6: percentage of livestock to be insured by kebele laga banti godo faafatee dire saden borokot gari nura dhera total mean mean mean mean mean mean how much percentage of goat and sheep you have wt insure 26.00 59.63 31.20 60.17 51.95 45.79. how much percentage of camel you have wt insure 22.18 39.18 27.27 . . 29.54. how much percentage of cattle you have wt insure 23.00 57.50 28.88 54.43 70.74 46.91. jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 73 3.6. econometrics analysis interval data logit estimation techniques were used to estimate the model of this study i.e to identify determinant factors which affect household wtp and to know how much they are willing to pay to join the proposed livestock insurance. using interval data logit model we have estimated three models i.e. for camel, for cattle and for goat and sheep. in the case of bivariate logit, fixed effect panel and interval logit models (models with two variables as dependent variable), the appropriate estimated parameters used for the interpretations is the marginal effect one, instead of incidental effects and odd ratios. therefore, the below tables are the estimated marginal effect results for each models. the result of camel model (table 7) shows that age of household head, family size, and number of camel size and value of household asset have positive effect on probability to join livestock insurance and more willingness to pay. education has an expected result which implies the more educated the less willing to join insurance but this is because of data problem. we find that educated people are not even living there as a pastoralist or farmers rather they join urban economic activities where there is relatively higher wage rate. the non-farm income and distance from local market has negative impact on willingness to join livestock insurance. this could be because of the fact that the more household earn nonfarm income the more they may perceive to overcome any shock when happened; and hence the more reluctant they are to join livestock table 7: marginal effect result for willingness to pay model for camel insurance variables marginal effects after intreg: dy/dx mean value x starting bid -1.576261*** (.3177338) 50 camels owned .8899253*** (.30587) 13.6383 age .5933122* (.34489) 36.8511 education -6.167751*** (1.44266) .276596 crop income .0001123 (.0001) 22697.4 nonfarm income -.0011565** (.00058) 1067.66 family size 3.050541*** (.85905) 5.76596 value of household asset .0006384*** (.00011) 21249.6 total land hold -1.747564*** (.34872) 21.2979 distance to market -3.76045*** (1.42229) 3.74468 no. of training taken -.0000377 (.00016) 27464.5 livestock income -.5275333 (.62076) 5.44362 lnsigma 1.9253*** (.2062) sigma 6.8569 (1.4141) log likelihood = -18.00532; lr chi2(11) = 60.37; prob > chi2 = 0.0000; no. of observation=47 standard errors in parentheses *** p<0.01, ** p<0.05, * p<0.1 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 74 table 8: marginal effect result for willingness to pay model for cattle insurance standard errors in parentheses *** p<0.01, ** p<0.05, * p<0.1 insurance. the more the distance of market from the household, the less household has money in the pocket; and hence the more reluctant he is willing to pay for livestock health insurance. concerning the number of training they have been attending on livestock management, the negative sign may be attributed deviation of the training to the real situation of that community. the result for the cattle model (table 8) is not as such significant in influencing willingness to pay for livestock insurance. however, the value of household asset has negative impact on willingness to pay for livestock insurance which may imply that as household asset increases people have less willingness to accept new ideas and hence less willingness to join the program. the number of cattle owned has positive impact on willingness to pay and the starting bid has negative impact on households’ willingness to pay for livestock insurance in the study area. the model for goat and sheep is as below table 9. the result of this model shows that as number of goat and sheep increases households willingness to join livestock insurance increases and significant. the higher livestock income leads to the less willingness to pay for goat and sheep insurance. as age of the household increase, their willingness to pay for livestock insurance decreases, which imply aged people, has less tendency to accept new products. in all the three models, the starting bid price has negative significant effect on the demand for livestock insurance, which confirms the law of demand. variables marginal effects after intreg: dy/dx mean of x starting bid -1.401491*** (.3039682) 30 number of cattle owned .4574891* (.26913) 12.1606 age -.2785723 (.1926) 40.0438 education 1.121682 (.75266) 1.10949 income from crop -.000043 (.00007) 23559.7 nonfarm and off farm income -.0004382 (.00038) 1591.9 family size .4678694 (.93423) 5.60584 value of household asset -.0000208* (.00001) 36483.9 total land hold -.1791323 (.17077) 3.82883 distance to market -.0470991 (.22909) 19.4161 number of training taken .9741571 (1.21301) 3.21168 livestock income -3.11e-06 (.00012) 16210.5 lnsigma 2.6561*** (.0749) sigma 14.2401 (1.0666) log likelihood = -139.3593; lr chi2(11) = 16.69; prob > chi2 = 0.1175; no. of obser.=137 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 75 table 9: marginal effect result for willingness to pay for goat and sheep insurance 3.7. total willingness to pay one of the objectives of this study is to know how much of birr households are willing to pay for their livestock insurance. hence to answer for this question, we need to calculate total willingness to pay. to obtain the total willingness to pay for each insurance model for sampled area, we need to know the median or mean willingness to pay per livestock. the mean and median willingness to pay is obtained using krinsky and robb procedure. the total willingness to pay for sampled survey area is calculated as multiplying the percentage of livestock 4 the currency exchange rate during study period was usd 1= 20 birr. willing to be insured by the estimated median willingness to pay. if the sampled households do represent the entire woreda, then out of the total size of livestock 29.54 %, 46.91% and 45.79 % of camel, cattle and goat and sheep’s will be insured, respectively (tabel 10). hence the total willingness to pay for camel, cattle and goat and sheep are 2.7million, 4.27 million, and 4.4 million birr4 per year respectively. this amount of birr implies, as there is huge demand for livestock insurance in this karrayyu community and can call for potential intervention. variables marginal effects after intreg: dy/dx mean of x starting bid -2.157819*** (.4416049) 10 number of goat and sheep owned .1375738** (.06405) 18.3333 age -.1534964* (.08452) 40.1812 education -.2314444 (.31806) 1.08696 income from crop -.0000199 (.00003) 23307.7 nonfarm and off farm income -.000058 (.00018) 1419.49 family size .1606583 (.39725) 5.6087 value of household asset 2.41e-06 (.00001) 37902.3 total land hold -.0358934 (.07617) 3.80797 distance to market -.0334112 (.10176) 19.6812 number of training taken .2823072 (.51282) 3.25362 livestock income -.0001254*** (.00004) 16809.5 lnsigma 1.9063*** (.0709) sigma 6.7279 (.4769) log likelihood = -187.61759; lr chi2(11) = 21.12; prob > chi2 = 0.0322; no. of obser. = 138 jeleta gezahegne et al. ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 76 table 10: total willingness to pay 4. conclusion and recommendation karrayyu communities living in boset and fentale experience recurrent weather related shocks like drought and rainfall failure. given that these communities are largely pastoralists, covariate shocks like drought have paramount effect on the livelihood of these communities. given this condition, the studyanalyzed households’ willingness to pay for index based livestock insurance and the determinants of livestock insurance. the finding of the study shows the presence of huge potential demand for livestock insurance among the karrayyu community. the camel model reveals that age of household, family size, number of camel size and value of household asset have positive effect; non-farm income and distance from local market have negative effect on the households’ probability of joining livestock insurance and their wtp. the cattle model shows that age of household head has negative impact on livestock insurance. the result of goat and sheep model shows number of goat and sheep has positive and significant effect while income from livestock has negative effect on households’ willingness to join livestock insurance. in all models, the starting bid price has negative significant effect on the demand for livestock insurance, confirming the law of demand. based on the study results, the author recommends the following main points;  the fact that there is willingness to pay for livestock insurance implies that policy intervention through supply of livestock insurance can mitigate the side effect of covariate shocks leading to smooth consumption and stable income stream of households.  the fact that the median wtp for a single camel is greater than other livestock implies that preferential policy intervention, through camel insurance, may yield better outcome as community give more value to the camel.  majority of the households who reject to pay for the proposed new insurance scheme perceive that government should pay premium for them and hence may partly imply lack of awareness and hence awareness creation is need to be done.  the fact that the finding shows households’ source of market information is from local people, implies that their access to information is very limited. therefore, working for households’ better access to information through radio and other forms of communication is crucial. acknowledgment first, we would like to express our deep heartfelt gratitude to adama science and technology university for granting this research paper. in addition, we would like to extend our thanks to boset and fentale agricultural office workers who helped in collecting the data. reference ali, d.a., deininger, k., and duponchel, m. 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(2011). quantifying vulnerability to climate change: implications for adaptation assistance. center for global development working paper no.240 19 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu research paper investigation of reinforced concrete columns confined by rectangular spiral reinforcement using finite element analysis thomas belete1,, nigatu chaffo2, habtamu melese1, bobby lupango1 1civil engineering department, institute of technology, arba minch university, arba minch, ethiopia 2ministry of urban development and construction, addis ababa, ethiopia article info abstract article history: received 02 sept. 2020 received in revised form 02 february 2021 accepted 15 february 2021 the load carrying and deformation capacity of square reinforced concrete (rc) column confined by rectangular spiral lateral reinforcement subjected to axial load were investigated numerically using abaqus. thirty one short square rc columns were modeled where seventeen had conventional hoop tie and the remaining fourteen columns had rectangular spiral lateral reinforcement configuration. the configuration, amount and spacing of the lateral reinforcement were included as a factor of confinement in the investigation. different amounts of lateral reinforcement including 1.4%, 1.6%, 1.8%, 2% and 2.3% were provided in the investigated columns. the diameters of lateral reinforcement used for confinement purpose were 6 mm, 8 mm and 10 mm. the primary objective of this study was focused on the investigation of confinement effect of continuous lateral reinforcement configuration in terms of stress carrying and deformation capacity of confined reinforced concrete columns. rc columns confined with either configuration (hoop or spiral) of lateral reinforcement and provided with amount of reinforcement in the range of 1.6% to 2% where the spacing to core depth (s/dc) ratio was maintained in the range of 0.4-0.5 had exhibited improved deformation and stress capacity. accordingly, confined rc columns with rectangular hoop lateral reinforcement had 12% and rc columns with continuous spiral lateral reinforcement had 40% higher deformation capacity compared to rc columns with the same amount and configuration of lateral reinforcement but where the spacing was in such a way s/dc ratio was ≥ 0.5. clearly, the use of rectangular spiral reinforcement as lateral reinforcement could be considered as a better alternative for lateral reinforcement of short square rc columns particularly, where the deformation capacity is the main importance. keywords: confinement deformation capacity rc column spiral reinforcement 1. introduction the ability of structural element to withstand the load imposed on without significant deformation maintains the stability of the structure. in skeletal frame structure, local failure (plastic hinge) in column intercepts the flow of load transfer leading to partial or global collapse of structure. hence, the ductile behavior of column is required critically for avoiding formation of plastic hinge in the column. due to this reason, several national codes (aci-318-08, 2008; es en corresponding author, e-mail: fanaisat@gmail.com https://doi.org/10.20372/ejssdastu:v8.i2.2021.291 1998-1: 2013) had incorporated strong column-weak beam design philosophy and the flexural strength ratio of column to beam (∑ 𝑀𝑐 / ∑ 𝑀𝑏) ≥ 1.2 set to realize the above requirement. an effort to enhance the strength and ductility of the column member has led to the application of confinement. the research on the confinement of rc column member around the globe could be classified into two categories. http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i2.2021.291 thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 20 the first category includes research studies incorporating additional materials to enhance the strength and ductility of rc column member. these are studies on rc column member confined by fiber reinforced polymer (frp) (ali et al., 2018), and the application of buckling restraint reinforcement (brr) (lukkunaprasit et al., 2011). however, the additional cost of these materials, installation and availability hinder the applicability of these confinement techniques in ordinary column construction. the second category is a widely practiced lateral reinforcement confinement. the pioneer works of rechart et al. (1929) demonstrated steel lateral reinforcement had significantly improved the strength and ductility of axially loaded rc column. since then sheikh (1983), mander et al. (1989) and sheikh and yeh (1990) had conducted investigation on the effect of lateral reinforcement confinement on rc column. sheikh (1983) identified core concrete area, nominal strength of lateral reinforcement and concrete, spacing and amount of reinforcement, and tie configuration as the primary factors affecting the confinement in rc column. mander et al. (1989) considered the reduced core concrete area in the development of analytical model for strength and ductility of confined concrete. sheikh and yeh (1990) investigated rectangular rc column and mentioned that inadequate configuration of lateral reinforcement had resulted in unstable strength degradation on the post–peak behavior of stress–strain curve for tested rc column. saaticoiglu and razvi (1992) pointed out that the non-uniformity of confinement stress at a tie level and along the rc column height reduced the improvement on the strength and ductility of confined concrete. sheikh and toklucu (1993) investigated circular rc column, and pointed out the contribution of an optimum combination of the spacing and amount of reinforcement for enhanced strength and ductility of confined concrete. the shape of the cross-section of the member under consideration had significant effect on the effectiveness of confinement provided to the core concrete (mander et al., 1989; saaticoiglu and razvi, 1992). studies on circular rc column revealed that both spiral and hoop configurations had resulted in significant enhancement of ductility and strength of the member (mander et al., 1989; sheikh and toklucu, 1993). whereas, on rectangular rc column or generally edged cross section the nonuniform confinement pressure both at tie level and along the height of column had reduced the enhancement on load carrying and deformation capacity of the column. sheikh and yeh (1990) and zeng (2017) demonstrated the use of various configurations such as diamond and other shapes to eliminate the non– uniformity at a tie level and also suggested the use of additional longitudinal bars in between corners of edged cross section rc columns. however, apart from close spacing of lateral reinforcement as means to minimize the non-uniformity of confinement yet no investigation was availed on the effectiveness of continuous confinement in reducing the non–uniformity of confinement pressure along the length of square rc column. since recent times, several studies have been conducted on the use of rectangular spiral reinforcement (rsr) in rc beam–column joint. karayannis and sirkelis (2005) and saha and meesaraganda (2018) conducted experimental investigation on rc beamcolumn joint subjected to cyclic load. these studies mentioned that the use of rsr enhanced the shear capacity of the joint. it was also observed that the crack propagation through the joint was delayed. athira and remya (2017) numerically investigated beam-column joint subjected cyclic load and mentioned that spirally tied beam-column joint had exhibited improved energy absorption capacity. however, studies focused on the load carrying behavior of square rc column confined by rsr and subjected to axial loading were not or rarely available yet. hence, study had focused on the confinement effect of continuous spiral lateral reinforcement on the stress and deformation capacity of square short rc column subjected to axial load. the continuous configuration of rectangular spiral reinforcement expected to eliminate the problem related to non-uniformity of confinement along the length of square/rectangular rc column. therefore, the main objective of this research was focused on the investigation of the effect of spiral lateral reinforcement on the strength and deformation capacity of square short rc column subjected to axial load. in addition, the effect of considerable factors affecting rc column confinement including the amount and spacing of traverse reinforcement was investigated. finally, the enhancement in load carrying capacity and deformation capacity due to rectangular spiral configuration was thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 21 examined in comparison with the conventional (discrete hoop) configuration of the lateral reinforcement. 2. materials and methods 2.1. materials two materials, concrete and reinforcing bar were required to model the rc column in the computer program (abaqus). these two materials were assembled together and a model of rc column was created in the analysis program. the mechanical property of the materials, their interaction, load and boundary condition were simulated to reflect the actual as constructed rc column. the mechanical properties of both materials were taken from national code mainly es en 1992-1-1: 2013, from manuals of analysis program and research papers. es en 1992-1-1: 2013, classifies concrete into several strength classes based on 28 days characteristic compressive cylinder strength. table-2 summarizes the mechanical properties of concrete and steel reinforcement that were used for modeling specimens in this study. uniaxial compressive stress–strain relationship was obtained from the analytical model recommended by es en 1992-1-1: 2013. the non-linear quasi-brittle mechanical behavior of concrete was defined according to concrete damage plasticity (cdp) model. the elastic nature of both tensile and compressive behavior is defined by modulus of elasticity (ecm) and poisons ratio (ν=0.16) (abaqus get started user’s manual, 2014). the inelastic behavior is obtained by subtracting the elastic behavior from the total uniaxial stress–strain relationship (abaqus user’s manual, 2014). the stiffness degradation beyond the elastic range was characterized by tension (dt) and compression damage (dcm) variables (abaqus user’s manual, 2014). the cdp model in abaqus defines yield criteria using plastic strain in compression and tension (abaqus user’s manual, 2014). other parameters related to concrete flow properties including eccentricity, the ratio of equibiaxial compressive yield stress to uniaxial compressive yield stress (kc) and the ratio of stress invariant on tensile to stress invariant on compression (σbo/σco) (table 1) were taken from abaqus-6.14 user’s manual (abaqus user’s manual, 2014). others parameters including poison’s ratio, dilatation angle and viscosity parameter were determined based on convergence and validation test and were summarized in (table 2). table 1: flow parameters in concrete damage plasticity model dilatation angle kc 𝜎𝑏𝑜 /𝜎𝑐𝑜 eccentricity (𝜀) viscosity 31o 0.67 1.16 0.1 0.0001 table 2: properties of material used . material yield strength (mpa) diameter (mm) modulus of elasticity (gpa) poison’s ratio 1 concrete 25 31.5 0.16 2 steel long. rein. 400 16 200 0.3 lat. rein. 400 6-10 200 0.3 the yield strength (fy) = 400 𝑀𝑝𝑎 was considered for both lateral and longitudinal steel reinforcement. the nominal elastic stress–total strain relation was determined using the analytical expression from en 1992-1-2:2004. the elastic behavior up to the yield stress is defined by specifying the modulus of elasticity, 𝐸𝑠 = 200 𝐺𝑃𝑎 and 𝜈 = 0.3 for poison’s ratio. the inelastic behavior was obtained by subtracting the elastic behavior from the total uniaxial stress–strain relationship (abaqus user’s manual, 2014). 2.2. method the investigation was conducted through the use of a computer program, abaqus. in this work pin supported short, square rc columns subjected to axial load were modeled and simulated in the abaqus/standard analysis product. and the results of analysis were used to investigate the effect of the study variables namely amount, spacing and configuration of lateral reinforcement on load carrying and deformation capacity of rc column. a total of thirty one specimens were modeled (figure 1) and submitted into computer program namely abaqus and the result of all thirty one specimens were considered in the investigation. all specimens had the same size dimension 200 x 200 x 1000 mm. the concrete cover was provided according to the provision of en 1992-1-1:2004 for minimum concrete cover. accordingly 25 mm thick concrete cover was provided on each sides of the rc column. the middle region extending over 250 mm length was identified as test region where the remaining top and bottom was strengthened by doubling the amount of reinforcement to avoid premature failure. thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 22 figure 1: typical model of investigated rc columns figure 2: typical cross-section of investigated rc columns table 3: summary and detailed data of tested specimens s. no. category specimen lat. rein. configuration lat. rein. spacing (mm) s/dc ratio amount of lat. rein. (ρs) in (%) bar dia. of llat. rein.(mm) 1 group 1 r50am14 hoop tie 50 0.33 1.4 6 r90am14 " 90 0.6 8 r140am14 " 140 0.93 10 s50am14 spiral 50 0.33 6 s90am14 " 90 0.6 8 3 group 2 r45am16 hoop tie 45 0.3 1.6 6 r60am16 " 60 0.4 7 r80am16 " 80 0.53 8 r120am16 " 120 0.8 10 s45am16 spiral 45 0.3 6 s60am16 " 60 0.4 7 s120am16 " 120 0.8 120 3 group 3 r40am18 hoop tie 40 0.27 1.8 6 r60am18 " 60 0.4 7.4 r80am18 " 80 0.53 8 r110am18 " 110 0.73 10 s40am18 spiral 40 0.23 6 s60am18 " 60 0.42 7.4 s110am18 " 110 0.73 33 10 4 group 4 r35am20 hoop tie 35 0.23 2.0 6 r60am20 " 60 0.4 8 r100am20 " 100 0.67 10 s35am20 spiral 35 0.23 6 s60am20 " 60 0.4 8 s100am20 " 100 0.67 10 5 group 5 r30am23 hoop tie 30 0.2 2.3 6 r55am23 " 55 0.37 8 r85am23 " 85 0.57 10 s30am23 spiral 30 0.2 6 s55am23 " 55 0.37 8 s85am23 " 85 0.57 10 core depth (dc = 150mm) thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 23 the typical cross-section for all investigated rc column specimens was given in figure 2 and for all columns 16 mm diameter longitudinal bars were assumed in assembling the column model. at a time all variables reasonably were kept constant except the variable to be studied. the investigated column specimens vary either in amount, spacing or configuration of the lateral reinforcement. in assembling most columns, commonly known diameters of lateral reinforcement (table 3) were used but, on few columns where particular spacing of lateral reinforcement was needed for comparison, unfamiliar diameters of lateral reinforcement were assumed for analysis purpose. sheikh and toklucu (1993) mentioned that for amount of lateral reinforcement ≤ 1% and ≥ 2%, changing the spacing of lateral reinforcement had no significant effect on stress– strain relationship of axially loaded rc column. in this research, in order to have enough data for comparative investigation, the columns with five different amounts of lateral reinforcement including (1.4%, 1.6%, 1.8%, 2% & 2.3%) were investigated. the spacing of lateral reinforcement was determined using equation 1 and it is a function of amount of lateral reinforcement (ρs), core depth of the column cross-section (dc) and cross-sectional area of the lateral reinforcement (as). at a time one amount of lateral reinforcement (ρs) was selected and kept constant, and since the cross-section of all columns was constant, the spacing of lateral reinforcement was varied through altering the diameter (db) or cross-sectional area (as) of the lateral reinforcement. 𝑆𝑝𝑎𝑐𝑖𝑛𝑔 (𝑠) = 4𝑎𝑠(𝑑𝑐 − 𝑑𝑏 ) 𝜌𝑠 𝑑𝑐 2 … … … … . (1) the name of model specimens (table-3) follows from spacing, configuration and amount of reinforcement. for instance, in designation of specimen r40am18: r stands for rectangular hoop configuration, 40 stands for spacing in mm and am18 indicate the amount of lateral reinforcement in percent (ρs = 1.8%). similarly, in designation of specimen s60am18: s stands for continuous spiral configuration, 60 stands for spacing in mm and am18 indicate the amount of reinforcement in percent (ρs = 1.8%). 3. result and discussion specimens with different amount of reinforcement and spacing had been modeled and analyzed using the computer analysis programabaqus 6.14. the analysis result for different comparable rc column models were contrasted with each other, mainly based on the maximum stress developed on the test region of rc column, the strain at maximum stress, and overall nonlinear stress–strain curve behavior. in general, the investigated models could be identified as model with continuous spiral and hoop tie lateral reinforcement based on the lateral reinforcement configuration. as it will be discussed in the proceeding section, varying the spacing of lateral reinforcement for the amount of reinforcement (ρs) ranging from 1.6% − 2% had a significant effect on stress-strain behavior of rc column particularly on post peak stress-strain curve behavior. 3.1. effect of lateral reinforcement spacing the stress-strain diagram (figure 3 through 12) show the effect of lateral reinforcement spacing with respect to the amount of lateral reinforcement. reducing the spacing almost by half such that from 90 mm to 50 mm had no significant effect on stress carrying and deformation capacity of both (r90am14 and r50am14) tested columns, indeed the stress–strain curve of each column overlap over each other (figure 3) and both columns attain peak stress at the same strain (table 4). similarly, in spiral tied specimen with amount of lateral reinforcement 1.4%, column s50am14 and s90am14 where the lateral reinforcement spacing was 50mm and 90mm respectively, both had nearly the same peak stress (figure 4) and attained the peak stress at the same strain. thus, reducing the spacing between lateral reinforcement for specimens with amount of reinforcement 1.4% had insignificant improvement on the stress and deformation capacity of tested confined concrete rc column specimens. the effect of lateral reinforcement spacing was more significant on columns with amount of reinforcement in the range of 1.6-2%. figure 3: stress-strain curve for hoop tied specimen (ρs = 1.4%) 0.0 10.0 20.0 30.0 40.0 0 0.005 0.01 0.015 0.02 0.025 strain r50am14 r90am14 r140am14 s tr e ss ( m p a ) thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 24 0 10 20 30 40 0 0.005 0.01 0.015 0.02 0.025 s tr e ss ( m p a ) strain r45am16 r60am16 r120am16 r80am16 0.0 10.0 20.0 30.0 40.0 0 0.005 0.01 0.015 0.02 0.025 strain s60am18 s40am18 s110am18 s tr e ss ( m p a ) figure 4: stress-strain curve for spirally tied specimen (ρs = 1.4% figure 5: stress-strain curve for hoop tied specimen (ρs = 1.6%) figure 6: stress-strain curve for spirally tied specimen (ρs = 1.6%) figure 7: stress-strain curve for hoop tied specimen (ρs = 1.8%) figure 8: stress-strain curve for spirally tied specimen (ρs = 1.8%) figure 9: stress-strain curve for hoop tied specimen (ρs = 2%) figure 10: stress-strain curve for spirally tied specimen (ρs = 2% figure 11: stress-strain curve for hoop tied specimen (ρs = 2.3%) s tr e ss ( m p a ) 0 10 20 30 40 0 0.01 0.02 0.03strain s50am14 s90am14 s tr e ss ( m p a ) 0 10 20 30 40 0 0.005 0.01 0.015 0.02 0.025 strain s60am16 s45am16 s120am16 0.0 10.0 20.0 30.0 40.0 0 0.01 0.02 0.03 strain r40am18 r60am18 r110am18 r80am18s tr e ss ( m p a ) 0.0 10.0 20.0 30.0 40.0 0 0.005 0.01 0.015 0.02 0.025 strain r60am20 r100am20 r35am20 s tr e ss ( m p a ) 0.0 10.0 20.0 30.0 40.0 0 0.01 0.02 0.03strain s100am20 s60am20 s35am20 s tr e ss ( m p a ) 0.0 10.0 20.0 30.0 40.0 0 0.005 0.01 0.015 0.02 0.025strain r55am23 r85am23 r30am23 s tr e ss ( m p a ) thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 25 table 4: summary of values on the stress-strain curve for specimens (ρs = 1.4%) s. no. specimen name max. stress (mpa) strain at max stress strain at 85% of max stress strain ductility ratio 1 r50am14 34.76 0.0024 0.0165 6.9 2 r90am14 34.46 0.0024 -- 3 r140am14 33.66 0.0023 0.0062 2.7 4 s50am14 34.35 0.00234 0.0115 4.9 5 s90am14 34.44 0.00234 -- -= stress capacity not reduced to 85% of the maximum stress figure 12: stress-strain curve for spirally tied specimen (ρs = 2.3%) as summarized in table 5, column specimens (r45am16, r60am16 and r120am16) had nearly the same peak/maximum stress, however indispensable enhancement was observed on the strain at which the peak stress was attained. specimen r60am16 attain peak stress at 12.5% higher strain compared to strain at peak stress in specimen r120am16 respectively. similarly, in spirally tied specimen the peak stress for specimen s60am16 was 2.3% higher compared to the peak stress for specimen s120am16. regarding the deformation capacity, the strain at peak stress for specimen s60am16 was 54.5% higher (table 5) than the strain at peak stress for specimen s120am16. in specimen under group-3, with 1.8% lateral reinforcement, reducing the spacing from 110 mm in specimen r110am18 to 60mm in specimen r60am18 resulted in 2% higher peak stress and offset the strain at peak stress by 12.5% (table 6) compared to that in specimen r110am18. similarly, in spirally tied specimen, the peak stress and strain at peak stress in specimen s60am18 was 2.6% and 12.5% higher (table 6) compared to that in specimen s110am18, respectively. table 5: summary of values on the stress-strain curve for specimens (ρs = 1.6%) s. no. specimen name max. stress (mpa) strain at max. stress strain at 85% of max. stress strain ductility ratio 1 r45am16 34.92 0.00244 0.0092 3.77 2 r60am16 35.08 0.0026 0.0115 4.423 3 r80am16 34.77 0.00245 0.0143 5.84 4 r120am16 34.63 0.00231 0.0189 8.2 5 s45am16 34.94 0.00254 0.0082 3.23 6 s60am16 35.2 0.00377 0.0087 2.31 7 s120am16 34.4 0.00244 0.0132 5.41 table 6: summary of values on the stress-strain curve for specimens (ρs = 1.8%) s. no. specimen name max. stress (mpa) strain at max stress strain at 85% of max stress strain ductility ratio 1 r40am18 35.25 0.0025 0.0106 4.24 2 r60am18 35.4 0.0027 0.01 3.7 3 r80am18 35.06 0.0024 0.0097 4.04 4 r110am18 34.73 0.0024 0.0093 3.87 5 s40am18 34.35 0.00234 0.0084 3.6 6 s60am18 35.38 0.0027 0.0083 3.07 7 s110am18 34.5 0.0024 0.0094 3.92 0.0 10.0 20.0 30.0 40.0 0.00 0.01 0.01 0.02 0.02 0.03 strain s30am23 s85am23 s55am23 s tr e ss ( m p a ) thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 26 the same trend was observed on columns with 2.0% lateral reinforcement, the peak stress in specimen r60am20 was 2.2% higher compared to peak stress in r100am20 and the strain at peak stress was enhanced by 10% (table 7) than that in specimen r100am20. similarly, in spirally tied specimen s60am20 with reduced lateral reinforcement spacing had 2.6% higher peak stress capacity than that of comparable specimen s100am20 (table 7) and offset the strain at peak stress by 54% compared to that in specimen s100am20. in case of specimens with amount of reinforcement 2.3%, the peak stress in specimen r55am23 was 0.8% higher than the peak stress in specimen r85am23, and the strain at peak stress was enhanced by 8.3% (table8) compared to the strain at peak stress in specimen r85am23. similarly, in spirally tied specimen both (s55am23 and s85am23) had equal peak stress and the strain at peak stress for specimen s55am23 was 7% (table 8) higher than that in specimen s85am23. clearly the enhancement of stress and deformation capacity through reducing lateral reinforcement was lower in specimens with 2.3% lateral reinforcement compared to the enhancement on specimens included in group 2 4 with 1.6% 2% reinforcement. on the other hand, reducing the lateral reinforcement spacing beyond certain limit had no significant effect on the stress carrying and deformation capacity of confined concrete. as shown in table 5, specimens r60am16 with wider spacing had relatively higher stress capacity and the strain at peak stress was 6.5% higher compared to specimen r45am16 which had close spacing of lateral reinforcement. the same result was observed on columns with 1.8% lateral reinforcement. the stress-strain diagram (figure 7 & 8) for specimen r60am18 and s60am18 with wider spacing than r40am18 and s40am18 respectively had exhibited similar stress strain curve, indeed specimen r60am18 and s60am18 attain peak stress at comparatively larger strain (table 6). thus, reducing the lateral reinforcement spacing beyond certain limit such that s/dc ratio less than (≤0.35) couldn’t enhanced the stress and deformation capacity of tested columns with both configurations. the results observed on columns with 2.0% and 2.3% lateral reinforcement bear a witness to the same conclusion. as shown in table 7, specimens r60am20 and s60am20 with wider spacing of lateral reinforcement had the same peak stress capacity compared to the corresponding specimens r35am20 and s35am20, respectively. indeed, the strain at peak stress in specimen s60am20 and r60am20 was 4% and 8% higher compared to the peak stress in s35am20 and r35am20, respectively. actually, specimen s30am23 had 10% and 70% higher peak stress and strain at peak stress, respectively (table-8) compared to that of specimen s55am23. however, the rapid strength degradation on the falling branch of the stress-strain curve reduced the significance of reducing the lateral reinforcement in columns with the amount of reinforcement 2.3%. hence, the selection of lateral transverse reinforcement spacing should consider the important outcome due to redistribution of forces through deformation. it was noted that, specimens r80am16 and r80am18 with lower spacing (s/dc = 0.53) had exhibited no significant improvement on load carrying and deformation capacity relative to comparable specimens r120am16 (s/dc = 0.8) and r110am18 (s/dc = 0.73), respectively. thus, more reduction of the lateral reinforcement could not cause significant improvement on stress and deformation capacity of the investigated column specimens. therefore, an optimum combination of spacing and amount of lateral reinforcement had to be provided to improve the load carrying and deformation capacity of axially loaded rc column. referring to the cases observed on specimen with lateral reinforcement of 1.4%, 1.6%, 1.8%, 2% and 2.3%, reducing the spacing of lateral reinforcement had significant effect on the stress and deformation capacity such that, for the amount of reinforcement in the range of 1.6% 2 percent. reducing the spacing where the amount of reinforcement was in the mentioned range, improved the peak stress capacity, on average by 2.3% and enhanced the strain at the peak stress, on average, by 12% and 40% in hoop tied and rectangular spiral tied square rc column specimens respectively. the spacing to depth (s/dc) ratio of these specimens was existed in the range of 0.4-0.5. clearly, the rectangular spiral configuration of lateral reinforcement had contributed to the observed higher deformation capacity of investigated confined rc column specimens. spiral configuration of the lateral thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 27 table 7: summary of values on the stress-strain curve for specimens with (ρs = 2%) s. no. specimen name max. stress (mpa) strain at max. stress strain at 85% of max. stress strain ductility ratio 1 r35am20 35.56 0.00245 0.0081 3.3 2 r60am20 35.7 0.00265 0.0092 3.5 3 r100am20 34.88 0.0024 0.0094 3.92 4 s35am20 35.6 0.00356 0.0075 2.07 5 s60am20 35.84 0.0037 0.0077 2.08 6 s100am20 34.64 0.0024 0.0097 4.04 table 8: summary of values on the stress-strain curve for specimens with (ρs = 2%) s. no. specimen name max. stress (mpa) strain at max. stress strain at 85% of max stress strain ductility ratio 1 r30am23 36.0 0.00367 0.0077 2.88 2 r55am23 35.8 0.0026 0.0097 3.5 3 r85am23 35.5 0.0024 0.0082 3.4 4 s30am23 36.2 0.0041 0.0073 2.07 5 s55am23 35.87 0.0026 0.0082 3.15 6 s85am23 35.4 0.00243 0.0083 3.4 reinforcement had favorable inclination to delay the inclined crack propagation that was likely to ensue after enough disintegration of the core concrete had taken place. to the effect, comparatively extended yielding plateau was observed on the stress-strain curve (figure 6, 8 & 10) plotted for spirally tied columns. clearly, the effect of reducing the spacing of the lateral reinforcement was more significant on enhancing the deformation capacity than improving the strength of confined concrete. several studies (rechart et. al, 1929; saaticoiglu and razvi, 1992; mohammadreza and mohammadehsan, 2017) mentioned that the conception of failure in confined concrete begins at the same level of load and strain to that of plain concrete. this implied that the confinement through the lateral reinforcement became effective after enough disintegration of core concrete had taken place. however, due to confinement the disintegration of core concrete was delayed and the concrete member was enabled to sustain maximum stress while undergoing degrading strain deformation. the stress-strain diagram plotted on (figure 3 through to 12) had confirmed the same observation. prior to the attainment of the maximum stress, columns with different lateral reinforcement spacing had overlapping stress-strain relationship and exhibited their respective unique path on the descending branch of the stress strain curve. thus, the effect of the confinement was observed on the descending branch of the stress strain diagram such that the lateral reinforcement became effective after the attainment of the maximum stress capacity of the core concrete. hence, once the maximum stress was attained, the increment on the stress capacity was no more significant and the enhancement on deformation capacity, as a result of adequate confinement was more pronounced than the improvement on stress carrying capacity of the investigated columns. 3.2. buckling mode of longitudinal reinforcement and spacing of lateral reinforcement several studies (sheikh and yeh, 1990; rajput and sharma, 2018) had mentioned that the disintegration of core concrete and buckling of the longitudinal bar were the major causes for failure of reinforced concrete column member subjected to higher loads. the buckling modes of longitudinal reinforcement for various representative column specimens were shown in figure 13 through to 18. invariably, sheikh and yeh (1990) and sheikh and toklucu (1993) mentioned that under applied axial load, unreasonably close spacing of lateral reinforcement tends to temporarily restrain buckling of the longitudinal reinforcement. at the same time the ensued confinement had restrained the expansion of the core concrete up to higher concrete strain deformation leading to sudden and localized buckling of longitudinal reinforcement (sheikh and yeh, 1990). thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 28 this case was more clearly observed on column specimens with 2.3% lateral reinforcement where the spacing of the lateral reinforcement was in such a way that s/dc was ≤ 0.35. accordingly, in column specimen s30am23, the closer spacing of lateral reinforcement and relatively higher amount of lateral reinforcement had prevented gradual buckling of longitudinal bar and limited the buckling to few spacing (figure 14) of transverse bar (localized failure). testifying the same observation, the stress-strain curve (figure 12) behavior for column specimen s30am23 had exhibited rapid strength degradation on the falling branch of the curve. on the other hand, in column specimens where amount of reinforcement was ≥1.6% and the spacing of transverse bar was in such a way that s/dc ratio was ≥0.5, buckling of longitudinal reinforcement at relatively lower concrete strain had reduced the stress and deformation capacity of confined concrete. as a result figure 13: undeformed shape of the reinforcement embedded in specimen s30am23 figure 14: deformed shape of the reinforcement embedded in specimen s30am23 figure 15: undeformed shape of the reinforcement embedded in specimen r60am18 figure 16: buckling mode of the reinforcement embedded in specimen r60am18 figure 17: undeformed shape of the reinforcement embedded in specimen r120am16 figure 18: buckling mode of the reinforcement embedded in specimen r120am16 thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 29 the peak stress in these specimens was attained at strain less than 0.24% (table 4-8) which was relatively lower strain compared to the strain of specimen with the same amount but, with closer spacing of lateral reinforcement. in these specimens, buckling of longitudinal reinforcement was due to the lack of support at relatively lower concrete strain of the core concrete. conformably, the mode of buckling of the longitudinal reinforcement (figure 18) for column specimen r120am16 (s/dc ≥ 0.5) had clearly demonstrated that buckling of longitudinal reinforcement was appeared over the length where no lateral bars support was provided. thus, inadequate support for longitudinal bar failed to delay severe buckling of longitudinal reinforcement leading to reduction of load carrying capacity of rc column member. in contrast buckling of longitudinal reinforcement that was observed in figure-16 range over several spacing of lateral reinforcement and hence, gradual buckling of longitudinal reinforcement. consequently, column specimens in group 2 4, where the ratio of the spacing to core concrete dimension (s/dc) was in the range of 0.4 − 0.5, had exhibited enhanced overall stress -strain curve behavior for confined concrete. accordingly detailed specimens in group-2 (figure 5 and 6), group-3 (figure 7 and 8) and group-4 (figure 9 and 10) had exhibited stress-strain curve with considerable yielding plateau, particularly spirally tied specimens had extended yielding plateau after the attainment of the maximum stress. 3.3. strain ductility in this study, the strain ductility ratio was calculated from the ratio of the strain corresponding to 85% of the peak stress on the descending branch to the strain at peak stress (table 4-8) for each investigated rc column specimen. as it could be observed the conclusion based on the strain ductility alone would lead to misinterpretation of the analysis result. for instance, specimen s60am20 and s100am20 in group-4 have 2.1 and 4 strain ductility, respectively. thus, specimen s100am20 with higher strain ductility expected to have higher stress sustaining performance and better stress-strain relationship compared to specimen s60am20. however, specimen s60am20 has 3.5% higher stress capacity and the strain at peak stress in specimen s60am20 was 54% higher than that of specimen s100am20. in addition, at their respective strain at 85% of the peak stress on the descending branch both specimens possess nearly equal strain capacity. thus, the higher strain ductility observed on specimen s100am20 did not necessarily to mean the specimen had better stress and deformation capacity. 4. conclusion and recommendation axially loaded confined rc column specimens with s/dc ratio in the range of 0.4–0.5 and amount of transverse reinforcement in the range of 1.6% – 2% had exhibited better non-linear stress-strain curve behavior. accordingly, confined rc columns had enhanced stress and deformation capacity. the stress-strain for these columns had exhibited yielding plateau observed after the attainment of the maximum stress such that the column had the capacity of sustaining maximum stress while undergoing strain deformation. accordingly, detailed spirally tied square rc columns had 2.6% and 40% higher stress and deformation capacity than comparable tested rc column specimens. whereas, detailed hoop tied rc columns had 2.3% and 12% higher stress and deformation capacity than comparable tested rc column specimens. clearly, in both cases the enhancement on deformation capacity, due to adequate confinement was more considerable than the improvement on stress carrying capacity of the confined concrete. it was also noted that the rectangular spiral configuration of the lateral reinforcement had more significant enhancement on the axial deformation capacity compared to the enhancement due to rectangular hoop tie configuration. lower amount of lateral reinforcement (≤ 1.4%) failed to provide sufficient confinement to core concrete as a result; the peak stress was attained at comparatively low strain. on the other hand, column specimens with higher amount of lateral reinforcement (≥ 2.3%) where the spacing was provided in such way s/dc ratio was ≤ 0.35 had experienced over confinement that hindered gradual buckling of longitudinal reinforcement. as a result, sudden and localized buckling of longitudinal reinforcement had caused rapid strength degradation of confined concrete as such exhibited on the falling branch of stress-strain diagram of accordingly detailed column specimens. whereas, in rc column members where tie spacing exceeded half (s/dc ≥ 0.5) of the core dimension, the peak stress capacity of confined concrete was attained at thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 30 early stage of concrete strain (nearly similar to plain concrete). in this case the major cause for the immediate reduction of stress capacity that was observed after the attainment of the peak stress was due to the lack of adequate lateral ties that could delay the buckling of longitudinal bars. by contrast, in column specimens with amount of transverse reinforcement in the range of 1.6%–2%, where the spacing was in such a way s/dc ratio was in the range of 0.4-0.5, the buckling of the longitudinal reinforcement had taken over comparatively extended length and hence accounted for gradual loss of the load carrying capacity of accordingly detailed column specimens. rectangular spiral configuration of lateral reinforcement could be considered as a better alternative particularly, where deformation capacity of rc column is the main concern. in either (hoop or spiral) case of lateral reinforcement configuration, provided that adequate amount of lateral reinforcement ratio, the spacing of lateral reinforcement ratio should not exceed half of the core dimension (s/dc≤0.5) particularly where deformation capacity is the main importance. this requirement is consistent with the requirement of ethiopian building code for rc column where medium and high ductility class column is to be constructed. on the other hand, for axially loaded rc column with ≥ 2% lateral reinforcement, spacing of lateral reinforcement in such a way that s/dc is ≤0.35 of core dimension should be avoided. rc columns detailed with such closer spacing had experienced over confinement that had caused sudden and localized buckling of longitudinal reinforcement, which was not a desirable behavior for load carrying rc columns. reference aci-318-08 (2008). building code requirement for structural concrete: aci 318-08. 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(2013). es en 1992-1-1: 2013 design of concrete structures. addis ababa, ethiopia: author. karayannis, g. & sirkelis, m. (2005, september 15-17). seismic behavior of reinforced concrete columns with rectangular spiral shear reinforcement [paper presentation]. third international conference on construction in the 21st century (citc-iii) advancing engineering, management and technology. athens, greece. lukkunaprasit, p., tangbunchoo,t., & rodsin, k. (2011). enhancement of seismic performance of reinforced concrete columns with buckling-restrained reinforcement. engineering structures, 33(12): 3311–16. mander, j., priestley, m., & park, r. (1989). theoretical stress -strain model for confined concrete. journal of engineering structures asce, 114(8): 1804–26. mohammadreza, z. & mohammadehsan, z. (2017). evaluation of reinforced concrete columns under biaxial bending. journal of sustainable development, 10(2): 228-237. paultre, p. & légeron, f. (2008). confinement reinforcement design for reinforced concrete columns. journal of structural engineering asce, 134(5): 738-749 rajput, a. & sharma, k. (2018). seismic behavior of under con fi ned square reinforced concrete columns. elsevier structures, 13, 26–35. rechart, f., brandtzaeg, a. & brown, r. (1929). the failure of plain and spirally reinforced concrete in compression.urbana: university of illinois. saaticioglu, m. & razvi, s. (1992). strength and ductility of confined concrete column. journal of structural. engineering asce, 118(6): 1590-1607. saha, p. & meesaraganda, l. (2019). experimental investigation of reinforced scc beam-column joint with rectangular spiral reinforcement under cyclic loading.construction and building materials, 201, 171–85. sheikh, sh. (1983). a comparative study of confinement models. aci structural journal, 79(30): 296-306. sheikh, sh. & yeh, ching-chung. (1990). tied concrete columns under axial load and flexure. aci structural journal, 116(10): 2780–2800. sheikh, sh. & toklucu, m. (1993). reinforced concrete columns confined by circular spirals and hoops. aci structural journal, 90(56): 543-553. tanaka, h. (1990). effect of lateral confining reinforcement on the ductile behavior of reinforced concrete [unpulished phd thomas belete et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 31 thesis]. univesity of counterbury. xiang zeng. (2017). finite element analysis of square rc columns confined by different configurations of transverse reinforcement. the open civil engineering journal, 11: 292-302. 93 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper optimization of cutting parameters for free cutting brass (cuzn35pb3) using taguchi method kemal temam ebrahim1, moera gutu jiru1,  and abdisa sisay2 1department of mechanical design and manufacturing engineering, adama science and technology university, p. o. box 1888, adama, ethiopia 2department of mechanical engineering, bule hora university, p. o. box 144, oromia, ethiopia article info abstract article history: received 3 february 2020 received in revised form 29 april 2020 accepted 16 may 2020 the need of smooth surface finish produced during machining process plays a greater role to reduce wear of the part and corrosion protection. however, the cost of making good surface finish depends on selection of optimized parameters and use of precision machines. dry turning operation is very important for saving cost of cutting fluid, contribute to clean environment and good for safety of machinist. pure copper produces a long tubular or tangled chips which makes machining very difficult because chips are rolled on cutting tool causing tool wear. machining of high ductility work material like copper can create high frictional forces between chip and cutting tool. this creates high tool wear due to poor chip formation. in this work, cutting parameters like cutting speed, depth of cut and feed are optimized for dry turning process using taguchi method. the optimum turning parameters in this study was obtained at higher cutting speed, lower feed and higher depth of cut. the minimum surface roughness at optimum turning parameters was obtained as 1.63 µm. result of variance indicates the contribution of cutting speed, feed and depth of cut were 88.74%, 1.13% and 6.46% respectively. among which cutting speed was the most significant factor for improving surface roughness. keywords: machining turning surface roughness taguchi method 1. introduction machining is a material removal process where a cutting tool made of a harder material than the workpiece is used to remove materials in conventional machining process. it is not only performed for the overall forming of parts into their ultimate shapes, but also it is used to convert castings, forgings or preformed blocks of metal into desired shapes, with size and finish specified to fulfil design requirements (singh et al., 2014). operations that can be done on lathe machine are turning, facing, counter turning and tapering, boring and chamfering. turning operation is very important material  corresponding author, e-mail: jirata2010moti@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.189 removal process in modern industry. at least one fifth of all applications in metal cutting are covered by turning operation. it is used to reduce the diameter of the work piece, usually to a specified dimension and to produce a smooth finish on the metal (pedro et al., 2012; saraswat et al., 2014). machinability, generally, is defined in terms of surface finish, tool life, force and power requirements and chip control. the machinability of materials depends on their composition, properties, and microstructure. thus, proper selection and control of process variables http://www.ejssd.astu.edu/ mailto:jirata2010moti@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 94 are important (sahoo, 2013). optimization of machining processes is usually based on finding operating conditions, which minimize machining costs and maximize production rate. the three important process parameters in this study are depth of cut, feed and cutting speed. surface roughness of a turned work-piece is dependent on these process parameters. in addition, it also depends on the several other exogenous factors such as work piece material and tool material type. mechanical properties, quality and type of the machine tool used, auxiliary tooling, and lubricant used are also another parameter (shaw, 1991; chen, 2000; pedro et al., 2012; wang and cheung, 2012; singh et al., 2014; zhang et al., 2015; zhong et al., 2017). surface roughness remain the main indicator of machined component quality as it is related with surface quality. achieving high surface quality by machining is a big challenge for machining industries at with more productivities and less machining time. even rough surfaces wear more quickly and have high friction coefficient than smooth surfaces. as the surface roughness increases, quality of product goes on decreasing. therefore, it should bridge the gap between quality and productivity (ezugwu et al., 2005). dry machining has got attention due to reduced cost of cutting fluid and less effect on causing environmental pollution which is generated from using metal cutting fluids. the optimization of turning process parameter in dry turning of sae52100 steel by using carbide inserts was studied (borse, 2014). the result showed that cutting speed is the most dominant factors which affects surface roughness and followed by feed and depth of cut. at low and moderate speed, feed marks observed whereas at higher speed feed marks were absent. researchers have investigated the effect of cutting speed, feed and depth of cut on the surface roughness of machined product of mild steel by using taguchi method (saraswat et al., 2014). their result showed that the surface roughness was highly affected by feed and depth of cut has low significant effect on the surface roughness. the analysis also shows that the predicted values and calculated values are very close, that clearly indicates that the developed model can be used to predict the surface roughness in the turning operation of mild steel. the minimum average surface roughness obtained by saraswat et al. (2014) was 2.22 µm. dry turning process is very important since it contributes to clean environment and safety for operator. many scientists have suggested the optimization of dry turning process for different materials (masounave et al., 1997; thomas and beauchamp, 2003; diniz and de oliveira, 2004; filiz et al., 2007; imran et al., 2014). the main objective of using cutting fluids in machining operations is the reduction of temperature in the cutting region to increase tool life. however, the advantages offered by cutting fluids have been strongly debated because of their negative effects on the economic aspect, the environment and the health of workers using them. a trend to solve these problems is cutting without fluid, a method named dry cutting, which has been made possible due to technological innovations. the study focuses on the surface integrity and wear mechanisms associated with mechanical microdrilling of nickel-base superalloy (inconel 718) under dry and wet cutting conditions was investigated (masounave et al., 1997). the result showed that the tool wear can be attributed to high chip contact length, higher temperatures, high adhesion and diffusion in wet cutting in comparison to dry cutting. mechanical properties makes a great contribution to surface roughness formation in ultra-precision machining due to the “size effect” and for different isotropic materials, the machined surface roughness under the same cutting conditions is different (wang and cheung, 2012; zhang et al., 2015 ). the selection of appropriate tool materials depends not only on the material to be machined, but also on process parameters and the characteristics of the machine tool (davis et al., 2014; zhong et al., 2017). surface roughness is highly affected by cutting parameters like cutting speed, depth of cut and feed rate during turning process on conventional lathe machine. these parameters must be within the recommended range depending on the type of material to be machined, tool geometry and tool material (chen, 2000; hayajneh, 2007; zein and irfan, 2018). micro-cutting experiments of copper grating were carried out using the self-developed polycrystalline diamond (pcd) micro tools and the effect of depth of cut, feed per tooth and spindle speed on dimensional accuracy and burr formation was investigated (zhong, et al., 2017). investigation surface roughness and stress modeling by finite element on orthogonal cutting of copper were studied (thiele et al., 1990). in this study kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 95 finite element (fe) method was applied to predict the stress during orthogonal cutting by simulating the machining process. comparative study on optimization of surface roughness parameters in turning en1a steel on a cnc lathe with coolant and without coolant was studied by a researcher (selvaraj and chandramohan, 2010). their result shows that the best surface finish was occurred with coolant. the main aim of this work is to fill the gap on practical cutting parameter of dry machining of free cutting brass (cuzn35pb3) by taguchi optimization method. it is also to justify practical case of dry machining advantages in saving cost of cutting fluids and environmental clean production method. 2. experimental procedures the work piece materials used for this study was an alloy of copper, free cutting brass (cuzn35pb3) which, is used in the applications of bolts, nuts, gears, pinions and high-speed screw machine parts with dimension of 25 mm x 50 mm. free cutting brass (cuzn35pb3) of 500 mm in length and 25 mm in diameter was prepared. turning process at depth of cut 1 mm is used for removing any irregular parts on the surface for 450 mm of length. nine different experiments with dimension of 23 mm x 50 mm at 1.5, 2.5 and 3.5 mm of depth of cut would be operated for experimental study with different cutting parameters which is selected using orthogonal array. ceramic coated-carbide tool was used because of their chemical inertness, low thermal conductivity, resistance to high temperature, resistance to flank and crater wear since, ceramics are suitable coating materials for tools. the most commonly used ceramic coating is aluminum oxide (al2o3) (tilak, 2017). 2.1. design of experiment in the design of experiment (doe), taguchi method is used because it is a problem–solving tool which can improve the performance of the product, process design and system. the lathe machine with model of psg a141 and power of 7 kw with spindle speed range of 15rpm to 2000 rpm was used in this work. the cutting force was calculated from the net machine power and the corresponding cutting speed that is dividing net machine power. the average surface roughness for each sample was measured by surface contact profilometer in which the result was in micrometers. the properties and chemical composition of the workpiece material was given in table 1. table 1: properties and composition of free cutting brass (thiele jr et.al 1990) type and uns number nominal composition ultimate tensile strength (mpa) yield strength (mpa) elongation in 50 mm (%) hardness (hv) free-cutting brass (cuzn35pb3) 61.5% cu, 3.0% pb, 35.5% zn 340–470 125–310 53–18 52 figure 1: taguchi design procedure kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 96 table 2: list of parameters and their level cutting parameters parameters designation level 1 2 3 cutting speed (m/min) a 30 40 50 feed (mm/rev) b 0.3 0.5 0.7 depth of cut (mm) c 1.5 2.5 3.5 to observe the most influential process parameters in the turning process among them cutting speed, feed and depth of cut each at three levels were considered in the experiment as given in table 2. however, total number of experiments of the orthogonal array (oa) should be greater than or equal to the total dof required for the experiment. thus, l9 orthogonal array was selected to make the further experiments are shown in the table 3. this setup allows the testing of all three variables without having to run 27=33. nine different samples were manufactured with different parameters and at different levels. in the taguchi method the response variation was studied using signal-to-noise ratio and minimizing by optimizing the responses parameter. the smaller is the better s/n ratio used for these responses. 𝑆𝑁 = −10 𝑙𝑜𝑔 [ 1 𝑟 ∑ 𝑦𝑖 2 1 𝑖=1 ] (1) where, y is observation, r is total number of observation and yi is i th response. table 3: experimental layout using an l-9 orthogonal array ex. no cutting speed (m/min) feed (mm/rev) depth of cut (mm) 01 30 0.3 1.5 02 30 0.5 2.5 03 30 0.7 3.5 04 40 0.3 2.5 05 40 0.5 3.5 06 40 0.7 1.5 07 50 0.3 3.5 08 50 0.5 1.5 09 50 0.7 2.5 analysis of variance (anova) is the statistical technique used to find the influence of all control parameters. therefore, percentage contributions of each control factor was used to measure the corresponding effects on performance characteristics. the significance level of 5 %, i.e. for 95 % level of confidence was considered in this analysis. 3. results and discussion 3.1. the effect of cutting parameters on the surface roughness all nine experiments were conducted with different cutting parameters but at the same length of 50 mm. samples of free cutting brass material are given in figure 2. the diameter of the workpiece prepared for experimental work is 23 mm. turning process was conducted with 1.5, 2.5 and 3.5 mm depth of cut. sample number 1, 2 and 3 were operated by similar cutting speed of 30 m/min but, with different feeds (0.3, 0.5 and 0.7 respectively for sample 1, 2 and 3) and depth of cut (1.5, 2.5 and 3.5 respectively for sample 1, 2 and 3). by similar manner samples number 4, 5 and 6 were operated by similar cutting speed of 40 m/min but with different feed (0.3, 0.5 and 0.7, respectively) and depth of cuts (2.5, 3.5 and 1.5, respectively). the last three samples were also operated by similar cutting speed of 50 m/min, but with different feeds (0.3, 0.5 and 0.7, respectively) and depth of cuts (3.5, 1.5 and 2.5, respectively). figure 2: samples after turning process 3.2. optimization of cutting parameters taguchi's orthogonal arrays are highly fractional orthogonal designs. orthogonal array designs focus primarily on main effects. these designs are used to estimate main effects using only a few experimental runs. taguchi signal-to-noise ratios (s/n), which are log functions of desired output, serve as objective functions for optimization, help in data analysis and prediction of optimum results. in taguchi method, response variation is studied with the help of signal-tonoise (s/n) ratio. kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 97 table 4: experimental result for mean value of surface roughness 3.2.1. analysis of mean for surface roughness the average mean value of surface roughness for each factor i.e. cutting speed (a), feed (b) and depth of cut (c) were calculated using the design of experiments. table 4 presents the experimental results of surface roughness (ra) values for each specimen and their mean values which are measured by surface contact profilometer. in this study each surface roughness trial value is the average of three trial reading. table 5 shows that cutting speed has more effect on surface roughness since the delta value was 1.35 and ranking of 1. the factor with the least effect on the mean is feed (delta = 0.15, rank = 3). those parameter levels with better surface finish value of specimens that means a3b1c3 will be taken as a possible parameter combination for better values. the significant factors in the order increasing by affecting surface roughness is feed, depth of cut and cutting speed as shown in table 5. table 5: the response values of mean effect plot (smaller is better). figure 3: the effect of (a) feed and (b) depth of cut on surface roughness at cutting speed of 30 m/min with increasing feed from 0.3 mm/rev to 0.5 mm/rev, surface roughness increased from 3.27 µm to 3.50 µm and then decreased to 2.74 µm when feed increased to 0.7 mm/rev at cutting speed of 30 m/min as shown in figure 3(a). similarly, as depth of cut is increased from 1.5 mm to 2.5 mm the surface roughness was also increased but surface roughness decreased when depth of cut was increased to 3.5 mm at cutting exp. no. cutting speed (m/min) feed (mm/rev) depth of cut (mm) surface roughness (µm) avg. ra (µm) s/n ratios trial 1 trial 2 trial 3 1 30 0.3 1.5 3.5 3.47 2.83 3.27 -10.29 2 30 0.5 2.5 3.22 3.93 3.35 3.50 -10.88 3 30 0.7 3.5 3.29 2.81 2.12 2.74 -8.76 4 40 0.3 2.5 2.75 3.67 2.2 2.87 -9.16 5 40 0.5 3.5 3.15 2.7 2.85 2.90 -9.25 6 40 0.7 1.5 3.01 3.22 2.95 3.06 -9.71 7 50 0.3 3.5 1.58 1.97 1.34 1.63 -4.24 8 50 0.5 1.5 1.8 1.92 1.75 1.82 -5.2 9 50 0.7 2.5 1.9 2.19 1.93 2.01 -6.06 average performance mean value 2.64 -8.17 level cutting speed depth of cut feed symbol a b c 1 3.17 2.59 2.72 2 2.94 2.74 2.79 3 1.82 2.60 2.42 delta 1.35 0.15 0.37 rank 1 3 2 2.6 2.8 3 3.2 3.4 3.6 0.25 0.35 0.45 0.55 0.65 0.75 a v r. . su rf a c e r o u g h n e ss feed (mm/rev) (a) 2.6 2.8 3 3.2 3.4 3.6 1.25 2.25 3.25 4.25 a v r. . su rf a c e r o u g h n e ss depth of cut (mm) (b) kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 98 speed of 30 m/min as shown in figure 3(b). for given feed and depth of cut shown in figure 3(a, b), the optimum cutting parameters resulted in minimum surface roughness. with increasing the feed from 0.3 mm/rev to 0.7 mm/rev, surface roughness increased to 2.90 µm at constant cutting speed of 40 m/min as shown in figure 4(a). the surface roughness was increased with increasing depth of cut from 1.5 mm to 2.5 mm and then decreased when depth of cut was increased to 3.5 mm at cutting speed of 40 m/min as shown in figure 4(b). figure 4: the effect of feed (a) and depth of cut (b) on surface roughness at cutting speed of 40m/min. surface roughness was increased from 1.63 µm to 2.01µm with increasing feed from 0.3 mm/rev to 0.7 mm/rev at cutting speed of 50 m/min as shown in figure 5(a). the surface roughness was increased when the depth of cut was increased from 1.5 mm to 2.5 mm and then decreased with increasing depth of cut to 3.5 mm at cutting speed of 50 m/min as shown in figure 5(b). figure 6 shows that with increasing cutting speed from 30 m/min to 50 m/min the surface roughness also increases at both constant feed 0.3 mm/rev and 0.5 mm/rev. but at 0.7mm/rev feed the surface roughness was increased initially with increasing cutting speed from 30 m/min to 40 m/min and then decreased when cutting speed was increased to 50 m/min as shown in figure 6 (b). generally, the surface roughness increased with increasing feed and decreased with increasing depth of cut and cutting speed within the scope of this investigation. the reason for decreasing of surface roughness is to reduce wear, corrosion resistance and friction as well as to get the product with high quality. figure 5: the effect of (a) feed and (b) depth of cut on surface roughness at cutting speed of 50 m/min. figure 6: the effect of cutting speed on the surface roughness at 0.3 mm/rev feed, at 0.5 mm/rev and at 0.7 mm/rev. 1.5 2 2.5 3 3.5 4 25 30 35 40 45 50 55 a v r. s u rf a c e r o u g h n e ss cutting speed (m/min) 0.3mm/rev 0.5mm/rev 0.7mm/rev 2.85 2.9 2.95 3 3.05 3.1 0.25 0.45 0.65 0.85 a v r. . su rf a c e r o u g h n e ss feed (mm/rev) (a) 1.6 1.7 1.8 1.9 2 2.1 1.25 2.25 3.25 4.25 a v r. . su rf a c e r o u g h n e ss depth of cut (mm) (b) 1.5 1.6 1.7 1.8 1.9 2 2.1 0.25 0.35 0.45 0.55 0.65 0.75 a v r. . su rf a c e r o u g h n e ss feed (mm/rev) (a) 1.5 1.6 1.7 1.8 1.9 2 2.1 1.25 1.75 2.25 2.75 3.25 3.75a v r. . su rf a c e r o u g h n e ss depth of cut (mm) (b) kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 99 for predicting the optimum response, three factors of parameters are selected by small mean value. a3b1c3 is the optimum levels of parameters mean value for surface roughness value. to find out predicted value of the responses (surface roughness value) the following linear regression equation is used: 𝑦0𝑝𝑡 = 𝑚 + (𝑚𝐴3 − 𝑚) + (𝑚𝐵1 − 𝑚) + (𝑚𝐶3 − 𝑚) (2) where, m = average performance mean value for surface roughness, 𝑚𝐴3 = optimum level value for parameter a, 𝑚𝐵1= optimum level value for parameter b, 𝑚𝐶3= optimum level value for parameter c. 𝑦0𝑝𝑡 = 2.64 + (1.82 − 2.64) + (2.59 − 2.64) + (2.42 − 2.64) 𝑦0𝑝𝑡 = 1.55 (predict mean value for surface roughness value). 3.2.2. analysis of s/n ratios for surface roughness the taguchi method uses s/n ratio to measure the variations of the surface roughness value in experimental design. table 6 presents the calculations of s/n ratios for surface roughness value results using design of experiments. table 6: response table for signal to noise ratios smaller is better surface roughness response shown in table 6 shows that for signal to noise ratios of cutting speed weight percentage have the greatest effect (delta = 4.81, rank = 1). the factor with the least effect on the (s/n) ratio is feed (delta = 0.55, rank = 3). the optimal parameter combination on smaller is the better surface quality character is a3b1c3 are the possible parameter combinations for increasing the surface finish of the samples. the numerical value of the maximum point in each graph shows the best value of particular parameter at that level. they also indicate the optimum conditions in the range of the experimental conditions. since, s/n ratio used for this study is smaller is better and smallest s/n ratio was selected as it shown in the figure 6 (a), (b) and (c). that is at 50 m/min cutting speed, 0.3 mm/rev feed and depth of cut at 3.5 mm (a3b1c3) was selected. for predicting the optimum response approximately, three factors of parameters are selected by low s/n ratio value. a3b1c3 is the optimum levels of parameters s/n ratio value for surface roughness value. to find out predicted values of the response (surface roughness value), linear regression equation was used: 𝑦0𝑝𝑡 = 𝑚 + (𝑚𝐴3 − 𝑚) + (𝑚𝐵1 − 𝑚) + (𝑚𝐶3 − 𝑚) 𝑦0𝑝𝑡 = −8.17 + (−5.17 − (−8.17)) + (−7.90 − (−8.17)) + (−7.42 − (−8.17)) 𝑦0𝑝𝑡 = −4.15 (predict s/n value for surface roughness). 3.2.3. analysis of variance (anova) for surface roughness analysis of variance (anova) is used to identify the most significant factors which affects the surface roughness of the machined part. the result is reported in table 7. the percent contribution for each factor was also calculated. from table 7, it was clearly observed that cutting speed weight percentage (88.74%), feed (1.13%), depth of cut (6.46%) and the residual error (3.67%) had significant influence on surface roughness of free cutting brass specimens. therefore, cutting speed has high significant effect parameter on the surface roughness of free cutting brass in dry turning process by 88.74% of contribution. depth of cut has significant influence on the surface roughness by 6.46% contribution. but feed has the least significant influence on the surface roughness of free cutting brass during dry turning process. 3.2.4. confirmation test once the optimal combination of process parameters and their levels was obtained, the final step was to verify the predicted result against experimental result. if the optimal combination of parameters and their levels coincidently match with one of the experiments in the orthogonal array, then no confirmation test is required. by considering this, confirmation test was not required in this work, because the optimum combination of parameters and their levels (a3b1c3) have a correspondent level cutting speed feed depth of cut symbol a b c 1 -9.98 -7.90 -8.40 2 -9.37 -8.44 -8.70 3 -5.17 -8.18 -7.42 delta 4.81 0.55 1.29 rank 1 3 2 kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 100 table 7: analysis of variance for surface roughness value source dof sst sstr mse f p percent contribution significance (α=0.05) cutting speed 2 3.14 3.14 1.57 24.75 0.039 88.74% highly significant feed 2 0.04 0.04 0.02 0.33 0.754 1.13% less significant depth of cut 2 0.23 0.23 0.11 1.81 0.356 6.46% significant residual error 2 0.13 0.13 0.06 3.67% total 8 3.53 100% table 8: comparison between predicted and experimental confirmation to an experiment of the orthogonal array of the trail 7 condition of the experiment. the obtained optimal factor combination is one of the trial conditions (trial 7) of the experiment. thus, the minimum average surface roughness in this study was 1.63 µm as it is showed in table 4, which was at 50 m/min cutting speed, 0.3 mm/rev feed and 3.5 mm depth of cut. table 8 presents the confirmation experiment and predicted results comparison for surface roughness measurements. it can be seen from table 8, the difference between experimental result and the predicted results are very small. the values predicted by using taguchi approach is approximately near to the value which is experimentally obtained. this verify that, the experimental results of surface roughness are strongly correlated with the predicted results. 3.2.5. observation of chip morphology discontinuous chips were observed due to heterogeneous microstructure of the free cutting brass, in dry turning operation of this study. figure 8 shows the chips formed in dry turning process of free cutting brass for all nine different experiments. it was reported that, due to the presence of lead element in the free cutting brass alloy the chips produced were discontinuous type (chiappini, 2014). the maximum and minimum length of these chips were identified. the chips of all samples can be observed as discontinuous type of chips. but samples no. 7, 8 and 9 have chips with smallest size due to high cutting speed during the turning process and samples no. 1, 2 and 3 have discontinuous chips with long length because of low cutting speed during the process. but samples no. 4, 5 and 6 have chips with small and long in size since it was operated with moderate cutting speed. the longest chip was 1.6 mm long which is for sample no. 3 because of low cutting speed of 30 m/min and high depth of cut 3.5 mm. the smallest is approximately the size of powder which is in micrometers for sample no. 8 due to speed of 50 m/min and low depth of cut. at optimum value of cutting parameters the chips produced was discontinuous which is preferable for turning operation without any difficulties during the operation. the chips produced at optimum cutting parameters were shown in figure 7(c) which is for sample seven. figure 7: chip morphology (a) for experiment 1, 2 and 3 (b) for experiment 4, 5 and 6 (c) for experiment 7, 8 and 9. 4. conclusions the present research consists of experimental investigation on the dry turning process of free cutting brass with different turning parameters like cutting speed, feed and depth of cut to study their effects on the surface roughness of finished product. 1. optimization of the surface roughness was done using taguchi method. in turning of free cutting brass for minimum surface roughness, use of higher cutting speed (50 m/min), lower feed (0.3 mm/rev) and higher depth of cut (3.5 mm) were selected. a3b1c3 are optimized to get low surface response optimal parameter predicted value experimental value surface roughness (µm) a3b1c3 mean s/n mean s/n 1.55 -4.15 1.63 -4.24 kemal temam et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 101 roughness which is high surface finish of machined part. 2. the minimum average surface roughness during this study was 1.63 µm. the results of the anova indicate that the percentage contribution of cutting speed, feed and the depth of cut on the surface roughness were 88.74%, 1.13% and 6.46%, respectively. 3. from the percentage contribution of the anova, the cutting speed has highest significant effect on the surface roughness and feed has least significant. the possibility of dry machining for free cutting brass which save cost of machining and also contributes to green manufacturing was also a finding of this work. 4. this work has proved implementation of micromanufacturing using conventional machining process due to the fact that the surface finish obtained was in microns. reference borse, s.c. 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(2017). fabrication of pcd micro cutting tool and experimental investigation on machining of copper grating. the international journal of advanced manufacturing technology, 88(912): 2417-2427. 56 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu research paper ethiopian higher education and economic growth nexus chala amante abate department of economics, college of business and economics, salale university, p.o.box: 245 fitche, ethiopia article info abstract article history: received 18 may 2020 received in revised form 16 february 2021 accepted 22 february 2021 ethiopian government has paid great attention to higher education expansion and hence, it has been a national policy issue of the country. the study investigated the dynamic relationship between higher education and economic growth in ethiopia using annual data collected from 1981-2014. autoregressive distributive lag framework was used along with error correction term so as to investigate long run relationship between real gdp, enrollment in higher education, gross capital formation and labor. the result from bounds test confirmed the existence of strong long run relationship between variables. enrollment in higher education and gross capital formation has positive long run effect on real gdp. but, only enrollment in higher education has negative effect in the short run. the study utilized granger causality test in order to examine causal relationship between higher education and economic growth. according to the test result, a unidirectional causality running from higher education to economic growth was observed. the necessary diagnostic tests were applied in order to check reliability and acceptability of model outputs and they were found satisfactory. drawing on the finding it is recommended that government should continue expanding provision of higher education and in the meantime endeavor to improve quality of the provision. keywords: autoregressive distributive lag bound test error correction term ethiopia granger causality 1. introduction attainment of higher rate of economic growth is one of the prime aims of nations. the argument held over a long period of time was that physical capital matters more for economic growth. however, contemporary researches on the subject matter indicate the existence of other dimensions of capital like social capital and human capital as source of economic growth. according to rusli and hamid (2014) and devadas (2015), human capital is the key factor in economic growth attempt of a nation. it is the skills, knowledge and experience possessed by an individual (bergheim, 2005) and (pettinger, 2017). one of sources from which an individual obtains these important resources is educational institutions. therefore, educational institutions can play a significant role in economic progress of corresponding author, e-mail: chaliamante@gmail.com https://doi.org/10.20372/ejssdastu:v8.i2.2021.249 nations. this assertion is reflected in 2006 by the former united nations secretary general, kofi annan. he argued that the primary driver of africa’s development in 21st century will inevitably be universities. according to berhane (2000), skills and knowledge can be developed through attainment of formal educational system in response to which developing countries are expanding educational opportunities. ethiopia is not the exception where expansion (especially tertiary education) and reforms are at the heart of national policies. these re, education training policy (etp) in 1994, successive five year, education sector development programs (esdp) since 1998 and higher education proclamation in 2003 to feed demand of growing economy and in order to realize the vision of http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i2.2021.249 chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 57 joining medium income group by 2030 (teshome, 2004); (saint, 2004) and (yusuf and pilay, 2014). even though higher education in the country is not even a century old, as it was started in1950 (teshome, 1990), enrollment has increased at a higher rate (rayner and ashcroft, 2011). according to report from ministry of education (2003), from 1997/98 to 2002/03, it has increased by more than threefold (43,843 in 1997/98 to 147,954 in 2002/03). seven years latter (2009/10), enrollment in tertiary education has increased to 434,659, which is virtually three times higher. the figure further rose to 860,378 in 2016/17 which is about to double (moe, 2017). over the period elapsing between 2009 and 2013, nearly half of general government expenditure on education went on to finance tertiary education (unesco institute of statistics, 2019). in the same way, there is also observed expansion in tertiary education institution. looking at government universities alone, there are 44 universities in the country and direction was put forward to increase it to 50 in near feature. according to yirdaw (2016), there was no single private higher education in the country prior to 1991. but, about 76 private institutions emerged between 1992 and 2016. in nutshell, all these facts indicate that tertiary education has been given a due attention in the country. there are literatures that stress the different ways through which tertiary education can contribute to economic growth of a country. according to oketch et al (2014), these are increased productivity and income, increased capability and institutional improvements. according to the source, even though researches done during post-independence era advocating importance of higher education both for private and public faced fierce criticism by latter studies. endogenous growth theories since 1990’s have emerged with theoretical explanation for contribution of higher education to economic growth. they argued that highly skilled personnel are required for technology adaptation and transfer and at the same time increase efficiency and productivity of the economy (lucas, 1988). endogenous growth theories also stress non market private benefits like improved health and reduced family size as a components of capability approach to growth resulted from higher education (oketch et al., 2014). moreover, higher education results also in nonmarket social benefits like democratic institutions and political stability mugizi (2018) and wambua and mugendi (2019). according to world bank group (2017), higher education can reduce poverty and encourage shared property within the society. however, it is impossible to blindly recommend a certain country engage in expansion of higher education in order to bring about economic growth in light of the above arguments because there are empirical evidences that show absence of significant relationship or negative relationship between education and economic growth temple (1999); bils and klenow (2000); pritchett 2000; hadushek and wobmann, (2007); horii et al (2008); chaudhary et al. (2009); behrooznia et al (2016). the most frequently cited reason for such result to happen by studies including those given above is that poor quality sidelined with expansion of higher education. for that matter, researches conducted on higher education in ethiopia testify the existence of poor quality in ethiopian higher education system (saint, 2004); ayenachew (2015); (arega, 2016); shibru et al (2016); alemayehu and solomon (2017) and mulu (2017). there is a plethora of growth literatures in ethiopia, of which a great account and detailed study was done by weeks et al (2004). the study was aimed at figuring out source of growth in the country and found a pretty much importance of labor to growth. the physical capital (not human capital) included in the growth model employed by the study was found to be insignificant. the same topic was researched by ahmed and kenji (2016) where human capital was considered as an independent variable. in the study too, human capital (labor productivity) has no impact on gdp of the country. absence of relationship between gdp and human capital was also found in study by woubet (2006). another worth mentioning study on the subject is that conducted by engidaw and federici (2019). in this study, however, human capital is positive significant variable affecting economic growth both in the short run and long run. similar result was also obtained in the study by kidanemariam (2016). as to another different result, the negative relationship between human capital and economic growth was obtained by tefera (2017). the study included education expenditure and education enrollment as independent variables in the study which inevitably result in multicolliniarity problem. in spite of the need to investigate whether endogenous growth theory fits or the case of empirical results indicated above holds in the country, to the best chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 58 of knowledge we have, there are no prior studies undertaken in the country with particular focus on causal relationship between higher education and economic growth of ethiopia. moreover, owing to domestic literatures reviewed above, the relationship between human capital in general and economic growth is inconclusive. therefore, the objective of the current study is to find out whether there is a causal relationship between economic growth and higher education in ethiopia and also whether they move together in the long run. thus, the study tests two hypotheses. (1) there is long run relationship between higher education and economic growth of ethiopia. (2) there is no dynamic causality running from higher education to economic growth of ethiopia. 2. materials and methods to serve the purpose of current study, a time series data spanning from 1981 to 2014 was collected from available sources on four variables such as real gdp, enrollment in higher education, working age population and gross capital formation. real gdp is used to measure economic growth of the country. enrollment in higher education (number) is used to proxy higher education. enrollment instead of number of graduates is used because of data availability. over the period considered, few data values were missing but they are filled with multiple imputation technique. working age population is used to proxy labor and gross capital formation is used to proxy physical capital. the choice of the variables and the corresponding proxies used are supported by available literatures. real gdp, labor and enrollment in higher education were accessed from world bank indicator while gross capital formation was obtained from ethiopian ministry of financial development (mofed). both of these data sources are reliable from which many scholars utilize data. for the purpose of estimation and tests eviews version 9 was used. 2.1. model specification the theoretical model employed by this study is a neoclassical growth model developed by solow (1956) and extended by endogenous growth models romer (1989) and lucas (1988). according to the model, relying on coup douglas production function, the national income is the function of factors of productions like physical capital and labor as originally introduced and human capital as latter incorporated. keeping the former two inputs in place, in this study i use higher education enrollment instead of human capital variable. 𝑌 = 𝐴𝐻𝛾 𝐾𝛼 𝐿𝛽……………..………………. (1) where, 𝐴 is technological progress, 𝐾 physical capital, 𝐿 is labor and 𝐻 is human capital variable and 𝛾, 𝛼 and 𝛽 are parameters. following proxies for the variables indicated above, the above equation can be written as; 𝑌 = 𝐴𝐸𝐻𝐸𝛾 𝐺𝐶𝐹𝛼 𝐿𝑅𝛽……………………… (2) where, 𝑌 is real gdp, 𝐸𝐻𝐸 is enrollment in higher education, 𝐺𝐶𝐹 is gross capital formation, 𝐿𝑅 is labor force and the other symbols are defined above. taking natural log to both sides of the equation we get the following equation. 𝑛𝑌 = 𝑙𝑛𝐴 + 𝛾𝑙𝑛𝐸𝐻𝐸 + 𝛼𝑙𝑛𝐺𝐶𝐹 + 𝛽𝑙𝑛𝐿𝑅… (3) then the time series econometric model representation of the above equation is given below where, in addition to symbol defined above, t is time period and εi is the disturbance term. 𝑙𝑛𝑌𝑡 = 𝑙𝑛𝐴 + 𝛾𝑙𝑛𝐸𝐻𝐸𝑡 + 𝛼𝑙𝑛𝐺𝐶𝐹𝑡 + 𝛽𝑙𝑛𝐿𝑅𝑡 + 𝑖 (4) in case variables considered are integrated of different order but not integrated of order two (i(2)) and more, there are no best models than ardl (pesaran and shin, 1998). the model was originally developed by pesaran et al. (1996) and got popularity over other alternative models because of the following. firstly, it can be applied even though variables are integrated of different order, that is some are integrated of order zero and some are integrated of order one. secondly, it can be used for small sample size. thirdly, the use of it overcomes the problem of serial correlation (nkoro and uko, 2016). estimation of ardl usually involves three steps. firstly, unit root test should be applied in order to ascertain that none of the variables is i(2) or more. then co-integration test drawing on bound test should be applied to check for long run relationship. finally, causality should be analyzed. 2.2. unit root care should be taken when dealing with time series data in order to avoid a problem called spurious regression. spurious regression is a regression that leads to fallacious result as dependent variable is regressed over a set of explanatory variables lacking constant means and variance (guarati, 2003). when that happens, we say the variable has got unit root. in order to overcome this problem, we need to test data on the variables for unit root and once detected, take chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 59 appropriate measures and the most often used remedy is differencing. there are alternative techniques for testing unit root of which augmented dicky fuller test is the most common. for the purpose of current study, augmented dicky fuller (adf), which was developed by dichey and fuller (1979) and phillips perron test (pp) which was developed by phillips and perron (1988) are used. the novelty in these tests of unit root is that they take care of possible serial correlation among the residuals. while adf test takes care of serial correlation by adding lagged difference terms of the dependent variable, pp test do so by using nonparametric statistical methods (gujarati, 2002). the following equation gives adf test method. ∆𝑌𝑡 = 𝛽1 + 𝛽2𝑡 + 𝛿𝑌𝑡−1 + ∑ 𝛼𝑖 ∆𝑌𝑡−𝑖 + 𝑖 𝑚 𝑖=1 ….. (5) where, ∆ is difference operator, 𝑚 is the appropriate lag length and 𝑖 is a white noise disturbance term,𝑌, is a variable that is to be tested for unit root and 𝑡 is the time index. 2.3. co-integration once order of integration is tested, the next step in ardl estimation framework is test of co-integration. the current study employs bound test approach developed by pesaran et al. (2001) to examine the existence of long run association between the variables. to this end, the unrestricted vector error correction model (uvecm) up on which the test technique depends is specified below (equation 6, 7, 8 and 9). 2.4. granger causality granger causality test is the third step in ardl estimation framework. the test is applied when we have the evidence that all of our variables are co-integrated. furthermore, we should go for this test because cointegration test provide information about whether there is log run relationship but not direction of causality. the foundation for granger causality is the assumption that past values of certain variable can influence the future value of the other(s). as it is given in the following vector of equation if coefficients of lagged values of independent variables separately are significant, then we say our independent variable of interest granger causes the dependent variable; and we should proceed the test if we are about to argue vise-versa (granger, 1988). ∆𝑙𝑛𝐸𝐻𝐸𝑡 = 𝛼0 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐸𝐻𝐸𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝑌𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐺𝐶𝐹𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐿𝑅𝑡−𝑖 𝑝 𝑖=1 + 𝛼1𝑙𝑛𝐸𝐻𝐸𝑡−1 + 𝛼1𝑙𝑛𝑌𝑡−1 + 𝛼1𝑙𝑛𝐺𝐶𝐹𝑡−1 + 𝛼1𝑙𝑛𝐿𝑅𝑡−1 + 1𝑡 … … … … … … … … … … … … … … … … … … … … . (6) ∆𝑙𝑛𝐺𝐶𝐹𝑡 = 𝛼0 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐺𝐶𝐹𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐸𝐻𝐸𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝑌𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐿𝑅𝑡−𝑖 𝑝 𝑖=1 + 𝛼1𝑙𝑛𝐺𝐶𝐹𝑡−1 + 𝛼1𝑙𝑛𝐸𝐻𝐸𝑡−1 + 𝛼1𝑙𝑛𝑌𝑡−1 + 𝛼1𝑙𝑛𝐿𝑅𝑡−1 + 1𝑡 … … … … … … … … … … … … … … … … . . … … … . . (7) ∆𝑙𝑛𝐿𝑅𝑡 = 𝛼0 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐿𝑅𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐸𝐻𝐸𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐺𝐶𝐹𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝑌𝑡−𝑖 𝑝 𝑖=1 + 𝛼1𝑙𝑛𝐿𝑅𝑡−1 + 𝛼1𝑙𝑛𝐸𝐻𝐸𝑡−1 + 𝛼1𝑙𝑛𝐺𝐶𝐹𝑡−1 + 𝛼1𝑙𝑛𝑌𝑡−1 + 1𝑡 … … … … … … … … … … … … … … … … … … . . . . (8) ∆𝑙𝑛𝑌𝑡 = 𝛼0 + ∑ 𝛼𝑖 ∆𝑙𝑛𝑌𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐸𝐻𝐸𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐺𝐶𝐹𝑡−𝑖 𝑝 𝑖=1 + ∑ 𝛼𝑖 ∆𝑙𝑛𝐿𝑅𝑡−𝑖 𝑝 𝑖=1 + 𝛼1𝑙𝑛𝑌𝑡−1 + 𝛼1𝑙𝑛𝐸𝐻𝐸𝑡−1 + 𝛼1𝑙𝑛𝐺𝐶𝐹𝑡−1 + 𝛼1𝑙𝑛𝐿𝑅𝑡−1 + 1𝑡 … … … … … … … . . … … … … … … … … … … … … . . … … … . . … … (9) where, 𝑝 is the maximum lag length suggested by information criteria and they are not necessarily the same for all of the variables and other symbols are as defined before. [ ∆𝑙𝑛𝐸𝐻𝐸𝑡 ∆𝑙𝑛𝐺𝐶𝐹𝑡 ∆𝑙𝑛𝐿𝑅𝑡 ∆𝑙𝑛𝑌𝑡 ] = [ 𝜃1 𝜃2 𝜃3 𝜃4 ] + ∑ [ 𝜑11𝜑12𝜑13𝜑14 𝜑21𝜑22𝜑23𝜑24 𝜑31𝜑32𝜑33𝜑34 𝜑41𝜑42𝜑43𝜑44 ] 𝑝 𝑖=1 [ ∆𝑙𝑛𝐸𝐻𝐸𝑡−𝑖 ∆𝑙𝑛𝐺𝐶𝐹𝑡−𝑖 ∆𝑙𝑛𝐿𝑅𝑡−𝑖 ∆𝑙𝑛𝑌−𝑖𝑡 ] + [ 1 2 3 4 ] [𝐸𝐶𝑇𝑡−1] + [ 𝜇1𝑡 𝜇2𝑡 𝜇3𝑡 𝜇4𝑡 ] … … … … … … … … … … … (10) where, 𝐸𝐶𝑇𝑡−1 is the lagged error correction term derived from the long run relationship, 𝜇1𝑡 , 𝜇2𝑡 , 𝜇3𝑡 , and 𝜇4𝑡 are serially uncorrelated disturbance terms. chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 60 3. results and discussion 3.1. unit root test as it can be seen from table 1, the two unit root test techniques shows that all variables are not stationary at level but when converted in to first difference, all of them are stationary. so, our variables are integrated of order one (i(1)). thus the ardl model is estimated with i(1). the first deference of higher education and labor are checked at intercept and also, for the former, lag length 3 is used in adf case. 3.2. co-integration test because the result of unit root test given in table 1 shows none of variables included in the model are not integrated of order 2. it is possible to run ardl model because of its aforementioned merits. however, it needs to select optimal lag length before running the model. for that matter, there are five selection criteria that can guide us to select optimal lag length. as it is provided in table 2, three of such selection criteria suggest lag length three. with any maximum lag length imputed, eviews automatically selects appropriate lag order for each variable. accordingly, as the result is given in figure 1, the stated statistical software has selected an ardl model with specification (2, 3, 1, 0) based on akakai information criteria (aic). this information criterion is used because it is widely used criteria in ardl estimation. using the lag selection criteria, co-integration test result is given in table 3. the name of the test is known as bounds test in ardl framework. the test provides f-statistics along with upper bound and lower bound critical values at 1%, 2.5%, 5% and 10%. according to the test, three cases should be considered so as to accept or reject the null hypothesis which estates ‘no long run relationship exists’. the first case is where f-statistic is less than lower bound critical value and if this result happens the null hypothesis should be accepted. the second case is where the f-statistics is above the upper critical bounds and in this situation the null hypothesis should be rejected. as to another possibility, if the fstatistics found in between the lower and upper bound table 1: unit root test augmented dicky fuller test phillip perron test variable level first difference level first difference test statistics critical value test statistics critical value test statistics critical value test statistics critical value lnrgdp -0.442 -3.552 -3.796 -3.754 0.1005 -4.262 -5.824 -4.103 lnehe -1.588 -3.557 -3.439 -2.957 -1.317 -3.552 -3.460 -2.957 lngcf -2.045 -3.552 -7.736 -3.557 -1.940 -3.552 -14.12 -3.557 lnlr -2.206 -3.587 -3.007 -2.957 -1.910 -3.552 -3.021 -2.957 source: borld bank indicator and mofed table 2: lags selection criteria lag logl lr fpe aic sc hq 0 19.52589 na 4.32e-06 -1.00167 -0.81664 -0.941355 1 248.6317 384.3066 4.67e-12 -14.7504 -13.82528* -14.44886 2 273.2729 34.97461* 2.83e-12 -15.3079 -13.6427 -14.76509 3 293.3795 23.34954 2.53e-12* -15.57287* -13.1675 -14.78877* source: borld bank indicator and mofed.* indicates lag order selected by information criteria table 3: co-integration test (pesaran et al., 2001)) source: borld bank indicator and mofed test statistic value k f-statistic 11.79662 3 critical value bounds significance i0 bound i1 bound 10% 2.37 3.2 5% 2.79 3.67 2.50% 3.15 4.08 1% 3.65 4.66 chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 61 critical values, the test result is inconclusive. in this study, as it is given in table 3, the null hypothesis should be rejected meaning that the variables included in the model move together in the long run. on the other hand, variables included in the model are co-integrated which indicates the variables are necessary for one another. 3.3. the long run ardl model as it is given in table 4, higher education (also similarly obtained by gyimah-brempong (2006), becherair (2014) and nohak and dahal (2016)) and gross capital formation have positive significant effect on economic growth at 1%. from the regression result, coefficient of log of enrollment in higher education indicates as the number of enrollment in higher education increased by 10%, gdp increases by 2.45%, all relevant explanatory variables being unchanged. the result further indicates that a 10% increase in gross capital formation has an effect of increasing gdp by about 4.39%, other things remaining constant. implication of this result is that the sustained increased enrollment of higher education in the country is contributing to economic growth positively which might be due to the higher education in the country is boosting human capital and this result is supported by existing theory (endogenous growth theory). table 4: estimated long run coefficients using the ardl (2,3,1,0) long run model variable coefficient std. error tstatistic prob. lnehe 0.245*** 0.053 4.55 0.0002 lngcf 0.429*** 0.082 5.23 0.0000 lnlf -0.210 0.169 -1.24 0.2271 c 13.759 2.670 5.15 0.0000 source: world bank indicator and mofed 3.4. the short run model as the result is depicted in table 5, only higher education significantly affect economic growth over the period considered for this study. however, the sign of the variable is in this model is opposite to its sign in the long run model. in other words, enrollment in higher education affects economic growth positively in the long run and negatively in the short run. as the result clearly indicates, a 10% increase in the number of students enrolled in higher education in the short run decreases the real gross domestic income by about 2%. this could be engagement in illegal activities as argued by prichett (2001) or labor market problem (mismatch between skill and job) as argued by tefera (2017). table 5: vector error correction model and the short run dynamic equation variable coefficient std. error tstatistic prob. d(lnrgdp(-1)) 0.175 0.138 1.26 0.2201 d(lnehe) 0.046 0.072 0.63 0.5341 d(lnehe(-1)) 0.210 0.115 1.82 0.082 d(lnehe(-2)) -0.208** 0.074 -2.81 0.0104 d(lngcf) 0.048 0.040 1.20 0.2406 d(lnlf) -0.112 0.093 -1.20 0.2435 cointeq(-1) -0.534*** 0.095 -5.58 0.0000 source: world bank indicator and mofed concerning by the error correction model it should be negative in sign, between zero and one in absolute term and statistically significant. accordingly, all these requirements are met in the model and the error correction term is -0.5344 which is statistically significant at 1% significance level. the implication is that about 53% of disequilibrium occurred in previous year is corrected in current year. or simply, the speed of adjustment towards the long run equilibrium is about 53%. 3.5. diagnostic checking as test result is depicted in table 6, the model estimated is free from serial correlation of residuals and also are homoscedastic and have normal distribution. in addition, the model is well specified as guaranteed by ramsey reset test. the fitted model is also stable as it is confirmed by cusum and cusumq (result is given in figure 1). in cusum and cusumq test, so long as the fitted line lies within 5% critical values, the fitted model is said to be stable. table 6: diagnostic checking diagnostic test test tecknique applied fstatistics p-value normality of residuals jarque-bera 0.71 0.7 serial cirrelation breusch-godfrey serial correlation lm test: 0.56 0.57 heteroscedasticity breusch-pagan-godfrey 0.82 0.6 functional form ramsey reset test 0.007 0.92 source: world bank indicator and mofed chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 62 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 94 96 98 00 02 04 06 08 10 12 14 cusum of squares 5% significance -15 -10 -5 0 5 10 15 94 96 98 00 02 04 06 08 10 12 14 cusum 5% significance figure 1: test for model fit table 7: granger causality test null hypothesis: obs f-statistic prob. lnehe does not granger cause lnrgdp 31 3.50358 0.0308 lnrgdp does not granger cause lnehe 1.14430 0.3513 lngcf does not granger cause lnrgdp 31 9.51563 0.0003 lnrgdp does not granger cause lngcf 5.52528 0.0050 lnlf does not granger cause lnrgdp 31 1.25629 0.3116 lnrgdp does not granger cause lnlf 1.56488 0.2238 lngcf does not granger cause lnehe 31 1.77094 0.1796 lnehe does not granger cause lngcf 2.72766 0.0663 lnlf does not granger cause lnehe 31 1.95497 0.1477 lnehe does not granger cause lnlf 4.95731 0.0081 lnlf does not granger cause lngcf 31 2.73733 0.0657 lngcf does not granger cause lnlf 0.74105 0.5380 3.6. granger causality test the result of granger causality test is reported in table 7 above. the null hypothesis of the test is that lagged values of the dependent variable do not explain variation in the dependent variable. therefore, if probability value is greater than 0.05, we cannot reject the null hypothesis and conclude that there is no causality between variables considered. on the other hand if the probability value is less than 0.05, we cannot accept the null hypothesis and conclude that there is causality (granger, 1988). as it is indicated in table 6, there is a unidirectional causality running from higher education to economic growth (not vice versa). stated in other words, ethiopian economy is, in part, higher education driven and not growth stimulated higher education and both variables not feeding each other. this result rejects our prior hypothesis which estates there is no dynamic causality between higher education and economic growth. this result is in line with that of mariana (2015) and dudzevičiūtė and šimelytė (2018), but contradict with findings by chaudhary et al. (2009) and wambua and mugendi (2019). granger causality test also shows the existence of bidirectional causality between gross capital formation and real gdp. this implies that the two variables feed each other. to put it in other words, any measure taken with regards to capital formation in the country has bearings on economic growth of the country and vice versa. therefore, neither bidirectional causality nor is the direction of causality from economic growth to higher education. 4. conclusion and recommendations 4.1. conclusion ethiopian government has paid great attention to higher education expansion and hence, it has been a national policy issue of the country. while doing this, expectation from the sector on the part of the government is that it will help achievement of development dream of the country. however, some empirical evidences from across the world assert nonexistence of causal relationship between higher education and economic growth. if the same holds for chala amante ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 63 ethiopia, it means that government’s investment on higher education expansion is simply wastage and it ought to be diverted to other productive investments instead. thus, the aim of the current study was to investigate causal relationship between higher education and economic growth. to this end, time series data from 1981 to 2014 was collected on four variables such as real gdp, enrollment in higher education, gross capital formation, and labor. appropriate methodological procedures in light of available literatures were applied to analysis of the data. accordingly, estimation of ardl model was justified based on unit root test results and superiority of the model over other competing models. a bounds test approach associated with ardl was run to investigate long run relationship between real gdp, enrollment in higher education, gross capital formation and labor force; and from the test result, the followings were deduced: ‐ it was observed that there is a long run association ship between real gdp, enrollment in higher education, gross capital formation, and labor in ethiopia ‐ enrollment in higher education and gross capital formation positively affected economic growth of ethiopia in the long run ‐ enrollment in higher education negatively affected economic growth of ethiopia in the short run ‐ higher education causes economic growth, but not the reverse, in ethiopia ‐ gross capital formation and economic growth in ethiopia reinforce each other. 4.2. recommendations based on the output of the study, therefore, the author recommends the followings: ‐ government should continue energetic effort of providing higher education. while expanding higher education, however, emphasis should be given to quality because the negative effect of higher education in the short run could be attributed by poor quality of its provision. ‐ considerable investment in physical capital should be undertaken by the government and all necessary incentives should be given to private firms in order to induce them to engage in investment activities acknowledgments the author has a heartfelt gratitude to all sources of data. reference ahmed, k.y. and kenji, y. 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(2017). the impact of human capital on economic growth in ethiopia. master’s thesis, st. mary’s university. teshome yizengaw .(2004). the status and challenges of ethiopian higher education system and its contribution to development. the ethiopian journal of higher education, 1(1): 1-19 unesco. (2019). enrolment numbers and gross enrolment ratio at tertiary level by country and gender. unesco institute for statistics. weeks, j., alemayehu geda, daniel zerfu, & dawit weldyesus. (2004). source of growth in ethiopia. school of oriental andafrican studies, university of london. wambua, l.n. and mugendi, c. (2019). higher education expenditure and economic growth in kenya. the strategic journal of business & change management, 6(3): 112131 woubet kifle. (2006). human capital and economic growth in ethiopia. master’s thesis, addis ababa university. world bank (2014), world development indicators. the data is available on internet at http://data.worldbank.org/country/ ethiopia world bank group (2017). higher education for development an evaluation of the world bank group’s support. washington, dc 1818 h street nw. http://dx.doi.org/10.14207/ejsd.2018.v7n2p14 http://dx.doi.org/10.1080/00220380600576490 http://dx.doi.org/10.13189/ujer.2017.050408 http://r4d.dfid.gov.uk/ https://www.jstor.org/stable/24486295 http://data.worldbank.org/country/ 29 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper the role of parents in school management in private and government secondary schools in adama town wosene alemu demissie1, alemu disassa mulleta1,  , zebene gelagile2 1school of humanities and social science, adama science and technology university, p. o. box 1888, adama, ethiopia 2arsi university, p. o. box 193, asella, ethiopia article info abstract article history: received 3 february 2020 received in revised form 4 april 2020 accepted 6 may 2020 the major purpose of this study was to investigate the status of parental involvement in school management. to this end, a descriptive survey research design has been used to collect relevant data from 35 representatives of parents and 40 directors/vice directors in five government and seven private secondary schools in adama city administration using questionnaire, focus group discussion, and key informant interview. the quantitative data were analyzed using descriptive and inferential statistics while the qualitative data were analyzed thematically. results of the study reveal that both parents and directors seem to have positive attitude towards parental involvement in school management, yet the actual practice on the ground is not satisfactory. parents’ involvement is limited to raising and supervising the utilization of school fund and fulfilling school infrastructure. they have minimal involvement in planning school activities, supervising teachers, providing of pedagogical support, and recruiting students due to barriers such as time constraint, lack of initiative, lack of awareness on how to contribute, and absence of incentives for parents. although there are some differences in their mean values, statistically significant differences between private school and government school parents with regards to their involvement in school management were observed only on two domains: raising fund and managing students’ discipline. hence, working closely with community based association, raising parents’ awareness through trainings, and providing incentives have been recommended. keywords: school management parental involvement adama town 1. introduction 1.1. rationales for parental involvement in school management the idea of involving parents in school management has emerged based on two assumptions: their contribution in implementing decentralized school management system and their major role in child education. scholars affirm that involving parents or the community is one way of decentralizing and democratizing the educational management system of a country (mncube, 2009;  corresponding author, e-mail: alemu.disasa@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.196 naidoo, 2005; chapman et al., 2002). according to chapman et al. (2002), because of their proximity to their children’s school, parents are more likely to make timely and pertinent decisions that can address the concern of schools. dunne et al. (2007) also state that parents often make school related decisions with better sense of ownership and commitment. parents can also monitor the quality of education offered in their children’s school by ensuring proper utilization of school resources and solving problems http://www.ejssd.astu.edu/ mailto:alemu.disasa@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 30 related to educational inputs (duma et al., 2011; swiftmorgan, 2006; carnie, 2003; bray, 2000; williams, 1997). they can contribute to academic achievement of students by minimizing students’ dropout and disciplinary problems (ji & koblinsky, 2009; clase, kok & van der merwe, 2007; marschall, 2006; epstein, 2001). parents can also get involved in the development of better curriculum and teaching materials for schools (glanz, 2006). the extent and the domains of parents’ involvement may vary from place to place. some scholars agree up on six major domains of parental involvement in school management: infrastructure and maintenance, management and administration, teacher support and supervision, pedagogy and classroom support, student discipline, and student recruitment (swift-morgan, 2006; muskin, 2001). watt (2001) on his part categorizes domains of community support for schools into two as “monetary” and “non-monetary forms”. activities which involve fees, fundraising, and levies for supplementing teachers’ salary and maintaining of classrooms are categorized as “monetary support” while other activities which range from participating in school meetings up to making decisions which influence school performance are grouped under “non-monetary” forms of participation. parents can get involved in the school management through their representatives such as parent teacher association (pta) and other forms of organizations (epstein, 2001). they can also serve as members of school board (bray, 2000) and as members of cluster or village education committee which oversees several schools within a village (obsaa, 2010). as an academic institution, both private and government schools may follow similar procedures in discharging their responsibilities. however, there could be some variations between the two with regards to involving parents in the school management mainly due to differences in their organizational structure. in the case of government schools, zone and regional education bureau hold the highest level of accountability, whereas in private schools the ultimate decision making power is usually entrusted to elected school boards and/or elected officials (guernsey, 2003). among the major responsibilities and powers of school boards in private schools are developing policy and strategy, giving ultimate decisions on issues related to salary and employment, and supervising resource utilization. parental involvement is ensured in private schools through their representatives in the school board. parents often comprise of up to seventy percent of the private school board members (guernsey, 2003). this indicates additional roles that parents are expected to play in managing their children’s school. in general, parents’ involvement is crucial in the management of both government and private schools, yet there are some barriers to such practices of parents. 1.2. barriers to parents’ involvement in school management despite its aforementioned benefits, previous studies reveal several barriers to parental involvement in school management. among the barriers, economic conditions and educational status of parents, inconvenient political and institutional arrangements, and socio-cultural conditions are the major ones (ramadikela, 2012; adam, 2005; shaffer, 1994). according to these scholars, when the economic status of parents is low, their participation in the school management becomes minimal because these parents often engage in hard works for longer hours to curb their financial shortage. similarly, in a context where parents lack the necessary skill or educational capacity to carry out the roles they are supposed to play, involving them in the school management could be difficult (mncube, 2009). the attitude of parents also plays a big role in this regard. although most parents like to involve in the management of schools, some prefer to stay away from such practice because they “feel that they are not welcomed at the school building or by the teacher of their children” (murphy, 2002, p.40). some parents also consider such involvement as interference to teachers business which they have no control over (mncube, 2009; murphy, 2002). teachers’ negative attitude towards parents’ involvement in school governance, their lack of confidence in dealing with parents’ demand, and their lack of knowledge on how to involve parents are also among the major barriers to parental involvement in school management (ramadikela, 2012; baum & swick, 2007; cullingford & morrison, 1999). although they have the responsibility to take the lead in encouraging parents (griffith, 2001), some principals also consider parental involvement in the school wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 31 management as violation of their professionalism (duma, 2009; mncube, 2009). with regards to this, constantino (2007, p.58) claims that, “when cultivating family engagement to bring about enhanced student learning, perhaps the most important element is the principal’s belief in it”. lack of clear national policy for parental involvement in school management is also taken as a good excuse by educators to refrain from involving parents in the school system. in relation to this, colombo (2006) states that schools need to have a clear policy on how to involve parents in such a way that both sides taste clear benefits of the collaboration. when the reward that they get is less than the cost of supporting a school, parents are less interested to participate in the school management (watt, 2001). language and culture are also believed to be common barriers to parental involvement in school management (bridgemohan et al., 2005). scholars assert that failure to involve parents in the school management can lead to poor school performance or academic achievement, bad class attendance, poor students’ discipline (rogers, 2003), increased attrition rate and dropout rate (colombo, 2006). hence, considering the contributions that parents could make in improving school performance and academic achievement of their children, scholars suggest that schools and the government need to design a policy which facilitates such involvement. schools also need to work on empowering parents so that they can contribute effectively in the school management (colombo, 2006). griffith (2001) emphasizes that ensuring parental involvement in the school management must be among the key roles of principal. 1.3. parents’ involvement in school governance in ethiopia though the practice of involving parents in school management has long history in developed countries, such practice has been given special emphasis in developing countries following the dakar framework for action in senegal in the year 2000 (bray, 2000). cognizant of its benefits, the government of ethiopia has also designed and implemented a decentralized education policy that encourages community involvement in school management (fdre, 1994). school improvement program (sip), which involves head teacher, assistant head teacher, parents, representatives of local community, and students in the school management, has been introduced in ethiopia (moe, 1998). by doing so, the government has achieved significant success in improving access to education and creating sense of belongingness among communities (obsaa, 2010). however, local studies so far conducted in the area reveal some gap with regards to parental involvement in the school management in ethiopia. according to obsaa (2010), although community participation in the school management has helped in improving access, bringing equity in education and creating sense of belongingness among community, the attempts made by the ethiopian government to decentralize educational management through community participation is not free from challenges. workineh (2012) also found out that even though community and parents are playing significant role in the school management by making material and financial contributions, recruiting contract teachers and guards, building new classrooms, their awareness and level of participation in school affairs still needs improvement. the two local studies by obsaa (2010) and workinek (2012) reveal the situation in rural ethiopia focusing only on government schools. they did not investigate the situation in towns by comparing private schools and government schools. however, as indicated elsewhere in the preceding sections, parental involvement in school management may vary based on the socioeconomic background and literacy status of parents. in the context of ethiopia, most often, parents who send their children to private schools are in a better economic status or may also have better educational background than those parents who send their children to government schools. therefore, the level of involvement of the two parents in the management of their children’s school may vary. however, there seems to be no research which clearly shows the disparity in the level and types of parental involvement in school management in our country in general and in the context of the current study in particular. shibeshi (2009) also claims that research in the field of community participation in education is scant in ethiopia. thus, the current study aims at identifying the differences in the type and extent of parental involvement in school management in the government wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 32 and private secondary schools in adama city administration. such comparative study may help to see what the situation looks like in both types of schools and facilitate the sharing of good experiences. to this end, the researchers have tried to answer the following research questions:  what is the attitude of parents and directors towards the involvement of parents in the school management?  what are the actual practices of parents in the school management in the government and in the private secondary schools in adama city administration?  what are the major barriers to parents’ involvement in the school management?  are there significant differences between government secondary schools and private secondary schools in involving parents in the school management? 2. materials and methods 2.1. research design in this study, a descriptive survey research design with mixed approaches to data gathering and analysis has been employed. this research design has been selected because it is appropriate to answer research questions of the current study which give emphasis to describing the existing practices. 2.2. sample and sampling techniques the population of the study was drawn from secondary schools in adama city administration. by the time this study was conducted (feb, 2017), there were five government and seven private secondary schools in the city and all of them were used as data sites. out of 48 representatives of parents serving as members of parent-teachers association (pta), forty parents were selected using availability sampling while all 28 directors/ vice directors were selected as data sources. 2.3. method of data collection survey questionnaire, key informant interview, and focus group discussion (fgd) were used as major instruments of data collection. a five-point likert scale with responses ranging from “5= strongly agree” to “1=strongly disagree” was used to collect data from the directors and the parents. the items in the questionnaire cover demographic information of the respondents, attitude of the respondents towards the involvement of parents in school management, level of parental involvement, and barriers to parental involvement in school management. the questionnaire had been checked by two experts before it was pilot tested in one secondary school. based on the comments of the experts, and the outcome of the pilot test, some items were rephrased while others were omitted. only items with the average cronbach's alpha value of (r>72 for attitude, r>70 for practice and r>78 for hindering factors) were considered for the final study. besides, the english version of the parents’ questionnaire was translated back and forth into amharic to avoid potential misunderstanding. out of 81 questionnaires distributed to the target samples, 75 (92.6%) were properly filled and returned. the key informant interview (kii) was held with four directors: two from government schools and the other two from private schools. the schools were selected purposively because of their proximity and the presence of insider’s support. in order to help the interviewee focus on important issues, the researcher used interview guide. the fgd was held with selected representatives of parents or pta members in four of the selected schools: two in private and two in government schools. a total of fourteen participants were included in the fgd based on their willingness. all fgds were held outside school compound to minimize potential social desirability bias. 2.4. method of data analysis the quantitative data were fed into spss version 20 and analyzed using descriptive and inferential statistics, while the qualitative data were transcribed and analyzed thematically. extracts from the transcript have been quoted to illustrate the analysis. the analysis was done in an integrated approach using the quantitative data as major frame. to protect the privacy of the participants, anonymity of the sample schools and the participants has been maintained by refraining from mentioning names. 3. results and discussion 3.1. demographic information majority of the parents (60%) and the directors (82.5%) who served as data source are male. this indicates the fact that gender equity is not yet given wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 33 enough attention in the school management especially in the assignment of directors. nearly half of the parents (45%) who were involved in the study had educational qualification which ranges from diploma up to master’s degree. some percentage of the parents (22.9%) has also completed their secondary level education. majority of the directors (90%) were first degree and second degree holders. these results show that both parents and directors who took part in the current study have good educational background to deal with school management issues. more than half of the parents (54.2%) have served in the current school for more than four years. in contrast to this, the majority of the directors (75%) have served in the current school for less than four years. however, since most of the respondents had stayed in their respective schools for at least two years, the data that they provided for the current study is reliable from experience point of view. the percentage of respondents from private school (57.1%) is more than that of government school (42.9%). considering the numerical difference of the two types of schools in the town, the representation is appropriate enough to elicit relevant information. 3.2. attitude towards parental involvement in school management the attitude of directors and parents towards parental involvement in school management may affect the parents’ contribution in this regard. as it has been discussed elsewhere in the preceding sections, some directors consider parental involvement in school governance as violation of their professionalism (duma, 2009; mncube, 2009). in the current study, eleven items were included in the survey questionnaire to elicit information on the attitude of the respondents toward parental involvement in school management. as indicated in table 1, the mean scores on most of the items show that both the parents and the directors have positive attitude towards parental involvement in school management. for example, the mean value on item 1 for parents (m=3.9, sd=0.95) and for the directors (m= 4.1, sd=0.67) indicate that both parties agree on the importance of parental involvement in school management. the mean scores of both parties on item 3 also indicate that the two sides believe that parents can play significant role in creating healthy teaching environment. the mean value of item 2 and item 5 also reinforces this result. the fgds and kiis results also support the above findings. the participants strongly believe that parents can play significant roles especially in the proper management of school grant and fulfilling infrastructure. the target parents from both government and private schools reported that schools often invite them to comment on their annual plans. for instance, an fgd participant from a private school stated, “it is very good. schools have good willingness to involve us. every member of the parents committee freely expresses his feeling. the school presents its plan. we openly discuss on it” (parent, private school, april 7, 2017). similarly, a discussant from government school stated “in order to improve parental involvement, they send us invitation letter every three months. we go there and give our opinions on what they present” (parent, government school, april 7, 2017). table 1: respondents belief on the importance of parental involvement in school management n.b: bold texts in parenthesis ( ) shows how the same item is phrased in the directors’ questionnaire. sn items parents directors n m sd n m sd 1 i believe parents can play significant role in school management 35 3.91 0.95 40 4.10 0.67 2 the involvement of parents is not that much important in the management of schools * 35 1.74 0.82 39 1.56 0.88 3 parents’ involvement in school management can have significant role in creating healthy teaching environment. 34 4.21 0.65 38 3.82 0.80 4 as parents’ representative, (i feel) i am (parents are) playing significant role in the management of the school i have been assigned to. 35 4.40 0.91 40 4.28 0.72 5 parents should be given better mandates in the school management 35 4.34 0.59 40 4.00 0.75 wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 34 as can be seen from the preceding two excerpts, school directors seem to have good attitude towards parental involvement in the school management. the discussants expressed the freedom that parents have in commenting on the plan of schools. asked about what may happen if parents are not involved in the school management, one of the parents stated: if there is no participation of parents, the school [directors] will develop the sense of selfishness. they start to work for personal gain, to fill their pocket. i feel they will leave nothing for the next generation (parent from government school, april 3, 2017). this excerpt could be taken as an evidence for parents’ awareness on the importance of their involvement in the school management. it also indicates parents’ worry on the possible power abuse by directors unless parents are involved in the management of schools. the directors from both government and private schools also support the idea stated by the parents. as can be seen from the following excerpt, the directors reported that without the involvement of parents, schools hardly achieve their goals. if they [parents] participate, the quality of education will improve. education quality can be improved if the parents extend their financial support… if there is no proper involvement of parents, the school cannot run its function properly (director, private school, april 4, 2017). nevertheless, in spite of the invitations of directors, parents of government schools do not seem to be motivated to participate in the school management as expected. the following excerpts can illustrate the directors’ complaint in this regard: there is some reluctance on the parents’ side to come to school and accomplish their responsibilities. this happen because they have to run their personal business. here [in school] they give free service. so, parents show reluctance to come to school and give service (director, government school, april 4, 2017). the initiative on the parents’ side is not that much big, unless they are pushed by the school. parents need to be given awareness training on the importance of parental involvement in school management (director, government school, april 5, 2017). as can be seen from the above excerpts, parents need to be pushed to come to school. the two interviewees believe that parents have no time to participate in the school activities because they have to run their personal business. according to the directors, since parents gain no incentive for their contribution, they are less interested to work for schools. contrary to that of parents of government schools, parents of private schools seem to have good motivation to contribute their share towards the improvement of their children’s school according to some directors. now things have been changed a lot. they [parents] make serious follow up. they come to school and ask us about the school. …their initiation is very interesting. in my opinion, parents are playing their role properly (director, private school, april 7, 2017). the disparity between private school and government school parents in their involvement in school management reflects the reality in the literature. when the economic status of parents is lower, their participation in the school management becomes minimal (adam, 2005; shaffer, 1994). this could be one reason that prevents parents of government schools from involving in the management of their children’s school. on the other hand, since they pay for their children’s school, parents of private schools are interested to involve in school management to make sure that they are getting proper service for their money. according to some fgd participants in private schools, some representatives of parents in private school are also shareholders of the school. therefore, they actively participate in the management of the school to ensure the sustainability of their business. in other words, these parents are also economically better off compared to parents who send their children to government schools. in short, although they seem to have positive attitude and readiness to participate in the management of their children’s school, parents of government school lack commitment to do so. wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 35 table 2: attitude towards the actual involvement of parents in school management n.b: bold texts in parenthesis ( ) shows how the same item is phrased in the directors’ questionnaire the mean values of the parents and the directors on some of the items in table 2 indicate that there seem to be some differences between the two parties on the attitude of directors towards parental involvement in school management. for instance, the mean scores of the directors on item 1 (m=4.22, sd=0.62) indicate that directors always want to involve parents in the major decisions they make, whereas the mean score of the parents’ response on the same item (m=3.34, sd=1.24) is closer to “undecided”. the responses of both parties to item 2, (m=3.7, sd=1.15) for parents and (m=4.16, sd=0.59) for directors, show that principals are positive about the involvement of parents in the school management system. similarly, the mean values of the directors (m=1.28, sd=0.64) and that of parents (m=2.11, sd=1.11) on item 3 reveals that both parties disagree that principals make decisions alone and call parents for signature only. nevertheless, the difference in the mean value of the two parties on the last two items could be an indicator for the presence of some reluctance on the part of the directors in fully involving parents in school management. responses of both parties to item 4 show that school principals positively accept parents’ comments during school management meetings. however, there exist some difference between the response of parents (m=4.1, sd=0.77) and that of directors (m=3.6, sd=1.01). the response of the two parties to item 5 also shows that parents are happy about their involvement in the school management. the strong agreement of both parties to item 6, (m=4.29, sd=0.62) for parents and (m=4.25, sd=0.70) for directors, shows that parents need capacity building training to contribute their role in the school management. this may indirectly indicate the presence of knowledge gap among parents in contributing their share in the school management. in general, although both the directors and the parents believe that involving parents in the school management is important, the directors’ willingness in involving parents in the actual practice of school management does not seem to be satisfactory. such reluctance on the part of the directors may emanate from the directors’ underestimation of the parents’ knowledge about school system or their fear of losing authorities over the school management due to influence of some strong representatives of parents (guernsey, 2003; duma, 2009; mncube, 2009). 3.3. comparison of private and government schools on attitude of parental involvement in school management the results of the analysis of an independent samples t-test (see table 3) private school (m=3.39, sd=0.78) and government school (m=3.51, sd=0.31), t(2,33) = 0.25, p> 0.05) indicate that there is no statistically significant difference between directors of the two schools on their belief about the importance of parental involvement in school management. the analysis of similar test indicates the absence of statistically significant difference between the mean values of parents of the two schools on their belief about the importance of parental involvement in school management. sn items parents directors n m sd n m sd 1 the school principals (i) always want to involve parents in the major decisions made in the school 35 3.34 1.24 40 4.22 0.62 2 the school principals ( i am)are positive about parents involvement in the school management system 35 3.7 1.15 38 4.16 0.59 3 the school principals (i) make decisions alone and call parents for signature only * 35 2.11 1.11 40 1.28 0.64 4 school principals positively accept parents’ comments (parents make useful comments) during school management meetings 35 4.14 0.77 39 3.64 1.01 5 school principals are (i am) not happy about the involvement of parents in the school management * 35 1.69 0.90 40 1.63 0.84 6 parents need capacity building training to contribute their role in the school management 35 4.29 0.62 40 4.25 0.70 wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 36 table 3: private vs government secondary schools on attitude towards parental involvement in school management group statistics school type n m sd t df sig. (2-tailed) mean of directors private 20 3.3923 0.28 -1.177 33 0.25 government 15 3.5091 0.31 mean of parents private 20 2.7438 0.41 1.522 33 0.14 government 15 2.7833 0.23 3.4. domains of parents’ involvement in school management in the current study, eight items were included in the survey questionnaire to check the level and domains of parental involvement in the school management. table 4 shows that parental involvement in the governance of their children’s school is restricted to few domains. the mean values of parents’ response (m=4.1, sd=0.94) and that of directors’ (m=3.9, sd=68) on item 1 show that parents’ involvement in the management of school budget is high. the mean values of both parties on item 2 also reinforce the response on item 1. improving school infrastructure and maintenance and monitoring of the overall performance of schools are other areas where parental involvement is high. on the other hand, the mean value of the parents’ responses (m=1.40, sd=0.91) and that of the directors’ (m=1.25, sd=0.63) on item 4 affirms that the involvement of parents in the promotion of teachers is almost none. likewise, there is less involvement of parents in the management of students’ discipline, planning of activities of schools, and student recruitment, according to the parents. contrary to the parents’ responses, the directors, in their response to item 3 (m=3.97, sd=0.62), item 6 (m=3.88, sd=0.88) and item 7 (m=3.33, sd=1.9), claim that parents are actively involving in those areas. the researchers feel that the disparity in the responses of the two parties on these three items might have emanated from the directors’ desire to positively position themselves with regard to involving parents in the school management. to summarize, one can reasonably conclude from the above results that the roles that parents are playing in the school management is limited to financial issues such as controlling budget utilization, raising funds, and improving infrastructure of schools. contrary to the directors’ claim, the contribution that parents make in the core activities of schools such as planning the annual activities of schools, recruiting students, and management of students discipline is minimal. to use the word of watt (2001), the parents’ role in the target school management is limited to “monetary” support. regarding the domains of parental involvement, fgd and kii participants also reported that parental involvement is common in the areas of school infrastructure development, management of school fund and resolving students’ discipline. in relation to this, one of the key informants from a private school said, “parents work to improve the teaching learning processes, to improve the students’ performance by fulfilling the infrastructure of the schools. for example, there is shortage of chairs and blackboard. we talk with parents to resolve these problems” (director: private school, april 5, 2017). an fgd participant from government school also shares this opinion. he states, table 4: domains of parental involvement in the school management (out of 5) s.n areas of involvement parents directors n m sd n m sd 1 budgeting process of the school 35 4.14 0.94 40 3.95 0.68 2 raising finance/funds for the school 35 4.09 0.82 38 3.97 0.68 3 management of students’ discipline 35 1.54 0.82 40 3.97 0.62 4 promotion of teachers 35 1.40 0.91 40 1.25 0.63 5 improving school infrastructure and maintenance 35 4.08 1.48 39 4.03 0.67 6 planning annual school activities 35 1.57 0.85 40 3.88 0.88 7 student recruitment 35 1.34 0.64 40 3.33 1.19 8 monitoring the overall performance of schools 35 3.91 0.74 40 3.83 0.79 wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 37 “i participate in all the meetings of parents committee. the school has purchase plan. it has budget. it presents its budget plan to the committee. we supervise the purchase process and the bid process” (parent: government school, april 6, 2017). the finding of this study rhymes with the findings of some previous studies. studies so far conducted in this area revealed that community participation in school management in ethiopia is mainly limited to monetary support and kind contribution which can be used for improving school infrastructure and supplement salaries of part time teachers. the involvement of parents in school management decision making or teaching and learning was found to be minimal (obsaa, 2010; swift-morgan, 2006). 3.5. comparison on level of parental involvements as can be seen in table 5, the result of the analysis of an independent sample t-test, private (m=3.8, sd=0.89), government (m=4.47, sd=0.52), t (2, 33) =0.015, p <0.05) indicates that there is statistically significant difference between parents of private schools and that of government schools on their level of involvement in raising finance/funds for schools. similarly, the result of an independent sample t-test, private (m=1.85, sd=0.93), government (m=1.13, sd=0.35), t (2, 33) =0.008, p<0.05) indicates the presence of statistically significant difference between the two types of schools in the level of parental involvement in the area of students’ discipline management. the involvement of parents in private schools is higher than that of parents in government school. such difference might have emanated from the better awareness of parents of private schools on the importance of education for their children. these parents may also want to get good return for the money they invest. on the other hand, with regard to raising finance/funds for schools, parents from government school seem to have better involvement. this result indicates that since parents from private school are already paying the school fee, they may not be required to raise other funds. however, parents from government school are often asked to contribute for school infrastructure fulfillment where there are some shortages. however, there is no statistically significant difference between the two schools on other domains of school management. similar comparison made between responses of directors from the two types of schools on the level of involvement of parents in various domains of school management was also found to be statistically not significant. table 5: private vs government schools on level of parental involvement in the school management (parents response) group statistics items school type n m sd t df sig. (2-tailed) budgeting process of the school private 20 3.9500 1.09904 -1.416 33 0.166 government 15 4.4000 0.63246 raising finance/funds for the school private 20 3.8000 0.89443 -2.577 33 0.015 government 15 4.4667 0.51640 management of students’ discipline this school private 20 1.8500 0.93330 2.819 33 0.008 government 15 1.1333 0.35187 promotion of teachers private 20 4.0500 1.05006 -.262 33 0.795 government 15 4.1333 0.74322 improving school infrastructure and maintenance private 20 1.2500 0.55012 -1.413 33 0.167 government 15 1.6000 0.91026 planning annual school activities private 20 1.8000 1.00525 1.907 33 0.065 government 15 1.2667 0.45774 student recruitment private 20 1.5000 0.76089 1.728 33 0.093 government 15 1.1333 0.35187 monitoring the overall performance of schools private 20 3.7500 0.91047 -1.542 33 0.133 government 15 4.1333 0.35187 wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 38 3.6. factors that hinder parents’ involvement in school management there are several barriers to parental involvement in school management. according to adam (2005) and shaffer (1994), the sources of such barriers could be parents themselves or the school management. the same scholars categorize barriers related to parental involvement as economic conditions of the parents, existing political and institutional arrangements, and social and cultural condition. in the current study, the magnitude of six major barriers to parental involvement in school management has been checked. responses obtained from parents and directors on this issue have been summarized in table 6. the mean value for the parents’ response (m=3.91, sd=0.95) and that of the directors’ (m=2.68, sd=1.16) in table 6 show that lack of initiatives or interest among parents is a major barrier to parental involvement in school management. such type of reluctance on the parents’ side may emanate from their fear of interfering to school business or lack of motivation on the directors’ side in encouraging parental involvement in the core activities. on the other hand, both the parents and the directors strongly disagree or disagree that the remaining six factors are potential barriers to parents’ participation in school management. thus, one can reasonably conclude from this response that factors related to policy, parents’ level of literacy, lack of awareness on the importance of parental involvement in school management are not serious obstacles to parental involvement in the school management. participants of the fgds and kiis also indicate that parents’ reluctance is the major barrier to parental involvement in school management. this mainly emanated from the time constraint that the parents have. the following excerpts illustrate the existence of such problem: parents are not willing to come to schools when we call them to discuss on school problems. only some of them come and make decisions. later others say they do not know about the issue. sometimes three parents show up out of nine hundred. what does this mean? (parent (fgd), government school, april 7, 2017). a key informant from one of the private schools also state, “in our area, most of the parents are government workers. they do not have enough time. as a result of this, their participation in the school management is low.” (director: private school, april 6, 2017).the analysis of an independent sample t-test also shows that there are no statistically significant differences between government schools and private schools on factors that affect parental involvement in school management. this is may be because the parents in both schools live in the same socio-economic condition. similarly, no statistically significant difference has been seen between the responses of the directors in the two schools. 4. conclusion and recommendations 4.1. conclusions results of the current study reveal that both parents and directors have positive attitude towards parental involvement in school management. both parties responded that without the involvement of parents, schools hardly achieve their goals in delivering quality education. table 6: barrier to parental involvement in school management sn factors parents directors n m sd n m sd 1 lack of interest among school principals to involve parents 35 2.03 1.04 40 1.35 0.69 2 lack of initiative or interest among parents 35 3.91 .95 40 2.68 1.16 3 lack of clear policy on parents involvement in school management 35 1.60 1.03 40 1.43 0.75 4 parents’ low level of literacy about school management 35 1.66 0.94 40 1.55 0.85 5 lack of awareness among parents on the importance of parents’ involvement in school management 35 1.63 0.91 40 1.80 0.94 6 lack of awareness among directors on the importance of parents’ involvement in school management 35 1.43 0.82 40 1.58 0.84 wosene alemu et al. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 39 nevertheless, the actual practice on the ground seems to be different. parents’ involvement in school management is limited to school infrastructure development and financial management which includes raising funds for schools. the contribution that parents are making in the other domains of school management such as planning school activities, recruiting students and evaluating teachers’ performance, was found to be insignificant. time constraint, lack of awareness on how to take part in the school management, and reluctance due to lack of incentive package on the parents’ side and lack of willingness to practically involve parents on the directors’ sides were found to be the major barriers to parental involvement in the school management. the recommendation of both parents and directors for parents’ capacity building trainings could be considered as an evidence for parents’ awareness gap. other common barriers to parental involvement such as lack of clear policy and parents’ level of literacy do not seem to be common in the target schools. in the current study, comparisons were made to see if there are some differences between private schools and government schools concerning parental involvement in school management. results of the analysis of an independent sample t-test indicate that there is statistically significant difference between parents of private schools and that of government schools on the level of parental involvement in raising finance/funds for schools and managing of students’ discipline. parents of private schools seem to have better involvement in the management of students’ discipline, but less involved in raising fund for schools. this is true may be because parents who send their children to private schools have relatively better awareness on the importance of education for their children and thus strictly follow their discipline. on the other hand, results of an independent sample t-test reveal that there are not statistically significant differences between the two schools on the remaining domains of parental involvement in school management. this indicates the similarity of the scenarios in both types of schools. 4.2. recommendations in line with the above conclusions, the researchers would like to forward the following recommendations which may help in curbing the existing problems and improve the involvement of parents in school management: 1. the results of the study reveal that parental involvement is limited to few domains of school management such as raising funds, fulfilling school infrastructure and improving students discipline, but the literature in the area of parental involvement reveal that parents can play other major roles which include planning school activities, recruiting teachers, preparing teaching materials, and giving lectures. given their good educational background, some of the parents involved in the current study can make such contributions. therefore, school directors and woreda education offices need to devise mechanisms to enhance parental involvement in these domains. 2. time constraint, lack of incentives, and lack of awareness were found to be among the major barriers to parental involvement in school management. in order to curb these problems, school directors need to strengthen their ties with some local figures of the community and use them as bridges to encourage parental involvement. preparing awareness raising or capacity building trainings and designing incentives package for those representatives of parents could also help in encouraging parental involvement in the school management. 3. although there are no statistically significant differences between private schools and government schools on several domains of parental involvement in school management, parent from government schools can share the good experiences of private schools especially on the issue of managing students’ discipline. 4. finally, the researcher recommends further studies in the area with larger sample size. comparative study of schools from town and schools from rural districts could also be another topic for further 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(1997). improving school-community relations in the periphery. in h. d. nielson & w. k. cummings (eds.), quality education for all: community-oriented pproaches (pp. 37–78). new york: garland publishing. workineh abebe (2012). school management and decision-making in ethiopian government schools: evidence from the young lives qualitative school survey. uk: young lives. 50 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper the status of guidance and counseling service in ethiopian science and technology universities kumsa donis likisa  and jeylan aman tura school of humanities and social science, adama science and technology university, p. o. box 1888, adama, ethiopia article info abstract article history: received 19 december 2019 received in revised form 23 april 2020 accepted 16 may 2020 the main objective of this study was to explore the current status of guidance and counseling service in adama science and technology university (astu) and addis ababa science and technology university (aastu). by setting relevant criteria, the study attempted to identify the most appropriate model of guidance and counseling services for the study population. the main sources of information were six guidance personnel and 333 graduating students of the two universities. the guidance personnel were purposefully included in the study, while the students were selected randomly. to gather information from the respondents, questionnaires were developed based on the theories and circumstances affecting the provision of guidance and counseling in ethiopia. interviews with guidance and counseling unit heads were also used to substantiate the data obtained through the questionnaires. in the analysis of data, qualitative description of information from the open-ended questions and interviews were made. data obtained from close-ended questions were converted to statistics such as frequency and percentage and quantitatively interpreted. the study reveals that there is lack of effective institutional student counseling, guidance policy, programs, and facilities. there is also lack of awareness among the student population on the availability of guidance and counseling service in their campus and its benefits. it further highlights that there is lack of confidence in guidance and counseling service to solve students’ academic, career, personal, social, and psychological problems. overall, there is low status of guidance and counseling service in alleviating students’ problems. on the basis of the findings, some criteria in the selection of a model relevant to the ethiopian context were set. a model was developed and reviewed for two rounds by experts before it is taken for granted using delphi method. suggestions for further investigation were also made. keywords: university students guidance and counseling services guidance program resources 1. introduction guidance and counseling is an interaction process co-joining the counselee who is vulnerable and needs assistance and the counselor who is trained and educated to give this assistance. its goal is to help the counselee learn to deal more effectively with himself/herself and the reality of his/her environment (mubanga, 2014). guidance and counseling services aim at the personal, social, educational, and vocational development (collin,  corresponding author, e-mail: kumsalikisa@yahoo.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.166 2007; gatua, 2014) and self-actualization of individuals (kepceoglu, 1994) who have normal mental health (korkut, 2004). guidance and counseling services help in self-awareness, opportunity awareness, decisionmaking skills, and transition skills (watts et al., 1996; lussier, 2005; koul, 2006). njeri (2007) identified that the success of guidance and counseling program depends on administrators, teachers, http://www.ejssd.astu.edu/ mailto:kumsalikisa@yahoo.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 51 and parents’ support as well as allocation of adequate resources. students’ awareness of the role and importance of counseling contributes to the success of counseling services. if counselors had little training in guidance and counseling services, guidance and counseling program would face a number of challenges including lack of specific time allocation to guidance and counseling activities and lack of commitment of the actors. a successful guidance program contributes to students’ active engagement in learning and reduces negative outcomes such as failure, repetition, and dropout rate (collins, 2007; mikaye, 2012). thus, the provision of guidance and counseling in a university is not a matter of option; rather, it is a vital aspect of education that enables students to gain the maximum benefit from the education system, to make healthy interaction with their environment, and to be effective in meeting their various needs. however, the existing guidance and counseling services in higher learning institutions are found to be mostly nominal. a study by appiah (2013) on kwame nkrumah university of science and technology (knust) and ashesi university college in kenya indicated that both institutions have instituted guidance and counseling units to address the immediate and future needs of their students and to ensure the academic excellence of their students. however, at knust, the guidance and counseling approach and delivery was not motivating enough and the service was not as effective as anticipated. similarly, in ethiopia, in spite of the pressing need and the efforts made to rethink of provision of guidance, it appears that the existing guidance practice is not serving its desired purpose as needed. guidance and counseling services are largely inadequate due to absence of comprehensive guidance model and professionally qualified guidance counselors, lack of attention of universities to the program, high studentcounselor ratio, and inability of universities to respond to individual students in distress (yirgalem, 2013). yilfashewa (2011) also confirmed that, in ethiopia, there is a lack of systematically organized guidance in universities. limited attention has been given to academic, personal/social, and career guidance. guidance and counseling program could not support students’ acceptable behavior and promote emotional maturity, personality development, self-responsibility, creativity, and ability to solve problems. lack of students’ sufficient knowledge on the role of guidance and counseling, and role ambiguity, overwhelming workload and lack of continuous professional development by counselors (bunce & willower, 2001; brigman & campbell, 2003), lack of facilities and resources, and inadequate training of counselors are the other problems impeding the provision of guidance and counseling services in ethiopia. additionally, there are no policy guidelines on the use of guidance and counseling services. furthermore, lack of students’ awareness of the presence of guidance and counseling service and unfavorable attitude held by students towards seeking help determines how effectively counseling resources are used. a study by yilfashewa (2011) on haramaya university revealed that the students do not have adequate knowledge of the guidance and counseling services offered by educational institutions and nearly 52% of the participants perceive that guidance and counseling services have never reduced students’ academic, vocational, social, and personal stresses. yirgalem (2013) also indicated that the school community had poor awareness about the presence of guidance and counseling services at their schools. while students who tend to seek help are more likely to benefit from counseling, those who are doubtful of the importance of counseling are likely to enjoy little or no benefits from the service. a study by adane (2016) on the status of utilization of school guidance and counseling services in sidama zone secondary schools in ethiopia indicated a high counselor student ratio in the study areas and lack of awareness on the part of students about the service in their school. as stated earlier, most of the research carried out on the role of guidance and counseling service (e.g., yirgalem, 2013, selam, 2014 and adane, 2016) focus on high school and none has attempted to develop a model for guidance and counseling service. based on findings from various studies and the researchers’ personal observations, it is evident that some of the problems of students that need counseling intervention are low self -concept, lack of proper study skills, lack of time management skills, and inability of students to cope with various school challenges. other kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 52 problems are underutilization of the service, counselors’ professional incompetence due to lack of continuous professional development, lack of policy direction, and lack of institutional support and commitment. in ethiopia, there is a tendency to rely on traditional (nonprofessional) advisors. according to endrerud and charinet (2004), in ethiopia, youngsters get guidance and advice on their educational and social problems from older people, family members, and friends. religious institutions such as churches and mosques are also responsible in offering guidance services for their followers. compared to the long history of ethiopian education, the service of guidance counseling in ethiopian schools and higher learning institutions is at infantile stage. the service is offered mainly in secondary schools. it appears that guidance and counseling services at universities are not significantly contributing to students’ educational, vocational, and personal/social development. muango and joel (2012) indicated that lack of functional guidance and counseling contributes to indiscipline, drug abuse, immoral behavior, cheating in examination, unwanted pregnancies, rebellion, and maladjustment. the two science and technology universities under investigation are no exception in this regard. the stumbling blocks that prevail in ethiopian universities manifest themselves also in the two institutions. the main objective of this study is, therefore, to examine the status of guidance and counseling services in astu and aastu and develop relevant model that can be used by the two universities. conceptual framework this study was based on the premise that there cannot be students’ adjustment in a university without effective guidance and counseling services. in order for guidance and counseling to be effective, universities should have clear guidance policy and strategies, trained guidance and counseling personnel, and required facilities provided for guidance and counseling activities. besides the need for employing counselors’ and developing students’ positive attitude towards guidance and counseling services, the university administration itself should have a positive attitude towards the program and support provision of guidance and counseling services by allocating appropriate budget and assigning competent human power. moreover, both male and female counselors should be employed as the sex of the counselor is likely to matter most for clients seeking counselors’ support. counselors’ workload should be considered duly as it can also affect proper implementation of guidance and counseling service. there are two methods used for guidance and counseling in universities, namely, group/peer counseling and individual counseling. group counseling has an advantage over individual counseling in developing social skills so that students share experience and try out new styles with other members of the group. therefore, methods of counseling also interact with family factors, environmental factors, and personal factors to determine the level of students’ adjustment in a university setup. quality guidance and counseling services contribute to high level of students’ adjustment. figure 1 shows issues that need guidance and counseling interventions. the counselor can either use group, peer or individual counseling to counsel students that have problems emanating from family, environment, and personal factors. successful provision of educational, vocational, and social/personal guidance and counseling service depends on guidance policy, facilities and counselors’ qualification. 2. research design and methodology 2.1. research design this study used descriptive survey research design with mixed research approach that combines quantitative and qualitative research methods. mixed research method was used to obtain a more substantive picture regarding the complex nature of guidance and counseling services in students’ adjustment (williams, 2007). the decision to make use of this method was to generalize the findings from the sample to the entire population. the qualitative research method is principally aimed at obtaining verbal data to add meaning to numbers by exploring the meanings that people attach to their experience. qualitative research takes the form of a detailed and value-laden inquiry that focuses on the discovery, the processing, and the making of meanings kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 53 figure 1: conceptual framework of the study rather than on measuring the extent in terms of quantity (denzin & lincoln, 1994). for the purpose of this study, views and perceptions of the heads of guidance and counseling officers in the two institutions were gathered and examined. 2.2. study population and sampling the study population was students of ethiopian science and technology universities. multistage sampling technique was used to get the required study participants. first, schools/colleges were selected randomly; then, departments were selected using simple random sampling, and students within these departments were selected using simple random sampling technique using an official roster of the selected departments. the number of study participants in each department was determined by their proportion in the study population. the heads of guidance and counseling units and counselors in both universities were also included in the sample. accordingly, 192 out of 1804 students from astu and 141 out of 1405 students from aastu were selected. a total of 6 counselors were included in the sample. the two heads of guidance and counseling service unit were selected using availability sampling technique. 2.3. data gathering instruments to gather information from the informants, selfreporting questionnaires with close ended and open ended questions were developed taking into account the context of the study, guidance and counseling theories and practices. the questionnaire for guidance and counseling personnel focuses on guidance policy and/or guideline, guidance program, resources for guidance and counseling program, and challenges in the implementation of guidance and counseling service. the questionnaire comprises structured questions. it would enable the researchers to get relevant and consistent information about the current practices and challenges associated with the provision of guidance and counseling service. the questionnaire was validated by three psychology instructors before it was pilot tested and used as data collection tool for this study. the pilot study was conducted on 36 fifth year students prior to utilization of the instrument to collect data for the main study. following the pilot study, amendment was made on some items of the questionnaire. cronbach's alpha coefficient was used to measure reliability of the questions. cronbach's alpha coefficients for the questionnaire exceed 0.80 for attention of the universities to guidance and counseling service and challenges of guidance and counseling service parts. accordingly, reliability for attention of the universities to guidance and counseling service is 0.949, and it is 0.962 for challenges of guidance and counseling service. the high reliability of the items indicates the high level of dependability of the instrument to get the required information from the respondents. in addition to the questionnaire, interview was used as data collection tool to obtain information from two heads of guidance and counseling service unit in the two universities. 2.4. data collection procedure the data were gathered from students in a door-todoor situation by identifying their dormitories. for the purpose of data collection, four data collectors (two from each university) were recruited and trained for data guidance and counseling program  education/career counseling  psycho-social counseling  psychological counseling  counsellors’ professional qualification  students and counsellors’ attitude  support from the university  gender and workload of the counselor  guidance policy  facilities students’ adjustment independent variables intervening variables dependent variables kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 54 collection. they spent three to four days in data collection. interview was made on a face-to-face basis by the researcher using leading interview questions. 2.5. methods of data analysis the data collected through the questionnaire were organized and analyzed using descriptive statistics such as frequency, and percentage. in the analysis of data from the open-ended questions and interviews, the data were first transcribed and then organized into emergent themes, categories, and sub-categories. finally, they were integrated with quantitative data analysis. 3. results and discussions 3.1. results 3.1.1. students’ awareness and confidence in guidance and counseling service the selected students were asked whether they are aware of the availability of guidance and counseling service in their respective university, location of the service center, and the type of service offered and their tendency to seek support from the service. accordingly, their responses to the items are shown hereunder. as we can see from table 1, more than half (54.6%) of the respondents have reported that they are not aware of the availability of guidance and counseling service and 75.3% of them do not have information on the location of the guidance and counseling office. similarly, the majority (67.3%) of the respondents is not aware of the service offered and 75.3% do not have the interest to seek guidance and counseling service. these results indicate that an important ground has not been laid for the effective implementation of guidance and counseling service. awareness creation about the benefits of guidance and counseling service and motivating students to seek the service in case they are socially, behaviorally and academically challenged is found to be negligible. subsequently, the vast majority (91.7%) of students have never sought guidance and counseling service. only a total of 8.3% sought guidance and counseling service from one to five times. this problem may be attributed to students’ lack of awareness of the availability of guidance and counseling service and the type of service offered, and their lack of interest to seek guidance and counseling service. whenever they seek guidance and counseling service, some of their reasons are related to family problems, academic problems, peer pressure, problem in time management, inability to get psychological support from academic and administrative staffs, exam anxiety, feeling of helplessness, stress due to different socio-economic problems like regionalism, biases and discriminations, and instability in social interaction. it was further observed that most of the students (63.3%) do not feel comfortable to discuss their problems with counselors. students do not want to share their problems with counselors may be because of lack of trust on confidentiality of personal issues, and lack of confidence in whether guidance and counseling service solve their problems. there is a belief among students that counselors in the two universities cannot easily understand students’ problems and devise ways of tackling their psychological problems. the fact that previous counseling services had not been exemplary in their effectiveness on students’ behavioral change may have also contributed to students’ low interest in the service. table 1: students’ awareness of availability of guidance and counseling service (n = 333) no. item response percent 1. awareness of availability of guidance and counseling service yes 45.4 no 54.6 2. information on the location of guidance and counseling office yes 24.7 no 75.3 3. awareness of service offered yes 32.7 no 67.3 4. tendency to seek guidance and counseling service yes 24.7 no 75.3 kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 55 the majority of students didn’t have confidence in guidance and counseling services in positively influencing their academic performance (54.3%), dealing with their troubles and challenges in improving academic performance (57.4%), improving their interpersonal relations (54.6%), and solving all sorts of psychological problems (59.3%). as a whole, the overall students’ confidence in the benefits of guidance and counseling services is low. one of the students from aastu articulated: “…i have experienced all sorts of psychological problems, but none of them were fixed with counseling. they were fixed by faith. i am a better person now not because of counseling but because of jesus. the truth is i am who i am now because of christ.” another student from aastu also stated, “to tell the truth, if there were a strong counseling in aastu, i would be effective in my education. for a long time, starting from 1st year 2nd semester, i have been in a very stressful, depressed, and self-hating situation”. consistent with students’ unfavorable opinion about current counseling service, counselors in the two universities indicated that fewer than 100 students participate in the university guidance and counseling program per year. they hold the view that many students are not interested in guidance and counseling service. for instance, a participant had the following to say during the interview session: in spite of the availability of the service …, most students are not interested in seeking the service. i think sometimes students are embarrassed to ask for help. despite the availability of counseling services in universities, only a small number of university students (0.5% to 1%) who experience psychological distress seek professional counseling(participant 2). table 2: attention of the universities to guidance and counseling service (n = 333) response percent yes 22.8 no 77.2 total 100.0 the respondents were asked whether or not the universities take guidance and counseling service seriously. the majority of respondents (77.2%) feel that the two universities never take guidance and counseling service seriously. universities take guidance and counseling service as auxiliary rather than as their key duties and responsibilities. similarly, guidance personnel attested that inadequate attention is given to guidance and counseling services and no sufficient time is allocated to the guidance and counseling service. they have not taken any short training, refreshment courses, workshops, and other upgrading programs. all of them corroborated that they are not encouraged to engage in research activities to integrate theory and practice in guidance and counseling service. regarding the budget allocation, interviewee 2 stated “the university does not take guidance and counseling seriously as indicated by lack of budgetary allocation and facilities.” similarly, participant 1 revealed that “ineffectiveness of guidance and counseling services was caused by lack of support by administration, inadequate funds, and lack of clear guidance policy.” table 3: major guidance and counseling services provided (n = 333) from table 3, it is possible to understand that guidance and counseling service that is mainly provided is educational guidance (63.9%), followed by psychological guidance (16.4%). this implies that attention is not given to career and social guidance, which is also important in students’ selection of career paths, adjustments, and academic success. interview participant 2 also expressed that “educational guidance related to learning difficulties and time management and solving interpersonal conflict is emphasized to some extent. on the contrary, assisting students in department choice, learning about careers, choosing a career, job finding, and contacting jobrelated agencies, and organizing incoming speakers and arranging visits to outside events are ignored.” interview participant 1 also revealed that “more attention was given to academic achievement of the students rather than any other area. psychological and social guidance that promotes peace of the mind to create good chances for type of guidance and counseling service provided percent career guidance 9.0 educational guidance 63.9 psychological guidance 16.4 social guidance 10.2 other 0.6 total 100.0 kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 56 concentration in learning and that is useful in producing students who are disciplined and visionary in life is ignored.” he also elaborated that “vocational guidance, information services, placement services, consultancy and research services, appraisal services, evaluation, follow-up and referral services exist only nominally.” one of the interviewed counselors also articulated the issue as follows: in spite of the fact that duties of university counselors include providing instruction on psychological and social issues, attention was not given to vocational guidance, counseling, early intervention, and special needs services. negligible attention was given to maintain academic standards and set goals for academic success, train students on study habits, time management and social skills, maintain students’ discipline, and identify their interests, strengths, and aptitudes through assessment. the existing guidance and counseling service is not helping students resolve personal or interpersonal problems either through group or individual counseling as there is lack of guidance and counseling model (interview participant 1). 3.1.2. challenges in the provision of guidance and counseling service there are different challenges emanating from different sources and hampering the effective implementation of guidance and counseling service. in this study, attempts have been made to identify the challenge from various perspectives. the following section discusses challenges as indicated by the students. besides problems pointed out in section 3.1.1, there are challenges that obstruct the provision of guidance and counseling service. more than 50% of the respondents in all cases have reported the existence of challenges in student guidance and counseling practices. the first three very serious challenges as reported by the participants are students’ reluctance to take guidance and counseling correction seriously (66%), lack of knowledge on the benefits of guidance and counseling service (63.3%), and unsuitability of the location of the counseling office for privacy or confidentiality (56.5%). students’ feeling that they do not have time to use guidance and counseling service has also apparently contributed to challenges in the implementation of guidance and counseling service. according to interview participant 2, “guidance and counseling service is not helping in managing students’ behavior, reducing tensions and strikes in the university, realizing their mistakes, and developing positive attitudes towards the university.” he further elaborated that “there should be a shift from an ancillary, crisis-oriented service to a proactive, comprehensive guidance and counseling service that includes preventative and responsive activities and designed to meet the needs of the students it serves.” formulating a guidance policy and proper guideline has a desirable influence on the implementation of guidance and counseling service. however, the six guidance personnel maintained that their universities have no clear policy or guideline on how to employ guidance and counseling service in contributing to students’ learning and adjustment. the universities have no legal instruments promoting different aspects of guidance and counseling service. it seems that the guidance and counseling service in the universities tends to be voluntary rather than mandatory. there is no clear direction on whether guidance and counseling service should be given as a discrete course, or integrated with other courses, or as extended program through special activities. table 4: challenges of guidance and counseling service (n = 333) no. item response yes (%) no (%) 1. lack of knowledge on the benefits of guidance and counseling service. 63.3 36.7 2. students’ unwillingness to discuss their problems with counselors. 57.4 42.6 3. inconvenience of the location of the office for privacy or confidentiality 56.5 43.5 4. failure of students to take guidance and counseling correction seriously 66.0 34.0 5. lack of time to use guidance and counseling service. 50.0 50.0 6. lack of private room for guidance and counseling. 59.0 41.0 7. others 29.9 70.1 kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 57 the two interviewed heads of guidance and counseling service units unanimously agreed that there is no policy guideline at university level on how the university could use guidance and counseling to manage students’ behavior. besides the absence of guidance and counseling policy/guideline, the budget allocated for the guidance program was inadequate, and the program is not effective enough to address students’ educational, vocational and social/personal problems. all of the guidance personnel confirmed absence of a guidance curriculum designed to assist students to develop knowledge and skills appropriate for their personal, social and intellectual development. there are no computer programs and online services in students’ academic, personal-social, and career planning. there are also no peer counseling and mediation programs aimed to impact students’ misbehavior and reduce conflicts. the establishment of guidance program should be backed by allocation of appropriate resources. however, except on the availability of full-time counselors and office equipment, the majority of guidance personnel agreed on unavailability of resources for guidance and counseling program. the unavailable materials and resources include relevant software, audio and visual materials (resources), psychometric tests, student inventory, a handbook for different occupations, and so on. the interviewed heads of guidance and counseling units also agreed on the scarcity of resources which are meant for guidance and counseling services. lack of cooperation from administration and fellow staff members, lack of private counseling office (since two or more counselors share the same office), lack of funds/ budget to sponsor guest speakers and to attend workshops, inadequate number of counselors (1:1200 ratio), absence of guidelines, lack of counselors’ practical experience and motivation to render guidance and counseling service are the challenges encountered in implementing guidance and counseling service in the two universities. it was also found out that counselors lack professional experience, motivation, commitment, diligence, and willingness to support students as required. the other hindering factors in the implementation of guidance and counseling service are the fact that none of the guidance personnel were engaged in research activities to integrate theory and practice in guidance and counseling service. inconvenient location of the counseling office is also found to be an issue of concern. both astu and aastu counseling offices are located near a library and along students’ walkways. the interviewed guidance personnel confirmed that lack of policy and guidance program/curriculum, lack of awareness among the student community, inadequate resources, lack of cooperation from university management and teachers, and lack of commitment from counselors have obstructed effective implementation of guidance and counseling service. consequently, students could not develop appropriate social skills and a sense of belongingness to the university. this is manifested by bullying other students, disrespect for teachers, fighting, unwillingness to confess wrongdoings, theft, sexual harassment, damaging university property, and participating in student unrest. counselors are not also effective in preventing students from disciplinary problems such as aggressive and hostile behaviors, violent behaviors, committing crime, and many other inappropriate behaviors. hardly ever have they used counseling in their respective university to improve students’ academic achievement, reduce test anxiety, prevent students from dropping out of university, and reduce classroom disruptive behaviors, indiscipline or disturbances so as to enable them to focus on the teaching-learning process. in general, the guidance and counseling service is not designed in a way that addresses all students’ academic, personal, social, and career needs. specifically, 1) in ethiopian science and technology universities, there is ineffective institutional student counseling service characterized by absence of guidance policy, ineffective programs, scarce facilities, and generally poor provisions. . 2) guidance and counseling service is not organized in a way that ensures students’ welfare, adjustment and success. 3) some of the hindrances in effective implementation of guidance and counseling services in astu and aastu are student’s lack of awareness on the availability of guidance and counseling service and their negative perception and lack of confidence in guidance and counseling services in positively influencing their success, enabling them to deal with kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 58 their troubles and challenges, and solving other sorts of their psychological problems. lack of commitment from university management, absence of capacity building schemes, insufficient resources, and lack of clear guidance and counseling policy and/or guideline are the other problems that impede the implementation of guidance and counseling service. 3.2. discussion this study was aimed at examining the status of guidance and counseling service and its contribution to students’ adjustment in astu and aastu. in this section, the research findings generated from both quantitative and qualitative data are discussed in the light of the research objectives. when appropriate, the discussion is also made by relating the findings of the study to the literature, both local and international. 3.2.1. effectiveness of institutional student counseling, guidance policy, programs, and facilities the way guidance and counseling service is organized matters in its effectiveness. consistent with selam (2014), yirgalem (2013), adane (2016), yilfashewa (2011), majoko (2013), and pereira and rekha (2017), this study also reveals that there is lack of effective institutional student counseling, guidance policy, programs, and facilities part of provisions. the majority of student respondents feel that the two universities’ management considers guidance and counseling service as auxiliary activity rather than as its major obligation. similarly, the guidance personnel of both institutions revealed that inadequate attention is given to guidance and counseling services by university management, and there is lack of cooperation from fellow staff members. the guidance personnel were not given opportunity to be involved in upgrading programs; reasonable amount of budget was not allocated to run the guidance program, and sufficient time was not apportioned for guidance and counseling services in the two universities. what makes the problem more severe is the fact that the two universities do not have clear policy, guidelines, strategies, written plans, and specific roles and responsibilities that are useful in employing guidance and counseling services properly to contribute to students’ learning and behavioral change. there is also absence of guidance curriculum useful in students’ academic, personal-social, and career planning, and there is no clear direction on whether guidance and counseling service should be given as a discrete course, or integrated with other courses, or offered as extended program through special activities. consequently, there is a general lack of information and awareness about the benefits of guidance and counseling service among students. there is also students’ negative perception and lack of trust in the competence of counselors and effectiveness of the guidance and counseling services to solve their problems and counselors’ lack of professional commitment and diligence. besides, students lack information on the location of the guidance and counseling office, and the guidance and counseling service offices both at astu and aastu are located near a library and students’ walkways, a situation which makes the convenience and confidentiality of the service questionable. furthermore, the majority of the guidance personnel agree on unavailability of useful resources and facilities for guidance and counseling program including relevant software, audio and visual materials, psychometric tests, student inventory, and a handbook on career guidance. 3.2.2. hurdles in the implementation of guidance and counseling service in this study, a number of hurdles that have obstructed effective implementation of guidance and counseling service were identified. besides the absence of a guidance policy and curriculum and lack of support and facilities, there is lack of awareness of students about, and reluctance in, the use of guidance and counseling services. more than half of the students are not aware of the availability of the guidance and counseling services in their respective university and the type of services offered, while the majority of them do not have the tendency to seek guidance and counseling service, and the vast majority of students acknowledge that they have actually never sought guidance and counseling service. most of the students do not feel comfortable to discuss their problems with counselors may be because of lack of trust in confidentiality of personal issues and lack of confidence in the guidance and counseling service in solving their academic, vocational, personal, and social problems. this lack of trust and confidence of students in guidance and kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 59 counseling service might be attributed to experience gained from prior practice. in connection with this, ngii (2015) found that students may be motivated to, or discouraged from, seeking guidance and counseling services depending on their prior counseling experience. those who have had sound past experience in counseling process consider it positively. on the other hand, if the student had a bad prior counseling experience, he/she will develop negative attitude towards it. negative information about prior guidance and counseling intervention learned from significant persons and delayed changes in behavior may also be hinder students’ positive attitude towards the service. however, there are still quite many students who seek guidance and counseling services. where they need guidance and counseling service, it was mainly for problems related to academic issues (e.g., exam anxiety), family affairs, peer pressure, time management, feeling of helplessness, stress due to different socio-political problems like regionalism and instability in social interaction, biases, and discriminations. guidance and counseling services that are predominantly provided are educational guidance, followed by psychological guidance. it seems attention is not given to career and social guidance, which is also important in students’ selection of career paths, social adjustments, and academic success. the other hindering factors in the implementation of guidance and counseling service is the fact that guidance personnel were not engaged in research activities to integrate theory and practice, and that negligible attention was given to prevention and intervention programs in solving students’ educational, vocational, and social/personal problems. 3.2.3. useful criteria in the selection of relevant guidance and counseling model that supports students’ adjustment the following are essential criteria that have been identified from counseling theories and findings in this study to be potentially useful in establishing a relevant guidance and counseling model in the two universities:  identifying individual students’ problems through careful clients’ assessment, and selecting appropriate counseling techniques under the guidance of competent guidance personnel;  keeping in mind the multiplicity of personal and environmental influences, ranging from the immediate family to the wider community;  bringing into mind the interrelationship between guidance program and students’ adjustment;  keeping in mind that more than one counseling approaches can fit for different students and that an individual student may demand a mix of counseling approaches for the same problem;  being developmentally orientated and aware of the fact that counseling can be a lifelong process and involves a combination of interacting determinants;  establishing experience sharing scheme with someone who has already solved educational, vocational, and social/personal problems; having well established guidance policy guidance and counseling service, and ensuring that competent counsellors are assigned, awareness raising programs are in place, students have positive attitude towards the service, and university commitment and support are realized, all of which will ultimately determine students’ adjustment. 3.2.4. a model for guidance and counseling services in ethiopian science and technology universities on the basis of the criteria extracted from the literature and the findings of the study, the following guidance and counseling service model has been developed for the ethiopian science and technology universities. the model was developed using delphi method (crawford & wright, 2016). delphi method is useful in developing models by eliciting and refining judgments (consensus opinions) of anonymously recruited experts to avoid potential biases in the decision-making process by investigators. the steps in delphi method are number of iterations (two rounds in the case of this study), consensus, confirmed dissensus and finally stability of results. these steps were strictly followed and the researchers served as facilitators in collecting, composing, synthesizing and redistributing their varied responses for two rounds until the experts reach agreement. kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 60 figure 2: guidance and counseling service (gcs) model in ethiopian science and technology universities problem assessment  scrutinizing drawbacks of existing approaches  assessing existing problems, contexts and sources of individual or group problems awareness of alternatives  philosophies  theories  empirical research findings context based thinking process  reflective, critical and creative thinking  decision on approach(es)to be used valuing  appreciate the role of guidance and counseling service  formulating policy and developing guidelines  resource allocation  including guidance program in university’s plan and institutional evaluation schema  training for counsellors  awareness creation for students action  action plan, prepare contact plan and establish rapport  commitment and use of relevant counseling approach that address students’ educational, vocational, social/personal problems to enhance their problem solving capacity  motivating students and counsellors  building effective individual and group counseling skills  reflection in action evaluation  observation  workshop  reflection on and for action  report m o ti v a ti o n : r e co g n iz e a n d m a in ta in b e st g u id a n ce a n d co u n se li n g p ra ct ic e kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 61 effectiveness of guidance and counseling service depends on the status of the problem and the existing context (problem assessment), available alternatives, ability to contextualize the available alternatives, the value attached to the benefits of guidance and counseling service, and feedback from evaluation of the practice. problem assessment involves scrutinizing the drawbacks of the existing approaches and assessing the existing contexts and sources of individual or group problems. the existing approaches and status quo might not always solve all sorts of problems. dynamic and complex problems require vibrant and timely solutions. at the same time, the magnitude and source of the problem determine the selection of a guidance approach. the selection of guidance approaches requires awareness of alternatives. the philosophical stand of the counsellor, the theoretical framework utilized taking into account the dynamicity of a guidance approach from empirical research, and policy that gives direction will all matter in the effectiveness of guidance and counseling service. in other words, philosophical belief, selected theory, counseling technique employed, understanding empirical findings, and policy directives altogether critically determine counseling outcomes. context based thinking process/evaluation (reflective, critical, and creative thinking) should be made before the selection of a counseling approach. the selection of counseling approach should be accompanied by valuing/appreciating the role of guidance and counseling service. students and university management and community at large should give appropriate weight to guidance and counseling services. the university should include these services in its timetable/calendar and institutional evaluation scheme. formulating guidance and counseling policy, developing guidelines, and allocating resource give the necessary directions and strengths. the formulation of guidance and counseling policy and development of guidelines need to be accompanied by implementation. the implementation of guidance and counseling service requires developing an action plan, approaching users and establishing rapport with them, and applying a relevant counseling approach that enhances students’ adjustment and achievement. in this process, motivating students and counsellors, enhancing students’ problem-solving capacity, building effective individual and group counseling skills, and reflection in action and formative evaluation are important in improving the system of guidance and counseling service while it is on progress. summative evaluation should come at the end, and it can be made through observation, user focused workshop, reflection on and for action, and report. these will give feedback to improve or change the whole system. 4. recommendation based on the foregoing findings from the review of the literature relevant to this study and the empirical investigation, the following recommendations are proposed, whereby the effectiveness of guidance and counseling services in students’ academic, career, and personal/social needs may be addressed more effectively in ethiopian science and technology universities.  one of the problems in effective implementation of guidance and counseling service is lack of students’ awareness about its benefits and lack of their confidence in its effectiveness to solve their personal, social, emotional, behavioral, career, and academic problems. thus, there is a need for promoting guidance and counseling service by the counseling office using different means such as erecting promotion billboards at different parts of the university and using fliers, banners, leaflets, newspapers, brochures, and pamphlets to raise awareness of students. providing awareness creation workshops for students, delivering wellorganized and students’ need based counseling services like group or individual counseling, and guarantying confidentiality in the provision of the service are also important measures. there is a need to arrange an experience sharing program for students who are doubtful of effectiveness of guidance and counseling service to draw lessons from those who have got the service and solved their problems.  first year university life is crucial for students in their success in the succeeding years as it is a transition period from high school to university. they need to adjust themselves to the new social and academic environment. thus, there is a need for counselors to give more attention to freshman students and focus more on prevention and kumsa donis and jeylan aman ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 62 contributing to the improvement of the quality of teaching to avoid some academic stressors using alternative approaches like it (online counseling service), face-to-face counseling service by professionals, and student counseling committee at school/college level. psychoanalysis, behaviorism, person centered and systems theories can be applied separately or in combination based on the context of the problem. on the basis of these theories, counselors can focus on and offer training for students on life skills, social skills, conflict management, crisis management, communication skills, effective study methods, and emerging issues and behaviors in adolescence.  the counseling offices should create professional referral centres for students with issues beyond the counselors’ capacity.  the study results showed that adequate attention was not given to guidance and counseling service by the university management, and counselors could not get adequate updating and upgrading training. thus, universities need to give updating and upgrading training opportunities for counselors. training sessions may focus on theories and basic counseling skills, communication skills, educational, social/personal, and career guidance and counseling, developing positive attitudes, drug addiction, adolescence behaviors, and emerging issues. university administration should also take guidance and counseling seriously and allocate sufficient budget to cater for the programs and facilities. furthermore, university management should forge collaboration with the guidance and counseling office to improve students’ social/ emotional adjustment, warrant informed academic and career decision, avoid deviant behaviors of students to ensure discipline, and ensure mental stability and academic performance of students. finally, the university should develop a strategy to supervise the guidance and counseling service to ensure its effectiveness in addressing academic, social/emotional, and vocational issues facing students.  universities and counseling offices need to develop a clear policy, students’ counseling guidelines, and a handbook on professional ethics to run and manage guidance and counseling services effectively. starting at the macro level, guidance and counseling should become an integral part of educational policy. as changes take place in students’ behaviour, the guidance and counseling policy should be readjusted, so that the program that are undertaken on the ground can provide for developing changes in students’ behaviour. in line with the identified needs in students’ behaviour, the goals on the macro level (the policy level) can be publicized and become part of the programs that are undertaken at the lower levels. the policy should contain and keep in mind such contexts as the culture of the society, the psychosocial environment, and the socioeconomic circumstances.  finally, the researchers recommend the use of the model developed in this study in the two universities. studies that include more universities and a larger number of participants are recommended for comparison and for generalizability purpose. reference adane wako (2016). the status of utilization of school guidance and counseling services in ethiopian secondary schools in addressing the psychosocial and academic needs of secondary school students: 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(2007). research methods.journal of business & economic research, 5(3): 65–72. yilfashewa seyoum (2011). revitalizing quality using guidance counseling in ethiopian higher education institutions: exploring students’ views and attitudes at haramaya university, international journal of instruction, .4(2). yirgalem alemu (2013). assessment of the provisions of guidance and counseling services in secondary schools of east harerge zone and hareri region, ethiopia. middle eastern & african journal of educational research, 4(2): 28-37. 54 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (1), 2020 journal home page: www.ejssd.astu.edu.et astu research paper screening of some botanical insecticides against maize weevil, sitophilus zeamais motschlsky (coleoptera: curculionidae), on maize daniel getahun debelo1,  and mulatwa wondimu2 1department of applied biology, adama science and technology university, p. o. box 1888, adama, ethiopia 2melkassa agricultural research center, adama, ethiopia article info abstract keywords: quechers extraction method gc-ms cabbage khat. the effects of three, four, and five grams powders of seeds of azadrichta indica, millettia ferruginea and jatropha curcas, leaves of croton macrostachyus and euphorbia schimperiana were evaluated separately on 26 unsexed maize weevils treated with 100 g of the botanicals in each 250 cm3 glass jar arranged in rcd with three replications. a standard insecticide, pirimiphos-methyl 2% dust and untreated check were included for comparison. weevil mortality was recorded at 3, 7, 14, 21 and 28 days after treatment. during the last counting, both dead and alive weevils were counted and removed and the grains were kept under the same conditions for the emergence of f1 generation. the numbers of emerging f1 were recorded every other day for 33 days. seed germination was tested using 15 randomly picked seeds from undamaged grains from each jar. all the treatments showed significant difference (p<0.05) mortality from the control seven days after treatment. the cumulative mortality of all the treatments was very high (97.43–100%) while that of the control was 11.53, 28 days after treatment. the cumulative number of emerged f1 from the untreated control after 28 days was higher and significantly different from all the other treatments. seed germination test revealed over 77% seed viability with no significant difference among all the treatments. the study revealed that the botanicals caused high weevil mortality, very low fecundity and insignificant effect on seed viability. evaluation of the botanical powders against naturally infesting maize weevils should be conducted under farmers’ storage conditions. 1. introduction maize (zea mays l.) is a cereal grass related to wheat, rice, oat and barley; ranking second after wheat and is followed by third-ranking rice in order of world grain production. this plant is regarded as versatile with many uses and is cultivated in a wider range of environments than wheat and rice and any other crop because of its greater adaptability (asiedue, 1989; parugrug and roxas, 2008; onuh et al., 2008). maize is high yielding, easy to process, readily digested, and cheaper than other cereal (onuh et al., 2008).  corresponding author, e-mail: daniel.debelo@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i1.2020.149 maize is a very important cereal grain in africa where it is widely cultivated and consumed. it serves as a source of dietary carbohydrate for humans (asawalam et al., 2007). it is cultivated in ethiopia in diverse ecological conditions and constitutes about 17% of the total cultivated area and 24% of the grain produced in the country (csa, 1996). in ethiopia, maize is one of the major cereal crops grown for its food and feed values. it is one of the most important staple foods and cash crops providing calories for the consumers and http://www.ejssd.astu.edu/ mailto:daniel.debelo@astu.edu.et https://doi.org/10.20372/ejssdastu:v7.i1.2020.xx daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 55 income for the traders (waktole sori and amsalu ayana, 2012). although production of corn has increased to meet the global demand, several biotic and abiotic factors play an important role in limiting the productivity. among biotic factors contributing for storage losses, insect pests play a major role inflicting 20–30% damage of corn grain in tropical regions (haque et al., 2000) due to favorable conditions for their development and poor storage conditions (abraham tadesse, 1997). insects are most often considered as the principal cause of maize grain losses. the most important insect pests that cause damage to maize in the field and storage are lepidopterous stalk borers and coleopterous weevils, respectively. more than 37 species of arthropod pests are associated with maize grain in storage (waktole sori and amsalu ayana, 2012). initial infestations of maize grain occur in the field just before harvest and the insects are carried into the store where the population builds up rapidly. the huge post-harvest losses and quality deterioration caused by this insect pest is a major obstacle to achieving food security in developing countries (asawalam et al., 2007). insect pests which commonly attack stored grains like maize weevil cause severe damage to the commodity resulting in losses in weight, seed viability, and nutritive quality of foodstuffs (parugrug and roxas, 2008). sitophilus zeamais is one of the most destructive stored product pests of grains, cereals, and other processed and unprocessed stored products in subsaharan africa. it causes qualitative and quantitative damage to stored products, with grain weight loss ranging between 20 to 90% for untreated stored maize, and the severity of damage depends on factors which include storage structures and physical and chemical properties of the produce. heavy infestation of adults and larvae of maize weevil which cause postharvest losses have become increasingly important constraints to storage entomology and food security in the tropics (ojo and omoloye, 2016). the maize weevil is a major insect pest of stored maize in ethiopia. it causes substantial quantitative and qualitative loses manifested by seed perforation, and reduction in weight, market value and seed germination. losses ranging from 20 to 30% are common in some localities in the country. under farm-storage conditions in the bako area, up to 100% damage to maize stored for 6-8 months have been reported (girma demisie et al., 2008). in an assessment of insect store pests of maize in jimma zone of oromia regional state, waktole sori and amsalu ayana (2012) recorded maize weevil as the dominant species in all areas surveyed followed by angoumois grain moth (sitotroga cereallela), rice weevil (sitophilus oryzae) and flour beetle (tribolium confusum) and the pests are widespread, abundant and cause damage and loss to maize grain among the different arthropods. besides storage insect pests, a number of microorganisms attack maize in the field as well as in the storage and of these fungi are among the principal causes of deterioration and loss of maize grain (ominski et al., 1994). insects play an important role in infection of maize by fusarium spp. they can act as wounding agents or as vectors spreading the fungus from origin of inoculum to plants (dowd, 1998). borers and insects of the family nitidulidae are most often cited as favoring maize infection by fusarium species. the common control methods for this pest are the use of chemical insecticides, biological control, and botanical insecticides among others (ojo and omoloye, 2016). however, synthetic pesticides have been used for many years to control agricultural pests including those that damage durable food crops in storage like s. zeamais (girma demisie et al., 2008; tilahun fromssa and daniel hagos, 2016). they are effective in controlling pests yet expensive, dangerous to human health and may create other problems in post-harvest industry (parugrug and roxas, 2008). considerable problems may arise from the continued application of these insecticides which include high persistence, poor knowledge of application, pest resurgence, genetic resistance by the insect, lethal effects on non-target organisms in addition to direct toxicity to users, and increasing costs of application that subsistence farmers cannot afford (asawalam et al., 2007; girma demisie et al., 2008; tilahun firomsa and daniel hagos, 2016). these problems associated with the use of synthetic insecticides have necessitated research on the use of alternative eco-friendly cheaper insect pest control methods amongst which are the use of powdered plant parts and their extracts (asawalam et al., 2007). the current concerns of synthetic insecticides and the desire daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 56 for residue-free grains by consumers demand for searching and developing alternative management options to integrate with other control measures such as varietal resistance and botanicals. the use of botanical pesticides to protect plants from pests is very promising because of several distinct advantages. pesticidal plants are generally much safer than conventionally used synthetic pesticides. pesticidal plants have been in nature as its component for millions of years without any ill or adverse effect on the ecosystem. in addition, plant-based pesticides are renewable in nature and cheaper. also, some plants have more than one chemical as an active principle responsible for their biological properties. these may be either for one particular biological effect or may have diverse ecological effects. the chances of developing quick resistance to different chemicals are highly unlikely (parugrug and roxas, 2008). plant-derived pesticides can be transferred into practical applications in natural crop protection, which can help the small-scale farmers (parugrug and roxas, 2008). the use of natural and easily biodegradable crop protection inputs like azadirachtin can be a useful component of an ipm strategy since the compound is known for its low toxicity against beneficial insects (koona and njoya, 2004). therefore, the current study was undertaken to evaluate the insecticidal effect of powders of seeds of azadrichta indica and millettia ferruginea, leaves of croton macrostachyus, euphorbia schimperiana, and jatropha curcas as grain protectant against s. zeamais under laboratory condition. 2. material and methods 2.1. description of the study area this experiment was conducted at melkassa agricultural research center, entomology laboratory from february to may, 2018. the center is located at the central rift valley of ethiopia at 8o24’n latitude and 39o21’e longitude and at an elevation of 1550 m above sea level and the mean relative humidity is 80%, and it receives annually 763 mm rain falls. the maximum and minimum annual mean temperatures are 28.4oc and 14oc respectively (marc, 1996). according to the recent agro-ecological zones classification of ethiopia (moa, 2000), the melkassa hypo calcic regosol ecotope falls in the zone termed hot to warm semi-arid lowlands. loam and clay loam soil textures are the dominant textural classes (marc, 1995; tsion et al., 2009). 2.2. plant material collection and preparation five locally available plants including seed of azadrichta indica a. juss (collected from dire dawa city), seed of millettia ferruginea (hochst) baker (collected from addis ababa city), leaf of croton macrostachyus hochst (from adama district), leaf of euphorbia schimperiana scheele (from adama district), and leaf of jatropha curcas l. (collected from compound of melkassa agricultural research center) were evaluated to determine insecticidal effect as grain protectant against sitophilus zeamais. these plant materials were air-dried under shade, pulverized separately into a fine powder using micro plant grinding machine and sieved through a 0.25 mm (250 μm) pore size mesh sieve to obtain uniform fine dust particles. each plant material was kept in a plastic bag in a cool place until treatment. 2.3. insect rearing parent adult maize weevils were obtained from melkassa agricultural research center. following the methods used by girma demisie et al. (2008) and bekele jembere et al. (1995), maize weevils were cultured under laboratory conditions at 27±2°c, 60-65% r.h. and 12:12 h light:dark regimes on whole clean, undamaged and uninfested maize grain variety melkassa 2 provided by the research center. the grains were washed from impurities using distilled water, dried and disinfested by keeping in a deep freezer at -20 ± 2°c for 96 h. after disinfestations, the seeds were cleaned and kept for two weeks at the experimental conditions for acclimatization and adjusted to moisture contents of 12 to 13% before use. two kilograms of the disinfected seeds were placed in four-liter capacity plastic containers covered with perforated lids and replicated 10 times. about 800 unsexed adult maize weevils were introduced onto the grain in each plastic container and kept to oviposit for two weeks, after which they were removed and discarded. the grains were kept for progeny emergence to be used for the experiment. 2.4. treatment application three different rates 3, 4 and 5 g, equivalent to 3, 4 and 5%, respectively, of each of the five botanicals were daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 57 weighed separately and added to each 100 g of clean maize put in each 250 cm3 glass jar and shook well manually for uniform mixing. a standard insecticide, pirimiphos-methyl 2% dust (2 g) and untreated check were included for comparison. the experiment was laid out in a complete randomized design (crd) with three replications. twenty-six newly unsexed emerged adult weevils (one day old) were placed in each jar and covered with muslin cloth held in place with rubber bands. the jars were kept in the laboratory at room temperature (25 ± 2 °c and 60-65% r.h. and 12:12 h light: dark regimes). 2.5. data collection 2.5.1. weevil mortality weevil mortality was recorded 3, 7, 14, 21, and 28 days after initial infestation (dai) based on girma demisie et al. (2008) and dead weevils were counted and discarded each time. during the last counting, both dead and alive weevils were counted and removed and the grains were kept under the same conditions for the emergence of f1 generation. 2.5.2. f1 progeny emergence after removing dead and alive weevils, the seeds were kept under the same conditions for the f1 progenies to emerge. the numbers of f1 progeny weevils emerged were recorded every other day and were stopped after 33 days (60 days, dai) to avoid overlapping of generations. 2.5.3. seed germination test seed germination test was performed at the end of the f1 progeny for all the treatments to check the effect of the botanicals on germinating power (seed viability) of the seeds. accordingly, 15 undamaged grains (seeds without visible holes) were randomly picked from each treatment and placed on a moistened filter paper in petri dishes replicated three times and the numbers of germinated seeds were recorded after seven days and the percentage germination was computed. 2.6. data analysis adult weevil mortality data in each replication was expressed as a percentage of the total number of adult weevils introduced, f1 progeny emergence of each replication was counted and computed as means, and seed germination was computed as percentage. prior to statistical analysis, data on percentage mortality were arcsine-transformed, while percentage of seed germination and the number of f1 progeny emergence were square root-transformed to reduce variance heterogeneity (gomez and gomez, 1984). all data were analyzed using one-way analysis of variance (anova) model by sas software, version 9.2 package (sas, 2008). treatment mean separations were conducted using student-newman-keuls test (snk) at 5% level of significance. 3. results and discussion 3.1. effect of botanicals on parent adult weevil mortality the results of the effects of the botanical treatments on weevil mortality at different days after treatment application are depicted in table 1. azadirachta indica, m. ferruginea and j. curcas relatively inflicted higher weevil mortality than c. macrostachyus, e. schimperiana, and the untreated control three days after infestation. only the chemical insecticide, pirimiphosmethyl 2% dust, caused 100% weevil mortality within three days of treatment application, whereas, the efficacy of the botanical powders increased with exposure time and the cumulative mortality was found to be very high and no significant difference (p<0.05) was found among the botanicals and the chemical insecticide 28 days after treatment application. seven days after treatment application, all the treatments showed significant difference (p<0.05) from the untreated control at all rates (3, 4, and 5 g w/w, i.e., 3, 4 and 5 %, respectively). at all rates of application, there was no significant difference (p>0.05) among c. macrostachyus, e. schimperiana and m. ferruginea, and the untreated control three days after application. however, significant different (p<0.05) mortality was observed between these botanicals and the control with exposure of time. except c. macrostachyus, e. schimperiana and m. ferruginea, the rest of the botanical treatments and the chemical caused 100 % weevil mortality 14 days after treatment. however, 28 days after treatment application, high percentage of mean cumulative mortality (97.43 – 100 %) was recorded by all the botanical treatments at all rates and there was no significant difference (p>0.05) daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 58 among all the botanical treatments and the standard chemical, whereas a significant difference (p<0.05) was recorded between all these treatments and the untreated control (11.53%). there was almost no significant difference (p>0.05) among the different rates of each of the same botanical treatment in their mortality effect and this indicated that the lowest rate was as effective as the highest rate. the results showed that the mean cumulative percentage mortality inflicted by all the botanical powders at all rates was almost as effective as the synthetic chemical insecticide, pirimiphos-methyl 2% dust at 2 g, differed only in their speed of action and this revealed that the botanicals had profound effect comparable with the standard insecticide. thus, the results of this showed that the botanicals can be used by resource poor farmers for the management of maize weevil. in a similar study, asmare dejen (2002) recorded a percentage mean cumulative mortality of 84.40% with seed powder of a. indica, 48.90% of c. macrostachyus, 100 % with leaf powder of jatropha curcas and 34.5% with leaf powder of m. ferruginea 28 days after infestation at 50 g/100 kg (5%) of each botanical product on sorghum. except leaf powder of j. curcas, the mortality effect of rest of the products is lower than that of the current study. in the current study the seed powder of j. curcas (at 3, 4, and 5%) inflicted 100 % weevil mortality 14 days after infestation which may show that the seed powder is more toxic than the leaf powder. in a different similar work, kifle gebreziher et al. (2016) reported that neem seed powder both at 5 and 10% rate caused 100 % maize weevil mortality on sorghum seven days after treatment and the effect of 2.5% increased with exposure time and achieved 100% mortality after 21 days after treatment application. botanical extracts kill and repel pests, affect insect growth and development, have antifeedant and arrestant effects, and have antifungal, antiviral and antibacterial properties against pathogens. botanical insecticides have long been touted as attractive alternatives to synthetic chemical insecticides for pest management because botanicals pose little threat to the environment or to human health (said and pashte, 2015). the use of plant products as protectants could offer a solution for the problems of availability, health risks, costs and resistance over synthetic pesticides (said and pashte, 2015). table 1: percentage mean mortality of maize weevil on maize grains treated by powders of different botanicals at different rates after different days of initial treatment application percent mean weevil mortality days after treatment application treatments rate/g 3 7 14 28 (cumulative) azadirachta indica 3 4 5 57.69b 30.77cd 44.87bc 42.30b 69.23ab 53.84b 100.00a 100.00a 67.95ab 100.00a 100.00a 97.43a croton macrostachyus 3 4 5 2.57d 0.00d 3.84d 35.90b 78.20ab 74.36ab 32.07b 16.67b 16.67b 100.00a 94.86a 94.86a millettia ferruginea 3 4 5 28.20cd 28.20cd 21.79cd 44.87b 52.56b 58.97b 21.07b 28.85b 52.56ab 97.43a 100.00a 100.00a euphorbia schimperiana 3 4 5 3.84d 0.00d 0.00d 57.69b 53.84b 55.13b 23.07b 21.79b 30.77b 97.43a 100.00a 100.00a jatropha curcas 3 4 5 38.46bc 38.46bc 34.61bc 61.34b 61.34b 65.38ab 100.00a 100.00a 100.00a 100.00a 100.00a 100.00a pirimiphos-methyl 2 % dust 2 100.00a 100.00a 100.00a 100.00a untreated control 0.00d 1.28c 8.97b 11.53b cv 41.68 26.33 37.88 2.76 means with the same letter in the same column are not significantly different at α = 0.05 daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 59 tloba and ekrakene (2006) reported that the mortality caused by different plants could be attributed to several mechanisms. the use of plant powders could have resulted to death as a result of physical barriers effect of the plant materials. this is because the powder has the tendency of blocking the spiracles of insects, thus impairing respiration leading to the death of insects. while feeding on whole grains by the weevil (s. zeamais) or the larvae might pick up a lethal dose of the treatment thus resulting in stomach poisoning. schmutterer (1990) stated that azadirachtin has deterrent, antifeedant, growth disrupting, antiovipositional and fecundity reducing properties on a range of insects. bekele jembere (2002) evaluated the toxicity of millettia seed against s. zeamais and reported higher mortality of the weevil within 48 hours after treatment. rotenone is one of the dominant compounds found in the seed and stem bark of millettia, and is a well-known botanical insecticide through contact and stomach poisoning (saxena 1983; bekele jembere, 2002). it is also highly toxic to fish and soluble in polar solvents (bekele jembere, 2002). tebkew damte and mekasha chichaybelu (2002) also tested the toxicity of millettia seed against adzuki bean beetle (callsobruchus chinunesis) and found that it gave complete protection of stored chickpea for six months in the laboratory, even though it was not effective in controlling this storage pest when used by farmers. it deterred egg-laying. bayeh mulatu and tadesse gebremedhin (2000) reported from their laboratory study that the oils of m. ferruginea and a. indica were able to effectively control adzuki bean beetle infestation of faba bean by partially or completely preventing egg-laying, and no bruchids emerged from the few eggs laid. in a laboratory test of j. curcas seed powder at 1.00, 2.00 and 3.00 g/100 g (1, 2, and 3 %) against maize weevil, ojiako et al. (2014) reported that the seed powder at the highest rate (3.00 g) inflicted adult mortality 6.67, 40.00, 70.0 and 100 % after two, three and seven days of infestation, respectively, with lowest adult emergence (0.67 2.67). the mortality effect of the other lower rates of the seed powders (1 and 2 g) increased with exposure time, i.e., the 1 g seed powder caused 0.00, 16.67, 53.33 and 83.33 after 1, 23, and 7 days, respectively, while the 2 g caused 3.33, 23.33, 66.67 and 90.00 % after one, two, three and seven days, respectively. 3.2. effect of botanicals on emergence of f1 progeny the mean number of f1 progeny (emerged adults) from the maize grains treated with three rates of different plant powders and a standard insecticide is presented in table 2. on the first day of observation, no progeny was emerged from all the treatments except in the untreated control. in a. indica, j. curcas and chemical treated grains, no progeny were emerged after 28 days. the mean number of f1 progeny throughout the observation period from all the botanical treatments at different rates was very low and there was a significant difference between all the other treatments and the untreated control. the very low/and absence of f1 progeny emergence from the botanically treated grains may be associated to the very high mortality of the treated weevils. the mortality effect of all the treatments was very high (97.43-100%) as compared to the untreated control (11.53) (table 1). adult weevils did not emerge from treated maize with a. indica and j. curcas at all rates unlike the other botanical treatments (table 2) and this may indicate that besides causing high weevil mortality, the botanicals have significant effect on insect fertility. in line with the present findings, dekeba moges et al. (2016) reported a reduction in f1 progeny emergence in botanically treated grains which might be due to increased adult mortality, ovicidal, and larvicidal properties of the tested botanical powders. the absence of adult weevil or f1 emergence indicated the efficacy of the botanicals for the control of maize weevil. the botanicals caused high mortality of s. zeamais on one hand and completely hindered or significantly reduced progeny emergence on the other hand, indicating its potential use in the management of maize weevil. these findings coincide with the work of dagna et al. (2015) who reported that botanicals such as neem seed powder completely hinders progeny emergence, percentage seed damage and seed weight losses caused to maize grains by maize weevil, probably due to the huge array of azandirachtin activities on the insect’s hormone system. in a similar work by kifle et al. (2016), no progeny was also emerged from sorghum treated by 5 and 10 % neem seed powder. daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 60 table 2: mean number of f1 progeny of maize weevil emerged from treated maize by different botanicals at different rates and percentage mean germination of treated seeds f1 progeny emergence germinated seeds (%) treatments rate/g 1 day 2 days cumulative after 28 days azadirachta indica 3 4 5 0.00b 0.00b 0.00b 0.00c 0.00c 0.00c 0.00c 0.00c 0.00c 97.78a 88.89a 91.11a croton macrostachyus 3 4 5 0.00b 0.00b 0.00b 1.33c 1.00c 0.33c 1.33c 1.00c 0.33c 95.55a 82.22a 75.55a millettia ferruginea 3 4 5 0.00b 0.00b 0.00b 0.00c 1.00c 1.33bc 0.00bc 1.00bc 1.33bc 84.44a 100.00a 97.78a euphorbia schimperiana 3 4 5 0.00b 0.00b 0.00b 0.67b 1.67bc 1.00c 0.67b 1.67bc 1.00c 95.56a 93.33a 91.11a jatropha curcas 3 4 5 0.00b 0.00b 0.00b 0.00c 0.00c 0.00c 0.00c 0.00c 0.00c 88.89a 77.78a 82.22a pirimiphos-methyl 2 % dust 2 0.00b 0.00c 0.00c 97.78a untreated control 1.33a 4.67a 6.00a 91.11a cv 178.69 77.69 74.27 13.67 means with the same letter in the same column are not significantly different at α = 0.05 3.3. effect of botanicals on germination of seeds there was no significant difference (p>0.05) percentage mean seed germination among all the treatments. however, relatively lower rate of germination was recorded in croton macrostachyus (75.55 % at 5 % rate) followed by j. curcas (77.78 % at 4 % rate) treated seeds (table 2). the higher percentage mean mortality of the botanically treated maize grains and higher seed germination in all the treatments indicated that the botanicals can control the maize weevils and none of the botanicals significantly affected the germination (seed viability) of the maize grains. this indicated that resource-poor farmers can use the botanicals for the control of maize weevil and also use the treated grains for planting the grains. in a similar work, asmare dejen (2002) also reported that powders of datura stramonium, j. curcas, phytoloca dodecondra and a. indica did not show any visible adverse effect on germination capacity of the grains. this is also in agreement with the findings of ojiako et al. (2014) who reported that j. curcas seed powder does not have negative effects on the viability of treated seeds and found that percentage mean germination of treated seeds was 93.00, 90.00 and 96.67 % treated with 1.00, 2.00 and 3.00 ml of seed powder, respectively. 4. conclusion and recommendation the current study revealed that all the botanical powders tested against maize weevil caused very high adult weevil mortality and also highly affected their progeny production (fertility) which revealed their insecticidal activity. besides, the botanicals did not affect significantly the germination capacity of the treated seeds. therefore, all these qualities of the botanicals can be considered for potential use of their powders in the management of s. zeamais under subsistence farmer’s storage conditions. however, evaluation of the botanical powders against naturally infesting maize weevils under farmers’ storage conditions should be conducted. the results of the current study showed that generally there was no significant difference among the different rates (3, 4, and 5%) of each botanical powder on the weevil mortality and progeny emergence. therefore, further study is necessary to identify the minimum effective concentration of the botanical insecticides which can cause maximum weevil mortality. daniel getahun and mulatwa wondimu ethiop.j.sci.sustain.dev., vol. 7 (1), 2020 61 acknowledgments the authors acknowledge adama science and technology university for funding the research and melkassa agricultural research center for providing maize grains, adult maize weevils and all lab facilities for the experiment. we also wish to thank mrs. meseret getachew and firehiwot lemma for their assistance in the lab, dr. gashawbeza ayalew and mr. abiy fikadu for their technical support in data analysis. references abraham tadesse. 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(2009). farmers training programme of ethiopian institute of agricultural research: an appraisal. african journal of agricultural resource, 4: 409-421. waktole sori and amsalu ayana (2012). storage pests of maize and their status in jimma zone ethiopia. african journal of agricultural research. 7(28): 4056-4060. 29 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9(1), 2022 journal home page: www.ejssd.astu.edu.et astu research paper application of quality function deployment in customer oriented footwear development process hailu beyecha deti, habtamu beri, biftu hailu, kemal temam mechanical engineering department, school of mechanical, chemical & materials engineering, adama science and technology university, p.o. box: 1888, adama, ethiopia article info abstract article history: received 15 june 2021 received in revised form 11 january 2022 accepted 16 march 2022 the main purpose of this study was to develop the house of quality in footwear development process. the study was conducted using quantitative research method. both primary and secondary data sources were used. the primary data sources were sampled using purposive sampling method. the tools used for collecting the data were informant interview and questionnaire. the secondary data were collected from previous research outputs that are related to the application of quality function deployment in footwear development process. the collected data were analyzed using microsoft excel 2016 and qfd capture professional edition 4.2.20. the analysis results revealed that the footwear produced by ethiopian companies fared below par in comparison to the footwear produced by chinese and european companies in terms of customer and technical perspectives. therefore, ethiopian footwear manufacturing companies shall use the prioritized customer and technical requirements in order to develop customer oriented footwear. keywords: customer orientation quality function deployment house of quality footwear 1. introduction nowadays, manufacturing industries, particularly footwear manufacturing industries are operating in a very competitive and dramatically changing environment (united nations, 2018; alina and alexandra, 2018). in order to survive in such an environment, the industries have to develop a betterquality product with a reasonable cost and faster delivery time (alina and alexandra, 2018). for improving quality, reducing cost and shortening delivery time of a product, manufacturing industries were using different quality techniques (radej et al., 2017). among the techniques, quality function deployment (qfd) was the one that was used by many industries throughout the globe in order to enhance customer satisfaction (eshan, 2012; alina and corresponding author, e-mail: beyechahailu@yahoo.com https://doi.org/10.20372/ejssdastu:v9.i1.2022.381 alexandra, 2018; chatree et al., 2012). according to niguss haregot and kassu jilcha (2019), firms can improve quality of products, minimize costs and shorten product development time through the introduction of qfd. qfd is an engineering method used to improve quality by considering the voice of the customer (or customer requirements) in the product development process, according akao (1990), the founder of qfd. moreover, qfd is a method used to transform customer demands into design quality, to deploy the functions forming quality, and to deploy methods for achieving the design quality into subsystems and component parts, and ultimately to specific elements of the manufacturing process (eshan, 2012). additionally, qfd is a technique http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i1.2022.......... hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 30 used to improve quality of a product by focusing on the requirements of the customer. qfd is further used to translate customer requirements into technical requirements of the product by considering benchmarks and regulatory standards (fiorenzo and domenico, 2018). qfd is also considered as a method that is used by applying a graphic model named as house of quality, hoq (akao, 1990; karin and john, 1996; anusha, 2010; sanchit and vivek, 2015). the hoq is a type of conceptual map that offers the means for interfunctional planning as well as communications during the product development process (praveen, 2016). moreover, hoq is a qfd tool that is used to identify customer requirements and determine technical requirements in order to satisfy customer requirements. on the contrary, qfd has not been well introduced to the ethiopian industries yet (niguss haregot and kassu jilcha, 2019). as a result, the industries are less competitive in the local and global markets due to poor product quality and high product cost (niguss haregot and kassu jilcha, 2019). therefore, this is the rationale for delving into the study as it is high time to introduce customer oriented footwear development process through the application of qfd. 2. methodology in this study, a quantitative research method had been employed. both primary and secondary data were collected and used in order to conduct the study. the primary data were collected through informant interview and questionnaire. the informant interview was used to identify customer requirements with regard to footwear from potential customers and lead sellers at different areas of adama city such as 'amede', 'franko' and 'mebrat hail'. the questionnaire was used to determine the importance to customer and customer competitive assessment from the respondents' point of view. the respondents were selected purposively based on their experiences of using footwear made in ethiopia, china and europe. additionally, the secondary data were collected so as to account for the regulatory standards of footwear development process. the secondary data were obtained from different literatures and previous research outputs such as journals, periodicals and articles. the scale used for the design of the questionnaire is the likert scale (ankur et al., 2015) with the range from one (1) to five (5); one (1) stands for the very low importance and five (5) for the very high importance. the questionnaire was distributed to the purposively selected permanent workers of adama science and technology university (astu). currently, there are about 2,222 permanent workers in astu (irccd, 2020). therefore, the sample size of the respondents was determined by using simple random sampling method with the slovin's formula (equation 1) (thomas, 2013): n = n 1+n(e)2 (1) where, n = sample size, n = total population and e = sampling error at 90% level of confidence. therefore, n = 2,222 1+2,222(0.1)2 = 96 as a result, 120 questionnaires were distributed to the respondents and finally 99 questionnaires were properly filled and returned from the respondents. thus, the response shows that the data were strongly reliable at 90% level of confidence. with regard to the demographic characteristics of the respondents, nearly 96% of the respondents were male respondents and the remaining 4% were female respondents. additionally, the age range of the respondents was varying from 26 – 59 years of age with their education level of 35%, 54% and 11% that stand for first degree, second degree and third degree, respectively. then after, the data obtained from the questionnaire were analyzed and presented by using the house of quality (hoq) technique, the main analytical technique used in the qfd (yoji akao, 1990). in hoq, customer requirements are translated into technical requirements by considering the regulatory standards of footwear development process. therefore, qfd capture professional edition 4.2.20 was used to construct the results of the study based on the steps that required for the development of the hoq (praveen, 2016; alina and alexandra, 2018). additionally, microsoft excel 2016 was used to determine the average and percentage results of the study through descriptive statistical analysis method. hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 31 3. results and discussion 3.1. determination of customer requirements four primary and twenty secondary customer requirements were generated based on the responses of the customers and lead sellers of footwear that were made in ethiopia, china and europe. furthermore, the average importance to customer and customer competitive assessment were determined from the responses of the respondents by approximating the digits below 0.5 to the lower full number and higher 0.5 to the next full number with the range from 1 to 5. the comparative percentage of the primary customer requirements was also determined among the primary customer requirements and the competitors as shown in table 1. table 1 shows the list of customer requirements with the average results of the importance to customer and customer competitive assessment of footwear that were made in ethiopia, china and europe. in the importance to customer, the primary customer requirements such as performance, comfort, appearance and availability weighs the value of 25.71%, 25.58%, 24.36% and 24.36%, respectively. in the customer competitive assessment, european footwear weighs the highest value in most of the primary customer requirements such as comfort, appearance and performance with 40.00%, 39.58% and 37.50%, respectively. however, chinese and ethiopian footwear weigh the same higher value in the case of availability with 34.78%. moreover, ethiopian footwear weighs higher value (33.65%) in the case of performance when compared with the chinese footwear that weighs lower value (28.85%). table 1: customer requirements, importance to customer and customer competitive assessment # customer requirements average importance to customer (1 – 5) average customer competitive assessment ethiopia (1 – 5) china (1 – 5) europe (1 – 5) primary secondary 1 comfort soft and flexible 4 3 4 5 2 allow free movement 4 4 4 5 3 good fit on foot 5 4 4 5 4 thermal comfortability 4 3 3 5 5 light weight 4 3 4 4 comparative percentage 25.58% 28.33% 31.67% 40.00% 6 performance durable 4 4 3 5 7 good adhesion of outsole 4 4 3 5 8 not fabric fungi problem 5 4 3 5 9 not make skin irritation 5 3 3 4 10 protection against hazards 4 4 3 4 11 slip resistance 4 4 3 4 12 easy to lock and unlock 4 4 4 4 13 easy to don/doff 4 4 4 4 14 easy to polish 4 4 4 4 comparative percentage 25.71% 33.65% 28.85% 37.50% 15 appearance fashionable 4 3 4 5 16 good look 4 3 4 5 17 nice finish 4 4 4 5 18 wide colour range 4 3 4 4 comparative percentage 24.36% 27.08% 33.33% 39.58% 19 availability wide size range 4 4 4 4 20 reasonable price range 4 4 4 3 comparative percentage 24.36% 34.78% 34.78% 30.43% hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 32 table 2: target value and sales point of customer requirements # customer requirements target value (1 – 5) sales point (1 – 2) primary secondary 1 comfort soft and flexible 4 2 2 allow free movement 5 2 3 good fit on foot 5 2 4 thermal comfortability 4 2 5 light weight 4 2 comparative percentage 24.13% 27.38% 6 performance durable 5 2 7 good adhesion of outsole 5 2 8 not fabric fungi problem 4 1.5 9 not make skin irritation 4 2 10 protection against hazards 4 1.5 11 slip resistance 4 2 12 easy to lock and unlock 5 1 13 easy to don/doff 4 1 14 easy to polish 4 1 comparative percentage 23.77% 21.29% 15 appearance fashionable 5 2 16 good look 5 2 17 nice finish 5 2 18 wide colour range 5 2 comparative percentage 27.42% 27.38% 19 availability wide size range 5 2 20 reasonable price range 4 1.5 comparative percentage 24.68% 23.95% the target value of customer requirements was determined by approximating the digits below 0.5 to the lower full number and higher 0.5 to the next full number with the range from 1 to 5. moreover, the sales point of customer requirements was also determined with the range from 1 to 2. the comparative percentage of the primary customer requirements was also determined among the primary customer requirements as shown in table 2. table 2 shows the results of the target value and sales point of customer requirements that determined by considering the need of customers. this table also shows that the primary customer requirements such as appearance, availability, comfort and performance weighs the percentage target value of 27.42%, 24.68%, 24.13% and 23.77%, respectively. moreover, the primary customer requirements such as appearance, comfort, availability and performance weighs the percentage sales point of 27.38%, 27.38%, 23.95% and 21.29%, respectively. 3.2. determination of technical requirements customer requirements were properly translated into technical requirements through brainstorming and reviewing different literatures of footwear development process (siriphan and nopadon, 2012; suzana et al., 2020; adul and thanin, 2020; lucie et al., 2020; salto, 2016; bitlisli et al., 2013; muhammed et al., 2012). accordingly, three primary and twenty secondary technical requirements were generated. moreover, the average degree of difficulty, target value and technical competitive assessment were determined by approximating the digits below 0.5 to the lower full number and higher 0.5 to the next full number with the hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 33 range from 1 to 5. the comparative percentage of the primary technical requirements was also determined among the primary technical requirements and the competitors as shown in table 3. table 3 shows the technical requirements and the results of the degree of difficulty, target value and technical competitive assessment of footwear that made in ethiopia, china and europe. the degree of difficulty for the primary technical requirement such as manufacturing, materials and design weighs 34.01%, 33.33% and 32.65%, respectively. the target value for the primary technical requirement such as manufacturing, materials and design weighs 34.60%, 33.20% and 32.16%, respectively. in the case of technical competitive assessment, european footwear weighs the highest value for the primary technical requirement such as design, materials and manufacturing with 44.87%, 44.78% and 41.67%, respectively. chinese footwear weighs the intermedium value for the primary technical requirement such as design, materials and manufacturing with 37.18%, 35.82% and 33.33%, respectively. ethiopian footwear weighs the lowest value for the primary technical requirement such as manufacturing, materials and design with 25.00%, 19.40% and 17.95%, respectively. 3.3. development of qfd model qfd model of footwear development process was developed using qfd capture professional edition 4.2.20 based on the results of the customer and technical requirements of the study as discussed in the figures 1 to 4. table 3: technical requirements, degree of difficulty and technical competitive assessment # technical requirements degree of difficulty (1 – 5) target value (1 – 5) technical competitive assessment primary secondary ethiopia (1 – 5) china (1 – 5) europe (1 – 5) 1 design lasting and sewing design 3 4 3 4 5 2 sewing pathway design 4 3 2 3 5 3 locking system design 3 4 3 4 5 4 style and colour design 3 4 2 5 5 5 shape and size design 3 4 2 5 5 6 sole tread design 4 3 1 4 5 7 water and air permeability design 4 4 1 4 5 comparative percentage 32.65% 32.16% 17.95% 37.18% 44.87% 8 materials upper materials 3 4 3 4 5 9 in-sock materials 3 4 2 4 5 10 insole materials 3 4 2 4 5 11 outsole materials 4 3 1 4 5 12 lining materials 4 4 3 4 5 13 adhesive materials 4 4 2 4 5 comparative percentage 33.33% 33.20% 19.40% 35.82% 44.78% 14 manufacturing preparation 3 4 3 4 5 15 coupling and moulding 3 4 3 4 5 16 tacking and trimming 4 4 3 4 5 17 scouring and roughing 4 4 3 4 5 18 ironing and lasting 3 4 3 4 5 19 gluing and attaching 4 4 3 4 5 20 finishing 4 4 3 4 5 comparative percentage 34.01% 34.60% 25.00% 33.33% 41.67% hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 34 figure 1 shows that there was a strong, moderate and weak relationship between the customer and technical requirements. figure 1: qfd results of relationship matrix, where, the (●) symbol stands for strong relationship, the (○) symbol stands for moderate relationship, the (δ) symbol stands for weak relationship and the blank space stands for insignificant relationship between customer and technical requirements. . hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 35 figure 2: qfd results of interrelationship matrix, where, the (+) sign stands for synergetic interrelationship, the (-) sign stands for compromise interrelationship and the blank space stands for insignificant interrelationship between technical requirements. figure 2 shows that there was almost a synergy interrelationship between the technical requirements. figure 3 shows the results of customer competitive assessment. customer requirements (whats) such as good fit on foot, not make skin irritation, fashionable, good look and wide color range weighs the highest percent of importance rate with 6.9%, 6.9%, 6.4%, 6.4% and 6.4%, respectively. hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 36 figure 3: qfd results of customer competitive assessment figure 4 shows the results of technical competitive assessment with maximize direction of improvement. in the case of percent of importance, the technical requirements (hows) such as lasting and sewing design, sewing pathway design, shape and size design, style and color design, and outsole materials weighs the highest rate 9.6%, 9.1%, 8.1%, 7.9% and 7.7%, respectively. hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 37 figure 4: qfd results of technical competitive assessment 4. conclusion this study deals with footwear development process using quality function deployment to meet customer requirement. the findings of this study made it evident that quality function development is a superb technique that can help to deal with every aspect of footwear development process. thus, several customer and technical requirements were generated with regard to footwear development process based on the data collected from the respondents and different literatures. additionally, potential values such as customer competitive assessment, importance to customer, target value, sales point, degree of difficulty and technical competitive assessment were determined. the result of the analysis of the customer and technical requirements show that the footwear that were made in ethiopia had lower value when compared with the value of the footwear that were made in china and europe except in the case of performance and availability. in the case of qfd model, the customer and technical requirements with the higher percentage of importance (6.9% and 9.6%, respectively) demand higher attention in the development process of footwear in comparison with that of the lower percentage of importance (2.3% and 1.6%, respectively). as such, the study shows that ethiopian footwear needs quality improvement in order to satisfy both the customer and technical requirements. as a result, ethiopian footwear manufacturing companies shall strive more in order to cope up with chinese and european footwear manufacturing companies. therefore, the researchers would like to recommend the introduction of quality function deployment, which has been a proven technique for maintaining the quality of footwear development process. hence, concerned stakeholders shall use the prioritized customer and technical requirements in customer oriented footwear development process. acknowledgement the authors would like to thank all the respondents who have participated in informant interview and questionnaire. hailu beyecha et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 38 reference adul a. 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(1990). quality function deployment: integrating customer requirements into product design. cambridge, productivity press. 52 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper morphometric analysis and prioritization of sub-watersheds for soil erosion using geomatics technologies in megech river catchment, lake tana basin, north western ethiopia muralitharan jothimani1,, francis lawrence2, zerihun dawit3 1department of geology, college of natural sciences, arba minch university, arba minch, ethiopia 2department of applied geology, adama science & technology university, adama, ethiopia 3department of geology, college of natural and computational sciences, university of gondar, gondar, ethiopia article info abstract article history: received 27 july 2020 received in revised form 29 september 2020 accepted 10 october 2020 soil erosion is one of the most critical environmental problems in the sustainable development of agriculture and natural resources. ethiopia is facing severe soil erosion problems. the present study was carried out in the megech river catchment, lake tana basin, north western ethiopia. the present study aims to identify the sensitive soil erosion-prone sub-watersheds in the megech river catchment. aster-dem (advanced space-borne thermal emission and reflection), a 30 m spatial resolution digital elevation model (dem), was used to delineate the sub-watersheds and drainage networks through spatial analyst and archydro extension of esri arcgis v10.6.1 software. the cloud-free optical satellite data got from landsat-8 operational land imager (oli) has been used to update the drainage network of the present study area. the study area was divided into four sub-watersheds: ws-1, ws-2, ws-3, and ws-4. the primary, linear, and areal drainage morphometric parameters were calculated by applying the standard formula. furthermore, the ranks were allocated to each drainage morphometric parameter of the four subwatersheds based on their soil erosion proneness. the compound factor value was calculated for the sub-watersheds. the lower value of the compound factor has a high possibility of soil erosion and vice versa. the compound factor of the present study area's sub-watersheds is 2.33 (ws-1), 2.88 (ws-2), 2.11(ws-3), and 2.67 (ws-4). based on the compound factor value, the present study area's sub-watersheds 3,1,4 and 4 were classified into very high, high, medium, and low priority sub-watersheds, respectively. through morphometric drainage analysis, the subwatershed-3 has been identified as a very high-priority ranked watershed in the present study. it needs immediate soil conservation measures for efficient watershed planning and management. further, the present study shows the effectiveness of the drainage morphometric analysis using the satellite image and gis techniques in prioritizing the sub-watersheds for soil resource conservation and management in the megech river catchment, lake tana basin, north western ethiopia. keywords: morphometric analysis soil erosion sub-watershed prioritization geomatics megech river ethiopia 1. introduction in ethiopia, agricultural productivity and food security are facing problems due to land degradation resulting from soil erosion (hurni 1993; hengsdijk et al., 2005; erkossa et al., 2015; taguas et al., 2015;  corresponding author, e-mail: muralitharangeo@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.225 fazzini et al., 2015; keesstra et al., 2016; nigussie et al., 2017; mekuriaw et al., 2018). at present, the northwestern part of ethiopia faces the highest soil erosion problems (hurni et al., 2015). according to (woldeamlak and http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021................ jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 53 stroosnijder, 2003; belay et al., 2014; halefom and teshome, 2019), soil erosion in ethiopia is caused by deforestation and the growth of the urban area and rangeland. this continued soil erosion has led to soil loss, exposure of rock outcrops, soil nutrient depletion, agricultural productivity, and environmental degradation. by organizing the community for agricultural production, food security, population livelihood improvement, and alleviating environmental damage, the ethiopian government facilitates soil conservation techniques and methods. (tesfaye et al., 2014a, 2014b; haregeweyn et al., 2015; kebede, 2014; teshome et al., 2016; kawo and shankar, 2018; athick and shankar, 2019; shankar and kawo, 2019). according to amare et al. (2014) and teshome et al. (2016), the following soil conservation structures, such as stone bunds, soil bunds, and percolation ditches, have been constructed in different parts of ethiopia through community mobilization. poitras et al. (2011) stated that deprived and inadequate data on soil erosion and stream flow lead to unreliable planning and inadequate project operation of soil conservation measures. there is a need for a scientific study to identify the soil erosion-prone area and further identify suitable soil erosion conservation structures. hence, detailed hydrological and soil erosion proneness information is needed for sustainable development in soil conservation management practices of the region of interest. watershed prioritization is a well-known scientific method for identifying soil erosion-prone areas, floodprone areas, and suitable areas for groundwater exploration (vittala et al., 2008; magesh et al., 2011; thomas et al., 2012). it is essential for comprehensive watershed development and improved soil management in arid and semi-arid regions to know the local drainage morphometry and their environmental implications (sreedevi et al., 2009; shankar et al. 2009; gulavani et al., 2017; everard et al., 2018). a drainage basin is an essential landscape of geomorphic and hydrologic structure. it is an elementary unit concerned with collecting the supply of water and sediments. it requires a drainage morphometric analysis for the watershed prioritization process and covers the mathematical quantification of the basin's diverse aspects (clarke, 1966). linear, shape, and relief features comprise numerous parameters like stream number, stream length, drainage density, circularity ratio, form factor, and relief ratio (magesh and chandrasekar, 2014). horton (1945) introduced morphometric quantification first and explained the fundamental relation of drainage arrangements with the basin's hydrology. later, several researchers have contributed to the development of methods of drainage morphometric analysis (strahler 1957; shreve 1966; gregory and walling, 1968; ziemer, 1973; breyer and scott snow, 1992; al-sulaimi et al., 1997; agarwal, 1998; nag and chakraborty, 2003; reddy et al., 2004; das and mukherjee, 2005). in the past, watershed management studies needed the data associated elevation, slope, geology, soil data through topographic maps, and collection of the datasets mentioned above wanted extensive and tedious field surveys (sreedevi et al., 2013). nowadays, advanced remote sensing and gis (geomatics) technologies made watershed management studies relatively easy with high precision. geomatics technologies became a vital component in watershed management research (subyani et al., 2010; sangle and yannawar, 2014; kumar et al., 2018). remote sensing provides high accurate terrain information and gis technologies contributing advanced tools for analyzing the satellite data for the drainage morphometric investigations. remote sensing and gis method-based morphometric studies have been conducted in different parts of the world by the following researchers (al-sulaimi et al., 1997; subyani et al., 2010; sehgal and babar, 2013; aouragh and essahlaoui, 2014; biswas et al., 2014; pophare and balpande, 2014; martins and gadiga, 2015; osano, 2015; kumar and kshitij, 2017; rawat et al., 2017; yanina et al., 2017; kumar et al., 2018; jothimani et al., 2019 & 2020). drainage morphometric studies are critical in hydrological investigations of the watersheds (sreedevi et al., 2009), and it is also essential for the subsequent studies at the watershed level such as estimation of soil erosion proneness and flood susceptibility mapping (bagyaraj and gurugnanam, 2011; altaf et al., 2014; farhan and anaba, 2016; gopinath et al., 2016; masoud 2016; yogesh et al., 2016; kandpal et al., 2017; meshram and sharma, 2017; satheesh kumar and venkateswaran 2018 prabhakar et al., 2019; prakash, 2019), estimation of groundwater potentialities (jasmin and mallikarjuna, 2013), estimation of surface water potential (suresh and jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 54 sudhakar 2004), to determine plant growth potential (kadam et al., 2017), sediment yield (altaf and meraj, 2014), and site selection for groundwater recharge structure and soil protection in the basin (rekha et al., 2011; wani and javed, 2013; choudhari et al., 2018). with this background, the present study was conducted with the following specific objectives: (i) aster dem coupled with gis techniques were used to extract the drainage network, and the cloud-free optical satellite data such as: landsat-8 operational land imager (oli) has been used to update the present's drainage network area. (ii) calculation of the various drainage morphometric parameters using the standard formula of the megech river's sub-watersheds, and (iii) to prioritize sub-watersheds using the compound factor method and rank the sub-watershed for protection, preparation, and administration of the soil resource in the present study area. there have been no such studies using this current method in the present study area, and hence, the current study is the leading of its kind in the present study area. 2. materials and methods 2.1. study area in the present study, drainage morphometric analysis and prioritization has been carried out in the megech river catchment, lake tana basin. the megech river catchment lies between latitudes 12°15′48′′ to 12°45′17′′ n and longitudes 37°21′31′′ to 37°36′56′′ e in northwestern ethiopia is shown in figure 1. the elevation ranges from 1781 to 2896 m above mean sea level. the megech river catchment has a rough terrain with a slope ranging from 0° to 74° (figure 2). it has an area of 560 km2 and forms a part of the lake tana basin, and establishes one of the blue nile river source basins. according to ems (2019), the average maximum temperature ranges between 18.4°c and 29.2°c, and the average minimum temperature is between 8.3°c and 13.1°c. as per the ethiopian standard agro-climate classification system, the megech river catchment falls between dega (cold and humid) and woinedega (cool sub-humid) agro-climatic regions. the land use of the catchment is mostly agricultural, followed by woody and shrub lands. the megech river instigates from the semen mountains and then flows to a southern course and ends into lake tana. it is one of the major rivers flowing into lake tana from the northern part of ethiopia. the upper northern part of the megech river catchment is characterized by a rugged mountainous, whereas the lower part, around lake tana, is characterized by flat low-lying land (wwdse and tahal group, 2008). the study area’s elevation and slope maps were prepared from the aster-dem. figure. 2 show the elevation map of the megech watershed. the megech watershed has a gentle slope to extremely steep slopes and the slope values ranging from 0° to 74°. according to the ethiopian geological survey (gse, 2011), the catchment area comprises upper basaltic lava flows, trachytes with different weathering natures, and lacustrine sediments. according to fao (2006), the main soil types in the present study area are luvisols, regosols, vertisols, fluvisols, and cambisols. 2.2. materials the following datasets/materials have been used in the present study, and the description of the data and its sources have been discussed in the following section. aster (advanced space-borne thermal emission and reflection), 30 m resolution, and tile number (n12°e37o) were downloaded from the following website (https://search.earthdata.nasa.gov/search/). moreover, it is used to delineate the sub-watersheds and drainage networks have done by using spatial analyst and arc hydro extension of esri arcgis v10.6.1. the cloudfree landsat-8, operational land imager (oli) optical satellite data with path-row numbers 170-051, dated 22february-2018, were downloaded from the united states geological survey (usgs) global visualization viewer (glovis) portal (http://earthexplorer.usgs.gov/). furthermore, the same has been used to update the drainage network of the study area. 2.3. extraction of drainage networks and demarcation of sub-watersheds boundaries the extraction of drainage networks and demarcation of the four sub-watersheds boundary were completed with arcmap 10.6.1 coupled with archydro tools using aster (dem). the following dem processing methods (fill sinks, flow direction, flow accumulation, stream definition, stream segmentation, and catchment https://search.earthdata.nasa.gov/ jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 55 grid delineation) were carried out to extract the drainage network and demarcate the sub-watershed’s boundary. the megech river basin is divided into four subwatersheds (ws-1, ws-2, ws-3, and ws-4). the megech river catchment’s drainage network and subwatershed boundaries are shown in figure 3. figure 1: study area map figure 2: elevation and slope map jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 56 figure 3: drainage network and sub-watershed boundary map 3. results and discussions the standard formula was used to calculate the following drainage morphometric parameters viz; area, perimeter, stream order, number of streams, and perimeter. these parameters were grouped into basic drainage morphometric parameters. linear drainage morphometric parameters calculated include stream order (u), stream number (nu), stream length (lu), bifurcation ratio (rb), mean stream length (lsm), and stream length ratio (rl). areal drainage morphometric parameters calculated include drainage density (dd), drainage frequency (fs), circulatory ratio (rc), form factor (ff), elongation ratio (re), and length of overland flow (lg). morphometric parameters and their corresponding standard formulae are shown in table 1. 3.1. linear morphometric parameters the first step in the drainage morphometric characterization of a river catchment is the description of stream order and stream order, as suggested by strahler (1964) used for the present study area. stream order always increases from upstream to downstream, horton (1945). in the present study, fifth-order drainage order (figure 3) attained for morphometric characterization. ws-1 and ws3 exhibit the vth order drainage pattern; ws-2 and ws-4 exhibit ivth order. the study area exhibits the dendric drainage pattern and it is exhibiting the presence of the hard rock in the major part of the study area. the order-wise drainage numbers are shown in table 2. a total of 5076 streams were recognized in the entire megech river catchment. of these, 49.37% (2506) are first-order, 21.45% (1089), second-order, 14.58% (740), third-order, 9.93% (504) fourth-order, and 4.67% (237) contain fifth-order streams. the total length of streams calculated in ws-1 is 247 km, 188 km in ws-2, 232 km in ws-3, and 104 km in ws-4. we give the results of stream orders in (table 2). the mean stream length is a typical property connected to the drainage network and its related surface. the mean stream length (lsm) was calculated by dividing the total stream length (lu) of order ‘u’ by the total number of streams (nu) of order ‘u’. the mean stream length (lsm) calculated is 0.11 for ws-1, 0.15 for ws-2, 0.18 for ws-3, and 0.2 for ws-4. the stream length ratio (rl) was measured as the ratio of the mean stream length of one order to the next lower order of the stream segment. stream length sections of individual of the successive orders of a basin tend to be a direct symmetrical series with stream length increasing towards higher streams (horton, 1945). we give the stream length ratio calculated for each sub-watershed in table 3. the bifurcation ratio (rb) is the ratio of the number of streams of the given order “nu” to the number of streams of higher-order “u+1”. the bifurcation ratio reveals the shape of the basin. an elongated basin is likely to have a high rb, whereas a circular basin is likely to have a low rb (schumm, 1956). thus, from the values of the bifurcation ratio, ws-4 exhibits an elongated shape, whereas sw2 is nearly circular. in the study, each sub-watershed bifurcation ratio was calculated, which varies from 1.83 in ws-1, 1.57 in ws2, 1.98 in ws-3, and 2.65 in ws-4 (table 4). the mean bifurcation ratio (rbm) is defined as the average of the bifurcation ratio of all orders. the basin length is an essential morphometric parameter of the drainage basin. the basin length is maximum in ws-3 and minimum in ws-2. the basin length varies from 24 km in ws-1, 21 km in ws-2, 25 km in ws-3, and 16 km in ws-4 (table 4). jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 57 table 1: morphometric parameters with formulae s.no morphometric parameters formulae/definition references linear morphometric parameters 1 stream order (u) hierarchical rank strahler (1964) 2 stream number (nu) total number of stream segments of the order ‘u’ horton (1945) 3 stream length (lu) the total length of the stream segments of that particular order horton (1945) 4 bifurcation ratio (rb) rb = nu/n(u+1) where nu = total number of stream segments of the order ‘u’ and n(u+1) = number of stream segments of the next higher order schumm (1956) 5 mean bifurcation ratio (rbm) rbm=average of bifurcation ratios of all orders strahler (1957) 6 mean stream length (lsm) lsm = σlu/nu where lu = total length of the stream segments of the particular order nu = total number of stream segments of the same order ‘u’ horton (1932) 7 stream length ratio (rl) rl = lu/l(u−1) where lu = the mean length of all stream segments of a given order (u) and l(u−1) = the mean length of all stream segments of one order less to given order (u) horton (1945) 8 basin length (lb) 1.312*a 0:568 where, l=basin length (km), a=area of the basin (km2) nooka et al. (2005) areal morphometric parameters 9 basin perimeter (p) (km) gis analysis schumm (1956) 10 drainage frequency (df) fs = σnu/a where nu = total number of stream segments of the order ‘u’ and a = area of the watershed (km2) horton (1932) 11 drainage density (dd) dd = σl/a where l = the total length of streams; a = area of the watershed horton (1932) 12 form factor (ff) rf = a/lb 2, where a = area of the basin and lb = (maximum) basin length horton (1932) 13 circulatory ratio (cr) cr = 4πa/p 2 where a = area of the basin (km2) and p = perimeter of basin (km) miller (1953) 14 drainage texture (dt) dt = n1/p where n1 = the total number of first-order streams; p = the perimeter of the watershed) horton (1945) 15 elongation ratio (er) er = 2√(a/π)/lb where a = the area of watershed, π = 3.14, lb = the basin length schumn (1956) 16 compact coefficient (cc) cc = p/2√πa where p = perimeter of basin (km) and a = area of the basin ( km2) horton (1945) 17 length of overland flow (lg) lg = 1/2dd where dd = drainage density of basin or lg = (1/dd)/2 horton (1945) table 2: results of the morphometric analysis of the sub-watersheds sub-ws number of streams of each order (nu) stream length of each order (lu) in km 1st 2nd 3rd 4th 5th 6th total 1st 2nd 3rd 4th 5th 6th total ws-1 896 373 370 121 139 ---1899 114 47 32 12 42 ---247 ws-2 579 273 149 193 -------1194 103 36 28 21 ------188 ws-3 704 310 196 56 98 ---1364 112 52 35 10 23 ---232 ws-4 327 133 25 134 -------619 54 25 8 17 ------104 jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 58 table 3: results of the morphometric analysis of the sub-watersheds sub-ws stream length ratio (rl) mean mean stream length (lsm) mean 2/1 3/2 4/3 5/4 6/5 ws-1 0.41 0.68 0.38 3.5 ---1.24 0.13 0.13 0.09 0.10 0.13 0.30 0.11 ws-2 0.35 0.78 0.75 1.0 ---0.72 0.18 0.13 0.19 0.11 0.18 ----0.15 ws-3 0.46 0.67 0.29 2.3 --3.72 0.16 0.17 0.18 0.18 0.16 0.23 0.18 ws-4 0.46 0.32 2.13 ------2.91 0.17 0.19 0.32 0.13 0.17 ----0.20 table 4: results of the morphometric analysis of the sub-watersheds bifurcation ratio rbm lb sub-watersheds 1/2 2/3 3/4 4/5 5/6 ws-1 2.40 1.01 3.06 0.87 ----1.83 24 ws-2 2.12 1.83 0.77 --------1.57 21 ws-3 2.27 1.58 3.50 0.57 ----1.98 25 ws-4 2.46 5.32 0.19 --------2.65 16 where rbm = mean bifurcation ratio, and lb =length of basin kms 3.2. areal morphometric parameters the calculated basin perimeter varied from 115 km in ws-1, 57 km in ws-2, 109 km in ws-3, and 58 in ws-4 (table 5). the area of the sub-watershed is an additional significant morphometric parameter. in the present study, each sub-watershed area was calculated, which varies from 168 km2 in ws-1, 134 km2 in ws-2, 177 km2 in ws-3, and 80km2 ws-4 given in (table 5). the compactness coefficient calculated for the study area varies from 2.50 in ws-1, 0.72 in ws-2, 0.43 in ws-3, and 0.55 in ws-4 (table 5). the compactness of the coefficient has a direct relationship to the soil erosion proneness. lower values of compactness coefficient signify lesser soil erosion vulnerability risk, while higher values show great soil erosion proneness and represent the need to implement soil conservation measures. high form factor values usually form the watershed's circular shape and have high peak flows over a short period. in contrast, elongated basins with low form factors have low peak flows over long durations. the calculated form factor value varies from 0.16 to 0.22, which shows an elongated circular shape and suggests a flatter peak flow with a longer duration. form factor values are shown in table 5. an elongation ratio calculated varied from 0.61 in ws-1, 0.62 in ws-2, 0.60 in ws-3, and 0.63 in ws-4. an elongation ratio close to 1.0 is typically a region of shallow relief, whereas that of 0.6–0.8 is associated with high relief and steep ground slope (strahler, 1964). the elongation values can be grouped into three categories: >0.9 circular, 0.9–0.8 oval, and <0.7 elongated (strahler, 1964). the elongation ratio values of the study area sub-watershed are <0.7, representing the basin's elongated shape. the elongation ratio values of each sub-watershed are shown in table 8. each subwatershed circulatory ratio was calculated and varied from 0.16 in ws-1, 0.52in ws-2, 0.19 in ws-3, and 0.30 in ws-4 (table 5). a maximum circulatory ratio of 0.52 was observed in ws-2 and represented the circular shape of sub-watershed. table 5: results of the morphometric analysis of the sub-watersheds sub-watersheds a p df dd ff cr dt er cc lg ws-1 168 115 11.30 1.47 0.29 0.16 7.79 0.61 2.50 0.340 ws-2 134 57 8.91 1.40 0.30 0.52 10.16 0.62 1.39 0.357 ws-3 177 109 7.71 1.31 0.28 0.19 6.46 0.60 2.31 0.382 ws-4 80 58 7.74 1.30 0.31 0.30 5.64 0.63 1.83 0.385 a= area, p=perimeter, df = drainage frequency, dd= drainage density, ff= form factor, cr= circulatory ratio, dt= drainage texture, er= elongation ratio, cc= compact coefficient, and lg= length of overland. jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 59 drainage density shows the underlying rock's physical properties of the area. drainage density in the present study area varies from 1.47 km/ km2 in (ws-1) 1.40 km/ km2, in (ws-2) 1.31 km/ km2 in (ws-3) and 1.30 km/ km2 in (ws-4) (table 5). the study area's overall drainage density ranges from 0 km/ km2 to 3.30 km/ km2. permeable subsoil material, thick vegetation, low elevation, and coarse drainage texture indicate low drainage density (nag, 1998). high drainage density is the subsequent impermeable subsurface material, thin vegetation, mountainous relief, and fine drainage texture. in this study, each sub-watershed shows a different stream of frequency value. higher stream frequency values have observed in ws-1 and ws-2, representing impervious sub-surface media, whereas less stream frequency resulted in ws-3 and ws-4 and represented the porous sub-surface media with low elevation. table 5 shows the stream frequency values. 3.3. priority ranking of sub-watersheds the present study emphasizes prioritizing the four sub-watersheds of the megech river based on a drainage morphometric parameter analysis. the following morphometric parameters like drainage density (dd), drainage frequency (df), circulatory ratio (cr), bifurcation ratio (br), elongation ratio (er), drainage texture (dt), form factor (ff), compactness coefficient (cc), and length of overland (lg) were measured and ranked accordingly. morphometric parameters like rb, dd, lg, and df have a direct relationship with soil erosion proneness (biswas et al. 1999; nooka et al. 2005; javed et al. 2011). rank1 was assigned to the highest value of the above-mentioned morphometric parameters, rank 2 to the second-highest value of the morphometric parameters, and rank 3 given the lowest value of the above-mentioned drainage morphometric parameters. the following drainage morphometric parameters, circulatory ratio (rc), form factor (ff), drainage texture (dt), and compactness coefficient (cc) have a reverse relationship with soil erosion proneness as stated by (biswas et al. 1999; nooka et al. 2005; javed et al. 2011). subsequently, rank 1, assigned to the lowest value of the above-mentioned morphometric parameters, the following lower value has been assigned a rank of 2, and rank 3 is assigned to the highest value of the above-mentioned drainage morphometric parameter. thus, the ranks were allocated to each drainage morphometric parameter of the four subwatersheds based on their flood proneness is shown in table 6. the compound factor was calculated by summing the assigned ranks of the various drainage morphometric parameters and dividing them by the number of parameters used to prioritize the sub-watersheds (patel et al., 2012). in the present study, sub-watershed-3 got very highly prioritized with the lowest compound factor value of 2.11. the sub-watershed with the highest compound factor value of 2.88 (ws2) has a low priority rank. the sub-watershed, which has the lowest value of the compound factor, is highly vulnerable to soil erosion. sub-watershed-wise compound factor values and their prioritization rankings are shown in table 7 and figure 4. in this present study, sub-watershed-3 has identified subwatershed-3 as a high-priority ranked watershed, and it needs immediate soil conservation measures for efficient watershed planning and management. table 6: estimation of compound factor values morphometric parameters sub-watersheds ws-1 ws-2 ws-3 ws-4 bifurcation ratio 3 4 2 1 drainage frequency 1 2 3 4 drainage density 1 2 3 4 length of overland flow 4 3 2 1 circulatory ratio 1 4 2 3 form factor 2 3 1 4 elongation ratio 2 3 1 4 drainage texture 3 4 2 1 compactness coefficient 4 1 3 2 compound factor value 2.33 2.88 2.11 2.67 jothimani et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 60 table 7: compound factor value and priority ranking of sub-watersheds sub-watersheds compound factor priority ranking ws-1 2.33 high ws-2 2.88 low ws-3 2.11 very high ws-4 2.67 medium figure 4: sub-watersheds wise prioritization for soil erosion map 4. conclusion the present study shows the effectiveness of the aster dem, landsat-8 oli image, and gis techniques in the quantitative drainage morphometric analysis. therefore, remote sensing data and gis techniques are more efficient for understanding individual subwatershed morphological characteristics. the linear, areal, and relief morphometric aspects established the watershed's hydrologic performance, and it is the same. it is beneficial for the sub-watershed wise prioritization. in the present study, four sub-watersheds were considered for the drainage morphometric analysis. the selected drainage morphometric parameters were calculated using the standard formula. the morphometric parameters such as bifurcation ratio, drainage density, length of overland flow, and drainage frequency are directly connected with soil erosion proneness. hence, rank 1 is assigned to the highest values of the parameters mentioned above, followed by second-rank to second-highest value, and rank third given the above parameters' lowest value. the morphometric parameters such as circulatory ratio, form factor, elongation ratio, and drainage texture and compactness coefficient have a reverse relation with soil erosion proneness. hence, rank 1 is assigned to the lowest values of those parameters, followed by rank two to the second-lowest value, and ranks three, given the above parameters' highest value. thus, the ranks are allocated to each drainage morphometric parameter of the four subwatersheds; then, the compound factor is computed by aggregating the assigned ranks of the criteria mentioned above and then dividing by the number of morphometric criteria used for sub-watersheds prioritization. through the present analysis, sub-watershed-3 has been identified as the very-high soil erosion-prone watershed. furthermore, it needs immediate soil conservation remedial measures for efficient soil resource management planning. the 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(1973). quantitative geomorphology of drainage basins related to fish production. alaska department of fish and game, division of commercial fisheries. https://doi.org/10.1007/s12517-011-0472-7 19 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper extraction and characterization of oil from moringa stenopetala seed as potential industrial source gemechu yadeta forest products innovation research and training center; ethiopian environment and forest research institute, p.o.box: 2322, addis ababa, ethiopia article info abstract article history: received 29august 2021 received in revised form 27 may 2022 accepted 08 june 2022 this study investigated the extraction and characterization of oil from moringa stenopetala seed oil. oil was extracted using soxhlet extraction method at temperatures of 70 0c, 75 0c and 80 0c. the extraction time varied from 3 hours to 5 hours and the sample sieve size varied from 0.75 mm to 1.5 mm. the experimental result showed that the maximum oil yield was obtained at optimum process conditions of; temperature 80 °c, extraction time 5 hours and sample mesh size of 0.75 mm. the highest oil yield obtained was 39.86 %. this result agreed with the average oil content of moringa stenopetala which is 35 % to 45 %. above 5 hours, the extraction was completed and no yield was obtained. decreasing sample size below 0.75 mm led to lower yield. hexane was the solvent used for the extraction. experimental data was analyzed by box behnken design method and the significance of experimental results was determined from analysis of variance (anova). the main physicochemical properties of oil were determined according to international astm and en standards. it was found that pure extracted moringa stenopetala oil has moisture content 6.54 %, ph 6.7, specific gravity 0.84 g/mole, kinematic viscosity 9.4 mm2/s, acid value 1.6 mg koh/g, saponification value 189 mg koh/g, free fatty acid 0.8 % and molecular weight of 895.5 g/mol. these results agreed with international standards values and previous works. keywords: characterization eextraction mmoringa stenopetala seed oil ssoxhlet 1. introduction moringa species are among the high value trees which belong to the family of moringaceae which consists of 13 species. moringa species are highly distributed to southern asia and africa. moringa is a multipurpose tree which is used for medicinal, nutritional, industrial and social values (hamza and azmach, 2017). moringa tree is an evergreen, fast growing, deciduous and widely cultivated tree species. it has some other common english names such as, drumstick tree, horseradish tree and benzoic tree. it grows in tropical and subtropical areas. it requires rainfall about 250-2000 mm depending on soil condition. it grows best in dry sandy soil and tolerates poor soil with ph range 5 corresponding author, e-mail: gemechyade@gmail.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.393 to 9. if water is available for irrigation, moringa trees can be seeded directly and grown anytime during the year. on the other hand, cuttings should be 45 cm to 1.5 m long and 10 cm thick can be planted directly or planted in sacks in the nursery. the tree can reach a height of 10 to12 m and the trunk can reach a diameter of 30 to 45 cm. when matured, each moringa tree can produce a high yield of seed pod from 300 up to 1000 seed pods (azad et al., 2015). in ethiopia, moringa has been promoted for long time. however, its utilization is limited to specific areas. moringa stenopetala is native to ethiopia. it is grown in southern parts of the country and in other areas. moringa http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.393 gemechu yadeta ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 20 is a multipurpose and miracle tree. its leaves are used for medicinal, food, cosmetics production and many other applications. the seed of moringa has high oil yield of 35-45 % (ayerza, 2012). moringa seed oil is not commercially utilized in ethiopia currently however; moringa seed oil is used for energy (biodiesel production), cosmetics, and medicine as food in some areas. even though it has tremendous benefits, moringa is a neglected, miracle and less utilized tree species in ethiopia. moringa particularly moringa stenopetala is an indigenous, neglected, miracle and underutilized tree species in ethiopia. moringa stenopetala has been promoted for long period of time in different parts of the country mainly in drought prone areas. it has a wider adaptability and tolerance to drought and has high oil content. the native moringa species in ethiopia is moringa stenopetala. moringa stenopetala is often referred as african moringa tree because it is native to only ethiopia and northern kenya. moringa stenopetala belongs to the family of moringa cease which is represented by single genus ‘’moringa’’. the genus has 14 species to which moringa stenopetala belongs (mark, 1998). it can grow in elevations between 1000 – 1800 m in ethiopia. it is also extremely a fast-growing tree and can continue growing during the exceptionally long dry season. moringa stenopetala is one of the most widely cultivated indigenous tree species in ethiopia. it is widely distributed in southern parts of ethiopia such as: wolayta, gamo gofa, derashe, konso, sidama, bale, arba minch and borana. although ms is widely cultivated and has got research and development attention worldwide, it has introduced introduce to ethiopia very recently and much more research has to be conducted to evaluate and investigate its species, benefits and biomass production (petr, 2020). there are different seed oil extraction methods. the common oil extraction methods are: mechanical extraction which is used for seeds with high oil yield. its advantage is low operating cost and the absence of solvent separation method (ong, 2013). the other method is enzymatic oil extraction which uses enzymes as to extract oil from crushed seeds. this method is expensive and it takes longer extraction time (atabani, 2013). the modern and current industrial oil extraction method is soxhlet oil extraction method. this method uses solvents such as hexane and petroleum ether. as the solvent evaporates and passes through the sample, the oil is extracted and goes to the flask (nuratiqah, 2015). soxhlet extraction method is selected due to various factors such as soxhlet extraction method results in high oil yield, it is simple and quick, solvent can be reused, and low cost (bhuiya et al., 2016). 2. materials and methods 2.1 sample collection and preparation the sample of moringa stenopetala was collected from arba minch which is located in southern nations, nationalities and peoples of ethiopia. arba minch is located in gamo gofa zone at an elevation of 1285 m and 434.6 km south of addis ababa. it has an average annual temperature of 25 °c and average annual rainfall of 476 mm. the external part of the seed was exposed to remove the kernel from the seed. then, the seed was dried in the sun for three days so that the moisture content was reduced and the minimum value (3.12 %) which is suitable for oil extraction was obtained. the appropriate range of moisture content of feed stock is 0.5 to 10% according to shaha (2011). the dried seed was milled to appropriate size and sieved to less than 1mm mesh size. 2.2 extraction of seed oil 40 g of milled seed sample was placed in 500 ml capacity soxhlet apparatus. 200 ml hexane was used for the extraction of 3 to 5 hours. the extraction was conducted at 70, 75 and 80 °c by varying the extraction time to get the maximum possible oil yield. the oil was extracted for 3 to 5 hours by varying extraction temperatures. the extracted crude oil has unwanted substance such as: hexane, wax, gum and moisture. these substances were removed by evaporation and degumming methods according to akpan et al., (2006). hexane was separated from oil by rotary evaporation at 80 °c. gum and wax were separated from the oil by separatory funnel according to orhevba et al. (2014). gemechu yadeta ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 21 figure 1: sample preparation. figure 1: soxhlet oil extraction. 2.3. purification of the oil the oil yield was calculated from the following equation according to iloamaeke et al. (2016). oil yield (%) = 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑜𝑖𝑙 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑒𝑑 𝑀𝑎𝑠𝑠 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 𝑢𝑠𝑒𝑑 𝑖𝑛 𝑓𝑒𝑒𝑑 *100……(1) 2.4. determination of physicochemical properties of the oil a) determination of moisture content moisture content of the sample was determined according to en 14774-1 standard. b) determination of acid value (a.v) acid value was determined according to en 14104 standard method. 5 g of oil sample was dissolved in 250 mm conical flask with 25 mm ethanol. after adding few drops of phenolphthalein (2 drops) and boiled for few minutes (5 minutes), it was titrated with 0.1 n of koh until the end point of colorless to pink was recognized. the acid value is calculated using the following equation according to iloamaeke et al. (2016). 𝐴. 𝑉 = (𝑉 ∗ 𝑁 ∗ 56.1)/𝑊…………….. (2) where, v is volume expressed in milliliter of 0.1 n ethanol koh solution, n is concentration of ethanol koh solution, w is mass of oil taken in gram. c) determination of specific gravity specific gravity of oil was determined according to en 14214 standard method. gemechu yadeta ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 22 d) determination of kinematic viscosity kinematic viscosity of oil was determined according to astm d445 standard method. e) determination of density density of oil was determined from the following relation: density of oil (ρ) = (specific gravity*density of water) . (3) f) determination of saponification value (s.v) saponification value was determined according to astm d5558 standard method. g) determination of ph standard ph meter was used to determine the ph of the oil h) determination of free fatty acid (ffa) the content of free fatty acid of the oil was determined from acid value using the following equation % ffa = (a.v)/2 …………………….. (4) where, a.v is acidic value of oil i) determination of molecular weight molecular weight of oil was determined according from the following equation according to indhumathi et al. (2014). mwt = 168300/(( s.v-a.v)) ………. (5) where, s.v = saponification value of oil a.v = acid value of oil 2.5. statistical analysis of the experimental results data analysis of this study was carried out by design expert 11.0.0 software using box-behnken standard design method with two factors, three levels and three center points per block to determine the experimental results that maximize extraction of oil. the significance of experimental results was determined from analysis of variance (anova). 3. results and discussions 3.1 yield of oil the maximum oil yield was obtained at 80 °c and 5 hours extraction time and the yield was 39.86 %. this oil yield is in the range of moringa stenopetala oil content (35 – 45%) and it agrees with the range of oil content of moringa stenopetala which was 35% 45 % oil yield according to ayerza (2012). the average oil yield 39.86 % obtained also agreed with 37 % which was reported by orhevba et al. (2013) and 38 % moringa oil yield which was reported by azad et al. (2014). 3.2 physical and chemical properties of oil moisture content the result of moisture was 6.54 %. this result agreed with the previous work of schinas (2008) which was 5 %. higher moisture content forms more soap during transesterification reaction and it is difficult for separation process. moreover, higher moisture of oil decreases the yield of biodiesel produced. ph the ph of oil was determined with ph meter and the result was 6.7. this agreed with the range of msso ph which is 5 – 7. lower ph value makes the oil more acidic which creates corrosion and higher ph value makes the oil more basic and this makes soap during transesterification reaction. formation of more soap on the other hand decreases yield and quality of biodiesel. the result obtained was good since it meets the requirement for production of quality biodiesel and also agreed with the previous report of orhevba et al.(2013) which was 5.9. kinematic viscosity kinematic viscosity of oil was 9.4 mm2. this result agreed with the previous report of mahamudul (2017) which was 9 mm2/s. viscosity o oil affects the storage and handling of fuel oil. highly viscous oil is difficult for pumping and to operate in ci engine. in this study, the result showed that moringa stenopetala oil has lower viscosity and it can be used in ci engines. acid value the acid value of oil was 1.63 mg koh/g oil. this result agreed with literature value. the maximum acid value for alkaline transesterification of oil is two. if acid value is greater than this value, it needs further acid treatment method since it affects the fuel quality of biodiesel produced from it. acid value is the measure of number of carboxylic acid groups such as free fatty acid. saponification value the saponification value of oil was 189.2 mg koh/g oil. higher saponification value of oils is good for production of quality biodiesel. the saponification value of moringa stenopetala oil is 175 -195 mg alcohol/g oil. this result agreed with literature value. gemechu yadeta ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 23 design-expert® software factor coding: actual yield (%) design points 95% ci bands x1 = a: temperature actual factors b: time = 4 c: sieve size = 1.125 a: temperature (°c) 70 72 74 76 78 80 y ie ld ( % ) 15 20 25 30 35 40 45 one factor design-expert® software factor coding: actual yield (%) design points 95% ci bands x1 = a: temperature actual factors b: time = 4 c: sieve size = 1.125 a: temperature (°c) 70 72 74 76 78 80 y ie ld ( % ) 15 20 25 30 35 40 45 one factor table 1: analysis of variance. source sum of squares df mean square f-value p-value model 428.17 3 142.72 55.60 < 0.0001 significant a-temperature 66.59 1 66.59 25.94 0.0003 b-time 353.65 1 353.65 137.76 < 0.0001 c-sieve size 7.94 1 7.94 3.09 0.1064 residual 28.24 11 2.57 lack of fit 27.68 9 3.08 10.98 0.0862 not significant pure error 0.5600 2 0.2800 cor total 456.41 14 factor coding is coded. sum of squares is type iii partial molecular weight the molecular weight of oil was 895.5 g/mol. this result meets the range of molecular mass of vegetable oils (600 -900 g/mol) according to literature value. 3.3. statistical analysis of experimental results analysis of variance (anova) for linear model the significance of the experimental results was determined from analysis of variance. the model f-value of 55.60 implies the model is significant. there is only a 0.01% chance that an f-value this large could occur due to noise. p-values less than 0.0500 indicate model terms are significant. in this case a, b are significant model terms. values greater than 0.1000 indicate the model terms are not significant. if there are many insignificant model terms (not counting those required to support hierarchy), model reduction may improve your model. the lack of fit f-value of 10.98 implies there is 8.62% chance that a lack of fit f-value this large could occur due to noise. lack of fit is bad -we want the model to fit. this relatively low probability (<10%) is troubling. 3.4. the effect of extraction parameters on yield of oil temperature temperature is the main parameter that affects yield of oil extracted. as extraction temperature increased from 70°c to 80 °c, the yield of oil increased and maximum yield (39.86 %) was obtained at optimum temperature of 80 °c. increasing temperature beyond 80 °c led to lower yield and extraction stops finally since the solvent completely evaporates. the boiling point of solvent used (hexane) varies from 70 °c to 80 °c. oil starts to be extracted when hexane starts to boil. fig (1) showed that oil yield increased from 27 % to 39 % as extraction temperature increased from 70 °c to 80 °c. figure 3: effect of extraction temperature on oil yield time as extraction time increases, the oil yield increased and the maximum yield was obtained at optimum time of 5 hours. above 5 hours, the extraction stopped and no oil yield obtained. fig (2) showed that oil yield increased from 26 % to 39.8 % as time increased from 3 hours to 5 hours. this showed that the maximum and optimum oil yield was 3.9.8 %. gemechu yadeta ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 24 design-expert® software factor coding: actual yield (%) design points 95% ci bands x1 = b: time actual factors a: temperature = 75 c: sieve size = 1.125 b: time (hr) 3 3.5 4 4.5 5 y ie ld ( % ) 15 20 25 30 35 40 45 one factor design-expert® software factor coding: actual yield (%) design points 95% ci bands x1 = b: time actual factors a: temperature = 75 c: sieve size = 1.125 b: time (hr) 3 3.5 4 4.5 5 y ie ld ( % ) 15 20 25 30 35 40 45 one factor design-expert® software factor coding: actual yield (%) design points 95% ci bands x1 = c: sieve size actual factors a: temperature = 75 b: time = 4 c: sieve size (mm) 0.75 0.9 1.05 1.2 1.35 1.5 y ie ld ( % ) 15 20 25 30 35 40 45 one factor design-expert® software factor coding: actual yield (%) design points 95% ci bands x1 = c: sieve size actual factors a: temperature = 75 b: time = 4 c: sieve size (mm) 0.75 0.9 1.05 1.2 1.35 1.5 y ie ld ( % ) 15 20 25 30 35 40 45 one factor figure 4: effect of extraction time on yield of oil figure 5: effect of sample sieve size on oil yield sieve size the mesh size of sample is another factor that affected oil yield. high oil yield was obtained from smaller size of sample. fig (3) showed that as the size of sample increased from 0.75 mm to 1.5 mm, the oil yield decreased from 34 to 31 % and optimum yield of oil was obtained at optimum sample size of less than 1mm. this result showed that sieve size of the sample has lower effect on the yield of the sample. in this study, the sample sizes used are close to each other and this made the effect very lower. 4. conclusion in this research oil was extracted from moringa stenopetala seed by soxhlet extraction method. the statistical analysis of experimental results and experimental design was done using design expert 11.0 software. the physicochemical properties of oil were determined according to international standard methods and all the results obtained meet these standards. the experimental result showed that the highest yield of oil was 39.86 % and this value was obtained at optimum value of temperature 8°c and extraction time of 5 hours. the statistical analysis done by box-behnken method showed that increasing extraction temperature and time up to the optimum point increased the yield of oil. however, further increase of the parameters above the optimum point decreased the yield. generally, it can be concluded that moringa stenopetala is a promising alternative feed stock for oil extraction which has a wide industrial and social applications. moringa stenopetala has good oil content and can be harvested throughout the year. the oil extracted meet the standard oil quality and international standard specifications. the novel finding of this research is the new discovered moringa stenopetala seed feed stock for multipurpose oil extraction. acknowledgment i, gemechu yadeta shage is thankful to addis ababa institute of technology, addis ababa university, ethiopian environment and forest research institute, college of natural and computational science, addis ababa university and ethiopian geological survey for their technical support provided. gemechu yadeta ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 25 reference akpan, u.g., jimoh, a., and mohammed, a.d. 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(2014). extraction and characterization of moringa seed oil. journal of food and dairy technology. petr, n., moana, u., shiferaw alem ., and jaromir, n. (2020). biomass production of a young plantation moringa stenopetala and moringa olifera in southern ethiopia. south african journal of botany, 129: 463 470. shaha, a.k. (2011). combustion engineering and fuel technology, oxford & ibh publishing company. schnas, p. (2008). pumpkin seed oil as an alternative feed stock for biodiese production. 13 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (2), 2018 mathematical modeling and analysis of corruption dynamics legesse lemecha* and shiferaw feyissa adama science and technology university, school of applied natural science, applied mathematics program, p. o. box 1888, adama, ethiopia. * corresponding author, e-mail: legesse.lemecha@astu.edu.et abstract we propose a mathematical model for corruption by considering awareness created by anti-corruption and counseling in jail. the model is proved to be both epidemiologically and mathematically well posed. we showed that all solutions of the model are positive and bounded with initial conditions in a certain meaningful set. the existence of unique corruption free and endemic equilibrium points are investigated and the basic reproduction number is computed. then, we study the local asymptotic stability of these equilibrium points. the analysis shows that the system has a locally asymptotically stable corruption-free equilibrium point when the reproduction number is less than one and locally asymptotically stable endemic equilibrium point when the reproduction number is greater than one. the simulation result shows the agreement with the analytical results. keywords: mathematical model, corruption, basic reproduction number, stability 1. introduction the world bank (1997) defined corruption as the abuse of public office for private gain. in this sense, corrupt practices includes: bribery, extortion, fraud, embezzlement, nepotism, cronyism, appropriation of public institutions assets and properties for private use, and influence peddling. it is a symptom and result of institutional weakness, having negative effects on the economic performance of a country (bardhan, 1997). corruption is a complex and multifaceted phenomenon (aidt, 2003) associated with all forms of human organization. as cited in grass et al. (2008), the world bank estimated the annual cost of corruption over us $80 billion worldwide which is more than the total of all economic assistance for development. corruption distorts the rule of law and weakens the institutional foundations on which economic growth depends (world bank, 2014) and thus identified among the greatest obstacles to economic and social development. corruption degrades national security, economic prosperity and international reputation. it is the deep rooted cause of instability and conflict as witnessed in the present situation in ethiopia. corruption could be characterized as mailto:legesse.lemecha@astu.edu.et legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 14 © adama science & technology university https://ejssd.astu.edu.et a “disease” inherent to public power and an indication of bad go ve r na nc e (tiihonen, 2003). however, as reported in blanchard et al. (2005), the features of corruption propagation differs from classical epidemic processes due to its dependence on the threshold value of the local transition probabilities and the mean field dependence of the corruption process. by this we mean that a noncorrupt individual gets infected with high probability if the number of corrupt individuals in the social neighborhood exceeds a certain threshold value whereas in the case of mean field dependence an individual can get corrupt because there is a high prevalence in the society even in the absence of corruption in the local neighborhood. in contrast to the high prevalence of corruption worldwide and large literature on political, social and economic aspects of corruption there is only a small number of attempts to model the dynamics of corruption in a mathematically quantified way. the first mathematical model dedicated to corrupt structures was appeared in (rose-ackerman, 1975) and become active research area since then. several literatures showed that corruption smothering economic development across vast stretches of the globe, notably in africa and asia countries. for example, see in (tanzi, 1998, le van & maurel, 2006, grass et al., 2008) and reference cited therein. it impacts negatively on a variety of economic and social wellbeing of the society and thus described as a worm within the body of the society and a cancer to economic, social, and political development (abdulrahman, 2014; tanzi, 1998; sayaji, 2013; eguda et al., 2017). corruption is an unavoidable part of human social interaction, prevalent in every society at any time since the very beginning of human history till today. it cannot be measured directly due to its elusive nature and the difficulty of separating the control of corruption from corruption itself. the epidemiological corruption modeling approach was reported by many authors including (starkermann, 1989; le van & maurel, 2006; becker et al., 2008; brianzoni et al., 2011; sayaji, 2013; abdulrahman, 2014). the authors studied the effects of corruption on national development by modeling corruption as diseases. in particular, hathroubi (2013) investigated an epidemiological corruption threshold based on the approximation of honest population by dividing the total population n(t) into three compartments susceptible s(t), corrupt c(t), and honest h(t) individual without giving stability analysis of the equilibrium points. however, the author didn't considered well the case of losing immunity of jailed corrupts. the objective of this work is to describe the transmission process of corruption, which can be defined generally as follows: when a reasonable amount of corrupted individuals are introduced into a susceptible population, the corruption is passed to other individuals through its modes of transmission, thus, spreading in the population. corruption is assumed to be legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 15 © adama science & technology university https://ejssd.astu.edu.et a nonstandard epidemic process that rarely emerges out of nothing but is usually related to some already corrupt environment which may affect susceptible populations. thus, in this article we will present a model for the spread of corruption in the spirit of epidemiology which describes the dynamical behavior of corruption, as a disease incorporating losing immunity of jailed and effort rate against corruption. the article is structured as follows. in section 2, we formulate our mathematical model for corruption transmission dynamics. we analyze the positivity and boundedness of solutions as well as the existence and local stability of the corruption-free and endemic equilibria in section 3. section 4 is devoted to numerical simulation. finally, conclusions are given in section 5. 2. model formulation in this section, we consider a scjh (susceptible-corrupt-jailed-honest) type mathematical model for the dynamics of corruption. the total population n(t) is divided into four compartments: susceptible s(t), corrupt c(t), in council through jail j(t) and honesty h(t) at time t ≥ 0 as given in abdulrahman (2014). in this paper, we meant by a susceptible individual that have never engaged in any corrupt practice or those jailed and then released after taking council. a corrupt is one that have engaged in a corruption practice and capable of influencing a susceptible individual to become corrupt. a jailed corrupt is one that is found to be guilty corrupt by law and an honest individual is one that can never be corrupt under any situation. we assume that there is a positive recruitment  into the susceptible class and a positive natural death rate  for all time under the study. susceptible individuals can become corrupt at rate 𝛽 𝐶(𝑡) 𝜃+𝐶(𝑡) through contact with corrupt individuals which are depending on time. it can be increased or decreased based on the magnitude of 𝜃 and 𝐶(𝑡). the remaining model parameters are also defined as follows:  is the effort rate against corruption, p is the corruption transmission probability per contact,  is the maximum saturation constant of the corrupt population in the society, 𝛽 = 𝑝(1 − 𝜏) is the effective corruption contact rate,  is the rate at which corrupt individuals are caught and imprison, 1 𝛾 is the average period jailed individuals spent in prison,  is the proportion of individuals that leaves s, c and j to h compartment due to awareness created by anti-corruption agency through mass media, and counseling in jail respectively on the impact of corruption. it is assumed that the impact of awareness is same. the model also depends on the following assumptions: an individual can be corrupted only through contacts with corrupted individuals, a susceptible, corrupt, and jailed individual can be converted to honest due to awareness created by anti-corruption or counseling in jail. compared to the work of abdulrahman (2014), an individual who legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 16 © adama science & technology university https://ejssd.astu.edu.et lose immunity gained through council in jail do not directly joined corrupt class rather susceptible with the rate of 𝛾(1 − 𝛼) because of human behavior. further, our model takes into consideration the impact due to awareness created by anticorruption. the model prosed in anthithan et al. (2018) do not consider the jailed class which makes differ from our model. figure 1. schematic diagram for corruption dynamics. these assumptions are translated to the following mathematical model: 𝑑𝑆 𝑑𝑡 = 𝐴 − 𝛽𝐶 𝜃+𝐶 𝑆 − (𝛼 + 𝜇)𝑆 + 𝛾(1 − 𝛼)𝐽 𝑑𝐶 𝑑𝑡 = 𝐴 − 𝛽𝐶 𝜃+𝐶 𝑆 − (𝛿 + 𝛼 + 𝜇)𝐶 (2.1) 𝑑𝐽 𝑑𝑡 = 𝛿𝐶 − (𝛾 + 𝜇)𝐽 𝑑𝐻 𝑑𝑡 = 𝛼(𝑆 + 𝐶 + 𝛾𝐽) − 𝜇𝐻. the model involves human population and hence all the parameters used are positive. further, we assume that the initial conditions 𝑆(0) ≥ 0, 𝐶(0) ≥ 0, 𝐽(0) ≥ 0, 𝐻(0) ≥ 0 (2.2) of the governing equations are nonnegative throughout this paper. 3. model analysis in this section, we study the solution of (2.1) in the epidemiologically feasible region. ω = {(𝑆, 𝐶, 𝐽, 𝐻) ∈ 4  : 0 ≤ 𝑆(𝑡) + 𝐶(𝑡) + 𝐽(𝑡) + 𝐻(𝑡) ≤ 𝛬 𝜇 }. 3.1 positivity and boundedness of solutions now we study the positivity and boundedness of the solution of the governing system (2.1). proposition 1. assume that the initial conditions (2.2) hold in 4  . the the solutions {𝑆(𝑡), 𝐶(𝑡), 𝐽(𝑡), 𝐻(𝑡)} of the legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 17 © adama science & technology university https://ejssd.astu.edu.et model equations are also non-negative for all 𝑡 ≥ 0. proof. assume that all the state variables are continuous. then, from the system of equations (2.1) one can easily obtained that: 𝑑𝑆 𝑑𝑡 ≥ − 𝛽𝐶 𝜃+𝐶 𝑆 − (𝛼 + 𝜇)𝑆; 𝑑𝐶 𝑑𝑡 ≥ −(𝛿 + 𝛼 + 𝜇)𝐶; 𝑑𝐽 𝑑𝑡 ≥ −(𝛾 + 𝜇)𝐽; 𝑑𝐻 𝑑𝑡 ≥ −𝜇𝐻. solving these system of differential equations yields 𝑆(𝑡) ≥ 𝑆(0)𝑒 (∫( 𝛽𝐶 𝜃+𝐶 −(𝛼+𝜇))𝑑𝑡) ≥ 0; 𝐶(𝑡) ≥ 𝐶(0)𝑒 (−(𝛿+𝛼+𝜇)𝑡) ≥ 0; 𝐽(𝑡) ≥ 𝐽(0)𝑒 (−(𝛾+𝜇)𝑡) ≥ 0; 𝐻(𝑡) ≥ 𝐻(0)𝑒 (−(𝜇)𝑡) ≥ 0. thus, we can conclude that all the solutions are non-negative in 4  for all 𝑡 ≥ 0. the next proposition shows that it is sufficient to study the dynamics of corruption by model equations (2.1) in a region ω. proposition 2. assume that all the initial conditions are non-negative in 4  for the system ω = {(𝑆, 𝐶, 𝐽, 𝐻) ∈ 4  : 0 ≤ 𝑆(𝑡) + 𝐶(𝑡) + 𝐽(𝑡) + 𝐻(𝑡) ≤ 𝛬 𝜇 }. if 𝑁(0) ≤ 𝛬 𝜇 , then the region 𝛺 is positively invariant. proof. note that all the state variables 𝑆, 𝐶, 𝐽, 𝐻 ∈ 𝐶(  ,  ) and the total population 𝑁(𝑡) = 𝑆(𝑡) + 𝐶(𝑡) + 𝐽(𝑡) + 𝐻(𝑡). from this, we can easily deduce that 𝑑𝑁(𝑡) 𝑑𝑡 = 𝛬 − 𝜇𝑁(𝑡). using the assumption that 𝑁(0) ≤ 𝛬 𝜇 and by integration we can have that 𝑁(𝑡) ≤ 𝛬 𝜇 that is, 𝑁(𝑡) is for all bounded 𝑡 ≥ 0. this implies all the solutions of the model equation (2.1) with initial condition in ω remains in ω. this complete the proof. remark 1 in the region ω, the proposed mathematical model is mathematically and epidemiologically well posed. 3.2 stability analysis the corruption free equilibrium point (cfe) of the system (2.1) is given by �̅� = (𝑆̅, 𝐶̅, 𝐽,̅ �̅�) = ( 𝛬 𝛼+𝜇 , 0, 0, 𝛼𝛬 (𝛼+𝜇)𝜇 ) (3.1) following the approach of abdulrahman (2014), eguda (2017) & anthithan.et al. (2018), we compute the basic reproduction number r0. in the present work, the basic reproductive number is the expected number of new corrupts from one corrupt individual in a fully susceptible population through contact period. now we have the following proposition. legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 18 © adama science & technology university https://ejssd.astu.edu.et proposition 3. the basic reproduction number of the mathematical model (2.1) is given by 𝑅𝑜 = 𝛽𝛬 (𝛼+𝜇)(𝛿+𝛼+𝜇)𝜃 (3.2) proof. let the matrix with the (i, j) entry denotes the number of new corrupts at stage j caused by contacts with corrupt individuals in stage i and the transition matrix 𝑉 with (i, j) entry denotes the rate individuals in stage j progress to stage i. from model (2.1) we have (𝑆 ′(𝑡), 𝐶′(𝑡), 𝐽′(𝑡), 𝐻′(𝑡)) 𝑇 = − 𝑽 such that = ( 𝛽𝐶 𝛼+𝐶 𝑆 0 ) and = ( 𝛼𝐶 −𝛿𝐶 + 𝑏𝐽 ) . where , .a b         the jacobian matrices of and v at equilibrium point are given by 0 0 0 s f              and 0 . a v b        hence the basic reproduction number 1 0 r ( ) . ( )( ) fv                this concludes the proof. theorem 4. (stability of the cfe) the corruption-free equilibrium e of the dynamical system is a) locally asymptotically stable if ( )a      and unstable otherwise, b) neutral if ( ) .a      proof. the characteristic polynomial of the corresponding linearized system of the governing equation is 4 ( ) det(( ) ).p f v i    that is, (1 ) 0 ( ) 0 0 0 0 ( ) 0 0 0 b a b                                 evaluating the roots of this characteristic polynomial, we have , , or . ( ) b b or a                  as the model deals with human population, we assumed all the model parameters are non-negative. consequently, it is straightforward that the corruption-free equilibrium e is asymptotically stable for b   with legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 19 © adama science & technology university https://ejssd.astu.edu.et multiplicity two or .   on the other hand, the cfe e is locally asymptotically stable only if 0 ( ) a         or equivalently, ( ) .a      trivially, a neutral case occurred if ( )a      and it becomes inconclusive. with this we complete the proof of the theorem. in the following theorem we shall investigate the existence of corruption endemic equilibrium point and its stability based on the computed reproduction number. theorem 5. if 0r 1 , then the i. model (2.1) has a corruption endemic equilibrium point given by ( , , , )e s c j h (3.3) where 2 ( )( ( ) ( ( 1) ) ) ; 3 2 2 ( 2 ) ( ( 2 ) ( ) ) ( ( 1) ) s                                                              ( ( )( ) )( ) ; 3 2 2 ( 2 ) ( ( 2 ) ( ) ) ( ( 1) ) c                                                     ; 3 2 2 ( 2 ) ( ( 2 ) ( ) ) ( ( 1) ) ( ( )( ) ) j                                                   2 2 2 (( ) (( ) ( ) ( )) ((1 ) ) ) 3 2 ( ( 2 ) ((2 ) ( )( )) ((1 ) )) .h                                                                          ii. corruption endemic equilibrium is locally asymptotically stable. proof. we set the left hand side of equation (2.1) equal to zero and solve it to obtain the equilibrium (3.3). from the effective corruption induced rate 𝛽𝐶(𝑡) 𝜃+𝐶(𝑡) at equilibrium we have 𝛽�̃� 𝜃+�̃� = − (𝛾+𝜇)((𝜇+𝛼)(𝜇+𝛿+𝛼)𝜃−∧𝛽) (𝜇2+(𝛾+𝛼+𝛿)𝜇+𝛼𝛾(1+𝛿))𝜃+∧(𝛾+𝜇) . this is equivalent to 𝛽�̃� 𝜃+�̃� = (𝛾+𝜇)(𝜇+𝛼)(𝜇+𝛿+𝛼)𝜃( 𝛽∧ (𝜇+𝛼)(𝜇+𝛿+𝛼)𝜃 −1) (𝜇2+(𝛾+𝛼+𝛿)𝜇+𝛼𝛾(1+𝛿))𝜃+∧(𝛾+𝜇) . by proposition 3 r0 = 𝛽∧ (𝛼+𝜇)(𝛿+𝛼+𝜇)𝜃 and note that all parameters are positive. hence, if r0 > 1, then 𝛽�̃� 𝜃+�̃� > 0. this infer the existence of corruption in the specified population. with this we can conclude the existence of corruption endemic equilibrium point. to prove (ii) legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 20 © adama science & technology university https://ejssd.astu.edu.et we compute the jacobian matrix of the system (2.1) at corruption endemic equilibrium �̃� and then evaluate the eigenvalues as given in theorem 3. finally, we employ routh-hurwitz’s criterion (olsder & woude, 2005) to show the corruption endemic equilibrium �̃� of the system (2.1) is locally asymptotically stable for r0 > 1. with this we conclude the proof of the theorem. in the following section we detailed the solution of the proposed mathematical model through numerical simulation and compare its properties with analytical results. 4. numerical simulation this section presents and discusses numerical results for the system (2.1) for different values of parameters given in the model. the simulation process is carried out using matlab and maple for symbolic computations. we start by defining the value of each parameters used in the model developed. then we illustrate the simulation results graphically. 4. 1 parameter estimations the values of parameters given in table 1 are borrowed from abdulrahaman (2014) and ticpi (2017). the remaining parameters values are also carefully estimated and used in the simulation process. the assumed total population and recruitment rate is related by ∧= 𝜇𝑁. table 1: values of parameter used in the numerical simulation. parameter description value reference ∧ recruitment rate 𝜇𝑁 to be computed 𝒑 corruption transmission probability per contact 0.036 abdulrahaman,s. (2014) 𝜷 effective corruption contact rate 0.0234 computed using ticpi, (2017) 𝝉 effort rate against corruption 0.3500 ticpi, (2017) for ethiopia 𝜹 rate at which corrupt individuals are caught 0.0007 abdulrahaman,s. (2014) 𝜽 maximum saturation of corrupters population 100,000 assumed 𝜸 average rate of jailed individuals spent in prison 0.125 abdulrahaman,s. (2014) 𝝁 natural death rate 0.0160 who (2017) for ethiopia 𝜶 proportion of individuals that joins h from each compartment due awareness 0.03 assumed legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 21 © adama science & technology university https://ejssd.astu.edu.et 4.2 simulation results the dynamics of corruption can be studied through numerical simulations by estimating the values of parameters in the model formulated with appropriate initial conditions. the population size is assumed to be n = 700,000 which is equivalent to the population size of medium city. if the total population n = 700, 000, then  = 11,182.108. the corruption-free equilibrium state is given by �̅� = ( 𝛬 𝛼+𝜇 , 0, 0, 𝛼𝛬 (𝛼+𝜇)𝜇 ) = (243224.4615, 0, 0, 456775.5389) and the reproduction numberr0 = 0.6097. figure 2 depicts that the susceptible population decreases asymptotically to the corruption-free equilibrium state while the honest population asymptotically increase to corruption-free equilibrium point. figure 2. susceptible and honest population approaches asymptotically to corruptionfree equilibrium state when r0 < 1. thus we can observe that an agreement between the numerical simulation of the model (2.1) and the analysis of the local stability of the corruption-free �̅� presented in section (3). the corruption endemic equilibrium point is (228590.5911,14602.76181, 72.50912434, 456734.1384)e  for the parameter values given in table 1. the basic reproduction number in this case is r0 = 1.22 which is greater than one. figure 3 clearly shows that all the state variables asymptotically approach to the corruption endemic equilibrium point whenever r0 > 1. further, the corrupt population increases while the susceptible decrease to ward equilibrium point. this means, the susceptible legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 22 © adama science & technology university https://ejssd.astu.edu.et populations become influenced by corrupt individuals and the size of corrupt population raise in the society. also, the population of honest is significantly increasing due to awareness by anti-corruption and counseling in jail. figure 3. all the state variables approach asymptotically to corruption endemic equilibrium point when r0 > 1. as it can be seen in the figure 3, the jailed population is slowly growing. this may be due to highly secretive nature of corruption and the corruptors are remaining in the community without arrested. for this reason, the number of susceptible individuals becomes decreases to the equilibrium which need optimal strategy to interfere. this part is left for future work. by its nature corruption is secretive and its level of prevalence in the population is not uniform. thus, the dynamics of corruption for two countries namely, ethiopia and new zealand are comparatively studied based on transparency international corruption perception index (ticpi, 2017) using the model developed. ticpi use a scale of 0 to 100 where 0 is highly corrupt and 100 is very clean. in this context, new zealand rocked highest clean with score of 89 and somalia is the most corrupt country with score 9. ethiopia scored 35 and ranked 108 out of 180 countries. the penalties for corruption vary from country legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 23 © adama science & technology university https://ejssd.astu.edu.et to country. in some country it ranges from one year to life imprisonment and loss of public office in addition to repaying the amount involved or confiscating property which is gained as a result of corruption. the average period corrupt individuals spent in prison 1/ᵧ is eight (8) years as cited in abdulrahaman (2014). the corruption endemic is almost similar between 0 and 60 simulation time as illustrated in figure 4. beyond t = 60, the endemic is stronger in the case ethiopia. this is due to the difference in corruption resistance in the two countries and thus, the proposed model well predicts the difference of corruption dynamics in the two countries. figure 4. comparison of corruption endemic in the case of ethiopia and new zealand based on ticpi (2017). 5. conclusions corruption challenges good governance and become a hinder for investment. in this paper, we developed and analyzed a mathematical model to study the dynamical nature of corruption based on the governing mathematical model with constant recruitment rate from the total population. the domain in which the model is mathematically and epidemiologically well posed was determined. then the next generation matrix was used to derive the basic reproduction number. the corruption-free equilibrium of the model was proved to be locally asymptotically stable whenever reproduction number is less than one. it is also showed that the corruption epidemic equilibrium is locally asymptotically stable provided that the basic reproduction number is greater than one. finally, the analytical result was verified using numerical simulations. designing optimal control strategy is left for future work. legesse lemecha & shiferaw feyissa ejssd, v 5 (2), 2018 24 © adama science & technology university https://ejssd.astu.edu.et acknowledgments the authors would like to thank adama science and technology university for financial support during this research work. references abdulrahman, s. 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(2013). mathematical modelling: a comparatively mathematical study model base between corruption and development. iosr journal of mathematics, 6, 54-62. waykar s.r., (2013). mathematical modelling: a comparatively mathematical study model base between corruption and development. iosr journal of mathematics, 6, 54-62. world bank (1997). helping countries combat corruption. the role of the world bank. monograph, 8-9. world bank (2014). fraud and corruption awareness handbook. a handbook for civil servants involved in public procurement. http://www.transparency.org/ 26 13 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (1), 2021 journal home page: www.ejssd.astu.edu.et astu research paper the value of virginity, prevalence of premarital sex, and vulnerability to reproductive health risks among young people in wolaita sodo town bewunetu zewude  , tewodros habtegiorgis department of sociology, wolaita sodo university, p. o. box 138, wolaita sodo, ethiopia article info abstract article history: received 13 january 2020 received in revised form 29 june 2020 accepted 17 september 2020 this research investigates the value of virginity, prevalence of premarital sexual practices, and vulnerability to reproductive health risks among the youth in wolaita sodo town. youth learning both in the primary schools (382) and higher education institution (384) were selected using probability proportionate to size sampling technique. institutional-based descriptive and explanatory research designs were used in the study. using a survey method, quantitative data were collected by structured questionnaire. both descriptive and inferential statistical methods were used to analyze and present data. young people in wolaita sodo town were found to have a high value to virginity. it is also found that 18.2% of primary school students reported that they engaged in premarital sexual practice which is lower than the rate found among the university students (33.2%). out of the respondents who reported to have had premarital sex, 38% of primary school students and 59.8% of university students disclosed that they have sexual relationships only with a single partner whereas 20% of primary school students and 19.5% of university students reported that they have five and above life-time sex partners. in addition, primary school students have been found to be better in terms of engaging in less risky premarital sexual practices compared to their university students counterparts (59.8% to 62% in regular condom use; 56% to 55.2% in undertaking hiv testing before engaging in sexual practices, respectively). while being female (r=.181, p<.01), never married (r=.174, p<0.01), and coming from an urban area (r=187, p<0.01) are positively associated to value of virginity, being female is negatively associated to premarital sexual experience (r=-.429, p<0.01). with relatively low level of premarital sexual practices, regular condom use, and better experience of undergoing voluntary hiv testing before sexual intercourse, youth in wolaita sodo town are less vulnerable to reproductive health risks. but, the finding regarding the presence of more than one life-time sexual partners among the respondents may enhance their vulnerability to various reproductive health risks. keywords: premarital sex reproductive health virginity value vulnerability youth 1. introduction young people are highly affected by sexual related problems and exposed to early onset of sexual practices (laumann, 2006). some youth may engage in premarital sexual practices with many sexual partners. therefore, they may have high number of lifetime sexual partners that could be liable to acquire sexually transmitted infections (stis) including human immunodeficiency  corresponding author, e-mail: bewunetuzewude@gmail.com https://doi.org/10.20372/ejssdastu:v8.i1.2021.271 virus (hiv) (vos, 2004). in every society, the first time a young person has sex with a partner is seen as a major social and sexual transition constituting part of the irreversible journey from childhood to adult life (muuss, 1970). virginity loss is defined as the first time a man or woman engages in vaginal-penile intercourse (jessor and jessor, 1975). http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021................ bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 14 according to goody (1976), restrictiveness is a way of avoiding inappropriate marriages: by controlling a girl's sexuality, her family can better control her marriage choice since the loss of virginity may diminish a girl's honor and reduce her marriage chances. virginity is valued in those societies in which young men may seek to better their chances in life by allying themselves through marriage to a wealthy or powerful family. in preserving a daughter's virginity, a family is protecting her from seduction, impregnation, and paternity claims on her child. this is most critical when certain kinds of property transactions are involved. in societies in which dowry is given or daughters inherit properties; it would be attractive to seduce a dowered daughter or heiress, demanding her as wife along with her property (schlegel, 1991). feminization of sexuality means young people’s choices regarding sexual activities are influenced by cultural constructs of masculinity and femininity located in gendered power relations. girls bear more responsibility for premarital virginity loss (matswetu and bhana, 2018). patriarchal values produce sexual double standards whereby virginity has greater significance for females compared to males (palit and allen, 2016). as a result, unmarried young men have the freedom to engage in sexual liaisons without any adverse repercussion on their social standing; virginity is thus an element of normative patriarchal restrictions on women’s sexuality (bhana, 2018). carpenter (2002) argued that the relationship between gender and virginity loss is complex and that the importance of gender as a determinant of sexual meanings and experiences may be diminishing. some researchers (e.g. brumberg, 1997; rubin, 1990) found that a growing number of young women perceive virginity as neither desirable nor undesirable, and a minority of women even approaching virginity loss with eagerness and curiosity, expressing desire to “get it over with,” or seeing virginity as embarrassing or constraining. the decline in abstinence, sexual freedom, laxity and promiscuity, unprotected sex, limited use of contraceptives, female child marriage, female child rape and violence account for the high rate of teenage pregnancy in africa (nnazor and robinson, 2016). previous studies (e.g. geremew kindie et al., 2017; tomas benti et al., 2015; bayisa abdissa et al., 2017; addisu shunu and abdulbasit musa, 2014; daba bane, 2006; netsanet habte et al., 2018) undertaken in ethiopia regarding youth sexual behavior revealed the high prevalence of premarital sexual practices in various areas of ethiopia. being male, having pocket money, failure to discuss sexual issues with intimate friends, and peer pressure were found to be associated factors for the prevalence of premarital sexual practices among adolescent students (geremew kindie et al., 2017). tomas benti et al. (2014) found alcohol use, educational level, and discussion about sexuality to be the factors significantly associated to premarital sexual intercourse among undergraduate students of madawalabu university. another study conducted on out-school youth in yabello town of southern ethiopia by addisu shunu and abdulbasit musa (2014) found being employed and having sexually experienced peers to contribute to the start of premarital sex. mitike yemane and lindtjorn (2008) found that youth who did not believe in the traditional value of preserving virginity until marriage were twice as likely to initiate sex before marriage. in addition, those in older age group, khat chewers, alcohol drinkers, and those who have completed primary education and above were more likely to have premarital sex. premarital sexual practice among high school students was strongly associated with being lower age groups and having boy/girlfriends (netsanet habte et al., 2018). the issue of virginity value among ethiopian youth in general and students learning in various hierarchies in particular, however, has not been adequately addressed by previous studies. mitike yemane and lindtjorn (2008) found that maintaining virginity is still a way of securing marriage for girls living in rural areas of ethiopia. having undertaken the research in nine rural and one urban area, the authors also found that rural youth were three times more likely to believe in the traditional norm of remaining virgin until marriage, as far as comparison of urban and rural youth is concerned. a related study by meles yohannes et al. (2016), on the other hand, found poor value of virginity and high prevalence of early sexual practices among youth in mekelle town, ethiopia. on top of such contradicting findings about the subject, other published studies can hardly be found in ethiopia regarding youth virginity value and its relationship to both prevalence of premarital sexual bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 15 intercourse and exposure of youth to various sexually transmitted infections. the present research, therefore, aimed at assessing young peoples’ value toward virginity, their engagements in premarital sexual practices, and vulnerability to reproductive health risks in wolaita sodo town. it is also important to compare virginity values between youth learning in various levels of schools, especially between those learning at the elementary and university levels. such analysis helps to empirically test whether virginity value among youth declines as their academic level increases. furthermore, it is commonly assumed that university students are more prone to engage in premarital sex than elementary students due to lenient parental control and absence of close supervision. 2. materials and methods 2.1. research design institutional-based descriptive and explanatory research designs were used in the study. the research involved the collection of quantitative data to find out the extent of virginity values, the prevalence of premarital sexual practices, and factors associated to virginity values among the students. survey research method was used to collect quantitative data regarding virginity values, the magnitude of premarital sexual practices, and vulnerability of respondents to various reproductive health risks. 2.2. research design the study was carried out in wolaita sodo town, southern ethiopia. the source population was young people learning at various levels of education in ethiopia during the time of the survey. youth who were learning both at the primary schools of wolaita sodo town and similar survey population attending undergraduate courses at a higher education institution in the area, particularly wolaita sodo university, were considered in the current study. from the primary schools (grade 1-8) available in the town during the time of survey, four schools (two private and two public) were randomly selected. survey respondents from the primary schools were grade eight students who can better understand the questions that appear on the questionnaire. first, the researchers gathered secondary data from wolaita sodo town’s education bureau and from offices of principals in the respective selected four schools regarding the total number of students. wolaita sodo university is clustered in to 3 campuses, six colleges. three colleges (college of social science and humanity, college of business and economics and school of engineering and informatics) were randomly selected with the aim of enhancing the representativeness. because the survey population size was already known, the researchers used yemane’s formula to calculate the total sample size, according to equation 1 and 2 for university and primary school students, respectively. n = 𝑁 1+𝑁 ×(𝑒)2 = 9,582 1+9,582 ×(0.05) 2 = 384 (1) n = 𝑁 1+𝑁 ×(𝑒)2 = 8,643 1+8,643 ×(0.05) 2 = 382 (2) where, n the sample size, n the population size, e the acceptable sampling error, 95% confidence level and p = 0.05 is assumed. probability proportionate to size sampling technique was used to determine the sample size both for students learning in the university and primary school levels. from the total questionnaires distributed, 274 of primary school students (72% response rate) and 262 of university students (68.2% response rate) have properly filled and completed. 2.3. research method and source of data primary data were gathered mainly through the use of survey research method. a self-administered questionnaire was prepared in english, translated in to amharic language to create a better understanding of the questionnaire items among the respondents. the items in the questionnaire were partly taken from mitike yemane and lindtjorn (2008) and adopted to fit in to the context of the current study. then, data collectors, 2 possessing a bachelor degree and one graduating class of sociology department, were trained about the items in the questionnaire and all the things to be done in the process of data collection. following this, a permission letter was secured from the concerned body of wolaita sodo university. next, a pilot test was undertaken to prove compatibility of the questionnaire on few selected students (30 from the university and 30 from the primary school students). the same questionnaire, having similar items, was duplicated according to the sample size of students learning in primary schools and university. in addition, a 5% addition of questionnaire copies was duplicated to substitute potential losses bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 16 before distribution. finally, the actual data collection activity was held from february 19-28, 2020 under the supervision of the principal and co-investigators. during data gathering, data collectors have been clearly instructing respondents about how to fill the questionnaire. a close follow-up was made by both data collectors and supervisors. respondents, especially in the elementary schools were told to freely raise any question that is unclear to them, including on how to respond to the questions. because the questionnaire included some very private questions that may ashame the respondents, data collectors have been controlling and informing respondents to maintain the physical distance between them. the reliability of the instrument was checked through internal consistency of the response items using cronbach’s α while both content and face validity measures were used to maintain its validity. 2.4. instrument in order to assess the value attached to virginity by the respective society/social group to which the students belong, the respondents were asked “to what extent remaining virgin until marriage is valued by the society you come from?” and the response categories being 1) valued/encouraged, 2) discouraged/not valued, 3) do not know. students’ belief of remaining virgin until marriage was measured by asking them: “do you believe that a person should remain virgin until marriage?” and the response categories were: 1) yes, 2) no. furthermore, beliefs about girls’ and boys’ virginity were evaluated by the following two questions: “do you believe in the traditional norm that girls should remain virgin until marriage?” and “do you believe in the traditional norm that boys should remain virgin until marriage?” the response categories for both questions being “yes” and “no”. both boys and girls who choose “yes” about belief in virginity, they were again asked to provide reasons, which include: prevention of hiv, because it is a precondition for marriage, religious prescription, others also customarily doing it, and the need to ensure trustworthiness. furthermore, respondents’ attitude toward virginity was measured on a five point likert scale where 5=strongly agree, 4=agree, 3=neutral, 2=disagree, and 1=strongly disagree with six statements prepared for this purpose. in addition, intention of marrying a virgin for the never married was assessed by the question: “do you want to marry a virgin in the future?” and the response categories were “yes”, “no”, and “indifferent”. above all, the prevalence of premarital sex was examined by asking respondents: “have you ever had viginal sexual intercourse?” with response categories of “yes” and “never”. those who have replied “yes” were again asked “who initiated the first sexual initiation?” and were provided response categories: “personal desire”, “partner influence”, “peer influence”, “rape”, “influenced by drugs”. finally, for those who reported to have had sexual intercourse, the number of sexual partners were evaluated by asking: “with how many persons have you had sexual intercourse?” and the response categories being “one”, “two”, “three”, “four”, “five and above”. 2.5. method of data analysis the questionnaires returned from the respondents were first checked against completeness. the correctly completed ones were then inserted in to software known as statistical package for social sciences. data generated from the software were presented using both descriptive and inferential statistical tools. virginity values and prevalence of premarital sex, including reproductive health behaviors of respondents were analyzed through descriptive statistical techniques such as frequency distributions, tables, and percentages. moreover, data regarding respondents’ attitude toward virginity was analyzed and presented using measures of central tendencies, such as mean, median, and standard deviation. in addition, comparison of virginity values and prevalence of premarital sex between the two categories of students was made by comparing frequency distributions of cases in both categories. furthermore, analysis of factors associated to virginity values was made by both pearson’s correlation and linear regression coefficients. using 95% confidence interval, independent variables for which significance levels were below 0.05 were considered as significantly associated to virginity values, engagements in to premarital sex, and patterns of regular condom use. 3. results the aim of the present study was to assess the value of virginity among the youth in wolaita sodo town, prevalence of premarital sexual practices, and their bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 17 vulnerability to reproductive health risks. quantitative data were collected, sorted, and entered in to spss version 20 for analysis. in this section, the processed data are presented with an interpretation to make the necessary assertions. 3.1. socio-demographic characteristics of respondents table 1 shows the frequency and percentage distribution of the socio-demographic characteristics of survey participants. while most (77%) of respondents in the primary level of education are 11-15 years old, majority (79.4%) of respondents in the university are found to be 21-25 years of age. moreover, sex disparity between the two groups of respondents has also been observed. whereas female respondents (58%) constituted relatively the larger proportion of students in the primary schools, the percentage of males (55.7%) is greater in case of respondents in the university. as far as marital status is concerned, most of the respondents in both groups (85.4% in primary, 86.6% in university) have never married. furthermore, while majority (63%) of respondents in the university disclosed to be followers of orthodox christianity, protestantism dominated the religious faith among the primary students (56.2%). the residential background of respondents has been found to be urban (81.4%) for the larger proportion of primary students while respondents who reported to come from rural areas dominated the proportion of university students (59.2%). this variation might have happened due to the fact that most of the students in most ethiopian primary schools in general, and the study area in particular, are from the nearby areas surrounding the schools. above all, the current marital status of parents of respondents shows that most (81% among primary students, 81.7% among university students) of the parents in both groups are reported to be still in wedlock. table 1: socio-demographic characteristics of respondents no. variable categories of responses frequency (%) of elementary students n=274 frequency (%) of university students n=262 1. age 11-15 211 (77%) 1 (0.4%) 16-20 62 (22.6%) 42 (16%) 21-25 1 (0.4%) 208 (79.4%) 26-30 8 (3.1%) 31-35 2 (0.8%) 36-40 1 (0.4%) 2. sex female 159 (58%) 116 (44.3%) male 115 (42%) 146 (55.7%) 3. marital status married 24 (8.8%) 30 (11.5%) never married 234 (85.4%) 227 (86.6%) divorced 14 (5.1%) 4 (1.5%) widowed 2 (0.7%) 1 (0.4%) 4. religion orthodox christian 70 (25.5%) 165 (63%) muslim 29 (10.6%) 29 (11.1%) protestant 154 (56.2%) 61 (23.3%) catholic 6 (2.2%) 3 (1.1%) joba 2 (0.7%) atheist 2 (0.8%) others 13 (4.7%) 2 (0.8%) 5. residential background rural 51 (19.6%) 155 (59.2%) urban 223 (81.4%) 107 (40.8%) 6. parents’ current marital status still in wedlock 222 (81%) 214 (81.7%) divorced 26 (9.5%) 21 (8%) widowed 18 (6.6%) 21 (8%) separated 8 (2.9%) 6 (2.3%) bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 18 3.2. the value of virginity in mate selection table 2 presents frequency distribution of responses regarding the place of virginity in the value system of respondents leading the personal relationships they intend to create with other persons in the opposite sex. according to the data in table 2, virginity has generally been found to be valued by the respective societies which respondents are a member. relatively speaking, the value of virginity was higher in the society from which university students come (82.4%) than the case in the primary school students (59.9%). moreover, higher proportion of primary school students reported to give an emphasis on the value of staying virgin until marriage (91.2%) compared to their university students counterparts (87%). the main reason for primary level students to believe in the importance of remaining virgin until marriage has been found to be its contribution to protect oneself from various sexually transmitted infections, including hiv/aids (43.4%), followed by religious prescription (20.1%), and the need to ensure the trustworthiness of a spouse (19.7%). the issue being a religious prescription was reported to be the main reason (56.5%), followed by the need to ensure trustworthiness (16.4%) and consideration of virginity as a precondition for marital relationships (13.4%), in case of university students. most male respondents both in the primary schools (32.5%) as well as in university (42.7%) believe in the traditional norm that girls should remain virgin until marriage. similarly, majority of females in both groups of respondents (52.9% of primary, 35.5% of university students) believe in the norm that boys should remain virgin until marriage. from the data, it can be understood that girls place a relatively higher value to boys’ virginity than boys do among students in the primary school students (52.9% females need boys to remain virgin compared to 32.5% of boys who reported to value girls’ virginity) while the reverse is true in case of university students (42.7% of boys reported to value girls’ virginity compared to 35.5% girls who replied to value boys’ virginity). data also reveals a high need of marrying a virgin spouse in the future among the respondents of both groups (78.1% primary school students, 71% of university students). table 2: the frequency distribution of value of virginity among the respondents no. variable/question categories of responses frequency (%) of primary school students n=274 frequency (%) of university students n=262 1. the extent to which virginity is valued by the society respondents come from virginity is valued 164 (59.9%) 216 (82.4%) not valued 21 (7.7%) 23 (8.8%) do not know 89 (32.5%) 23 (8.8%) 2. belief in remaining virgin until marriage yes 250 (91.2%) 228 (87%) no 24 (8.8%) 34 (13%) 3. reasons to believe in virginity to protect oneself from stis 119 (43.4%) 23 (8.8%) considering it as a precondition for marriage 28 (10.2%) 35 (13.4%) it is prescribed by my religion 55 (20.1%) 148 (56.5%) to ensure trustworthiness 54 (19.7%) 43 (16.4%) others also customarily believe so 5 (1.8%) 9 (3.4%) no reason 10 (3.6%) 4 (1.5%) missing 3 (1.1%) 4. boys’ belief towards the norm that girls should remain virgin yes 89 (32.5%) 112 (42.7%) no 30 (10.9%) 33 (12.6%) missing 155 (56.6%) 117 (44.7%) 5. girls’ belief towards the norm that boys should remain virgin yes 145 (52.9%) 93 (35.5%) no 17 (6.2%) 25 (9.5%) missing 112 (40.9%) 144 (55%) 6. the need to marry a virgin in the future (for the never married) yes 214 (78.1%) 186 (71%) no 18 (6.6%) 15 (5.7%) indifferent 39 (14.3%) 61 (23.3%) missing 3 (1.1%) bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 19 data presented in table 3 and figure 1 are attempts of assessing the value of virginity among the respondents measured using likert scale. specifically, data in table 3 is about a comparative distribution of virginity value between respondents of the two groups on the basis of the various measures of central tendency. accordingly, it is found that the respondents in both groups have positive attitude toward virginity and its role to create and maintain spousal relationships has been pronounced. for instance, majority of the respondents expressed that they consider virginity as the main criterion to engage in love or marital relationships (mean=4.17 for primary school students, 3.94 for university students). similar to the above finding, respondents in the primary schools have shown a relatively higher positive attitude towards virginity. furthermore, figure 1 compares the aggregate mean of attitude held towards the value of virginity by both primary school and university students. the aggregate mean for both groups of research participants is found to be above 3 which imply the presence of positive attitude towards the value of necessity of remaining virgin until marriage. comparing the mean of the two groups, it is indicated that the mean of attitude for primary school students is 3.45 while in case of university students, it is found to be 3.01. it suggests that primary school students hold more favorable attitude towards maintaining virginity than their university students counter parts. 3.3. premarital sexual practices and vulnerability to reproductive health risks data presented in table 4 shows the frequency distribution of respondents in terms of experiences of engaging in premarital sex and related practices that may expose them to various reproductive health risks. it is found that 18.2% of primary school students reported to have engaged in premarital sexual practice which is lower than the rate we found among the university students (33.2%). furthermore, while partner influence makes the highest percentage share (36%) of reasons to start premarital sex among primary school students followed by self-initiation (32%), most (42.5%) of such a practice was initiated by the respondents themselves followed by partner influence (29.9%) among university students. out of the respondents who reported to have had premarital sexual practices, 19 (38%) of primary school students and 52 (59.8%) of university students disclosed to have sexual relationships only with a single partner, though experiences of having more than one life-time sexual partners have also been found, as presented in table 5. for instance, 20% of primary school students and 19.5% of university students reported to have sexual intercourse with five and more persons. moreover, better prospects of regular condom use during sex have been observed among the respondents in both groups. while 62% of primary school students reported to regularly use condom during sex, 56% of them disclosed to have the experience of undertaking voluntary hiv testing before doing sexual intercourse. in addition, table 3: frequency distribution of the value of virginity among respondents as measured on a likert scale measures of central tendency variable/ statements on the likert scale mean median std. deviation variance sum pst. ust. pst. ust. pst. ust. pst. ust. pst. ust. virginity is my major criterion to engage in love or marital relationships 4.17 3.94 5.00 5.00 1.449 1.336 2.099 1.786 1143 1033 i am not willing to start a relationship with non-virgin person 3.44 3.11 4.00 3.00 1.666 1.507 2.775 2.270 943 816 i don’t mind about the virginity status of a person when intend to start a relationship 2.72 2.68 2.00 2.00 1.657 1.446 2.745 2.090 745 701 i will never marry a person that is not a virgin 3.37 2.73 4.00 2.00 1.606 1.472 2.579 2.168 924 715 someone is a virgin means that s/he is trustworthy for marital relationship 3.72 2.99 5.00 2.50 1.578 1.519 2.490 2.306 1018 784 i will never start love or marital relationships unless i get a virgin 3.28 2.63 3.00 2.00 1.648 1.477 2.716 2.181 899 688 note: pst. = primary school students, ust. = university students bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 20 figure 1: comparison of mean of attitudes towards value of virginity for both categories of students. primary school students have been found to be better in terms of engaging in less risky premarital sexual practices compared to their university students counterparts (59.8% to 62% in regular condom use; 56% to 55.2% in undertaking hiv testing before engaging in sexual practices, respectively). finally, most respondents in both groups (76% of primary school students, 67.8 of university students) have reported to care for pregnancy than other sexually transmitted infections, which might expose them to various reproductive health risks. table 4: frequency distribution of respondents in terms of experiences in premarital sex no. variable categories of responses frequency (%) of primary school tudents n=274 frequency (%) of university students n=262 1. experiences of sexual intercourse yes 50 (18.2%) 87 (33.2%) never 224 (81.8%) 175 (66.8%) 2. what/who initiated first sexual intercourse self/personal desire 16 (32%) 37 (42.5%) partner influence 18 (36%) 26 (29.9%) peer pressure 10 (20%) 11 (12.6%) rape 2 (4%) 5 (5.7%) influenced by drug/s 3 (6%) 6 (6.9%) others 1 (2%) 2 (2.3%) total 50 (100%) 87(100%) 3. number of sexual partners 1 19 (38%) 52 (59.8%) 2 17 (34%) 12 (13.8%) 3 3 (6%) 5 (5.7%) 4 1 (2%) 1 (1.1%) 5 & above 10 (20%) 17 (19.5%) total 50 (100%) 87(100%) 4. experiences of regular condom use yes 31 (62%) 52 (59.8%) no 19 (38%) 35 (40.2%) total 50 (100%) 87(100%) 5. ever had sex without undertaking hiv testing yes 22 (44%) 39 (44.8%) no 28 (56%) 48 (55.2%) total 50 (100%) 87(100%) 6. during sex, i care not to conceive than i care for hiv/aids. yes 38 (76%) 59 (67.8%) no 12 (24%) 28 (32.2%) total 50 (100%) 87(100%) bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 21 3.4. factors associated to value of virginity, premarital sex, and condom use in the following sub-section, an attempt has been made to analyze the association between respondents’ sociodemographic characteristics (age, sex, religion, marital status, residential background, and parents’ current marital status) and their value to virginity, engagements in to premarital sex, and experiences of regular condom use. the association was tested using both correlation and regression coefficients as presented in table 5 and 6. it is found that primary school students’ value of virginity was found to be positively associated to the sex (r (274) =.181, p<.01) and marital status (r (274) =.174, p<0.01) of respondents, i.e. being female and never married, and a higher value to virginity are positively associated. in addition, university students’ virginity value is associated to their residential background (r (262) =187, p<0.01), i.e. coming from an urban area and a higher value to virginity are positively associated. furthermore, respondents’ experience of engaging in premarital sexual practices is associated to the sex of respondents for both groups alike (r (274) =-.429, p<0.01, df = n1 +n2 -2 = 536 among the primary school students and r (262) =.237, p<0.01 for university students), i.e. being female is negatively associated to experience of premarital sex or more males have reported to have engaged in premarital sex than their female counterparts. above all, respondents’ experience of regular condom use has been found to be positively associated to the sex (r (274) =.217, p<0.05) of respondents in case of primary school students. in other words, being male and the experience of regular condom use are positively associated. as shown in table 5, the level of association for all sex, marital status, and residential background is significant. table 6 presents regression coefficient data regarding the nature and extent of association between the dependent and independent variables. the coefficients of regression confirm the findings obtained by using correlation coefficients indicated in table 5. once again, while sex, marital status, and residential background were found to be significantly associated to respondents’ virginity values, engagements in premarital sex, and experience of regular condom use, age, religious affiliation, and parents’ current marital status have no significant association. looking in to both the standardized and the unstandardized coefficients in the table, we find that sex, marital status, and residential background are positive significant predictors of respondents’ value of virginity while and sex is a negative predictor for engagement in premarital sexual intercourse. in other words, a one point increase in sex differences among the respondents results in a 0.97 increase in the value of virginity. in addition, a one point increase in respondents’ residential background differences brings about a 0.135 increase in their value of virginity. moreover, every one point increase in the marital status results in a 0.113 increase in their value toward virginity. on the other hand, every additional difference in the sex of respondents decreases their experience of premarital sex by -.333. generally, whereas being female (0.97, p<0.05), coming from an urban area (r=.135, p<0.05), and being never married (r=.133, p<0.05) are positive predictors of value toward virginity, being female (r=-.333, p<0.05) is found to be a negative predictor of young people’s experience of premarital sexual practices. table 5: frequency distribution of respondents in terms of experiences in premarital sex dependent variable/s correlation coefficients independent variables age sex marital status religion residence parents’ marital status pst. ust. pst. ust. pst. ust. pst. ust. pst. ust. pst. ust. virginity value pearson correlation -.048 .062 .181** .047 .174** -.089 -.083 .015 .082 187** -.063 .055 sig. (2-tailed) .428 .320 .003 .449 .004 .152 .169 .812 .177 .002 .298 .372 premarital sex pearson correlation -.024 -.042 -.429** .237** -.026 .066 .099 -.088 .084 .042 -.078 .056 sig. (2-tailed) .697 .500 .000 .000 .673 .284 .103 .154 .163 .501 .199 .371 condom use pearson correlation .057 .207 .045 .217* .177 .056 -.092 -.170 -.042 -.072 .093 -.175 sig. (2-tailed) .694 .053 .756 .043 .220 .604 .526 .114 .770 .507 .521 .104 **. correlation is significant at the 0.01 level (2-tailed). *. correlation is significant at the 0.05 level (2-tailed). bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 22 table 6: linear regression coefficients dependent variable/s regression coefficients independent variables age sex marital status religion residence parents’ marital status pst. ust. pst. ust. pst. ust. pst. ust. pst. ust. pst. ust. virginity value b -.012 .043 .097 .041 .113 -.087 -.012 -.003 .073 .135 -.035 .020 st. error .039 .043 .034 .044 .042 .056 .013 .020 .044 .043 .023 .029 beta -.019 .065 .169 .061 .163 -.095 -.056 -.011 .100 .198 -.090 .043 sig. .752 .316 .005 .355 .007 .122 .352 .863 .097 .002 .136 .489 premarital sex b .008 .018 -.333 -.220 .045 .068 .016 -.033 .051 .011 -.021 .017 st. error .051 .060 .044 .062 .054 .078 .016 .027 .056 .059 .030 .041 beta .008 .019 -.422 -.232 .047 .053 .054 -.075 .051 .012 -.039 .026 sig. .881 .763 .000 .000 .407 .387 .333 .224 .364 .852 .482 .670 condom use b .104 .135 -.067 .145 .134 .039 -.045 -.052 -.087 -.072 .047 -.059 st. error .156 .136 .217 .131 .106 .142 .071 .047 .180 .110 .081 .084 beta .106 .119 -.053 .133 .202 .029 -.109 -.119 -.077 -.071 .086 -.079 sig. .506 .324 .758 .269 .212 .787 .527 .275 .631 .512 .570 .487 note: pst. = primary school students, ust. = university students 4. discussion the loss of one’s virginity is mostly understood as a remarkable event in the life of both boys and girls (solin, 1996). in fact, parental monitoring during preadolescence affects the age at which adolescents start and begin sexual activity (ajidahun, 2013). the literature is full of contradictory findings about the value of virginity among young people in various societies across the world. while the traditional value of virginity still remains unchanged in most societies, it is declining in some others. for instance, according to ajidahun (2013), modern civilization and sexual revolution have affected nigeria’s traditional norms and values to the extent that nobody values virginity as it used to be in the past. mitike molla et al. (2008), on the other hand, found that maintaining virginity is still a way of securing marriage for girls living in rural areas of ethiopia. even in the same societyethiopiaother researchers (meles, et al., 2016), found poor value of virginity and high prevalence of early sexual practices among youth. it was in this context that the present research was conducted with the aim of understanding if the value of virginity still persists among young people in ethiopia. accordingly, it was found that youth in ethiopia highly value virginity (91.2% among youth learning in the primary schools and 87% among those studying in a university). furthermore, research participants not only disclosed to value virginity, but also reported that virginity is valued among the respective societies they come from (59.9%; 82.4%) as shown in table 2. moreover, 78% of young people learning in the primary schools and 71% of those attending undergraduate courses in the university also replied that they need to marry a virgin in the future. above all, virginity is a major criterion for most (mean= 4.17, 3.94 for primary school and university students respectively) of the young people participated in the present research. with these in mind, the finding of this study is consistent with the finding of mitike molla et al. (2008) and contradicts with both meles et al., (2016) and that of ajidahun (2013). both correlation and regression coefficients presented in table 5 and 6 of the present study reveal that sex, marital status, and residential background of respondents are significantly associated to virginity value, engagement in to premarital sex, and the use of condom at a regular basis. in addition, data from descriptive statistics presented in table 2 show that girls place a relatively higher value to boys’ virginity than boys do among students in the primary school students (52.9% females need boys to remain virgin compared to 32.5% of boys who reported to value girls’ virginity) while the reverse is true in case of university students (42.7% of boys reported to value girls’ virginity to 35.5% girls who replied to value boys’ virginity). consistent to this, mitike molla et al. (2008) emphasized the effect of residential background influencing the extent to which virginity is differently valued between rural and urban areas saying that rural youth were three times more likely to believe in the bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 23 traditional norm of remaining virgin until marriage. carpenter (2002) observed an increasing similarity among men and women alongside persistent differences, the most disturbing of which is young women’s relative disempowerment at virginity loss. girls bear more responsibility for premarital virginity loss (matswetu and bhana, 2018). patriarchal values produce sexual double standards whereby virginity has greater significance for females compared to males (palit and allen, 2016). some people may engage in premarital sexual practices with many sexual partners and therefore they may have high number of life time sexual partners that could be liable to acquire sexually transmitted infections including human immune deficiency virus (vos, 2004). in the present research, we found a relatively low prevalence rate of premarital sex among primary school students which increases as we move to the university. moreover, patterns of initiating firsttime sex among the respondents show that sexual partner influence among primary school students and self-initiation among university students make up the highest percentage distribution as presented in table 4. findings of the present study contradict to the findings of most other researches previously undertaken in different areas of ethiopia. many of these studies (e.g. geremew kindie et al., 2017; tomas benti et al., 2015; bayisa abdissa et al., 2017; addisu shunu et al., 2014; daba banr 2006; netsanet habte et al, 2018) found a high prevalence of premarital sexual practices in various areas of ethiopia. ajidahun (2013), in a study conducted in nigeria concludes: youths are so free that sexual act can even be done in open, and they are no longer ashamed to engage in such act (ajidahun, 2013). 5. conclusions and recommendations 5.1. conclusion youth living and learning in wolaita sodo town during the time of the current study have a high value to virginity in general and the importance of staying virgin until marriage in particular. moreover, while a relatively low level of engaging in premarital sexual practices has been reported, prospects of using condoms at a regular basis are promising. it is also found that premarital sexual practice is low among primary school students and increases as we move to the university. both correlation and regression coefficients indicated that youths’ value of virginity, their engagements in premarital sexual practices, and their experiences of using condom on a regular basis is significantly associated to their sex, marital status, and residential background. above all, the finding that some cases of having more than one life-time sexual partners are prevalent added to the fact that most reported to care for pregnancy than the risk of contracting sexually transmitted infections during sexual intercourse may enhance young peoples’ vulnerability to various reproductive health risks. the researchers believe that the use of mixed research approach better benefits the study. however, because the issue is sensitive and mostly considered as taboo, qualitative data were not collected due to the assumption that the presence of an interviewer may provoke research participants to provide socially desirable responses. furthermore, most of the items in the questionnaire were adopted from previous researchers and some others were partly constructed by the researchers. consequently, a standardized questionnaire was not used and that might have resulted in some validity and reliability concerns as far as measurement is concerned. above all, although more than 95% of the distributed questionnaires were returned from both groups of respondents, some of them were incomplete and hence, were rejected that reduced the response rate. therefore, the response rate has been 72% and 68.2% for respondents of primary school students and university students respectively which is lower than the response rate of most previous studies undertaken on related topics. although fair, such low response rate could have affected the findings of the study and the generalizations made out of it. 5.2. recommendations it is important that continued reproductive health care trainings should be given to university students, especially females and those coming from rural areas, to refresh and enhance their awareness on risks related to engagements in unsafe premarital sexual practices and reluctance over regular use of condoms. the relatively higher freedom enjoyed among university students due to being physically located mostly far away from family networks opens the way for engaging in (risky) sexual behaviors and hence, instigates attention from bewunetu zewude et al. ethiop.j.sci.sustain.dev., vol. 8 (1), 2021 24 practitioners of guidance and counseling, teachers, and all other concerned stakeholders. furthermore, similar interventions should also be geared towards both categories of students given findings of having multiple sexual partners among both groups of respondents. reference addisu shunu beyene, & abdulbasit musa seid. 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(2006). assessment of premarital sexual practices and factors related to it among ambo high school students. unpublished thesis submitted to the faculty of medicine of addis ababa university in partial fulfillment for the requirements of obtaining master degree in public health geremew kindie behulu, kiber temesgen anteneh & getie lake aynalem. (2017). premarital sexual intercourse and associated factors among adolescent students in debre-markos town secondary and preparatory schools, north west ethiopia, 2017. bmc res notes, 12:95, https://doi.org/10.1186/s13104-019-4132-4 goody, j. (1976). bride wealth and dowry in africa and eurasia. cambridge papers in social anthropology no. 7. cambridge: cambridge university press. jessor, shirley l., & jesser, r. (1975). transition from virginity to non-virginity among youth. developmental psychology 11:473-84. laumann, e. 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(1991). status, property, and the value on virginity. american ethnologist, 18(4): 719-734 solin, s. (1996). the seventeen guide to sex and your body. new york: simon & schuster tomas benti teferra, asfaw negesso erena, and anteneh kebede. (2015). prevalence of premarital sexual practice and associated factors among undergraduate health science students of madawalabu university, bale goba, south east ethiopia: institution based cross sectional study. pan african medical journal, 20:209 vos, t. (2004). attitudes to sex and sexual behavior in rural matabeleland, zimbabwe. aids care, 6(2):193-203. https://doi.org/10.1186/s13104-019-4132-4 https://doi.org/10.1177/215824401877910 31 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper sanitation in borena pastoral community of ethiopia: pinpointing the status and challenges moti mosisa1,*, abrha mesele1, belayneh bogale2, kiflie work1 1dilla university, p. o. box 419, dilla, ethiopia 2kotebe metropolitan university, faculty of business and economics, p. o. box 31248, addis ababa, ethiopia * corresponding author, e-mail: mosi.moti@gmail.com abstract in ethiopia, the pastoralists cover 61% of the land area and constitute 12-15% of the total population. regardless of this fact, studies confirmed that pastoralists were away from the central government for a long, and have been among the most marginalized group in terms of availability and access to public services including sanitation services. thus, the objective of the study was to study the status, challenges and prospects of sanitation in borena pastoral community of ethiopia. descriptive survey research design with mixed methods of data collection and analysis, were utilized based on primarily evidences collected from local communities, government sectoral offices, and non-government organizations in the sector. accordingly, the access to all types of latrine in the zone was estimated to be close 68%, however significant proportion of the latrines were unimproved and traditional pits. moreover, poor water supply, mobile life style of the community, soil property, lack of qualified man power and habit of open defecation were found to be the major impediments. regarding the prospect, the health extension program, the availability of multiple actors and the one wash program are the prominent ones. in order to improve the sanitation coverage by tackling the aforementioned challenges, inter alia, scaling up the best practices of relatively good performing woredas and enhancing the engagement of the community are recommended. keywords: pastoralist, sanitation, latrine, hygiene and development. 1. introduction pastoralism is a lifestyle based on the breeding, rearing and grazing of camels, cattle, sheep and goats in dry land. people classified under this life style move from place to place in search of water and ample pasture for their livestock (blench, 2001). in ethiopia, the arid and semi-arid areas which cover 61% of the land area of the country are homes for millions of pastoralists of diverse ethnic groups. moreover, pastoralists constitute 12-15% of the total population of the nation, supports 40% of the cattle, 75% of the goats, 25% of the sheep, 20% of the equines, and 100% of the camel population in the country (gebru et al., 2004; abrha, 2015). despite the visible and significant role of pastoralists in the national and regional economy, as they are living in peripheral areas and due to their mobile life style, they are usually marginalized from development and, face many challenges to support their livelihood (fareh, 2011; abrha, 2015). among the many challenges, the issue of sanitation is one and the major. estimates of 2.4 billion people in the world are not using improved sanitation. in rural areas of developing countries, seven out of ten people live without improved sanitation facilities, and nine out of ten people live practicing open defecation. the least developed countries did not meet the global sanitation targets, and only 27 % of their current population gained access to improved sanitation since 1990. statistically 15% of the world population practice open defecation of which http://www.ejssd.astu.edu/ mailto:mosi.moti@gmail.com moti mosisa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 32 ethiopia’s share is 38 million people manly pastoralists and agro-pastoralists (jmp, 2012). in ethiopia, the emerging regions such as afar, somali, benshangul gumuz, gambella and pastoralist areas of oromia are facing unique challenges in terms of health service delivery in general and hygiene and sanitation in particular. figures on toilet access and hygiene practice are low, implying high risk to health. as large numbers of livestock and people are competing for limited water supplies, and open defecation is practiced, the areas are vulnerable to rapid fecal-oral disease transmission including outbreaks of acute watery diarrhea (awd) (moh, 2011). in this regard, though there are multiple government and nongovernmental organizations report, little fullfledged research output are available. hence, this study has addressed the status, challenges and prospects of rural sanitation in pastoral community of borena. 2. methods and materials the study has taken different methods and approaches based on each research questions. as it described the sanitary practices, the research took, firstly, descriptive form. secondly, as the study answered questions such as why and how of sanitary practices and, explains the reasons behind, it took explanatory form. moreover, as the phenomenon of the study is dynamic by its nature and need to be seen from different dimensions, mixed-approach has been utilized with pragmatist philosophy. in addition, the study utilized both primary and secondary data sources using questionnaire, in-depth interview, observations, fgd and review of documents as instruments. multistage sampling method was employed for this study. out of the total (13 woredas in the zone) seven woredas were purposefully selected based on their relevance to the study and their representations, as recommended by the zone administration and official sanitation related reports. 4 of the woredas (elwaye, guchi, dire and yabello), were chosen to represent areas with poor sanitation records while the other 3 woredas (moyale, dillo and miyo) were chosen to represent areas with relatively better sanitation practices. these seven woredas constitute 78,308 pastoral and semi-pastoral households. hence, through the application of kothari (2004) sample size determination formula, sample sizes of 383 households were drown. proportional household’s allocation to the seven woredas was also applied. finally, the allocated proportion for each woreda was re-allocated to three judgmentally selected kebeles in each woreda. furthermore, individual households in the selected kebeles were targeted by using convenience sampling technique. in addition to this, the researchers used judgmental sampling technique for collecting information from non-governmental organizations (ngos) and target interviewees and fgd participants. on the other hand, regarding the methods of data analysis the narrative and descriptive methods were utilized. 3. results and discussion 3.1. sanitation: status, challenges and prospects 3.1.1. status of sanitation in borena zone a) access to latrine latrine is a basic infrastructure for community health care. it is a basic sanitation facility to reduce water contamination and creates a healthy environment. latrines, when used by adults and infants for the disposal of feces, can reduce diarrhea by 36%, cholera by 66%, and worm infestations by between 12 and 86% (moh, 2006). given this significant contribution, the study assessed the extent to which pastoral households have private or communal latrine. figure 1, below, revealed that 254 (72.6%) of the respondents do have private or communal latrine while the remaining 96 (27.4%) do not have any form of latrine facility. figure 1: private or communal latrine ownership (source: research team survey (2017/18)) the zonal report also confirmed that 68% of the borena pastoralists have access to latrines. however, the moti mosisa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 33 coverage varies from one woreda to another ranging from 27% in wachile to 97% in dubluk. table 1: latrine coverage (source: zonal report, 2017) households with all types of latrine s. no sampled woreda households all type -coverage number percentage 1 dillo 5,680 3,358 59 2 dire 9,633 9,022 94 3 eelwaye 9,782 5,418 55 4 guchi 22,220 9,881 44 5 miyo 14,313 11,057 77 6 moyale 33,483 24,376 73 7 yabelo u. 5,464 5,085 93 8 yabelo r. 9,252 6,924 75 total 75,121 71 table 1 shows that in the sampled seven woredas (including all the pastoral, semi-pastoral and nonpastoral households), the urban part of yabelo and guchi were the best and least performers in latrine coverage with 93 and 44 percents respectively. table 2: reason for not having latrine and latrine typologies (source: research team survey (2017/18)) reason for not having private latrine(n=96) f % economic factor 33 34.4 know-how 29 30.2 cultural/social 3 3.1 other factors 31 32.3 total 96 100 latrine type f % traditional pit latrine (quasiimproved) 117 46.1 improved latrine 3 1.2 unimproved latrine 134 52.7 total 254 100 there are several reasons for non-adoption of latrine. the most common factors are related to poverty, socio cultural issues, and technical difficulties. as it can be seen from table 2, 33(34.4%) of the respondents stated that they did not have private latrines because of economic problems while 29(30.2%), 31(32.3%) and 3 (3.1%) of respondents revealed that they did not have private toilets because of lack of know-how, frequent resettlement, and cultural/social factors respectively. according to similar table, 134 (52.7%) of the respondents had unimproved latrine, and 117(46%) had quasi-improved traditional pit latrine. only 3(1.2%) of the respondents had a standard improved latrine. the dominant types of latrine that were constructed in the study areas were open pit latrine without slab, open pit latrine without house, pit latrine with walls but without roof, and pit latrine with closed wall and roof but without door. through the research teams observation it was confirmed that the walls of these latrines didn’t totally maintain the privacy of users. particularly women were forced to use open field far away in the back yard. the above finding is also confirmed by moh (2011) stating most of the traditional latrines in ethiopia don’t address expressed concerns about smell, rising gas, structural collapse, fear of falling in, flies, privacy and shelter from the elements. photo credit: research team (2017/18) moti mosisa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 34 96 254 350 27.4 72.6 100.0 yes no total valid avilability of hand washing facility near latrine frequency avilability of hand washing facility near latrine percent 52 23 20 1 96 54.2 23.9 1.0 100.0 0 50 100 150 field forest bushes others total open defecation practices place of open defication percent place of open defication frequency as can be seen from the above photos, the suitability and quality of the latrines is quite poor, and sanitary conditions are deficient. many of the latrines in the study area are built without proper design, materials or technical assistance from government and partners. latrine slabs are often difficult to clean and unsafe for users. b. availability of hand washing facilities hand washing is an intervention that is directly related to the accessibility of water, and it can be a primary or secondary barrier to transmission of pathogens. according to moh (2011), for ethiopia, it was estimated that a 50% reduction in the incidence of diarrhea can be achieved with the use of latrine and practice of hand washing. figure 2: hand wash facility (source: research team survey (2017/18)) the above figure reveals that 96 (27.4%) of the respondents had hand washing facilities near their latrines, whereas 254 (72.6%) did not have such facilities near their latrines. in line with this, the respondents were asked about their hand washing habit in some of key sanitation indicators like after defecation, after cleaning babies, before preparing food, before eating and before feeding children. based on this, 159(45.4%), 102 (29.1%) and 89 (25.4%) of respondents replied that they wash their hands sometimes, not at all and frequently respectively. regular use of toilet and proper hand washing with soap (or substitute) and water at appropriate times by all family members are still not widely practiced in the study areas. this was also confirmed by curtis et al (2000) who stated that in developing countries only 11% of people washed their hands after using latrine, and even fewer people used soap. c. open defecation (od) out of the total respondents, 52 (54.2%) reported defecating in an open air field and back yards because they did not have private latrines, while 45 (44.7%) defecate in forest and bushes. as per respondents response about the daily time spent to find private location to defecate, the study team has made an estimation on the annual time loss per head. accordingly the finding revealed that each person who practices open defecation spends almost 25 days a year finding a location to defecate leading to large economic losses. this cost falls disproportionately on women as caregivers who may spend additional time accompanying young children or sick or elderly relatives. figure 4: open defecation practices (source: research team survey (2017/18)) table 3 shows that, out of the total sample respondents who owns private latrine, only 49 (19.3%) asserted that their latrines were always comfortable to use, while 205 (80.7%) of them revealed that their latrines were not comfortable and not functioning all the time. in addition, the table shows that the latrines of 50.7% of the respondents did not function during rainy seasons while, 21.9% and 15.1% of the respondents said that their latrines were not comfortable to use during day times and night times respectively. similarly, worku (2007) reported that 30-80% of the latrines in ethiopia are non-functional because of unavailability of durable building material and poor design of latrines. moti mosisa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 35 87 138 102 23 350 24.9 39.4 29.1 6.6 100.0 0 100 200 300 400 soap and water ashe and water water only water and traditional plants total hand wash materails hand wash materials percent hand wash materials frequency d. physical condition of latrines latrine can be built with locally available materials such as wood, bamboo, poles, mud brick, cement brick, clay, stone, and corrugated iron sheet. in similar vein, the study assessed the suitability of latrine design for usage, its comfort for children, and the hand washing inputs used. table 3: functionality of latrine (source: research team survey (2017/18)) is the latrine comfortable to use all the time? frequency percent reason of dis-functionality frequency percent yes 49 19.3 discomfort in rainy season 104 50.7 no 205 80.7 discomfort during daytime 45 21.9 discomfort during nighttime 25 12.2 poor hygiene and bad smell 31 15.1 total 254 100 total 205 100 table 4: design of latrines and comfortably (source: research team survey (2017/18)) the above table shows that 209 (82.3%) of respondents stated that, the design of their latrine does not fulfill the minimum design requirements. on the other hand, the remaining 45 (17.7%) replied that their latrine fulfills the minimum design requirement. thus, despite the increasing trend of latrine coverage, the design quality of latrines being constructed in borena zone is below the minimum requirement. accordingly, as per the researchers’ observation, most of the latrines don’t have the required facilities. most of the latrine observed were simply made by digging a hole in the ground and covered by row of woods without roof, door and walls. as a result, the durability of latrines is poor and mostly affected by wind and heavy rain. in similar vein, 213 (83.9%) of the respondents stated that their children do not use the latrine due to the risky and unhygienic nature of their latrines, while the remaining 41 (16.1%) replied that their children use latrine. similarly, a report by unicef in 2013 showed that ethiopian latrines are below standard in terms of suitability for children, elderly and disabled persons. furthermore, the study investigated the materials they use to wash their hands after defecation. accordingly, 138 (39.4%), 102 (29.1%), 87 (24.9%) of the respondents use ashes and water, only water, and soap and water respectively for washing their hands after defecation. the remaining 23 (6.6%) of the respondents use water and traditional plants to wash their hands. therefore, from the above data, it can be concluded that the number of people who use water and soap to wash their hands is smaller in the study area. this confirms the result in developing countries where less than 11% of people wash their hand after using latrine using soap and water (curtis et al., 2001). figure 5: hand washing materials (source: research team survey (2017/18)) does the design fit to purpose frequency percent children’s habit in using latrine frequency percent yes 45 17.7 yes 41 16.1 no 209 82.3 no 213 83.9 total 254 100 total 254 100 moti mosisa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 36 3.1.2. challenges of sanitation service in borena zone poor water supply: water and sanitation are the two sides of the same coin, and it is a plain fact that sanitation needs access to water supply. in borena, shortage of water supply is a key challenge confronting sanitation. according to the zonal wash focal person, there is interplay between water supply and sanitation related targets. he further stated that the poor water supply is critically challenging their effort in meeting the sanitation targets as thinking of sanitation without water is just like putting the cart before the horse. mobile life style of the community: traditionally, pastoralism is linked with mobility. though there are some sedentary and agro-pastoral communities in the area, the lion’s share of the borena pastoral community travels from place to place in search of better pasture and water. this reality is withdrawing the appetite of the people to construct latrines, and if they do, they build only a temporary open pit latrine for provisional usage. according to key informants at zonal and woreda health and pastoral affairs offices, recently, due to village settlement programs, the level of sedentary life and basic infrastructural services are booming. however, settlement in new places is a long term agenda in the study area, and mobility is expected to continue to challenge the provision of sanitation services for a long time. soil property: as far as the observation and the information obtained from key informants is concerned, the soil in most parts of borena low land is easily erodible and partly sandy. this made the construction of traditional latrines, with tradition technique and material, very difficult as the constructed latrine facility will easily collapse during the rainy season and by strong wind. lack of qualified man power: the key informant interviews and fgds carried out with sectorial experts reveal that, there is lack of health professionals and extension agents who are believed to be the backbones of any sanitation related initiatives. in addition, the problem is getting worse as a result of high degree of health professionals turnover. as a result, six of the 14 woredas in the zone do not even have one environmental health processional while the remaining woredas have a maximum of two professionals. however, none of the woredas have fulfilled the minimum number of environmental health professional required as per the structure. from this, one can clearly understand the severity of the human resource related challenge in the area. habit of open defecation: the observation and the fdgs conducted revealed that individuals defecate in fields, bushes, and backyards. besides, as it has been shown in the above section, the quality of latrine facilities is poor and the design of latrines facility is risky. thus, almost all kids in rural areas practice open defecation. as a result health extension workers are facing challenge to combat this long established habit of open defecation in some kebeles. 3.1.3 prospects of sanitation service in borena zone health extension program: as the main objective of health extension program is to provide equitable, preventive and selective basic health services to the community through establishing health posts at local level and training health extension workers, the existence of the program is one of the prospects in the area. the interviews conducted with local dwellers revealed that the health extension workers are creating awareness about sanitation and environmental hygiene. thus, the availability of local health posts and health extension workers could be taken as opportunities to improve the level of sanitation in the area. availability of development partners: as it has been shown in the above section, multiple actors are engaged in helping the pastoralists particularly in health and sanitation sector. thus, if partners are coordinated and best utilized through creating synergy and having a forum and consortium, their efforts can orchestrate so that the problem at hand could be curbed. one wash program and its projects: the one wash national program is the ethiopian government’s main instrument for achieving the goals set out for sanitation and hygiene in the country’s growth and transformation plan (gtp). the program is basically aimed at improving the health and wellbeing of communities by increasing access sanitation and adoption of good hygiene practices. in the study area, a total of five woredas, (36%) of the woredas in the zone, namely moyale, yabello, dhas, arero and teltele are currently getting support from the one wash program. hence, the aspirations of the program and the global and moti mosisa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 37 nation resources channeled towards this program are some of the essential prospects identified by the study. 4. conclusions and recommendation the study assessed the borena zone pastoralist communities’ access to sanitation service where the focus was given to latrine coverage and hand washing habit. the study found out that all types of household latrine coverage in the zone is around 72 percent. however improved latrine coverage is only 1.2 percent as most latrines in the area are tradition unimproved pit latrines. the remaining significant number of households does not have access to latrine mainly due to their frequent movement from one place to another in search of water and grazing land, lack of money, and lack of knowledge of the importance of sanitation practices. meanwhile, poor water supply, property of the soil in the area, lack of qualified manpower, habit of open defecation were the impediments lagging the status of improved sanitation service. while, health extension program, the availability of developmental actors, one wash program and the preventive health policy of the country were found to be the untapped potentials available to improve the sanitation service. in order to enhance the status of sanitation, tackle the challenges and tape the untapped prospects, the following recommendations are forwarded. firstly, as the level of sanitation related awareness is impressive in some kebeles, there exist relatively poor performances in some others. therefore, the best practices of the best performing kebeles should be scaled up to the other areas. secondly, the woredas and kebeles sanitation related record keeping and data availability system was very poor. unless the data is properly recorded and used as a base for decision making, the efforts for access to water and improved sanitation would not be succeeded. therefore the local governments should carefully and accurately store sanitation related data. thirdly, the primary stakeholders of sanitation at local government level are two offices-water and energy bureau and health bureau. thus, these two offices need to have qualified human resource with adequate materials and facilities in order discharge their duties. however, the observation made and the empirical fact in the study area is contrary to this premises. therefore, due attention should be given to fill vacancies by qualified human resource, and train and develop the capacity of the current staff. reference abrha tesfay (2015). a short report on the adoption of road side water harvesting technology as a means of climate change adaptation in afar pastoral areas gebru, g., desta, s., and coppock, d.l. (2004). pastoralism in ethiopia and the policy institute (ilri), addis ababa, ethiopia. report produced by the pastoral risk management; proceedings for a meeting held 15 august, 2003, at the international livestock research http://www.monitor.upeace.org/innerpg.cfm?id_article=821 [accessed, 27 july 2011]. ministry of health (2011). national hygiene & sanitation strategic action plan for rural, per-urban & informal settlements in ethiopia, addis ababa ethiopia, joint monitoring program (2015). progress on sanitation and drinking water 2015 update and mdg assessment, united states of america roger blench (2001). you can’t go home again’ pastoralism in the new millennium, london. fareh (2011). opportunities and challenges in implementing poverty reduction policies in pastoral communities: a case study from the somali regional state, ethiopia. thesis presented to the higher degree committee of asia pacific university in partial fulfillment of the requirements for the degree of master of science in international cooperation policy. water supply and sanitation collaborative council (nd) http://wsscc.org/wpcontent/uploads/2016/04/vision-21-a-sharedvision-for-hygiene-sanitation-and-water kothari, c.r. (2004). research methodology: methods and techniques. new delhi; new age international (p) limited, publisher. valerie curtis, sandy cairncross, raymond yonli (2001). domestic hygiene and diarrhea-pinpointing the problem; journal of tropical medicine and international health, 25 dec 2001 unicef (2013). sanitation fact sheet for world toilet day. http://www.monitor.upeace.org/innerpg.cfm?id_article=821 http://wsscc.org/wpcontent/uploads/2016/04/vision-21-a-shared-vision-for-hygiene-sanitation-and-waterhttp://wsscc.org/wpcontent/uploads/2016/04/vision-21-a-shared-vision-for-hygiene-sanitation-and-water 10 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9(1), 2022 journal home page: www.ejssd.astu.edu.et astu research paper indigenous knowledge vis-à-vis development: the potential of gadaa system in industrial leadership development hailu beyecha deti1,, kassaye gutema jebessa2 1mechanical engineering department, school of mechanical, chemical & materials engineering, adama science and technology university, p.o. box: 1888, adama, ethiopia 2english department, school of humanities and social sciences, adama science and technology university, p.o. box: 1888, adama, ethiopia article info abstract article history: received 01 july 2021 received in revised form 18 december 2021 accepted 13 march 2022 the main purpose of this study was to scrutinize techniques in gadaa system that helped to sustain leadership development of the oromo society and its implication for industrial leadership development. the study was conducted using qualitative research method and exploratory research design. accordingly, data of leadership development practices in the gadaa system were gathered from key informants through focus group discussion, key informant interviews and non-participant observation. the data were analyzed thematically. the study revealed that there were different strategies within the gadaa system that helped to nurture the leaders perpetually so that they can manage the society and their resources properly. gadaa system has got different leadership development techniques such as traditional education, training, experience sharing, observation, practicing and creating a sense of competition among individuals. the gadaa system encompasses different institutions such as centers, parties, grades and structures of gadaa system that enabled the society to deal with various challenges, ensure good governance and enhance efficiency in management. moreover, the study revealed that the gadaa system has got check and balance system that is undertaken in both the forward and backward directions. thus, the researchers would like to suggest that the proposed technique of gadaa system could have a bearing on the improvement of work environment and thus it could potentially be used in tandem with modern day industrial leadership development techniques. therefore, the government and concerned stakeholders should customize the important technique of gadaa system with regard to industrial leadership development for ensuring good governance and shaping the behavior of workforce in carrying out their roles and responsibilities properly. keywords: indigenous knowledge gadaa system gadaa leadership leadership development 1. introduction a number of scholars have conducted studies on the gadaa system of oromo people. among them, the prominent scholar is asmerom legese (1973; 2006) who described gadaa as an african democracy and as one of the most informative breakthroughs in the evolution of mankind. similarly, donald levine (1974) noted that gadaa is "one of the most complex systems corresponding author, e-mail: beyechahailu@yahoo.com https://doi.org/10.20372/ejssdastu:v9.i1.2022.384 of social organization ever devised by the human imagination". assafa jalata (2012) underscored that gadaa represents "the totality of oromo civilization”. marko bassi (2005) also described gadaa as the system of generational classes through which specific activities and social responsibilities are associated with each class. http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i1.2022..... hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 11 considering the symbolic significance of gadaa for the oromo as well as its structural innovations, researchers in law, indigenous studies and panafricanism have been exploring how the system could be utilized in the 21st century. for instance, a research by zelalem tesfaye (2012) entitled "ethiopia: when the gadaa democracy rules in a federal state" explores how the system could be integrated with the contemporary federal structure of ethiopia, serving as a governance mechanism for the oromia national regional state. he analysed that the techniques of gadaa system whereby consensus is reached through dialogue is unique but firmly rooted in western democratic norms, and thus well-suited to adoption within ethiopia's federally structured democracy. according to dessu dulla (2011), the borana rely on water wells that are guided by an indigenous harvesting knowledge, management system, property rights arrangements and conflict resolution under the gadaa institution for centuries. the appropriation of scarce natural resources, like water, requires robust management and conservation for present and future generations. in connection with this, marko bassi (2005) noted that the borana refer to their own culture and norms as ‘aadaa booranaa’ (the culture of the borana) that helps to manage and properly use natural resources (pasture, water, etc.). furthermore, efa tadesse (2018) asserted that gadaa values and practices can have relevance in cultural development, social development, economic development and environmental protection and any other development of the society. according to dereje hinew (2012), the gadaa system provides a socio-political framework that institutionalizes the relationship between seniors and juniors among the members of the gadaa grades so that the members can develop a consistent and stable sense of self and others. additionally, habtamu disasa (2017) reiterated that leader and leadership development is a lifelong process wherein individuals are made to develop general gifts of leadership and learn knowledge, skills, and attitudes of leadership both individually and in groups before they assume power in the gadaa system. similarly, solomon emiru (2017) claimed that gadaa system is a comprehensively guided, crafted and nurtured system of traditional administration under the superb wisdom of the ancient oromo people. thus, the gadaa system is extremely broad and comprises of all aspects of life like religion, politics, economy and culture of the oromo people. as it reflects virtually every aspect of human experience, it is believed that there are many lessons to be learned if people strived to inculcate the principles of the gadaa system in modern administration. it has been underscored by scholars like zelalem tesfaye (2012) and assefa jaleta (2012), the gadaa system nurtures every citizen with wisdom and skills to overcome challenges and manage resources properly. the scholars have also made it evident that the gadaa system also encourages people to be productive citizens by creating a sense of competition among them. furthermore, according to tesema ta’a (2016), the gadaa system as a form of indigenous knowledge helps to perpetuate peaceful coexistence through conflict resolution, youth empowerment, natural resource management and good governance. it is often reported that although ethiopia has got a lot of peculiar indigenous knowledge and skills, there is reluctance or even resistance to make use of these skills in tackling the challenges facing the country. in this regard, the aspect of gadaa system that has not attracted much attention appears to be its potential contribution to industrial leadership development in ethiopia. thus, it could be argued that the gadaa practices seem to correspond with modern leadership techniques that have helped in industrial leadership development. the researchers would like to argue that given its unique innovative structures, the gadaa system has got institutional experiences pertaining to practices and strategies that could be worth analyzing in light of present-day industrial leadership development. moreover, according to scholars like shimelis legesse et al. (2018), israel bekele et al. (2017), wolde shiferaw et al. (2020) and tesfaye teshome (2018), the motivation and commitment of workforce in their work place were very low in ethiopia. this could possibly be attributed to the lack of motivational techniques and mannerisms in system of leadership among other things. to this end, it is compelling to revisit the industrial leadership development system so as to seek ways of motivating the workforce by using indigenous techniques. as a result, exploring indigenous hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 12 knowledge of the gadaa system as a potential remedy seems to be a viable option. thus, this study was meant to explore the techniques of gadaa system with the view of determining their potential implication on enhancing industrial leadership development in modern industrial development. 2. method the study principally focused on qualitative research method and exploratory research design to find out techniques in the gadaa system that were used for mobilizing the community to be effective in productive endeavors. relevant data were gathered by using focus group discussion (fgd) and key informant interview (kii) from the informed practitioners of gadaa system such as gadaa leaders, gadaa writers and senior elders who have got the wisdom of gadaa system. the informants of the study were sampled by using snowball sampling technique. in addition, nonparticipant observation was used to collect relevant data of gadaa system for dealing with industrial leadership development. the process of the study was such that firstly, the practitioners were informed about the intention and scope of the study whereby they agreed to comply with the researchers' demands. afterwards, a common consent has been obtained authorizing the permission to go ahead. finally, the collected data had been transcribed and compiled for analysis by using voice records and field notes. the organized data were thematically (inductively) analyzed by maintaining the original descriptions of the voice records and field notes. the overall data analysis and collation processes were iterative in that involved summarizing the data and interpreting their meaning in such a way that the results could be drawn. 3. results and discussion 3.1.strategies for social organization in the gadaa system according to the key informants, the oromo were continuously organizing themselves from time immemorial using different practices of gadaa system. these practices include the centers, parties, grades and structures of gadaa system. 3.1.1. centers of gadaa system as stated by the key informants, the oromo organized themselves according to the centers of gadaa system, which are located at every corner of oromia. they centers are: gumii gaayyoo, me'ee bokkoo, odaa roobaa, odaa nabee, odaa bultum, odaa bisil, odaa bulluq, odaa dooggii and odaa hullee that are located at borana, guji, bale, east shoa, west hararge, west shoa, horro guduru wollege, ilu abbaa bor and jimma respectively. moreover, the centers of gadaa system are considered as holy places wherein the oromo held gadaa assembly to amend and enforce new laws. the informants made it evident that the oromo have further reorganized and added new centers at karrayu, matakal and wallo for the practice of gadaa leadership and administration. moreover, the execution of gadaa system (for instance, irreecha celebration) was expanding globally as it is being held wherever the oromo and their alliances live. this shows that the oromo organize themselves in new frontiers so as to practice their tradition. the establishment of new centers in the vicinity of certain groups was made to help them apply the gadaa principles for managing their livelihood and leadership development. 3.1.2. parties of gadaa system furthermore, the oromo organized themselves according to the five parties of gadaa system that have different names among sabbo gona, sikko mando, macca-tulama, ittu humbana, and rayya asabo. based upon the naming of macca-tulama, the parties were named as birmaji, horata, michile, dulo and robale. according to the key informants, any male oromo should belong to one of the five parties of gadaa system. the member of these parties should come to the power every eighth year in a rotational (or cyclic) manner. according to the principles of the gadaa system, there are no competitions between the parties to assume power as the parties take power consecutively every eighth year. however, there is competition among the members of every party to take power based on their experience and performance mainly at three gadaa grades prior to gadaa grade where they assume power. these are foollee from 16 24 years, kuusaa from 24 32 years and raabaa-doorii from 32 40 years of age. this implies that the gadaa system had enabled the oromo to practice a multi-party system with the proper allocation of clear time for taking power and properly leading and managing the society. hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 13 3.1.3. grades of gadaa system the finding revealed that the oromo organize themselves according to the eleven grades of gadaa system with their corresponding age ranges even if the age of the members varies. they are dabballee (d) (0 – 8), gaammee-xixiqqaa (gx) (8 – 16), gaammeeguguddaa (gg) (16 – 24), kuusaa (k) (24 – 32), rabaadoorii (rd) (32 – 40), gadaa (g) (40 – 48), yuuba 1ffaa (y1) (48 – 56), yuuba 2ffaa (y2) (56 64), yuuba 3ffaa (y3) (64 – 72), gadaamoojjii (gm) (72 – 80) and jaarsa-qululluu (jq) (above 80) years. the members of every grade gain particular social, economic and political privileges based on the eight-year increments in the gadaa hierarchy. the first five gadaa grades (from dabballee grade up to raabaa-doorii grade) are generally the periods of learning, training, development and military service in addition to shouldering some economic activities. the remaining five gadaa grades (from gadaa grade up to gadaamoojjii grade) are the periods of educating, leading, advising, monitoring, and taking social, political and economic roles and responsibilities. the final grade, jaarsa qululluu is a stage at which one has to be cared for in the cycle of gadaa system as that of the childhood. as such, the gadaa system instils the principles of leadership into the youth so that they can have a good mind set for properly executing respective duties and responsibilities at different points in their lifespan. additionally, the roles and privileges of every grade of gadaa system have been demonstrated in figure 1. figure 1: the continual change of gadaa grades with their roles and responsibilities as it can be observed from figure 1, the role of a person increases along with increment of age until one completes the stage of abbaa gadaa. at the beginning, the new generations are taken care as they are introduced to principles of the gadaa system. as they reach the stage of gadaa, they take over the decision making process and presiding over the issues of the society. however, after the execution of the stage of gadaa, the roles and responsibilities decrease gradually. this system will help to delineate the roles that a person is supposed to execute. in other words, the older generation will gradually withdraw from decision making pertaining to the major events of the society and resort to giving advices and training the more energetic and powerful new generation. 3.1.4. administrative structures of gadaa system the informants also affirmed that the oromo organize themselves according to the administrative structures of gadaa system. these administrative structures consist of the nine gadaa leaders from among the same batch. these are abbaa gadaa – one presiding over the gadaa, abbaa bokkuu – one in charge of holy sceptre, abbaa muudaa – one in charge of anointment, abbaa caffee – one in charge of gadaa assembly, abbaa alangaa – one in charge of prosecution, abbaa seeraa – one in charge of law, abbaa sa'aa – one in charge of economy, abbaa duulaa – one in charge of military and abbaa maatii – one in charge of social affairs. these gadaa leaders have full responsibilities to govern the oromo people politically, economically, socially, culturally and spiritually for eight years of their tenure. moreover, there are also supportive administrative units of gadaa system such as abbaa raagaa (one in charge of forecast), abbaa dubbii (spokesperson), abbaa murtii (one in charge of resolution), abbaa faajjii (one in charge of gadaa symbol/flag), abbaa malkaa (one in charge of the riverbank), abbaa tulluu (one in charge of mountains), abbaa qaalluu (one in charge of the hereditary spirit), and abbaa dhugaa (father of truth or god). as it can be observed from figure 2, gadaa system has its own structure that helps the development of sound trust and credibility between the gadaa leaders and the society based on its principles and the belief that they have on the creator (abbaa dhugaa). furthermore, one could realize that there a number of structures for hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 14 figure 2: the structure of gadaa system dealing with different types of issues. the informants have opined that respecting the norms and abiding by the principles of gadaa system strengthens the cohesion among the oromo. according to the key informants, there are additional administrative units or clusters among the borana. these administrative units or clusters help to oversee the proper management of the society at lower level, middle level and higher level of management. these units or clusters range from the lowest units of family which is led by abba warraa to the highest unit representing the entire borana which is led by abba gadaa. these clusters include: warra (family), shanacha (homestead), ollaa (settlement), reera (community), dheeda (district), gadaa (the entire borana) and dhugaa (truth). these clusters are led by abbaa warraa (head of family), abbaa shanachaa (head of homestead), abbaa ollaa (head of settlement), abbaa reeraa (head of community), abbaa dheedaa (head of district), abbaa gadaa (head of gadaa borana) and abbaa dhugaa (father of truth – the creator), respectively. this implies that there are different levels of leadership development and experience sharing on ways of managing resources from family level to the highest level. figure 3: the administrative units or structures of borana oromo hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 15 figure 3 shows that the boranas have got an administrative structure that helps to inculcate the principles of leadership into the young generation so that they learn how to solve the challenges of the society from the lower management level to the top management level. 3.2.strategies for social development in the gadaa system in the gadaa system, every individual is nurtured and developed gradually through different educational techniques so that they become effective leaders. the oromo conduct these didactic techniques phase by phase according to their importance and level of difficulty from the childhood (dabballee) grade up to the administrative (gadaa) grade under the main supervision of abbaa maatii and abbaa gadaa. the techniques are: ‐ traditional education: the elderly (from gadaa grade up to gadaamoojjii grade) usually offer traditional education through wit-improving activities such as riddles, songs, proverbs and folksongs so as to enforce the right type of attitude; ‐ training: the elderly (from gadaa grade up to gadaamoojjii grade) usually offer training to the new generation on specific activities such as farming, cattle rearing, riding, storytelling, etc. the gadaa leaders give anecdotes to help the youth get acquainted with the desired skills and attitudes; ‐ experience sharing and observation: the youth (from dabballee grade up to raabaa-doorii grade) given the opportunity to observe the manner in which the gadaa leaders handle different situations be it in economic affairs, social or environmental endeavours; ‐ practicing: what is so peculiar about the gadaa system is that it does not just expose the youth (from dabballee grade up to raabaa-doorii grade) to merely observe the skilled ones manoeuvring things but it also renders opportunities for the youths to practice and internalize the activities. as such mainly the abbaa maatii and abbaa gadaa coach the youth to make sure that the principles have been recited well through practical exercises and cases; ‐ competition: competition and rewarding conducted for improving and assuring the performance of individuals based on their stage from the childhood (dabballee) grade up to the administrative (gadaa) grade. based on the different techniques employed in the gadaa system, one can realize that the gadaa system enabled individuals to explore their potential and maximize their capacity through experiential learning, training and competition. moreover, the oromo were capacitating themselves individually or in a team form so that the next leaders of the society could be selected based on the track record of their performances in every grade level prior to the gadaa grade (40 – 48 years). this implies that the oromo amass potential management skills and capacities through continuous learning and improvement. this notion corresponds with david and lisa’s (2015) notion that promoting experiences, interventions and interactions are the main factors that enhance leadership development process. 3.3.strategies for social administration in the gadaa system there are different practices and concepts of gadaa leadership practices. in connection with this, the informants noted that there are two types of leadership (administrative) practices in the gadaa system. these are: ‐ individual leadership at which an individual leads himself and his family by using the concept of gadaa norms and laws. additionally, the informants added that an individual with good experience and performance may also lead her/his surrounding society as well, and ‐ group leadership at which a group of persons known as gadaa leaders (abbootii gadaa) collectively lead the society – the oromo at large. the key informants also added that any problem encountered should be solved by using different mechanisms (such as jaarsummaa, gumaa and araara) with common consensus and full agreement in the gadaa system. this shows that the gadaa system enables the oromo to practice management through individual and collective decision-making processes. in the gadaa system, there is a process of holding continuous hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 16 discussion so as to reach a unanimous decision. gadaa leaders lead the society through power sharing, and check and balance system. the hierarchy of the leadership varies from lower management level of family to top management level (abbaa gadaa) that leads the oromo at large. moreover, a typical point the informants raised was that the gadaa system has got a code of conduct known as safuu – a principle of morality that people can abide by to live harmoniously. safuu serves as a code of conduct whereby anybody who violates the rules of gadaa system will be alienated which will make the person devoid of any services from the society. the notion of leadership development in the gadaa system also corresponds with david and lisa’s assertions whereby they highlighted the development of leadership in individuals and teams (david and lisa, 2015). furthermore, habtamu disasa, who made extensive studies on leadership development in the gadaa system noted that leadership development is a lifelong process wherein individuals and groups can practice before they assume power (habtamu disasa, 2017). furthermore, the oromo live harmoniously by observing their cultures and values (aadaa and duudhaa). the oromo are administered and led by the gadaa leaders according to the norms and laws (heera and seera) of gadaa system. the norms and laws were generated from the oromo cultures and values with common consensus at gadaa assembly. thus, the administration and leadership of the oromo is a cyclic process that should be continuously updated. figure 4: the cyclic nature of gadaa administration figure 4 shows that the interconnections between the oromo, gadaa leaders, oromo cultures, values, oromo norms and laws are very strong so as to ensure the proper functioning of every individual in the society in a holistic approach. this has also been confirmed by habtamu disasa who stated that knowledge and practices of leadership development is ingrained into the belief and value system of the community (habtamu disasa, 2017). moreover, performing forward and backward monitoring system is the key technique in the check and balance of gadaa leaders. thus, the foollee, kuusaa and raabaa-doorii grades try to challenge gadaa leaders by continuously voicing their disapproval and criticism in the form of songs. the yuuba i, yuubaii, yuuba iii and gadaamoojjii grades also try to check gadaa leaders by guiding, advising, enforcing and even refusing to accept their decisions in the society. figure 5: forward and backward monitoring system of gadaa administration hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 17 figure 6: proposed technique of gadaa system as it can be observed from figure 5, gadaa leaders are under a continuous criticism and appraisal by both their juniors and seniors of gadaa grades through check and balance. moreover, figure 5 presents the iterative processes of evaluation that have helped the gadaa system to remain intact through generations. the figure also shows the dynamics of interaction between different gadaa grades that have helped the gadaa system to evolve. the interactions between the different actors are meant to inculcate the new generation with the right and desired type of skill and attitude at the different stages of gadaa system. it also enables the youth to realize the code of conduct for dealing with different social events and circumstances that help them to become the next leader and/or manager of the society at their gadaa grade. 3.4.proposed technique of gadaa system for industrial leadership development based on the analysis made, the researchers would like to suggest the following alternative technique of gadaa system for possible adoption in modern industrial leadership development process. figure 6 shows that the workforces have to be organized according to their years of service, experience and performance as widely seen in the gadaa system. afterwards, they need to be developed through continuous education, trainings, experience sharing, observations, practicing and competition on specific activities and thereby rewarding the best performers. moreover, activities need to be conducted transparently through good governance by using proper power sharing, check and balance by organizing platforms for the forward and backward monitoring system in order to ensure sustainable development in industries. 4. conclusion the main purpose of this study was to propound the potential strategies of gadaa system in enhancing industrial leadership development in ethiopia. the findings of this study made it evident that the gadaa system has got effective administrative structure that could help to ensure good governance and leadership development. thus, the strategies of gadaa system could help in nurturing the youth to acquire skills of management. moreover, the strategies in the gadaa system are used for properly organizing, developing and administering the oromo people. what is more is that the gadaa system has got practical experiences on human development techniques such as traditional education, training, experience sharing, observation, practicing and creating a sense of competition among individuals. on the top of that, the gadaa system has got institutions such as gadaa centers, parties, grades and structures that enable the society in dealing with various challenges, ensuring good governance and enhancing efficiency in management. thus, based on the findings of the study, it can be concluded that the proposed potential technique of gadaa system can possibly be used as an alternative industrial leadership development technique in tandem with modern day techniques. finally, the researchers would like to argue that as gadaa system has been proven a panacea to almost every aspect of life, the government and concerned stakeholders should customize the valuable technique of gadaa system. hailu beyecha and kassaye gutema ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 18 acknowledgment the authors would like to thank adama science and technology university for their concern to support the accomplishment of this study by providing financial and material supplies. additionally, the authors would like to thank all the senior elders, gadaa writers and gadaa leaders who have participated in the fgd and ki interview. reference asafa jalata. (2012). gadaa (oromo democracy): an example of classical african civilization. journal of pan-african studies, 5(1): 126-152. asmarom legesse. (1973). gada: three approaches to the study of african society. new york: the free press. asmarom legesse. (2006). oromo democracy: an indigenous african political system. asmara: the red sea press, usa. bassi, m. (2005). decisions in the shade: political and juridical processes among the oromo borana. david, v. d. and lisa, d. (2015). leadership development: an outcome-oriented review based on time and levels of analyses. annu. rev. organ. psychol. organ. behav., 2: 133–56. dereje hinew (2012). history of oromo social organization: gadaa grades based roles and responsibilities. science, technology and arts research journal, 1(3):88-96. dessu dulla. (2011). culture in sustainable development thinking: an indigenous water management system: the case of borana people, master thesis. efa tadesse. (2018). relevance of gadaa values and practices in current development. arts social sci j., 9(3), 1-5. habtamu disasa. (2017). indigenous knowledge and practices of leader and leadership development in the gadaa system of borana oromo community of ethiopia, doctoral dissertation. israel bekele, kifle w, tigist d, fantahun w. (2017). organizational commitment and its predictors among nurses working in jimma university specialized teaching hospital, southwest ethiopia. journal of primary health care, 7(1): 1-8. levine, d. (1974). greater ethiopia: the evolution of a multi-ethnic society. shimelis legesse, mesfin beharu, elias ali and yohannes ejigu (2018). motivational status and associated factors among jimma university specialized hospital health professional, south west ethiopia. quality in primary care, 26(2): 5363. solomon emiru. (2017). harnessing gadaa system as a black covenant in modern constitutional administration: appraisal of prospects and challenges. sociology and anthropology, 5(1): 52-62. tesema ta’a. (2016). the gadaa system and some of its institutions among the booranaa: a historical perspective. ethiopian journal of the social sciences and humanities, 12(2): 81-97. tesfaye teshome. (2018). factors affecting employee motivation in ethiopian roads authority, masters thesis. wolde shiferaw, eminent negash, aregu asmare and shimekit kelkay (2020). effects of employee motivation on organizational performance at ethiopian telecom south west region jimma. prizren social science journal, 4(2): 3040. zelalem tesfaye. (2012). ethiopia: when the gadaa democracy rules in a federal state: bridging indigenous institutions of governance to modern democracy, master thesis, may. 109 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu review paper ecosystem services of exclosures in ethiopia: a review meseret habtamu, eyasu elias centre for environmental science, college of natural and computational science, addis ababa university, p.o. box 80119, addis ababa, ethiopia article info abstract article history: received 04 may 2021 received in revised form 20 august 2020 accepted 03 sept. 2021 exclosures are areas that are closed-off from human and domestic animal disturbances to allow regenerating vegetation to reduce further land degradation and enhance rehabilitation. exclosures have different ecosystem and economic benefits. the objectives of this systematic review were to appraise research findings and to summarize the most important literatures on the role of area exclosures for ecosystem services in ethiopia. after several screening steps using inclusion and exclusion criteria, only 33 studies qualified for qualitative analysis. different studies indicated that exclosures have ecological and economic importances for the area and local communities. the practice of area exclosures is becoming popular and about 7 mha of degraded area has been rehabilitated between the years 2011 and 2014. moreover, a total of 15,404.6 ha of land have been established as area exclosure in different regions of the country from the year 2015-2019. a total of 1.4 mha degraded lands were rehabilitated using area exclosures until 2019. exclosures play vital role to restore native vegetation composition, richness, diversity, rehabilitation of degraded lands, reducing soil erosion, recharging ground water, increase soil and above ground biomass. in addition it provides considerable fodder access for livestocks and efficient to increase financial income for households. keywords: economic benefits ecosystem services exclosures 1. introduction natural resources are getting depleted at a faster rate in different regions of ethiopia. there are various driving forces for natural resource loss. deforestation has been a major problem for quite a long time. some of the consequences are decline or loss of biodiversity, degradation of land and water bodies, possible negative effects on the local, regional and global climatic conditions as well as negative impacts on the welfare of human beings (berry, 2003; gashaw et al., 2015). the drivers of deforestation and forest degradation include population growth, agricultural expansion, resettlement, land tenure, free grazing, forest fires, pests and diseases, and unwise utilization (yigremachew et al., 2015). the  corresponding author, e-mail: ethiomisgie@gmail.com https://doi.org/10.20372/ejssdastu:v8.i2.2021.375 forest degradation in ethiopia is closely linked to the ongoing population growth (reusing, 2000; zeleke and hurni, 2001; dessie, 2007; mulugeta and habtemariam, 2014). forest and land degradation is a serious problem worldwide, particularly in developing countries. approximately one billion people live in degraded areas, which represent 15% of the earth’s population, and one third of the world’s population is considered to be affected by land degradation (sabogal et al., 2015). deforestation over the period 1980-1990 reached 8.2% of total forest area in asia, 6.1% in latin america and 4.8% in africa (contrerashermosilla, 2000). despite a http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i2.2021.375 meseret habtamu and eyasu elias ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 110 number of initiatives to stop forest decline, the world continues to lose some million hectares of forests every year at a regional level. south america suffered the largest net loss of forests between 2000 and 2010 about 4.0 million hectares per year followed by africa, which lost 3.4 million hectares annually (fao, 2010). deforestation, soil erosion, and land degradation are serious problems in ethiopia. the clearing of forests has been a long historical process in ethiopia and it continues at a conservatively estimated rate of 62,000 ha per year (berry, 2003). this is mostly converted into cropland with greatly reduced vegetative cover, accelerated soil erosion, also change the hydrological pattern of run off, reducing infiltration and increasing stream flow during and after rain (berry, 2003). in addition to deforestation, population growth has led to a number of problems related to inappropriate cultivation, overgrazing, soil erosion, soil fertility decline, water scarcity, lack of pasture, and a fuel wood crisis. betru (2003) cited in abera et al. (2016) stated that sustainable conservation and utilization of the remaining forest resources and rehabilitation of the degraded would provide economic, social and ecological benefits. this requires designing economically feasible, socially acceptable and ecologically viable management and conservation strategies. in this regard, the government of ethiopia has initiated a number of projects including soil and water conservation and the establishment of area exclosures to stop further land degradation. the main actors include governmental and non-governmental agencies and the private sector. recent approaches attempt to combine participatory and decentralized approaches that include engagement of ngos and the private sector (eshetu, 2006). seven million hectares of degraded area has been rehabilitated using area exclosure until 2014 in the country (ebi, 2014). a report by tigray regional bureau of agriculture and rural development (2013) indicates that approximately 1,288,445 ha of land in the region is managed through area exclosures as stated in yigremachew et al. (2015). establishing exclosure is a promising practice for rehabilitation of degraded lands started in different parts of ethiopia (emiru et al., 2006; yayneshet et al., 2009). it has been widely promoted, especially in the northern and central highlands of ethiopia. thus, general objective of this review is to assess research findings and to summarize the most important literatures on the role of exclosures for ecosystem services, economic benefits and the challenges in ethiopia. 2. methodology in order to achieve the aim of the review paper on the role of exclosures for ecosystem services, the collected data were extracted and total of 33 secondary data were used. additional data were collected from different reports of food and agriculture organization (fao), ministry of agriculture (moa), and ministry of environment, forest and climate change (mefcc). the first step was defining key terms by reviewing the final verified title and this was in turn, used to choose appropriate databases. terms were then combined in relevant categories using boolean logic operators (“or” and “and”). the search procedure was tested by the chosen database: science direct; and then the final algorithm that retrieved the highest proportion of all known relevant articles were selected: the search was done from october 10 to 30, 2020. 3. results and discussion 3.1. exclosures in ethiopia exclosures are areas that are enclosed to allow restoration and rehabilitation of degraded lands by natural means. the context and definition of area exclosures vary from country to country (abera et al., 2016). in the ethiopian context, it can be defined as the degraded land that has been closed-off or otherwise protected from human and domestic animal disturbances to allow regenerating native vegetation (emiru et al., 2017; wolde et al., 2017). most parts of ethiopia are generally regarded as heavily deforested, natural forest has been decreasing at an alarming rate (cheng et al., 1998). to ameliorate this situation, different initiatives and strategies have been implemented to increase the forest area in ethiopia. in response to the 2011 bonn challenge, ethiopia has committed to restoring 15 million ha of degraded forest. in the climate resilient green economy (crge) document, the government has set afforestation and re-forestation targets to cover 3 million ha of land by 2030 (fdre, 2011). meseret habtamu and eyasu elias ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 111 3.2. ecosystem services of exclosures in ethiopia ecosystem services are the benefits people obtain from ecosystems. these include provisioning services such as food and water; regulating services such as flood and disease control; cultural services such as spiritual, recreational, and cultural benefits; and supporting services, such as nutrient cycling, that maintain the conditions for life on earth (millennium ecosystem assessment, 2005). exclosures are ecologically and economically advantageous (wolde et al., 2007). it could contribute to both peoples’ livelihood and environmental quality (temesgen, 2018). in addition, area exclosures have contribution to the 3 pillars of sustainable development; environmental benefits (increased vegetation cover, decreased downstream soil erosion, increased biodiversity and improved microclimate), economic benefits (sustainable fire wood from fallen branch, grass harvesting through cut and carry, and bee hiving) and social benefits (land users right secured, increased community institution rights, awareness creation and knowledge transfer). some of the major ecosystem services of area exclosures in ethiopia are discussed below. 3.3. biodiversity conservation the practice of exclosures has become popular in most regions of ethiopia. for example in tigray region (emiru et al;, 2006; haile, 2012; mastewal et al., 2006; aynekulu et al., 2009; wolde et al., 2009; wolde and masetewal, 2013; samson et al., 2017; mekuria et al., 2018), oromia region (meron 2010), amhara region (kibret, 2008; getachew and malke, 2015; abera et al., 2016; belay and eyasu, 2017; wolde et al., 2017), snnp region (ango et al., 2014; yirdaw et al., 2017) and central rift valley (mohammed et al., 2015) have shown that exclosures are becoming a common conservation practice in different regions of the country. different studies indicated that establishment of area exclosures enhanced biodiversity, floristic composition, structure and density in different regions of ethiopia. a research conducted in southern wello by kebrom (1998) cited in kibret (2008) pointed out that establishment of exclosures improved composition, density, richness, and diversity of woody species in comparison to open adjacent sites. similarly wolde et al. (2018) in aba-gerima watershed of amhara region demonstrated that after four years of establishment, the exclosure displayed higher plant species richness and diversity compared to the adjacent grazing land. this is known that increased vegetation density in exclosures results in increased infiltration and higher transpiration, which in its turn triggers vegetation restoration through increased biomass production (nyssen et al., 2007). different studies confirmed that exclosures have great contribution for biodiversity conservation (table 1). a study by meron (2010) showed that the stand density of all woody plants in the old and young exclosures was 1022 ha-1 and 587 ha-1 respectively, however, in the respective open grazing area the density was 180 ha-1. similarly, emiru et al. (2006) reported that 27 woody species representing 18 families were observed in exclosures and 14 woody species representing 12 families were recorded in open area. in addition, angassa et al. (2010) reported that herbaceous biomass was more than twice as high compared to areas outside of exclosures. biophysical comparison of exclosures and adjacent free-access lands by (tefera et al., 2005) showed that above-ground woody species composition increased by 50%, whereas soil seed banks increased by 43% after table 1: diversity indices of woody species for enclosures and non-exclosures exclosure age no. of species in exclosure no. of species in open grazing land reference 2659 (individual trees) 746 (individual trees) (emiru et a l., 2007) 10221 180 (meron, 2010) 585 332 (ermias et al., 2009) 20 85 (woody species) 25 (woody species) (wolde, 2013) 93 41 (haile, 2012) 47 37 (kibret, 2008) 42 35 (mastewal et al., 2006) 7 20 13 (mamo, 2015) meseret habtamu and eyasu elias ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 112 exclosure. it has become a common phenomenon to observe acceleration of plant and animal diversity with time after the establishment of exclosures (eshetu, 2006). the success of exclosure depends largely on the time since closure, the original vegetation and past disturbance history (emiru et al., 2006). for instance the study by mastewal et al. (2007) indicated that the density of large wild mammals varied as of exclosures age. the composition of woody vegetation also depends largely on age of the exclosures establishment (tefera, 2001). similarly, mastewal et al. (2006) reported that the older exclosures had higher woody species density and diversity than the younger ones. for instance, the 29-year-old exclosure had 42 woody species and there were 35, 23, 21 woody species in the 22, 8 and 10-year old exclosures, respectively. there are evidences that suggest area exclosures are becoming promising alternatives to combat desertification and conserve biodiversity in completely degraded lands. species which had long disappeared from the exclosures in eastern tigray (e.g. olea europaea subsp. cuspidata and juniperus procera) re-appeared, densities and diversities of the flora (particularly grasses) and fauna increased, the level of soil erosion decreased, and even springs started to flow after exclosures were established (emiru et al., 2007). exclosures establishment is currently used as means to maintain biodiversity. kassa et al. (2017) reported that most northern highlands of ethiopia have more trees and woody biomass than 100 years ago, and this positive trend has also been observed in other parts of the country during the past three decades. 3.4. rehabilitation of degraded land establishing exclosures is considered advantageous since it is cheap, fast and productive method for the rehabilitation of degraded lands (tucker & murphy, 1997; emiru et al., 2006,). some of the degraded areas have become re-vegetated within just a few years, and it is strongly hoped that the current momentum of restoration of the vegetation would continue leading to rehabilitation of the degraded lands, which would in turn offer the desired socio-economic benefits as well as environmental services (wolde et al., 2009). area exclosures has become very common, especially in the highlands, due to the impressive improvement of productivity and reduction in soil erosion (moa, 2000). according to betru et al. (2005) as cited in meron (2010) in tigray region alone, a total of 262,000 ha have been closed until 2010. a study by wolde et al. (2018) at aba gerima watershed in north-western ethiopia which confirmed that exclosures could be one option for restoring degraded landscapes within short period of time. in tigray highlands, the establishment of exclosures has become an important measure to combat land degradation and restore vegetative cover. because of their high sediment trapping capacity, exclosures are a very efficient soil and water conservation measure. they accelerate fertile soil buildup and prevent important sediment loads from leaving the catchment or silting up water reservoirs (descheemaeker et al., 2006). vegetation rehabilitation through exclosures is competent measures for soil and water conservation, and alternative forms of land use to overcome erosion and deposition (fao, 2001). exclosures are supplemented with enrichment plantings of native and/or exotic species as well as soil and water conservation measures to speed up the recovery processes (eshetu, 2006). about seven million hectares of degraded area has been rehabilitated using exclosures between the years 2011 and 2014 (ebi, 2014) in ethiopia. according to moa (2019) report, starting from 2015 till 2019, a total area of 15404.6 ha rehabilitated in different regions of the country. 3.5. soil conservation and restoration exclosures have a significant positive effect on the restoration of degraded soils. it has effective role in improving soil nutrient content and properties. a study in northern highlands of ethiopia proved that exclosures showed higher total soil nitrogen (n), available phosphorus (p), and cation exchange capacity than the communal grazing lands (wolde and ermias, 2011). a similar study by gebregergs et al. (2019) illustrated that highest organic carbon, and total nitrogen were recorded in the 10 years of exclosures than open grazing lands. the higher soil organic matter content in exclosure can potentially improve the soil physical properties such as soil structure and total porosity (yimer et al., 2015). similar results were reported from exclosures established within the last two decades in the central highlands of ethiopia: an increase of 0.67% organic meseret habtamu and eyasu elias ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 113 matter, 8.85 mg kg-1 increase in available p, and 9.18 cmolc kg−1 increases in cec after 9 years of exclosure establishment (mamo, 2008) and 2.33%, 0.08%, 7.89 cmolc kg−1 increases in organic matter, total soil n, and cec, respectively, after 20 years of exclosure establishment (tsetargachew, 2008) cited in wolde and ermias (2011). establishment of exclosures is required to detect significant improvements in most of the investigated soil properties. a study that was conducted in douga tmbein woreda in tigray region indicated that soil loss from free grazing lands was 47% higher than the soil loss from exclosures (wolde et al., 2009). in addition a study by kibret (2008) in kallu woreda in southern wello confirmed that soil moisture percentage is higher in exclosure than in the open site, this could also be attributed to the higher organic matter accumulation. exclosures were effective in soil conservation, restoring degraded soils and increasing soil carbon in the highlands of tigray. the higher soil nutrients content and properties in all exclosures indicate the positive effect on the restoration of degraded soil (mekuria et al., 2011). 3.6. exclosures enhance biomass carbon stock area exclosures have great role to enhance biomass carbon stock. establishing exclosure on degraded lands leads to increased carbon absorption or sequestration (wolde, 2005; wolde et al., 2009). a study by gebregergs et al. (2019) in the semi-arid areas of tselemti district (northwestern tigray region) confirmed that higher aboveground carbon stock was recorded in 10 years exclosure and lowest on open grazing land. another study by samson et al. (2017) in tigray region demonstrated that exclosures showed higher soil carbon concentration, soil carbon stocks, and aboveground carbon stocks than the adjacent free grazing lands (figure 1). plant species diversity and aboveground biomass increased with exclosure age (wolde and mastewal, 2013). different studies proved this; for instance a study in tigray region of semiarid grazing systems showed that the mean aboveground biomass measured inside the exclosures was more than twice that of the adjacent grazed areas and more biomass was produced from the young than the old exclosures (tesfay, 2011). a similar study by yayneshet (2011) reported a twofold increase in aboveground biomass after eight years of exclosure establishment. the improvement in soil properties and nutrients is a key factor for the enhancement of biomass production in exclosures (wolde, 2005). the establishment of exclosures is a viable option to restore native vegetation composition and aboveground biomass (wolde and mastewal, 2013). figure 1: carbon stock (ton/ha; mean ± se) under the 5 and 10 years of grazing exclosures and open grazing lands (extracted from: gebregergs et al., 2019) (agc = aboveground carbon stock, bgc = belowground carbon stock, ghlc = grass, herb, and litter carbon stock and soc = soil organic carbon, and tc= total carbon). 3.7. socio-economic benefit of area exclosures exclosure land management can support to diversify the livelihood options of local communities, as most of the regenerated woody species are economically important, and once vegetation is restored, income generating activities can be integrated (mekuria et al., 2018). exclosures are boosting annual household income of local people (tefera et al., 2005). the existing wider implementation of exclosures in ethiopia especially in the high lands is related to the multifaceted benefits of exclosures (wolde et al., 2018). several previously degraded areas have regained forest vegetation via natural succession through exclosures (emiru et al., 2017). forest resources of ethiopia serve for economic, ecological and social purposes. forests contribute an estimated 4% to gdp through the production of honey, forest coffee, and timber. recent estimates indicate that about 26-30% of the total coffee production of the country originates meseret habtamu and eyasu elias ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 114 from wild and semi-managed coffee forests. the value of wild coffee is estimated 130 million usd/annum (mulugeta, 2012). the economic value of closed areas could be categorized as use and nonuse values (bedru et al., 2006). area exclosures directly or indirectly contributes to the increase of crop yields, fodder production and improvement of farm income (nyssen et al., 2007). a study by meron (2010) showed that on average a household share of thatching grass sells for 104 ethiopian birr annually in biyo kelala exclosure and 38 ethiopian birr in tiya exclosure (tefera et al., 2005). a similar study by asmamaw (2011) in kewot district (north shewa region) showed that enclosures provide considerable fodder access for livestocks and are efficient to increase financial income for households. the net present value of exclosures ecosystem services under consideration was about 28% (837 us$) higher than alternative wheat production indicating that exclosures are competitive to alternative land uses (wolde, 2013). for exclosures to continue playing their environmental conservation role, socioeconomic needs of local people is very important. a sustainable and socially fair harvesting system of the wood resources or a rotational grazing system initiates local people to have positive attitude towards exclosures (descheemaeker et al., 2009). the linking of exclosures with other natural resource management, soil and water conservation and livelihood diversification practices has been the biggest innovation that has contributed to the sustainability, acceptability and broader impact of the practice in terms of environmental, social and economic aspects in addition to climate change adaptation and mitigation benefits. for example, beekeeping has been linked to exclosures as the practice does not result in damage to it, while beekeeping provides an alternate income and contributes to resilience to climate change through livelihood diversification. this ensures that the practice of exclosures contributes to both climate change adaptation and mitigation (abenet et al., 2016). 3.8. challenges of area exclosures exclosure has been one of the strategies for rehabilitating the degraded hillsides and for soil and water conservation programs (betru et al., 2005). though area exclosures have multiple benefits, there are also challenges that hinder not to access their benefits effectively. the challenges differed from regions to regions. it has often been criticized for not offering communities with enough revenue to get out of poverty, as it is usually designed with the main purpose of protecting forests. the major challenges of area exclosures in most areas are conflicts among peasant associations for land, shortage of grazing land, uncontrolled grazing, weak bylaws and absence of exclosures guards/keepers (getachew and malke, 2015). in addition lack of national land use plan, poverty, landlessness and tenure insecurity are also challenges of area exclosures (kassa et al., 2017), lack of clear and negotiated benefit sharing mechanism, slow process of rehabilitation, poor soil, seed and seedling bank, moisture stress due to rainfall scarcity and erratic natural phenomena limit the survival of seedlings (emiru et al., 2017), and increased expectations of the community about economic benefits on exclosures became challenges (gebremedhin et al., 2000). conducting enrichment plantation of economically important plant species such as fruit trees and trees that can be used for fuel wood (e.g., acacia decurrens) could help improve the short-term benefits of the exclosure. allowing communities to harvest fruits and fuel wood can contribute to increasing their incomes and diversifying their livelihoods (abenet et al., 2016). 4. conclusion the major focus of the review paper was to investigate the different ecosystem and economic benefits of area exclosures in different regions of ethiopia and identify the major challenges. all the review articles indicated that exclosures have various ecosystem and economic benefits. it is a very suitable and in most cases a very essential practice for areas that are highly degraded and not very productive. exclosures are sources of wood for construction, and non-timber forest products. they also play an important role in conserving remaining soil resources and improving soil fertility. it improves soil fertility by augmenting soil nutrients from decomposed plant remains. it also limits nutrient loss from a site by controlling runoff (vegetation acting as a physical barrier to soil erosion). this eventually improves the capability of the land to support other vegetation types including exotic plantations. meseret habtamu and eyasu elias ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 115 area exclosures integrated with other natural resource and income generating activities such as soil and water conservation, promotion of wood saving and solar stoves, crop land management, grazing land management plans, agro-forestry, apiculture, fodder production and community capacity building show greatest success and sustainability. moreover, the studies showed that area exclosure is an intervention measure that boosts land productivity, biodiversity conservation and plays a key role in carbon sequestration. reference abenet, m., sebastian, g., & koen, j. 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(2001). implications of land use and land cover dynamics for mountain resource degradation in the northwestern ethiopian highlands. journal of mountain research development, 21(2): 184-192. 80 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper synthesis of silica supported iron oxide nanoparticles for hexavalent chromium removal from aqueous solutions jibril edris, neeraj k. gupta, enyew a. zereffa* school of applied natural science, department of applied chemistry adama science and technology university, p.o box 1888, adama, ethiopia *corresponding author, e-mail: enyewama@yahoo.com abstract iron oxide nanoparticles (nps) were synthesized by the chemical precipitation method using 1:2 ferric chloride hexahydrate (fecl3.6h2o) and ferrous sulphate heptahydrate (feso4.7h2o) precursors and ammonium hydroxide (nh4oh) precipitating agent. these nps were evaluated for their performance as adsorbents for hexavalent chromium ions (cr (vi)) in aqueous solutions. silicon dioxide gel (sio2) was also incorporated during synthesis to improve the adsorption characteristics of the nps. the nps (with out and with sio2 gel (iron oxide nps-sio2) were characterized by xrd and ftir spectroscopy. by xrd, it was evidenced that the iron oxide nps and iron oxide nps-sio2 adsorbents were mixed oxides of magnetite (fe3o4) and maghemite (γ-fe2o3) with small crystallite size of 13.5 nm and 12.8 nm respectively. the mixed oxides were formed as a result of the synthesis parameters and drying temperature at 1500c in air. the change of the black color of the just synthesized nps to orange brown also inferred the transformation of fe3o4 to γ-fe2o3. further evidence of mixed oxides is provided by the ftir analysis wherein the characteristic bands of γ-fe2o3 around 582 cm -1 and the distinct high-frequency shoulder in the proximity of 635 cm1 to 642 cm-1 are evidenced besides those of fe3o4.the effect of different parameters such as ph, cr (vi) ions concentration, adsorbent dose and contact time on the efficiency of adsorption showed that the iron oxide nps-sio2 adsorbent showed better performance for the removal of cr (vi) ions under acidic ph at room temperature compared to the iron oxide nps adsorbent. the maximum uptake of cr (vi) ions by the iron oxide nps-sio2 adsorbent increased from 80% to 96.5% by decreasing its initial concentration from 60 mg l-1 to 20 mg l-1 at optimum conditions. analysis of the adsorption isotherms of the iron oxide nps-sio2 adsorbent by the langmuir and freundlich models showed that the experimental data fitted well to the langmuir model suggesting monolayer coverage of cr (vi) ions mainly on the outer surface of the adsorbent. keywords: iron oxide nanoparticles, silica gel, magnetite, maghemite, adsorption. 1. introduction heavy metals are among the various life-threatening pollutants present in soil and aquatic bodies and endangering the health of humans (duruibe et al., 2007), animals (boyd, 2010) and plants (cheng, 2003). the global heavy metal concentration in various environments is increasing due to an increase in their use and the number of industries. most of the industrial wastewaters contain heavy metals such as cadmium (cd), lead (pb), zinc (zn), arsenic (as), cobalt (co) and chromium (cr) (duruibe et al., 2007), etc. among these heavy metals, cr mainly contaminates the water bodies through effluents from industrial activities such as electroplating, leather tanning, dying, mining and nuclear power plants (smith and ghiassi, 2006). cr (vi) is known to cause cancer and targets the respiratory system; kidneys, liver, skin, eyes and different regulatory authorities have developed http://www.ejssd.astu.edu/ jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 81 regulations and guidelines for cr to protect the public from potential adverse health effects. the occupational safety and health administration (osha) has established an 8-hour time-weighted average (twa) exposure limit of 5 mg of cr (vi) per cubic meter of air (5 g m-³) (us department of labor, 2009); the national institute for occupational safety and health (niosh) has recommended a 10-hour time-weighted average (twa) exposure limit for all cr (vi) compounds of 1 µgm-³ cr (vi) (niosh 2013); the u.s. environmental protection agency (epa) limits the maximum contaminant level of total cr in wastewater at 0.05mg l3 (acar and malkoc, 2004); and the world health organization (who) guideline regulates total chromium containing cr (iii), cr (vi) and other species of chromium to be discharged below 2 mg l-1 (who, 2004). a number of treatment methods for the removal of heavy metal ions from aqueous solutions have been reported such as reduction, ion exchange, solvent extraction, reverse osmosis, chemical precipitation, adsorption, biosorption and electrodialysis (odeh et al., 2015). most of these methods have certain disadvantages such as the production of large volumes of sludge, high cost of chemicals, increased concentration of dissolved solids in the effluent, high startup costs and low efficiency (samarghandi et al., 2015). adsorption, however, is recognized as an effective and economical process for a wide variety of applications, especially for the removal of heavy metals from wastewaters, the exception being one of the most widely used adsorbents, i.e., activated carbon, which is expensive and possibly non-cost effective in the treatment of large wastewater volumes (nadeem et al., 2006). however, the significant advantages of the adsorption technique are its high efficiency in removing very low levels of heavy metals from dilute solutions, easy handling, high selectivity, lower operating cost, minimization of chemical or biological sludge, and regeneration of the adsorbent (ozdes et al., 2011). this is why materials and structures such as nanoparticles (nps) as alternative low-cost adsorbents are being paid considerable attention. currently nps are used in wide range of applications, including shape selective catalysis, chromatographic separations, sorption of metal ions, enzyme encapsulation, in the fields of biotechnology and biomedicine for cell labeling and separation, magnetic resonance imaging (mri), enzyme and protein separations, targeted drug delivery and magnetic ferrous fluids hyperthermia. to date, many technologies, mainly co-precipitation (mahdavian and mirrahimi, 2010), microemulsion (drmota et al., 2012), thermal decomposition (sharma and jeevanandam,2012), hydrothermal synthesis (xin, 2012), microwave assisted (ahmed et al., 2013), sol-gel (huang and hu, 2008) and sonochemical synthesis (vijayakumar, 2000) has been applied and reviewed for the production of nps. application of nanostructures as adsorbents is valid for their use in other applications, requires particle stabilization and/or surface functionalization for good dispersion, particles suspension stability and no agglomeration in liquid media. such stabilizing agents should be economical and widely available. the aim of the present work was to synthesize iron oxide nanoparticles (iron oxide nps and iron oxide nps with the incorporation of silica gel (sio2) particles (iron oxide nps sio2), and evaluate their performance for the adsorption of cr (vi) ions in aqueous solutions. the sio2 gel was incorporated as a synergist to evaluate its contribution to the enhancement of adsorption since it is reported that the sio2 surface strongly binds fe (iii) and cr (iii) ions via surface complexation (oh et al., 2007). 2. materials and methods 2.1. materials all chemicals and reagents used for the experiments were analytical grades. ferric chloride hexahydrate (fecl3.6h2o, 99%, sigma aldrich, usa), ammonia solution (nh4oh, 25%), ferrous sulphate heptahydrate (feso4.7h2o, 98.8%, sigma aldrich, usa), general purpose silicon oxide gel (sio2, silica ar tm 40 63 microns (230 400 mesh), macron fine chemicals, usa), absolute ethanol (ch3oh, 99.8%, lobachemie, india), potassium dichromate (k2cr2o7, 99.9%, lobachemie, india), 1,5-diphenyl carbazide (1,5-dpc, c13h14n4o, 98%, lobachemie, india), nitric acid (hno3, riedel dehaen, germany), sulfuric acid (h2so4, riedel dehaen, germany), and hydrochloric acid (hcl, 35%, from riedel dehaen, germany). jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 82 2.2. methods 2.2.1. preparation of the nanoparticles 2.2.1.1. preparation of iron oxide nps the iron oxide nps were synthesized by modification of a co-precipitation method (sharma et al., 2009). in a typical experiment, the stoichiometric ratio 1:2 between the iron species, ferrous/ferric ions (fe2+/fe3+) was maintained. 6.0 g of fecl3.6h2o and 3.0 g of feso4.7h2o were dissolved in 100 ml distilled water with stirring for 3 minutes at 2000 rpm. after 3 minutes, 25 ml nh4oh 25% (precipitating agent) was added drop wise in 5-7 minutes. the reaction was continued for a further 30 minutes at a temperature of 90ºc; and the ph was maintained between 8 and 12 till a dark colored precipitate was formed. after stopping the reaction and magnetic field application, the reaction mass separated out into two phases: a clear aqueous phase on top and the consolidated precipitate at the bottom of the reaction vessel. the clear aqueous top phase was decanted and the black colored precipitate isolated by repeatedly washing with distilled water and centrifuging to remove excess chloride, sulphate ions and nh4oh until the supernatant became neutral (ph~7.0). the precipitate was further washed with c2h5oh and dried at 150°c for 2 hours to obtain the iron oxide nps. 2.2.1.2. preparation of iron oxide nps-sio2 1.5 ml (3 mol l-1) hcl solution was added into 13 g l-1aqueous sio2 gel suspension and stirred for 2 hours. after 2 hours, 50 ml serum was withdrawn and centrifuged, and the acid washed sio2 gel neutralized (li et al., 2011). thereafter, the sio2 gel was added to a 100 ml aqueous solution of 6 g of fecl3.6h2o and 3 g of feso4.7h2o while stirring at 2000 rpm. after 3 minutes of stirring, 25 ml nh4oh 25% (precipitating agent) was added drop wise in 5-7 minutes. the reaction was continued for a further 30 minutes at a temperature of 90ºc and the ph was adjusted till a dark colored precipitate was formed. after stopping the reaction and magnetic field application, the reaction mass separated out into a clear aqueous top phase and the consolidated black colored precipitate at the bottom of the reaction vessel. the clear aqueous top phase was decanted and the black colored precipitate repeatedly washed by distilled water and centrifuged to remove excess nh4oh till the ph of the supernatant became neutral (ph~7.0). the centrifuged nps were washed with c2h5oh and dried at 150 ᴼc for 2 hours to obtain the iron oxide nps-sio2. 2.3. characterization 2.3.1. x-ray diffraction analysis (xrd) phase analysis of the iron oxide nps and iron oxide nps-sio2 adsorbents was carried out by x-ray diffractometer (model 7000s, schimadzu corporation, japan), equipped with a cu-kα radiation (λ=1.5406 å) source using a nickel filter and continuous scan mode in the range 10º < 2θ < 80º. the crystalline sizes of the iron oxide nps and iron oxide nps-sio2 adsorbents were determined using the debye-scherer’s equation (1). d = (0.94𝜆) 𝛽𝑐𝑜𝑠𝛳 (1) where d is the average crystalline diameter, 0.94 is the scherer’s constant, λ is the x-ray wavelength, β is the line broadening at half the maximum intensity and θ is the bragg’s angle in degrees. the lattice parameter ‘a’ and interplanar spacing dhkl was determined by bragg's equations (2) and (3) dhkl = 𝜆 2𝑠𝑖𝑛𝜃 (2) dhkl = 𝑎 √ℎ2+𝑘2+𝑙2 (3) 2.3.2. fourier transform infrared spectroscopy (ftir) ftir spectra of the iron oxide nps and iron oxide nps-sio2 samples were recorded on a spectrophotometer equipped with a deuterium triglycine sulfate (dtgs) detector (model spectrum 65 ft-ir spectrometer, perkin elmer usa). each sample of 1-2 mg was thoroughly mixed with approximately 100 mg kbr powder and pressed into disks by a 10-ton hydraulic press at room temperature. the prepared disks were scanned in the range 4000 cm−1 to 500 cm−1 at a resolution of 4 cm−1. 2.3.3. adsorption experiments 2.3.3.1. preparation of k2cr2o7 stock solution and standard working solutions a standard stock solution of k2cr2o7 was prepared by dissolving 2.828 g k2cr2o7 in 1000 ml of distilled water. standard working solutions of different jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 83 concentrations, 20, 40, 60 and 80 mg l-1 of k2cr2o7 were prepared from this stock solution by appropriate dilutions. the ph of the solutions was adjusted to the desired value by addition of 0.1m hcl or 0.1m naoh as required. 2.3.3.2. calibration graph for determination of residual concentration of cr (vi) ions a linear calibration graph (figure 1) was obtained over the range 10, 20, 40, 60 and 80 mg l-1 of cr (vi) ions on a uv-vis spectrophotometer (model t 80+, pg instruments ltd., uk) with 1cm quartz cells at a wavelength of 540 nm. a commonly used specific reagent for the spectrophotometric determination of cr (vi) ions, 1, 5-dpc (0.5%) solution was added to the standard working solutions to generate a reddish-purple color. the 1, 5-dpc (0.5%) solution was prepared by dissolving 0.25 g 1-1, 5-dpc in 50 ml acetone. 6n h2so4 solution was prepared by adding 8.33 ml h2so4 (98%) into 50 ml distilled water to be used for ph adjustments at uv measurements. each measurement was carried out after 5 minutes of addition of the 1, 5dpc solution and completed within 20 minutes to avoid loss of color due to instability. figure 1: calibration curve for cr (vi) 2.3.3.3. adsorption experiments the parameters, initial cr (vi) concentration (10, 20, 40, 60 and 80 mg l-1), ph (2, 3, 4, 5, 6, 7, 8, 9 and 10), contact time (30, 45, 60, 90, 120 and 150 minutes) and adsorbent dosage (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8 g l-1) were chosen as independent variables and the removal efficiency of cr (vi) ions as output response. two sets of batch adsorption experiments; one set using iron oxide nps and the other using iron oxide nps-sio2 as adsorbents were performed in 100 ml conical flasks containing 50 ml cr (vi) ions working solutions and 0.1 g of the adsorbents. both sets of mixtures were stirred on an orbital shaker at 100 rpm. after the predetermined times of contact, the adsorbents were removed from the sets of mixtures by a magnetic field and filtered. the adsorbent free solutions were then analyzed for residual cr (vi) ions concentration by uv spectroscopy. determination of cr (vi) ions was performed by taking 40 ml of the solutions of the two sets in beakers and adding 3 ml of 6n h2so4 to decrease the ph below 2. once the ph was adjusted, 0.8 ml of 0.5% dpc solution was added to the solutions. after waiting for 5 minutes for stable color development, the uv measurements were performed. percentage removal of cr (vi) ions and amount of adsorption at equilibrium, qe (mg g -1), were calculated by using equations 4 and 5. removal efficiency = 𝐶𝑜−𝐶𝑒 𝐶𝑜 𝑥 100 (4) qe = 𝐶𝑜−𝐶𝑒 𝑚 𝑥 𝑉 (5) where co and ce are the initial and final concentration of cr (vi) ions (mg l-1) in the solutions, respectively, v is the volume (l) of the tested solutions and m is the mass of the adsorbents (g) used. 2.3.4. adsorption isotherms the adsorption isotherms were analyzed using the langmuir and freundlich isotherm models. 3. results and discussion 3.1. mechanism of iron oxide and sio2 supported iron oxide nps formations the reaction of fe2+ and fe3+ ions under alkaline conditions has been the subject of extensive investigation (bandhu et al., 2009; valenzuela et al., 2009; gnanaprakash et al., 2007; vereda et al., 2007). the proposed mechanism, a dynamic equilibrium equation, put forth for the synthesis of fe3o4 nanoparticles by the co-precipitation method (mascolo et al., 2013) includes as the first reaction, a very fast precipitation of ferric and ferrous hydroxides: fe3+ + 3oh − fe(oh)3 (s) the second reaction, a slower one, involves decomposition of the ferric oxide to feooh: fe(oh)3 (s) feooh (s) + h2o jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 84 fe2+ + 2oh− fe(oh)2 (s) the third reaction, a solid state reaction, occurs between feooh and fe(oh)2 due to the low water activity of the solution to produce fe3o4: 2feooh (s) + fe(oh)2 (s) fe3o4 (s) + 2h2o the concentration and size of the fe3o4 nanoparticles are influenced by the fe3+, fe2+ and ohions, as well as the water activity of the solution, with the overall reaction being: 2fe3+ + fe2+ + 8oh− 2fe(oh)3fe(oh)2 (s) → fe3o4 (s) + 4h2o the stoichiometry of fe+2 to fe3+ molar ratio, 1:2 used in this study is considered the stoichiometry for synthesis of high purity fe3o4 nps magnetite (mascolo et al., 2013). the final [oh−] concentration, related to the ph and base amount, controls the nucleation and growth of the fe3o4 nps influencing the particle size and saturation. 3.2 x-ray diffraction figure 2 (a and b) show the xrd patterns of the iron oxide nps and iron oxide nps-sio2 adsorbents. the diffraction patterns have well defined diffraction peaks, indicating that the samples were crystalline. the apparent absence of lines 110 (d = 4.183å) at 2θ = 21.22° and 104 (d = 2.700å) at 2θ = 33.15° indicated that both goethite (α-feooh) and hematite (α-fe2o3) were not formed. peaks of fe(oh)3 (d = 3.376å) at 2θ = 26.38° as well as other phases of iron oxide hydroxides, γ-feo(oh) and δ-feo(oh) were also not detected. the other two forms of iron oxide, magnetite (fe3o4), and maghemite (γ-fe2o3) have a spinel structure. their lines being very close, makes it is very difficult to distinguish them from one another by x-ray diffraction. the color of the just synthesized iron oxide nps was black in color indicating that the major form of iron oxide should be fe3o4. the γ-fe2o3 phase is known to exhibit a few extra peaks at 23.77° (210) and 26.10° (211), though with weak intensities (kim et al., 2012). based on the color and two extra typical peaks alone, it cannot be definitely ascertained whether the iron oxide nps formed were pure fe3o4 nps as trace amounts of γfe2o3nps may probably be formed as contaminant during the co-precipitation processes. γ-fe2o3 nps are orange red to brown in color and very different from black color fe3o4, but when present in trace amounts in a fe3o4 nps sample it is not possible to distinguish it by color. a comparison of the xrd patterns of the prepared iron oxide nps and iron oxide nps-sio2 adsorbents (figure 2a and b) after washing and drying with the patterns of pure commercial fe3o4 nps (sigma–aldrich 310069) and γ-fe2o3 nps (sigma–aldrich 544884) (figure 3a and b) (kim et al., 2012) shows that the synthesized adsorbents display the characteristic (210) and (211) peaks indicating the presence of the γ-fe2o3 phase. the transition of the fe3o4 nps phase to the γfe2o3 phase in the adsorbents is attributed to the oxidation process initiated during the iron oxide nps synthesis, drying at elevated temperature of 150°c and subsequent storage in air prior to characterization and further use for the cr (vi) ions adsorption experiments. there was a marked change in color observed from the initial black color of the just synthesized iron oxide nps prior to drying to red brown after drying and storage. it has been shown that fine size fe3o4 crystals (e.g., 10-20 nm) rapidly undergo transition to γ-fe2o3 at around 150°c, whereas the larger fe3o4 particles were more thermally stable and did not start the transition to γfe2o3 until about 315°c (lauer jr. et al., 2001).the obtained xrd patterns and visual color observations made are in agreement. the series of characteristic diffraction peaks observed in the xrd patterns of the adsorbents (figure 2(a and b)) at 2θ of 30.2°, 35.5°, 43.2°, 53.6°, 57.3° and 63° are indexed as (220), (311), (400), (422), (440), and (511) crystal planes correspond to a cubic unit cell of fe3o4, and match the inverse-spine structure. the peaks correspond to maghemite phase (210) and (211) also observed in fe3o4-sio2 phase due to the transition of fe3o4 nps to γ-fe2o3. the diffraction peaks of the iron oxide nps-sio2 adsorbent (figure 2b) were marginally broader than those of the iron oxide nps adsorbent, which indicated the presence of a still finer nature and smaller crystallite size of the nps in the former. in addition, the pattern showed the peaks for sio2. the sio2 was of the crystalline form since the broad peak at the 2θ value of 22°, a characteristic of sio2 in the amorphous form was absent. the sharp xrd peaks at 2θ values of 20.81, 26.49 and 50.1 (overlapped by the contribution from the iron oxide nps) indicated that sio2 was in the crystalline form (saceda et al., 2011). jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 85 figure 2: x-ray diffraction patterns of (a) iron oxide nps and (b) iron oxide nps-sio2. figure 3. x-ray diffraction patterns of commercial powders (a) magnetite (fe3o4), sigma–aldrich 310069 (b) maghemite (γ-fe2o3), sigma– aldrich 544884.the characteristic (210) and (211) peaks of the maghemite phase are obvious. the calculated crystal size of the iron oxide nps and iron oxide nps-sio2 adsorbents were 13.5 nm and 12.8 nm respectively and in close approximation. these particle sizes confirm the capping of fe3o4 with sio2 from growth and agglomeration. the fe3o4 phase transition to γ-fe2o3 nps is due to oxidation of fe (ii) to fe (iii). this transition takes place at relatively low temperatures, even at room temperature, in ultrafine fe3o4 nps due to the exposed large surface area of fe3o4. once oxidation is initiated it tends to go to completion within the particles (haneda and morrish, 1977). the lattice parameters of fe3o4 and γ-fe2o3 phases are very close and difficult to be differentiated unless it is a single phase of well-crystallized structure. the calculated lattice parameters (table 1) for the iron oxide nps and iron oxide nps-sio2 adsorbents were 8.3504°a and 8.373°a respectively and lie in between those of commercial fe3o4 (8.396 ˚a [jcpds 19-629]) and γfe2o3 (8.3515å [jcpds 39-1346] (kim et al., 2012). these values affirm silica supported iron oxide nps adsorbents that prepared were a mixture of fe3o4 and γfe2o3 phases. the interplanar spacing for the iron oxide nps and iron oxide nps-sio2 adsorbents are lower than the values reported for bulk magnetite (jcpds card no. (79-0417)) [d311= 2.531]) (ghandooret al., 2012) and are attributed to the formation of γfe2o3 (a = 8.347 and d311=2.517) (victoria et al., 2007; cornell and schwertmann 2003). table1: interplanar spacing, lattice parameters of iron oxide nps and iron oxide nps –sio2 sample calculated particle size interplanar spacing dhkl (å) lattice parameter ‘a’ (å) iron oxide nps 13.5 nm 2.51774 8.3504 iron oxide npssio2 12.8 nm 2.52463 8.373 magnetite (fe3o4) sigma–aldrich no.310069 1 μm 8.396 (jcpds 19-629) maghemite (γ-fe2o3) sigma–aldrich no. 544884 <50 nm 8.3515 (jcpds39-1346) jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 86 3.3 ftir analysis figures 4 (a & b) show the ftir spectra of the iron oxide nps and iron oxide-sio2 nps respectively after drying at 150ᴼc. in both spectra, the broad band in the proximity of 3400 – 3412 cm1 and at 1634 cm-1 are attributed to the stretching vibration of the o-h groups on the surface of the nps (petcharoen and sirivat, 2012; haw et al., 2011) and or to adsorbed water on the surface. a third expected vibration, however, from condensed octahedral fe2o6 at 390cm −1) (jitianu, et al., 2006) could not be identified due to the scanning range limitation. the band at 1119 cm-1 is attributed to the feoh bond due to octahedral sites of the fe3o4. figure 4: ft-ir spectra of (a) iron oxide nps and (b) iron oxide nps-sio2. a sharp peak at 2360 cm-1 is the co2 vibration (banerjee and chen, 2007). the band observed in the region of 567 cm-1 to 588 cm-1 with a shoulder in the proximity700 cm-1 is attributed to presence of fe3o4 (sun et al., 2009). this band overlaps a characteristic band of γ-fe2o3 at 582 cm -1 and the distinct highfrequency shoulder in the proximity of 635 cm-1 to 642 cm-1 is also characteristic to γ-fe2o3 (fu et al., 2008). both these bands correspond to the ν(fe-o) deformations in the tetrahedral and the octahedral sites. further, as seen from figure 4b, the weak bands between 800 and 1260 cm–1 are ascribed as a superimposition of various sio2 peaks and si–oh bonding (vasconcelos et al., 2002). 3.4. factors affecting chromium adsorption 3.4.1 effect of initial cr (vi) ion concentration on adsorption standard working solutions with cr (vi) ions concentration of 20, 40, 60 and 80 mg l-1 and optimal ph 3 were equilibrated for 120 minutes using an absorbent dose of 0.7g l-1at room temperature. figure 5 shows that the cr (vi) ions removal efficiency of the absorbent iron oxide nps-sio2 was higher than that of the adsorbent iron oxide nps at all concentrations. the decrease in adsorption efficiencies of the iron oxide nps and iron oxide nps-sio2 with increasing standard working solution concentration ranged from 74% to 39% and 97.4% to 55% respectively. at low initial concentrations, the ratio of the initial number of cr (vi) ions to the accessible active sites of the adsorbents will be low with the reverse occurring at higher initial concentration. thus, the removal efficiency of cr (vi) is higher at lower cr concentration and lower at higher concentrations with further residual cr (vi) ions remaining in the aqueous solutions (radnia et al., 2012). figure 5. effect of initial concentration of cr (vi) on removal efficiency of iron oxide nps and iron oxide nps-sio2 (c0 = 10–100 mg l -1, ph = 3, adsorbent dose = 0.7 g l-1, contact time = 120 minutes and room temperature). the higher removal efficiency by the iron oxide npssio2 adsorbent in comparison to the iron oxide nps is attributed to the presence of sio2 gel. in the adsorption process, factors which influence the capacity of the silica for the removal of cr (vi) from aqueous solutions include the structural texture and characteristics of the gel particles such as surface area, porosity, and the availability of surface silanols. for example, it is reported that sio2 gels because of having high surface area, high mass exchange characteristics, and jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 87 availability of high siliceous surfaces, are the mostly utilized substrates to be modified for the removal of toxic metal ions (jal et al., 2004). at the same time, it has been shown that the surface of sio2 strongly binds fe (iii) and cr (iii) via surface complexation (fendorf et al., 1994; flogeac et al., 2005; oh et al., 2007). thus, it is reasonable to presume that the silica gel present in fe3o4-sio2 provides sites for adsorption of fe (iii), cr (iii), and other reaction precipitates such as fe (iii)hydroxides and cr (iii)/fe (iii) hydroxides. this would lead to more free binding sites for cr (vi) on the iron oxide nps. another contributing factor is the smaller size of the iron oxide nps in the iron oxide nps-sio2 adsorbents as deduced by xrd analysis resulting in large surface area and binding sites available for adsorption. based on the enhanced performance of the adsorbent iron oxide nps-sio2 adsorbent compared that of the adsorbent iron oxide nps for the removal of cr (vi), other factors such as ph, adsorbent dose and contact time that affect the adsorption behavior were evaluated only for the iron oxide nps-sio2 adsorbent. 3.4.2. effect of ph on the adsorption of cr (vi) ions the aqueous ph significantly modifies heavy metals adsorption, influencing surface chemistry (chowdhury et al., 2012), determining the adsorbent surface charge and the degree of ionization and speciation of the adsorbed species (al-qodah, 2006; ahmed et al., 2013; badr and al-qahtani, 2013). in general, the surfaces of metal oxides are covered with hydroxyl (oh) groups that vary in form at different ph levels. these groups, either from the adsorption of water or from structural attributes, are the functional groups of iron oxides. the groups have a double pair of electrons together with a dissociable hydrogen atom which can help them to react with both acids and bases. charge on iron oxide surfaces is generated by the dissociation (ionization) of these oh groups. this results in the adsorption or desorption of protons depending on the ph of the solution. the effect of ph on the adsorption of cr from the standard working solutions containing 20, 40 and 60 mg l-1 cr (vi) was evaluated only for the iron oxide npssio2 adsorbent at a dose of 0.7 g l -1 and 120 minutes contact time (figure 6). maximum cr removal efficiency obtained was 96.5, 88 and 80% respectively at ph 3 from the above standard working solutions. the efficiency increased sharply between ph 2-3 from 57.7% to 96.5%, then decreased rapidly to 50.5% with an increase in ph from 3 to 7 and then tapered sharply to 45% with a further increase in ph between 7 and 9. since the iron oxide nps-sio2 adsorbent is a mixed form of maghemite–magnetite, the acidity constants of a specific surface group will depend on the abundance of fe2+or fe3+ and its hydrolysis products. the dominant functional groups of most iron oxide surfaces are expected to be fe2+ or feoh+ when the solution ph is acidic; and fe(oh)2 0 and fe(oh)3 − when the solution ph is basic. the high cr (vi)ions adsorption observed in the lower ph acidic range is due to the iron oxide nps surface having a net positive charge form fe-oh2 + surface groups. at low ph, the different cr anionic species (cr2o7 2−, hcro4 −, cr3o10 2−, cr4o13 2−) coexist in water (yuan et al., 2009). at ph 2–3, hcro4 is favorably adsorbed due to its low adsorption free energy (−2.5 to−0.6 kcal/mol) (chowdhury et al., 2012). figure 6: effect of initial ph on removal efficiency by iron oxide nps-sio2 (c0 = 20, 40 and 60 mg l 1, adsorbent dose = 0.7 g l-1 and contact time = 120 minutes). at higher ph, the surface oh groups on the iron oxide np surface are fe(oh)2 0 and fe(oh)3 −. because of this negative surface charge of iron oxide, the surface will repel the negatively charged cr (vi) ion species at higher ph values. fe(iii) in solution (from maghemite) will form hydrated ferric oxides (hfo) nps. adsorption keeps the cr (vi) ions on the iron oxide surfaces through lewis acid base interactions wherein the surface fe atoms are lewis acids that react with lewis bases (e.g., jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 88 water). the surface oh groups of the iron oxides are the chemically reactive entities at the surface of the solid in an aqueous environment possessing a double pair of electrons that enables them to react with acid and bases (chowdhury et al., 2012). 3.4.3. effect of adsorbent dose on cr (vi) ions removal the effect of the dose of iron oxide nps-sio2 adsorbent in the range of 0.1 g l-1 to 0.8 g l-1 on the removal of cr (vi) ions from the standard working solutions of cr (vi) concentration 20 and 40 mg l-1, at ph 3 for 120 minutes contact time is shown in figure 7. from the figure it is observed that the percentage removal of cr (vi) ions increased from 58 to 96.4% and from 52% to 85% for the working standard solutions of cr (vi) concentration 20 and 40 mg l-1 respectively with increasing amount of adsorbent dose till 0.7gl-1 beyond which it saturated. this is explained by the increase of effective surface area on which metal ions will be adsorbed with absorbent dose, meaning that increasing the adsorbent dose will result in an increase in the number of active sites available for adsorption (sharma et al., 2009).on the other hand, this will result in a continual decrease of the adsorption capacity with increase of adsorbent dose and this situation is a result of remaining of effective surface area without saturation along with the adsorption process. similar results have been observed in the other seminal studies using different adsorbents for the removal of cr (vi) (li et al., 2008). figure 7: effect of adsorbent dose on removal efficiency by iron oxide nps-sio2 (c0 = 20 and 40 mg l 1, ph = 3, contact time = 120 minutes, and room temperature). at an adsorbent dose of 0.8 g l-1, the percentage removal is 95 and 84.5% for the standard working cr (vi) solutions of concentration 20 and 40 mg l-1 respectively which is marginally lower by ~1.5 and 0.5% compared to the percentage removal at an adsorbent dose of 0.7 g l-1.thus, under the given experimental conditions, a 0.7 g l-1 adsorbent dose is deemed optimal for maximum percentage cr (vi) ions removal. 3.4.4. effect of contact time on the adsorption of cr (vi) the rates of cr (vi) ions removal from three standard solutions with initial cr concentration of 20, 40 and 60 mg l-1 at ph 3 using a fixed iron oxide nps-sio2 adsorbent dose of 0.7 g l-1 and contact time ranging from 25 to 150 minutes at room temperature are shown in figure 8. from the figure, it is observed that adsorption equilibrium was achieved in 120 minutes beyond which it remained constant to 150 minutes. the rapid metal uptake by the adsorbent in majority is attributed to adsorption on the external surfaces of the iron oxide nanoparticles where almost all of the sorption sites exist as well on the sio2 gel particles. any contribution by micro-porous adsorption is essentially expected from the sio2 gel particles. figure 8: effect of contact time on removal efficiency (c0 =20, 40 and 60 mg l -1, t = 25°c, adsorbent iron oxide nps-sio2 dose = 0.7 g l -1, ph = 3, and room temperature). thus, it is easy for the cr (vi) ions to access these active sites, resulting in a rapid approach to equilibrium. a two-step fundamental mechanism of cr (vi) ions adsorption onto the iron oxide nps-sio2 can be jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 89 expected. in a first step, cr (vi) ions will migrate from the bulk solution phase to the outer particle surfaces of the adsorbent and establish contact (film diffusion). in the second, electrostatic attraction or reactions occurring between adsorbate cr (vi) ions and adsorbent will take place (singh et al., 1993). 3.5 adsorption isotherms in this work because of the better performance of the adsorbent iron oxide nps-sio2, the adsorption isotherms of this adsorbent were analyzed only. the equilibrium adsorption isotherm model is the number of mg adsorbed per g of an adsorbent (qe) vs. the equilibrium concentration of adsorbate and provides a fundamental description of the interaction between an adsorbate and an adsorbent. the analysis data allows for predicting the adsorption capacity of the adsorbent, a main parameter required for the design of an adsorption system. equilibrium isotherm studies were carried out with different initial concentrations of cr(mg l−1) at room temperature and ph 3.the equilibrium adsorption data were analyzed by langmuir’s model (langmuir, 1918) and freundlich’s model (freundlich and heller, 1939). langmuir’s model, based on the physical hypothesis that: the maximum adsorption capacity consists of a monolayer adsorption, that there are no interactions between adsorbed molecules, and that the adsorption energy is distributed homogeneously over the entire coverage surface, essentially provides the simplest description of the adsorption process without taking into account the variation in adsorption energy (chatterjee et al., 2009; afkhami et al., 2009). the isotherm is represented by ce qe = klce qm + 1 qm (6) where ce (mg/l) is the concentration of adsorbate left in solution at equilibrium, kl is the langmuir bonding energy, qm(mg g -1) is the adsorption maximum (mg g-1) and qe(mg g -1) is the amount of adsorbate adsorbed per unit mass of adsorbent. the langmuir constants qm and kl were determined from the intercept and slope of the linear plot of ce/qe, against the equilibrium concentration ce (mg l -1) (figure 9). the freundlich isotherm model, an empirical equation, describes the surface heterogeneity of the sorbent while considering multilayer adsorption with a heterogeneous energetic distribution of active sites, accompanied by interactions between adsorbed molecules (chatterjee et al., 2009). the linearized form of the freundlich adsorption isotherm equation is lnqe= lnkf + 1 𝑛 (lnce) (7) where qe is the amount of adsorbate absorbed at equilibrium (mg g-1), ce is the equilibrium concentration of adsorbate in solution (mg l-1), and the freundlich constants (temperature dependent and the given adsorbent–adsorbate couple) kf (mg 1−1/nl1/n g−1) is the capacity of the adsorbent (mgg-1) and1/n (lm g-1) is related to the adsorption energy distribution. when the value of n is 1, the adsorption is a linear isotherm. if the value of n is less than 1 or greater than 1, it implies that the adsorption reaction is related to a chemical or favorable physical process, respectively. from table 2, the value of n is greater than 1, indicating favorable adsorption and confirming that adsorption is a physical process. the values of kf and 1/n calculated from the intercept and slope of the plot of ln qe vs. ln ce (figure 10) are shown in table 1 wherein it is observed that the values of the correlation coefficient, r2, for the fit of the experimental isotherm data to langmuir equation is more close to 1 than that for the freundlich equation. therefore, the langmuir model represents the experimental data better on the basis of values of regression coefficients. the agreement of the experimental results with the langmuir model suggests monolayer coverage of cr (vi) ions mainly on the outer surface of the adsorbent (gholipour et al., 2011). figure 9: linearization of the langmuir isotherm (ph = 3, iron oxide nps-sio2 = 0.7 g, room temperature). jibril edris et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 90 figure 10: linearized freundlich isotherm (ph = 3, iron oxide nps-sio2= 0.7 g, room temperature). table 2: parameters of langmuir and freundlich isotherm equations, regression coefficients (r) for the adsorption of cr (vi) ions on the iron oxide npssio2 absorbent at room temperature and ph = 3. 4. conclusion the synthesized adsorbents, iron oxide nps and iron oxide nps-sio2, are mixed oxides of fe3o4-γ-fe2o3 of ultrafine particle size as evidenced by color change, xrd and ftir analysis. at room temperature, the performance of the adsorbent iron oxide nps-sio2 for the removal of cr (vi) from aqueous solutions was superior to that of the adsorbent iron oxide nps vis-à-vis the initial concentration of cr (vi)with maximum adsorption capacity at ph 3. this evidenced that the incorporation of a small amount of sio2 gel in the iron oxide nps was synergistic. the removal of cr (vi) from aqueous solutions by the adsorbent iron oxide nps-sio2 at room temperature showed a strong dependency on the ph of the solution, adsorbent dosage, initial cr (vi) concentration and contact time. an increase in the adsorbent iron oxide nps-sio2 dose and decrease in the initial concentration of cr (vi) resulted in an increase in cr (vi) adsorption, while an increase in contact time lead to an increase in the removal of cr (vi). the analysis of adsorption isotherms for the adsorbent iron oxide nps-sio2 by the langmuir and freundlich adsorption isotherms showed that the langmuir isotherm had a better 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(2009). montmorillonite -supported magnetite nanoparticles for the removal of hexavalent chromium cr (vi) from aqueous solutions. journal of hazardous materials, 166 (23): 821-829. 19 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9(1), 2022 journal home page: www.ejssd.astu.edu.et astu research paper modelling and simulation of hydraulic system to measure soil compaction for agricultural field yared seifu1,, someshakher s. hiremath2, simie tola1, amana wako1 1department of mechanical system and vehicle engineering, adama science and technology university, p.o. box: 1888, adama, ethiopia 2department of mechanical engineering (precision and instrumentation laboratory engineering). (iitm) indian institute of technology, madras university chennai, india article info abstract article history: received 28 august 2021 received in revised form 11 november 2021 accepted 12 march 2022 soil compaction is one of the negative factors associated in the top layer of the soil by heavy agricultural machinery in the agricultural field that limits ploughing tool movement, plant growth and crop yield. soil compaction has been conventionally measured by using a manual operated cone penetrometer which has certain ergonomically restriction tackled by the operator, it takes more time and difficult to obtain compaction data. the study aimed to design and develop a hydraulic system to measure soil compaction for agricultural field, to simulate soil compaction measuring system using matlab simulink 2018 and to analyze the simulation output. the modelling and simulation include the hydraulic system used for actuate the compaction measuring cone penetrometer by considering the vertical force coming from double acting hydraulic cylinder as variable mass and the soil as a stiffness and damping property. from the simulation output, the hydraulic performance based on soil compaction measurement with the parameters such as hydraulic pressure as cone index, depth of operation, hydraulic torque, and power were analyzed. the time required for the cylinder extension to insert the cone penetrometer to the soil was 3.3 seconds with the maximum speed of cylinder extension of 0.3 mm/s. the maximum downward penetration resistance was 0.3 n. the pressure varies from 24 pa to 38 pa during extension of the cylinder and 0 to 15 pa during retraction with the maximum flow rate of 3.8 × 10-6 m3/s. the relationship between hydraulic power and flow rate is directly proportional. hydraulic torque and flow rate have inversely proportional relationship. keywords: agricultural field hydraulic system matlab modelling simulation soil compaction 1. introduction farm mechanization is the main indicator of the modernizing the agricultural and use of farm machines that can replace human and animal power in agricultural processes. farm machineries are used for land preparation to the harvesting steps by driving in farm land in mechanization system. during field operation, the weight of farm machinery compact the agricultural soil resulting in increase and decrease of soil bulk density and porosity, respectively due to the contact corresponding author, e-mail: yaredseifu80@gmail.com https://doi.org/10.20372/ejssdastu:v9.i1.2022.391 with the tires or tracks of tractors (ungureanu et al., 2015). soil compaction is not only caused by farm machinery, but also by livestock trampling (chyba et al., 2014). the risk of compaction is also dependent on the soil tillage and crop rotations, soil moisture and working depth. soil compaction has been continuously disregarded in the management of agricultural traffic, even though it is extremely relevant to maintain the soil http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i1.2022..... yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 20 quality of different agro ecosystems (guimaraes et al., 2019). soil compaction is the major problem that affect the crop production by limiting the potential yield (scarparea et al., 2019). top layer of agricultural soil compaction by heavy agricultural machinery is one of the main negative factor which limits plant growth and crop yield (benevenute et al., 2020). the compacted soil is difficult to plough since its strength and draft resistance is high. physical properties of soil play an important role in determining soil’s suitability for agricultural, environmental and engineering uses. the supporting capability; movement, retention and availability of water and nutrients to plants; ease in penetration of roots, and flow of heat and air are directly associated with physical properties of the soil (phogat et al., 2015). soil strength can be measured traditionally using a hand operated soil cone penetrometer (guimaraes et al., 2019). soil cone index is widely used to assess soil strength or soil compaction in tillage research. hence soil cone penetrometer is an important measuring instrument to determine soil physical properties. excessive compactness is detrimental to maintain a good root environment. it also reduces penetration of water and increases runoff and erosion (mudarisov et al., 2020). the forces from agricultural equipment cause soil particles to compact closer and organized into a smaller volume. as soil particles are compressed together, the space between particles (pore space) is reduced, thereby reducing the space available in the soil for air and water. kumar et al. (2019) designed and developed hydraulically operated mechanical soil cone penetrometer to measure soil resistance on tillage in the field up to a maximum cone index value of 2000 kpa. tekin et al. (2007) developed a hydraulic-driven soil penetrometer for measuring soil compaction in field conditions. wang et al. (2020) designed on the basis of hydraulic principle, which uses tractor hydraulic system and comprised of driving unit for inserting the probe into the soil at the desired speed. in mechanized farming system, farm machineries are used from land preparation to harvesting by operating in farm land. throughout the literature survey conducted, in ethiopian there is no research done so far on hydraulically operated tractor mounted soil compaction measuring system. in field experiment level, ethiopian soil compaction rate and plant/seed growing relation should be studied for improving the farming system. a hydraulically operated soil compaction measuring system which is mounted on tractor in tillage field has not been studied so far. in global level, many researches were conducted on related areas. in the development of separate system for measuring soil resistance and soil compaction, almost all researchers were used cone penetrometer. soil compaction measuring instrument in field work at different soil depth and soil profile is crucial in our country to overcome the aforementioned problems. therefore, the study aimed to design and develop a hydraulic system to measure soil compaction for agricultural field, to simulate soil compaction measuring system using matlab simulink and to analyze the simulation output. from the simulation output, the hydraulically actuated soil compaction measurement which consists of parameters such as hydraulic pressure as cone index, depth of operation, soil type, hydraulic torque, and power were analyzed. 2. methodology the methodology followed in this work is summurized in figure 1. the work started by assuming standard parameters like maximum cone index value based on agrotechnical requirement. based on the assumption, the designing of hydraulic components for actuating the soil compaction instrument were done. then, according to the design, simulation on matlab simulink was done. the final step was discussion of the results based on time require for the extension and retraction of the double acting cylinder for accomplishment of the soil compaction measurement with respect to parameters like pressure difference, flow rate, hydraulic torque, power, etc. this soil testing instrument can be used in all types of soil except stony farm land since the hydraulic power damage the cone penetrometer probe. the simulation input and output parameters are shown in figure 2. the results and discussion are based on time required for the extension and retraction of the double acting cylinder. yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 21 figure 1: methodology flowchart figure 2: theoretical frame work of input output parameter 2.1. operational definition the system gates hydraulic power from the tractor hydraulic power unit which contains reservoir and pump. the hydraulic fluid passing from pump can be connected to the pressure relief valve for regulating excess pressure. the double acting cylinder movement is controlled by a four port three position directional control valves (4/3dcv). the solid line indicates the path of the fluid as shown in figure 3 to figure 5. initially, in ideal work position, the pump pressure line is connected to the off or to the middle position of 4/3dcv. as shown in figure 3, the pump pressure doesn’t pass to the double acting cylinder so that the fluid return to the tank through the pressure relief valve. figure 3: shutoff position of the hydraulic circuit of the system problem identification doing simulation using matlab simulink extracting data like hydraulic pressure, power, torque etc. results discussion and conclusions design the methodology of the work designed the components of hydraulic system start stop soil and cone penetrometer interaction operational depth hydraulic torque hydraulic power pressure (cone index) hydraulic pressure time p t a b p t farm land tank tank tank pressure relief valve double acting cylinder pump cone penetrometer 4/3 dcv yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 22 figure 4: working position of the hydraulic circuit of the system figure 5: retract position of the hydraulic circuit of the system when the 4/3 dcv allow the fluid coming from the tank through pump it extends the cylinder road as shown in figure 4 and inserts the cone penetrometer into the soil to measure the soil compaction. the system in figure 5 shows when the 4/3 dcv allow the fluid coming from the tank through pump and passing at the third position, it retracts the cylinder road and take out the cone penetrometer from the soil. 2.2. design and modelling the designed model of cone penetrometer was done based on force coming from the hydraulic double acting cylinder. the forces model and design acting on the cone penetrometer at static condition are downward hydraulic force and upward soil resistance (figure 6) are incorporated in design process (freitag et al., 1970). design of cylinder: design of hydraulic cylinder is based on the maximum thrust required to insert the penetrometer probe into the soil. the maximum thrust figure 6: factors affecting tillage operation required for the penetrometer can be calculated using equation 1 (perumpral, 1987). f ci a  (1) where, f = required thrust, ci = maximum cone index to be measured, and a= base area of cone in case of cone penetrometer. the maximum cone index of soil for which the system to be designed is assumed to be 3 mpa. american society of agricultural and biological engineers (asabe, 1968) adopted the standardization p t a b p t farm land pressure line tank tank tank pressure relief valve double acting cylinder pump cone penetrometer 4/3 dcv pressure gauge p t a b p t tank tank tank pump pressure relief valve 4/3 dcv pressure line s-type strain gauge load cell double acting cylinder cone penetrometer farm land pressure gauge hydraulic force upward soil resistance soil physical properties yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 23 cone penetrometer as a recommendation for field use and this is still in use today. these are cone of 323 mm2 base area and 20.27 mm base diameter with a 15.88 mm diameter probe for loose soil and the second one is a cone of 130 mm2 base area and 12.83 mm base diameter with a 9.53 mm diameter probe for firm soil. using the first standard, the maximum force required for the penetrometer can be calculated as: maximum force (f) = 3×106×3.23×10-4 = 967 n. the piston rod diameter is checked for buckling by using euler’s formula (equation 2). so, euler’s strut theory is used to withstand buckling (de cicco et al., 2022) . 2 2 ( ) 2 64 4 im n f k l e d    (2) where, f (buckling load on cylinder rod) = maximum force applied on cylinder rod × 2, e = young’s modulus of elasticity (200 gpa for steel en8), d = diameter of cylinder rod, l = length of cylinder rod (taking 200 mm) and k = constant, 2 for one end fixed and another end free. 2 2 ( ) 2 9 967 2 64 4 0.008418 8 0 0.2 .42 200 1i m n d mm m         the aavailable size of cylinder rod is 32 mm with cylinder bore of 100 mm. hence, the cylinder rod is safe for buckling. as a result, equation 3 can be used to find the smallest diameter of cylinder rod that can withstand the load (de cicco et al., 2022). 4 f d   (3) where, σ is maximum yield stress of cylinder road material (380 mpa) and taking factor of safety = 2 4 967 2 6.48 380 d mm       available size of cylinder rod is 32 mm. hence, the cylinder can resist the load. the pressure required to developed thrust on the annular side of the cylinder can be calculated using equation 4 (watton, 2007). 2 2 ( ) 4 c r f f p a d d     (4) where, p is pressure coming from hydraulic system, dc and dr are cylinder diameter and cylinder road diameter, respectively. 2 2 967 1.3724 (100 32 ) 4 p bar d     relief valve pressure should be adjusted at a pressure >25% than that required to give a thrust, considering the pressure drop in the pipes and other components. the bore side and annual side in m2 of the cylinder are calculated using equation 5 and 6, respectively (watton, 2007). full bore area, 2( ) 4 c a d   (5) 2 2 2 (100 ) 7854 78.54 4 a mm cm     annulus area, 2 2( ) ( ) 4 c r a a a d d      (6) 2 2 2 2 (100 32 ) 7050 70.50 4 a mm cm      the piston velocity should be 3 cm/s to penetrate into soil to meet the standard cone penetration velocity as per asae s313.3. when piston rod is extending piston velocity, v can be calculated using equation 7 (mirzaliev et al., 2020): 3 / 30 /e e q q v cm s mm s a a a      (7) where, qe = flow into full bore end of cylinder when extending in m3/s, qe = flow from annulus end of cylinder when extending e q a v  (8) 3 3 78.54 3 235.62 / 0.01414 / 14. 14qe cm s m min lpm     eq a a v   (9) 3 3 70.5 3 211.5 / 0.1269 / 12.69 e q cm s m min lpm     figure 7: (a) cylinder under extended condition (b) cylinder under retracted condition. qe qe ve qr qr vr (b) (a) yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 24 when piston rod is retracted, piston velocity, v, can be calculated using equation 10 (watton, 2009): r r q q v a a a    (10) where, qr= flow into full bore end of cylinder when retracting in m3/s, qr= flow from annulus end of cylinder when retracting in m3/s = qe =235.62 cm 3/s 235.62 3.34 / 70.5 v m s  3 3 78.54 3.34 262.324 / 0.01574 / 15.74 r q a v cm s m min lpm       3 3 78.54 3.34 262.324 / 0.01574 / 15.74 r q a v cm s m min lpm       table 1: design summary for the double acting cylinder s. no. parameters value 1 cylinder diameter 100 mm 2 rod diameter 32 mm 3 stroke length 200 mm 4 stroke speed 30 mm/s 5 return stroke speed 33.4 mm/s 6 oil flow required in forward stroke 14.14 lpm 7 oil flow required in return stroke 15.74 lpm 8 full bore area 7854 mm2 9 annual area 7050 mm2 2.3. modeling of the soil compaction measuring system the matlab simulink of hydraulic system model in figure 6 includes a tractor auxiliary hydraulic system which includes hydraulic oil, hydraulic pump for crating pressure and velocity, hydraulic motor for creating mechanical rotation. the system get power from the hydraulic reference unit passing through pump. the pressure relief valve used for regulating excess pressure and save the four by three directional pressure control valve. manual operated four port three position directional control valve directs the directional movement of the fluid as well as stops the operation. the double-acting cylinder create linear movement and inserting cone penetrometer into the soil for measuring the vertical soil pressure. a real system gates hydraulic power from the tractor hydraulic power unit, which contains a reservoir and pump. the pressure applied from the cylinder is modelled as a variable mass and the soil is modelled as solid particle which contains its own spring and damping property. the model input parameters are the design parameters which are summarized in table 1. figure 8: matlab simulink model of the hydraulic system yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 25 3. results and discussion the results of the hydraulic cylinder simulation outputs which include time required for the cylinder extension and retraction, pressure variation during cylinder extension and retraction, soil compaction resistance in a form of damper and soil stiffness in a form of spring property, the flow rate through pump to hydraulic cylinder, power and torque are presented and discussed in this section. the simulation output graph (figure 9) represents a double-acting hydraulic cylinder output parameter during the extension of cylinder. the model of the cylinder is constructed from the translational hydro-mechanical converter and translational hard stop blocks. the rod motion is limited with the mechanical translational hard stop block. the time required for the cylinder extension to insert the cone penetrometer to the soil is 3.3 seconds and the maximum speed of cylinder extension is 0.3 mm/s. the simulation output graph (figure 10) shows the pressure variation through pressure line and returning line. connections a and b are hydraulic conserving ports. port a is connected to converter a and port b is connected to converter b. figure 9: a) hydraulic cylinder speed with respect to simulation time and b) single stroke distance with respect to simulation time figure 10: a) pressure variation in hydraulic cylinder at port a with respect to simulation time and b) port b with respect to simulation time figure 11: soil compaction resistance force with respect to simulation time a) b) a) b) yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 26 the block directionality is adjustable and can be controlled with the cylinder orientation parameter. the result shows in the first 3 seconds the pressure in port a varies within 24 pa to 38 pa and pressure in port b varies within 0 to 15 pa. the graph in figure 11 shows soil compaction resistance force with respect to simulation time based the model of soil as solid variable mass. the result indicates that the maximum soil resistance force is 0.03 n. the block in model has one mechanical translational conserving port and one physical signal input representing the soil as mass. the block positive direction is from its port to the reference point. this means that the inertia force is positive if mass is accelerated in positive direction. based on this, the graph output in figure 12 shows the maximum downward penetration resistance force of 0.3 n with the maximum penetration speed of 0.032 mm/s. the flow rate of oil from the pump used to create linear motion for the cylinder road is plotted in figure 13. from the plot, the maximum flow rate is 3.8×10-6 m3/s. the property of the flow rate during the cylinder extension is increasing for the first half second and start to decrease up to 3 minutes during the cone penetrometer start to penetrate the soil. during penetration, again it reaches to maximum flow rate and finishes the extension of the road and starts retracting the cylinder road. the hydraulic power graph during the soil compaction measurement model shown in figure 14 indicates the maximum hydraulic power required to extend and retraction the hydraulic cylinder to inserts and take out the cone penetrometer is 1.9 kw. the relationship between hydraulic power and flow rate is directly proportion as shown in figure 13 and 14. figure 12: a) translational spring force with respect to simulation time and b) speed require for insert the cone penetrometer in to soil with respect to simulation time figure 13: pump flow rate with respect to time b) a) yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 27 figure 14: pump hydraulic power with respect to simulation time the hydraulic torque graph during the soil compaction measurement model is shown in figure 15. it indicates the maximum torque required to extend and retract the hydraulic cylinder and to inserts and take out the cone penetrometer is 0.0502045 nm. the minimum torque required to extend and retract the hydraulic cylinder, and to inserts and take out the cone penetrometer is 0.05020362 nm. the relationship between hydraulic torque and flow rate is inversely proportional as shown in figure 13 and 15. a model of pump with constant volumetric displacement that supplies mechanical energy to a hydraulic system are susceptible for losses due to flow leakage and friction torque. the pump may operate in both the forward and reverse directions depending on the rotation of the shaft. the simulation output graph is shown in figure 16. the result shows the pressure decreases from 38.05 pa in a few seconds to 37.90 pa and start increasing and reaches 38 pa. when the cone figure 15: pump hydraulic torque with respect to simulation time figure 16: pump pressure difference during extension and retraction the hydraulic cylinder with respect to simulation time. yared seifua et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 28 penetrometer come into contact to the soil, the pressure decreases to minimum pressure of 37.8 pa. during the interaction of soil and cone penetrometer, the pressure variation graph shows sine wave and finishes the first cylinder extension cycle. in the cycle, the pressure variation is from 37.87 pa to 38.13 pa. 4. conclusion in this study an attempt has been made to develop a hydraulically operated soil compaction measurement system. matlab simulink 2018 is used to model and simulate parameters like vertical force as a variable mass and the soil as a stiffness and damping property. the cone index, which is the resisting pressure of soil, of 3 mpa is used for mathematical analysis. the maximum hydraulic pressure used for extend and retract the double acting cylinder for the purpose of inserting and take out the cone penetrometer is 38.05 pa. the designed system can measure up to maximum cone index on 3 mpa but for this selected soil parameters the maximum pressure required is 38.05 pa. from simulink simulation the time required for the cylinder extension to insert the cone penetrometer to the soil is 3.3 seconds with the maximum speed of cylinder extension of 0.3 mm/s. the maximum downward penetration resistance force of 0.3 n and soil compaction resistance force based the model of soil as solid variable mass the maximum soil resistance force is 0.03 n. the maximum flow rate is 3.8×10-6 m3/s. flow rate is directly proportion with hydraulic power and inversely proportional with torque. acknowledgment this research work is sponsored by dire dawa university. the authors would like to thank adama science and technology university for their support in a form of facilitating phd scholarship for the student. reference benevenute, p. a. n., morais, e. g. d., souza, a. a., vasques, i. c. f., cardoso, d. p., sales, f. r., severiano, e. c., home m, b. g. c., casagrande, d. r., & silva, b. m. (2020). penetration resistance: an effective indicator for monitoring soil compaction in pastures. ecological indicators, 117(2020)106647. https://doi.org/10.1016/j.ecolind.2020.106647 chyba, j., kroulík, m., krištof, k., misiewicz, p. a., & chaney, k. (2014). influence of soil compaction by farm machinery and livestock on water infiltration rate on grassland. agronomy research, 12(1): 59–64. de cicco, d., yaghoobi, h., & taheri, f. (2022). development of practical semi-empirically and statistically-based equations for predicting the static and dynamic buckling capacities of 3d fibre-metal laminates. thin-walled structures, 170: 108520. freitag, d. r., & schafer, r. w. (1970). similitude studies of soil-machine systems. journal of terramechanics, 7(2): 25-58. guimaraes .j, diserens, e., de maria, i. c., araujo-junior, c. f., farhate, c. v. v., & de souza, z. m. (2019). prediction of soil stresses and compaction due to agricultural machines in sugarcane cultivation systems with and without crop rotation. science of the total environment, 681: 424-434. https://doi.org/10.1016/j.scitotenv.2019.05.009 kumar, v., kumar, p., sahni, r. k., & thomas, e. (2019). design of tractor mounted hydraulically operated soil compaction measurement system. central institute of agricultural engineering, bhopal, 8. mirzaliev, s., & sharipov, k. (2020). a review of energy efficient fluid power systems: fluid power impact on ene rgy, emissions and economics. acta of turin polytechnic university in tashkent, 9(4): 113-119. mudarisov, s., gainullin, i., gabitov, i., hasanov, e., & farhutdinov, i. (2020). soil compaction management reduce soil compactionusing a chain-track tractor. journal of terramechanics, 89: 1-12. https://doi.org/10.1016/j.jterra.2020.02.002 perumpral, j. (1987). cone penetrometer applications—a review. american society of agricultural and biological engineers, 30(4): 939-0944. phogat, v. k., tomar, v. s., & dahiya, r. (2015). soil physical properties. 1st edition, indian society of soil science scarparea, f. v., lier, q. d. j. v., camargo, l. d., r.c.m. piresc, ruiz-corrêa, s. t., bezerra, a. h. f., gava, g. j. c., & dias, c. t. s. (2019). tillage effects on soil physical condition and root growth associated with sugarcane water availability. soil and tillage research, 187: 110-118. https://doi.org/10.1016/j.still.2018.12.005 tekin, y., & okursoy, r. (2007). development of a hydraulic-driven soil penetrometer for measuring soil compaction in field conditions. journal of applied sciences, 7(6): 918-921. ungureanu, n., croitoru, ş., biriş, s., voicu, g., vlăduţ, v., selvi, k. ç., boruz, s., marin, e., & matache, m. (2015). agricultural soil compaction under the action of agricultural machinery. international symposium on agricultural engineering, 43. wang, c., zhang, y., zhang, j., & zhu, j. (2020). flow pattern recognition inside a rotodynamic multiphase pump via developed entropy production diagnostic model. journal of petroleum science and engineering, 194: 107467. watton, j. (2007). modelling, monitoring and diagnostic techniques for fluid power systems. isbn: 978-1-84996-591-0, springer science & business media. watton, j. (2009). fundamentals of fluid power control. cambridge university press; 1st edition. 62 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper synthesis and characterization of silica from awash melkaasa chemical factory waste robel mehari, fana teklemariam, hailemariam aweke, hailemariam gebregwergis department of chemical engineering, adama science and technology university, p.o. box: 1888, adama, ethiopia article info abstract article history: received 17 may 2022 received in revised form 04 july 2022 accepted 13july 2022 silica is a common name for the chemical compound silicon dioxide. it can be found naturally in abundant amount as sand and is a raw material for many useful chemicals like silicone and silicates. it can be also found as a by-product from several chemical factories. awash melkassa is one of the factories that releases this silica as a waste product. in this work, this waste, that has a silica content of more than 65%, was used as a raw material for synthesis of purified silica. here the silica was prepared by two distinct routes: basic and acidic route. in basic route, the chemical factory waste have been leached with caustic soda to prepare sodium silicate followed by reducing the silicate with an organic acid to prepare purified silica then finally size reduction by ball milling. in the second method, inorganic acids such as sulfuric acid and hydrochloric acid have been used to remove the impurities from the chemical factory waste and ball milling the purified silica to obtain the micro particles. characterization of the final products was done by sem and xrd. finally the best process for silica synthesis have been decided based on which process yields the higher silica content product which is the acidic routine. keywords: acid leaching basic leaching silica kaolin micro particles chemical factory waste 1. introduction silica is another name for silicon dioxide that is the most abundant compound in the earth’s crust. this compound occurs naturally as sand making up more than half of it by mass (radhip et al., 2015). the term silica usually corresponds to geological sediment deposits rich in grains of quartz (woronko, 2016). besides occurring naturally, silica can be synthesised from different raw materials. this usually comes from either purification of sand (radhip et al., 2015; thio et al., 2020) agricultural and industrial waste (vaibhav et al., 2015; espíndola-gonzalez et al., 2010) or a class of silica called bio silica which is obtained from the purification of the ashes of biomass like rice straw (zaky et al., 2008) or husk(moosa et al., 2017), sugar cane bagasse (tadesse et al., 2019), coconut (anuar et al., e-mail: robelmarvolo@gmail.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.483 2018), corn cob (okoronkwo et al., 2016) and many more. this surge in the production of silica production is to meet the ever increasing demand for it in construction industry, cosmetic industry, chemical manufacturing industry, food industry and many more. its inherent chemical stability and versatility in usage of many different industries like electronic device manufacturing, ceramic manufacturing, cement industry, pharmaceutical industries, food industries (packaged as powders for preservation) and so forth.(fleming et al., n.d.; kasaai, 2015; bahari et al., 2011). among the different methods of preparing silica, the synthesis from agricultural (biological) or industrial waste materials is becoming attractive because it is http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.483 robel mehari et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 63 cheap, environmentally friendly and non-energy intensive (singh et al., 2020). typically, the waste from different backgrounds, which is in the form powder, is rich in silica and it will be treated with acid to remove unwanted impurities like iron oxide, aluminium oxide or calcium oxide (kasaai, 2015). then after, the purified powder will be leached with aqueous sodium hydroxide to form sodium silicate solution. this clear solution will be separated from other sediments by decantation or sedimentation and acids will be added to it to reduce it back to silica. the silica is then separated from the sodium salts solution formed from these acids and washed multiple times with distilled water and dried to obtain high purity silica (zaky et al., 2008; moosa et al., 2017). awash melkassa chemical factory previously known as awash melkassa aluminum sulfate and sulfuric acid share company (amassasc) is a public enterprise which is located 115 kms from the capital addis ababa. its main products are sulfuric acid (h2so4), aluminum sulfate (al2(so4)3) and hydrogen peroxide (h2o2). the aluminum sulfate sub plant uses kaolin (al2si2o5(oh)4) a natural clay found in hagere selam, a place in southern nations, nationalities and peoples region and sulfuric acid to produce the alum (aluminum sulfate). in this process the acid leaches aluminum oxide from the kaolin and the residue, which is not soluble in water, will be filtered out and discarded as waste. preparing silica from this residue is the main goal of this study. in this study the residue named chemical factory waste (cfw) was used thermally pre-treated and used to prepare silica by two distinct routes: basic and acidic routes. morphological characterization of the final products was done by scanning electron microscopy (sem) and the crystallinity of the product was analyzed by x-ray powder diffraction spectroscopy (xrd). the composition of the cfw and kaolin was checked using x-ray fluorescence (xrf) spectroscopy 2. materials and methodology 2.1. chemicals the raw material is chemical factory waste (cfw) from awash melkassa chemical factory. sodium hydroxide anhydrous, 99% (w/w) alfa aesar, sulphuric acid 98% (w/w) alfa aesar and glacial acetic acid, 99 %(w/w) alfa aesar, hydrochloric acid 35% (w/w) alfa aesar were used with no further purification. distilled water was used to purify and wash the samples after every step. 2.2. methodology an extraction of silica from cfw was conducted by two methods: by a means of alkalization (basic) route using naoh and by acidic route using hcl and h2so4. a) basic route the alkalization route was performed under an optimal condition with the silica to naoh ratio of 1:1.33 on dry basis (w/w). first the chemical waste was fetched from awash melkassa chemical factory and the amount of waste that we need for our project was weighed out. the cfw was treated by heat in the furnace for 4 hours at 700°c, and then it was milled by a ball milling for 10 minutes at 500 rpm. after that the silica extraction process was started. to prepare sodium silicate (na2sio3) 43.6 g the cfw was reacted with an alkaline solution by dissolving 38.8 g sodium hydroxide (naoh) in 500 ml of distilled water. this process has been carried out at 90°c for about three hours. afterwards, the solution was stirred for about 4 hours at 25°c using magnetic stirrer. after this process had been completed the residue was filtered out from silicate solution by using vacuum pump. then acetic acid was added to the sodium silicate solution to reduce the sodium silicate in to silica or silicon dioxide. in this step an excess amount of acetic acid was to the aqueous solution to reduce all of the sodium silicate. the result was formation of white residue, sodium acetate and water. the white residue is silicic acid which is the hydrated form of silica. this residue and liquid was separated using vacuum filtration process. then, the white residue was washed with water repeatedly to remove the impurities until the ph reached seven. since silica is not soluble in water it cannot be affected by water addition. but, the impurity can be removed with water. afterwards, the white residue was dried in an oven for 3 hours at 90°c finally, the synthesized silica was ground in the ball mill to produce a fine powder and characterization was carried out. the reaction process that may occur is the following: cfw + 2naohaq → na2sio3aq + h2o na2sio3 + ch3cooh → sio2 + na2ch3coo+ h2o robel mehari et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 64 b) acidic route the second method of extraction that had been used to extract silica from cfw was acidic route. in the acidic route hcl and h2so4 was being used in the extraction process. in this step, hcl and h2so4 was being added in to the cfw and the process was carried out for 2 hours at 100 0c. this process aimed to prepare silica by removing the impurities of the chemical factory waste like alumina and iron oxide with the help of acid to convert them into salts that can be washed away analysis. 3. result and discussion the awash melkassa chemical factory releases the cfw as a waste product at the end of the production of aluminium sulphate. the figure 1 shows cfw of awash melkassa chemical factory. since it is a residue of kaolin which is greyish-white powder, the cfw is also a grey powder. after the calcination, this cfw is completely white. this may be due to removal of oxide contaminants and the complete evaporation of water from it. figure 1: chemical factory waste (left) and kaolin deposit (right) the chemical composition of the kaolin is shown in table 1.the composition analysis was done using xray fluorescence (xrf) spectroscopy. although kaolin is primarily used in the cement and construction industry, it can also be used as a raw material to produce alum (aluminium sulphate) (ojewumi et al., 2018) and silica (rahayu et al., 2018). the cfw had similar chemical compositions compared to that of the kaolin. the only difference was of the amount of the major components silica and alumina that can be seen in the table 2. the increment of silica and the decrement of alumina values can be explained by the acid leaching of the kaolin. awash melkassa chemical factory prepares alum from kaolin by leaching most of the alumina out of it with sulphuric acid at high temperature and pressure (162°c, 4 bar).the alum is dissolved why the residue (cfw) is discarded. table 1: chemical composition of ethiopian kaolin table 2: chemical composition of the cfw the amount and the quality (absence of impurity) of silica found using acidic route was better, albeit not significantly, than that of basic route. the smaller of silica may be due to loss of silica as sodium silicate in filtration step in the basic route and the loss in quality may be due to presence of metal oxide impurity or possible formation of sodium aluminate as a by-product in the basic route which is an impurity latched on the surface of the silica. the morphology of the basic silica (bs) powder was investigated using scanning electron microscopy. the sem images reviled an irregular shaped agglomeration of the micro particles, when viewed around 25,000 x magnification in figure 3b. the particle size was measured using image j-software. it was found that the particles had an average size of 112 µm. the agglomeration of the particles may be due to the impurities found in the sample. this may have risen from the deposition of unwashed sodium acetate or sodium aluminate on the particles or impurities from planetary ball mill which cannot be removed even after repeated washing. chemical compound composition (weight %) sio2 57.633 al 2o3 37.766 fe2o3 0.86 mgo 0.596 cao 0.346 k2o 1.801 tio2 0.605 p2o5 0.311 chemical compound chemical composition (weight %) sio2 68.633 al 2o3 17.766 fe2o3 0.86 mgo 0.596 cao 0.346 k2o 1.801 tio2 0.605 p2o5 0.311 robel mehari et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 65 figure 3: the sem images of silica micro particles in different resolution of (a) 500 µm, (b) 200 µm, and (c) 100 µm. figure 4: xrd analysis of three samples, chemical factory waste (cfw), basic step silica microparticles (bsnp) and acidic step silica microparticles (asnp). figure 4 shows xrd pattern of the silica particles, the sharp peaks at the angles below 20o might indicate the crystalline phases of alumina in the cfw. this can be further observed by their disappearance in the acidic silica micro particles. sharp spectrum appearing at 2θ = 22, might indicates the crystalline phases of silica present in both the cfw and acidic route silica novel particles (asnp). the disappearance of the sharp peaks and the softness of the band at the basic route silica novel particles bsnp might indicate the presence possible impurities and the amorphous nature of the silica micro particles prepared in the basic route. amorphous impurity in the crystalline material may cause shift in the peaks of xrd pattern and change in robel mehari et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 66 intensity of peaks. there may be change in bond length and bond stretching. the xrd compatibility test done on a software shows the samples are most probably kaolin and silica. 4. conclusion in this work silica was synthesized in 2 methods, named acidic and basic route. the synthesized silica was characterized using sem and xrd. using the acidic routine silica was synthesized successfully with accuracy of 99% match and this was found with the aid of xrd. 20 μm, 50 μm, 100 μm, 200 μm and 500 μm particle size of silica was produced, using a planetary ball miller. in both routes some agglomeration had been seen on the particles this result is found from xrd and sem. from this, it can be concluded that there is small amount of impurities in the product that leads to agglomeration of the product. this may be due to the adhesion of impurities like iron oxide and alumina into the chemical structure of silica. besides that the acidic route showed better quality of silica in terms of color smaller amount of impurity deduced from the xrd analysis. this shows the fact that silica can be prepared from chemical factory waste and leaching with acid gives better yield. acknowledgment this work was done with the help of chemical and materials engineering departments as well as biology department in adama science and technology university. chemicals and synthesis materials were supplied from chemical engineering department while sem microscopy was done in biology department and xrd crystallography was done in materials engineering department. the researchers would like thank these departments immensely. reference anuar, m. f., fen, y. w., zaid, m. h. m., matori, k. a., & khaidir, r. e. m. (2018). synthesis and structural properties of coconut husk as potential silica source. results in physics, 11. https://doi.org/10.1016/j.rinp.2018.08.018 bahari, a., sadeghi-nik, a., sadeghi nik, a., & sadeghi nik, a. (2011). investigation of nano structural properties of cementbased materials. american journal of scientific research, 25. espíndola-gonzalez, a., martínez-hernández, a. l., angeles-chávez, c., castaño, v. m., & velasco-santos, c. (2010). novel crystalline sio 2 nanoparticles via annelids bioprocessing of agro-industrial wastes. nanoscale research letters, 5(9): 1408–1417. https://doi.org/10.1007/s11671-010-9654-6 fleming, j. r., kemkes, d., chatten, r. g., creshaw, l. e., & imbalzano, j. f. (n.d.). pharmaceutical and biotechnology processing : moving into the 21st century. dupont fluoroproducts, 1–10. kasaai, m. r. (2015). nanosized particles of silica and its derivatives for applications in various branches of food and nutrition sectors. in journal of nanotechnology, 2015. https://doi.org/10.1155/2015/852394 moosa, a., moosa, a. a., & saddam, f. (2017). synthesis and characterization of nanosilica from rice husk with applications to polymer composites green synthesis of nanoparticles view project exfoliated graphite view project synthesis and characterization of nanosilica from rice husk with application. american journal of materials science, 2017(6): 223– 231. https://doi.org/10.5923/j.materials.20170706.01 ojewumi, m. e., adeoye, j. b., & omoleye, j. a. (2018). development of alum from kaolin deposit using response surface methodology. moj bioorganic & organic chemistry, 2(3): 166–169. https://doi.org/10.15406/mojboc.2018.02.0075 okoronkwo, e. a., imoisili, p. e., olubayode, s. a., & olusunle, s. o. o. 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(2019). extraction and characterization of bio-silica from sugar cane bagasse ash of wonji sugar industry, ethiopia. international journal of research and analytical reviews, september. www.ijrar.org thio, r. p., konan, d. k., koffi, b. k., & yao, a. k. (2020). characterization of raw silica sand from the ivorian sedimentar y basin for silica glass making. 2508(12): 2016–2024. vaibhav, v., vijayalakshmi, u., & roopan, s. m. (2015). agricultural waste as a source for the production of silica nanoparticles. spectrochimica acta part a: molecular and biomolecular spectroscopy, 139: 515–520. https://doi.org/10.1016/j.saa.2014.12.083 woronko, b. (2016). frost weathering versus glacial grinding in the micromorphology of quartz sand grains: processes and robel mehari et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 67 geological implications. sedimentary geology, 335. https://doi.org/10.1016/j.sedgeo.2016.01.021 zaky, r. r., hessien, m. m., el-midany, a. a., khedr, m. h., abdel-aal, e. a., & el-barawy, k. a. (2008). preparation of silica nanoparticles from semi-burned rice straw ash. powder technology, 185(1): 31–35. https://doi.org/https://doi.org/10.1016/j.powtec.2007.09.012. https://doi.org/10.1016/j.sedgeo.2016.01.021 46 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper indigenous democratic governance in the horn of africa: some reflections on the democratic principles and political significance of gadaa governance kena deme jebessa ambo university, college of social science and humanities, p.o box 19, ambo, ethiopia article info abstract article history: received 12 april 2022 received in revised form 25may 2022 accepted 16 june 2022 the gadaa governance system is the political governance in which suppression and exploitation by the ruling is strictly forbidden as well as considered as wicked. this study was aimed at examining the indigenous gadaa governance system in light of western democratic ideologies and principles. to this end, the study utilized qualitative approach and extensive literature appraisal which is supported by existing document analysis. the study revealed that the gadaa system serves as the basis of a democratic political system. it also showed that gadaa governance is a feasible constitutional replica in this 21st century. the oromo gadaa system has strong democratic elements that concern with all spheres of the nation. consequently, this study clearly point out the need to amalgamate the ideology of gadaa governance system in the constitution of the state. finally, this paper argues that revitalization, institutionalization and rehabilitation of this indigenous democratic governance system can contribute better in the democratization process of the state as well as the peace and stability of the oromo nation and horn of africa. keywords: democratic governance gadaa system oromo nation african democracy 1. introduction before the formation of modern ethiopia, the oromo nation, one of the african indigenous societies, used the gadaa system of governance to organize and order their society around political institutions. it helped oromo nation to turn out to be self-governing and well thoughtout both politically and socially in order to promote the oromo nation wellbeing as well as autonomy (assefa jaleta, 2012). however, the political process that was set into motion by the mid-19th century to the area of the zemene mesafint was able to produce a full of ledged monarchy (levine, 1974) which brought appalling system of discrimination and inequality for more than a century. after modern ethiopia emerged at the closing years of 19th century, however, oromo nation started both internal and external protest demanding eagerly for their e-mail: kena.deme@yahoo.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.455 indigenous governance system. by its very principles and ideologies of governance, it is a designed indigenous governance system exceeding contemporary democratic system (asmarom, 2006). most of all, it is a balancing governance instrument not merely for the wellbeing of aboriginal peoples but also for the nonviolent coexistence of nature as opposed to a supremacy of a single political society, especially the western democracy. specifically speaking, most of the indigenous gadaa institutions of governance are more democratic in several aspects than the imported western style governance principles for the reason that no one size shoe fits all. more important from political stand point, the democratization process of a given state would be more fruitful if it only considers indigenous knowledge and http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.455 kena deme ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 47 governance. this is so because indigenous governance builds trust between the ruler and the ruled. there is a relationship between trust, indigenous governance and democratization. a good example to be noted here is the degree to which greek and united states society were characterized by generalized social trust, directed at both the government and fellow citizens. both states have been home to republican democracy; both are notable because they are successful in practicing democratization process. however, there is a failure in giving realistic recognition to oromo indigenous knowledge in general and oromo indigenous governance called gadaa in particular. as at present discourse, the expression of gadaa governance system is interchangeably used with stipulations of traditional governance and/or local governance which bound its importance in the political culture and governance ideology. according to sharma (1993), in order to make democratization process triumphant, government and governance structure should be part and parcel of the society. in this regard, based on his work, it is possible to make out that the gadaa governance system is an indigenous governance that can more organizes and governs oromo nation on one hand and speed up the democratization process on the other hand. it is thorny to leave out the political and social issues of the oromo from the principles of gadaa system. for instance, some scholars (asefa jaleta, 2012) note that the gadaa system organized the oromo people in an all-encompassing democratic republic even before scholars arrived from europeans with the intention of building democracy. moreover, there are different studies (pankhurst, et al. 2008) undertaken so far on democratization process and democratic governance by different scholars. however, almost all of them are concerned with controversial issues of human rights and democracy without giving focus on the role of indigenous governance. and most of them, yet, remain within the neowestern conceptions of governance and fail to recognize the indigenous democratic governance system. and some scholars (nikolas, 2010 and leus, 2006 as cited in habtamu disasa, 2017) at different times argued for and against the indigenous governance of oromo gadaa system. above all, the gadaa indigenous governance system is criticized in relation to its failure to cover all democratic ideology of governance, composition involvedness, gender inconsiderateness and political significance in democratization process. here it is possible to argue that they have approached the study of gadaa governance with different academic backgrounds and cultural orientations, as a result, diverse interpretation of its principles and standards possibly will increase. at a standstill, some attempted to reduce the scope and content of gadaa governance system to the spiritual globe without any recognition to its multi-dimensional administrative political spheres (habtamu disasa, 2017). for instance, asmarom (2000) states that gadaa institution is one of the famous indigenous african institutions that deals with aspects of human society which is limited to economic, ritual and military. asafa (2007) although noted that the oromo had an unrestricted system of indigenous governance institutional structure, the focus of the study is given on the role of gadaa system in conflict resolution without addressing the democratic elements of gadaa governance. likewise, tenna (2009) argued that the gadaa system is intricate, all-inclusive and convenient system. however, in his work the role of indigenous governance, specifically, gadaa governance in relation to democratization process is not premeditated. despite the fact that asmarom (2006) demonstrate the fact that the gadaa governance structure is a political governance system with strong self-governing basics, the nexus between democratization process and gadaa governance on one hand and political significance of gadaa governance on the other hand is not addressed. in fact, there are some writers who consider the gadaa system as spiritual practices alone and hence try to undermine its political significance. hinnant, for example, views this system as politically irrelevant, playing ritualistic roles only (hinnant, 1978). these scholars disregard the function of gadaa governance system in each aspect of the oromo nation which also includes politics, environmental, religious and philosophical aspects. this and other related factors made the existing literature on gadaa system too general. so, by taking into consideration all these points, conducting this study is firmly imperative. kena deme ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 48 2. methodology with the aim to scrutinize democratic principles and political significance of the gadaa governance in the horn of africa, this study employed a qualitative approach. the study adds to the existing discourse on the subject by examining the democratic principles and political significance of gadaa governance. this rationale is initiated from the writer‘s hypothesis that unlike western democracy, there are untouched democratic values in the gadaa system which can solve governance crisis but not appropriately and effectively used by the government and institutions. to achieve this objective, qualitative research approach is better for the reason that it attempts to interpret phenomena in terms of the meanings people attach to them (creswell, 2003). in other words, qualitative research is, basically, interpretive in that it involves analyzing data and finally making interpretation or drawing conclusions about the data analyzed (ibid). accordingly, secondary data that were collected through a systematic reading of books, journal articles, reports and credible internet sources are qualitatively interpreted and analyzed. given its broad and complex socio-political aspects of the gadaa governance system, the scope of the study is delimited to its democratic principles and political significance. 3. results and discussion 3.1. gadaa governance system as better option: does it convincing? some scholars assume that gadaa governance system has some democratic discrepancy by depending on limited number of studies which hardly focus on its governance structure and system (assefa; 2008). when comparing gadaa indigenous governance system with modern democratic governance, it is possible to argue that gadaa governance system is a better option of governance. by taking this issue in to consideration, the next focus of our discussion will be identifying reasons that make the gadaa indigenous governance better than the western style based governance and ideologies. the oromo society experiences a sense of possession and considers the gadaa governance system as their worth (tenna dewo, 2008). the wisdom of belongingness is innate to people’s outlook. thus, it is more than simple political directive. in contrary to this, in western governance system, citizens think the arrangement as pure political governance (abanyam, 2013) and even search to see other possible options. this clearly shows that they externalize the western governance system rather than internalizing it. in addition to this, gadaa governance system has multifaceted interconnection with civilization, custom, standards and societal faith of oromo society that its leadership is considered as a principled administration rather than political governance. however, as far as western democratic governance is considered, people do not consider it as their shared worth. they perceive it mainly as influential regulation, lawful reflection or legal provisions. in gadaa governance system, political decisions are made by principled stipulation whereas in western governance, political decisions are almost subject to the authorized guideline as well as political calculations (gufu oba 1996). practically, qallu is the moral side of governance that is consistent with other gadaa institutions and important in the check and balance of power. unlike western governance which is inaccessible to the local communities, gadaa governance system is easily accessible to the local community. it is advantageous since it is affordable to the constituent of oromo community. additionally, the political game in gadaa governance system stresses the resolution of protagonist with each other rather than making entire winner or loser. here, the concept of oromo community talks may rationalize this truth. in line with this, the socio-political sentence aims not at revenge but resuming social stability, compensation, confession, resolution, pardon, open-mindedness and nonviolent coexistence (mekuria bulcha 1996). the process of justice running is less costly in view of the fact that individuals have tough decent pledge. by considering these and other related factors it is possible to argue that gadaa governance system is politically smooth and trustworthy procedure of governance system. on the other hand, as far as western governance system is concerned, it establishes right and wrong, winner and loser rather than reconciling the protagonists. thus, there is a political notion of win-lose outcome or total triumph of one group over the other. here the political judgment is aimed at punishment and giving lessons to others the hardest way rather than forgiveness and peaceful coexistence (hinnant john, kena deme ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 49 1978). this indicates that unlike gadaa governance system the western governance system is not based on open consent. even if the socio-political, economic and executive rules and laws do not exist in a written form as a constitution of state in gadaa governance system, it is in the reminiscence of individuals and entrenched in social values of oromo society (ibid). in western governance system, rules and regulations are not socio-politically, culturally and psychologically internalized by individuals. it is also less affordable to the local community that societies feel as it is imposition type of governance system (daniel, 2014). hence, it is possible to argue that when comparing with gadaa governance system; western governance system is a complex and ambivalent bureaucratic procedure of governance system. 3.2. the political dimension of gadaa governance: a look at its democratic implication historically, the oromo people were independent and self-governing nation until the end of the 19th century. as also stated before, indigenous governance play a significant role in building democratization process on one hand and trust between the society and the ruler on the other hand(feldman, 1966). by taking this in to consideration and arguing that gadaa governance system is a democratic indigenous political system of oromo people and other nations, this section points out the political substance of gadaa governance. an important debate is going on relating to whether the gadaa system can practically be applied in the contemporary oromo societies. attitudes significantly differ in this regard. but one issue scholars of democratic governance seem to agree on is that the unswerving model of the gadaa governance system to modern political reality is unthinkable, due to western globalization and the legacies of imperial regimes influence in ethiopia (mohamed; 2013:18). it is evident that it is difficult to say with certainty a given political governance system possesses the characteristics of a democratic implication and possible to implement unless conditions are met and expressed clearly. to be specific, it needs more insightful and appropriately conceived traits that help us better understand the political dimension of the governance system. in our case of gadaa governance, all member of the gadaa stage collectively rose to the highest position of political and social role in the societies. due to this, it connotes a period of eight years. here, what makes this type of political governance attention-grabbing is that in the nature of gadaa governance system, power is not exercised from the center. a part from this, there is balanced representation of all peoples. this indicates the fact that the nature of gadaa governance system is federal state structure. the gadaa leader is called abba gadaa (meaning head of the reign, father of the scepter), (jemjem and dhadach, 2011 cited in tesema ta’a, 2016). in fact, one may inevitably venture into a discussion on other aspects of the gadaa governance ideologies, when he/she intends to study its political implication and dimension aspects. accordingly, if the discussion of oromo gadaa system from its structure perspective is pointed out, we are simultaneously talking about its complex system of political governance. in this case, we can talk of the gadaa system just like when we talk about systems such as democracy and aristocracy. even if there are differences in ideologies, principles and contents, all these systems of governance basically focus on political context of democratizing process of the state. at this point, what we need to be clear with is the concept of democracy, democratic governance and its elements. concerning this discussion, they may vary even among various systems of governance that we often consider as democratic state and not democratic state. for instance, mohammed salih states that democratic governance in general and democratization process in particular is not about the process and procedure of political power shift from one regime to another (2001:20). he rather argued that democratic governance is about political participation, the skill of peoples to articulate their inclination freely and how this is assured according to a given institutional structure and jurisdictional power (ibid). salih’s conception of democratic political governance system would undoubtedly assist us to reveal the nature of autonomous essentials and democratic functionality entrenched in the oromo gadaa political governance system. his conception focuses on limited period of governance, check and balance, values and attitudes of the people that the society elected. and in gadaa indigenous governance, kena deme ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 50 the period of eight years is set as the period of one term of presidency which has its own meaning. at the end of term of presidency which is at every eight years, oromo hold a big and general assembly so as to revisit and revise contents of their laws. in addition to this, the periodic assembly has a power and duty to examine and improve qualities of working rules and regulations. here, the member of the national assembly known as gumii or caffee is made up of all the assemblies and councils of the oromo who review the existing laws and make new laws when needed. in addition to this, they also evaluate the men in power and resolve major conflicts that could not be resolved at lower levels of their judicial organization (asmarom, 2006). saying this with regards to the political notion of gadaa governance system, it is worth to note that this indigenous system has been challenged by different internal and external factors (asmarom, 2006). the existence of factors affecting gadaa governance practice suggests the need to find the possible everlasting solutions to these issues which may include but not limited to institutionalizing the system and incorporating in the rule and regulations of the state. it is evident that there are studies conducted by some scholars (dereje hinew, 2012) which mainly focus on the analysis of the oromo nation gadaa governance system features. hence, there are inadequate studies undertaken to be support that gadaa governance principles has more democratic elements which is even so difficult to find in the republican type of democracy. by considering this, the focus of the next section of this paper would be on the scrutinizing the democratic elements of gadaa governance system. 3.3 the democratic elements of gadaa governance system despite its origin and theoretical disparities, democratic governance has similar subjects and topics of debate in dealing with its indicators (mohammed salih, 2001). these may include; significance, scopes as well as indicators. under this section, this paper will focus on an assessment of democratic governance indicators in gadaa governance system. one indication of democratic governance is free, fair and periodic election. based on this, it is evident that gadaa governance refers to the eight year period of government. there is also clear division of power and responsibilities. concerning this, the gadaa governance system is a multifaceted system in which the oromo are divided into different patties and take part in political, military and cultural affairs (baissa, 1971). all party had detailed function and purpose to perform in five periods of eight years each. what happen at the end of political regime change also determines to what extent the procedure and process is democratic and all inclusive (daniel, 2014). accordingly, in gadaa system at the transfer of power, the waiting party would hold ceremonies and become the ruling party for a period of eight years. the leaders of the previous retired into an advisory role while the new leaders were entrusted with defense and governance of the oromo nation. its leaders exercise full decision-making power and responsibility regarding military and civil matters affecting the oromo. when it comes to the other focus of democratic governance, the central attention of any study is the process of law making and law enforcing. in line with this, there are three organs within a gadaa governance system that are ethically, politically and functionally interdependent. in addition to this, different scholars considered the oromo gadaa system as a greatly developed autonomous political and legal system. for instance, pankhurst and getachew, (2008:28), as well as asmarom (1973:31), similarly argued that the institutional governance and conflict management in the oromo people is processed by independent but interconnected organs such as the gadaa judicial or dispute settlement, the qalluu (spiritual leader) and the gumii which mean national assembly. here, it is obvious that the three systems are mutually supporting and it is difficult to understand one without the others. consequently, often such a tough and in depth sociological and anthropological research of some of the above scholars in general and asmarom in particular considered the gadaa system as a democratic political and military system with strong democratic elements manifested throughout selected political leaders (tesema ta’a, 2016). due to this, we can argue that what makes the democratic quality of the gadaa system more strong another way from a variety of systems of governance is oromo people take and internalize gadaa governance as value, identity and ways of life. it is so because it is difficult to argue that all principles of kena deme ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 51 western democracy are gracious with african worldview. specifically, some of these western principles have rather helped to lessen the african civilizing principles. marco bassi (1996) point out some important implications of the gadaa governance system which is possible to declare basic to modern oromo politics in particular and horn of africa in general. one such significance is the participatory approach from down to top that he believes can be extended to modern oromo polity. the extensive dialogue through which consensus under the gadaa system is reached is an exemplary participatory leadership. here it is also possible to highlights not only political participatory system of good governance but also the economic significance as the gadaa model could be taken as a inspiration to keep both the resources controlled by the center and the powers delegated to the political center as limited as possible, in order to reduce competitions. this has been one of the major causes of devastating interethnic conflict in post-colonial africa states. consequently, asafa (2007) also notes that gadaa governance system was based on the principles of check and balance, division of power, balanced opposition and power sharing between higher and lower administrative organs which prevent power from falling into the hands of despots (asafa 2007:48). a part from the above discussions, the notion of freedom which western scholars and philosophers (john locke, 1962) used to put at the midpoint when they discuss democratic governance and democratization process of the state is also critical. when it comes to the case of gadaa oromo, it is tricky to disconnect individual freedom from social freedom. for instance, in this indigenous governance system there is a principle known as saala-fokko which identifies individuals with society and considers them as one and the same. this relation is not simple legal necessary in the sense we know today, but rather realistic decent binding that have embodied the courage of unity, universal identity, and common internal peace. finally, it is also important to note that the gadaa system is not only apolitical democratic system centered on humans but it also encompasses the value of nature which also safeguards the natural environment. the oromo gadaa system promotes democratic customs (asmarom, 1973, workineh, 2005) and contains requirements for the security of the rights of both human being and non-human species. the bonds between the environment and the people are not only material but also spiritual and moral (workineh, 2002). from its nature, it is possible to argue that there is a clear and close corresponding relationship between the gadaa governance system and republican principles of governance. however, at the same time there are democratic elements which are found in gadaa indigenous governance but not in western style democracy. 4. conclusion and recommendations in this study, we have discussed that the oromo had democratic and civilized type of governance system that developed their own cultural, religious and political institutions and shaped their history. it indicated that the oromo nation have an all-encompassing socio-cultural, moral and political guide unified under the given of gadaa political governance. they constitute their whole ethical life as the mirror of all other aspects; such as economic, norms, politics and conception of truth that holds them together. the oromo practice all these aspects of life at various stages of socio-cultural practice across generations. based on this study, it is possible to outline different critical principles of gadaa governance system which are even missed in discussion of republican democratic governance of western democracy. this principle of governance includes but not limited to balanced opposition, periodic succession, democratically ranked social structures, the principles of accountability and the principle of seniority and succession. there is no doubt that these principles of indigenous governance can serve as the foundation to which modern ideas and practices of development could be incorporated. in contrast, the recent gadaa system development is operating only as one part of the culture of the oromo people, but not as an independent political system which needs further academic and research works. finally, it is evident to argue that as gadaa governance system is innate to the horn of african in general and to ethiopia in particular, it helps to maintain the norms, values, morality and the general culture of indigenous people. this enables the country to pursue a stable peace and development easily. hence, the kena deme ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 52 government should encourage the development of indigenous governance system that is consistent with the nation cultural values. in this way, the state can move away from the existing governance crisis and adverse effects of western democracy. acknowledgments i would like to express appreciation to all anonymous reviewers for their constructive comments and recommendation starting from the first draft of this manuscript. reference asafa jalata. 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(2005). the rehabilitation of indigenous environmental ethics in africa. journal of diogenes, 52(3):1734. 32 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu research paper evaluation of sorghum genotypes and reduced rates of fungicide application against anthracnose (colletotrichum sublineolum) management in arba minch and derashe districts, southern ethiopia getachew gudero mengesha, tariku simion dojamo, melese lema tesema, dizgo chencha cheleko southern agricultural research institute, arba minch agricultural research center, p.o.box. 2228, arba minch, ethiopia article info abstract article history: received 23 may 2020 received in revised form 15 february 2021 accepted 24 february 2021 anthracnose disease caused by colletotrichum sublineolum is a major constraint that limits the production and productivity of sorghum in ethiopia. a field experiment was carried out in arba minch and derashe during the 2018/19 cropping season to determine the integrated effects of genotypes and reduced rates of fungicide applications on anthracnose disease, growth and grain yield of sorghum. the treatments were composed of four sorghum genotypes and three different rates of ridomil gold mz 63.5% wp (ridomil), including unsprayed and laid out in randomized complete block design with the factorial arrangement in three replications. significant (p < 0.001) difference was observed in the magnitude of disease and crop parameters measured among the treatments considered. the disease severities were 22.78, 29.44, 62.22, and 66.11% on arghiti, melkam, seredo and local cultivar, respectively, because of a combination of ridomil at the rate of 3 kg ha-1. these treatment combinations exceedingly reduced area under the disease progress curve and rates of disease progression as well. no statistically significant difference was observed on the grain yield obtained from plots sprayed with ridomil at the rates of 2 and 3 kg ha-1 at 14 days intervals. a yield loss of 54.41% was recorded on unsprayed plots of the local cultivar as compared to well-managed plots of other genotypes. the use of arghiti and melkam in combination with ridomil at the rate of 2 kg ha-1 was found to be relatively efficient in reducing anthracnose development and gave higher grain yield as compared to the unsprayed plot. therefore, the use of arghiti and melkam in combination with application of ridomil at the rate of 2 kg ha-1 for the management of anthracnose could be suggested to sustain the production and productivity of sorghum for the farmers in the study areas and in similar agro-ecology. further studies should be conducted in similar and other agro-ecologies in ethiopia for at least one more year with over location to reach a concrete recommendation. keywords: anthracnose grain yield rates of ridomil severity sorghum genotypes 1. introduction sorghum (sorghum bicolor l.) is one of the important cereal crops for a larger section of people in tropical and subtropical countries (fao et al., 2018; usda, 2018). it is ranked 5th most important cereal crops grown after wheat, rice, maize, and barley worldwide (faostat, 2017). it is the staple indispensable food crop for millions of people throughout the arid and semi-arid regions of the world (faostat, 2017). the crop is a corresponding author, e-mail: gechnig@gmail.com https://doi.org/10.20372/ejssdastu:v8.i2.2021.262 major food and nutritional security for millions of people in eastern africa (gudu et al., 2013) due to its production under the drought-prone condition and other restraints, where other crops can no/little survive (adugna, 2007; seyoum et al., 2019). in ethiopia as well as in the southern region of the country, it is ranked on 3rd and 4th cereal crops grown in terms of the areas of http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i1.2021.............. getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 33 land allocated, the volume produced and the number of farmers engaged in its production (csa, 2018). however, in the country as well as in the southern region, the production and productivity of sorghum were curtailed by various biotic and abiotic factors. due to these factors both the national (2.53 t ha-1) and the regional (2.23 t ha-1) including the study areas (1.54 t ha1) (csa, 2018) average productivity of sorghum is far very low as compared to the world productivity (5.88 t ha-1) (usda, 2018). among the biotic factors, diseases are the most important one, of which anthracnose disease caused by colletotrichum sublineolum, is the most important and production bottlenecks, and responsible for low productivity per unit area in sorghum production systems (casela et al., 1997; thakur and mathur, 2000; binyam et al., 2016). the epidemics cause significant yield loss of 50 to 100% (thakur and mathur, 2000; tesso et al., 2012). yield losses due to anthracnose infection are typically interconnected with a reduction of grain size due to the interference of normal physiological functions as a result the infection affects the grain development of the crop (thakur and mathur, 2000). anthracnose had been reported in most sorghum producing areas of the world. however, it was regularly observed in tropical or subtropical environs where it is prevalent and sparingly important under high humid and warm temperatures (hess et al., 2002; ngugi et al., 2000). in ethiopia, anthracnose is prevalent all over the county, particularly in the low and mid-lands of the country (chala et al., 2010; binyam et al., 2016; girmay et al., 2019). the periodic epidemics caused significant yield losses in the country. in spite of being an important disease of sorghum and it has potential to cause significant yield losses, anthracnose management was generally not common in ethiopia. particularly in arba minch and derashe areas, a little effort has been made in the use of resistant genotypes as a result of the disease became epidemic year after year in these areas and causes considerable grain yield losses. however, different management options are available to manage anthracnose and attempts have been made worldwide through different cultural procedures, use of resistance sorghum genotypes and fungicide application (casela et al., 1997; marley, 2004). a resistance source to anthracnose is the most preferred management option in sorghum production systems. however, the use of resistant genotype is not guaranteed for a year after year production due to the durability of the resistance gene and the wider variability of the pathogen itself, which are after sometimes may cause to breaking down of the resistance gene and lead the genotype to susceptible for the disease (agrios, 2005). this phenomenon might probably be associated with climate change and the continuous production of sorghum year after year in the study areas. despite continued efforts have been made so far to develop genotypes with either disease escape traits or specific disease resistance genes, fungicides are the only effective method for management of most of the diseases in many crop pathogens (agrios, 2005; foster et al., 2017). management of anthracnose through fungicide application is used in some parts of the country (moa and eata, 2018) and the study areas as well, which was done unwisely under field condition, below or over recommended rates and frequency, untimely and indiscriminately whatever fungicide they find in their areas. however, unwise use of fungicide has adverse effects on the crop, health of human and other living organisms found in the kingdom animalia, pollute the environment and also lead to the development of resistance by the pathogen (green et al., 1990; who, 2004; agrios, 2005). therefore, designing appropriate management procedures and information regarding factors that influence the intensity of the anthracnose is a prerequisite for the study areas and the country as well. use of the integration of host genotypes and fungicide application is the two principal approaches in the integrated management of anthracnose strategy implemented in most sorghumproducing areas of the world (marley et al., 2005; gwary et al., 2008). previous researches on different crops (wheat, maize, sorghum, common bean, potato, tomato, and onion) had been indicated that the use of host resistance in a combination of fungicide application reduced disease suppression and could provide more than a 10% yield increase relative to the untreated ones (gwary and asala, 2006b and 2006c; foster et al., 2017). different genotypes respond differently to plant diseases due to the genetic makeup of the genotype and a combination of genotype and appropriate type, rate and time of fungicide application is required to reduce the disease effect and to maximize yield. reports on the integration of genotypes having a different level of resistance to the disease and fungicide application with getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 34 different levels of rates indicated that the action of a fungicide might vary with the rates used on the genotype to manage the disease. similarly, genotypes having different levels of reaction to a given pathogen may respond well with low or medium or higher fungicide rates (datnoff et al., 2001; agrios, 2005). a genotype that will perform well with low or medium rates of fungicide will be preferable to a genotype that requires more fungicide rates. no or little recognition of the farmers in managing anthracnose, absence of research works previously in the study areas through a combination of sorghum genotypes and reduced rates of fungicide application and due to the above reasons this study was necessitated. therefore, the objective of the study was to determine the integrated effects of genotypes and reduced rates of fungicide application on anthracnose, growth and grain yield of sorghum in arba minch and derashe district, southern ethiopia. 2. materials and methods 2.1. description of experimental areas a field experiment was carried out in arba minch and derashe district southern ethiopia during the 2018/19 cropping season. these areas were selected based on the recurrent occurrence of the disease and its importance in sorghum production systems. the geographical position of the specified areas was 06° 06’ 841’’ n and 037° 35’ 122’’ e at arba minch and 05° 31’ 31’’ n and 037° 25’ 46’’ e at derashe. the areas were far apart from each other with a distance of 80 km, along the accessible vehicle road. the sites are positioned at an altitude of 1216 and 1253 meters above sea levels at arba minch and derashe, respectively. the two locations exhibit a bimodal rainfall pattern from march to april and from august to november. arba minch and derashe receive an average annual rainfall and temperatures for the last decade were 750 mm and 27.50°c and 810 mm and 25.68°c, respectively. the details of weather data during the 2018 cropping season is shown in table 1. arba minch is characterized by moderately alkaline with low organic contents (1.05%) and black sandy-loam in the soil type. moderately alkaline with high organic content (8.82%) and black clay-loam in the soil type is the basic characteristic features of derashe (moanr and eata, 2016). 2.2. experimental material the experiment was entirely executed in an open environment to ensure disease occurrence and augment natural infections at the beginning of the experiment. four sorghum genotypes (arghiti, melkam, seredo, and local cultivar) differing in their resistance levels to anthracnose had used as a varietal component. the genotypes are currently under production in the study areas and showed different levels of reactions to anthracnose under natural epiphytotic conditions. seeds of the sorghum genotypes were obtained from melkasa agricultural research centre, ethiopian institute of agricultural research, ethiopia, and farm-saved (local cultivar). the genotypes had developed mainly for drought-tolerant with high productivity and quality. the details of agro-ecological, agronomic, and disease reaction characteristic features of the evaluated sorghum genotypes had presented in table 2. in addition, fungicide, ridomil gold mz 63.5% wp [metalaxyl 8% + mancozeb 64% wp] (systemic type) with three spray rates (0.0, 2.0, and 3.0 kg ha-1), was used as fungicidal component. the fungicide was selected due to the systemic effect against anthracnose through translocation within the plant tissues. table 1: monthly mean minimum and maximum temperature and total rainfall at arba minch and derashe in southern ethiopia during the 2018 cropping season location weather variable jan feb mar apr may jun jul aug sep oct nov dec arba minch maximum(oc) 29.84 30.70 28.66 26.75 26.42 24.78 25.52 26.84 28.68 27.86 28.62 28.94 minimum (oc) 15.81 15.85 17.94 17.34 17.86 17.04 18.44 18.26 17.73 17.95 16.75 17.35 rainfall(mm) 0.00 47.60 35.50 250.70 165.0 89.00 12.80 94.40 159.40 102.6 81.00 17.76 rh (%) 35.84 39.32 58.77 66.12 64.13 50.56 44.12 63.35 69.11 60.34 57.45 16.34 derashe maximum (oc) 26.73 25.30 26.20 25.51 26.67 27.20 27.70 27.67 27.67 26.60 26.44 26.93 minimum (oc) 13.40 12.59 13.35 13.28 13.35 12.92 13.15 13.02 13.25 12.49 12.38 13.01 rainfall (mm) 37.00 28.00 48.80 204.00 170.0 164.4 85.00 96.00 96.00 319.6 186.8 32.60 rh (%) 36.05 35.17 50.25 60.44 59.04 46.17 36.15 48.35 56.14 48.08 37.67 30.11 source: the meteorological data were obtained from national meteorological agency at hawassa branch in the year of 2018. rh = relative humidity. getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 35 table 2: the details of agro-ecological conditions*, agronomic characteristics and breeding center of sorghum genotypes used for the study at arba minch and derashe in southern ethiopia during the 2018 cropping season sorghum 1 genotypes pedigree year of release flowering dates maturity date plant height (cm) productivity t ha-1 reaction to anthracnose research farmer arghiti wsv387/p9403 2016 79 125 200 3.78 r melkam wsv387 2009 76-82 118 126-163 3.70-5.80 3.50-4.30 mr seredo seredo 1986 60-70 90-120 120-150 3.00-5.00 s local cultivar 65-75 110-120 120-170 hs 1releasing center is melkassa agricultural research center, ethiopian institute of agricultural research. * the suitable agro-ecology for the sorghum genotypes are dry lowland with an altitude of < 1600 m.a.s.l., the range of temperature of 27 to 32 oc and annual total rainfall of < 600 mm. r = resistance; mr = moderately resistant; s = susceptible; hs = highly susceptible. source: data were sourced and organized from moanr (2016) and moa and eata (2018). 2.3. experimental design and agronomic practices the design of the experiment was a randomized complete block design in a factorial arrangement with three replications. a total of 12 treatments have comprised during the experiment, four sorghum genotypes and three rates of ridomil application. the treatments were assigned randomly to experimental plots within a block. planting was done with the recommended rates of sorghum (10 kg ha-1) on 18 march 2018 for both locations. the layout was designed with 14 m width x 45.30 m length with a unit plot size of 3.0 m width x 2.4 m length. the plots spaced at 1.5 m and blocks separated by a safeguard path of 2.5 m to prevent drifts’ effects. there were five rows within plots and spaces between plants and rows were maintained as 15 cm and 75 cm, respectively. each row consists of 16 plants. nps (100 kg ha-1 for both locations) and nfertilizers (100 kg ha-1 for arba minch and 50 kg ha-1 for derashe) had used for nutrient management. weeding and other cultural practices were implemented to all plots manually as per the recommendations suggested by moa and eata (2018) for both locations. foliar application of ridomil had carried out with the prearranged rates for each treatment combination at 14days intervals. unsprayed plots were left for each genotype as a control to consent to maximum disease development. the first fungicide spray was taking place at 46 and 42-days after planting (dap) at arba minch and derashe, respectively. spraying of fungicide was performed using a manual knapsack sprayer calibrated to convey 500-700 l of water ha-1. three consecutive sprays had practiced for each treatment at both locations. 2.4. disease assessment disease incidence and severity were scored at 14days intervals before each spray rate of fungicide starting from the first appearance of the disease. a total of six assessments have executed during the experiment at both locations. disease incidence (pdi) has scored by the rating of diseased plants per total number of plants assessed within the plot in the three central rows and expressed as in percent. disease severity was scored visually from 15 pre-tagged plants per plot following the scale designated by thakur et al. (2007), where, 1 = no visible symptoms or presence of chlorotic flecks, 2 = 1 10% leaf area covered with hypersensitive lesions without acervuli, 3 = 11 25% leaf area covered with hypersensitive and restricted lesions with acervuli in the center, 4 = 26 -50% leaf area covered with coalescing necrotic lesions with acervuli and 5 = > 50% leaf area covered with coalescing necrotic lesions with acervuli. disease severity scales were transformed into percentage severity index (psi) for analysis following the formula suggested by wheeler (1969) as below: psi = sum of numerical ratings no. of plants scored x maximum score on scale x 100 the area under disease progress curve (audpc), the development of disease on a whole plant or part of the plant during the epidemic periods, was figured out from psi values assessed at different days for each plot using the formula suggested by campbell and madden (1990) as below: audpc = ∑ 0.5 (𝑋𝑖 + 𝑋𝑖+1) 𝑛−1 i =1 (𝑡𝑖−1 − 𝑡𝑖 ) getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 36 where, n is the total number of disease assessments, ti is the time of the i th assessment in days from the first assessment date and xi is the psi of disease at the i th assessment. audpc was articulated in %-days since severity (x) is expressed in percent and time (t) in days. the rate of disease progress (rdp) was assessed by repetitive assessment of the percentage of leaf area infected by anthracnose in each plot, starting from the beginning of the disease. logistic, ln [(y/1-y)] (van der plank, 1963), and gompertz, -ln [-ln (y)] (berger, 1981) regression models were compared for the goodness of appropriate in the assessment of disease progression from each treatment. the logistic model showed greater expression as indicated by a higher coefficient of determination (r2) and lower standard errors for most of the parameters. then, the data were regressed over time, and the apparent rates of disease progression had derived via the following logistic regression equation: 𝑌𝑡 = 1 1 + exp − ln[ 𝑌𝑜 1−𝑌𝑜 ]+𝑟𝐿𝑡 where, yt: percentage of severity at t th assessment date; yo: percentage of initial severity at t th assessment date; ti: time of the i th assessment in days from the first assessment date; and rl: the rate parameter determined by the production of inoculum by infected individuals/ lesions per unit area of diseased tissue. the rate of disease progress was expressed in unit days-1. 2.5. crop parameters assessment the three central rows of each treatment within the plot were looked over for the determination of growth and yield-related parameters. numbers of productive plants per plot, grains yield, and thousand seed weight were considered for crop parameters during the experiment. the number of productive plants per plot had measured as counting of the stand productive plants within the plot. harvesting of sorghum grain was undertaken on 144 and 150 dap at arba minch and derashe, respectively. the harvested grain yield was converted into t ha-1, and a thousand seed weight was also measured in gram (g) for each treatment. the harvested grain yield was adjusted to 12.50% moisture content following the procedure suggested by taran et al. (1998). thousand seed weight was measured from randomly sampled grains obtained from the total harvested grains of each plot and adjusted them to 12.50% moisture content. 2.6. data analysis analysis of variance was carried out for the measured disease and yield-related parameters to determine the treatment effects following the general linear model procedure of the sas software version 9.2 (sas, 2009). the two locations are considered as different environments. as the f-test of the error variances for the studied parameters for the two locations was homogeneous, the data had combined for the analysis. mean separations between treatments have performed using fisher’s protected lsd at a 5% probability level following the procedure described by gomez and gomez (1984). correlation of disease and yield-related parameters were determined using the determined pearson correlation coefficient (r). likewise, the relationship between the disease and grain yield was analyzed using linear regression of the audpc and grain yield for estimating the yield loss in sorghum production. regression was estimated using minitab (release 15.0 for windows r, 2007). 2.7. determination of economic feasibility and relative yield loss before applying partial budget analysis, statistical analysis has done on grain yield of sorghum to relate the mean yield between treatments, as a result, significant differences had observed between treatment means. economic feasibility and relative yield loss was determined from the pooled data obtained from the two locations following the procedure suggested by cimmyt (1988) and robert and james (1991), respectively. the economic analysis was done based on the fixed and variable cost of production. the fixed cost includes the current value of land rent, whereas the variable cost included current fungicides, labor (fungicide application, weeding practices, sowing, and harvesting), and the market price of sorghum grain. the information was acquired through personal communication with some farmers who told them that the average unit price of land rent ha-1 for one growing period was $ 246.19 across the locations, depending on the crop type produces during the growing time. the unit price of ridomil was $ 48.88 l-1. the unit cost of the knapsack sprayer was $ 43.53. similarly, the cost of labor for fungicide applications getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 37 was $ 2.82 man day-1. the market average unit price for grain yield of sorghum per ton was $ 288.50 during the study across the locations. all costs and profits are intended on a hectare basis in the us dollar ($). the actual grain yield of sorghum was adjusted downward by 10% to estimate the differences between the experimental grain yield and farmers’ yield could expect from the same treatment. besides, relative percent yield loss was determined from each plot as follows: relative yield loss (%) = 𝑌𝑏𝑡 − 𝑌𝑙𝑡 𝑌𝑏𝑡 x 100 where, ybt is the yield of best treatment (maximum protected plot) and ylt is the yield of lower treatments. 3. results and discussion 3.1. analysis of variance for the studied parameters the mean square of the combined analysis of variance (anova) for the location, genotypes and rates of fungicide application and the results of their respective interactions of the studied parameters are presented in tables 3. the combined anova revealed that there was an interaction effect on all the studied parameters across location, genotypes and rates of fungicide application. all parameters of sorghum were significantly affected by the different sorghum genotypes as well as the rates of ridomil application. this phenomenon indicates the different sorghum genotypes having different levels of reaction to anthracnose similarly affected by different rates of ridomil application in the two locations. all the studied parameters, except for tsw, were significantly affected by location by genotype interaction. for all the studied parameters, except for psif and rdp, no interaction effects were observed on location by rates of fungicide applications interaction. the interaction effects of the genotype and rates of fungicide application of the studied parameters showed that there were significant variations on the disease scores (pdif, psif, audpc, and rdp), but there were no interaction effects on the growth and yield-related traits (npp, tsw, and gy). no interaction effects were detected among the treatments tested for the mean squares of the studied parameters on locations by genotypes by rates of fungicide application interaction, except for audpc (table 3). the main effects implied that each sorghum genotype responded differently to the different rates of fungicide application. likewise, datnoff et al. (2001); gwary et al. (2008); renata et al. (2012) found that significant difference had been observed among the treatments evaluated for the stated and other parameters in their studies on the management of anthracnose through the integration of sorghum genotypes and different fungicide uses under different methods of application. 3.2. effects of genotype and rates of fungicide application on disease development the disease first appeared on seredo and local cultivar at both locations. symptoms conspicuous for anthracnose were observed on leaves and stalk of the stand sorghum at the two locations during the study period. the infection appeared as elliptical or elongated lesions on leaf and stalk, leaf necrosis, premature drying of a leaf, stalk, and poor grain filling on infected plants (figure 1). the leaves on unsprayed plots became rigorously infected and gradually produced abundant acervuli. the plants were defoliated and died after the appearance of the disease symptom on those plots severely infected. similarly, hess et al. (2002); thakur and mathur (2000); gwary and asala (2006a); girmay et al. (2019) reported that symptoms of infected sorghum due to anthracnose, which appeared on the leaf, stalk, panicle and grain with similar features on all the above-ground tissues of the infected sorghum. figure 1: symptoms of c. sublineolum under field condition on an unsprayed plot of seredo (left side) and local cultivar (right side) at arba minch in southern ethiopia during the 2018 cropping season. the highest mean disease incidence (100%) was recorded on all rates of ridomil application on unsprayed plots of seredo and local cultivar as compared to unsprayed plots of arghiti (74.58%) under the integration of sorghum genotypes as well as the rates of ridomil application. conversely, the lowest mean disease incidences (55.83%) have recorded on arghiti getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 38 table 3: mean square of analysis of variance for the studied parameters under the combinations of sorghum genotypes and reduced rates of fungicide applications at the study areas in southern ethiopia during the 2018 cropping season df = degree of freedom; pdif = percent disease incidence at final date; psif = percent severity index at final date; audpc = area under disease progress curve; rdp = rate of disease progress; npt = number of productive tiller; tsw = thousand seed weight; gy = grain yield; l = location; g = sorghum genotype; rof = rates of fungicide application; l * g = interaction effect of location by genotypes; l * rof = interaction effect of location by rates of fungicide application; g * rof = interaction effect of sorghum genotypes by rates of fungicide application; l * g * rof = interaction effect of location by sorghum genotypes by rates of fungicide application; se = standard error; cv = coefficient of variation; r2 = coefficient of determination; * = significance difference at p < 0.05; ** = significance difference at p < 0.01; *** = significance difference at p < 0.001; **** = significance difference at p < 0.0001;and ns = not significant. source of variation df mean square pdif (%) psif (%) audpc (%-days) rdp (unit day-1) npt (count) tsw (g) gy (t ha-1) replication 2 18.84 ns 39.85 ns 8345.79*** 1.14 x 10-6 ns 286.72 ns 13.88 ns 1.97ns location 1 1334.72**** 1291.99**** 184022.22**** 1.66 x 10-4**** 13585.01**** 62.35* 74.51**** genotypes 3 6047.57**** 10966.65**** 3038706.39**** 2.01 x 10-4**** 5459.50**** 333.59**** 37.88**** rate of fungicide 2 375.61**** 1241.01**** 121740.52**** 8.56 x 10-5**** 3619.43**** 435.38**** 6.53* l * g 3 801.39**** 113.11*** 27094.93**** 2.91 x 10-5**** 883.42* 10.16 ns 9.48** l * rof 2 14.15 ns 48.26* 3046.90ns 6.80 x 10-6*** 108. ns 4.81 ns 0.03 ns g * rof 6 207.90**** 55.83*** 15045.79**** 8.44 x 10-6**** 74.02 ns 13.07 ns 0.89 ns l * g * rof 6 45.75 ns 17.50 ns 2847.78* 2.75 x 10-6 ns 17.56 ns 2.89 ns 0.20 ns error 12 10.50 11.08 944.35 9.80 x 10-7 178.31 11.91 0.65 f-value (pooled) 41.28**** 58.49**** 176.57**** 20.28**** 4.37** 3.77** 4.31** mean 84.24 51.37 978.87 0.02 62.18 28.33 2.35 cv (%) 3.85 6.48 3.14 17.33 21.48 12.49 34.31 r2 0.99 0.99 0.99 0.99 0.96 0.95 0.95 getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 39 under the application of ridomil at the rate of 3 kg ha-1 as compared to other genotypes and rates of ridomil application. maximum and minimum mean disease psif, audpc, and rdp were recorded on the genotypes local and arghiti cultivar, respectively, unsprayed and sprayed with the rate of 3 kg ha-1 (table 4). nevertheless, the lowest mean disease psif, audpc, and rdp recorded on arghiti as well as the application of ridomil at the rate of 3 kg ha-1 was statistically at par with ridomil application at the rate of 2 kg ha-1. similar phenomena were observed on the lowest mean disease severity recorded on melkam integrated with the application of ridomil at the rate of 2 and 3 kg ha-1 (table 4). this phenomenon might be the level of the genotype to be withstanding the effect of the disease due to little support obtained from the fungicide application. the effects of integration of sorghum genotypes having different levels of resistance and application of different rates of fungicide had similar results in reducing the development of anthracnose on resistant and moderately resistant genotypes under field conditions (gwary et al., 2008; resende et al., 2009; renata et al., 2012). the high degree of significant difference in audpc values among the evaluated treatments might be due to their genotypic resistance characteristics of the genotypes as well as the different rates of ridomil applications. campbell and madden (1990) reported that the highest audpc values resulted from the highest disease development on plots that remained unmanaged with any management option in combination or alone during the growing periods. similarly, datnoff et al. (2001); resende et al. (2009); renata et al. (2012) reported that the effect of moderately resistant and susceptible sorghum genotypes under different fungicide uses resulted in significantly retarded the development of anthracnose during the growing periods. also, van der plank (1963); campbell and madden (1990); agrios (2005) reported that the highest rdp resulted from the highest disease development on plots that have not managed with any interference of disease management through the integration of crop genotypes, fungicide application, and other options. also, gwary et al. (2008); resende et al. (2009) reported that the resistant and moderately resistant of given genotypes had retarded the rdp when supplemented with a proper fungicide application. table 4: interaction effects of sorghum genotypes and reduce rates of fungicide application on anthracnose incidence and severity at arba minch and derashe in southern ethiopia during 2018 cropping season treatments percent disease incidence at final date (%) percent severity index at final date (%) area under disease progress curve (%day) rate of disease progress (unit day-1) location arba minch 89.93a 55.60a 1029.42a 0.02286a derashe 78.54b 47.13b 928.31b 0.01326b lsd (5%) 1.56 1.95 22.79 0.0017 genotypes + rates of fungicide arghiti + unsprayed 74.58c 31.67f 645.56fg 0.0107ef arghiti + 2 kg ha-1 67.08d 26.38gh 604.72gh 0.0079fg arghiti + 3 kg ha-1 55.83f 22.78h 583.33h 0.0048g melkam + unsprayed 80.42b 40.00e 681.53f 0.0139e melkam + 2 kg ha-1 70.00d 31.39f 630.00f-h 0.0085fg melkam + 3 kg ha-1 62.92e 29.44fg 628.06f-h 0.0071fg seredo + unsprayed 100.00a 76.94b 1338.75bc 0.0335b seredo + 2 kg ha-1 100.00a 67.22c 1237.64d 0.0235cd seredo + 3 kg ha-1 100.00a 62.22d 1143.33e 0.0212d local + unsprayed 100.00a 88.33a 1556.53a 0.0408a local + 2 kg ha-1 100.00a 73.89c 1392.22b 0.0247c local + 3 kg ha-1 100.00a 66.11cd 1304.72c 0.0140d lsd (5%) 3.83 4.79 55.82 0.0042 means in the same column followed by the same letters are not significantly different at 5% level of significant. lsd = least significant difference at p < 0.05 probability level. getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 40 3.3. disease progress curves (dpc) disease progress curves, psi versus dap, drew separately for each sorghum genotype (figure 2). the symptoms have first appeared on seredo and local cultivar at 46 and 42 dap at arba minch and derashe, respectively. the dpc showed that the disease appeared at varying dates depending on the sorghum genotypes and locations. the severity of anthracnose increased over time on unsprayed plots for all sorghum genotypes, implying that the inoculum built up over time. as a general, each curve for all genotypes revealed that disease severity progressed increasingly starting from the beginning to the final severity irrespective of rates of fungicide application, although the sprayed plots have kept progressively lower as compared to the unsprayed plots during the study periods. the dpc for each sorghum genotype also indicated that the disease progression was not similar for each rate of fungicide application. for all sorghum genotypes considered, disease on unsprayed plots showed relatively high progressive curves and exhibited the highest levels of anthracnose severity. thus, severity increased steadily on unsprayed plots of seredo and local cultivar, and reached up to 76.94 and 88.33% at the final date of assessment 114 dat (mean date for the two locations), respectively. anthracnose severity on arghiti and malkam chlorotic specks increased linearly starting from 20% at 44 to (arghiti) and 40% (melkam) 114 dap with lower severity as compared to seredo and local irrespective of rates of fungicide application. for all genotypes and rates of fungicide applications significant variations among the evaluated treatments had started afterward of 72 dap (figure 2). however, on plots sprayed with ridomil at the rate of 3 kg ha-1 disease severity was elevated from 20% (for arghiti and malkam) at 72 dat to 22.78% (for arghiti at 100) and 29.44% (for melkam at 100 dat) and remained consistently very low with 22.78% (arghiti) and 29.44% (melkam) up to final date of an assessment (114 dat). the sorghum genotypes in combination with the application of ridomil at the rate of 2 kg ha-1 followed similar curves with 3 kg ha-1 with slight increments and lied intermediate between unsprayed plots and plots sprayed with ridomil at the rate of 3 kg ha-1 for all sorghum genotypes. similar trends were observed for ridomil at the rate of 2 and 3 kg ha-1 with the genotypes seredo and local cultivars for the assessment dates started from 72 to 114 dap (figure 2). disease progress curves in a combination of sorghum genotypes with ridomil at the rate of 2 and 3 kg ha-1 slowly increased and showed lower levels of severity as compared to the unsprayed plots for all genotypes. integration of sorghum genotypes and rates of fungicide application reduced the disease severity as observed on all managed plots; however, unsprayed plots of all sorghum genotypes eventually reached the highest levels of disease severity. this suggested that the management of anthracnose through a combination of genotypes with different levels of resistance and appropriate rates of fungicide application could provide a safeguard for the crop against the disease during the growing periods. possibly treatment combination could enhance the well-being and vigouristy of the crop that might increase plant chances to endure the pathogen attack and to activate the host defense system through benefits gained from the integrations. in agreement with this study, several researchers reported that a combination of genotypes having different levels of resistance to a given plant disease and supplemented with proper fungicide application could reduce the magnitude of disease severity and enhance the host defense system to withstand the pathogen influence and stabilized towards the end of the epidemic period as compared to the unmanaged ones (campbell and madden, 1990; li et al., 2009; akwero et al., 2016). 3.4. growth and yield related traits evaluation of sorghum genotypes and different rates of ridomil application revealed significant variations in the number of productive plants per plot, thousand seed weight, and grain yield (table 5). the maximum and a minimum number of productive plants per plant, thousand seed weight, and grain yield had recorded at arba minch than derashe. the higher disease severity was recorded at arba minch than derashe, the lower growth and yield parameters recorded at derashe than arba minch (table 5). this phenomenon might be due to the presence of favorable weather conditions for the growth of the crop at arba minch than derash during the growing periods and these might favor the growth and development of the crop at arba minch (table 1). at derash, there was erratic rainfall distribution and high getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 41 figure 2: sorghum anthracnose disease progress curve as affected by different rates of fungicide application on four sorghum genotypes at the study areas in southern ethiopia during the 2018 cropping season. temperature during the growing periods (table 1), and this might disfavor the growth and development of the crop and result in a lower number of productive plants per plant, thousand seed weight, and grain yield than arba minch (table 5). the maximum mean for number of productive plants per plant was found from a combination of seredo with ridomil at the rate of 3 kg ha-1, which was statistically at parity with the values obtained from ridomil at the rate of 2 kg ha-1 for the same genotype. contrarily, the minimum mean for number of productive plants per plant was on an unsprayed plot of local cultivar, which was statistically at parity with the values obtained from ridomil at the rate of 2 kg ha-1 for the same genotype. no statistically significant difference was observed in the number of productive plants per plant for arghiti with both unsprayed and sprayed ones and melkam with sprayed of ridomil at the rate of 2 kg ha-1. this phenomenon might be due to the inherent genetic potential of the genotypes to resist the effect of anthracnose than the different rates of fungicide applications. on the other hand, arghiti and melkam in combination with the application of ridomil at the rate of 2 and 3 kg ha-1 showed the mean highest thousand seed weight as compared to seredo and local cultivar at similar rates of ridomil applications. the lowest mean for thousand seed weight was for unsprayed plots of all genotypes (table 5). arghiti and melkam exhibited the highest grain yield as compared to local cultivar (table 5). this difference might have resulted from the variation in the genetic makeup of the tested genotypes as well as the different rates of ridomil applications. significant variations among sorghum genotypes had observed for growth and yield-related traits and significantly influenced by the genetic makeup of the crop when evaluated for disease management through genotype mixture and fungicide application and gave highest values for these traits over the susceptible genotype and unmanaged plots (thomas et al., 1996; gwary et al., 2003; marley, 2004). similarly, gwary et al. (2008); muhammad et al. (2017); bunker et al. (2019) reported that significant variations among the evaluated sorghum genotypes and fungicide application for the studied parameters. getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 42 table 5: effect of anthracnose on growth and yield-related traits under the integration of sorghum genotypes and reduced rates of fungicide applications at arba minch and derashe in southern ethiopia during the 2018 cropping season treatments number of productive plants per plot, thousand seed weight (g) grain yield (t ha-1) locations arba minch 75.92a 29.26a 3.36a derashe 48.44b 27.40b 1.33b lsd (5%) 5.91 1.84 0.48 genotypes + rates of fungicide arghiti + unsprayed 52.83cd 26.93cd 2.48c arghiti + 2 kg ha-1 70.50b 33.77ab 4.22a arghiti + 3 kg ha-1 70.17b 36.43a 3.78ab melkam + unsprayed 47.00d 24.90de 2.63bc melkam + 2 kg ha-1 69.50b 33.88ab 4.00a melkam + 3 kg ha-1 71.17b 35.52a 3.78ab seredo + unsprayed 63.67bc 21.62e 1.56cd seredo + 2 kg ha-1 87.67ab 27.37cd 2.11c seredo + 3 kg ha-1 94.83a 29.60bc 2.26c local + unsprayed 29.00e 20.70e 0.31e local + 2 kg ha-1 42.67ed 24.13de 0.37de local + 3 kg ha-1 47.17d 25.15c-e 0.67de lsd (5%) 14.48 4.51 2.01 means in the same column followed by the same letters are not significantly different at 5% level of significant. lsd = least significant difference at p < 0.05 probability level. 3.5. association of anthracnose epidemic with the studied crop parameters a significant correlation between and among the mean values of epidemiological and yield-related parameters had observed (table 6). positive and high correlations were observed between final pdi and psi (r = 0.94), audpc (r = 0.92) and dpr (r = 0.0.85). also, positive and high correlations were detected between final psi and audpc (r = 0.99) and dpr (r = 0.96). thus, the result demonstrated that these epidemiological parameters were found interconnected to each other and showed the disease had developed at a faster rate on unsprayed plots than sprayed ones of all sorghum genotypes having different levels of resistance and different rates of fungicide application (table 6). the correlation between epidemiological and crop parameters was negative; however, their significances are varied among the parameters correlated. the association between the number of productive plants per plant and epidemiological parameters was nonsignificant when correlated with each other even though it was negatively associated with them. this phenomenon could be partly related to soil infestation and growth suppression by anthracnose and weather conditions in the studied areas. the results indicated that the observed levels of anthracnose cause a substantial adverse effect on crop parameters considered for all sorghum genotypes (table 6). campbell and madden (1990); thomas et al. (1996); agrios (2005) noted plant diseases had strongly and negatively correlated with growth and yield-related parameters of a given crop. renata et al. (2012) also found a highly and significantly negative association of yield-related parameters of sorghum with anthracnose development. the correlation analysis showed that positive associations had observed between and among the number of productive plants per plant, thousand seed weight, and grain yield. gasura et al. (2015); andekelile and zacharia (2018); seyoum et al. (2019) reported that grain yield had significantly associated with the number of productive plants per plant and thousand seed weight. a linear regression analysis was made to perceive the relationship of disease parameter and grain yield of sorghum to oversee the loss per each treatment under each plot (figure 3). the values of audpc per plot were used to predict grain yield loss in sorghum production. the estimated values of the coefficient between grain yield and audpc was 57.70%. the relationship graph getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 43 table 6: coefficient of correlation between the studied parameters under the integration of sorghum genotypes and reduced rates of fungicide application at the study areas in southern ethiopia during the 2018 cropping season variable final pdi final psi audpc rdp npt tsw final psi 0.94**** audpc 0.92**** 0.99**** dpr 0.85*** 0.96**** 0.93**** npt -0.14ns -0.31ns -0.30ns -0.37ns tsw -0.78** -0.84**** -0.79** -0.86** 0.59* gy -0.82** -0.90**** -0.91**** -84*** 0.56* 0.88*** *, **, *** & **** correlation is significant at p < 0.05, p < 0.001, p < 0.0001 and p < 0.00001, respectively; ns = not significant (p >0.05); pdi = percent disease index; psi = percent severity index; audpc = area under disease progress curve; rdp = rate of disease progress; npt = number of productive tiller; and tsw = thousand seed weight. displayed as the influence of audpc getting higher, the yield obtained from sorghum genotypes becoming lower suggesting that the higher the audpc values, the more susceptible the evaluated sorghum genotypes and the inverse relationship between the disease and grain yield. distances between the line and all the points inferred whether the regression analysis had taken a relationship i.e. strong or weak, the nearer the line is to the points, the stronger the relationship and vice versa. similarly, the regression equation tried to determine in every unit of audpc brought about 0.00299-grain yield losses on the four sorghum genotypes evaluated (figure 3). figure 3: linear regression of grain yield (y) and audpc (x) at the study areas in southern ethiopia during 2018 cropping seasons. 3.6. effects of fungicide rate on economic feasibility of sorghum production relative yield loss assessment the economic feasibility analysis based on the combined effect of the genotypes and fungicide application against anthracnose management had observed (table 7). the nb and mrr were figured out based on pooled data obtained from the two locations per genotype versus ridomil with different spray rates (table 7). the pooled results of the two locations exhibited that integration of ridomil at the rate of 2 kg ha-1 showed the highest net benefit and mrr from arghiti and melkam; however, unsprayed plots of these genotypes were showed the lowest nb and mrr as compared to relatively better-protected plots. seredo required spraying of ridomil at the rate of 3 kg ha-1 to be economically effective in the sorghum production system against anthracnose management. nonetheless, the nb and mrr obtained from local cultivar showed that economically not feasible when it produces through the use of ridomil due to the negative result obtained from the economic analysis (table 7). the high nb and mrr from the above treatment combination could be accredited to high grain yield, and the low nb and mrr had attributed to low grain yield. similar results on the profitability of the use of sorghum genotypes and fungicide applications under integrated management of anthracnose were reported in nigeria by (gwary and asala, 2006b; 2006c). relative yield loss was calculated based on a relatively better ridomil spray rate and the associated grain yield gains or losses in sorghum genotypes (table 7). the relative yield loss that was obtained by the treatment effect was computed based on pooled values of grain yield obtained from the two locations. the highest grain yield losses were recorded on unsprayed plots of all genotypes as compared to the highly protected plots by ridomil at the rate of 2 kg ha-1 for each genotype. the losses in grain yield of sorghum genotypes could be attributed to the severe infection of getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 44 table 7: the economic advantage of using an integration of sorghum genotypes and reduced rates of fungicide application concerning cost-benefit and yield losses at the study areas in southern ethiopia during the 2018 cropping season treatment grain yield (t ha-1) adjusted yield (t ha-1) 10% down total variable cost ($ ha-1) sell revenue ($ ha-1) net benefit ($ ha-1) marginal rate of return (%) relative yield loss (%) sorghum genotypes rates of fungicide arghiti unsprayed 2.48 2.23 312.20 715.47 403.27 0.00 41.23 2 kg ha-1 4.22 3.80 468.71 1217.45 748.74 2.21 0.00 3 kg ha-1 3.78 3.40 489.27 1089.07 599.80 1.11 10.43 melkam unsprayed 2.63 2.36 312.20 757.30 445.10 0.00 34.25 2 kg ha-1 4.00 3.60 468.71 1152.54 683.83 1.53 0.00 3 kg ha-1 3.78 3.40 489.27 1090.52 601.25 0.88 5.50 seredo unsprayed 1.56 1.40 312.20 448.61 136.41 0.00 30.97 2 kg ha-1 2.11 1.90 468.71 608.73 140.02 0.02 6.64 3 kg ha-1 2.26 2.03 489.27 652.00 162.73 0.15 0.00 local unsprayed 0.31 0.28 312.20 89.43 -222.77 0.00 54.41 2 kg ha-1 0.37 0.33 468.71 105.30 -363.41 -0.90 45.59 3 kg ha-1 0.68 0.61 489.27 194.73 -294.54 -0.41 0.00 the mean unit price of sorghum grain yield per ton was 288.50 $ (at the exchange rate of 1$ = 27.73 etb) at the time of selling during the 2018 cropping year. anthracnose at the full-grown stage of the plant, which eventually slew the leaves and reduced the yield obtained from the plants. grain yield losses computed in the present study could not be only attributed to anthracnose as some effects were noted due to turcicum leaf blight (exserohilum turcicum) and viral disease of sorghum including environmental conditions and mechanically damaged due to bird. grain yield losses of 50-100% due to anthracnose had been reported in sorghum production in different parts of the world (thakur and mathur, 2000; tesso et al., 2012). 4. conclusion evaluation of sorghum genotypes and different rates of ridomil exhibited noticeable effects in reducing anthracnose epidemic development and enhance grain yield of sorghum. an economic evaluation of the treatment evaluated revealed that a combination of arghiti and melkam with an application of ridomil at the rate of 2 kg ha-1 provided the highest nb and mrr than unsprayed plots but seredo needed further rates of ridomil to be economically feasible in the management of anthracnose. however, the local cultivar showed unprofitable under sorghum production through the use of fungicide. use of resistant (arghiti) and moderately resistant (melkam) in combination with the application of ridomil at the rate of 2 kg ha-1 have proved to be a relatively better and cost-effective mechanism in reducing anthracnose severity, audpc and rates of disease progression as well increasing production and productivity of sorghum. thus, the use of arghiti and melkam in combination with ridomil at the rate of 2 kg ha-1 could be suggested to producers in the study areas and elsewhere with similar agro-ecology for effective management of anthracnose and sustain production and productivity of sorghum. further studies should be conducted in similar and other agro-ecologies in ethiopia for at least three consecutive years to come up with concrete recommendation on anthracnose management options through a combination of sorghum genotypes and different rates of ridomil, and to enhance sustainable sorghum production in the country. acknowledgment the authors would like to thank southern agricultural research institute (sari) for providing financial support. the authors would like forward special thanks to the staff of the sorghum breeding program at melkasa agricultural research center, ethiopian institute of agricultural research, for their kind contribution to sorghum seeds. the authors are also very grateful to the staff of the crop research work process and the drivers of arba minch agricultural research center for their technical supports during the study periods. the assistance and efforts made by the staff of arba minch crop protection clinic are invaluable and beyond word of expression for us. getachew gudero et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 45 reference adugna, a. 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(2004). the who recommended classification of pesticides by hazard and guidelines to classification. issn: 1684-1042; isbn: 9241546638. geneva, switzerland. 60 pp. 64 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 7 (2), 2020 journal home page: www.ejssd.astu.edu.et astu research paper comparative analysis of inflation dynamics of three african countries: ethiopia, kenya and south africa desa daba fufa  department of statistics, college of computing and informatics, haramaya university, p.o. box138, dire dawa, ethiopia article info abstract article history: received 3 february 2020 received in revised form 22 april 2020 accepted 17 jun 2020 this paper examines a comparative view of the inflation dynamics in three african countries. the study used monthly data from january 2007 to april 2018. to achieve the objectives, the study was deployed varieties of econometric methods. the exploratory analysis reveals that inflation of the sampled countries exhibits similar trends over the long run. the johansson co-integration test result evince that inflation, oil price and exchange rate of ethiopia and south africa had a long run relationship. exchange rates had significant positive effects on inflation dynamics of both countries while world oil price contributes positively in ethiopia but negatively in south africa. in the short run, inflation in kenya was found to be a sign of ethiopia’s inflation. likewise, in south african inflation was an indicator of the inflation in kenya whereas inflation in kenya and ethiopia could not predict inflation would occur in south africa. furthermore, the outcome of the impulse response function demonstrates that exchange rates and oil price shocks affected inflation dynamics of the sampled countries at different stages both directly and indirectly. in the short run, shocks to inflation have an interaction effect across the selected countries. the findings also report that world oil prices are not equally contributes for inflation dynamics in the sampled countries. keywords: co-integration granger causality inflation dynamics impulse response function interaction effect 1. introduction inflation refers to the continuous upsurge in the aggregate level of prices of goods and services in an economy (romer, 2012). it is clearly known that different economies in different parts of the world experience inflation. the severity level may differ from one country to another due to a number of historical country-specific causes. majority of developing countries experienced elevated inflation. even if ethiopia has had a historically low inflation rate compared to other developing countries, in recent time it is experiencing a high inflation rate. high inflation is often linked with lesser growth and financial crises. as al-shammari and al-sabaey (2012) stated, emerging  corresponding author, e-mail: dabadesa6@gmail.com https://doi.org/10.20372/ejssdastu:v7.i2.2020.197 countries are disposed to currency and financial crises more than the industrialized countries. the surge of price is further associated with non-proportional production and consumption of goods and services. this can be due to insufficient investments and steady population growth. high inflation can be a serious problem for many economies worldwide. currently, majority of the african countries like ethiopia, south sudan, zimbabwe, kenya, etc. experienced elevated inflation (durevall and sjö, 2012; gudina et al., 2018; okara and mutuku , 2019). knowing the causes of soaring inflation and it’s the dynamic nature of inflation has always been http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v7.i2.2020.xxxxxx desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 65 a key concern of academics and monitory policymakers around the world. a large body of literature has documented the challenges posed by spiraling inflation on the countries’ economy and factors that contribute to rising inflation dynamics (chou and tseng, 2011; durevall et al., 2012; misati et al., 2013; abounoori et al., 2014; brahmasrene et al., 2014; kargi, 2014; christine et al., 2015; habtamu, 2015; kavila, and le roux, 2016; anh, et al., 2017). these researchers have identified some driving forces of inflation: world food prices, world energy prices such as oil price, domestic food prices, excess money supply, exchange rates, and domestic agricultural supply shocks. durevall and sjö (2012) found that inflation dynamics in ethiopia and kenya were driven by similar factors; of which world food prices and exchange rates had a long-run impact, whereas money growth and agricultural supply shocks had short-to-medium run effects. even though numerous researches have been done, there has been no agreement on the sources of high inflation experienced in recent years and no study scrutinized the interaction effects of inflation dynamics across the countries which are the focus of this study. inflation dynamics across countries may move together due to some common shocks (for instance world oil price shock, demand and supply shocks) and they may have interaction effects on each other if countries have integrated market system, economic and geographical ties (eickmeier and kühnlenz, 2018). economic and trade integration in africa is not a recent phenomenon. particularly, many of the economic and trade integration agreements between ethiopia and kenya were signed at various times, and they have warm trade relations. for example, the 2017 import and export data from the ethiopian revenues and customs authority shows that, ethiopia exported $ 67,717 to kenya and $ 10,532 to south africa. it also imported $ 35,685 and $ 203,974 from kenya and south africa respectively. ethiopia is the only country that shares borders with all the other countries in the horn of africa and is the headquarters of the african union. since the selected countries have strong economic and commercial ties, this research examined the inflation dynamics and interaction effects among ethiopia, kenya and south africa. the study tried to address the following research questions and extends the literatures by considering the research questions: a) to what extent the impacts of the world oil price shock on inflation differ across the selected countries?; b) what are the drivers of domestic inflation dynamics?; and c) is there any factual interaction effects of inflation dynamics across the selected countries? the research was carried out to investigate the trend of inflation, illustrate the granger causal relationship of inflation dynamics and identify the major driving force(s) of high inflation dynamics in three african countries. finally, it suggested the best strategies to manage the variability of inflation for the policy makers and other stakeholders. 2. methods ethiopia, kenya and south africa were purposively selected as the focus of this research, for they strong trade integration and economic ties. kenya and south africa are top trading partners of ethiopia. thus, the researcher considered ethiopia’s, kenya’s and south africa’s inflation dynamics for analysis. for this study, monthly time series data spanning the period from january 2007 to april 2018 concerning ethiopian consumer price index (ethcpi), kenyan consumer price index (kcpi) and south african consumer price index (scpi), exchange rates ((ethiopian birr/usd exchange rate (ethexr), kenyan shilling/ usd exchange rate (kexr) and south african rand/usd exchange rate (sexrt)) and world oil price were collected from national bank of ethiopia and international monitory fund. various parameters such as consumer price index (cpi), wholesale price index (wpi) and sensitive price indicator (spi) were used for measuring inflation. consumer price indexes (cpi) were used as a proxy for inflation. consumer prices are very much linked with the world oil prices because oil products are not only used as a final product but are also used as an input in many of the production processes and economic activities. from 2000 to 2008, world oil prices created new records that severely affected the economy of every country of the world (asghar and naveed, 2015). the study used both descriptive and inferential statistics for data analysis. desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 66 2.1. econometric model specification and tests 2.1.1. tests of stationarity in econometric analysis involving time series data, before any kind of econometric estimation takes place, the collected data should be tested for their stationarity. for this purpose, the augmented dickey-fuller (adf) test and phillip-perron (pp) tests were used to tests for the stationarity. the adf test avoids the problem of dickey-fuller because it corrects for serial correlation; by adding lagged difference terms (gujariti, 2004). the adf test can be represented as: ∆𝑌𝑡 = 𝛾1 + 𝛾2𝑡 + 𝛿𝑌𝑡−1 + ∑ 𝛼𝑖 𝑝 𝑖=1 ∆𝑌𝑡−𝑖 + 𝑡 (1) where, 𝛾1, 𝛾2, 𝛿, and 𝛼 are the coefficients, t is the stochastic trend, 𝑡 is a white noise error term and ∆𝑌𝑡−1=𝑌𝑡−1-𝑌𝑡−2, ∆𝑌𝑡−2=𝑌𝑡−2-𝑌𝑡−3, etc. the test statistic is given below: )ˆ( ˆ   se z t  where, )ˆ(se standard error of ̂ . hypothesis tests: 0: ho where, 1  . to perform the tests, conventional f-test is used but compares the test statistic with the critical f-values developed by dickey and fuller. the phillips-perron test is an alternative method for unit root tests. a pp test ignores any serial correlation in the error term without adding lagged difference terms and they use the standard df or adf test but adjust the t-ratio so that the serial correlation does not affect the asymptotic distribution of the test statistic. 2.1.2. co-integration tests many macroeconomic variables are not stationary at a level but a linear combination of two or more nonstationary series may be stationary and these series are said to be co-integrated. if integrated of order one variables are co-integrated, they are moving together so that there is some long run relationship between them. traditional time-series models have failed to fully capture the behavior of such complex relationship: the johansen's approach takes its initial point in the vector auto regression (var) order p specified by: o 1 1 2 2 ... (2) t t t p t p t y y y y           the above var (p) can be re-specified as: tt p t itt yyy        1 1 1 1o where,    p ij ji p t i andi 11 if the coefficient matrix  has reduced rank r<n, then there exist nxr matrices α and β each with rank r such that  = αβ′ and β’yt is stationary at level. r is the number of co-integrating relationships, the elements of α are known as the adjustment parameters in the vector error correction model and each column of β is a cointegrating vector. it can be shown that for a given r, the maximum likelihood estimator of β defines the combination of yt−1 that yields the r largest canonical correlations of δyt with yt−1 after correcting for lagged differences and deterministic variables when present. johansen proposes two different likelihood ratio tests of the significance of these canonical correlations and thereby the reduced rank of the  matrix: the trace test and maximum eigenvalue test, shown as follows respectively. 1 ˆ (3)ln(1 ) n trace i i r j t       max 1 ˆln(1 ) (4) r j t      where, t is the sample size and i̂ is the i th largest canonical correlation. the trace test tests the null hypothesis of r co-integrating vectors against the alternative hypothesis of n co-integrating vectors. the maximum eigenvalue test, on the other hand, tests the null hypothesis of r co-integrating vectors against the alternative hypothesis of r +1 co-integrating vectors. 2.1.3. lag length selection the lag length for the var (p) model may be determined using model selection criteria. the general approach is to fit var (p) models with orders p = 0, 1, 2…, p max and choose the value of p which minimizes some model selection criteria. the three most common information criteria are the akaike (aic), schwarzbayesian (bic) and hannan-quinn (hq): 2 2 2 2ˆ( ) ln ( ) (5) ln( )ˆ( ) ln ( ) (6) 2 ln lnˆ( ) ln ( ) (7) aic p p pk t t bic p p pk t t hq p p pk t          desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 67 the aic criterion asymptotically overestimates the order with positive probability, whereas the bic and hq criteria estimate the order consistently under fairly general conditions if the true order p is less than or equal to pmax. 2.1.4. vector autoregressive (var) model specification the vector autoregression (var) model is one of the most successful, flexible, and easy to use models for the analysis of multivariate time series. it is a natural extension of the univariate autoregressive model to dynamic multivariate time series. the var model has proven to be especially useful for describing the dynamic behavior of economic and financial time series and for forecasting. it often provides superior forecasts to those from univariate time series models and elaborate theory-based simultaneous equations models. a var model applies when each variable in the system does not only depend on its lags, but also the lags of other variables. the var model has proven to be especially useful for describing the dynamic behavior of economic and financial time series and for forecasting. a multivariate time series yt is a var process of order p or var (p) for short if it follows the mode: o 1 1 2 2 ... , p > 0, t = 1,..., t (8) t t t p t p t y y y y              where, yt is a vector of length k, o  is a k-dimensional vector, φ is a k × k matrix of autoregressive coefficients for j = 1, 2, ……, p. , and { t  } is a sequence of serially uncorrelated random vectors with mean zero and covariance matrix σ. yt is a vector of length k. there are k equations. the coefficient matrix φ measures the dynamic dependence of yt and are unknown and to be estimated from the observed data. 2.1.5. vector error correction model (vecm) the use of vector autoregressive models (var) and vector error correction models (vecm) for analyzing dynamic relationships among financial variables has become common in the literature. from the above var (p) model specification, we can rewrite as a vecm. ∆y t =ϑ+ π𝑦𝑡−1+ ∑ γ𝑖 𝑝−1 𝑖=1 ∆𝒚𝑡−𝑖 + 𝜺𝑡 (9) where, π𝑖 = αβ′,γ𝑖 = − ∑  𝑗 𝑝 𝑗=𝑖+1 and 𝐼𝑛is an identity matrix. π and the short-run parameter γ𝑖 i=1, 2,…, p-1 are p × p matrices of coefficients. the vecm expressed above is convenient because the hypothesis of cointegration can be stated in terms of the long-run impact matrix, π. 2.1.7. granger analysis this study uses engle-granger causality test to analyze the relationship between the selected variables. let xt and yt be two stationary (after possible transformations) time series of length t. a variable xt is said to granger causes another variable yt, if yt can be better predicted from the past of xt and yt together than the past of yt alone, other relevant information being used in the prediction (pierce, 1977). likewise the researcher was interested to see the grander causality of inflation dynamics between the selected countries and other selected variables. 2.1.8. impulse response function the var model can be used for structural inference and policy analysis. in structural analysis, certain assumptions about the causal structure of the data under investigation are imposed, and the resulting causal impacts of unexpected shocks or innovations to specified variables on the variables in the model are summarized. granger-causality may not tell us the complete story about the interactions between the variables of a system. in applied work, it is often of interest to know the response of one variable to an impulse in another variable in a system that involves a number of further variables as well. these causal impacts are usually summarized with impulse response functions and forecast error variance decompositions. identification of the underlying structural shocks is necessary if we are to estimate the effects of an exogenous shock to a single variable on the dynamic paths of all of the variables of the system, which we call impulse-response functions (irfs). the impulse response function can be plotted as the period multipliers against the lag length. an impulse response function traces the response of a variable of interest to an exogenous shock. often the response is portrayed graphically, with horizon on the horizontal axis and response on the vertical axis. it traces the effect of a one standard deviation shock to one of the innovations on current and future values of the endogenous variables. a shock to the i th variable directly affects the j th variable, desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 68 and may also transmit to all of the endogenous variables through the dynamic structure of the var. any covariance stationary var (p) process has a wald representation of the form: the impulse response function (irf) of a dynamic system is its output when presented with a brief input signal, called an impulse. more generally, an impulse response refers to the reaction of any dynamic system in response to some external change. a var was written in vector ma (∞) form as: 1 1 2 2 ... (10) t t t t y              thus, the matrix s  has the interpretation s t st y       ' that is, the row i, column j element of s  identifies the consequences of one unit increase in the j th variable’s innovation at date t ( jt ) for the value of the i th variable at time t+s( sit y  ), holding all other innovations at all dates constant. ti sti y '   as a function of s is called the impulse response function. it describes the response of sit y  a one-time impulse in tj y with all other variables dated t or earlier held constant. 3. results and discussions 3.1. descriptive analysis figure 1 depicts the consumer price index (inflation) of the selected countries and world oil price. the graphical plot of the three variables (cpi) shows an upward increasing trend in which the co-movement showed greater similarity starting from the beginning onwards. this graphical plot confirms the finding of durevall and sjö (2012). they found that inflation in both ethiopia and kenya has increasing patterns. the world oil price is more fluctuated over the given period than inflation. the price increased to higher values in 2008 and it does not show a clear trend which contrasts the finding of ademe (2015). domestic inflation of ethiopia had a similar trend with that of world oil price. the fluctuation in oil prices led to the fluctuation of inflation. the oil prices which were higher will be immediately followed by the rising prices of oil products including gasoline and fuel oil, which were used by the consumer. the exchange rate of the three countries, generally, showed an increasing trend with high fluctuation (figure 2). the fluctuation is low in the case of ethiopia compared to the other countries. this low fluctuation may be due to the fact that ethiopian exchange rate is characterized by a managed floating regime. figure 1: graphical representation of inflation time in month c p i( e th io p ia ) 2008 2012 2016 2 0 4 0 6 0 8 0 1 2 0 time in month c p i( k e n y a ) 2008 2012 2016 8 0 1 2 0 1 6 0 time in month c p i( s o u th a fr ic a ) 2008 2012 2016 6 0 8 0 1 0 0 time in month p ri c e o f o il 2008 2012 2016 4 0 8 0 1 2 0 time in month c p i( e th io p ia ) 2008 2012 2016 2 0 4 0 6 0 8 0 1 2 0 time in month c p i( k e n y a ) 2008 2012 2016 8 0 1 2 0 1 6 0 time in month c p i( s o u th a fr ic a ) 2008 2012 2016 6 0 8 0 1 0 0 time in month p ri c e o f o il 2008 2012 2016 4 0 8 0 1 2 0 desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 69 3.2. tests of stationarity augmented dickey-fuller (adf) and philips perron (pp) tests were used to test the stationarity properties of the series. the summary of the result is given in table 1a) and b). the result indicates that the null hypothesis of the presence of unit root has failed to reject at 5 percent level of significances. this implies that the series is not stationary at level. on the other hand, all the variables at 5 the percent level of significance are statistically significant in the first difference. we thus realize that all the series over time is stationary in first difference. table 1a): adf tests of stationary at a level at the first difference variables test statistic critical value at 5% p-values test statistic critical value at 5% p-values oil price -1.631 -2.888 0.4669 -5.279 -2.888 0.000 ethexr 0.690 -2.888 0.9896 -7.814 -2.888 0.000 ethcpi 0.906 -2.888 0.9932 -5.772 -2.888 0.000 kexr -1.419 -2.888 0.5732 -8.412 -2.888 0.000 kcpi 0.221 -2.888 0.9734 -6.425 -2.888 0.000 sexr -0.527 -2.888 0.8867 -6.421 -2.888 0.000 scpi 0.361 -2.888 0.9800 -8.068 -2.888 0.000 source: own computation results on sample data table 1b): pp tests of stationarity variables at a level at first difference test statistic critical value at 5% p-values test statistic critical value at 5% pvalues oil price -1.878 -2.888 0.3424 -7.480 -2.888 0.000 ethexr 0.546 -2.888 0.9862 -9.108 -2.888 0.000 ethcpi 0.714 -2.888 0.9901 -7.808 -2.888 0.000 kexr -1.138 -2.888 0.6997 -8.559 -2.888 0.000 kcpi -2.491 -2.888 0.1176 -10.901 -2.888 0.000 sexr -1.225 -2.888 0.6629 -21.732 -2.888 0.000 scpi 0.707 -2.888 0.9900 -8.405 -2.888 0.000 source: own computation results on sample data figure 2: exchange rate of the selected countries desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 70 3.3. optimal lags determination table 2 reports optimal lags order selection statistics. in this table the minimum values from each of the information criteria are given by star sign (*).the result shows the optimal lag length is one. so, we precede further tests and estimations with lag (1). hence, the var (p) and vecm (p) models which are used are var (1) and vecm (1). 3.4. co-integration analysis having confirmed the existence of unit root at a level in the series in table 1, co-integration tests were conducted by johansson test of co-integration. table 3 reports the co-integration analysis outputs. the result shows that the trace test didn’t reject the null hypothesis of zero co-integrating vector at 5% level of significance (22.2364*) in kenya in favor of at most one cointegrating vectors in case of ethiopia and south africa (13.8785* and 11.7716*) respectively. therefore, the computed trace statistics that are greater than the critical trace values at a 5 percent level of significance explains the rejection of the null hypothesis of zero cointegrating vectors. this implies that inflation in the case of ethiopia and south africa has a long run relationship with respective to their exchange rate and world oil prices. 3.5. estimation of the vector autoregressive (var) model table 4 comprises the result of inflation dynamics computed by using var model. the computed values indicate that the past value of the endogenous variable information in ethiopia is positive significant effect in determining its own current values (33.76%) at five percent significant levels. from the results, it is also clearly inferred that the past values of inflation in kenya (93.74%) and other constant variables (35.42%) have significant effect in determining the current values of inflation in ethiopia keeping other variables constant. for the equation of inflation in kenya, the past values of kcpi and scpi have positive significant effect on the current values of kcpi at five significant levels. 3.6. vector error correction model estimation the presence of co-integration suggests a long run relationship among the variables under consideration. to discuss the long run equilibrium relations and shortrun adjustment processes, the researcher estimated vector error correction model. the long run relationship and short-run adjustment processes among inflation, exchange rates and world oil price for 1 co-integrating vector for ethiopia are shown in table 5. the coefficients of exchange rate and world oil price at the first lag were significant at 5% level of significance. from the table, it is inferred that there was no long-run causality between inflation and its first lag. when we consider the first equation (inflation) the coefficient error correction term values are non-negative and not significant. the values do not confirming long run causality. the coefficient of error correction term of exchange rate equation and world oil prices equation values are negative and significant at 5%. the coefficient values are -22.58 and -27.08 percent monthly, meaning that the system corrects the previous period disequilibrium at a speed of 22.58 and 27.08, respectively. the error correction term which is the normalized co-integrating equation obtained from the vec model is as follows: table 2: optimal lags determination source: own computation results on sample data lag ll lr df p fpe aic hqic sbic 0 -1555.630 55.835 23.888 23.950 24.041* 1 -1471.540 172.190 49 0.000 31.726* 23.321 23.821* 24.550 2 -1424.500 94.079 49 0.000 32.886 23.351 24.288 25.656 3 -1377.370 94.258 49 0.000 34.365 23.380 24.753 26.760 4 -1341.740 71.262* 49 0.021 43.416 23.584 25.394 28.039 δethcpi = -45808 δethexr + 0.3035 δworld oil price – 144395 desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 71 table 3: johansson co-integration tests johanson co-integration tests in case of ethiopia (ethcpi,ethexr and world oil price) maximum trace 5% critical rank parms ll eigenvalue statistic value 0 3 -671.7423 . 38.8071 29.68 1 7 -659.278 0.0589 13.8785* 15.41 2 11 -653.23229 0.0582 1.7871 3.76 3 12 -652.33874 0.01315 johansson co-integration tests in case of kenya (kcpi,kert and world oil price) maximum trace 5% critical rank parms ll eigenvalue statistic value 0 3 -855.7808 22.2364* 29.68 1 7 -848.1779 0.1073 7.0305 15.41 2 11 -844.6693 0.0510 0.0132 3.76 3 12 -844.6693 0.0001 johansson co-integration tests in case of south africa (scpi, sexr and world oil price) maximum trace 5% critical rank parms ll eigenvalue statistic value 0 3 -551.944 . 39.0134 29.68 1 7 -538.323 0.184 11.7716* 15.41 2 11 -532.444 0.084 0.0124 3.76 3 12 -532.438 0.000 johansson co-integration tests of inflation across the sampled countries maximum trace 5% critical rank parms ll eigenvalue statistic value 0 3 -412.5450 . 19.7748* 29.68 1 7 -405.3309 0.10136 5.3466 15.41 2 11 -403.4722 0.0272 1.6291 3.76 3 12 -402.6576 0.0120 source: own computation results on sample data table 4: output of var model for inflation of the sampled countries coef. std. err. z p>z [95% conf. interval] d_ethcpi ethcpild kcpi-ld. scpild. cons 0.3376 0.9374 0.0780 0.3542 0.0844 0.0387 0.2615 0.1384 4.00 24.17 0.30 2.56 0.000 0.000 0.766 0.011 0.1722 0.8614 -0.4345 0.0829 0. 5030 1.0134 0.5904 0.6256 d_kcpi ethcpi -ld kcpi-ld. scpi-ld. cons -0.0130 0.4880 0.5851 0.2210 0.0719 0 .0731 0.2228 0.1180 -0.18 6.68 2.63 1.87 0.857 0.000 0.009 0.061 -0.1539 0. 3138 0.1483 -0.0101 0.1279 0.6312 1.0219 0.4523 d_scpi ethcpi-ld. kcpi-ld. scpi-ld. cons 0.0311 0.0268 0.2681 0.2615 0.0280 0.0285 0.0870 0.0460 1.11 0.94 3.08 5.68 0.268 0.347 0.002 0.000 -0.0239 -0.0290 0.0976 0.1712 0.0861 0.0827 0.4387 0.3518 source: own computation results on sample data desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 72 according to normalized equation, exchange rate and world oil price contributes to inflation in the longrun. table a-2 (appendix) reports the vec output of inflation in south africa. the result shows that the coefficients of error correction terms are significant at 5% significant level. as understood from the vecm model results, exchange rate contributed negatively in the long run to the inflation in ethiopia and south africa. that is, contribute negatively to decrease the exchange rate aggravated inflation of the mentioned country. conversely, world oil price contributes to inflation positively in the long run in case of ethiopia and but negatively to that of south africa. the increase in oil prices led to rising inflation and vice versa, which contrasts the finding of sek et al. (2015). the study found that oil prices have a considerable effect on domestic prices in developing countries which are highly oil dependent. 3.7. granger causality tests recall that even though a co-integration test shows long run relationship among variables, it does not specify the direction of a causal relation. chi-square statistics and probability values constructed under the null hypothesis is rejected if the probability value is more than 5% significance level. table 6 provides the var & vec granger causality tests results. vecgranger causality analyses of inflation, exchange rate, and world oil price in case of ethiopia provides the existence of unidirectional causality running from the world oil price to inflation at the 5% significance level (0.0021). moreover, there is unidirectional causality running from the joint exchange rate and world oil price to inflation. this evinces that past values of joint world oil price and exchange rate enabled to predict the present values of inflation. in the case of south africa, the vec granger causality/block exogeneity wald tests indicate the existence of unidirectional causality running from world oil price to inflation at 5% of significance level. these results are in agreement with the finding of brahmasrene et al., (2014). they documented that any changes in international oil price will cause a change in inflation. similarly, the var granger causality wald tests results regarding inflation in the sampled countries show the unidirectional granger causality running from inflation in southern africa to inflation in kenya. this implies that in the short run inflation in south africa is one of the driving forces of inflation in kenya in addition to other macro-economic variables. in addition, unidirectional granger causality running from inflation in kenya to ethiopia was observed. world oil price has no equal contribution for the inflation fluctuation across the selected countries. table 5: output of vecm in case of ethiopia coef. std. err. z p>z [95% conf. interval] d_ethcpi ce1_1 0.0071 0.0100 0.72 0.474 -0.0124 0.0267 cons 0.7240 0.0871 8.32 0.000 0.5531 0.8946 d_ethexr ce1_2 -0.2258 0.0881 -2.56 0.010 -0.0532 -0.3984 cons 0.1376 0.028713 4.79 0.000 0.0813 0.1938 d_oil price cel_3. -0.2708 0.0602 -4.50 0.000 -0.3888 -0.1528 cons 0.0181 0.5259 0.03 0.973 -1.0128 1.0490 johansen normalization restriction imposed beta coef std. err. z p>|z| [95% conf. interval] ethcpi 1 ethexr -4.5808 0.3470 -13.20 0.000 -5.2609 -3.9007 oil price 0.3035 0.0685 4.43 0.000 0.1692 0.4377 cons -14.4395 source: own computation results on sample data desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 73 table 6: var &vec granger causality tests results vec granger causality/block exogeneity wald tests in case of ethiopia equation excluded chi2 df prob>chi2 d.ethcpi d.ethexr 0.1940 1 0.6596 d.oil price 9.4180 1 0.0021 all 9.5626 2 0.0084 d.ethexr d. ethcpi 0.0230 1 0.8796 d.oil price. 0.1560 1 0.6929 all 0.2653 2 0.8758 d.oil price d.ethexr 0.1195 1 0.7295 d. ethcpi 0.1769 1 0.6741 all 0.3105 2 0.8562 vec granger causality/block exogeneity wald tests in case of south africa equation excluded chi2 df prob>chi2 d. scpi d. sexr 2.5478 1 0.1104 d.oil price 8.648 1 0.0033 all 11.7925 2 0.0027 d. sexr d. scpi 0.9112 1 0.3398 d.oil price. 8.0359 1 0.0046 all 10.7764 2 0.0046 d. oil price d. scpi 0.8433 1 0.3585 d. sexr 0.0492 1 0.8244 all 1.0237 2 0.5994 var granger causality/block exogeneity wald tests in case of kenya equation excluded chi2 df prob>chi2 d. kcpi d. kexr 2.3925 1 0.1219 d.oil price 3.2667 1 0.0707 all 4.0564 2 0.1317 d. kexr d. kcpi 3.6663 1 0.0555 d.oil price. 0.2595 1 0.6105 all 4.7924 2 0.0911 d. oil price d. kcpi 0.3027 1 0.5822 d. kexr 1.3963 1 0.2373 all 3.8442 2 0.1463 var granger causality/block exogeneity wald tests of inflation in case of selected countries equation excluded chi2 df prob>chi2 d. ethcpi d. kcpi 6.1847 1 0.0194 d. scpi 0.0889 1 0.7660 all 2.0275 2 0.3630 d. kcpi d. ethcpi .03252 1 0.8570 d. scpi. 6.8917 1 0.0090 all 7.2409 2 0.0270 d. scpi d. ethcpi 1.2269 1 0.2680 d. kcpi 0.8835 1 0.3470 all 3.8442 2 0.1463 source: own computation results on sample data 3.8. impulse response function an impulse response function traces the effect of a one-time shock to one of the innovations on current and future values of the endogenous variables. figure 3 displays the estimated impulse response of inflation in ethiopia toward the change of world oil price and ethiopian birr/usa dollar exchange rate. the figure reveals that inflation responds positively over the whole period with slightly increasing when a positive shock given to an exchange rate, which supports the finding of habtamu getnet (2015). he has found that the exchange rate has a direct effect on the increments or decrements desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 74 of domestic inflation of ethiopia. figure 4 reports the estimated var impulse response function of inflation across the sampled countries. the result shows a one standard error shock of ethiopian inflation positively influenced kenyan’s inflation, but a positive shock of the inflation in kenya affected the inflation in ethiopia negatively. from this, it is evident that when there is positive shock to ethiopia’s inflation, inflation in kenya is increasing. nevertheless, the inflation in ethiopia decreases if kenya’s inflation gets a shock. it also understood that a greater real trade integration and border ties could increase the sensitivity of inflation to cross border shocks. figure a-1 (annex) shows that the impulse response function of inflation dynamics in kenyan to shilling/ usa dollar exchange rate and world oil price. the figure reveals that the response of inflation to a unit standard deviation shock to exchange rate is positive and almost with increasing movements which contrasts the finding of okara and mutuku (2019). they found that a shock given to exchange rate has negative effects on inflation. also, the response of inflation to a unit standard deviation shock to world oil price is positive. in other words, when there is a positive innovation given to exchange rate and oil price increases the inflation in that country. figure a-2 (annex) exhibits impulse response function of inflation in south africa towards rand/usa dollar exchange rate and world oil price received. the plot shows that the response of inflation in south africa was positive when exchange rate faced a shock. exchange rate shocks had a similar positive effect on inflation in both ethiopia and kenya, yet negative in south africa. the response of inflation towards the world oil price is similar in all selected countries over the given time horizon. furthermore, the response of inflation for itself innovation has little effect for the selected countries. 0.0 0.4 0.8 1.2 1.6 1 2 3 4 5 6 7 8 9 10 response of ethcpi to ethcpi 0.0 0.4 0.8 1.2 1.6 1 2 3 4 5 6 7 8 9 10 response of ethcpi to ethexr 0.0 0.4 0.8 1.2 1.6 1 2 3 4 5 6 7 8 9 10 response of ethcpi to oil .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 response of ethexr to ethcpi .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 response of ethexr to ethexr .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 response of ethexr to oil -4 -2 0 2 4 6 8 1 2 3 4 5 6 7 8 9 10 response of oil to ethcpi -4 -2 0 2 4 6 8 1 2 3 4 5 6 7 8 9 10 response of oil to ethexr -4 -2 0 2 4 6 8 1 2 3 4 5 6 7 8 9 10 response of oil to oil response to nonfactorized one s.d. innovations figure 3: impulse response functions of inflation in case of ethiopia desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 75 -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 response of ethcpi to ethcpi -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 response of ethcpi to kcpi -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 response of ethcpi to scpi -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 response of kcpi to ethcpi -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 response of kcpi to kcpi -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 response of kcpi to scpi -.2 -.1 .0 .1 .2 .3 .4 1 2 3 4 5 6 7 8 9 10 response of scpi to ethcpi -.2 -.1 .0 .1 .2 .3 .4 1 2 3 4 5 6 7 8 9 10 response of scpi to kcpi -.2 -.1 .0 .1 .2 .3 .4 1 2 3 4 5 6 7 8 9 10 response of scpi to scpi response to cholesky one s.d. innovations ± 2 s.e. figure 4: var impulse response function of inflation across the selected countries 4. conclusions this study empirically presents the comparative view of inflation dynamics among three african countries. even though the main driving forces of high inflation across the sampled countries varies, the exploratory analysis of monthly data spanning from january 2007 to april 2018 shows the inflation trend is similar in the long run. the result of johansen cointegration test revealed that the cpi, exchange rates and oil price have co-integration relationship in ethiopia and south africa case. in the long run, inflation in both countries is driven by exchange rates and world oil price. exchange rates have positively significant effects on inflation dynamics of both countries while world oil price contributes positively in ethiopia but negatively in south africa. in the short run, inflation in kenya has a predicting power about inflation in ethiopia and inflation in south africa has a predicting power about inflation in kenya. on the other hand, inflation in kenya and ethiopia do not have a predicting power about inflation in south africa. furthermore, the outcome of impulse response function demonstrates that exchange rates and oil price shocks affects inflation dynamics of the sampled countries at different stages both directly as well as indirectly. shocks to inflation in south africa have positive impact on inflation in ethiopia while shocks to inflation in kenya have negative in the short run. inflation across the sampled countries has no long run interactive relationship. there are numerous policy implications that can be drawn from this analysis. first, there is growing evidence that exchange rates are a driving force for high inflation for the selected countries. so, establishment of monitory union is recommended to stabilize this high inflation variability by managing exchange rate variability. second, fluctuation of oil price is also observed as it is a driving force of high inflation. low income countries like ethiopia and kenya are unlikely to have the resources to have stocks to take advantage of periods of low prices or insurance against rises, so that they will be affected by price increases. therefore, desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 76 it is a mandatory for the interference of central bank to stabilize the high variability of oil price by taking into account those countries. finally, increased economic and trade integrity is likely to lead greater sensitivity of aggregate inflation dynamics to costs of imported inputs, especially when cost changes are large in magnitude. this issue should be a concern of macroeconomic policies coordination because no single country can on its own assure stability to the international economic system. annex: table a-1: the output of var (1) in the case of kenya coef. std. err. z p>z [95% conf. interval] d_kcpi kcpi |ld. 0.5255 0.0720 7.30 0.000 0.3830 0.6679 kexr |ld. 0.0241 0.0384 0.63 0.532 -0.0518 0.1000 oil |ld. 0.0187 0.0112 1.67 0.097 -0.0035 0.0410 _cons 0.4136 0.0921 4.49 0.000 0.2314 0.5958 d_kexr kcpi|ld. 0.0983 0.1610 0.61 0.542 -0.2201 0.4168 kexr |ld. 0.2721 0.0858 3.17 0.002 0.1024 0.4418 oil |ld. -0.0237 0.0251 -0.94 0.348 -0.0733 0.0260 _cons 0.0885 0.2059 0.43 0.668 -0.3188 0.4958 d_oil kcpi | ld. -0.3095 0.5272 -0.59 0.558 -1.3526 0.7336 kexr |ld. -0.4966 0.2809 -1.77 0.079 -1.0524 0.0592 oil | ld. 0.3541 0.0822 4.31 0.000 0.1915 0.5167 _cons 0.4250 0.6743 0.63 0.530 -0.9090 1.7589 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 1 2 3 4 5 6 7 8 9 10 response of kexr to kexr -0.5 0.0 0.5 1.0 1.5 2.0 2.5 1 2 3 4 5 6 7 8 9 10 response of kexr to kcpi -0.5 0.0 0.5 1.0 1.5 2.0 2.5 1 2 3 4 5 6 7 8 9 10 response of kexr to oil -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 response of kcpi to kexr -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 response of kcpi to kcpi -0.4 0.0 0.4 0.8 1.2 1 2 3 4 5 6 7 8 9 10 response of kcpi to oil -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 response of oil to kexr -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 response of oil to kcpi -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 response of oil to oil response to cholesky one s.d. innovations ± 2 s.e. figure a-1: impulse response function of inflation dynamics in case of kenya appendix desa daba. ethiop.j.sci.sustain.dev., vol. 7 (2), 2020 77 table a-2: output of vecm in case of south africa coef. std. err. z p>z [95% conf. interval] d_scpi _ce1 |l1 -0.0063 0.0022 -2.84 0.004 -0.0107 -0.0020 _cons 0.4164 0.0280 14.89 0.000 0.3616 0.4713 d_sexr _ce1 |l1 0.1087 0.0048 2.27 0.023 0.0015 0.0203 _cons 0.0354 0.0601 0.59 0.556 -0.0824 0.1532 d_oil _ce1 | l1. 0.1638 0.0427 3.83 0.000 0.0800 0.2475 _cons 0.0138 0.5359 0.03 0.979 -1.0365 1.0641 johansen normalization restriction imposed beta coef std. err. z p>|z| [95% conf. interval] _scpi 1 sexr -10.826 0.9508 -11.39 0.000 -12.6899 -8.9630 oil -0.5498 0.0980 -5.61 0.000 -0.7418 -0.3577 _cons 64.1050 source: own computation results on sample data -.1 .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 response of scpi to scpi -.1 .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 response of scpi to sexr -.1 .0 .1 .2 .3 .4 .5 1 2 3 4 5 6 7 8 9 10 response of scpi to oil -.2 .0 .2 .4 .6 1 2 3 4 5 6 7 8 9 10 response of sexr to scpi -.2 .0 .2 .4 .6 1 2 3 4 5 6 7 8 9 10 response of sexr to sexr -.2 .0 .2 .4 .6 1 2 3 4 5 6 7 8 9 10 response of sexr to oil -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 response of oil to scpi -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 response of oil to sexr -8 -4 0 4 8 1 2 3 4 5 6 7 8 9 10 response of oil to oil response to cholesky one s.d. innovations figure a-2: impulse response function of inflation in case of south africa reference abounoori, a.a., nazarian, r. & 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(2015). a comparative study on the effects of oil price changes on inflation. procedia economics and finance, 26: 630-636. 96 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 8 (2), 2021 journal home page: www.ejssd.astu.edu.et astu research paper medicinal plant part identification and classification using deep learning based on multi label categories misganaw aguate1,, abebe tesfahun2, amlakie aschale1 1department of electrical and computer engineering, debre tabor university, p. o. box 272, debre tabor, ethiopia 2school of electrical and computer engineering, debre markos university, p. o. box 269, debre markos, ethiopia article info abstract article history: received 11 may 2021 received in revised form 02 august 2020 accepted 20 august 2021 plants have been used as direct medicinal sources since ancient times as well as today. however, researchers and pharmacists are facing difficulties to identify medicinal plant parts before starting ingredient extraction in the laboratory. this study was conducted to identify the medicinal plant part based on multi-label categories by employing a sigmoid classifier as the last layer of convolutional neural network (cnn). the study employed supervised learning approach in which the true values were predefined initially for the classifier using data annotation phase. hence, leaf images of the plants were taken as an identity for the rest of the plant parts. the system was designed based on transfer learning by adopting (fine tune) the pretrained models that employ cnn and trained using image net. high-resolution cameras for data acquisition and google colab for the experiment (training and testing) were used. mobile net performed best with an accuracy of 93% for training sets and 92% for testing sets. when the models were evaluated using f1_score, it performed 94%. without batch normalization at fully connected layer, this model scored 84%. so, mobile net obtained higher performance, and suitable to classify the medicinal plant body part. it was also taken as the fastest model to train because mobile net used depth wise separable convolution method that reduces scalar multiplication through convolution. by observing the results obtained from the presence and absence of batch normalization, this study deduced that batch normalization is advantageous to obtain good classification performances of the models. keywords: medicinal plant parts deep learning multi-label convolutional neural network fine-tuned model 1. introduction extensive research on medicinal plants identification has been done by various researchers (dileep et al., 2019, bandara, et al. 2019, tan et al., 2020; etc.). however, the studies did not answer the questions like which part of the plants is used as a medicine. accordingly, this study tried to identify the specific parts of medicinal plants. the identification of the medicinal plant parts can be done using image processing and chemical ingredient extraction. but using its chemical ingredient consumes time and needs high expenditure for laboratory  corresponding author, e-mail: ethiomisgie@gmail.com https://doi.org/10.20372/ejssdastu:v8.i2.2021.380 equipment. so, to reduce this problem image processing is the preferred approach. this approach can be handled with the help of deep learning. it is obvious that, deep learning can be used in speech recognition, natural language processing, machine translations, audio recognitions, bioinformatics, drug design, medical image identifications, and medicinal plant identification and classification (amuthalingeswaran et al., 2019). that excited us to apply image processing with deep learning. this study used a multi-label classification technique to http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v8.i2.2021........... misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 97 improve indigenous knowledge using transfer learning. mobile net, vgg16, and inception_v3 are among the adopted deep learning techniques. the ability of plants to cure disease using its parts and the need of improvement of indigenous knowledge to modern medical science are the main points for the excitation to precede this study. the digitization of useful species of plants and their information is necessary. several researchers have tried to develop a more robust and efficient plant recognition system by exploiting pattern recognition and image processing techniques based on plant leaves, flowers, barks, and fruits. however, leaves play a very important role among all the other parts of a plant as they contains rich information as well as more reliability (naresh et al., 2016). hence, this study used the leaves of medicinal plants to extract unique features. proving of overfitting is not only affected by the depth of convolutional layers and the number of datasets, addition of batch normalization at the fully connected layer of cnn to makes the model to learn fast and obtain good classification performances and taking of the leaf images from its back side to makes the cnn to extract feature of the leaves uniquely and accurately are the major contribution of this study. in 2019, the extraction of shape, color and texture features from leaf images was employed and to train the artificial neural network (ann) to identify the exact leaf classes (r.janani, 2013). the plant species can be identified based on the input leaf sample (sivaranjani et al., 2019). the medicinal plant data set was developed based on the extraction of texture and color features from plant leaf images (pacifico et al., 2019). the author used machine learning for recognition of medicinal plants. but using deep learning is good to classify medicinal plant due to its ability to extract features automatically. herbal species can also be identified using their flower images (bandara et al., 2019). the authors have used svm, decision trees and k-nn. using only leaf features of shape, color, texture is not a distinct attribute of leaves. in lee et al. (2017), the authors proved that vein and contour features are good to uniquely identify plant species. raw plant leaf image is represented into deep features using knowledge transfer from object identification to plant species identification (prasad et al., 2017). vgg-16 convnet architecture is used to train and classify with combination of pca which can reduce feature vector to optimize classification cost (prasad et al., 2017). in (tan et al. 2020) the leaf images were preprocessed and the features were extracted by pre-trained alexnet, finetuned alexnet and d-leaf. these features were then classified by support vector machine (svm), artificial neural network (ann), k-nearest neighbour (knn), naïvebayes (nb) and cnn. ayurleaf which is a deep learning based cnn model proposed in (dileep et al., 2019) to classify medicinal plants. 2. methods and materials this study used cnn which is the backbone of deep learning algorithm and can automatically extract multiple unique features of plant leaves. the study also employed transfer learning technique by adding batch normalization at the fully connected layer of cnn, and tune weights and training hyper parameters. in this study, we took the backside of leaves to make the model extract the features uniquely and identify medicinal plant parts accurately. 2.1. proposed system architecture in this research six procedures were followed such as data collection, data annotation (labelling), image preprocessing, feature extraction and training, testing (model evaluation) and finally classification of medicinal plant parts. figure 1 shows the high-level system architecture of the study. the input image phase includes data acquisition and annotation (data labelling). model building phase includes feature extraction and training tasks. the detail description is mentioned in the following consecutive sections. 2.2. data acquisition the data was collected using a high-resolution camera (techno spark k7 with 13mp and samsung a30s with 25mp). these sample data weree taken from gojjam, jimma, and kefa. these data collection procedure took two months. when taking images of the plant leaves, to avoid data augmentation, the different light intensity strength and direction of leaf positions were considered. backsides of the leaves were captured to extract vein feature accurately. we mde the focal length different depending on the broadness of leaves to make the prediction consistent. the dataset contains 15,100 medicinal plant leaf images. each plant has an equal number of leaf images (300 images) but the number of plants categorized in each misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 98 figure 1: high level system architecture label is different. hence, the study has imbalanced data in each category. the following guidelines are taken for this data acquisition:  medium aged and young parts of the plant leaf are selected;  the focal length of the camera (distance between leaves and camera) is taken depending on the broadness and narrowness of the plant leaves;  the white background of the image was selected to avoid confusion and get a clear leaf image structure;  dried and diseased leaves excluded to make the prediction consistent, and  the leaf images are captured immediately after cut out from the plants to reduce the loss of leaf features.  the camera stands perpendicular to the leaf stand (i.e. the position taken 90° from the leaf stand). 2.3. visualizing intensity variation of the data the frequency of pixels in rgb channels, brightness and, darkness of the images can be visualized by simply observing the vertical, left, and the right parts of the image histogram. hence, figure 2 shows images of one leaf but in different pixel intensity sample and figure 3 and 4 (histogram plot) describe how it varies based on its three-channel pixel intensity and distribution throughout the different images. figure 3 shows the histogram of sample one (s1) image. it is different from sample three (s3). the leaf s1 and s3 are the same but this variation is due to light intensity while the images are captured. this variation of the datasets in a single leaf makes the model to classify consistently while it faces different images captured by different cameras and environments. figure 2: intensity variation of single leaf image figure 3: histogram of leaf image (s1) misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 99 figure 4: histogram of leaf image (s3) 2.4. data annotation the labeling tasks were supported by five experts with 5, 10, 13, 28and 30-year experiences who are currently working on traditional medicine preparation. initially, 72 plants were selected. but finally, 52 were taken as the complete dataset. twenty plants were avoided because there are not commonly labeled parts by the experts for those plants. since the system is based on supervised learning approach, all parts of the plats were tagged (mapped) on the leaves image as indicated in table 1, img_1, img_2…. img_n indicates the name of the leaf images file. table 1: sample of data annotation (labeling) 2.5. pre-processing to reduce computational time during training, the input image was resized to 128 x 128. in the system architecture, normalization means scaling of image pixels. image pixels are integer values from 1 up to 255. in cnn, processing a large integer value can disrupt or slow down the learning process. hence, the image pixels were scaled (normalized) between 0 and 1. a series of array values of images pixel saved as one variable and later reloaded to save processing time when using this data for the second time. after selecting the target label, it was changed into series of array elements and finally binarize the labels into 0’s and 1’s using the label binarize function to be understood by sigmoid activation function (zhao et al., 2014). hence, the system used a binary classifier internally for each 5 target labels. even though the color feature consumes computational time to process the image, rgb image used to avoid loss of some useful features. 2.6. model building (transfer learning) 2.6.1. feature extraction the fine-tuned models of cnn such as mobile net, vgg16, and inception_v3 are adopted to extract useful leave features and feed them to the classifier. these feature extractions are processed in the feature learning layer part of cnn as indicated in figure 5. this is achieved with the help of filtering kernel that slides over the image pixels and compute dot product to produce different image features, max pooling to reduce the spatial size of the convolved image features, and relu activation function to allow the models learn faster and better by overcoming the problem of vanishing gradient problem. in this feature extraction, the deep learning model extracts the necessary features of the plant leaf automatically. figure 5: structure of convolutional neural network misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 100 2.6.2. how cnn internally extract leaf features figure 6 shows how cnn extract leave features. at 1st, it detects simply identifiable patterns like horizontal and vertical lines present in leaves. at the 2nd layer, it can detect different corners on leaves as a result it tries to identify the shape of leaves. at the 3rd layer, it further computes more complex feature map identification like extracting differently structured veins on the surface of leaves. at the 4th layer, it becomes more power full to exploit each tiny vein structure and while going to a very deep layer it can identify the ubiquitous structure. so, by going through this execution cnn can identify leaves unique features for classification. in this study, feature map means the number of image features produced by convolution process. as the image size increases the number of features that are produced by convolution layer will be increases. if there is no padding, the convolution layer reduces the image sizes figure 6: feature extraction process in convolutional neural network 2.6.3. classification this part contains flatten, fully connected neural network, dropout, and sigmoid layer. loss function of binary cross entropy is used because at the end layer, there is a sigmoid classifier shown in equation 1. sigmoid is used as classifier because this study performs five binary decisions (classification) internally to achieve multi label classification. 𝑓(𝑥) = 1 1+exp−𝐱 (1) figure 7 shows the basic technical operations performed. in the figure, f1, f2, f3, ... fn represent features, d1, d2, d3, .... dn represents input image data which is feature vector as 2d array and c1, c2, c3, ... cn represents target classes. figure 7: basic technical operation performed in this study 2.7. train the model to save computational resources and time, the transfer learning techniques are adopted on mobile net, vgg16, and inceprion_v3. the adopted models are pre-trained with the image net. in this procedure some layers of the models are tuned with the new weights and the remaining layers was left to freeze. at the fully connected layer, the new dense layers drops out and batch normalization are added. the advantages obtained from this transfer learning are, the training is completed in a short period of time, no need of large number of training epochs, and also the data needed for training are small. so, to customize these pre-trained models in addition to layer tuning, the deep learning hyper parameters are tuned up on the models. on mobile net the last 4 layers of convolutional base trained with the new weights and the remaining layer was left to freeze. at the fully connected layer, two layers with a 1024 unit and relu activation functions are used. due to this modification total number of layers in mobile net changed from 28 to 30. another interesting thing is batch normalization added at the dense layers to facilitate training rates and obtain good performance with small epochs. on the vgg16, the same changes with mobile net are applied. unlike mobile net, a dropout layer with a value of 0.5 added to overcome the problem of overfitting and only one dense layer is added. on the inception_v3 also applied the same as mobile net and vgg16 except all base convolutional layers frozen and dropout of 0.9 is used at fc. the common hyper-parameters applied on all models are, batch size that is the number of training sample utilize in one iteration (epoch), epochs used as the number of passes to determine how many repetitions a machine learn from input data, learning rate to determine the step size in each iteration, dropout to make some neuron inactive temporarily to overcome the problems of over misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 101 fitting, and optimizers to update weight parameters and minimize error rate during back propagation. 2.8. model performance evaluation to evaluate the models accuracy, precision, recall and f-score, equation 2, 3, 4 and 5 can be used (bekkar et al., 2013). but in this study, we have imbalanced dataset among categories. hence, f1_score is better than the other to measure for the performance of models (jeni et al., 2013) as it is the harmonic mean of recall and precision. 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦 = 𝑇𝑃+𝑇𝑁 𝑇𝑃+𝑇𝑁+ 𝐹𝑃 𝐹𝑁 (2) 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 = 𝑇𝑃 𝑇𝑃+𝐹𝑃 (3) 𝑅𝑒𝑐𝑎𝑙𝑙 = 𝑇𝑃 𝑇𝑃+𝐹𝑁 (4) 𝐹1_𝑆𝑐𝑜𝑟𝑒 = 2 ∗ 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛∗𝑅𝑒𝑐𝑎𝑙𝑙 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛+𝑅𝑒𝑐𝑎𝑙𝑙 (5) where, tp, tn, fp and fn represent true positive, true negative, false positive and false negative respectively. 2.9. multi label setup the parts of the plant are taken as multi label for corresponding plant dataset to classify it as multi label classification. the target class labelled as l= [l1, l2, l3, ln] where l is the list of labels which can be taken as a target class for a given input dataset. ln is an element of (0, 1). for a specific input row from element of target label array, ln=0 means, the input leaf image has no the target label (the label is plant part) and ln = 1 means, input leaf image have that target label. 2.10. working principle of the system figure 8 contains two main parts such as image data processing and target label processing. on the image processing side, after putting image data in a folder and reading the csv file, these two files are concatenated to read a full image file. from a folder, the original image of leaves taken and from the csv file, the corresponding filename of the image taken is labeled in the first column of the csv file. the input image is resized to 128 x 128 and the pixel values are normalized between 0 and 1 to reduce computation time during training. the image pixels are changed into a series of a 2d array to be understandable by computer machines (models) while processing it. the array values of image pixel with the corresponding mapped (labeled) classes are saved as one variable and later reload to save computational time when these data are needed later. two of the columns are dropped from the csv file which holds image name and label tags, and leave the remaining column as the target label of corresponding image files. figure 2-5 indicates the image data and corresponding target labels is split into training and testing set as x-train, x-test, and y-train, y-test to evaluate the models. here 20% of the image data and target label are taken for the test set for one-time cross validation purpose. training set is used to train the model figure 8: over all working principle of the system misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 102 and the testing set is unseen data during training but used later to test the model. further 20% from x-train and y-train data are taken the validation set to cross check whether the model train well or not within each epoch during training. the next tasks are fitting x-train, y-train, and validation data to the model and train it. here fine-tuned mobile net, vgg16, and inception-v3 are used on the train model section. then we test the efficiency of the models using x-test y-test. during this procedure the validity of the model are evaluated and then if the models are performed good, predictions of medicinal plant parts are takes place otherwise tuning of training and model hyper parameters are applied and train the model again until good result is obtained. 2.11. experimental setup for the experimental analysis, first all image data with corresponding target labels are uploaded to google drive and the data further mounted to google colab. then google colab with free 12 gb ram and tesla k80 gpru0.0 is used for data preprocessing, model building (training), testing, evaluation and predication (classification). the data is split to 80% for training and 20% for test. 15,100 total medicinal plant images are prepared. from this data first 20% are taken for testing which are 3,020 images and the remaining 12,080 data taken for training. from 12,080 data, again 20% (2,416 images) is taken for validation. so, the data are split in to 9,664 for training, 3,020 for testing (unseen data during training), and 2,416 for validation. in all models, weights of image net and custom weights are used and the dense layer removed and replaced with new convolutional layers including batch normalization and dropout layer. batch normalization to increase the speed of learning and acquire higher accuracy values. for the trained models in each experiment, the best optimizer is selected and mentioned in the table with the corresponding batch sizes. different deep learning hyper parameters are tuned to come up with the best solution (table 2). 3. results and discussion 3.1. mobile net as indicated in table 3, adam gave a good result based on training and testing losses. even though rmsprop score higher result in training and testing accuracy, it did not reduce the losses. figure 9 shows the best case of training and validation accuracy/loss of fine-tuned mobile net model using adam and rmsprop optimizer, with batch size of 32 and 128. this model gives a higher result with this specified batch size and optimizers. table 2: hyper parameter tuning hyper parameter mobilenet vgg16 inceptionnet batch sizes 32 applied applied applied 64 >> >> >> 128 >> >> >> learning rates 1e-4 >> >> >> 1e-3 >> >> >> optimizers adam >> >> >> adamax >> >> >> adagrad >> >> >> rmsprop >> >> >> dropout ………… ………. 0.5 0.9 weight modification >> >> not used table 3: training and testing accuracy/loss of mobile net batch size optimizers training accuracy testing accuracy training loss testing loss 32 adam 92.59 92.15 0.34 1.29 rmsprop 93.33 91.82 0.87 3.03 64 adam 91.83 91.69 0.36 1.39 128 adam 92.32 91.75 0.28 1.22 rmsprop 92.63 92.12 1.63 3.99 misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 103 figure 9: training and testing accuracy/loss using optimizer adam and rmsprop respectively 3.2. vgg16 training and testing accuracy/loss of vgg16 is included in table 4. using batch size 32 and adamax gives preferable result but rmsprop using batch size 64 and adam using batch size 128 gives valid accuracy. when compared among loss values adam using batch size 128 gives an acceptable result. so, adam is taken as a good optimizer for vgg16. 3.3. inception_v3 as seen from table 5, inception_v3 cannot give a satisfactory result compared to mobile net and vgg16. but when compared by itself rmsprop gives good results on the batch size of 32, 64, and 128. generally, when we look in to the result analysis, mobile net is a good and fastest classifier than vgg 16 and inception net. the reason behind is that mobile net constructed by depth wise separable convolution layers that makes the model to learns fast and reduce the problem of overfitting. the advantage of using depth wise separable convolutional layer is to reduce the value of total scalar multiplications produced by convolution process. 3.4. accuracy of models with batch normalization in this part, the study tried to show the empirical result of training accuracy, testing accuracy, training loss, and testing loss (figure 10 and 11) with the presence of batch normalization at fully connected layer of cnn. since our data is imbalanced, in this study accuracy is not used to measure the performance of the models. because accuracy places more weight on the large classes than on small classes, which makes it difficult for a classifier to perform well on the rare classes, it become a misleading indicator (bekkar, et al. 2013). table 4: training and testing accuracy/loss of vgg16 batch size optimizers training accuracy testing accuracy training loss testing loss 32 adamax 88.86 86.95 0.39 1.69 64 rmsprop 91.71 90.83 0.64 1.6 128 adam 91.78 90.93 0.4 1.33 table 5: training and testing accuracy/loss of inception net batch size optimizers training accuracy testing accuracy training loss testing loss 32 rmsprop 74.30 70.93 7.67 11.23 64 rmsprop 74.77 71.32 6.58 10.27 128 rmsprop 75.2 72.25 6.31 9.83 misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 104 figure 10: training and testing accuracies of the models figure 11: training and testing losses of the models 3.5. accuracy of models without batch normalization figure 12 and 13 shows an experimental result of all model accuracy and loss for both training and testing datasets respectively. this is taken as higher in case of training the models without batch normalization. but it is almost the same as the worst case of models with batch normalization. figure 12: training and testing accuracies of the models without batch normalization figure 13: training and testing losses of the models without batch normalization misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 105 3.6. performance evaluation to measure the performance of models, this study used the hyper parameters, the effect of batch normalization when it is added at fully connected layer of cnn and the type of convolutional layer such as depth wise separable and standard convolutional layer as evaluation benchmarks. the dataset in each category is not balanced (each category has different amount of data). hence, when there are datasets that have unbalanced classes a better choice is f1_score, which can be interpreted as a weighted average of the precision and recall values (jeni et al., 2013). as indicated in figure 14, mobile net performs good using a batch size of 32 and optimizer of adam and rmsprop. this indicates that mobile net is well trained on a new medicinal plant data than other models. figure 14: model performance evaluation result of the models figure 15: comparison of model (mobile net) accuracy with and without batch normalization in figure 15, the study tried to show performance comparison of with and without batch normalization by applying on mobile net. as indicated, for multi label classification mobile net without batch normalization decreases the accuracy by 8.2 % and 13.9 % using adam and rmsprop respectively. this is a big difference and hence for image classification based on multi label technique application of batch normalization on the dense layers of convolutional neural network is highly recommended. 3.7. classification report figure 16 represents the confusion matrix on which the models are measured with the test data set by observing how many test samples of the data are classified correctly and how many are misclassified in each class (category). this classification report is taken as the best performance from the 72 experiments. the result is obtained using a learning rate of 1e-4, batch size of 32, and optimizer of adam. the right side of the figure shows how many of the sample data are classified in true positive (tp), false positive (fp), true negative (tn), and false negative (fn) in each of the five classes. the root of the plant is taken as an illustration for the confusion matrix. it has the true positive value of 732, false-positive value 4, true negative 2,223, and false negative 61. hence, the root has a total test data of 793. from these data, 732 samples are classified into the root category, 2 samples are misclassified as leaf and seed, 2 samples are misclassified as unidentified. this shows the model misses only 0.5 % of the correct classification and a desirable result of the classification handled by mobile net. table 6 is taken from the classification report of mobile net to show the performances of the model in each category (class). the results of f1_score is taken for the description because this evaluation metric takes the advantages of both precision and recall by making the harmonic mean of precision and recall. the f1_score shows, the model obtained the adequate performances on both classes. it is also possible to make sure by referring from the above confusion matrix. the prediction results at the end of this section also another evidence for the performance of a model that is adopted in this study. misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 106 figure 16: confusion matrix of the best model (mobilenet) table 6: performance measurement results of the best model (mobilenet) 3.8. prediction the following screenshot is taken from the sample demonstration which indicates as the model can predict the medicinal plant parts effectively. the parts that have the percentage value approaches to 1 means the model classify accurately. no matter about the value 1 and 0.9, figure 17: samples of medicinal plant predicted by trained model categories (classes) precision in% recall in % f1_scoer in % no. of test data root 99 92 96 793 bark 100 89 94 225 leaf 96 92 94 1350 seed 72 99 84 363 un identified 100 98 88 289 micro average 94 94 94 3020 macro average 94 94 93 weighted average 95 94 94 misganaw aguate et al. ethiop.j.sci.sustain.dev., vol. 8 (2), 2021 107 it is simply calculated as the decimal point. it is easy to make it whole number by multiplying by 100 and change to 100 % and 99%. 4. conclusion and recommendations this research is the first to classify the specific parts of medicinal plants using multi-label classification. since there is no published medicinal plants data based on their specific parts, the dataset is prepared based on the reference of pathobiological researches and consultation of experts who are currently working on preparations of traditional medicine. from the observation of data collections, leave part of the plants takes the majority role in curing diseases. based on the experimental results, we can conclude that over fitting of the models does not only depend on the number of a data set and the depth of hidden layers in cnn, it is also determined by the total number of scalar multiplication of filters (kernel) calculated by the convolution process. in this study, mobile net contains 30 convolutional layers and vgg16 has only 16 layers. but the mobile net does not over fit than vgg16, because it uses depth wise separable convolution technique. this technique reduces the scalar multiplication of the kernel by a factor of 1/20. so, the total number of scalar multiplications calculated in mobile net is very small compared to vgg16. that is why mobile net does not over fit even though it has the maximum number of convolutional layers than vgg16. in this study, three main pillar points are identified: 1) batch normalization at the fully connected layers of the cnn makes the model learn faster in a small number of training epochs, 2) the utilization of plant leaves image from its backside enables the models to extracts the vein features accurately. the combined effect of the two cases leads the model to score a good performance while it is tested by unseen (new) data, and 3) depth wise separable convolution highly determines the over fitting and under fitting conditions of the models. finally, this study deduced that using a learning rate of 1e-4, batch size of 32, and optimizer of adam, the models achieved classification performances of 94%, 86%, and 68% for mobile net, vgg16, and inception_v3, respectively. this result is based on f1_score evaluation metric. generally, after conducting more than 72 experiments on 15,100 images of medicinal plants, the study concludes mobile net is the fastest model to train and test medicinal plant parts. this model is also selected as a suitable deep learning technique to come up with a good solution for the identified problems by achieving higher classification performance than vgg16 and inception_v3. this study introduces the idea and testing of the identification and classification of medicinal plant parts using deep learning technique based on multi label categories to answers the question of which part of medicinal parts are used to medicine preparation? but the study does not incorporate the identification of diseases cured by the identified parts of the plants, limited with small number of data sets, and the optimal learning rate is manually searched using grid search method. for the future work, we recommend researchers to incorporate the following concept for more relevant results:  it is good using fastai (a deep learning library running on top of pytorch) to make the classification task easier and fast by finding the optimal learning rate using learning rate finder.  increasing the number of data set will leads the model to obtain accurate results.  if researchers incorporate the corresponding diseases to be cured by specified parts, the output of a system will be more useful and relevant.  if the future researcher works on the way that can increase the model performance, using multi label classification makes the research finding appreciable. reference amuthalingeswaran, c., sivakumar, m., renuga, p., alexpandi, s., elamathi, j., & hari, s. s. 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(2020). deep learning for plant species classification using leaf vein morphometric. ieee/acm transactions on computational biology and bioinformatics, 17(1): 82– 90. https://doi.org/10.1109/tcbb.2018.2848653 53 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper evaluation of different blended fertilizers types and rates for improving the productivity of wheat (triticum aestivum l.) in debub ari district, south-western ethiopia abebe hegano, atinafu tunebo, shemelis tesema southern agricultural research institute, jinka agricultural research center, p.o.box 96, jinka, ethiopia article info abstract article history: received 06 march 2022 received in revised form 19 june 2022 accepted 30 june 2022 crop specific fertilizer recommendation is necessary for sustainable crop production. accordingly, a field experiment was conducted in debub ari district, southern ethiopia, to evaluate blended fertilizer types and rates effect on improving the production of wheat during the main rainy season of 2018 and 2019. the experiment was laid out in randomized complete block design with three replications. the 9 treatments used for the field experiment were 1) control, 2) (142 nps + 42 urea) kgha-1, 3) (189 nps + 72 urea) kgha-1, 4) (237 nps +102 urea) kgha-1, 5) (142nps + 159 urea) kgha-1, 6) (150npsb+ 41urea) kgha-1, 7) (200 npsb + 72 urea) kgha-1, 8) (250npsb + 102urea) kgha-1 and 9) (150 npsb + 161urea) kgha-1 treatments. application of blended fertilizer significantly (p < 0.05) increased the plant height, number of tillers per plant, spike length, number of seeds per spike, grain yield, aboveground biomass, and thousand seed weight at harvest as compared to the control. the maximum and significant grain yield (3796.7kg ha-1) and minimum (1466.5 kg ha-1) were obtained from the application of 237 kg ha-1 nps + 102 kgha-1 urea and unfertilized treatment, respectively. the application of 237 kg ha-1 nps + 102kgha-1 urea had a maximum and acceptable marginal rate of return (mrr %) and net benefit. therefore, this type and rate of blended fertilizer can be recommended since it produced a high marginal rate of return, high net benefit, and relatively low total cost of production, for wheat production in the study area and other similar agroecologies. keywords: blended fertilizer wheat grain yield biomass 1. introduction wheat (triticum spp.) is the major cereal crop grown in the highlands of ethiopia (efrem et al., 2000). it is well-produced across a wide range of soil conditions, although it is best adapted to fertile, well-drained silt and clay loam soils (bekele et al., 2000). in ethiopia, it ranks fourth in a total area of cereal grains coverage of 13.38% (1.69 million ha) and third in cereal grain production (15.17% (4,642.96 million t)) next to maize and tef, and in snnpr wheat ranks third in area coverage (0.13 million ha) and also it ranks third in grain e-mail: abehegeno@gmail.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.414 production (339.19 million t) next to maize and tef (csa, 2018). despite the long history of wheat cultivation, its high cover of production area, its productivity, and its importance to the ethiopian agriculture, its average yield is still very low, not exceeding 2.74 t ha-1 nationally and 2.67 t ha-1 regionally (csa, 2018) as compared to the world average 3.0 t ha-1 (faostat, 2013). the low yield and reduction in productivity of wheat could be due to low soil fertility, in addition to other biotic and abiotic factors (tesfaye, 1988). http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.414 abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 54 inadequate agronomic and soil management, insufficient level of technology generation and dissemination are the most significant problems to enhancing bread wheat production in ethiopia. on the other hand, low soil fertility followed by slow progress in developing wheat with durable resistance to disease, pests and weeds is considered the most important constraint limiting bread wheat production in ethiopia (demeke and dimarcantonio, 2013). soil fertility improvement requires a balanced application of inorganic and organic nutrient sources (teklu and hailemariam, 2009). inorganic fertilizers have been the important tools to overcome soil fertility problems and they are also responsible for a large part of the food production enhancement worldwide (sanchez et al., 1997). it has been estimated that at least 30 to 50% of crop yield increment is attributable to the application of commercial fertilizers (stewart et al., 2005). plants require essential nutrients with adequate amounts for better production (alloway, 2003). however, in ethiopia, only di-ammonium phosphate (dap) and urea for the past many years has been used for crop production. according to (ata, 2016), in addition to nitrogen and phosphorous, other nutrients like sulfur, potassium, boron, zinc, and copper are identified as low in ethiopian soil and are needed to address the key nutrient deficiencies. the soil of the study area lacks some major macronutrients like nitrogen and phosphorus, secondary macronutrients like sulphur, and some micronutrients especially boron; not only in the study area most of the soil of debub ari district lacked the above nutrients (ata, 2016). therefore, this study was done with the general objective of evaluating the effect of blended fertilizer types and rates on growth, yield, and yield components of wheat production. 2. materials and methods 2.1. description of the study area the experiment was conducted at debub ari district south omo zone, southwestern ethiopia for two consecutive years (2018 and 2019) during main cropping season. geographically, the site is located at 05°50’ n and 36°41’ e with an altitude of 1930 m.a.s.l. it is found in the northeastern direction at a distance of 18 km from jinka town. the experimental site has a bimodal rainfall pattern with a shorter rainy season from march-may and the longest rainy season from august to november. the long-term mean annual is 1342.03 mm and the maximum and minimum monthly average temperatures of the study area are 27.61 and 16.3°c, respectively. 2.2. treatments and experimental design the experiment having nine treatments was laid out in a randomized completely block design (rcbd) with three replications with a plot size of 4m*4m. net plot size 3m*4m was used for the data collection. the treatments consists of four rates of nps and four rates of npsb blend viz. control (no fertilizer), 142 kg nps + 42 kg urea, 189 kg nps + 72 kg urea, 237 kg nps + 102 kg urea, 142 kg nps + 159 kg urea, 150 kg npsb + 41 kg urea, 200 kg npsb + 72 kg urea, 250 kg npsb + 102 kg urea, and 150 kg npsb + 161 kg urea. the amount of nutrients present in applied blended fertilizers is explained in table 1. a blended fertilizer nps and npsb were used based on soil fertility and fertilizer type recommendation atlas map for snnprs (ata, 2016). a full dose of nps and npsb was applied in the rows mixed with soil just at the time of planting. whereas nitrogen was split twice, half was applied at planting, and a half was applied 35 days after planting. improved wheat variety was used for the experiment, and all management practices were applied as per research recommendations for wheat. all necessary agronomic and soil data collection were done at appropriate crop growth stages following recommended procedures. 2.3. data collection 2.3.1. agronomic characters data for yield and yield components were collected as per the procedures mentioned as follows. for plant height, five plants from the central rows of each plot were randomly selected. then the average values of these plants were recorded. grain yield and biomass were determined by harvesting the entire net plot area and converted into kilograms per hectare. thousand seed weight was counted at random from total grain yield and weighed by using sensitive balance and expressed abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 55 table 1: treatments description, fertilizer rates and their composition no. treatments nutrient contents (%) in fertilizers types n p2o5 s b 1 no fertilizer 2 142 nps+42 kg urea 46 54 10 3 189 nps +72 kg urea 69 72 13 4 237 nps+102 kg urea 92 90 17 5 142 nps+159 kg urea 92 54 10 6 150 npsb+41 kg urea 46 54 10 1.07 7 200 npsb+72 kg urea 69 72 13 1.4 8 250 npsb+102 kg urea 92 90 17 1.7 9 150 npsb + 161kg urea 92 54 10 1.07 in grams. number of tillers per plant, spike length, and number of seeds per spike were also recorded. 2.3.2. soil sampling soil samples were randomly taken from the experimental field at a depth of 0 to 20 cm using an auger in a zigzag pattern, and composited into one sample before sowing the crop. before analysis, the samples were air-dried and ground to pass through a 2 mm sieve for analysis of selected soil physicochemical properties other than organic carbon (oc) and total nitrogen (tn), which were ground to pass through a 0.5 mm sieve to remove course materials. the soil samples were analyzed using standard soil laboratory procedures at jinka agricultural research center soil laboratory. 2.4. data analysis the collected data was subjected to analysis of variance (anova) as per the design used in the experiment sas version 9.1 statistical software. least significant difference (lsd) was used to separate means at (p<0.05) probability levels of significance (sas institute, 2007). pearson correlations were done to determine linear associations between agronomic parameters. 2.5. partial budget analysis for the economic evaluation, partial budget and marginal analyses were performed to investigate the economic feasibility of inputs at planting and for outputs at the crop harvest. current prices of wheat, urea and blended fertilizer were used for the analysis. the potential response of crop towards the added fertilizer and price of fertilizers during planting ultimately determine the economic feasibility of fertilizer application (cimmyt, 1988). the gross benefit ha-1 is the product of field price and the mean yield for each treatment. the total variable cost (tvc) is the sum of the cost of fertilizer and the cost of fertilizer application. the net benefit per hectare for each treatment is the difference between the gross benefit and the total variable costs. for each pair of treatments, a percent marginal rate of return (mrr) was calculated. to obtain an estimate of these returns, mrr was calculated using the following formula: mrr (%) = change in net benefit (nb2 − nb1) ∗ 100 change in tvc (tvc2 − tvc1) where, nb1net benefit at level one; nb2net benefit at level two; tvc1-total variable cost at level one and tvc2-total variable cost at level two. 3. results and discussion 3.1. soil fertility status before planting the analyzed soil data before planting indicated that the textural class of the surface soil was clay and the soil was moderately acidic (ph 5.61) with high organic carbon (°c) and total nitrogen (tn) contents (tekalign, 1991) (table 2). available phosphorus (p) content (3.59 ppm) was very low (jones, 2003) and it is indicative of soil has probable yield responses to p application. available b content of the soil in the experimental field was low (jones, 2003). according to hariram and dwivedi (1994), the available sulfur content of the soil in the experimental field is 18.46 ppm which is high. abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 56 table 2: some soil physical and chemical properties of the experimental site before planting in debub ari during the 2018 and 2019 cropping seasons soil properties values rates references clay 69 silt 20 sand 11 textural class clay ph(h2o) 5.61 moderately acidic jones, 2003 organic carbon (%) 3.54 high tekalign, 1991 total n (%) 0.25 high tekalign, 1991 available p (ppm) 3.59 very low jones, 2003 available s(ppm) 18.46 medium hariram and dwivedi, 1994 available b (ppm) 0.12 low jones, 2003 generally, the soils of the experimental field had characterized to be low available p, b, and s which indicated that potentially reduced the yield of wheat production. however, the soils of the study site had high oc and tn. thus, an additional application of p, b, and s have enhanced the grain yield of wheat in the study area. 3.2. growth parameters 3.2.1. plant height the result analysis of variance indicated that the applied blended fertilizer types and rates significantly (p<0.05) affected the plant height of wheat. the highest plant height (85.57 cm) was recorded from the application of 237 kg nps + 102 kg urea (92n, 90 p2o5, 17s) ha-1. however, the lowest plant height (67.17 cm) was recorded from the control plot, but the other treatments were statistically non-significant from each other (table 3). the increment in plant height might be due to the greater role of n applied for elongation and vegetative growth of wheat. on the other hand, the minimum plant height in control plots might have been due to low soil fertility status in the experimental field. a similar result was also reported by sofonyas et al. (2021) who reported that the application of 300 kg of npszn ha-1 blended fertilizer significantly increased the plant height of bread wheat compared to unfertilized treatments. haji et al. (2020) also reported that the maximum plant height (118.06 cm) was obtained from the application of 200 kg nps ha-1 blended fertilizer while the minimum (86.2 cm) was obtained from control treatments. 3.2.2. spike length spike length of wheat was significantly (p<0.05) affected by the applied blended fertilizer types and rates as compared to the unfertilized plot. the maximum spike length (8.85cm) was recorded from the application of 237 kg nps + 102 kg urea ha-1 while the minimum spike length (7.77 cm) was recorded from the control plot (table 3). however, there was a non-significant difference was observed within applied blended fertilizer. similar to this result, haji et al., (2020) reported that the maximum (9.37 cm) spike length was obtained from 200 kg npsb ha-1 blended fertilizer whereas the minimum (6.14 cm) was from the control (unfertilized) treatment. the spike length increment with the blended fertilizer application might be supplying better photo assimilation (berhan, 2012). the author also observed that the higher the spike length produced the higher grain per spike leading to a higher yield. 3.3. yield and yield components 3.3.1. number of tillers per plant number of tillers per plant significantly (p<0.05) influenced by the application of blended fertilizer types and rates as compared to unfertilized treatments. the maximum number of tillers per plant (6.1) was obtained abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 57 with the application of blended fertilizer 237 kg nps + 102 kg urea (92n, 90 p2o5, 17s) ha-1, while the minimum number of tillers per plant (3.45) was obtained from the unfertilized plots (table 3). this result is in line with that of seyoum (2017), who reported that the highest number of tillers per plant of bread wheat due to the combined application of 200 kg nps + 92 kg n ha-1 indicates the positive role of the optimum rate of nitrogen for tillering. 3.3.2. number of seeds per spike the analysis of variance showed that there was a significant difference among the applied blended fertilizer types and rates (p≤0.05) on the number of seeds per spike. the highest number of seeds per spike (38.6) was obtained from the plot treated with 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1, while the lowest (23.8) was recorded from the control treatment (table 3). the maximum rate of nps blended fertilizer enhanced the number of seeds per plant by 62% over the control treatments. in agreement with this result, abebual et al. (2019) reported that a maximum (50.47) number of seeds per spike of wheat were obtained from the application of the npsznb (175n+125p2o5+11.1s+3.3zn+0.15b) kg ha -1 fertilizer rate while the minimum (32.73) was obtained from the control plot. 3.3.3. thousand seed weight the analysis of variance showed that thousand kernel weight was significantly affected (p ≤ 0.05) by the different blended fertilizer types and rates. the maximum thousand kernel weight was obtained from the rate of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha-1 (table 3), which is higher by about 27% as compared to thousand kernel weight obtained from the unfertilized plot. this result is in line with dinkinesh et al. (2020), who reported that a maximum (44.8 g) 1000 kernels weight with the application of 183 kg npsb ha1 rate while the minimum (37.2 g) was recorded from an unfertilized plot. 3.3.4. above ground biomass the aboveground biomass was significantly (p < 0.05) influenced by the application of blended fertilizer types and rates as compared to the unfertilized plot. the maximum aboveground biomass (7652.8 kg ha-1) was obtained from the application of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha-1 whereas the minimum aboveground biomass (4086.8 kg ha-1) was recorded from the control (table 3). application of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1 increases aboveground biomass by 87.3% as compared with the unfertilized treatment. the increment of aboveground biomass might be due to improvement of root growth and increased uptake of nutrients favoring better growth and tillering (dinkinesh et al., 2020). similarly, abebual et al. (2019) reported that the highest total biomass (14290 kg ha-1) from the treatment with the application of npsznb (175n+125p2o5+11.1s+3.3zn+0.15b) kgha-1, while the minimum (3390 kg ha-1) was recorded from the control treatment. 3.3.5. grain yield the analysis of variance revealed that the different level of blended fertilizer types had a significant (p<0.05) influence on the grain yield production (table 3). the study showed that the maximum grain yield of 3796.7 kg ha-1 was obtained from the plots maintained by 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1 application whereas the minimum 1466.5 kgha-1 was obtained from unfertilized plots (table 3). application of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha-1 improves grain yield production by 58.9% as compared to the unfertilized plot. the maximum grain yield from the highest nps rates with optimum n amounts might have due to resulting in improved root growth and enhanced uptake of nutrients which increased yield and yield components. similar result was obtained by abebual et al. (2019) who reported that the highest grain yield (5770 kgha-1) obtained from the application of npsznb (175n+125p2o5+11.1s+3.3zn+0.15b) kg ha -1 whereas, the lowest was recorded from unfertilized plots. similarly, dinkinesh et al. (2020) reported that the treatments that received blended fertilizers of 183 kg ha-1 npsb increased grain yield of wheat as compared to the control. sofonyas et al., (2021), also reported the maximum grain yield of wheat (3580.2 kg ha-1) was obtained from 200 kg npszn ha-1 fertilizer application over the unfertilized plot. abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 58 table 3: growth, yield and yield components of wheat as influenced by blended fertilizer type and rate in debub ari during the 2018 and 2019 cropping seasons treatments (kg/ha) no. of tiller per plant ph (cm) spike length (cm) seed/spike tsw (gram) biomass (kgha-1) yield (kgha-1) no fertilizer 3.45c 67.17d 7.77c 23.8c 32.49e 4086.80d 1466.50d 142 nps + 42 kg urea 4.42bc 77.73b 8.16bc 31.27b 39.47ab 5692.70bc 2768.20b 189 nps + 72 kg urea 4.33bc 78.67b 8.55ab 30.57b 37.83bc 6062.50bc 2618.90bc 237 nps + 102 kg urea 6.10a 85.57a 8.85a 38.60a 41.17a 7652.80a 3796.70a 142 nps + 159 kg urea 3.97bc 74.07c 8.08bc 32.67b 34.78de 5274.30cd 2166.50c 150 npsb + 41 kg urea 4.47bc 79.37b 8.08bc 29.97b 38.63abc 5921.90bc 2567.60bc 200 npsb + 72 kg urea 4.00bc 79.30b 8.35abc 29.80b 38.06bc 6597.20ab 2806.10bc 250 npsb + 102 kg urea 4.53b 77.33b 7.77c 32.67b 39.04abc 6489.60ab 2608.00bc 150 npsb + 161kg urea 4.53b 78.43b 8.35abc 32.80b 36.35cd 6.39.90bc 2750.40b lsd (5%) 1.06 2.87 0.61 5.53 3.03 1210.6 554.43 cv 13.85 2.14 4.29 10.2 4.67 11.69 12.24 nb. means with the same letter are statistically not significant at 5% level of significance, cv=coefficient of variation, lsd= least significance difference, ph= plant height, tsw= thousand seed weight 3.4. correlation analysis correlation between growth and yield components of common bean as influenced by the application of blended fertilizers was computed and its results are presented in table 4. significant and positive correlation of grain yield with the other yield components was observed. this indicates that, grain yield of wheat could be invariably enhanced by increasing those characteristics. grain yield was significantly and positively associated with number of tillers per plant (r= 0.65***), plant height (r= 0.83***), spike length (r= 0.49*), number of seeds per spike (r= 0.58**), above ground biomass (r= 0.79***) and thousand seed weight (r= 0.84***) (table 4). the result indicated that the applied fertilizers have significant and positive contribution to the economic yield. this result was supported by the recent findings of abebual et al. (2019) who reported that significant and positive association of grain yield with number of tillers per plant, plant height, spike length, number of seeds per spike, above ground biomass and thousand seed weight was observed on bread wheat. table 4: correlation coefficients between mean agronomic parameters of wheat grown under blended fertilizers ntp ph sl nss bm gy tsw ntp 1 ph 0.61*** 1 sl 0.46* 0.53** 1 nss 0.62*** 0.64** 0.47* 1 bm 0.66*** 0.79*** 0.36ns 0.63*** 1 gy 0.65*** 0.83*** 0.49* 0.58** 0.79*** 1 tsw 0.53** 0.73*** 0.27ns 0.49* 0.77*** 0.84*** 1 note: ntpnumber of tillers plant-1, phplant height, sl-spike length, nssnumber of seed spike-1, bmaboveground biomass, gy-grain yield, tswthousand seed weight, ns non-significant and *, ** *** stands for significantly different at 5%, 1%, and 0.1%, respectively. abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 59 3.5. partial budget analysis the partial budget analysis was significantly affected by the application of different blended fertilizer types and rates (table 5). according to the economic analysis, a maximum net benefit of 56550.08 etb ha-1 was obtained from the plot received from 237 kg nps + 102 kg urea ha-1 which was economically superior treatment, followed by 142kg nps + 42 kg urea ha-1 blended fertilizers, which had a total net benefit of 40200.92 etb ha-1. while the minimum net benefit (27716.85 etbha-1) was obtained from unfertilized plots (table 5). the highest net benefits from the application of blended fertilizers for the production of the wheat might not be enough for the farmers to accept as good practices but also farmers prefer the highest profit i.e. with low cost and high income. for this purpose, it is necessary to conduct a marginal rate of return and dominated treatment analysis (cimmity, 1988). to determine treatments with the maximum return to the farmer investment, marginal rate of return and dominant analysis was performed over the control treatment. the maximum marginal rate of return (16151.8%) was obtained from the application of 237 kg nps + 102 kg urea ha-1 blended fertilizer (table 6). therefore, the result revealed that the application of 237 kg nps + 102 kg urea ha-1 blended fertilizer gives 16151.8%, which is well above the 100% minimum rate of return, which was considered as the optimum for the recommendation. this treatment shows the maximum net benefit, relatively low variable cost, and acceptable marginal rate of return when compared with the other treatments. table 5: partial budget analysis of blended fertilizer type and rates on wheat production in debub ari during the 2018 and 2019 cropping seasons no. treatments (kg/ha) variables average yield kgha-1 10%adjusted yield kgha-1 gross benefit (etb ha-1) total variable cost (tvc) (etb ha-1) net benefit (etb ha-1) 1 control (no fertilizer) 1466.5 1319.85 27716.85 0 27716.85 2 142 kg nps + 42 kg urea 2768.2 2491.38 46259.95 6059.03 40200.92 3 189 kg nps + 72 kg urea 2618.9 2357.01 42340.65 7156.56 35184.09 4 237 kg nps + 102 kg urea 3796.7 3417.03 64818.16 8268.08 56550.08 5 142 kg nps + 159 kg urea 2166.5 1949.85 32678.77 6939.47 25739.3 6 150 kg npsb + 41 kg urea 2567.6 2310.84 42149.49 6378.15 35771.34 7 200 kg npsb + 72 kg urea 2806.1 2525.49 45429.01 7606.28 37822.73 8 250 kg npsb + 102 kg urea 2608 2347.2 40471.46 8819.74 31651.72 9 150 kg npsb + 161 kg urea 2750.4 2475.36 43843.54 8139.02 35704.52 10% adj. yield= marketable yield adjusted to 10% downward; etb= ethiopian birr table 1: dominance and marginal analysis, wheat yield production by blended fertilizer type and rate in debub ari during the 2018 and 2019 cropping seasons treatments (kg/ha) variables 10% adjusted yield kgha-1 tvc (etbha-1) net benefit (etbha-1) dominance analysis mrr (%) no fertilizer 1319.85 0 27716.85 142 kg nps + 42 kg urea 2491.38 6059.03 40200.92 nd 206.04 150 kg npsb + 41 kg urea 2310.84 6378.15 35771.34 d 142 kg nps + 159 kg urea 1949.85 6939.47 25739.3 d 189 kg nps + 72 kg urea 2357.01 7156.56 35184.09 d 200 kg npsb + 72 kg urea 2525.49 7606.28 37822.73 d 150 kg npsb + 161kg urea 2475.36 8139.02 35704.52 d 237 kg nps + 102 kg urea 3417.03 8268.08 56550.08 nd 16151.8 250 kg npsb + 102 kg urea 2347.2 8819.74 31651.72 d treatments which carries d = dominated and nd= non-dominant abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 60 4. conclusion and recommendation the application of blended fertilizer types and rates showed significant differences for yield and yield components of wheat. the application of blended fertilizer at the rate of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1 resulted in the maximum grain yield, total biomass, plant height, number of tillers per plant, spike length, number of seeds per spike, and thousand kernels weight. the current study revealed that the maximum grain yield of 3796.7kg ha-1 was obtained from the plots received 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1 of blended fertilizer application. the partial budget analysis also indicated that the maximum net benefit (56550.08 etb ha-1) with acceptable marginal rate of return (mrr %) 16151.8% was obtained with application of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1 blended fertilizer. thus, based on the grain yield and economic analysis, the application of 237 kg nps + 102 kg urea (92n, 90p2o5, 17s) ha -1 blended fertilizer can be recommended for debub ari district and other areas with similar agro-ecology and soil conditions. however, to reach at a further recommendation, further investigations are needed each nutrients omission and commission and blended fertilizer formulation types. acknowledgements the authors thank southern agricultural research institute (sari) for financially supporting the field experiment. and also very grateful to jinka agricultural research center for the analysis of the soil parameters and for the facilitation of the vehicle and other accommodations to conduct the research. reference abebual woldetsadik, wondwosen tena & asmare melese (2019). effect of different blended fertilizer formulation on yield and yield components of bread wheat (triticum aestivum l.) in siyadebrenawayu district, north shewa, ethiopia. journal of biology, agriculture & healthcare, 9 (15), 13-23. alloway, b.j. (2003). zinc in soils and crop nutrition. international zinc assocation. pp114. http:// www.zinccrops.org ata (agricultural transformation agency) (2016). soil fertility status and fertilizer recommendation atlas of the southern nations nationalities and peoples’ regional state, ethiopia, by ministry of agriculture and natural resources and agricultural transformation agency, ethiopian, addis ababa, ethiopia. bekele hundie, mawangi, w. & tanner dg. (2000). adaptation of improved wheat technologies in addaba and dodola woredas of the bale high lands of ethiopia cimmyt/earo, addis ababa, ethiopia. bread wheat cultivars released in ethiopia from 1949 to 1987. berhan abayu (2012). agronomic and economic effects of blended fertilizers under planting method on yield and yield components of tef: msc thesis, mekelle university, mekelle, ethiopia. cimmyt. (1988). from agronomic data to farmer recommendations: an economics training manual. completely revised edition. mexico. d.f. csa (central statistics agency) (2018). the federal democratic republic of ethiopia central statistical agency agricultural sample survey report on area and production of major crops (private peasant holdings, meher season), volume i, statistical bulletin 586, addis ababa ethiopia, 2017/18 (2010 e.c.) demeke mekonnen & di marcantonio f. (2013). analysis of incentives and disincentives for wheat in ethiopia. technical notes series, mafap, fao, rome. dinkinesh abera, tamado tana & tadesse dessalegn (2020). effects of blended npsb fertilizer rates on yield and grain quality of durum wheat (triticum turgidum l.) varieties in minijar shenkora district, central ethiopia. ethiopian journal of agricultural sciences, 30(3), 57–76. https://www.ajol.info/index.php/ejas/article/view/198452 efrem bechere, hirut kebede & getachew belay (2000). durum wheat in ethiopia: an old crop in an ancient land. institute of biodiversity conservation and research. addis ababa, ethiopia. faostat (the food and agriculture organization corporate statistical database) (2013). agricultural production statistics. (http://www.fao.org/faostat.) haji jewaro beketa, demelash kefale & tarekegn yoseph (2020). effect of blended fertilizer types and rates on growth, yield and yield components of bread wheat (triticum aestivum l.) in wondo district, southern ethiopia. international journal of agriculture innovations and research, 8(4), 326-342. hariram & dwivedi, k.n. (1994). delineation of sulfur deficient soil group in the central alluvial tract of uttar pradesh. journal of the indian sss, 42, 284-286. jones, j.b. (2003). agronomic handbook: management of crops, soils, and their fertility. crc press llc, boca raton, fl, usa. abebe hegano et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 61 sanchez, a. p. & leakey, r. b. (1997). land use transformation in africa: three determinants for balancing food security with natural resource utilization. agron j., 7, 15-23. sas (statistical analysis systems) (2007). sas/stat user’s guide version 9.1 cary nc: sas institute inc. usa seyoum alemu (2017). effect of blended nps and n fertilizer rates on yield components, yield and grain protein content ofbread wheat (triticum aestivum l.) in bore district, guji zone, southern ethiopia. msc thesis. school of plant sciences, haramaya university, ethiopia. sofonyas dargie, fisseha hadgu, hagos brhane, tsigabu mehari , molla hadis, girmay hailu & daniel berhe (2021). evaluation of npszn blended fertilizer on yield and yield traits of bread wheat (tritcum aestivum l .) on cambisols and vertisols. ethiop. j. agric. sci. 31(2), 33-43. stewart, w. m., dibb, d. w., johnston a. e. & smyth, t. j. (2005). the contribution of commercial fertilizer nutrients to foo d production. agron j. 97, 1-6. tekalign tadesse (1991). soil, plant, water, fertilizer, animal manure and compost analysis. working document no. 13. international livestock research center for africa, addis ababa, ethiopia. teklu erkossa & hailemariam teklewold (2009). agronomic and economic efficiency of manure and urea fertilizers use on vertisols in ethiopian highlands. agricultural sciences in china. 8(3), 352–360. tesfaye tesemma (1988). durum wheat breeding in ethiopia. in:van ginkel, m. and d.g. 18-22.:616. 10 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 application of laser induced breakdown spectroscopy as an alternative method for identification of quality of gold alloys alemu kebede hordofa adama science and technology university, school of applied natural sciences, department of applied physics email: nuuftoleeta@gmail.com abstract in this study a robust and alternative method of gold quality identification is presented. four different karats of gold from different origins were used for investigation. comparison was made between the traditional quantum karat meter and laser induced breakdown spectra to compare their quality. the advantage of the new technique over the karat meter is that the different types of impurities that are found in the gold were clearly identified and their quantities/percentage tabulated. the method is also robust in such a way that it is calibration free. during the experiment, the most resonant atomic line and ionic line of emission of gold were taken at 267.597 nm and at 226.363nm, respectively, in order to reduce the impact of the back ground on the spectral intensities. the experimental result indicated that both atomic and ionic lines of emission were found in very good agreement with quantum karat meter and can reliably be applied as an alternative method of quality control or in a place where such equipment is not available. it was found that the ionic to background and atomic to back ground ratios as well as their normalized intensities were in excellent match with the results from the measured quantum karat meter. keywords: atomic line, ionic line, resonant lines, karat meter 1. introduction different analytical methods have been employed for the quantitative determination of impurities in precious metal alloys. some of these methods include densitometry, determination of gold content on a touchstone, cupellation, and x-ray fluorescence (xrf) [1]. now days laser induced breakdown spectroscopic analysis of precious metals and its alloys is emerging as a key analytical tool for its rapid quantitative as well as qualitative information of the sample. mailto:nuuftoleeta@gmail.com alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 11 © adama science & technology university https://ejssd.astu.edu.et the other advantage of the method is that it does not need internal calibration which is time consuming and difficult for some samples. calibration free laser induced breakdown spectroscopy (cf-libs) has been applied by different researchers in the field even though the application of the method depends on the requirement that the plasma formed during ablation must satisfy the conditions: local thermodynamic equilibrium, optically thin plasma and stoichiometric ablation of the sample [2 4]. in addition, these requirements of (cf-libs) take too much time to analyze every spectrum so that the contribution from each element in the matrix is correctly assessed. the other limitation of the above techniques is their insufficiency in identifying contributions of impurities in gold alloys in determining hardness [6]. recently [5, 6] used low energy laser for rapid quantitative determination of base metal in gold alloys using integrated spectra from each element in the alloy. the method is different from the other libs techniques in that it introduced the use of the number of elements in photosensitive detector array that depends on the spectral resolution capability of spectrometer used. in the current study, integrated ionic and atomic spectra responses are compared with karat values, unlike other techniques. the purpose of this research is therefore to present an alternative, chemical free and robust method to monitor the quality of precious metals quality such as gold using only spectral analysis of libs spectra. 2. materials and methods pure gold and the gold alloys used in this work were purchased from different places and origin, ethiopian and india. pure gold (24 karat) was purchased from (india), 19.5 karat gold was purchased from ethiopian jewelry shop and 9 alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 12 © adama science & technology university https://ejssd.astu.edu.et karat gold was purchased from jewelry shop in allahabad, india. xrf was taken at the jewelry shop, india, and the libs spectra was taken by nd:yag (continuum surelite iii, usa) at second harmonic (532nm) and 10 hz pulse repetition rate. the setup of the experiment is shown in fig.1. figure 1. sketch of the experimental set up libs analysis of gold alloy the x-ray fluorescence (xrf) data was taken from the jewelry shop using quantum karat meter (quantum equipment corporation ltd). gold samples under investigation were mounted on rotational stage to scan the sample with the pulsed laser in all direction. the converging lens converges the laser beam on to the sample at the required angle and position. spectra from the sample were collected using a collection lens that feeds to the optical fiber. the spectrometer disperses the laser beam into different wave lengths. the final emission spectra read out was collected and interpreted from a personal computer that has an ocean optics software which is important for analysis. the fundamental equations for analysis of emission spectra alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 13 © adama science & technology university https://ejssd.astu.edu.et           i b a k cd i b a k zn i b ak i b a i b a k cu k ag k au j cd i cd j zn n j au i au j ag i ag j cu i cu n i i n i i n i i n i i n i i ,,,, depend on calculation of emission intensities. the following mathematical relation was applied to determine total ionic and atomic resonant line spectra to calculated integrated intensities. (1) where c is the number of elements in the photosensitive cells; ik is the intensity at wave length  k by k th element in the photo detector and n is the normalization constant (the detail has been discussed by [6]). the normalized intensity of the emission from components of the alloy is determined using the formulas: applying equations (1) and (2) the total integrated intensity of all spectral lines of the pure gold and each gold alloy was calculated. in calculating the integrated intensities of the samples all the spectral lines of all the elements indicated by the xray fluorescence (xrf) from table 1 were included. also the normalization constant in each case was calculated and finally the normalized intensity for all the elements in the samples determined. calculation of the normalized intensities in terms of (intensity to back ground ratio) for both ionic and atomic lines of gold using their nonresonant lines was done to study relationships between these quantities and karat of gold alloys. (2) 3. results and discussion the quantum karat meter’s xray florescence data indicated the existence of different impurities in the three gold samples while the pure gold did not show any c n i e j e i b ak k izncdagcuaue   ,,,, alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 14 © adama science & technology university https://ejssd.astu.edu.et impurity. the elements found as impurity were copper, silver, cadmium and zinc. but, there were no zinc impurity found in the sample from ethiopia. the elemental data found by the equipment is tabulated in table 1. record of libs spectra of each of the above pure gold and gold alloys was taken to check whether additional impurities are found in the alloys. accordingly, lines of calcium and magnesium in all the alloys including the pure gold were recorded. other impurities like iron and antimony are also found in the gold alloys. in order to reach at meaningful conclusion intensity versus wave length at non resonant lines for both atomic and ionic lines, karat values versus normalized intensities were analyzed. the following figures and tables indicate the results found. table 1. xrf results from quantum karat meter. origin of the gold karat percentage composition of elements au ag cu cd zn indian i 24 99.9 0 0 0 0 ethiopian 19.5 81.1 7.5 10.4 0.5 0 indian ii 17.2 71.5 11.0 15.5 0.3 1.7 india iii 9.2 38.4 9.1 51.1 3.0 0 alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 15 © adama science & technology university https://ejssd.astu.edu.et 200 250 300 350 400 450 500 50 100 150 200 250 200 250 300 350 400 450 500 50 100 150 200 250 200 250 300 350 400 450 500 50 100 150 200 250 200 250 300 350 400 450 500 50 100 150 200 250 9.2 24 in te ns ity ( co un ts ) wave length (nm) 17.2 19.5 figure 2. emission spectra of different gold alloys figure 3. intensity versus wave length of gold of different karats for atomic line 267.597 nm figure 4. intensity versus wave length of gold of different karats for ionic line 208.2 nm investigation of the integrated spectral intensity of ionic lines to background of gold lines revealed that the purer the gold is, the higher the ratio. the spectral intensity of the gold samples are alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 16 © adama science & technology university https://ejssd.astu.edu.et found in good agreement with the result of the measurement from the karat meter. the gold sample with 9.2 karat, which is the least in the karat range, showed the least integrated intensity. emission from the samples was investigated non resonant atomic and ionic lines for better resolution. figure 4 shows the intensity versus emission wavelength at 208.2 nm. the following tables indicate the normalized intensities, the ionic and the atomic intensities to the integrated background intensity compared to their respective karat values for each type of gold alloy. table 2. gold karat versus corresponding ionic intensity to background ratio table 3. gold karat versus corresponding normalized intensity to background ratio the ratio of the integrated intensity to the background, as indicated in table 2, was also found in direct proportion with the karat value of the four gold alloys. i.e., the ratio increases with increasing value of karat. this confirms that the method employed well agrees with other measurement techniques like x-ray fluoresce for measuring karat of alloys. as indicated in table 3 above the logarithm of all emission intensities, when divided to the background were found to increase from 1.3 to 3.31 as the value of the alloy’s karat increase from 9.2 to 24. finally, as the spectral emission lines involve both atomic and ionic lines of emission, the karat ionic to background ratio 9.2 1.3 17.2 2.6 19.5 3.0 24 3.7 karat normalized intensity (logarithmic) 9.2 1.3 17.2 2.52 19.5 2.68 24 3.31 alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 17 © adama science & technology university https://ejssd.astu.edu.et integrated atomic line spectral intensity was used to check whether the method employed yields similar result. table 4 shows the result found from the analysis. similar to the results found in tables 2 and table 3 the gold alloys’ karat values found from the quantum karat meter showed proportional increase from 6 to 14.26 for atomic line spectral intensity to background ratio as the gold karat values increase from 9.2 to 24 karat. the linear relationship between karat values and corresponding atomic and ionic emission intensities were used as a final proof for the current method. the results of the linear fit for karat versus normalized atomic intensity to back ground ratio and that of karat to normalized ionic intensity (logarithmic) are given in figures 5 and figures 6, respectively. table 4. gold karat versus corresponding atomic line intensity to background figure 5. karat of gold versus normalized atomic intensity karat atomic line spectral intensity to background ratio 9.2 6 17.2 9.8 19.5 12.03 24 14.26 alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 18 © adama science & technology university https://ejssd.astu.edu.et 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 4 8 12 16 20 24 k a ra t normalized intensities (logarithmic) a linear fit of data1_a figure 6. karat of gold versus normalized ionic intensity 4. conclusion the result of the investigation clearly shows that the purity of gold can be asserted from the integrated normalized intensity of all spectra line of gold, as well as from intensity to background ratios of ionic and atomic lines. for the non-resonant atomic emission line at 267.597 nm and ionic emission line at 226.363nm for all the gold samples, it was found that there are direct linear relationships between the karat of gold and the ionic to background and atomic to back ground ratios. the value of the ratios was found to be in direct proportion with the corresponding karat values. it was also notices that gold alloys of different origin could be identified by the type of impurity.in it. the presence of zinc impurity in one type of alloy from india and its absence from that from ethiopia is good evidence. therefore one can conclude that the method employed by the researcher could be used as an alternative and also robust method to monitor precious metals quality such as gold. acknowledgment the authors would like to acknowledge allahabad university, alemu kebede ethiop. j. sci. sustain. dev., 5 (1), 2018 19 © adama science & technology university https://ejssd.astu.edu.et india, for materials, equipment as well as expertise support they gave to him. references 1. jurado-lópez a. et.al (2006): application of energy-dispersive x-ray fluorescence to jewellery samples determining gold and silver, analytical chemistry department, marie curie building, annex, campus of rabanales, university of córdoba, córdoba, e-14071, spain. 39:1-21 2. belkov, m.v., et.al. (2010): rapid analysis of emission spectra for gold alloys, journal of applied spectroscopy, vol. 77, no. 3, 352–357. 3. jurado-lopez a., et al. (2003): chemometric approach to laser-induced breakdown analysis of gold alloys. applied spectroscopy; 57 : 349–352. 4. gornushkin i. b., et al. (2009): papers presented at the fifth international conference on laser induced breakdown spectroscopy b, 64: 1040– 1047. 5. pershin s. m. and colao f. (2005): a new approach to the quantitative elemental analy-sis of alloys by means of the laser induced breakdown spectroscopy (libs), technical physics letters: 31: 48–57 6. fesenko et.al (2005): spectral standard-free laser microanalysis of gold alloys. journal of applied spectroscopy, vol. 72, no. 3 26 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper degree of acidity related soil chemical properties and effect of lime rates on phosphorus adsorption characteristics of wayu tuka district, western oromia, ethiopia achalu chimdi ambo university, department of natural resources management, p.o box 19, ambo, ethiopia article info abstract article history: received 15 march 2022 received in revised form 11 june 2022 accepted 16 june 2022 soil acidification and phosphorus (p) deficiency are major challenges to acid sensitive crop production in most of the highlands of oromia. study was initiated to evaluate degree of acidity related soil chemical properties and impact of the application of agricultural lime (0, 3, 5, 7 and 9 t ha-1) rates on p-sorption characteristics of acidic soil. replicated representative soil samples were collected from the soil surfaces (0-20 cm) depth of the four kebeles and mixed with lime of 100 mesh size was incubated for 90 days at approximately field water holding capacity. a 90 days greenhouse incubation experiment were employed using standard laboratory procedures to evaluate effect of application of agricultural lime rates on acidity related chemical properties, p-sorption characteristics and percent increment of available p. analysis of soil chemical properties (ph, exchangeable acidity, al saturation, available and total p, soil p-sorption characteristics were evaluated before and after incubations. result of soil ph, revealed that all soils from studied sties fallen in very strongly acidic (4.63-4.89) media. values of soil exchangeable acidity, percent acid saturation and al saturation of soils ranged from 1.43-2.49cmol (+) kg-1 soil, 5.36-9.37% and 3.57-6.28%, respectively. available p before liming varied from 7.07-8.02 ppm and qualifying low range. however, due to application of lime, there was decrease of average percent total psorption of soils and ranged from 93% in the control to 57% at 9 t ha-1 lime rates. moreover, percent increment of average available p ranges from 7.2% in the control to 43.6% for 9 t ha-1 lime. the positive values of r2 values of langmuir regression equation indicated, there was strong positive relationship of increment of p availability with lime rates incubated soils. therefore, the 90 days soil-agricultural lime incubation study showed the potential capacity of agricultural lime to reduce the p-sorption by increasing available p of acidic soil of the study area. field experiment to explore the effects of lime on other acidity related soil physical and chemical properties are recommended to strength the present study. keywords: acidic soils gricultural fields lime rates p-sorption wayu tuka 1. introduction phosphorus (p) is a critical essential macronutrient for crop production and considered to be one of the key plant nutrients but its limited availability in soils is often severely restricts crop yields. acidification of soil is one of the most important soil factors affecting for successful crop production and ultimately yields. e-mail: achaluchimdi@yahoo.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.424 mostly it is the result of a complex set of processes caused by both naturally and anthropogenic activities (amede et al., 2019; dubus & becquer, 2001; hosseinpur & ghanee, 2006). from soil science and agronomic aspects, the study of sorption and desorption reactions between phosphate http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.424 achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 27 and soils is very important. phosphorus sorption is mainly studied by sorption isotherms which were historically initiated for evaluating its availability for crop uptake but have become popular for assessing the soil p mobility in environmental applications (siddique & robinson, 2003). according to birru and heluf (2003) the soil’s sorbing capacity in relation to soil properties can be rated using various indexing techniques and the relationship between the various isotherm and sorption parameters. the sorption of p in acid soils occurs mainly on surfaces of fe and al oxides and hydroxides as well as through ligand exchange on variable charge surfaces by the exchange of ohon the surface for the phosphate ion (scheme 1). there is a covalent bond between the metal ion and the phosphate ion. phosphate is considered to sorb mainly as an innersphere complex which means that the sorption takes place at specific coordination sites on the oxides or hydroxides and no water molecules are present between the surface and the phosphate anion (agbenin, 2003; birru & heluf, 2003). the p sorption is a continuous sequence of adsorption and precipitation and consists of two processes, one relatively fast, reversible adsorption process and a relatively slow, practically irreversible precipitation process (van der zee & van riemsdijk, 1998). the magnitude of p sorption highly correlated with exchangeable and extractable forms of fe and al ions in the soil solutions. currently, there is increasing awareness that soil nutrient depletion from the agroecosystem caused by soil acidification is a very wide spread problem and is an immediate crop production constraint in ethiopia. acidification of soil is one of the most important soil factors affecting for successful crop production and ultimately yield. it also limits plant growth not only because of the deficiency of major nutrients like phosphorus (p), calcium (ca) and magnesium (mg) but also due to toxicity of aluminum (al3+), manganese (mn2+), iron (fe3+) and h+ ions practice (bolan et al., 1992). it is important that soil acidity be understood in terms of its fundamental chemistry so that appropriate soil management and remediation schemes are based on sound principles rather than on empirical knowledge that may only be locally relevant. sustained production of crops on acidic soils requires addition of soil amendments. various investigators have shown that this toxic effect of acid soils constraints to crop production can be overcome through the application of lime and of superphosphate in rather large amounts (amede et al., 2019; chimdi et al., 2012). the major research intervention in solving the problems of acid soils is liming, and determining lime requirement (lr) of acid soil is one of the major research concerns(abebe, 2007). liming acidic soil may often increases crop p uptake by reducing the amounts of soluble al rather than any direct effects on p availability (curtin & syres, 2001). in the western oromia region, land use changes particularly from natural forest to grazing land and crop production under poor management practices and/or no crop rotation caused decline in soil fertility. moreover, severe erosion and land degradation from the surface soils are the major contributing factors for the soil acidification. furthermore, crop diversity and yields are declining due to pronounced influence of soil acidity on plants, because of soil acidity. as a result, most of the crops which are susceptible to soil acidity like barley, bean, and wheat are forced to be out of production in the region (chimdi et al., 2013; fite et al., 2007; paulos, 2001). currently, in most part of western oromia, the problem of soil acidity caused by al saturation in the high rainfall area has become a national issue. in line with this, several studies (chimdi, 2014; chimdi et al., 2013; wakene & heluf, 2003) have been done on soil p status, dynamics and its availability as well as on the properties, severity of soil acidity in some ethiopian scheme 1: mechanism of soil p adsorption on aloxide surface. achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 28 highlands. however, evaluation of the degree of acidity related chemical properties and impact of different lime rates on p sorption character of highly acidic soils area of the agricultural lands of wara babo migna, gara hudha, wali galte, and gute badiya kebeles of wayu tuka district are not yet studied in sufficient detail. therefore, to fill the gap, the present study was initiated to evaluate the degree of soil acidity and effect of different lime rates on p-sorption characteristics of highly acidic soil areas of the agricultural lands of the study area. such study is used for estimating the optimum amount of the agricultural lime required for a given agricultural lands and to counteract soil acidity thereby raising soil ph, soil available p and improving crop production and productivity of the study area. 2. materials and methods 2.1. description of the study area the present study was conducted in four kebeles of wayu tuka districts of east wollega zone, oromia regional state, ethiopia. gute is the administrative center of the district; it is located at a distance of 12 km from nekemte zonal capital town. the district is located 320 km from the capital city, addis ababa toward the west of the country and 10 km away from nekemte. it is bounded by sibu sire in the north and east, leka dulecha in the south, and guto gida in the west. geographically, the district is located in the western highlands of ethiopia lying between 8°56'56"n and 9°7'49"n and 36°32'38"e and 36°49'3"e. according to wayu tuka administrative office the altitude of the district ranges from 1300-3140 m.a.s.l. the study area consists of four kebeles such as wara babo migna, gara hudha, wali galte and gute badiya. location map of the study area is shown below in (figure 1). the topography of the study district is mountainous and slopping landscape. nitisols are the major soils that cover the western part of ethiopia (chimdi et al., 2012; fao, 1990). the study site soils were classified as nitisol covering large production areas, according to the fao (1990) classification legend and the main soil group of most of the east wollega zone is nitisols and the soil is acidic in reaction as cited by ethiopia.the climate of the district is classified traditionally into three main agro-climatic zones, low land, midland, and highland. the total landmass of the district, about 49.23% (14,249 hectares) is midland ‘badadaree’ while 37.665% (10,704.73 hectares) categorized as high land ‘baddaa’ and 13.16% (10,704.73 hectares) is low land ‘gammojjii’ as reported by (deresa, 2013; wtwao, 2017). the thirteen years (2006-2018) climatic data from nekemte meteorological station was recorded and the area has a unimodal rainfall pattern that extends from april to october with average annual precipitation of 2166.43 mm. maximum rain is received in june, july, and august, with a mean monthly temperature varying from 11.93-28.21°c. figure 1: location map of the study area achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 29 2.2. land uses, major vegetation types and farming system cultivated and grazing lands are the major lands used in the area. however, cultivated land is the dominant land use of the area because crop production is widely practiced through traditional subsistence farming on individuals held under rain-fed conditions. the second land use is the grazing land which is individually held by the farmers. the major crops grown in the area are coffee (coffee arabica l.), teff (eragrostis tef), maize (zea mays l.) and potato (solanum tubersoum l.) hot pepper (capsicum frutescence) and are usually produced once in a year under rainfed conditions. rapid human growth at the study area has resulted in a substantial change in declining soil fertility and most natural forest has been cleared for crop production and local fuel. intensive farming practices and the high rainfall amounts have exposed the soils of the study areas to severe erosion resulting in nutrient loss, soil acidity and overall land and natural resource degradation. as a result, most of the crops which are susceptible to soil acidity like barley, bean, and wheat are forced to be out of production in the region (fite et al., 2007). similar to most parts of the country, the economic activities of the local society of the study area are primarily a mixed farming system that involves animal husbandry and crop production. the farming system is a subsistence involving a mixing croplivestock production agricultural system. 2.3. site selection, soil sampling and preparation for the present study, four kebeles were purposely selected from the wayu tuka district as it is among the kebeles in the district where soil acidity problem has been predominantly occurred and reported by (wtwao, 2017). based on field observation, soil surveys, and data obtained from the previous studies reported by chimdi (2014) and deresa (2013), the following kebeles (wara babo migna (wbm), gara hudha (gh), wali galte (wg) and gute badiya (gb) were selected as acidic soils wayu tuka district. thus, the selected acidic soils of agricultural lands were delineated and dug on different landscape positions to collect samples from the soil surfaces (0-20 cm) depth of the four kebeles. then 2 kg composite soil sample from selected district was properly bagged, labeled and transported to laboratory for analysis of the parameters of selected soil properties (soil moisture contents, soil ph, electrical conductivity, available p, total p, soil p adsorption characteristics supported by batch type experiment and based up on their standard laboratory procedures at the nekemte soil research and holetta agricultural research centers. 2.4. design and soil incubation experiment soil incubation experiment was employed to study the effect of different lime rates on p adsorption characteristics of soils in three-way factorial combination of five rates (0, 3, 5, 7 and 9 t ha-1) of 100 mesh sizes of agricultural limes. the incubation experiment was prepared by mixing different proportions of lime rates with 1 kg of a composite of soils from acid soil of study sites was packed into 200ml polythene bag and thoroughly mixed with different rates of (0, 3, 5, 7 and 9 t/ha) of lime with replication. composite soil samples were incubated for 90 days at approximately field water holding capacity to allow for lime to react with the soils after which they were once again air-dried for laboratory p sorption studies together with the control (no lime). the soil-lime mixture was stirred every seven days to uniformly mix the lime with the soil in a clean plastic bag. each treatment was wetted and rewetted every three days regularly to maintain the field capacity at chemistry department laboratory of wollega university. agricultural lime (caco3) was offered from nekemte soil research center. its calcium carbonate equivalent was determined by acid neutralization method and found to be 92.6%. 2.5. laboratory analysis of soil samples the soil ph using (h2o) was measured potentiometrically with digital ph meter in the supernatant suspension of 1:2.5 soils to water ratio (barauah & barthakulh, 1997). the soil electrical conductivity measurement was done using conductivity meter at 250c using its standard procedures. soil available p was extracted by the bray-ii method (bray & kurtz, 1945) and the reading was quantified by using spectrophotometer at wave length of 880 ηm. soil exchangeable acidity (al+3 and h+) was determined by saturating the soil sample with 1n kcl solution and titrating with 0.02 n naoh as described by rowell (1994). from the same extract, exchangeable al was measured by titrating the solution samples with a standard solution of 0.02n hcl. soil moisture content achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 30 was done by gravimetric method and calculated as: 𝑆𝑜𝑖𝑙 𝑚𝑜𝑖𝑠𝑡𝑢𝑟𝑒 𝑐𝑜𝑛𝑡𝑒𝑛𝑡(%) = 100(𝑀𝑜𝑖𝑠𝑡 𝑠𝑜𝑖𝑙 𝑤𝑒𝑖𝑔ℎ𝑡 − 𝑂𝑣𝑒𝑛 𝑑𝑟𝑦 𝑤𝑖𝑒𝑔ℎ𝑡) ÷ 𝑂𝑣𝑒𝑛 𝑑𝑟𝑦 𝑤𝑖𝑒𝑔ℎ𝑡 … … … … …. (1) 2.6. phosphorus adsorption study of experimental soils the incubated soil with and without lime was ground and passed through 2 mm sieve. then, the airdried 2 gm of incubated experimental soils with different lime rates and the control (no lime) was tested with a stock solution of 0 and 10 mg p/l p (kh2po4). each sorption set for p was replicated three times. phosphorus sorption rate was determined by batch equilibrium methods in which soil samples was agitated with p solutions of known concentrations (graetz & nair, 2008). subsamples of soils were collected from an incubated sample prepared for the study of p-sorption. all soil samples were air-dried at ambient temperature of 25°c crush and sieve through a 2mm sieve. phosphorus as (kh2po4) was dissolved in a 0.01 m solution of cacl2 in distilled water. the cacl2 solution was used as the aqueous solvent phase to improve centrifugation and minimize cation exchange (fuhrman et al., 2004). according to the method of fernandes and coutinho (1994), to study the sorption of p by soils, 2g air-dried samples of each soil was placed in 100ml plastic bottle in order to leave free space for with 25 mlof 0.01m cacl2 in which the final volume was adjusted to 30mltwo drops of chloroform were added to suppress microbial growth (self-davis et al., 2000). at the end of equilibration period, the soil suspensions were centrifuged at 5000 rpm for 20 minutes. after centrifugation, the soil solution was filtered with a 0.45 µm membrane filter paper and the concentration of p in the clear extract was determined by ascorbic acid method. after the equilibrium, the filtered solution was taken for the measurement of the concentration of initial available p sorbed using a spectrophotometer at a wave length of 880 ηm (john, 2009). phosphorus that disappeared from the solution was considered as sorbed p which was plotted against p concentration in the solution to obtain a p sorption isotherm. the p sorption data for the soils was fitted into the following forms of langmuir equation, because linear regression was convenient and best of data-fitting process. langmuir equation: 𝐶 𝑋 = 1/k. xm + 𝐶/𝑋𝑚…………………….(2) where, c (mgl-1) was the equilibrium concentration, x (mg kg-1) was the amount of p adsorbed per unit mass of adsorbent, k (l mg-1) was a constant related to the energy of sorption, and xm (mg kg-1) was p sorption maximum. where, 𝑋 = 𝐶0𝑉0 − 𝐶𝑓𝑉𝑓 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑠𝑜𝑖𝑙 (𝐾𝑔) … … … (3) where, co was the initial concentration, cf is final concentration and v is the volume of solution. the linear form of equation (2) was obtained by plotting the equilibrium concentration of phosphate (c) against the amount of phosphate adsorbed (x) and the slope of the graph equal to 1/xm and the intercept of the graph is equal to 1/k.xm. but, k was easily determined by dividing the slope by intercept. 2.7. analysis of statistical data data generated from analysis and testing linearity between various soil parameters such as soil ph, soil electrical conductivity and soil moisture contents, available p, and sorption patterns were subjected to correlation and regression analysis using spss statistical software . 3. results and discussion 3.1. soil ph, electrical conductivity and moisture content of experimental soil in the present study, results of standard measurement of soil ph using h2o before the application of agricultural lime are presented in table 1. as revealed from the result of soil ph data, all of the soils samples collected from the four kebeles were fallen in very strongly acidic media. however, relatively higher (4.89) soil ph-h2o value was recorded in soils of the agricultural fields of gute badiya kebele while lower value (4.63) was recorded in soils of gara hudha kebele. as per the rating indicated by jones (2003), the soil ph values of the agricultural lands of all the sites were very strongly acidic. this may be due to the depletion of basic cations (k, ca and mg) from the surface soil caused by crop harvest, deforestation and continuous cultivations exposes the soils to sever acidity of the agricultural lands of the studied district. electrical conductivity (ec) is the conductance of a soil solution filling the space between two metal surfaces. in the present study, all of the soils collected from the four achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 31 kebeles were recorded small electrical conductivity values of about 0.03 ms/cm at wara babo migna and a maximum of 1.23 ms/cm was recorded in the soils of wali galte kebele. all of the soil samples have an electrical conductivity values ranging from 0.03-1.23 ms/cm and lies at lower limit of saline soils. this implies that, the soil samples of the four kebeles are nonsaline soils with no salinity problem. according to (azeez & van averbeke, 2012), lower soil ph implies higher soil acidity which indicates higher concentration of h+ in the soils solution. the high soil acidity at low ph due to higher concentration of h+ can appear in varying amount in the soil solution may affect the level of electrical conductivity as a result aggravated to soil acidification .thus, higher concentration of h+ in the soil show a higher values of electrical conductivity. the soil moisture content of the experimental soils was given in table 1. information on soil’s moisture content is useful for assessing plant water uptake and consumptive use, depth of water infiltration into soil, water storage capacity of soil, rate and quantity of water movement, deep drainage and leaching of chemicals, soil-strength and soil compact-ability (foth, 1990). however, soil moisture content can be high or low depending on the presence or absence of rain fall. when comparison are made among the moisture contents of the experimental soils of the present studied kebeles, their moisture content vary from one kebele to another, and it was lowest value 11% in soils of gute badiya kebele to the relatively high 18.76% in soils of wara babo migna (table 1). the variation in percent moisture content of the soils of different kebeles may be due to differences in their sand, silt and clay fractions and its negative effects with soil respiration. 3.2. status of soil available phosphorus and total phosphorus before lime application the soil p may enter the soil solution by dissolution of inorganic p associated with the soil’s solid phase. result of the present finding indicated, available p content before lime application of the four kebeles varied from 7.91-8.82 ppm (figure 2). the value was lower in all of the four kebeles. the lower available p content in soils of the present studies sites are related the high degree of pfixation with fe and al and continuous application of mineral p fertilizer sources as indicated by paulos (1996). the biogeochemistry of p in soils is complicated. most acidic soils are also extremely p deficient, a problem usually exacerbated by the presence of active fe and al oxides. as per the rating suggested by jones (2003), available p of the studied district was qualifyin low range, however, numerically better in soils of gute badiya kebele and lower in soils of wali galte kebele. the distribution of total p content followed a similar pattern to available p distributions and range from 679 to 687 mg kg-1. as per the rating of landon (1991), medium total p content was observed in the entire soil of studied district, though numerically better in in soil of gute badiya kebele (figure 3). result of this study is consistent with chimdi et al. (2013) and wakene and heluf (2003), findings who observed that variations in available p contents in soils are related with the intensity of soil disturbance, high degree of pfixation with fe and al ions in the soils. similarly tekalign and haque (1987) and dawit et al. (2002) reported soil organic matter as the main source of available p and the availability of p in most soils of ethiopia decline by the impacts of p-fixation, abundant crop harvest, continuous cultivations and erosion. 3.3 exchangeable acidity and percent acid and aluminum saturation soil exchangeable acidity, percent acid saturation (pas), and percent al saturation show some variations among the four kebeles of wayu tuka district and ranged from 1.43 to 2.49cmol (+) kg-1 soil, 5.36 to 9.37% and 3.57 to 6.28%, respectively (figure 3). these soil exchange properties were affected by soil acidity. this may be due to inherited from acidic parent material, application of ammonium fertilizers, wet climate, high table 1: mean values of ph (h2o), ec (ms/cm) and moisture content (%) of experimental soils location/districts ph (h2o) ec (ms/cm) moisture content (%) gara hudha 4.63 0.05 15.39 wara babo migna 4.68 0.03 18.76 wali galte 4.75 1.23 14.15 gute badiya 4.89 0.15 11.01 achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 32 figure 1: mean values of available and total phosphorus pas= percent acid saturation; pals=percent of aluminum saturation figure 2: mean values of acidity related chemical properties of soil of the study area rainfall and removal of basic elements through the harvest of high yielding crops. the recorded values of exchangeable acidity indicated the ease to manage the acidity problem of soils. mean values of acidity related soil chemical properties of the study sites were shown below in (figure 3). the values of soil exchangeable acidity, percent acid saturation and percent al saturation levels were higher in soils with low ph in gara hudha than the reaming sites. soil exchangeable acid, percent acid saturation, and percent al saturation follow the trend of soil ph, as soil ph decreases the values of soil exchangeable acid, percent acid saturation, and percent al saturation increasing in the soils. this might be due to uses of acid forming fertilizers as source of n and p (urea and diammonium phosphate) for crop production. the value of percent al saturation ranged from 3.57 to 6.28%. relatively high value of percent al saturation was recorded in soil of gara hudha kebele. hence, to reverse the adverse effects of soil acidity and make the soils permissible for crop production, liming and organic materials application was suggested by fite et al. (2007) and chimdi et al. (2012). in general, strongly acidic soils could be managed by using lime, whereas moderately acidic soil by growing acid-tolerant crop varieties in the study area. 3.4. effect of lime rates on available-p and percent total p-sorption of soil after incubation the term sorption was described by mcbride (1994) as a continuous process that ranges from adsorption to precipitation reactions. the soil psorption isotherms are widely used to describe p sorption desorption characteristics in soils and to predict the risk of p loss to 7.91 8.02 7.78 8.82 679 683 681 686 gara hudha wara babo migna wali galte gute badiya a v . p (p p m ) a n d t p (m g /k g ) location of study sites av. p(ppm) tp (mg kg-1) 9.37 9.09 8.68 5.36 6.28 6.08 5.73 3.57 4.63 4.68 4.75 4.89 gara hudha wara babo migna wali galte gute badiya location of study sites pas pals ph(h2o) achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 33 fresh water. liming rose soil ph available p, while it reduced exchangeable al and fe and also p sorption. this is mainly, because of the likely displacement of al3+, h+ and fe3+ ions by ca2+ ions. this also led to a decrease of percent p adsorption of soils. due to the application of the different rates of the agricultural lime, results of the present study revealed the increment of available p and decease of the percent total p-adsorption characteristics of the soils, and shown in (figures 4 and 5). figure 4: effect of lime rates on percent total p sorption of soils. table 2: regression equations of extent of p sorption as affected by lime application rate. sites regression equation r2 wbm y= -5.38x +96.73 0.91 gb y= -3.61x +90.88 0.85 wg y= -4.53x +96.04 0.92 gh y= -3.39x +97.95 0.88 x=lime rates (t ha-1); y= total p-sorption (%) wbm= wara babo migna, gb= gute badiya; wg= wali galte; gh=gara hudha the r2 values of the regression equation of the experimental soils were relatively high and ranges from 0.85-0.92, where the lower and the higher r2 value were respectively recorded at gute badiya and wali galte kebeles. the positive values of r2 obtained from the regression equation under the study sites of each districts indicated that there was strong negative positive relationship of the percent total p sorption with the incubation of soils with different application of the lime rates (figure 5). liming of acidic soils could increase soil ph, which enhances the release of phosphate ions fixed by al3+, h+ and fe3+ ions into the soil solution and likely displacement of al 3+, h+ and fe 3+ ions by ca 2+ ions it contains. moreover, the increment of available p content of the soils collected from each kebele with increasing application lime rate may be attributed to increasing ph due to liming that could release the unavailable p which was previously fixed with al and fe at low soil ph condition. therefore, agricultural liming material added to soil is beneficial to acid soil and enhances the p availability to the soils. liming and thus raising the ph of acidic soil generally provide more favorable environments for microbial activities and possibly results in net mineralization of soil organic p (lu et al., 2000). figure 5: effects of lime rates on the p-availability of soils table 3: regression equations of the extent of p availability as affected by lime application rate. sites regression equation r2 wbm y= 5.47x +3.25 0.95 gb y= 3.61x +0.42 0.85 wg y= 4.53x +3.96 0.92 gh y= 3.62x +1.80 0.87 x = lime rates (t ha-1); y=increment of p availability wbm= wara babo migna, gb= gute badiya; wg= wali galte; gh=gara hudha 0 10 20 30 40 50 60 0 3 5 7 9 % i n cr e m e n t o f a v a il a b le p d u e t o li m e in g lime rates(t ha-1) wbm gb wg gh 0 10 20 30 40 50 60 70 80 90 100 0 3 5 7 9 t o ta l p s o rp ti o n ( % ) lime rates (t ha-1) wbm gb wg gh achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 34 the r2 values of the langmuir regression equation of the experimental soils were relatively high and ranged from 0.85-0.95, where the lower and the higher r2 value were respectively recorded at gute badiya and wara babo migna kebeles. the positive values of r2 obtained from the regression equation under the study sites of each kebele indicated that there was strong positive relationship of the increment of p availability with the incubation of soils with different application of the lime rates (figure 4). the values of r2 of langmuir regression equations indicated that, sorption behavior was described by the linearized langmuir sorption model with regression coefficient (r2>0.85) observed for all the four studied kebeles. the soils differed relatively in sorption characteristics with different studied kebeles. it indicates that higher values of r2 more fit the models. the goodness of fit of the model was ascertained by looking at the r2 values. all the plots were highly correlated with r2 values ≥ 0.85 indicating apparent high conformity of the adsorption data to the langmuir model. the average percent of total psorption of the agricultural lands of the four kebeles decreased from 93% in the control (no lime) to 57% at lime rate of 9 t ha-1 (figure 6). on the other hand, percent increment of average available p of the soils of the agricultural lands was from 7.2% in the control (no lime) to 43.6% for the lime rate of 9 t ha-1. due to the application of different rates of the agricultural lime, when the percent increment of available p of soils of all the studied soils increased with increasing lime rate may be attributed to increasing ph due to liming that could release the unavailable p which was previously fixed with al and fe at low soil ph condition. liming and thus raising the ph of acidic soil across the agricultural lands of the four kebeles generally provide more favorable environments for microbial activities and possibly results in net decrease in total percent p sorption of the soils. when comparisons of total p sorption patterns and percent increment of available p made among the four kebeles are made for the lime rate of 9 t ha-1 there were high percent promotions of available p and low soil p fixation in wara babo migna kebele and the reverse was true in soils of gara hudha kebele. the reason for these inverse relationships between the increment of percent available p and decrease of percent total p sorption patterns were due to positive and negative effects of exchangeable bases and acids in the soil solutions, respectively. that is, as the rates of agricultural lime applied to the soil increased the concentration of exchangeable bases like ca2+ in the soil solution increases thereby decreasing the percent total p sorption patterns and exchangeable acid (al and h) ions from the soil exchange complex. figure 3: effects of lime rates on the mean percent total psorption of experimental soils. achalu chimdi. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 35 4. conclusion soil p is an essential plant nutrient, and its deficiency in soils severely restricts crop yields. tropical and subtropical soils are predominantly acidic and often extremely deficient in p. results of this study revealed that, all of the soils samples collected from the four kebeles (gara hudha, wali galte, wara babo migna and gute badiya) were fallen in very strongly acidic (4.63-4.89) media and have an electrical conductivity values ranging from 0.03-1.23 ms/cm. the available p content before lime application of the four kebeles varied from 7.91-8.82 ppm which was qualifying the low range. however, due to the application of the different rates of the agricultural lime, revealed the increment and decease of the available p and p-sorption patterns of the soils, respectively. hence, the application of agricultural lime into soil have positive effect to alleviate the inherent acidity of the soils through its ability to neutralize the soil acidity thereby increasing soil ph and the concentration of the basic nutrient such as available p in the soil solutions for plant uptakes. however, further research work may be recommended to validate the findings of the present greenhouse incubation study and for more intensive inclusions of the soil chemical, physical and mineralogical properties and reliable information of the effect of soil properties in predicting soil p sorption patterns at different acidic soils areas is suggested in the field. acknowledgements the author would like to thank wollega university and holleta agricultural research center for their logistic and material support during research work and laboratory sample analysis. reference abebe, m. 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(2017). wayutukawereda agricultural office. wayutukawereda, east wollega zone, oromia. 54 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9(1), 2022 journal home page: www.ejssd.astu.edu.et astu research paper evaluation and registration of the newly introduced supersonic alfalfa (medicago sativa l.) variety in ethiopia gezahagn kebede1, fekede feyissa2, solomon mengistu1, mulisa faji1, kedir mohammed1, mesfin dejene1, gezahegn mengistu1, diriba geleti2, getnet assefa3, aklilu mekasha4, mezgeb workiye5, tekleyohannes berhanu6, berhanu megersa7, aman getiso8, edao shanku8, fromsa ijara8, diribi mijena8, esubalew shitaneh9 and habtie arega9 1holetta agricultural research center, p. o. box, 31, holetta, ethiopia 2ethiopian institute of agricultural research, p. o. box, 2003, addis ababa, ethiopia 3international livestock research institute, p. o. box, 5689, addis ababa, ethiopia 4melkassa agricultural research center, p. o. box, 436, melkassa, ethiopia 5kulumsa agricultural research center, p. o. box, 489, assela, ethiopia 6debre zeit agricultural research center, p. o. box, 32, debre zeit, ethiopia 7werer agricultural research center, p.o. box 2003, addis ababa, ethiopia 8wondo-genet agricultural research center, p. o. box, 198, wondo-genet, ethiopia 9pawe agricultural research center, p. o. box, 25, pawe, ethiopia article info abstract article history: received 30 december 2021 received in revised form 12 march 2022 accepted 26 march 2022 alfalfa (medicago sativa l.) is one of the most important perennial forage legume recommended for livestock feed due to its better yield and nutritional quality. so the introduced supersonic alfalfa variety was evaluated with the standard check variety (alfalfa-1086) at holetta, debrezeit, kulumsa, wondo-genet, werer, and pawe locations aimed to assess forage biomass yield, chemical composition, and tolerance to major pests and diseases during the main cropping season of 2018 under supplementary irrigation. the result indicated that the introduced supersonic alfalfa variety gave a higher (p<0.05) plant height and dry matter yield than the standard check variety at each location and combined across locations. moreover, the plant height and dry matter yield of alfalfa varieties varied significantly (p<0.05) across locations. the introduced supersonic alfalfa variety was consistently superior in dry matter yield than the standard check variety which implied better stability under diverse environmental conditions. however, the dry matter yield varied across locations due to the differential response of the varieties for the test locations. the introduced supersonic alfalfa variety had 12.9, 11.6, and 7.7% dry matter yield, digestible yield, and crude protein yield advantages over the standard check variety, respectively. the nutritive values of supersonic alfalfa were slightly lower in ash, crude protein, digestibility and relative feed value and higher in fiber contents than the standard check variety. based on the overall performances, the introduced variety was verified with the same standard check variety during the main cropping season of 2020 under supplementary irrigation. due to its better yield performance, and pest and disease reaction, the national variety releasing committee approved supersonic alfalfa variety in 2021 to be cultivated in low to high altitude areas ranging from 750 to 2400 meters above sea level, which have an annual rainfall ranging from 800 to 1200 mm. keywords: dry matter yield nutritive value supersonic alfalfa variety registration variety release corresponding author, e-mail: gezk2007@yahoo.co.uk https://doi.org/10.20372/ejssdastu:v9.i1.2022.407 http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i1.2022.407 gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 55 1. introduction despite the large livestock population in ethiopia, the sector contributed below its potential due to various constraints (gebremedhin et al., 2004). feed shortage in terms of both quantity and quality is the leading problem affecting the livestock productivity in ethiopia (adugna, 2007; fekede et al., 2015a; fekede et al., 2015b). livestock feed resources in ethiopia are mainly natural pasture, crop residues, improved pastures, forage crops, and agro-industrial by-products (alemayehu, 2004). the contribution of these feed resources, however, depends on the agro-ecology, the types of crop produced, accessibility, and production system. traditional livestock production system mainly depends upon poor pasturelands and crop residues, which are usually inadequate to support reasonable livestock production (tsige, 2000). during the latter part of the dry season, livestock feed is normally in short supply and is of poor quality. residues from cereals are the main source of forage but these are low in protein and have poor digestibility (getu, 2019). the production of adequate quantities of good quality dry season forages to supplement crop residues and pasture roughages is the only way to economically overcome the dry season feed constraints have been affecting livestock production. thus, different forage crops were screened at both accessions and species level, and the promising genotypes were promoted for production (getnet and gezahagn, 2012). a wide range of annual and perennial forage species were evaluated in areas which have an altitude ranging from 600-3000 meters above sea level, and varieties of promising species had been selected and recommended for high, medium, and low altitudes in ethiopia. these selected forage species are well adapted to the different agro-ecologies and gave high yield, and have better nutritional quality as compared to natural pasture (getnet et al., 2012). however, the adoption of cultivated forage crops is very low due to various reasons (agajie et al., 2016). among the different forage crops recommended for various agro-ecological zones of ethiopia, alfalfa (medicago sativa l.) is one of the most valuable forage species due to its high yield and nutritional value, and better adaptability under diverse environmental conditions. the species is also grown worldwide due to its better productivity and herbage quality (turan et al., 2009). it is commonly known as the “queen of forages” due to its ability to consistently produce better forage yield and quality (kamalak et al., 2005). moreover, it is used to improve vegetation cover, prevent grasslands degradation, and contribute to agriculture and livestock sustainability (chen et al., 2012). when associated with other grass the grassland production increases, the nutritional value improves and feed costs decrease compared to balanced feed (zaragoza et al., 2009). variability for agronomic and morphological traits of alfalfa is frequently used in a breeding program for developing cultivars with high forage yields (jullier et al., 2000; radović et al., 2001; radović et al., 2009). depending on soil and environment conditions, alfalfa achieves fresh and dry matter yields which ranged from 50 to 100 t/ha and 12 to 19 t/ha, respectively (katić, 2000; nešić et al., 2005; stanisavljević et al., 2006). ruminants fed on alfalfa have higher nutrient intake and digestibility than when fed on other forage legumes (frame, 2005). the alfalfa forages are characterized by a high content of crude protein (dinić et al., 2005; marković et al., 2007a), well balanced to an amino acid. it is enriched with important vitamins, and various microelements which are essential for the normal growth and development of animals (marković et al., 2007b). to improve the quantity and quality of livestock feed, it is better to identify and cultivate the promising alfalfa variety that has better biomass yield and nutritional quality. therefore, this study was aimed to evaluate the forage yield performance, nutritive value, agro-ecological adaptation, disease and pest reaction, and management recommendations of the recently registered supersonic alfalfa variety in ethiopia. 2. methodology 2.1. study areas the national variety trial (nvt) was conducted at on-stations of holetta, debre-zeit, kulumsa, wondogenet, werer, and pawe agricultural research centers during the main cropping season of 2018 under supplementary irrigation. moreover, the variety verification trial (vvt) was done at holetta, debrezeit, melkassa, kulumsa and wondo-genet agricultural research centers during the main cropping season of 2020 under supplementary irrigation. the trial sites' geographical position and physicochemical properties of the soil are summarized in table 1. gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 56 table 1: description of the test locations for geographical position and physicochemical properties of soils parameters holetta debre-zeit kulumsa wondo-genet werer pawe melkassa latitude 9°00'n 8°44'n 08°05’n 07°19’n 9°16’n 11°19’n 8°24’n longitude 38°30'e 38°38'e 39°10’e 38°38’e 40°9’e 36°24’e 39°19’e altitude (m.a.s.l.) 2400 1850 2200 1780 750 1120 1550 distance from addis ababa (km) 29 48 167 270 280 572 117 annual rainfall (mm) 1044 850 820 1372 590 1588 763 daily minimum temperature (°c) 6.2 8.9 10.5 11.0 26.7 17.1 14.0 daily maximum temperature (°c) 21.2 28.3 22.8 26.0 40.8 32.7 28.4 soil type nitosol alfisol luvisol luvisol vertisol nitosol andosol textural class clay loam clay loam clay loam clay loam clay loam ph(1:1 h2o) 5.24 7.26 6.0 6.4 7.5 4.72 7.6 total organic matter (%) 1.80 2.83 5.50 1.8 1.9 3.34 12 total nitrogen (%) 0.17 0.22 0.25 0.2 0.1 0.16 1.0 available phosphorus (ppm) 4.55 10.84 7.5 9.0 26.3 5.39 20.29 references for soil properties gezahagn et al., 2020 habtie et al., 2020 gezahagn et al., 2020 m.a.s.l. = meters above sea level; ph = power of hydrogen; ppm = parts per million 2.2. experimental design and treatments the supersonic alfalfa variety was introduced from australia and evaluated for yield and nutritional qualities under diverse environmental conditions. the experiment was laid out in randomized complete block design (rcbd) with three replications per variety. the introduced supersonic alfalfa variety was sown with the standard check variety (alfalfa-1086) on well-prepared seedbeds in rows of 20 cm apart using a seed rate of 20 kg/ha (gezahagn et al., 2021). diammonium phosphate (dap) fertilizer at the rate of 100 kg/ha was uniformly applied for both varieties at sowing (gezahagn et al., 2021). based on its better adaptability, yield, and tolerance to pest and disease performances in nvt, the variety was selected for a variety verification trial (vvt). accordingly, both varieties (supersonic alfalfa and alfalfa-1086) were sown in rows of 20 cm apart on a plot size of 10 m by 10 m with a seeding rate of 20 kg/ha. the recommended rate of dap fertilizer was also uniformly applied for both varieties in the vvt experiment at sowing. all recommended management practices (such as weeding, harvesting etc.,) were applied for both varieties during the growing season. 2.3. data collection and measurements measurements on plant height were taken randomly from five plants in each plot using a height measuring meter from the ground level to the tip of the plant. for the determination of biomass yield, varieties were harvested at the 50% flowering stage (gezahagn et al., 2021). the weight of the total fresh biomass yield was recorded from each plot in the field and the estimated 500 g of their representative samples were taken from each plot to the laboratory. the estimated 500 g sample taken from each plot was weighed to know the total sample fresh weight using sensitive table balance and then oven-dried for 72 hours at a temperature of 65oc to determine the dry matter yield. the crude protein yield was calculated by multiplying crude protein content with total dry matter yield and then dividing by 100% (gezahagn et al., 2021). the digestible yield was determined by multiplying ivdmd with total dry matter yield and then dividing by 100% (gezahagn et al., 2021). gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 57 2.4. laboratory analysis the varieties were harvested at the 50% flowering stage and submitted for laboratory analysis. the ovendried samples, at a temperature of 65°c for 72 hours, were used for laboratory analysis to determine the chemical composition and in-vitro dry matter digestibility of the varieties. the dried samples were then ground to pass a 1-mm sieve and used for laboratory analysis. the analysis was made for the different nutritional parameters. total ash content was determined by oven drying the samples at 105°c overnight and by combusting the samples in a muffle furnace at 550°c for 6 hours (aoac, 1990). nitrogen (n) content was determined following the microkjeldahl digestion, distillation, and titration procedures (aoac, 1995), and the crude protein (cp) content was estimated by multiplying the n content by 6.25. the structural plant constituents like neutral detergent fiber (ndf), acid detergent fiber (adf), and acid detergent lignin (adl) were determined according to van soest and robertson procedure (1985). the in-vitro dry matter digestibility (ivdmd) was determined according to the tilley and terry procedure (1963). 2.5. relative feed value relative feed value (rfv) is an index used for legumes based on potential intake and fiber digestibility (undersander and moore, 2002). the index used to rank feeds relative to the typical nutritive value of full bloom alfalfa hay, containing 41% adf and 53% ndf on a dm basis, and having an rfv of 100, which is considered to be a standard score. this index is widely used to compare the potential of two or more forages based on energy intake (schroeder, 2013). accordingly, forages with rfv greater than 100 are considered to have better quality than full bloom alfalfa hay and those with rfv lower than 100 are regarded as of lower quality than full bloom alfalfa. such a single parameter is considered to be of useful practical significance in forage pricing and marketing (uttam et al., 2010; schroeder, 2013) and calculated as follow: rfv = (ddm %dm) * (dmi % bw) / 1.29 (uttam et al., 2010), where, ddm (digestible dry matter) and dmi (dry matter intake potential as % of body weight) were calculated from adf and ndf, respectively as follow: ddm (% dm) = 88.9 (0.779 * % adf) dmi (% bw) = 120 / (% ndf). 2.6. statistical analysis differences among varieties were tested using analysis of variance procedures of the sas general linear model to compare treatment means (sas, 2002) and the following model was used: yijk = µ + gi + ej + (ge)ij + bk(j) + eijk; where, yijk = measured response of genotype i in block k of environment j; µ = grand mean; ti = effect of genotype i; ej = effect of environment j; (ge)ij = genotype and environment interaction; bk(j) = effect of block k in environment j; eijk = random error effect of genotype i in block k of environment j. the least significant difference (lsd) was used for the comparison of means at a 5% significance level. 3. results and discussion 3.1. varietal evaluation the seed of supersonic alfalfa variety was introduced from australia by harvest general trading private limited company under license from the ministry of agriculture. the variety was introduced to ethiopia in 2018. the introduced supersonic alfalfa variety was sown with the standard check variety (alfalfa-1086) to conduct the national variety trial (nvt) at holetta, debre-zeit, kulumsa, wondo-genet, werer, and pawe agricultural research centers during the main cropping season of 2018 under supplementary irrigation. the plots were uniformly irrigated at field capacity every 15 days during the dry season of the year. the experiment was laid out in rcbd design replicated three times. the introduced alfalfa variety and the standard check variety were sown on well-prepared seedbeds in rows of 20 cm apart using a seed rate of 20 kg per hectare. diammonium phosphate (dap) fertilizer was applied at the rate of 100 kg per hectare at planting at each location (gezahagn et al., 2017). plots were hand-weeded twice per year. based on the overall performances, the introduced supersonic alfalfa variety was promoted to vvt with the same standard check variety (alfalfa1086) at holetta, debre-zeit, melkassa, kulumsa, and wondo-genet agricultural research centers during the main cropping season of 2020. the varieties were planted in rows 20 cm apart on a plot size of 10 m by 10 m with a seeding rate of 20 kg/ha. at sowing, dap fertilizer at the rate of 100 kg/ha was uniformly applied gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 58 on the plots at each location. other recommended management practices were also applied. the national variety releasing committee (nvrc) evaluated the varieties at field conditions in october 2020 and based on their evaluation result, supersonic alfalfa variety was registered in april 2021 to be utilized by end-users. the mean plant height of alfalfa varieties tested across locations varied significantly (p<0.05) as indicated in table 2. the result showed that the introduced supersonic alfalfa variety gave significantly (p<0.05) a higher mean plant height than the standard check variety at each testing location and combined across locations indicating its better adaptability and stability under diverse environmental conditions. the supersonic alfalfa variety gave the highest plant height at debre-zeit followed by holetta, werer, kulumsa, and pawe while the lowest plant height was recorded at the wondo-genet site. similarly, the mean plant height recorded from both varieties was the highest at debrezeit followed by werer, holetta, kulumsa, and pawe while at wondo-genet the lowest plant height was recorded. the plant height of the supersonic alfalfa variety in the present study was higher than the value reported for the same variety in pakistan (nasratullah et al., 2018). variations in plant height of alfalfa varieties were also reported (gezahagn et al., 2017; nasratullah et al., 2018; denbela and sintayehu, 2021; tessema et al., 2021). in addition to genetic variability, soil fertility and environmental conditions could also contribute to the difference in plant height. generally, genetic variation, the response of genotypes to environmental factors, and their interactions are the major reasons for plant height differences in alfalfa (gezahagn et al., 2017). 3.2. agro-morphological characteristics the registered supersonic alfalfa variety is the perennial herbaceous forage legume characterized by its agro-morphological characteristics. the maximum plant height at the forage harvesting stage (50% flowering) is ranged from 45 to 95 cm. the registered supersonic alfalfa variety reaches for forage harvesting within 70 to 90 days after sowing. the leaf to stem ratio of the registered supersonic alfalfa variety is 1.10. the registered variety has better ash, crude protein, and invitro dry matter digestibility while relatively lower fiber (ndf, adf, and adl) contents. the dry matter yield of the registered variety per cut ranged from 2 to 5 t/ha at the forage harvesting stage. moreover, the crude protein and digestible yields of the registered variety ranged from 0.4 to 1.0 t/ha and 1.2 to 3.0 t/ha, respectively. the variety adapted to a wide range of altitudes ranging from 750-2400 m.a.s.l., which have an annual rainfall ranging from 800-1200 mm. the registered variety has good performance under nitosol and clay loam soil types. the varieties should be planted with a seeding rate of 10-20 kg/ha at 20 cm row spacing in early june. at planting, dap fertilizer at a rate of 100 kg/ha should be applied for better establishment (gezahagn et al., 2017). a summary of agronomical and morphological characteristics of the registered supersonic alfalfa variety is presented in table 3. table 2: average plant height (cm) of alfalfa varieties tested across locations in 2018 cropping season location variety location mean lsd p-value supersonic alfalfa-1086 (sc) holetta 90.2a 79.9b 85.0b 3.8132 0.0074 debre-zeit 94.8a 85.7b 90.2a 3.4033 0.0074 kulumsa 85.5a 74.2b 79.8c 4.2355 0.0074 wondo-genet 42.0a 38.0b 40.0e 1.4905 0.0074 werer 88.5a 85.3b 86.9ab 1.1800 0.0074 pawe 65.3a 61.7b 63.5d 1.3539 0.0076 variety mean 77.7a 70.8b 74.2 1.9487 <.0001 means with different superscript letter/s within a row for variety at each location, within a row for variety mean, and within the column for location mean varied significantly at 0.05; sc = standard check; lsd = least significant difference. gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 59 table 3: agro-morphological and fodder quality description of the registered supersonic alfalfa variety characteristics supersonic alfalfa species medicago sativa variety supersonic adaptation wide range of environments altitude (m.a.s.l.) 750 – 2400 rainfall (mm) 800 – 1200 soil type nitosol and clay loam seeding rate (kg/ha) 10 – 20 spacing inter-row (cm) 20 planting date early june fertilizer rate (kg/ha) p2o5 46 kg/ha at planting n 18 kg/ha at planting plant height at forage harvest (cm) 45 – 95 days to forage harvesting (50% flowering) 70 – 90 leaf to stem ratio 1.10 yield per cut (t/ha) forage dry matter: 2 – 5 cp yield 0.4 – 1.0 digestible yield 1.2 – 3.0 fodder quality (%) ash 14.28 cp 19.87 ndf 48.84 adf 37.36 adl 7.08 ivdmd 60.61 year of release 2021 breeder/maintainer harvest general trading private limited company /harc/eiar dap = diammonium phosphate; cp = crude protein; ndf = neutral detergent fiber; adf = acid detergent fiber; adl = acid detergent lignin; ivdmd = in-vitro dry matter digestibility; harc = holetta agricultural research center; eiar = ethiopian institute of agricultural research. 3.3. yield performance the mean dry matter yield of alfalfa varieties significantly (p<0.05) varied across the tested environments is indicated in table 4. the result showed that supersonic alfalfa variety gave higher dry matter yield (p<0.05) than the alfalfa1086 variety used as a standard check at each location and combined over locations. the dry matter yield of supersonic alfalfa variety ranged from 2.7 to 4.9 t/ha with the mean of 3.5 t/ha per cut across the test locations. the highest mean dry matter yield was recorded at werer followed by kulumsa, and debre-zeit locations, while the lowest yield was obtained from wondo-genet location with the yield advantages of 96, 68, and 56%, respectively when compared to wondo-genet location. the dry matter yield of alfalfa varieties also varied (p<0.05) across the test locations. accordingly, alfalfa varieties produced the highest dry matter yield at werer followed by debrezeit, kulumsa, and pawe while the lowest dry matter yield was obtained from holetta and wondo-genet locations. the difference in dry matter yield could be due to variations in soil fertility, weather conditions, and the genetic difference between the tested varieties. the mean dry matter yield of the supersonic alfalfa variety in the present study was slightly lower than the value reported for the same variety in pakistan (nasratullah et al., 2018). this is might be due to differences in soil, weather, and management conditions. the stage of maturity, soil fertility, climatic conditions, and cultivar differences are the main factors gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 60 affecting alfalfa yield and quality (stancheva et al., 2008). the importance of alfalfa in world agriculture can be attributed to several variable morphological and physiological characteristics that contribute to its high and stable yield of nutritious herbage (radović et al., 1996). its economic significance is based on the high potential for production of biomass, over 80 t/ha of green and close to 20 t/ha of dry matter yield (radović et al., 2004; nešić et al., 2005). the rank of the varieties for dry matter yield didn’t change across the test locations indicating the occurrence of non-cross-over interaction of the varieties for this trait due to their high stability performances under diverse environments (figure 1). however, the dry matter yield fluctuates across locations due to the differential response of the varieties for the test environments. the advantages of supersonic alfalfa variety over the standard check variety in terms of dry matter, crude protein, and digestible yields are indicated in table 5. the result showed that the introduced supersonic alfalfa variety had advantages of dry matter yield, crude protein yield, and in-vitro dry matter digestibility yield over the standard check variety. the introduced supersonic alfalfa variety had about 12.9% dry matter yield, 7.7% crude protein yield, and 11.6% digestible yield advantages over the standard check variety. the introduced supersonic alfalfa variety had better dry matter yield, crude protein yield, and in-vitro dry matter digestibility yield than the standard check variety. the differences in cp and ivdmd yields were due to variation in dry matter yield between the two alfalfa varieties. the introduced supersonic alfalfa variety has better yield and quality and as a result, it can contribute a lot by fulfilling the nutrition shortfall thereby improving the livestock production and productivity in the country. table 4: average dry matter yield (t/ha) of alfalfa varieties tested across locations in 2018 cropping season location variety location mean lsd p-value supersonic alfalfa-1086 (sc) holetta 2.7a 2.2b 2.4c 0.3603 0.0193 debre-zeit 3.9a 3.8b 3.9b 0.0625 0.0192 kulumsa 4.2a 3.5b 3.8b 0.4471 0.0213 wondo-genet 2.5a 2.3b 2.4c 0.0994 0.0202 werer 4.9a 4.3b 4.6a 0.3726 0.0196 pawe 2.7a 2.6b 2.7c 0.0872 0.0170 variety mean 3.5a 3.1b 3.3 0.1560 0.0002 means with different superscript letters within a row for variety at each location, within a row for variety mean, and within the column for location mean varied significantly at 0.05; sc = standard check; lsd = least significant difference. figure 1: genotype by location interaction for dry matter yield gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 61 table 5: dry matter, crude protein, and in-vitro dry matter digestibility yield advantage of supersonic alfalfa variety over the standard check variety parameters variety supersonic alfalfa-1086 (sc) dmy 3.5 3.1 % increase in dmy 12.9 cp yield 0.70 0.65 % increase in cp yield 7.7 ivdmd yield 2.12 1.90 % increase in ivdmd yield 11.6 dmy = dry matter yield; cp = crude protein; ivdmd = in-vitro dry matter digestibility; sc = standard check. 3.4. quality attributes the chemical composition and in-vitro dry matter digestibility of alfalfa varieties are presented in table 6. the result indicated that the introduced supersonic alfalfa variety had slightly lower in ash, crude protein, in-vitro dry matter digestibility, and relative feed value while relatively higher fiber (ndf, adf, and adl) contents than the standard check variety. the ash content of the supersonic alfalfa variety in the current study was slightly higher than the value reported for the same variety in pakistan while the reverse is true for cp content (nasratullah et al., 2018). a nutritional quality difference between alfalfa cultivars was not also significant in different studies (julier et al., 2000; radović et al., 2004). the main effect on alfalfa forage quality belongs to the plant stage. the decline in feed quality is associated primarily with a decrease in crude protein content and an increase in fibrous constituents of the stem in the matured plant. the decline in alfalfa forage quality with advancing maturity was reported (marković et al., 2008). the slightly lower in ash, cp, ivdmd and rfv and higher fiber (ndf, adf, and adl) contents in the introduced supersonic alfalfa variety than standard check variety might be due to differences in leaf to stem ratio. because, leafy varieties have better ash, cp, and digestibility than varieties having high stem proportion. leaf to stem ratio is an important trait in the selection of appropriate forage cultivar as it is strongly related to forage quality (julier et al., 2000; sheaffer et al., 2000). the proportion of leaves at the time of harvest is a major factor that determines the quality of the forage (jung, 2005; mihai et al., 2012). the relative feed value (rfv) of alfalfa varieties is presented in table 6. feeds with an rfv index higher than 100 are considered to be of higher quality compared to full bloom alfalfa hay and those with a value lower than 100 are of lower value (dunham, 1998). the rfv of the introduced supersonic alfalfa variety was slightly lower than the standard check variety. however, both the tested varieties had rfv index higher than 100 indicating the varieties had better nutritional quality. the rfv recorded in the present study was lower than the rfv reported by other researchers for different alfalfa varieties/genotypes (diriba et al., 2014; mekuanint et al., 2015; gezahagn et al., 2017). table 6: chemical compositions and in-vitro dry matter digestibility (g/kg dm) of alfalfa varieties parameters variety mean supersonic alfalfa-1086 (sc) ash 142.8 144.7 143.8 cp 198.7 209.0 203.9 ndf 488.4 484.9 486.7 adf 373.6 371.2 372.4 adl 70.8 68.0 69.4 ivdmd 606.1 612.5 609.3 rfv 115.9 116.1 116.0 cp = crude protein; ndf = neutral detergent fiber; adf = acid detergent fiber; adl = acid detergent lignin; ivdmd = in-vitro dry matter digestibility; rfv = relative feed value; sc = standard check. gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 62 table 7: response of alfalfa varieties for disease and pest incidence (%) during the study periods incidence (%) variety supersonic alfalfa-1086 (standard check) disease downy mildew 8.5 9.5 common leaf spot 10.5 12.0 aphanomyces root rot 7.5 11.5 bacterial wilt 11.5 12.5 pest aphids 11.5 13.5 3.5. reaction to diseases and pests the introduced supersonic alfalfa variety and the standard check variety were tested for their diseases and pests reaction starting from the initial stage of evaluation to verification stage and found to be resistant/moderately resistant to major diseases and pests which can affect the variety (table 7). the diseases and pest effects on the performance of alfalfa varieties were recorded as 0-10% resistant, 11-30% moderately resistant, 31-60% moderately susceptible, and 61-100% susceptible. accordingly, the registered supersonic alfalfa variety was found to be resistant to moderately resistant to the recorded major diseases (downy mildew, common leaf spot, aphanomyces root rot, and bacterial wilt) and pests (aphids) in the test locations during the experimental periods. the resistance reaction of the variety could be integrated with other diseases and pest management strategies for better results. generally, the registered supersonic alfalfa variety is superior in tolerance to major diseases and pests than the standard check variety. 3.6. adaptation the registered supersonic alfalfa variety is adapted to a wide range of environments in ethiopia. the variety performed very well in areas with an altitude of 750 to 2400 meters above sea level which has an annual rainfall of 800 to 1200 mm. it could also be possible to extend the production of the variety to other areas with similar agro-ecologies after conducting an adaptation trial. the registered supersonic alfalfa variety produces better dry matter yield, crude protein yield, and digestible yield when a recommended fertilizer rate and seeding rate are applied in nitosol and clay loam soils at sowing. for better performance, the variety should be planted in early june under rain-fed conditions and any time when irrigable water is available. in areas that receive high temperature and irrigable water, the variety can be harvested monthly and bimonthly for forage and seed yields, respectively. 4. conclusion after the national variety trial had been conducted over locations, the recently introduced supersonic alfalfa variety with the standard check (alfalfa-1086) was verified over locations and evaluated by the national variety releasing committee as per the guidelines of the variety releasing and registration of the country during the 2020 cropping season. based on their evaluation result, the supersonic alfalfa variety which had relatively better performance in terms of biomass production and diseases and pests reactions is registered in 2021 for production. the variety is well adapted in the low to high altitude areas and similar agro-ecologies of the country. the breeder and pre-basic seeds of the registered supersonic alfalfa variety are maintained by harvest general trading pvt. ltd. co. and the feeds and nutrition research program of holetta agricultural research center. acknowledgments the authors acknowledge the ethiopian institute of agricultural research for funding the research and harvest general trading pvt. ltd. co. for importing the variety and partially funding the research to register the variety. they also extend special thanks to the staff of the feeds and nutrition research program working in the respective research centers for their smooth implementation of the experiment. the animal nutrition research staff of holetta agricultural research center is duly acknowledged for their assistance in laboratory analysis. gezahagn kebede et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 63 references adugna t. 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(2009). análisis de crecimiento estacional de una pradera asociada alfalfa-pasto ovillo. téc. pecu. méx. 47: 173-188. 1 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper experimental investigation on the effect of teff straw fiber and lime on strength and compressibility of black cotton soil sifan teshome1, yadeta c. chemeda2, 1department of civil engineering, school of civil engineering and architecture, adama science and technology university, p.o. box: 1888, adama, ethiopia 2department of applied geology, school of applied natural sciences, adama science and technology university, p.o. box: 1888, adama, ethiopia article info abstract article history: received 02 may 2022 received in revised form 22 june 2022 accepted 26 june 2022 black cotton soils often do not meet the geotechnical requirement as they exhibit high swellingshrinkage behavior and compressibility. therefore, stabilization of such soils with different additives is a common practice in geotechnical engineering. on the other hand, replacing traditional stabilizers with industrial and agricultural by-products has both economic and environmental significance. in this work, the effect of teff straw fiber, which is one of the common agricultural by-products in ethiopia, on strength and compressibility characteristics of black cotton soil, was investigated. the combined effect of fiber reinforcement and lime treatment was also investigated. the black cotton soil sample was collected from sendafa town. samples of soil reinforced with various contents (0%, 0.5%, 0.75%, and 1% by weight) and lengths (20mm, 40mm, and 60mm) of teff straw fibers and mixed with various percentages of lime (2%, 4%, and 6%) were prepared to conduct compaction test, unconfined compressive strength (ucs) test, and consolidation test. the result showed that maximum dry density (mdd) decreased and optimum moisture content (omc) increased with increasing both fiber and lime percent, while usc increased until 0.75% for teff straw fiber with each length and 4% (optimum %) of lime. the strength increased by more than double when the soil is reinforced with optimum percentage (0.75%) of fiber content and treated with lime (4%) as compared to when the soil is stabilized by lime (4%) only. similarly, fiber reinforcement and lime stabilization significantly reduced the compressibility and swelling potential of soil. the finding of the work suggests that a combination of fiber reinforcement and lime stabilization is more effective for ground improvement than lime stabilization or fiber reinforcement alone. keywords: black cotton soil teff straw fiber strength compressibility 1. introduction all engineering structures are built on or in the ground. however, the undesirable behavior of black cotton soil such as high swelling-shrinkage, excessive and uneven settlement make constructions on expansive black cotton soils challenging (nelson and miller, 1992; prusinski and bhattacharja, 1999; atahu et al., 2019). avoiding construction on such soils is one alternative considered in engineering practice. however, currently corresponding author, e-mail: yadeta.chimdessa@astu.edu.et https://doi.org/10.20372/ejssdastu:v9.i2.2022.479 because of the limitation of land due to rapid population growth and increase in urban development, there is a tendency towards enhancing the properties of the soil and reuse it rather than avoiding the site. various soil improvement techniques such as mechanical method, soil reinforcement, or adding some admixtures within the soil are commonly employed to enhance the engineering properties of soil (diamond and kinter, http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.479 sifan teshome and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 2 1965; verhasselt, 1990; bell, 1996; maubec et al., 2017; guidobaldi et al., 2017; vitale et al., 2017). the suitability of particular methods depends upon the site condition and economy. chemical stabilization techniques involve the addition of chemical binders such as lime, cement, fly ash, etc., and a combination of them. in the presence of these additives, swelling potential and plasticity of clayey soil decrease in the short-term, and mechanical strength increases in the long-term (bell, 1996; almukhtar et al., 2010; pomakhina et al., 2012; eisazadeh et al., 2012; guidobaldi et al., 2017; vitale et al., 2017; das et al., 2021). the long-term stabilization is related to precipitation of cementitious hydrated gel, while the short term modification is related to exchange of surface cations by calcium. even though chemical stabilization improves mainly the soil property under compression, its effect on the tensile behavior of soil is minimal (wang et al., 2019). soil reinforcement is also an important practice in geotechnical engineering to enhance stability, increase bearing capacity and tensile strength, and reduces settlements and lateral deformation of soil (wang et al., 2019; murthi, 2020; taha et al., 2021). several researchers investigated the application of various inclusion of synthetic and natural fiber reinforcement in weak soils such as polypropylene, carbon, nylon, steel mesh, sisal, coir, bamboo, enset ventricosum, wheat straw, oil palm, palm kernel and coconut palm fiber (yusoff, 2010; hejazi, 2012; deb and narnaware, 2015; mehta, 2017; maja, 2018; salim et al., 2018; jeludin et al., 2019; wang et al., 2019; murthi, 2020; bao et al., 2021; taha et al., 2021; etc.). adding both synthetic and natural fiber in clay soil improves the tensile behavior and cohesion among the soil particles and reduces compression index and volume compressibility up to certain fiber content. moreover, combining fiber reinforcement with chemical treatment such as lime and cement has been reported to be more effective in altering undesirable soil behavior (khandaker, 2011; shen et al., 2021). however, the reported optimum fiber content in previous works was different for different fibers and soil type. therefore, it is important to know the optimum fiber content considering the fiber and soil type for use in the engineering practices. the use of locally available natural fibers as a reinforcement material can potentially be cost effective and environmentally friendly. hence, recently, there is a tendency to replace traditional chemical stabilizers and synthetic fibers with industrial and agricultural byproducts. teff straw fiber is agricultural by-products of teff which is the famous small-grained cereal in ethiopia. even though teff grain yield is low compared to other cereals, its processing generates significant amounts of agricultural by-product. the proper utilization of this material has both economic and environmental benefits. there are only a few studies that describe the beneficial use of teff straw fiber in soil improvement. it is found that random inclusion of teff straw in soil is effective in increasing compressive strength and unsoaked cbr values of expansive soil (tirfu maja, 2018; abebe arega, 2020). however, to date, there is no studies that focused specifically on the use of the teff straw fiber to improve compressibility performance of soil. the present work, therefore, aimed to investigate the influence of teff straw fiber on consolidation characteristics of black cotton soil. in addition, the combined effect of teff straw fiber reinforcement and lime treatment was also investigated. 2. materials and methods 2.1. expansive soil the black cotton soil sample used in this study was collected from sendafa town where the area is predominantly covered by expansive soil. in this town and surrounding areas, the high swelling and shrinkage potential of the soil and its effect is commonly manifested by cracks on floors, walls and pavement. the soil sample was collected from a depth of 1.5 m by excavating test pit. the basic properties of the soil are summarized in table 1. it is classified as ch and a-7-6 as per the unified soil classification and american association of state highway and transportation officials (aashto) classification system, respectively. 2.2. teff straw fiber and lime teff straw fibers were also collected around sendafa town from farming communities. it is the predominant cereal crop produced in the area and its processing produces large volume of straw fiber. a proper usage of this agricultural by-product material can obviously reduce storage areas and environmental concern arising sifan teshome and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 3 from the disposal. the physical characteristics of fiber were determined in the laboratory and the outcomes are tabulated in table 2. hydrated lime (ca(oh)2) with purity > 90% was used in this study. 2.3. experimental work four types of samples were prepared: pure soil, teff straw fiber reinforced soil, lime treated soil and lime treated-teff straw fiber reinforced sample (table 3). compaction, ucs on 7 days cured conditions, and consolidation test were conducted on the prepared samples. all tests were conducted as per astm standards. soil samples reinforced with different percentages (0.5, 0.75 and 1% by weight of dry soil) and lengths (20, 40 and 60mm) of teff straw fiber were prepared by mixing manually the fiber with soil. for each mix, the mdd and omc were determined from proctor compaction test. for ucs test, cylindrical soil sample were prepared by compacting the soil mixed with fiber at respective omc to attain the mdd. the test was conducted on samples at a deformation rate of 1%/min until shear failure. the correlations between compressive stress and strain were recorded to plot stress-strain curve and to identify the peak load. then, the optimum length and percentage of teff straw fiber were determined from the test result. for the preparation of lime treated-fiber reinforced soil, the soil sample were first thoroughly mixed with different percentages of lime (2%, 4%, and 6% by weight) and mixed with optimum length and percentage of teff straw. after that, the optimum lime content was added to soil and reinforced with optimum percentages of fiber for the consolidation test. the samples were subjected to compression and recompression. the loading and unloading were conducted by doubling and halving the load, respectively. the time duration for all load increments and decrements was 24 h. table 1: properties of soil properties results specific gravity 2.78 liquid limit (%) 81.8 plastic limit (%) 32.18 plasticity index (%) 49.62 free swell (%) 70 sand (%) 6.80 silt (%) 48.20 clay (%) 45.00 maximum dry density (mdd) (kg/m3) 1452 optimum moisture content (omc) (%) 24.06 natural moisture content (%) 40.31 table 2: physical characteristics of teff straw fiber properties result water absorption (%) 60.7 average length (cm) 5 average diameter (mm) 0.4 angle of bending before break 260o-280o color brown-reddish and white table 3: mix proportions of black cotton soil, lime, and teff straw fiber material used and mix proportion (%) test conducted standard compaction test ucs test one-dimensional consolidation test black cotton soil teff straw fiber lime percentage length 100    99.5 0.5 20 and 40mm   99.25 0.75   99 1   99.5 0.5 60mm   99.25 0.75    99 1   97.25 0.75 60mm 2   95.25 0.75 4    93.25 0.75 6   96 0 60mm 4   95.5 0.5 4   95 1 4  sifan teshome and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 4 20 30 40 50 60 70 80 90 100 0 0.5 1 u s c ( k p a ) fiber content (%) 20 mm 40 mm 60 mm 3. result and discussion 3.1. compaction characteristics figure 1 demonstrates the influence of teff straw fiber content and length on mdd and omc. it can be seen from the figure that mdd decreased and omc increased as the percentage of fiber increased. the effect is related to the lower density and high water absorption properties of fiber compared to the soil. on the other hand, as the length of fiber increased, both omc and mdd decreased. the decrease of omc with increasing fiber length in contrary to fiber content may be related to a strong reinforcement between soil particles by longer fibers that results lower porosity and water absorption. figure 1: variation of mdd (a)) and omc (b) of soil fiber percentages and lengths 3.2. strength of fiber reinforced soil figure 2 shows the influence of teff straw fiber content and length on strength of the soil. as the percentage and length of teff straw fiber increased, the ucs and cohesion of the soil tended to increase, but it decreased when the fiber content increased more than 0.75%. hence, 0.75% of fiber content is found to be the optimum percentage of fiber for different length. the strength of the soil increased due to a strong reinforcement between soil particles which restrict movement of soil particles during deformation by external load. this binding ability increased with increasing the length of the fiber (from 20 to 60 mm), however the effect is more pronounced when the fiber length increased from 40 to 60 compared to length change 20 to 40 mm. when the fiber content increased more than the optimum fiber content (0.75%), effect on soil particles reinforcement and strength is negative as the fibers occupies the space of the original soil particles and compactness of soil decreases (zhao et al., 2020). figure 2: variation of ucs with content of teff straw fiber 3.3. effect of lime on strength of fiber reinforced soil figure 3 shows the influence of lime treatment on strain-stress relationship of soil reinforced by optimum content of teff straw fiber (0.75%). the stiffness and strength of the fiber reinforced soil improved with increasing lime content up to 4% and decreased for a further increase to 6% (figure 4). therefore, lime content 1280 1320 1360 1400 1440 1480 0 0.2 0.4 0.6 0.8 1 1.2 m d d ( g /m 3 ) fiber content (%) 20 mm 40 mm 60 mm a) 10 15 20 25 30 35 40 0 0.2 0.4 0.6 0.8 1 1.2 o m c ( % ) fiber content (%) 20 mm 40 mm 60 mm b) sifan teshome and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 5 0.0 20.0 40.0 60.0 80.0 100.0 120.0 0 2 4 6 8 s tr e ss ( k n /m 2 ) strain pure soil soil + 0.75% fiber soil + 0.75% fiber + 2% lime soil + 0.75% fiber + 4% lime soil+0.75% fiber + 6% lime soil + 4% lime figure 3: stress-strain relationship of fiber reinforced soil for different lime content (7 days cured). of 4% is considered as the optimum lime percentage for further study. the improvement in strength of the soil with lime treatment can be attributed to the short-term cation exchange reaction and long-term pozzolanic reaction that leads to flocculation of soil particle and precipitation of cementitious material, respectively (diamond and kinter, 1965; verhasselt, 1990; bell, 1996; deneele et al., 2016; maubec et al., 2017; guidobaldi et al., 2017; vitale et al., 2017). it is also worth to notice that the increase in strength brought by combination of lime stabilization and fiber reinforcement is almost 8 times that derived from lime treatment alone (4% lime treated) for 7 days curing time. it indicates that a combination of teff straw fiber reinforcement and lime treatment is more effective for ground improvement than lime stabilization alone. in addition, the fiber reinforcement imparted strainhardening behavior to the mechanical behavior of the soil, while lime treated and raw soil exhibit strainsoftening behavior. 3.4. effect of lime on compressibility of fiber reinforced soil 3.4.1. compression and re-compression index the results of consolidation test are depicted in figure 4 as a relationship between the void ratio and the logarithm of effective stress curve for the untreated soil, fiber reinforced soil and fiber reinforced-lime treated soil. it can be seen that at a given pressure level, the void ratio of fiber reinforced soil and fiber reinforced-lime stabilized soil (figure 4) is lower than the natural soil. it can be attributed to the filling/closure of the void with teff straw fiber and cementitious hydrated gel. in addition, the compression index decreased when soil is reinforced with teff straw fiber, stabilized by lime and lime stabilization and fiber reinforcement coupled (figure 5). however, the combination of lime treatment and fiber reinforcement is more effective in decreasing the compressibility of the soil than lime treatment or fiber reinforcement alone. this is also noticed in the comparisons of the recompression index between the combined treatment and the individual treatments (figure 6). the effect is appeared to be coupling rather than a simple summation of their respective effects as the decrease in compression and recompression brought by 0.75% fiber reinforcement of 4% lime treated soil is higher than the sum of change brought by individual treatment. the reduction of recompression and compression index is probably due to the fiber reinforced soil mass and the soil particles cemented together by cementitious hydrated gel, which prevents soil particles movement during deformation and swelling during water absorption. sifan teshome and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 6 figure 4: void ratio-pressure curves (logarithm) for untreated and treated soils figure 5: void ratio-pressure curves (logarithm) for untreated and treated soils 3.4.2. consolidation characteristics the coefficient of consolidation, which is determined by using taylor’s square root of time fitting method for different loading pressure, increased both when the soil is reinforced with teff straw fiber and stabilized with lime. however, the change (increase) in coefficient of consolidation is more pronounced for a combination of fiber reinforcement and lime stabilization (figure 6). the increase in coefficient of consolidation implies that the duration of consolidation (i.e. the time for dissipation of excess pore water pressure) reduced after the soil treated with lime and reinforced by fiber. similar improvement of the coefficient of consolidation was observed for coir fiber (jeludin et al., 2019) and synthetic fiber (deb and narnawar, 2015) reinforced soil. this is probably related to increase in pore size or interconnected pore space due to flocculation of soil particles (by lime) and interlocking between the soil particles and fibers. this in turn increases the permeability of the soil. generally, the combination of lime treatment and fiber reinforcement in clay soil not only increases the stuffiness of the soil, but also increases the rate of consolidation 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 50 500 5000 v o id r a ti o pressure (kpa) soil + 0.75% fiber soil + 4% lime soil + 4% lime + 0.75 fiber pure soil 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 pure soil soil + 0.75% fiber soil + 4% lime soil + 0.75 fiber + 4% lime compression index recompression index sifan teshome and yadeta c. chemeda ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 7 figure 6: coefficient of consolidation versus pressure for different conditions. 4. conclusion in this study, the effect of teff straw fiber reinforcement, lime treatment and the combination of them on the strength and compressibility behavior of black cotton soil was investigated and the following conclusions were drawn: ‐ unconfined compressive strength of the soil increases when fiber content increases from 0% to 0.75% and decreases when fiber content increases > 0.75%. the specimens reinforced with 0.75% content of 60 mm length showed the highest strength. hence, the optimum teff straw fiber required for stabilizing the soil was found to be 0.75% by dry weight. ‐ the strength of soil also increased with increasing lime content from 0% to 4% and decreased for further increase to 6%. therefore, for the investigated soil, the optimum lime content was found to be 4%. ‐ the combination of fiber reinforcement and lime treatment produced high increase in strength of the soil as compared to lime treatment or fiber reinforcement alone. ‐ the combination of lime treatment and fiber reinforcement not only reduced the compressibility of the soil, but also increases the rate of consolidation which can reduce the duration of consolidation and leads to an improvement in the stability and bearing capacity of the soil. generally, a combination of teff straw fiber reinforcement and lime stabilization is more effective for ground improvement. in addition, the potential use of this fiber as a stabilization admixture has dual advantage in terms of cost and environmental concerns related to using chemical stabilizers. however, further research is recommended to explore and understand stabilization/or reinforcement mechanism. the durability of the stabilized soil shall also be checked as it is important requirement for use in engineering practice. acknowledgement the 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(2020). mechanical properties of fiber reinforced soil under triaxial compression and parameter determination based on the duncan-chang model. appl. sci., 2020(10): 1-16. 68 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper estimation of relativistic mass correction for electronic and muonic hydrogen atoms with potential from finite size source eshetu diriba kena, gashaw bekele adera haramaya university, department of physics, p.o.box 138, dire dawa, ethiopia article info abstract article history: received 25 april 2022 received in revised form 26 july 2022 accepted 28 july 2022 hydrogen is the simplest atom in nature which helps us to study fundamental properties and structure of atoms. in this work, the perturbed schrodinger equation is used to estimate relativistic mass correction with potentials from finite size sources. this study is done with the assumption that the changes in both energy eigenvalues and eigenfunctions are negligible when considering the finite size of the nuclei. the relativistic mass corrections to 1s 1/2 and 2s_1/2 states using potential from finite size source are obtained and compared with corrections using potential from point-like source. the results show that, for hydrogen-like atoms with light nuclei the relativistic mass corrections due to the finite size source roughly coincides with that of point-like source. however, for atoms with heavy nuclei the two corrections display strong disagreement in which the corrections with finite size nuclei are significantly smaller than that of point-like nuclei. thus, this study offers the first attempt at including relativistic mass correction to energy eigenvalues of electronic and muonic hydrogen-like atoms with finite-size nuclei. when experimental data become available, comparison of these theoretical predictions may give a better insight into how relativistic corrections are affected by finite-size nuclei. keywords: atomic structure charge distributions finite size source hydrogen-like atom muonic hydrogen point-like source relativistic mass correction 1. introduction the hydrogen atom is the simplest atom known to exist in nature, which makes it very suitable to study the fundamental properties and structure of atoms. the hydrogen atom consists of a single negatively charged electron that moves about a positively charged proton (hudson and nelson, 1990, adamu et al., 2018). in 1911, niels bohr introduced the first model of hydrogen atom based on planck’s hypothesis, which states that electromagnetic radiations can only be emitted or absorbed in quanta of energy. however, the complete understanding of the structure of atomic elements in the periodic table was made possible with the invention of new theory called quantum mechanics as of 1925 (beiser, 2003) e-mail: eshetudiriba444@gmail.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.474 in addition, recent studies show that it is possible to replace the electron in an atom by a muon to form muonic atom. in other words, muonic hydrogen is an atom consisting of the proton and the muon which is very similar to the well-known electronic hydrogen (pohl et al., 2013). as a result, theoretical descriptions of the two atomic types have many features in common. the main difference however, is the fact that the muon mass is about 207 times heavier than that of the electron. the massiveness of muon in turn results in a significant increase in the energy levels of the atoms (pohl, 2014 and patoary et al., 2018); and leads to the realization that muons tend to be close to the nucleus of an atom as http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022......... eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 69 compared to electrons in electronic hydrogen (eshetu diriba and gashaw bekele, 2021). in a simplest quantum description of hydrogen atom, its nucleus is assumed to be point-like in terms of its mass and charge distribution. nevertheless, the more realistic model treats the nucleus as having finite size distributions. the shift in energy eigenvalues and eigenfunctions due to the finite size nucleus of muonic hydrogen atom has been studied non-relativistically using perturbation theory (adamu and ngadda, 2017). but in relativistic framework, the dirac equation of bound muon can be solved exactly or using relativistic perturbation (niri and anjami, 2018, firew meka, 2020, adamu and ngadda, 2017, deck et al., 2005 and eshetu diriba and gashaw bekele, 2021). it is worth noting that the relativistic effects play key role in the studies of the molecular properties such as electron affinities, ionization potentials, reaction, dissociation energies, spectroscopic and other properties (iliaš et al., 2010 and pyper, 2020). the relativistic effects can also be used to investigate the rotation curve of disk galaxies which is significant at large radii (deur, 2021). in non-relativistic treatment of an atom, the standard schrodinger equation conveys only a limited amount of information about properties of the atom. for instance, consideration of relativistic effects such as relativistic mass correction, spin-orbit coupling and darwin terms, leads to a better description of atoms and their structure. traditionally, those corrections are taken into account for hydrogen-like atoms with coulomb potential from a point-like source (schwabl, 2008 and townsend, 2012). to the best of our knowledge, however, no work has been done that examines relativistic effects for those atoms with coulomb potential from a finite size source. according to ref. (niri and anjami, 2018 and deck et al., 2005), the corrections to energy eigenvalues due to finite size nucleus for muonic hydrogen in nonrelativistic treatment are negligibly small; and the same can be said for corrections to energy eigenfunctions. in this paper, the schrodinger equation has been revisited as an attempt to address the relativistic mass correction to electronic and muonic hydrogen-like atoms by replacing the point-like potential source with coulomb potential from finite size source. this is done so with the assumption that such replacement may not result in any significant shifts in both energy eigenvalues and eigenstates. finally, the results of this work are compared with those obtained for hydrogenlike atoms with point-like source charge for light and heavy atomic nuclei. 2. mathematical methodology in this chapter we are going to introduce the mathematical methodology and methods needed to achieve our research objectives 2.1. dirac equation: minimal coupling dirac equation for a particles in an electromagnetic field, 𝐴𝜇, is modified as [𝛾𝜇𝑖𝜕𝜇 − 𝑚𝐼]𝛹 = 0 ⟶ [𝛾 𝜇(𝑖𝜕𝜇 − 𝑒𝐴𝜇) − 𝑚𝐼]𝛹 = 0 (1) more explicitly eq. (1) can be written as [𝛾0𝑖𝜕0 − 𝑒𝐴0 + 𝛾 ⋅ (𝑖�⃗⃗� + 𝑒𝐴)− 𝑚𝐼]𝛹 = 0 (2) where, 𝛾0 = ( 𝐼 0 0 −𝐼 ), �⃗� = ( 𝑜 �⃗� −�⃗� 0 ), 𝐼 = ( 1 0 0 1 ) 2.2. algebra of gamma matrices 2.2.1. pauli matrices the pauli matrices are a set of 2 × 2 complex, hermitian, and unitary matrices 𝜎𝑥 = ( 0 1 1 0 ), 𝜎𝑦 = ( 0 −𝑖 𝑖 0 ), 𝜎𝑧 = ( 1 0 0 −1 ) (3) using the commutation and anti-commutation relation of pauli matrices we obtain 𝜎𝑖𝜎𝑗 = 𝛿𝑖𝑗 + 𝑖∑𝜖𝑖𝑗𝑘𝜎𝑘 (4) equation 4 helps us to prove the relation (�⃗� ⋅ a⃗⃗⃗)(�⃗� ⋅ �⃗⃗�) = 𝐴 ⋅ �⃗⃗� + 𝑖�⃗� ⋅ (𝐴 × �⃗⃗�) (5) 2.3. numerical calculation of calculation of relativistic mass correction we employ matlab 2013a software to numerically generate relativistic mass correction. finally, we plot the graph of electronic and muonic hydrogen atoms as a function of proton number. 3. formalism in this section, we cover the mathematical origin of relativistic effects and then derive relativistic mass corrections for hydrogen-like atoms with potential from point-like and finite size sources. in this work, we invoke the natural unit whereby we set ℏ = 𝑐 = 1. eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 70 3.1. reduction of dirac equation into non-relativistic equation in the presence of a spherically symmetric electromagnetic potential the dirac equation takes the form 𝐻𝜓 = (�⃗� ⋅ �⃗⃗� + 𝛽𝑚 + 𝑉(𝑟))𝜓, (6) where, the kinematic momentum operator is given in terms of vector potential 𝐴 as �⃗⃗� = 𝑝 − 𝑒𝐴 (7) the four parameters �⃗� and 𝛽 are written in block matrix format using pauli and identity matrices: �⃗� = ( 0 �⃗� �⃗� 0 ); 𝛽 = ( 1 0 0 −1 ) (8) let’s redefine the dirac spinor 𝜓, which is a four dimensional column vector as 𝜓 = ( 𝜙 𝜒 ) (9) substituting eqs. (6) (9) into eq. (6) gives (𝐸 − 𝑚 − 𝑉)𝜙 = �⃗� ⋅ �⃗⃗�𝜒 (10) (𝐸 + 𝑚 − 𝑉)𝜒 = �⃗� ⋅ �⃗⃗�𝜙 (11) in non-relativistic limit, we relate the relativistic and non-relativistic energies as (townsend, 2012 and maggiore, 2005) 𝐸𝑁𝑅𝑇 = 𝐸 − 𝑚 (12) plugging eq. (12) into eqs. (10) and (11) yields (𝐸𝑁𝑅𝑇 − 𝑉)𝜙 = 𝑖�⃗� ⋅ �⃗⃗�𝜒 (13) (𝐸𝑁𝑅𝑇 + 2𝑚 − 𝑉)𝜒 = �⃗� ⋅ �⃗⃗�𝜙 (14) the non-relativistic energy 𝐸𝑁𝑅𝑇 and the potential 𝑉 terms are very small in comparison with 2𝑚 and are therefore neglected (messiah, 1966). hence eq. (14) is approximated as 𝜒 = �⃗� ⋅ �⃗⃗� 2𝑚 𝜙 (15) inserting eq. (15) back into eq. (13) and we get 𝐸𝑁𝑅𝑇𝜙 = [ 1 2𝑚 (�⃗� ⋅ �⃗⃗�)(�⃗� ⋅ �⃗⃗�) + 𝑒𝐴0]𝜙, (16) where, the potential energy v has been expressed in terms of scalar potential𝐴0(𝑉 = 𝑒𝐴0). by using the property of pauli matrices, we may write (�⃗� ⋅ �⃗⃗�)(�⃗� ⋅ �⃗⃗�) = �⃗⃗�2 + 𝑖�⃗� ⋅ (�⃗⃗� × �⃗⃗�) = �⃗⃗�2 − 𝑒�⃗� ⋅ �⃗⃗�, which in turn allows us to re-express eq. (16) as 𝐸𝑁𝑅𝑇𝜙 = [ (�⃗� − 𝑒𝐴) 2 2𝑚 − 𝑒�⃗� ⋅ �⃗⃗� 2𝑚 + 𝑒𝐴0]𝜙. (17) the expression in eq. (17) is famously known as the pauli equation. this pauli equation can further be manipulated to become the non-relativistic schrodinger equation which naturally incorporate all relativistic corrections and appropriate for spin-half particles (maggiore, 2005): 𝐸𝑁𝑅𝑇𝜙 = [ 𝑝2 2𝑚 + 𝑉 − 𝑝4 8𝑚3 + 1 2𝑚2 1 𝑟 𝑑𝑉 𝑑𝑟 𝑆 ⋅ �⃗⃗� − 𝑒 8𝑚2 ∇⃗⃗⃗ ⋅ �⃗⃗� ]𝜙, (18) where, −𝑝4/8𝑚3 is the relativistic mass correction, the term 𝑆 ⋅ �⃗⃗� is spin-orbit coupling and ∇⃗⃗⃗ ⋅ �⃗⃗� is the darwin term. 3.2. relativistic mass correction for point-like source relativistic mass correction is often referred as kinetic energy correction, which can also be obtained from energy-momentum relation for relativistic particle in the limit |𝑝| ≪ 𝑚. as we can see from eq. (13) the perturbed hamiltonian due to relativistic mass correction is given by �̂�1 = − 𝑝4 8𝑚3 (19) the hamiltonian of unperturbed system is given by 𝐻0 = 𝑝2 2𝑚 + 𝑉 squaring both sides and rearranging give rise to 𝑝4 8𝑚3 = 1 2𝑚 (𝐻0 − 𝑉) 2 (20) by using eq. (20), we may rewrite eq. (19) as �̂�1 = − 1 2𝑚 (𝐻0 − 𝑉) 2 (21) the relativistic mass correction to energy levels of hydrogen atom can be written as (griffiths, 1995) ∆𝐸1 (𝑛) = ⟨𝜓𝑛𝑙𝑚|�̂�1|𝜓𝑛𝑙𝑚⟩ (22) putting eq. (21) into the above equation we obtain ∆𝐸1 (𝑛) = − 1 2𝑚 ⟨𝜓𝑛𝑙𝑚|(𝐻0 − 𝑉) 2|𝜓𝑛𝑙𝑚⟩ = − 1 2𝑚 [𝐸𝑛 2 − 2𝐸𝑛⟨𝜓𝑛𝑙𝑚|𝑉|𝜓𝑛𝑙𝑚⟩+ ⟨𝜓𝑛𝑙𝑚|𝑉 2|𝜓𝑛𝑙𝑚⟩] (23) eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 71 for a point-like nucleus the coulomb potential is given by 𝑉 = − 𝑍𝑒2 4𝜋 0 1 𝑟 = − 𝑍𝛼 𝑟 where, the fine structure constant is given by 𝛼 = 𝑒2 4𝜋 0 = 1 137 with such potential, eq. (23) becomes ∆𝐸1 (𝑛) = − 1 2𝑚 [𝐸𝑛 2 + 2𝐸𝑛 ⟨𝜓𝑛𝑙𝑚 | (𝑍𝛼) 𝑟 |𝜓𝑛𝑙𝑚⟩ + ⟨𝜓𝑛𝑙𝑚 | (𝑍𝛼)2 𝑟2 |𝜓𝑛𝑙𝑚⟩] (24) the expectation values of 1/𝑟 and 1/𝑟2 in the eq. (24) are given by (sakurai and napolitano, 2011) ⟨𝜓𝑛𝑙𝑚 | 𝑍𝛼 𝑟 |𝜓𝑛𝑙𝑚⟩ = 𝑚(𝑍𝛼) 2 1 𝑛2 = −2𝐸𝑛, (25) and ⟨𝜓𝑛𝑙𝑚 | (𝑍𝛼)2 𝑟2 |𝜓𝑛𝑙𝑚⟩ = 𝑍2𝛼2 𝑎0 2𝑛3 (𝑙 + 1 2 ) = 4𝐸𝑛 2 𝑛 (𝑙 + 1 2 ) , (26) where, 𝐸𝑛 = − 𝑚(𝑍𝛼)2 2 1 𝑛2 = − 𝑍2𝛼 2𝑎0 1 𝑛2 , (27) the bohr’s radius 𝑎0 for electronic hydrogen is given by 𝑎0 = 1 𝑚𝛼 by substituting the result in eqs. (25) (27) into eq. (24) produces ∆𝐸1 (𝑛) = − 𝑍2𝛼𝐸𝑛 𝑚𝑎0 1 𝑛2 [ 3 4 − 𝑛 (𝑙 + 1 2 ) ] (28) for 1𝑠1/2 state, eq. (28) reduces to ∆𝐸 1 (1𝑠1/2) = 5 4 𝑍2𝛼𝐸1 𝑚𝑎0 (29) similarly, for 2𝑠1/2 state eq. (28) becomes ∆𝐸 1 (2𝑠1/2) = 5 16 𝑍2𝛼𝐸2 𝑚𝑎0 , or ∆𝐸 1 (2𝑠1/2) = 5 64 𝐸1 (30) note that for muonic hydrogen, the relativistic mass corrections for 1𝑠1/2 and 2𝑠1/2 states are obtained from eqs. (29) and (30) by substituting the bohr radius 𝑎0 with 𝑎𝜇 ⋍ 1 207 𝑎0. 3.3. relativistic mass correction for finite size source evaluation of the first-order relativistic mass correction for hydrogen-like atoms with coulomb potential due to a finite size source also starts with eq. (23). so for the ground state one may write ∆𝐸 1 (1𝑠1/2) = − 1 2𝑚 [𝐸1 2 − 2𝐸1⟨𝜓100|𝑉|𝜓100⟩ + ⟨𝜓100|𝑉 2|𝜓100⟩] (31) where, 𝑉(𝑟) is the potential induced by a uniformly charged spherical nucleus and given by ( adamu and ngadda, 2017) 𝑉(𝑟) = { 𝑍𝛼(− 3 2𝑅 + 𝑟2 2𝑅3 ), for 𝑟 ≤ 𝑅 −𝑍𝛼 𝑟 , for 𝑟 > 𝑅 (32) by employing this potential, we can evaluate the expectation values of 𝑉(𝑟) and 𝑉(𝑟)2. let’s start with 〈𝑉(𝑟)〉 with respect to the 1𝑠1/2 state. that is ⟨𝜓100|𝑉|𝜓100⟩ = ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = ∫𝑅10 ∗ 𝑌00 ∗ 𝑉𝑅10𝑌00d𝜏 where, d𝜏 = 𝑟2d𝑟sin𝜃d𝜃d𝜙 = 𝑟2d𝑟dω let’s now rewrite the above integral as ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = ∫𝑅10 ∗ 𝑉𝑅10𝑟 2d𝑟∫𝑌00 ∗ 𝑌00dω (33) the spherical harmonics is normalized, so that the second integral becomes unity (krane, 988); and hence ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = ∫𝑅10 ∗ 𝑉𝑅10𝑟 2d𝑟. (34) in order to evaluate eq. (24), we partition the integration into two subintervals such that ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = ∫ 𝑅10 ∗ 𝑉𝑟≤𝑅𝑅10𝑟 2d𝑟 𝑅 0 + ∫ 𝑅10 ∗ 𝑉𝑟≥𝑅𝑅10𝑟 2d𝑟 ∞ 𝑅 (35) if we insert eq. (32) into eq. (35), then we may obtain eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 72 ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = 𝑍𝛼{∫ 𝑅10 ∗ (− 3 2𝑅 + 𝑟2 2𝑅3 )𝑅10𝑟 2d𝑟 𝑅 0 − ∫ 𝑅10 ∗ 1 𝑟 𝑅10𝑟 2d𝑟 ∞ 𝑅 } (37) the radial wave function of electronic hydrogen in 1𝑠1/2 state is given by (beiser, 2003) 𝑅10 = 2 𝑎0 3/2 𝑒 −𝑍𝑟 𝑎0 (38) where, 𝑎0 is the bohr radius of electronic hydrogen whose value is given by 𝑎0 = 5.29 × 10 −11m. substituting eq. (38) into eq. (37) we obtain ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = 4𝑍𝛼 𝑎0 3 {∫ ( −3 2𝑅 + 𝑟2 2𝑅3 )𝑟2𝑒 −2𝑍𝑟 𝑎0 d𝑟 𝑅 0 − ∫ 𝑟𝑒 −2𝑍𝑟 𝑎0 d𝑟 ∞ 𝑅 } (39) we now apply taylor expansion of the exponential factor in the first term on the right hand side of eq. (33). since 𝑟/𝑎0 ≪ 1, we can approximate as (arfken, and weber, 2005) 𝑒−2𝑍𝑟/𝑎0 ≅ 1 − 2𝑍𝑟 𝑎0 (40) so that ∫𝜓100 ∗ 𝑉𝜓100d𝜏 = 4𝑍𝛼 𝑎0 3 {∫ ( −3 2𝑅 + 𝑟2 2𝑅3 ) (1 − 2𝑍𝑟 𝑎0 )𝑟2d𝑟 𝑅 0 − ∫ 𝑟𝑒 −2𝑍𝑟 𝑎0 d𝑟 ∞ 𝑅 } = 4𝑍𝛼 𝑎0 3 {− 4𝑅2 10 − ∫ 𝑟𝑒 −2𝑍𝑟 𝑎0 d𝑟 ∞ 𝑅 } (41) by using product rule of differentiation we have d(𝑟𝑒 −2𝑍𝑟 𝑎0 ) = 𝑒 −2𝑍𝑟 𝑎0 d𝑟 − 2𝑍 𝑎0 𝑟𝑒 −2𝑍𝑟 𝑎0 d𝑟 rearranging, we get 𝑟𝑒 −2𝑍𝑟 𝑎0 d𝑟 = 𝑎0 2𝑍 𝑒 −2𝑍𝑟 𝑎0 d𝑟 − 𝑎0 2𝑍 d(𝑟𝑒 −2𝑍𝑟 𝑎0 ) (42) integrating the above equation, we obtain ∫ 𝑟𝑒 −2𝑍𝑟 𝑎0 d𝑟 ∞ 𝑅 = − 𝑎0 2 4𝑍2 𝑒 −2𝑍𝑟 𝑎0 | 𝑅 ∞ − 𝑎0 2𝑍 𝑟𝑒 −2𝑍𝑟 𝑎0 | 𝑅 ∞ = 𝑎0 2 4𝑍2 (1 + 2𝑍𝑅 𝑎0 )𝑒 −2𝑍𝑅 𝑎0 (43) substituting eq. (43) into eq. (41) we have ∫𝜓100 ∗ 𝑉𝜓100𝑑𝜏 = − 8𝑍𝛼𝑅2 5𝑎0 3 − 𝛼 𝑍𝑎0 (1 + 2𝑍𝑅 𝑎0 )𝑒 −2𝑍𝑅 𝑎0 (44) and also the expectation value of 𝑉2 can be given as ∫𝜓100 ∗ 𝑉2𝜓100d𝜏 = ∫ 𝑅10 ∗ 𝑉2𝑅10𝑟 2d𝑟 ∞ 0 = ∫ 𝑅10 ∗ [𝑉𝑟≤𝑅] 2 𝑅10𝑟 2d𝑟 𝑅 0 + ∫ 𝑅10 ∗ [𝑉𝑟≥𝑅] 2𝑅10𝑟 2d𝑟 ∞ 𝑅 = 4(𝑍𝛼)2 𝑎0 3 {∫ ( 9 4𝑅2 − 3𝑟2 2𝑅4 + 𝑟4 4𝑅6 )𝑟2𝑒 −2𝑍𝑟 𝑎0 d𝑟 𝑅 0 + ∫ 𝑒 −2𝑍𝑟 𝑎0 d𝑟 ∞ 𝑅 } (45) applying the taylor expansion on the exponential factor in the first integral term of eq. (45) and then carrying out the integration give rise to ∫𝜓100 ∗ 𝑉2𝜓100d𝜏 = 68(𝑍𝛼)2𝑅 35𝑎0 3 + 2𝑍𝛼2 𝑎0 2 𝑒 −2𝑍𝑅 𝑎0 (46) using eqs. (44) and (46), eq. (31) becomes ∆𝐸 1 (1𝑠1/2) = − 1 2𝑚 [𝐸1 2 + 16𝑍𝛼𝑅2𝐸1 5𝑎0 3 + 2𝐸1𝛼 𝑍𝑎0 (1 + 2𝑍𝑅 𝑎0 )𝑒 −2𝑍𝑅 𝑎0 + 68(𝑍𝛼)2𝑅 35𝑎0 3 + 2𝑍𝛼2 𝑎0 2 𝑒 −2𝑍𝑅 𝑎0 ] = − 1 2𝑚 {𝐸1 2 + 16𝑍𝛼𝑅2𝐸1 5𝑎0 3 + 68(𝑍𝛼)2𝑅 35𝑎0 3 + [ 2𝐸1𝛼 𝑍𝑎0 (1 + 2𝑍𝑅 𝑎0 ) + 2𝑍𝛼2 𝑎0 2 ]𝑒 −2𝑍𝑅 𝑎0 } (47) then for the 1𝑠1/2 state, the first-order relativistic mass correction for finite size nuclei becomes ∆𝐸 1 (1𝑠1/2) = − 1 2𝑚 {𝐸1 2 + 4𝑍𝛼𝑅(28𝑅𝐸1 + 17𝑍𝛼) 35𝑎0 3 + [ 2𝐸1𝛼 𝑍𝑎0 (1 + 2𝑍𝑅 𝑎0 ) + 2𝑍𝛼2 𝑎0 2 ]𝑒 −2𝑍𝑅 𝑎0 } (48) similarly, the first-order relativistic mass correction for the 2𝑠1/2 state is obtained by rewriting eq. (31) as ∆𝐸 1 (2𝑠1/2) = − 1 2𝑚 [𝐸2 2 − 2𝐸2⟨𝜓200|𝑉|𝜓200⟩ + ⟨𝜓200|𝑉 2|𝜓200⟩] (49) the expectation values of 𝑉 and 𝑉2 with respect to the 2𝑠1/2 state can now be evaluated in what follows. starting with that of 𝑉 we have ∫𝜓200 ∗ 𝑉𝜓200d𝜏 = ∫ 𝑅20 ∗ 𝑉𝑅20𝑟 2d𝑟 ∞ 0 eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 73 = ∫ 𝑅20 ∗ 𝑉𝑟≤𝑅𝑅20𝑟 2d𝑟 𝑅 0 + ∫ 𝑅20 ∗ 𝑉𝑟≥𝑅𝑅20𝑟 2d𝑟 ∞ 𝑅 (50) where, 𝑅20 = 1 2√2𝑎0 3 2 (2 − 𝑍𝑟 𝑎0 )𝑒 −𝑍𝑟 2𝑎0 (51) substituting eq. (51) into eq. (50) we obtain ∫𝜓200 ∗ 𝑉𝜓200d𝜏 = 𝑍𝛼 8𝑎0 3 {∫ 𝑉𝑟≤𝑅 (2 − 𝑍𝑟 𝑎0 ) 2 𝑒 −𝑍𝑟 𝑎0 𝑟2d𝑟 𝑅 0 + ∫ 𝑉𝑟≥𝑅 (2 − 𝑍𝑟 𝑎0 ) 2 𝑒 −𝑍𝑟 𝑎0 𝑟2d𝑟 ∞ 𝑅 } (52) in the limit 𝑟 ≪ 𝑎0, we can employ the binomial expansion for the one of the factors in the first integral becomes (2 − 𝑍𝑟 𝑎0 ) 2 = 4(1 − 𝑍𝑟 2𝑎0 ) 2 ≃ 4[1 − 𝑍𝑟 2𝑎0 ] (53) once again, we apply the taylor expansion to the exponential factor for the first integration and using eqs. (32) and (53), we have ∫𝜓200 ∗ 𝑉𝜓200d𝜏 = 𝑍𝛼 2𝑎0 3 ∫ (− 3𝑟2 2𝑅 + 𝑟4 2𝑅3 )d𝑟 𝑅 0 − 𝑍𝛼 8𝑎0 3 ∫ (4𝑟 − 4𝑍𝑟2 𝑎0 + 𝑍2𝑟3 𝑎0 2 )𝑒 −𝑍𝑟 𝑎0 𝑟d𝑟 ∞ 𝑅 by following similar steps as in eqs. (42) and (43) we have ∫𝜓200 ∗ 𝑉𝜓200d𝜏 = −𝑍𝛼𝑅2 5𝑎0 3 − 𝛼[ 1 4𝑍𝑎0 (1 + 𝑍𝑅 𝑎0 ) − 𝑍𝑅2 8𝑎0 3 + 𝑍2𝑅3 8𝑎0 4 ]𝑒 −𝑍𝑅 𝑎0 (54) and ∫𝜓200 ∗ 𝑉2𝜓200d𝜏 = ∫ 𝑅20 ∗ (𝑉𝑟≤𝑅) 2𝑅20𝑟 2d𝑟 𝑅 0 + ∫ 𝑅20 ∗ (𝑉𝑟≥𝑅) 2𝑅20𝑟 2d𝑟 ∞ 𝑅 = 17(𝑍𝛼)2𝑅 70𝑎0 3 + 𝛼2 [ 𝑍 2𝑎0 2 − 𝑍 4𝑎0 2 (1 + 𝑍𝑅 𝑎0 ) + 𝑍3𝑅2 8𝑎0 4 ]𝑒 −𝑍𝑅 𝑎0 (55) substituting eqs. (54) and (55) into eq. (49) we obtain ∆𝐸 1 (2𝑠1/2) = − 1 2𝑚 {𝐸2 2 + 2𝛼𝐸2𝑅 2 5𝑎0 3 + 17𝑍2𝛼2𝑅 70𝑎0 3 + [ 𝑍𝛼2 2𝑎0 2 + 𝛼𝐸2 2𝑍𝑎0 + ( 𝐸2 2𝑎0 − 𝑍2𝛼 4𝑎0 2 )𝛼𝑅 + ( 𝑍2𝛼 8𝑎0 4 − 𝐸2 4𝑎0 3 )𝑍𝛼𝑅2 + 𝑍2𝛼𝐸2 4𝑎0 4 𝑅3]𝑒 −𝑍𝑅 𝑎0 } (56) in case of muonic hydrogen-like atoms, we may use eqs. (48) and (56) to estimate the relativistic mass corrections to 1𝑠1/2 and 2𝑠1/2 states, respectively, by substituting 𝑎0 with 𝑎𝜇 whose value is given by 𝑎𝜇 = 2.56 × 10−13 m. 4. results and discussion the corrections in eqs. (28), (48) and (56) are converted into matlab source code to produce numerical results. we have used matlab software to generate the graph of relativistic mass correction versus proton number. the mass of muon and electron are obtained from codata and the nuclear radii for each nucleus is obtained from international atomic energy agency. table 1 contains the experimental values of important parameters such as rest masses of parti. by employing the experimental values of the parameters given in table 1, we can estimate the numerical values of first-order relativistic mass correction to 1𝑠1/2 and 2𝑠1/2 states for both types of hydrogen-like atoms in the unit of electronvolt (ev). table 2 displays those corrections using point-like and finite size charge distributions, separately, for atoms with light and heavy nuclei. it is evident that for electronic hydrogen-like atom, the first-order relativistic mass correction is more prominent in 1s_(1/2) state than 2s_(1/2) state for both types of charge distributions. it was indicated by the authors (xie et al., 2021) that the relativistic mass correction takes the negative values and decrease continuously. for point-like source, the relativistic mass correction of ground state has been calculated and the result have strong agreement with the present work (wikipedia, 2022). eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 74 table 1: experimental values of some parameters used in this numerical analysis. nucleus electron mass (𝐌𝐞𝐕) muon mass (𝐌𝐞𝐕) bohr radius of electronic atom (𝐌𝐞𝐕−𝟏) bohr radius muonic atom (𝐌𝐞𝐕−𝟏) nuclear charge radius (𝐌𝐞𝐕−𝟏) 0.5110 105.65836 268.21 1.2975 𝐻1 1 − − − − 0.00445 𝐻4 𝑒2 − − − − 0.00997 𝐿𝑖6 3 − − − − 0.01312 𝐵𝑒7 4 − − − − 0.01341 𝐶12 6 − − − − 0.01252 𝑍𝑛64 30 − − − − 0.01991 table 2: the first-order relativistic mass correction for electronic hydrogen-like atoms. nucleus ∆𝑬 𝟏 (𝟏𝒔𝟏/𝟐) with point-like source (ev) ∆𝑬 𝟏 (𝟏𝒔𝟏/𝟐) with finite size source (ev) ∆𝑬 𝟏 (𝟐𝒔𝟏/𝟐) with point-like source (ev) ∆𝑬 𝟏 (𝟐𝒔𝟏/𝟐) with finite size source (ev) 𝐻1 1 −9.0569 × 10 −4 −9.0655 × 10−4 −1.4717 × 10−4 −1.4772 × 10−4 𝐻3 𝑒2 −3.6227 × 10 −3 −2.7192 × 10−3 −5.8870 × 10−4 −3.5482 × 10−4 𝐿𝑖6 3 −8.1551 × 10 −3 −4.2899 × 10−3 −1.3246 × 10−3 −5.5065 × 10−4 𝐵𝑒7 4 −1.4500 × 10 −2 −5.8000 × 10−3 −2.3548 × 10−3 −7.4419 × 10−4 𝐶12 6 −3.2605 × 10 −2 −8.7599 × 10−3 −5.2983 × 10−3 −1.1314 × 10−3 𝑍𝑛64 30 −8.1511 × 10 −1 −4.3569 × 10−2 −1.3246 × 10−1 −7.0491 × 10−3 table 3 shows that the corrections due to point-like and finite size charge distributions, separately, for light and heavy nuclei muonic hydrogen. for muonic hydrogen-like atoms, the first-order relativistic mass correction, when considering point-like nuclei, has a better contribution in the 1𝑠1/2 state than the 2𝑠1/2 state over the whole range of 𝑍. however, the same cannot be said when taking into account finite size nuclei as the relativistic mass correction is more prominent in 1𝑠1/2 state than 2𝑠1/2 state for muonic hydrogen-like atoms with 𝑍 < 15. but for muonic atoms with heavier nuclei the situation changes in such away that the relativistic mass correction begins to exhibit strong influence over the 2𝑠1/2 state as compared to the 1𝑠1/2 state. table 3: the first-order relativistic mass correction for muonic hydrogen-like atoms. nucleus ∆𝑬 𝟏 (𝟏𝒔𝟏/𝟐) with pointlike source (ev) ∆𝑬 𝟏 (𝟏𝒔𝟏/𝟐) with finite size source (ev) ∆𝑬 𝟏 (𝟐𝒔𝟏/𝟐) with point-like source (ev) ∆𝑬 𝟏 (𝟐𝒔𝟏/𝟐) with finite size source (ev) 𝐻1 1 −1.8736 × 10 −1 −1.8609 × 10−1 −3.0447 × 10−2 −4.7251 × 10−2 𝐻3 𝑒2 −7.4946 × 10 −1 −5.5244 × 10−1 −1.2179 × 10−1 −2.2342 × 10−1 𝐿𝑖6 3 −1.68630 × 10 0 −8.5973 × 10−1 −1.9673 × 10−1 −5.5836 × 10−1 𝐵𝑒7 4 −2.99783 × 10 0 −1.15121 × 100 −4.8715 × 10−1 −9.6176 × 10−1 𝐶12 6 −6.74512 × 10 0 −1.71430 × 100 −1.09610 × 100 −1.93145 × 100 𝑍𝑛64 30 −1.68640 × 10 2 −7.62900 × 100 −2.74020 × 101 −6.92000 × 101 eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 75 figure 1: relativistic mass correction versus proton number for 1𝑠1/2 state electronic atom. figure 2: relativistic mass correction versus proton number for 2𝑠1/2 sate electronic atom. figures 1 and 2 depict that the results of both present work (finite size source) and point-like source for electronic hydrogen atom. the results show that as the atomic number (𝑍) increases, the relativistic mass corrections decrease for the two types of hydrogen-like atoms. the plots also clearly indicate that the correction with finite size charge distribution agrees with that of the point-like source in case of hydrogen-like atoms with light nuclei. nevertheless, as 𝑍 increases, there is strong deviation of the corrections with finite size distributions from the ones with point-like sources. eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 76 figure 3: relativistic mass correction versus proton number for 1𝑠1/2 state muonic atom. figure 4: relativistic mass correction versus proton number for 2𝑠1/2 state muonic atom. figures 3 and 4 illustrate the dependence of the relativistic mass correction on the proton number 𝑍 for 1𝑠1/2 and 2𝑠1/2 states of muonic hydrogen-like atoms. according to figure 3, as the atomic number increases so is the deviation of the relativistic mass correction to 1𝑠1/2 state with finite size nuclei from the one with point-like charge distribution. based on figure 4 the relativistic mass corrections to 2𝑠1/2 state of muonic hydrogen-like atoms with finite size and point-like nuclei show slightly better agreement as opposed to the case of the 1𝑠1/2 states of similar atoms. 5. conclusion in this paper, we have shown how, in non-relativistic limit, dirac equation can be reduced into schrodinger equation and we have presented the mathematical approach used to calculate the relativistic mass correction by using potentials from point-like and finite size source charge distributions. the results show that, for hydrogen-like atoms with light nuclei the relativistic mass corrections due to the finite size source roughly coincides with that of point-like source. however, for atoms with heavy nuclei the two corrections display eshetu diriba &gashaw bekele. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 77 strong disagreement in which the corrections with finite size nuclei are significantly smaller than that of pointlike nuclei. declarations competing interests: the authors declare that they have no competing interests. reference adamu, a., & ngadda, y. h. 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(2022). https://en.wikipedia.org/wiki/fine_structure xie, h. h., jiao, l. g., liu, a., & ho, y. k. (2021). high‐precision calculation of relativistic corrections for hydrogen‐like atoms with screened coulomb potentials. international journal of quantum chemistry, 121(13): e26653. 38 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper academic staffs’ motivation for leadership service in higher learning institutions: the case of four public universities in ethiopia alemu disassa mulleta*, alemu kebede, kumsa donis, daniel tessema adama science and technology university, school of humanities and social science, p. o. box 1888, adama, ethiopia * corresponding author, e-mail: alemuu.disasa@astu.edu.et abstract this study was aimed at assessing the readiness of academic staffs to serve in their university leadership. to this end, a descriptive survey research design has been employed. quantitative and qualitative data were collected from 386 academic staffs and top leaders of four public universities: adama science and technology university, addis ababa science and technology university, debre birehan university and arsi university using questionnaire, focus group discussions (fgd), and key informant interview (kii). the quantitative data were analyzed using descriptive and inferential statistics, whereas thematic analysis was employed for the qualitative data. the study reveals that, in spite of some irregularities, recruitment for middle and lower level leadership in public universities is carried out through open competition; however, academic staffs are less interested to serve in their university leadership mainly due to lack of willingness to sacrifice work-life balance, lack of transparency in the leadership selection process, and unnecessary government political interference. minimizing political interference, introducing attractive incentive packages, ensuring transparency and decentralization of power in universities have been recommended to curb the existing problems. keywords: university leadership, academic freedom, astu. 1. background and justification of the study higher learning institutions are responsible for creating educated work force that can advance the future of the nation and conducting researches which address the socio-economic challenges of a country. this necessitates higher learning institutions to have the prerogative to plan and act autonomously and achieve their missions in a flexible manner (mulatu dea and befikadu zeleke, 2017). however, factors related to their organizational features and their relative autonomy from government intervention often make the leadership in higher learning institutions difficult (clegg and walsh, 2004; kezar, 2001). hence, the success in the leadership of these institutions demands committed staffs with good motivation to take part in their university leadership. staff motivation to assume a leadership role is often determined by existing governance system, institutional factors and personal factors (njambi, 2014).according to a survey conducted by nicole torres (2014), asked about why they were not interested in managerial roles, more than half of the respondents (52 percent) reported they were satisfied in their current roles, a third (34 percent) responded they didn’t want to sacrifice worklife balance. in similar studies, employees reported that they refrain from assuming managerial roles because they did not feel their company would give them the opportunity due to institution related factors (kelli, 2010; gous, 2003). avolio and bass, (2004) believe that followers’ attitude and belief towards their leaders and the confidence they develop in their leadership largely determines their organizational commitment which includes http://www.ejssd.astu.edu/ mailto:alemuu.disasa@astu.edu.et alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 39 willingness to participate in the leadership their organization. in the context of academic institutions, factors such as transparency, academic freedom, superior–subordinate relationship, promotion opportunities, and the nature of job determine staff motivation for participation in leadership roles (njambi, 2014). local studies in the area revealed that the governance system that the federal ministry of education of ethiopia implements in higher learning institutions restricts the autonomy of universities (mulatu dea and befikadu zeleke, 2017; sisay tamirat, 2015). sisay tamira (2015:9) argues that “erroneous political interference by governments” has eroded the academic freedom in higher learning institutions in ethiopia. teshome (2003) also stressed that higher learning institutions in ethiopia are obliged to sacrifice their academic freedom owing to their financial dependence on the government. similarly, rigidity of hierarchical structure, outdated human resource policies, absence of incentives, lack of transparency, lack of confidence among the leaders in giving strategic direction, and centralized governance system were found to be characteristics of governance in public universities in ethiopia (mulatu dea and befikadu zeleke, 2017; lerra, 2014; behailu aschalew, 2011). these challenges, in turn, may hinder academic staffs’ motivation to take part in the leadership of their universities. in an institution where workers show reluctance to take leadership position, it is difficult to ensure effective leadership which can properly gear the institution towards its ultimate goal. hence, examining staff motivation for leadership helps to find out factors which hinder a given institution from achieving its mission. nevertheless, few studies have been conducted in the area so far at international and national levels to the best knowledge of the researchers of this study. the presence of such knowledge gap and our personal observation as lecturers, leaders, and researchers in public universities were what motivated us to carry out this scientific inquiry. in spite of the attempts made to make the leadership recruitment process open, the academic staffs seem to be reluctant to apply and compete for university leadership positions particularly the top and middle level management positions. although there could be institution specific factors, the researchers feel that there are problems which cut across similar higher learning institutions in the country. hence, the current study aimed at investigating the scenario in four public universities in ethiopia. to be more specific, the study attempted to examine the readiness of academic staffs of public universities to take part in their university leadership; identify the major factors that hinder academic staffs from participating in their university leadership and examine differences among the target universities on academic staffs’ readiness to participate in their university leadership. 2. materials and methods 2.1. participants in the current study, a cross-sectional descriptive survey research design with mixed approach to data collection and analysis has been employed to collect data from four public universities of ethiopia: adama science and technology university, addis ababa science and technology university, arsi university and debre birehan university. the universities were chosen mainly due to their geographical proximity. by the time the data for the current study were collected, september 2017, there were 2052 local academic staffs on duty in the target universities and of these staffs 428 were selected as data sources using simple random sampling, quota sampling and purposive sampling. 2.2. instruments a survey questionnaire with both closed-ended and open-ended items was used to examine the readiness of academic staff to take part in their university leadership and factors which hinder them from such participation. the questionnaire was developed by the research team and validated before it had been used for the main study. the content validity of the survey questionnaire was checked by using the research team as panel of experts. cronbach’s alpha value of the questionnaire, α= .80, was found to be in the acceptable range. out of 400 survey questionnaires distributed in the four universities, 358 (89.5percent response rate) were filled and returned for analysis. in addition to this, 7 kii and 4 fgds were conducted to obtain the qualitative data from higher level managers and selected academic staff, respectively. alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 40 11(7.53%) 26 (17.81%) 109 (74.66%) 0 20 40 60 80 100 120 i was elected by my staff i was assigned by higher officials through open competition 2.3 data analysis the quantitative data were entered into spss and analyzed by using both descriptive and inferential statistics. in the analysis of likert scale responses which range from 5= strongly agree to 1=strongly disagree were categorized into two as “agree’ and ‘disagree’ just to obtain big picture about participants agreement or disagreement. the quantitative data have been transformed to perform comparison of mean scores. the qualitative data was transcribed, translated into english language and analyzed thematically. 3. results and discussion 3.1. demographic information in the current study, 358 respondents (female11.3 percent and male 88.7percent) filled and returned the survey questionnaire. of these respondents, 115 (32.1 percent) were selected from adama science and technology university (astu), 100 (28 percent) from addis ababa science and technology university (aastu), 80 (22.4 percent) from debre birehan university (dbu), while the remaining 63 (17.6 percent) were selected from arsi university (au). the mean of the respondents’ service year is (m= 8.44, sd= 5.88). the majority of the respondents (77.1 percent) are lecturers, while 20.6 percent and 2.4 percent are assistant professors and associate professors, respectively. 3.2 respondents’ leadership experience more than half of the respondents, 201(56.9 percent), do not have leadership experience in their university; whereas 152 (43.1) percent reported that they have the experience. of those respondents who had served in leadership positions, 37 (43.0 percent) left their position after they completed their term, 27 (31.4 percent) resigned before completing their office term, 8 (9.3 percent) has been sacked from position, while the remaining 14 (16.3 percent) has left their position due to other reasons. a considerable percentage of respondents who resigned and sacked from position may indicate lack of interest among academic staffs to serve in the leadership position. as indicated in figure 1, of those respondents who have served in leadership positions, 109 (74.7 percent) has reported that they have come to position through open competition, while 26 (17.8 percent) reported being assigned by higher officials. the remaining 11 (7.5 percent) confirmed being elected by their colleagues. this may show that open competition has become common strategies used in the universities to bring staff to management position. the respondents reported that they have applied for lower management positions such as department head 40 (29.4percent), associate dean 29 (21.3 percent), and coordinator 27 (19.9 percent), middle level positions such as dean/director 31 (22.8 percent). only 2 respondents reported to have applied for higher management positions. one can reasonably deduce figure. 1: strategies respondents followed to come to position alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 41 from this data that open competition has become common strategies used in the universities to bring academic staffs to lower and middle level management positions. other participants of fgds and kiis also confirmed the presence of such practice though there are some irregularities. at the same time, respondents’ reluctance to apply for higher leadership position might indicate the absence of the chance due to procedure in the higher education proclamation no. 650/2009 which gives the mandate of appointing the president and vice presidents of universities for ministry or for the head of appropriate state organ and managing board of universities (federal negarit gazeta no. 64, 17th september 2009). in such procedures, it is more likely that government or party affiliated individuals are given priority to hold higher positions in universities. 3.3 academic staffs’ readiness to hold leadership position asked about their readiness to participate in their university leadership, 42 (13.5 percent) of the respondents reported that they are very much interested, 126 (40.5 percent) reported they are somehow interested, whereas 143 (46 percent) reported that they are not interested at all. fgd participants and key informants have also revealed that although their interest varies based on the type of positions they apply for, the academic staffs have generally less interest to hold leadership positions. according to these participants, it is quite common to see second round vacancies announced for the same positions due to lack of applicants. an fgd participant from aastu said, “mostly people from engineering are totally not interested to come to leadership position because they are paid per hour when they work outside...”a key informant from astu also added, “there is no interest to serve in management. i myself have been lobbied to come to position.... last time, we announced vacancy for director general position, but nobody applied” (kii, astu).the respondents mentioned various factors that hinder academic staffs from applying for leadership positions. 3.4 factors that hinder academic staffs’ participation in leadership participants were asked to rate 14 potential factors that are frequently mentioned in the literature as hindrances to employees’ participation in leadership positions. the factors are related to personal interest, institutional working system, and general government policy. 3.4.1 personal factors as can be seen in table 1, 54.2 percent of the respondents agree/strongly agree that holding leadership position consumes much of their time, while 47.5 percent reported that their desire to give priority for their personal duties as major personal factors that hinder their participation in their university leadership. on the other hand, 56.9 percent reported that the challenges of leadership position have little impact in hindering their interest to participate in their university leadership. similarly, 51.1 per cent of the respondents reported that fear of additional burden of leadership roles has little impact on their participation in their university leadership although this figure somehow contradict with the qualitative data. the data obtained from fgds, kiis and survey questions reveal that some academic staffs prefer to focus on their personal duties such as further study and researches. others consider leadership roles as additional burden which has little significance for their professional development and personal freedom. an fgd participant from au stated, “... i am engaged in routine activities although i am supposed to publish research articles....”a survey respondent from dbu added, “it [leadership service] seems good for nothing; it is routine work with no satisfactory output....” some participants of fgds also reported that academic staffs who provide leadership services often receive negative criticism at the end instead of rewards and appreciation which could enhance employees’ job satisfaction and their motivation for work according to kalimullah et al., (2010). alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 42 table 1: personal factors that hinder staff participation in leadership items response percent 5 4 3 2 1 i feel leadership positions are full of challenges i am not interested to face f 21 47 41 79 65 % 8.3 18.6 16.2 31.2 25.7 i need to give priority to my personal duties f 48 75 34 50 52 % 18.5 29.0 13.1 19.3 20.1 holding leadership position consumes much of my time f 53 88 47 37 35 % 20.4 33.8 18.1 14.2 13.5 i feel leadership job is simply additional burden to my life f 26 50 49 71 60 % 10.2 19.5 19.1 27.7 23.4 response 5= strongly agree, 4= agree, 3= undecided, 2= disagree, 1=strongly disagree fgd participants also reported that academic staffs who serve in their university leadership often face isolation being considered as government cadres. such feelings of the academic staffs may also reflect the magnitude of political interference in the management of higher learning institutions. concerning the impact of personal factors, a kruskal-wallis test shows no statistically significant difference h (3, n=247) = 1.94, p=0.585) among the four universities. in general, desires to give priority to personal duties, a tendency to consider leadership roles as additional burden which yield little benefit, and a tendency of considering leadership roles as the sole responsibility of cadres of the ruling party are found to be the major personal factors that hinder academic staffs’ participation in their university leadership. in relation to this, nicole torres (2014) revealed that 34 percent of the survey participants in his study declined from assuming leadership of their institution because they did not want to scarify their work-life balance. 3.4.2 institutional factors as shown in table 2, 69.6 percent of the respondents reported that lack of time to apply for leadership post does not hinder academic staffs’ participation in their university leadership. similarly, 62.8 percent and 50 percent of the respondents reported that discrimination based on ethnicity and discrimination based on regional background respectively has little impact on academic staffs’ motivation to serve in their university leadership. in contrast to this, 42 percent agree/strongly agree and 20 percent remain undecided that lack of transparency and fairness in the competition procedure is the major institutional challenge that hinders academic staffs’ participation in their university leadership. a considerable number of respondents, 34 per cent, also reported that they do not feel comfortable working with the existing management of their university. with regard to this, 20 percent of the respondents remain undecided. participants of fgds also reported that though there is open competition for leadership posts, sometimes individuals who have closer affiliation with the top management are selected for leadership posts disregarding the results of the competition. they also mentioned lack of transparency in disclosing results of contestants for the public, and lack of power decentralization as major institutional factors that discourage academic staffs from applying for leadership positions. most fgd participants have the feeling that middle and lower level managers have less power to exercise. for instance, an fgd participant from aastu said, “power with accountability should be given to deans. they should not be there to do only what they are told to do .....” as shown in table 3, a kruskal-wallis test result shows that there is no statistically significant difference h (3, n=241) = 1.79, p=0.616) among the four alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 43 universities on the impact of institutional factors on academic staffs’ motivation to serve in their university leadership. this indicates the prevalence of the problems across the target universities. however, visual observation of the mean rank shows that the impact of institutional factors is the highest in arsi university (mr=131.99), but the lowest in astu (mr= 114.06). table 2: institutional factors that hinder staff participation in leadership items response percent 5 4 3 2 1 1. no sufficient time was given to apply f 15 25 39 86 95 % 5.8 9.6 15.0 33.1 36.5 2. leadership position favors applicants who are typically from one region f 41 44 41 56 70 % 16.3 17.5 16.3 22.2 27.8 3. i do not feel the competition procedure in our university is transparent and fair f 55 54 52 48 51 % 21.2 20.8 20.0 18.5 19.6 4. i do not feel our university management would give me the opportunity because of my ethnic background f 23 27 44 64 95 % 9.1 10.7 17.4 25.3 37.5 5. i do not feel comfortable working with the existing management of my university f 46 89 50 60 55 % 18.4 15.6 20.0 24.0 22.0 responses= 5= strongly agree, 4= agree, 3= undecided, 2= disagree, 1=strongly disagree table 3: comparison of means on impact of institutional factors (m=12.97) universities n mr test statisticsa,b df h p astu 70 114.06 3 1.794 .616 aastu 73 121.05 dbu 54 120.97 au 44 131.99 in general, lack of transparency and fairness in the recruitment procedure, lack of proper power decentralization, and lack of interest to work with the existing management have been reported to have stronger negative impact on academic staffs’ motivation to serve in their university leadership. although lai (2011) asserts that power decentralization can boost workers motivation and satisfaction through nurturing sense of responsibility and trust in their organization, results of previous studies in ethiopia also revealed the absence of such practice in ethiopian higher learning institutions. behailu aschalew (2011) affirms that in ethiopian higher learning institutions “the overcentralization of authority in the hands of central executives heavily undermined the autonomy of academic units. ashebir bezabih (2016) and lerra (2014) also assert that higher learning institution in ethiopia is known for centralized decision-making structure. with regard to transparency, previous studies show that when employees feel that there is lack of fairness in the competition, they become reluctant to apply for managerial roles in their company (kelli, 2010; gous, 2003). mulatu dea and befikadu zeleke (2017:96) alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 44 describe the leaders of public universities in ethiopia as “neither accountable nor transparent.” behailu aschalew (2011) also claims that the current leadership appointment system by respective bureaucratic leaders in public universities in ethiopia is susceptible to bias and unfairness which in turn discourages academic staffs from participating in their university leadership. 3.4.3 government policy related factors as can be seen in table 4, 53.3 percent of the respondents agree/strongly agree that the political system is not inviting to apply for leadership position. similarly, 47.2 percent reported that lack of academic freedom hinder academic staffs’ participation in their university leadership. contrary to this, 64.4 percent of respondents disagree/strongly disagree that lack of additional benefit or incentive has impact on academic staff motivation for leadership position though this figure somehow contradicts with the qualitative data. similarly, 53.2 percent do not consider the competition criteria as a major hindrance to their participation in their university leadership. table 4: impact of government policy related factors on staff motivation for leadership factors responses percent 5 4 3 2 1 lack of academic freedom de-motivates me to apply for leadership positions f 67 52 50 51 44 % 26.6 20.6 19.8 20.2 13.0 the criteria do not go in consistence with my political belief/outlook f 45 34 42 48 90 % 17.4 13.1 16.2 18.5 34.7 holding leadership position does not offer me any additional benefit or incentives f 20 32 40 91 75 % 7.8 12.4 15.5 35.3 29.1 the political system is not inviting to apply for leadership position f 80 57 38 38 44 % 31.1 22.2 14.8 14.8 17.1 the incentive package for management positions is not attractive f 34 48 55 67 50 % 13.4 18.9 21.7 26.4 19.7 responses= 5= strongly agree, 4= agree, 3= undecided, 2= disagree, 1=strongly disagree fgd and key informant interview participants also mentioned lack of academic freedom or presence of political interference as major factor which discourages academic staffs from applying for leadership positions. the participants claim that excessive political interferences are observed especially in assigning university top management. in the procedure of appointing university president or vice presidents, the staff has almost no involvement as it has been clearly stipulated in the proclamation of higher education no. 650/2009. this may have its own negative impact on the leadership behavior and accountability of these top leaders in their interaction with their subordinates. the respondents also believe that due to lack of institutional autonomy, university managements often fail to execute as per their plan. for example, fgd participants from aastu reported that sometimes teachers are assigned to the university directly without asking the consent of the host departments. lack of proper incentive package was also widely raised by many fgd participants. an fgd participant from astu said, “the work load and the incentive allocated for service in leadership position are not compatible... people serving in the leadership suffer for nothing…” a key informant from the same university added, “what do you get from it [leadership position] unless you want to continue in the leadership profession and go up the ladder? ....you don’t’ benefit financially because you cannot initiate or lead a research project….” (kii, astu). in general, participants of the current study alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 45 0 2 4 6 8 10 12 14 16 18 astu aastu dbu au gov. pol.r factors institutional factors personal factors believe that serving in their university leadership has little financial and professional rewards compared the energy and time they exert. as a result, the staffs often prefer to engage in part-time jobs to supplement their salary. caparison of total mean of the four categories of hindering factors revealed that government policy related factors (m=14.22, sd=4.62) have the highest impact on academic staffs readiness to participate in their university leadership. however, no statistically significant differences have been observed among the four universities on the impact of the three categories of hindering factors as shown in table 5. this may indicate the prevalence of similar problems across public universities. however, the visual comparison of the means of the target universities on the three factors reveal slight difference among the universities as depicted in fig 2 below. table 5: overall impact of the three categories of hindering factors figure 2: comparison of mean on hindering factors as can be seen from figure 2, the impact of institutional factors and government policy related factors seem to be the highest in arsi university followed by debrebirehan university. similarly, the impact of personal factors is the highest in debrebirehan university, but the lowest in arsi university. in general, the results of the quantitative and the qualitative data reveal that government policy related factors such as lack of academic freedom, uninviting political environment, and lack of appropriate incentive package have significant impact on academic staffs’ readiness to serve in the leadership of their universities. the respondents are of the opinion that due to lack of institutional autonomy, one can hardly execute as per his plan. results of previous studies also strengthen the above findings. njambi (2014) argues that academic freedom and the existing opportunities for promotion determine staff motivation for assuming leadership roles. local studies also revealed that public universities in ethiopia hardly exercising their academic freedom due to excessive interference of the government, which is the sole source of their budget (mulatu dea and befikadu zeleke, 2017; sisay tamirat, 2015; behailu aschalew, 2011).these scholars describe mangers of public universities in ethiopia as mere implementers of government orders rather than strategic thinkers. the category of factors descriptive statistics anova n min max m sd df f sig. institutional factors 241 5.00 25.00 12.97 4.79 3 .446 .720 personal factors 247 4.00 20.00 11.54 3.88 .802 .494 gov policy factors 238 5.00 25.00 14.22 4.62 2.252 .083 alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 46 presence of such reality will, no doubt, discourage academic staffs’ motivation to serve in their university leadership. 4. conclusion and recommendations 4.1. conclusion based on the results of the qualitative and quantitative data presented and discussed in the preceding sections, the following conclusions have been drawn: although there are some irregularities, recruitment for middle and lower level leadership in public universities seem to be carried out through open competition. however, academic staffs in the target universities appear to have less interest to serve in the leadership positions especially in the top level leadership of their university due to various personal, institutional and government policy related factors. among the personal factors that hinder academic staffs’ participation in their university leadership are the need to give priority for personal duties, tendency to consider leadership roles as additional burden with little benefit for professional development, and considering university leadership as the sole responsibility of cadres of the ruling party. institutional factors such as lack of transparency and fairness in the leadership recruitment process, absence of power decentralization, and lack of interest to work with the existing management hinder academic staff participation in their university leadership. lack of academic freedom due to unnecessary political interference, and absence of attractive incentive package are among the major government policy related factors that seem to have discouraged academic staffs from serving in their university leadership. 4.2. recommendations based on the conclusions made in the preceding section, the following recommendations have been forwarded: 1. the government, specifically the federal ministry of education, need to take strategic actions to minimize unnecessary political interference and promote academic freedom and institutional autonomy of public universities in ethiopia. 2. the government also needs to introduce attractive incentive packages for the service in university leadership. this may help the academic staff to fully engage in university business rather than hunting for part-time jobs outside their university. 3. public universities in ethiopia should introduce better systems which can ensure fairness and transparency in recruiting academic staffs for university leadership. this may include establishing independent bodies which can play the role of check and balance. 4. universities also need to decentralize power to the middle and lower management structures to allow managers at these levels effectively implement their plans and encourage sense of ownership and responsibility. 5. owing to time and budget limitation, the current study was delimited to participants of four universities. hence, we feel that further studies with larger sample size and coverage could help in boosting the generalizability of the results of this study. acknowledgements the researchers would like to extend their heartfelt gratitude to adama science and technology university, office of research affairs, for covering the total cost of the study. all respondents involved in the current study also deserve our appreciation. we also thank data enumerators for patiently collecting the relevant data. alemu disassa et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 47 reference ashebir bezabih. (2016). power distance and its impact on academic staff performance in ethiopian higher education institutions. phd dissertation, addis ababa university. avolio, b.j. and bass, b.m. (2004) multifactor leadership questionnaire manual and sampler set. 3rd edition, mind garden, palo alto. behailu aschalew .(2011).the path of governance transformation in ethiopian higher education-institutional perspective, a tale of three universities experience with respect to business process reengineering (bpr) reform. european master in higher education (heem), university of oslo http://www.duo.uio.no/ clegg, c. and walsh, s. (2004). change management: time for a change! european journal of work and organizational psychology, 13, 217-239. gous, m. 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(2014). staff perception towards leadership in transforming wolaita sodo university: qualitative inquiry. open access library journal, 1http://dx.doi.org/10.4236/oalib.1100907. mulatu dea and befikadu zeleke (2017). governance of ethiopia public universities in southern region: professional & administrative accountability perspective. osr journal of humanities and social science (iosr-jhss), 22 (5), ver. 10 pp 86-98e-issn: 2279-0837, p-issn: 2279-0845.www.iosrjournals.org nicole t. (2014). most people don’t want to be manager: harvard business review. retrieved from https://hbr.org/2014/09/most-people-dont-want-to-be-managers. njambi c. (2014). factors influencing employee motivation and its impact on employee performance: a case of amref health africa in kenya. mba thesis, united states international university – africa. sisay tamirat (2015). academic freedom and the idea of university: a philosophical inquiry (with a reflection on addis ababa university). ma thesis, aau. teshome y. (2003). transformation is higher education: experiences with reform and expansion in ethiopian higher education system. moe, ethiopia. http://www.duo.uio.no/ http://surveys.canterbury.ac.nz/herdsa03/pdfsnon/n1071.pdf http://www.academicleadership.org/ http://dx.doi.org/10.4236/oalib.1100907 https://hbr.org/2014/09/most-people-dont-want-to-be-managers 37 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu research paper assessment of spare part sourcing and recycling activities impact on the availability of lead, cadmium and total petroleum hydrocarbon in evbareke spare parts market soil in benin city, nigeria moses o.1,, archibong u. d.2 1department of chemistry, faculty of physical sciences, university of benin, benin city, nigeria 2department of science laboratory technology, faculty of life sciences, university of benin, benin city, nigeria article info abstract article history: received 29 march 2022 received in revised form 14 june 2022 accepted 30 june 2022 recycling of spare parts obtained from dismantled unserviceable automobiles may be economical; however, it contributes to environmental degradation. the research was aimed at assessing the soil contamination intensity at evbareke spare parts market automobile disassembling site. soil sample collection was separately pull together from top soil (0-20 cm) at automobile disassembling location and evbareke senior secondary school serving as a reference/control site, using grid sampling method. the soil contamination level assessment index used include: relative pollution potential of the metals (rpp), single pollution index (spi), geo-accumulation index (igeo), average pollution index (api), total soil contamination index (tsci) and pollution load index (pli). the assessment was done with reference to data obtained from the control site soil as geochemical background value (cb). the contaminated soil particle size was categorized as loamy sand with coarse texture. the contaminated site soil had high total organic carbon content (toc) due to high value of the total petroleum hydrocarbon (tph) (107,304.59 mg/kg). lead and cadmium content in the geochemical fractionation of contaminated soil was more than that in reference site soil, due to human influenced contamination. rpp value revealed that the soil was contaminated at the impact point with lead and cadmium. the soil from the contaminated site soil was excessively contaminated with lead (37.11) and slightly contaminated with cadmium (1.57) based on spi assessment. igeo showed that the contaminated site soil was strongly contaminated with lead (3.21) and lightly contaminated with cadmium (0.05). the api assessment indicated that the soil was very highly contaminated by lead and cadmium (19.37). tsci and pli assessment showed that the contamination degree of the contaminated soil with lead and cadmium (38.68 and 13.98 respectively) was very high and the contaminant deteriorated the site. the impact of their activities has immensely contributed to lead, cadmium ions and petroleum hydrocarbon contamination in evbareke spare parts market vehicle dismantling site soil. keywords: contamination geochemical assessment ssourcing and dismantling automobile 1. introduction the activities of spare parts dealer to augment scarcity of spare parts of some vehicle has brought about sourcing for them by dismantling unserviceable vehicles and recycling the parts which has not worn out for reuse in repair of faulty vehicle. this activity may sound e-mail: okponmwense.moses@uniben.edu https://doi.org/10.20372/ejssdastu:v9.i2.2022.434 economical; however, it contributes to environmental degradation through spilling of unusable engine oil, fluids from condemned batteries and other electronic devices which find their ways into the soils through leaching (moses and obasigie, 2020). these wastes http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.434 moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 38 emanating from the activities of sourcing for spare parts can be very harmful to man on the long run due to the release of organic wastes and potentially toxic metal such as cadmium and lead into the soil environment (menkiti et al., 2017). soil contamination by means of heavy metals has severe health consequence with respect to humans, animals and plants. however, some heavy metals are essential for their growth and normal functions at trace quantity such as fe, zn, mn, cu, co and ni but large quantity; they may instigate acute or chronic toxicity. enduring consequence of lead (pb) vulnerability to man and higher animals may trigger plumbism, anemia, nephropathy, gastrointestinal colic and central nervous system symptoms, while prolonged exposure to cd can have detrimental consequences for instance lung cancer, bone fractures, kidney dysfunction and hypertension. (addis and abebaw, 2017; bakshi et al., 2018; proshad, et al., 2019). pb and cd have been discovered to hinder plant growth, intrude ion uptake and conveyance, including impeding enzyme activation and photosynthesis (afolayan, 2018). the subsequent release of heavy metals accumulated in soils or sediments to ground or surface water throw up an environmental hazard. heavy metals contamination degree in these media is reliant on their sources, redox conditions, microbial activities and physicochemical properties of solid and aqueous phases. heavy metals in soil generally refer to their bioavailability in the environment so that it can be absorbed or accumulated and have toxic effects on the biological traits of organisms (meng, 2017; bakshi et al., 2018). the heavy metals accumulated in soil possibly will be held, exchanged, precipitate or co-precipitate as sulphides, carbonate, oxide or hydroxide of iron (fe) or manganese (mn) by soil outside tolerable levels requests for worry because of damaging consequences of noxious metals on human, animals and plants. (sarkar et al., 2014; bakshi et al., 2018). owing to these activities of spare parts dealers, we found it necessary to carry out an evaluation of the effect of spare part sourcing bustles on availability of lead, cadmium and total petroleum hydrocarbon. in evbareke spare parts market soil to enables us decide how to manage the contaminated site in a cost-effective manner while preserving public and ecosystem health. 2. materials and methods 2.1 study area the research study area was the automobile disassembling site situated in evbareke spare parts market (latitude 6.36530 , longitude 5.60850) and evbareke senior secondary school (latitude 6.36510 , longitude 5.61130) was used as the control site, both in edo state, egor local government area nigeria (figure 1). the distance between the contaminated site and the control site is 708.58 meter (google, n.d) figure 1: map showing evbareke spare parts market and evbareke senior secondary school (google, n.d). 2.2 soil sample collection and processing the grid sampling method was employed for collecting soil sample. samples were taken at regularly spaced intervals. a set of sixty (60) samples out of a possible sixty-four (64) sampling points of contaminated soil samples were gathered at the deepness of 0-20 cm using soil auger, on a land area of about 450m2. the soil samples collected were combined together to form a compound sample. the debris in the composite sample was removed after which it was air-dried at environmental temperature, crushed and sieved to give ≤ 2 mm particle size. the left over moisture was got rid of by heat up at 105±5 0c for 6 hours in an oven. composite sample was kept in clean polyethylene bag, tied and stored prior to analysis. same procedure was followed for the control site soil collection. the soil composite sample from each site were individually physicochemically characterized for ph, particle size analysis – hydrometer method, electrical conductivity (ec), cation exchange capacity (cec), total phosphorus (tp), total petroleum hydrocarbon sampling (contaminat cont moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 39 (tph), total organic carbon (toc) and moisture content (mc) using standard method (north central region-13, 1998). heavy metals in soil was determined using sequential extraction procedures (fractionation), adopted from tessier et al., (1979). the heavy metal content in each fraction was analyzed using atomic absorption spectrophotometer (aas). 2.3 evaluation of heavy metal contamination degree in soil heavy metal contamination degree was evaluated by means of relative pollution potential of the metals (rpp), single pollution index (spi), geo-accumulation index (igeo), average pollution index (api), total soil contamination index (tsci), pollution load index (pli) for the soil from evbareke spare parts market as a result of automobile disassembling bustles (su et al., 2014; moses and obasigie et al., 2020). 2.3.1 relative pollution potential of the metals (rpp) relative pollution potential of a pollutant is a measure of the degree of chemical contact in the midst of the pollutant and the receiver. it is evaluated employing equation (1): rpp = cm−cb cm (1) where, cm is heavy metal concentration in contaminated soil site and cb is heavy metal concentration in untouched soil at the control site. if the results give positive values for the metals in question on the contaminated sites, it indicates that the soil was contaminated at the point of impact (anapuwa, 2014). 2.3.2 single pollution index (spi)/ contamination factor (cf) single pollution index/contamination factor of every single metal is a valuable way of measuring level of contamination comparative to either average earth crust constitution of particular metal or to the quantified background worth from geologically alike as well as unpolluted area. it is articulated as the relative amount of heavy metal concentration (cm) in soil to the acceptable degree of the country’s standards or reference point worth. heavy metal concentration in untouched soil at the control site was employed as background value (c¬¬b) (gushit et al., 2018; uzoije and nwigwe, 2018): the spi value is obtained using equation (2a) or (2b): spi =cm ∕cb (with reference to control site) (2a) or spi =cm∕tl (with reference to nesrea standard) (2b) where, tl is acceptable degree or highest acceptable concentration (hac) established on standards for soil quality as stated by the national environmental standard and regulations enforcement agency (nesrea, 2009) nigeria (rabe et al., 2018; uzoije and nwigwe, 2018; proshad et al., 2019). the degree of contamination was assessed employing spi predicting scale: <0.1 (very slight contamination), 0.1-0.25 (slight contamination), 0.26-0.50 (moderate contamination), 0.51-0.75 (severe contamination), 0.76-1.0 (very severe contamination), 1.1-2.0 (slight pollution), 2.14.0 (moderate pollution), 4.1-8.0 (severe pollution), 8.1-16.0 (very severe pollution), >16.0 (excessive pollution) (weissmannova and pavlovsky, 2017; gushit et al., 2018; chonokhuu et al., 2019). 2.3.3 average pollution index (api) average pollution index (api) evaluates degree of contamination by taking into consideration the link consequence of all metal contaminant in soil. api is gotten via computing the ratios of the average metal concentration with the worth obtained from control site as geochemical background value. it is gotten applying equation (3a), (3b) and (3c) (adedosu et al., 2013; uzoije and nwigwe, 2018): api = 1/n (spi1 + spi2 + spi3 +……+ spin) (3a) api = 1/n (cm1/cb1 + cm2/cb2 +cm3/cb3 + … + cmn/cbn) (with reference to control site) (3b) api =1/n (cm1/tl1 + cm1/tl2 + cm1/tl3 + …. +cmn/tln) (with reference to nesrea standard) (3c) where, cm1, cm2, cm3………., cmn are the average concentrations of the metal contaminants; tl1, tl2, tl3…….., tln are acceptable concentration for every single metal contaminants established on standards for soil quality as stipulated by nesrea, (2009); n is the total number of metals. degree of contamination was projected by means of the following scale: api ˂1= low level pollution, 1≤api ˂3 = moderate level pollution, 3≤api ˂6 = considerable level of pollution, api≥6 = very high pollution (cai et al., 2015; chonokhuu et al., 2019). 2.3.4 total soil contamination index (tsci) the total soil contamination index (tsci) most precisely describes the degree of contamination of soil by heavy metals or other microelements. the degree of moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 40 contamination (dc) of one decided space is the addition of entire contamination factors (cf)/single pollution index (spi) (bello et al., 2016) tsci is evaluated using equation (4). tsci = ∑ 𝑆𝑃𝐼𝑛𝑖=1 , where spi = cm/cb (4) the degree of contamination is predicted as follows dc<1 (low), 1≤dc<3 (moderate), 3≤dc<6 (considerable), dc≥6 (very high) (bello et al., 2016; kowalska et al., 2018). 2.3.5 geo-accumulation index (igeo) geo-accumulation index is a calculation of heavy metal contamination degree linked by means of the soil from automobile dissembling site. igeo value is achieved via equation (5) (weissmannova and pavlovsky, 2017; chonokhuu et al., 2019): igeo = log2 (cm/1.5cb) (5) where, cm is heavy metal concentration in contaminated soil and cb is geochemical background worth from control site. the degree of contamination was projected applying: igeo≤0 = uncontaminated, 0˂igeo≤1= light to moderately contaminated, 1˂igeo≤2 = moderately contaminated, 2˂igeo˂3 = moderately to strongly contaminated, 3˂igeo≤4 = strongly contaminated, 4˂igeo≤5= strongly to extremely serious contaminated, 5˂igeo ≤10= extremely seriously contaminated (bello et al., 2016; rabe et al., 2018; chonokhuu et al., 2019). 2.3.6 pollution load index (pli) pollution load index evaluates level of contamination. it signifies the number of times the amount of metal in soil goes above the average natural background concentration and provides a combined suggestion of total heavy metal toxicity degree in specific sample. control site soil sample was chosen to denote natural background. pli can give an assessment of metal contamination standing and needed proceedings to follow. pli is gotten from individual metal single pollution index with regard to natural background worth in soil using equation (6) (ololade, 2014; rabe et al., 2018): pli = (spi1 × spi2 × spi3 ×……., spin) 1/n (6) pli is categorized as pli ˂1 = soil perfection; pli=1= baseline level of pollutants (both class are unpolluted); moderately polluted (pli = 1–3), highly polluted (pli = 3–5) or very highly polluted (pli > 5) (darko et al., 2017; kowalska et al., 2018; uzoije and nwigwe, 2018). 2.4 mobility factor (mf) metals mobility in soil can be assessed based on total and comparative measure of fractions weakly combined to soil constituent. metal mobility relative index was evaluated as mobility factor (mf) based on equation 7: mf = 𝐹1+𝐹2+𝐹3 𝐹1+𝐹2+𝐹3+𝐹4+𝐹5+𝐹6 × 100 (7) where, f1 = exchangeable, f2 = carbonate, f3 = fe/mn oxide, f4 = organic and f5 = residual this equation is mainly the potential mobility of metals in soil (topcuoglu, 2016; topcuoglu, 2017). 3. results and discussion 3.1 results 3.1.1 physicochemical characterization of soil samples results of physicochemical and geochemical characterization of the soil samples are shown in table 1, depicting the quality of the contaminated soil as well as the control soil where automobile disassembly was not taking place. table 1: results of physicochemical characterization of the soil samples parameters units contaminated soil control soil ph 6.24 5.43 electrical conductivity ms/cm 1.04 0.235 total phosphorus mg/kg 372.58 202.20 total petroleum hydrocarbon mg/kg 107,304.59 4.04 cation exchange capacity cmol/kg 9.89 4.34 total organic carbon % 3.63 1.11 moisture content % 1.05 0.84 particle size analysis clay (%) 4.38 5.88 silt (%) 3.60 7.60 sand (%) 92.02 86.52 moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 41 3.1.2 geochemical characterization of soil samples for lead and cadmium geochemical characterization results for lead and cadmium in the contaminated soil as well as the control soil where automobile disassembly was not taking place is presented in table 2. 3.1.3 bioavailability and mobility factor of lead and cadmium in the soil samples vis-à-vis highest acceptable concentration (hac) by nesrea. the results of evaluation of the bioavailability and mobility factor of lead and cadmium ion in the contaminated soil as well as the control soil site where dismantling activities was not taking place is presented in table 3 and 4. 3.1.4 mobility factor determination mobility factor of lead and cadmium in soil samples is presented in table 4. 3.1.5 level of soil contamination assessment the results of the level of soil contamination assessment with respect to control site soil and nesrea tolerance limit as background values is presented in table 5. table 2: results of geochemical characterization of soil samples for lead and cadmium. fraction contaminated soil (mg/kg) control soil (mg/kg) lead cadmium lead cadmium soluble 0.21 0.03 bdl bdl exchangeable 1.07 0.20 bdl bdl carbonate-bound 7.50 0.20 0.71 bdl fe-mn oxide bound 21.07 0.47 0.71 bdl organically bound 3.21 0.20 bdl 0.07 residual 19.64 bdl bdl bdl total 52.70 1.10 1.42 0.70 bdl=below detectable level table 3: bioavailable lead and cadmium of the geochemical fraction in the soil samples vis-à-vis highest acceptable concentration (hac) by nesrea. fraction contaminated soil (mg/kg) control soil (mg/kg) lead cadmium lead cadmium soluble 0.21 0.03 bdl bdl exchangeable 1.07 0.20 bdl bdl carbonate-bound 7.50 0.20 0.71 bdl total 8.78 0.46 0.71 bdl hac (nesrea, 2009) 10 3.0 bdl=below detectable level table 4: mobility factor of lead and cadmium in soil samples. fraction contaminated soil (%) control soil (%) lead cadmium lead cadmium soluble 0.40 2.73 0.00 0.00 exchangeable 2.03 18.18 0.00 0.00 carbonate-bound 14.23 18.18 50.00 0.00 fe-mn oxide bound 39.98 42.73 50.00 0.00 organically bound 6.09 18.18 0.00 100.00 residual 37.27 0.00 0.00 0.00 mobility factor 16.66 39.09 50.00 0.00 moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 42 table 5: heavy metals assessment of contaminated soil with respect to control site soil and nesrea tolerance limit as background values 3.2 discussion 3.2.1 physicochemical characterization of soil samples the soil from the contaminated site had a higher total organic carbon content (toc) likened to control site, attributable to its high hydrocarbon material waste product from disassembled automobiles. the high content of the hydrocarbon material waste product can help to increase the soil adsorption strength hence contributing to decrease in metal mobility as well as bioavailability. the higher quantity of the toc was corroborated by the value of the total petroleum hydrocarbon (tph) value of 107,304.59 mg/kg from contaminated soil likened to 4.04 mg/kg from the control site soil (table 1). the contaminated site soil also had a higher cec value of 9.89 cmol/kg, however, because this value falls between 6 12 cmol/kg as opined by hazelton and murphy, (2007), the cation exchange rating was low, signifying that the capability of contaminated soil to hold and exchange cation was higher than that of control site soil which had a cec value lower than 6 cmol/kg (4.34 cmol/kg; table 1). the value of electrical conductivity obtained from the contaminated site and control site soil revealed that they both possess some level of salts (or salinity) and they both fell within a range safe for all crops. hanlon, 2012 stated that the values of 0-200ms/cm are safe for all crops (table 1). flynn (2015) classified a ph variety of 6.2 – 6.7 for soil as slightly acidic as well as a variety from 3.0 – 5.6 as strongly acidic. this denotes that contaminated site soil was slightly acidic whereas the control site soil was strongly acidic. metals have a tendency to be more accessible at lower ph as the ph increases toward 6.5 to 7 its availability reduces (li and thorton, 2001), this signified that metals availability in contaminated soil will be less owing to its higher ph worth of 6.24 compared to the control site with 5.43 ph value (table 1). particle size analysis showed that the contaminated soil fell into loamy sand class with coarse texture and control site soil fell into sandy loam class with moderately coarse general texture. in sandy loam soils, organic matter breakdown quicker than in fine-texture soils as a result of greater amount of oxygen on hand for their decomposition, while the breakdown of organic matters is slower in loamy sand. the content of total phosphorus in the forest soil characterized by lemanowicz (2018), ranged from 157mg/kg to 376 mg/kg. the total phosphorus obtained from the contaminated site and the control site soil studied fell within this range an indication that the value of the total phosphorous obtained – 372.58 mg/kg and 202.20 mg/kg in that order (table 1), were within safe zone for plants. 3.2.2 geochemical characterization of soil samples for lead and cadmium. in the contaminated soil, the lead and cadmium quantity in the mobile phase fraction, that is, the sum of soluble, exchangeable and carbonate bound (8.78mg/kg and 0.43 mg/kg respectively, table 2) are less than the lead and cadmium amount in the immobile phase of the fractionation, that is, the sum of fe-mn oxide bound, organic bound and residual (43.92mg/kg and 0.67mg/kg respectively, table 2). in both the mobile phase and the immobile phase of the fractionation, the quantity of lead was very high compared to the quantity of cadmium. in the soil obtained from the control site, the lead in the mobile amounted to 0.71mg/kg while the cadmium was below detectable level. the quantity of the lead and parameters contaminated soil assessment pb2+ cd2+ pb2+ cd2+ control site (as geochemical background value-cb) nesrea tolerance level (tl) (as geochemical background value-cb) rpp 0.97 0.36 0.80 -8.09 spi 37.11 1.57 5.27 0.37 igeo 3.21 0.05 1.26 -1.41 api 19.37 2.82 tsci 38.68 5.64 pli 13.98 0.76 moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 43 cadmium in the immobile phase were 0.71mg/kg and 0.07mg/kg respectively. on the overall, the content of lead and cadmium in the geochemical fractionation of contaminated soil is greater than that of control site soil, this was an indication of anthropogenic contamination of the contaminated soil as a result of automobile disassembling activities. 3.2.3 bioavailability and mobility factor of lead and cadmium in the soil samples vis-à-vis highest acceptable concentration (hac) by nesrea an assessment of the sum of the lead and cadmium concentration in their soluble, exchangeable and carbonate fraction with highest acceptable concentration (h.a.c) from nesrea, (2009), revealed that lead and cadmium content in its mobile or bioavailable form in contaminated soil were below that of nesrea, likewise in control site soil the lead and cadmium were below the nesrea, (2009) tolerant level (table 3). the mobility factors of lead and cadmium in contaminated soil 16.6% and 39.09% respectively (table 4), revealed that the cadmium had a higher mobility factor compared to lead. the mobility as well as bioavailability of lead and cadmium in the contaminated site soil are low. the low lability was due to the high amount of the organic waste from the automobile disassembling pursuits at the spare parts market, the low lability revealed that the organic waste had formed complexes with the heavy metals which are insoluble, resulting in reduced mobility and bioavailability. nevertheless, the mobility factor of lead as well as cadmium in control site soil was 50% and 00% respectively (table 4). 3.3 level of soil contamination assessment the level of lead and cadmium contamination of the soil owing to automobile spare parts disassembling bustles was assessed using rpp, spi, igeo, api, tsci and pli. the values obtained for rpp revealed that the soil was contaminated at impact point with lead and cadmium as a result of the motor vehicle spare parts dismantling activities at the site with respect to control site values as the geochemical background value (cb). however with nesrea tolerance limit as the geochemical background value (cb), it was observed that the cadmium contaminant in the contaminated soil was not as a result of the bustles of motor vehicle spare parts dismantling because of the negative value obtained from its evaluation (-8.09; table 5), the rpp value of the lead contaminant in the contaminated site using nesrea tolerance limit as the geochemical background value (cb) confirmed that lead contaminant in the contaminated site soil was as a result of the motor vehicle spare parts dismantling activities at the site (0.80; table 5). judging from the predicting scale of spi, it was observed that soil from contaminated site where the automobile disassembling bustle occurred was excessively contaminated with pb2+ (37.11) and slightly contaminated with cadmium (1.57) using control site values as the geochemical background value (cb). however, when nesrea tolerance level (tl) was used as the geochemical background value-cb), it revealed that the lead contaminant (5.27) severely contaminated the soil and the cadmium contaminant (0.37) moderately contaminated the soil (table 5). the predicting scale of geo-accumulation index revealed that the contaminated site soil was strongly contaminated with lead (3.21) and lightly contaminated with cadmium (0.05) using control site values as the geochemical background value (cb). however, using nesrea tolerance limit values as the geochemical background value (cb), revealed that the lead contaminant (1.26) moderately contaminated the soil while there was no cadmium contaminant (-1.41) in the soil (table 5). the api assessment revealed that both lead and cadmium (19.37) very highly contaminated the soil with respect to control site as geochemical background valuecb, while both contaminants (2.82) moderately contaminated the soil when nesrea tolerance level (tl) was used as geochemical background value-cb (table 5). tsci assessment revealed that the degree of contamination of the contaminated soil with lead and cadmium (38.68) was very high with respect to control site as geochemical background value-cb and their degree of contamination with respect to nesrea tolerance level values as geochemical background value-cb was considerable (5.64) (table 5). the pli employed to judge the contamination degree, revealed that amount of lead and cadmium in the contaminated site soil deteriorated the site in relation to control site as geochemical background value-cb, while the use of nesrea tolerance level values as moses o. and archibong u. d. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 44 geochemical background value-cb revealed that the lead and cadmium contamination did not in any way deteriorate the soil, in other words, the soil is in a perfect state. 4. conclusion the activities of sourcing for spare parts through dismantling of unserviceable vehicle for reusable parts has contributed immensely to cd2+, pb2+ ions and petroleum hydrocarbon contamination of evbareke spare parts market vehicle dismantling site soil. the contaminated site’s soil had high total organic carbon content (toc) due to high value of the total petroleum hydrocarbon (tph) value. the mobility as well as bioavailability of lead and cadmium in the contaminated soil, with a mobility factor of 16.6% and 39.09% respectively, is low, due to high amount of organic waste from the automobile disassembling bustles at the spare parts market. the assessment parameters revealed that the soil was contaminated at the point of impact with lead and cadmium. the contaminated soil was excessively or strongly contaminated with pb2+ and slightly or lightly contaminated with cadmium. the lead and cadmium very highly contaminated the soil and their degree of contamination of the contaminated site soil was very high and the contaminant deteriorated the contaminated site soil with reference to control site soil. implication national environmental standards and regulations enforcement agency of nigeria (nesrea) should as a matter of urgency promulgate laws which carries heavy fines or jail term attached as well as come up with ideal methods of disposing wastes arising from this spare parts sourcing process so as to reduce or eliminate incessant environmental contamination occasioned by this process through dismantling of unserviceable automobiles. also, materials which can help to immobilize the heavy metals as well as adsorb the hydrocarbon waste should be developed to help fight the already contaminated environment. acknowledgment we acknowledge the 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(2017) ‘indices of soil contamination by heavy metals – methodology of calculation for pollution assessment (minireview)’. environ monit assess, 89:616. 28 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper soil phosphorus adsorption characteristics and kinetics under different types of land use in dire inchine district, west showa zone, oromia, ethiopia achalu chimdi ambo university, department of natural resource management, p.o box 19, ambo, ethiopia article info abstract article history: received 22 july 2022 received in revised form 08 november 2022 accepted 14 november 2022 soil phosphorus is an essential plant nutrient, and its insufficiency severely limits crop yields. however, its adsorption study plays a vital role in devising appropriate soil phosphorus, “p”, management practices for its use proficiency. this study was initiated to evaluate phosphorous adsorption characteristics and kinetics of soil of three different land uses. a representative topsoil samples (0-20 cm) depth from the forest, grazing, and cultivated lands were collected and weighed 1g of composited soil samples were equilibrated in 20 ml of 0.01 m cacl2 solution containing kh2po4 at rates of( 0, 5, 25, 100, 150 and 250) mg p l -1 for assessment of langmuir adsorption isotherm using batch type experiment. then, the equilibration time was deduced from the kinetic experiment and fixed at 5 hours. the textural class of soils of forest land was clayey loam, whereas that of grazing and cultivated lands was clayey. soil ph values under the three land uses were found to be strongly acidic. the experimental soils differed considerably in sorption characteristics under the three land uses. the highest mean value of the product of biding energy and sorption maximum (kqmax) was recorded in the soil of cultivated land (1.08 lmg-1) followed by forest land soil (0.7313 lmg-1), while the lowest was recorded for the soil of grazing land (0.672 lmg-1), indicating considerable variation soil phosphorus adsorption characteristics under three land-uses. the value of the regression equation (r2) indicated that higher values (r2 > 0.9864) have better soil binding strength than the others. thus, the good fitness of the model was ascertained by witnessing the r2 values. the kinetic data showed that the values of concentration of soil “p” adsorbed (qe) under the three land uses were closer and the r2 values were comparably lower and almost analogous for the pseudo 1st order kinetic model than the pseudo 2nd order model. soil “p” sorption kinetics was fast in the first 120 minutes and then showed no change with the increase of the contact time. keywords: kinetics, land uses, langmuir models, “p”adsorption, pseudo 1st and 2nd order model 1. introduction soil deprivation and acidification are mainly caused by unsustainable land use management practices. appropriate land use management practices have significant influences on soil quality indicators, particularly at the surface horizon (wakene and heluf, 2003). a study by achalu et al., (2012) observed that changes in land use, particularly the conversion of forest land to continuous cultivation land with low inputs and overall poor management corresponding author, e-mail: achaluchimdi@yahoo.com https://doi.org/10.20372/ejssdastu:v10.i1.2023.526 practices, are the causes of the decline of soil nutrients and creation of the depletion of organic matter stock and intensification of soil acidity. phosphorus, “p”, is one of the essential macronutrients that determine crop growth and productivity. however, its deficiency limits crop production in most agricultural areas of ethiopian highlands (bereket et al., 2018). its deficiency is mainly due to the tight adsorption of “p” by fe-, alhttp://www.ejssd.astu.edu/ achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 29 oxides/hydroxides compounds in soil (xavier et al., 2009; jalali and tabar, 2011; asmare et al., 2015). as a result, soil “p” concentration and amount of plant available form of “p” in the soil are usually often inadequate to meet plant requirements (bereket et al., 2018; bati and achalu, 2021). moreover, soil solution “p” is usually quite low due to the complex interactions of phosphate with various soil components (shen et al., 2011). this low “p” in soil solution becomes the major limitation on agricultural crop production and productivity (achalu et al., 2013). it can also be attributed to its sorption with cations such as aluminum (al) and iron (fe) oxides in acid soils and precipitation reaction of “p” with calcium (ca) in calcareous soils of arid and semi-arid regions (zhang et al., 2005; palomo et al., 2006; kisinyo et al., 2014; bati and achalu, 2021). soil “p” sorption is considered to be the most important process controlling “p” availability in soils. phosphorus sorption is mainly studied by sorption isotherms which were historically initiated for evaluating its availability for crop uptake but have become popular for assessing the soil “p” mobility in the soil environmental system(achalu et al., 2013). sorption isotherm is a key in differentiating soils into their sorbing characteristics & practicing appropriate remedies based on the intensity of “p” sorption of a particular soil (hargopal & pritpal, 2011). the intrinsic low soil “p” and its robust sorption properties turn large proportions of its concentration into unavailable forms aggravating the problem, and this becomes a severe challenge for consequential “p” uptake in acidic soil areas (achalu et al., 2013; achalu, 2014; bereket et al., 2018). many soil chemical processes are always in dynamics and their kinetic chemical reactions are used to fully understand the vigorous interactions of plant nutrients with soils in a certain time scale (scheidegger and sparks, 1996; pal, 2011; mekdes et al., 2022). knowledge of the kinetics of dynamic interactions of plant nutrients is important to determine how rapidly reactions reach equilibrium ((liang et al., 2015). even though soil “p” sorption capacity has been studied in some of the acidic soil areas, little attention has been given to studying soil p adsorption and the kinetics process. therefore, to fill the gap, the present study was initiated to characterize “p” sorption characteristics and its kinetics as affected by land use types and to provide an indication for effective management of soil “p” and valuable information regarding how “p” performs in soils and the forecasting of soil phosphate fertilization. 2. materials and methods 2.1. site selection, soil sampling and preparation: the potentiality of representativeness of land uses has been confirmed through reconnaissance surveys and before collecting targeted soil samples. accordingly, three major representative land uses (forest, grazing and cultivated lands of upper, middle and lower slope positions of the study area) were identified (figure 1). replications of composited soil samples from 0-20 cm depth of each land use was collected, dried, sieved, prepared, labeled, and transported for laboratory analysis. 2.2. soil laboratory analysis and determination: composited soil sample of 0-20 cm depth from each land use was collected for the determination of targeted parameters of soil properties. soil texture was measured by the bouyoucos hydrometer method as described by day (1965). soil bulk density was determined from undisturbed soil samples collected using a core sampler. an average value of soil particle density of 2.65g cm-3 was considered for the calculation of total soil porosity. the total porosity was estimated from bulk and particle densities as described by brady and weil (2016) (equation 1). total porosity (%) = (1db/pd) x 100 (1) where: db = bulk density in (g.cm-3) and pd = particle density (g.cm-3) soil ph was measured using a digital ph meter as a suspension of a 1:2.5 soil-water ratio (baruah and barthakur, 1997). soil organic carbon (oc) was determined by the oxidation method (baruah and barthakur, 1997). soil total n was determined using the micro-kjeldahl digestion procedure as designated by (bremner and mulvaney, 1982). soil available “p” was analyzed using the bray ii method (bray and kurtz, 1945) and the interpretation was computed by using a spectrophotometer at a wavelength of 880 nm. achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 30 figure 1: location map of the study area 2.3. langmuir phosphorus adsorption study of experimental soils soil “p” sorption study was determined by batch type experiment in which soil samples were agitated with “p” solutions of known concentrations (graetz and nair, 2008; achalu, 2022). to measure the soil “p” sorption features, replicas of one gram of air dried soil samples of the three land uses were equilibrated in 20 ml of 0.01 m cacl2 solution containing kh2po4 at rates 0, 5, 25, 100, 150, and 250 mg p l-1 for 24 hours using mechanical shaker and batch type technique. from 2-3 drops of chcl3 were supplemented to abolish microbial growth (selfdavis et al., 2000). at end of the equilibration period, soil suspensions were centrifuged at 5000 rpm for 20 minutes, and then the adsorptive soil solution was separated from the adsorbent by centrifugation followed by filtration using a 0.45 µm membrane filter (achalu, 2022). the filtered solution was then taken for measurement of the concentration of the initial available “p” sorbed using a spectrophotometer at a wavelength of 880 nm (john, 2009). numerous models have been used to describe investigational data for sorption isotherms. amongst these, the langmuir isotherm model was used for this particular study. attained sorption data were fitted to the langmuir equation isotherm (equation 2). the achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 31 quantity of added “p” sorbed by the soil (s`) was calculated from the difference between “concentration in the equilibrium solution and the initial “p” added to the soil. to stabilize “p” sorption with ph, the experiment was conducted at the natural ph of the soils of each land use. lastly, equilibrium data were examined and fitted with the langmuir sorption isotherm equation (lópez-luna et al., 2019).statistical analysis el el e ck ckq q   1 max (2) where: qe (mg/l) = concentration of soil “p” adsorbed on the unit mass of adsorbent, ce (mgl -1) = concentration of soil “p” at equilibrium, qmax (mg/l) = maximum adsorption capacity of the soil based on langmuir equation, and k = langmuir equilibrium adsorption constant (lmg-1). 2.4. kinetics of soil chemical reactions under different land use types: many soil chemical processes are time-dependent (scheidegger and sparks, 1996). such a study helps to fully understand, the dynamic nature and interactions of plant nutrients with soils and to predict their fate with time. knowledge of the kinetics study is important to determine how rapidly reactions attain equilibrium and to infer evidence on reaction mechanisms. for the kinetic study of soils of different land uses, equilibration time was deduced from the kinetic trial and fixed at 5hrs. soil chemical reactions occur over a wide time scale ranging from milliseconds for some sorption reactions to even years (bereket et al., 2018; bera et al., 2006; lópezluna et al., 2019). to study the adsorption mechanism, the kinetics of soil “p” soprionadsorption was examined using pseudo1st order and pseudo 2nd order rate equations shown in equations (3) and (4) below. )exp1( )( 1tk et qq   (3) )1( )( 2 2 2 tqk tqk q e e t   (4) where: qt (mg/l) = amount of soil “p” adsorbed per unit mass of adsorbent at time t (hrs), qe (mg/l) = amount of soil “p” adsorbed per unit mass of adsorbents at equilibrium, k1(hr −1) = pseudo-firstorder rate constant, and k2 (min -1) = pseudo-secondorder rate constant. 3. results and discussion 3.1. status of selected soil properties under different land use types the mean values of selected soil properties of the soils of the three land use types are indicated in tables 1 and 2. the textural class of soils of forest land was clayey loam, whereas that of grazing and cultivated lands was clayey. the indication of clayey loam textural class in forest land is probably due to the presence of high organic matter in soil and the similarity of a textural class of clayey in grazing and cultivated lands may be due to similarity in the parent materials of the soils. soil bulk density in the forest land was higher than the remaining land uses (table 1). the lower & higher bulk density of soils in cultivated and forest lands may be accredited to the high som, porosity, and less soil disturbance in the forest land. relatively, the total porosit y was higher in forest land & lower in cultivated land. the fairly lower total porosity in soils of cultivate d land when compared to natural forest & grazing land probably interrelated to high soil compaction & loss of som may be conveyed on the intensity of soil management practices thereby subsequent decrement of porosity than soils of forest & grazing lands. soil ph is a major soil parameter that regulates most of the biochemical reactions taking place in soils. it also indicates the degree of the availability of crop nutrients and lime requirement of soils. as per the rating by jones (2003), soil ph values perceived in the three land uses were found to be strongly acidic soil. however, soil ph was relatively lower in cultivated land. depletion of basic exchangeable cations in crop harvest leads to a release of h+ ion to the soil solution and hence lowers the soil ph value in cultivated land than the remaining land uses. achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 32 table 1. mean values of selected physical properties of experimental soils land uses soil parameters sand (%) silt (%) clay (%) textural class bulk density (g/cm3) total porosity (%) forest land 24.72 40.12 35.14 clay loam 1.41 53.21 grazing land 19.35 35.15 45.15 clayey 1.39 52.45 cultivated land 22.18 27.41 50.41 clayey 1.38 52.07 table 2. mean values of organic matter, total n, c: n ratio and available phosphorus “p” content land uses soil parameters ph(h2o) organic carbon (%) total nitrogen (%) c: n ratio available phosphorus (mg kg-1) forest land 5.50 4.95 0.34 14.55 7.51 grazing land 5.39 4.63 0.27 17.15 6.03 cultivated land 5.27 4.21 0.22 19.14 5.67 the soils used for the present study recorded better percent soil organic carbon (oc) content for the forest land and lower in the cultivated land. the relatively better higher percent oc content in the forest land and lower percent oc in t h e cultivated land is attributed to plant litter fall which abundantly returns to the soil surface, thereby enhancing oc content in the forest land. the soil total n followed the same manner as that of the distribution of oc content. when an assessment is made among the land uses, the relatively lower organic oc and the total n in the cultivated and grazing lands could arise from the decline in om inputs due to the removal of biomass during cultivation and grazing. theref ore , land use changes from forest land to grazing and then to cultivated land have caused deterioration of soil oc and total n content on the upper soil surface. the distribution of soil c: n ratio followed the same manner as that of soil oc and total n contents except for minor differences among the land uses. as per the rating of cottenie (1980), the available “p” content of soils under the three land uses was succeeding for t h e medium range. the relatively l owe r available “p” content i n grazing and cultivated lands may be due to the lower status of soil oc content. 3.2. soil phosphorus “p” sorption binding energy (k) soil “p” sorption bonding energy (kl) values of the soil were highly affected by land-use types (table 3). the values ranged from 0.096 (lmg-1) to 0.167 (lmg1) where the relative minimum and maximum value was recorded from the soil of grazing and cultivated lands, respectively. the values of k for all soils were greater than 0.096 (lmg-1), suggesting that there is no danger of loss of “p” into the subsoil and the river water (mcdowell and sharpley, 2001). however, soil “p” sorption binding energy relatively varied among the land use types of the present study (figure 2.). 3.3. soil phosphorus sorption characteristics the “p” sorption data of soils under different land uses were plotted according to langmuir equations. the data showed a promising fitness with the langmuir equation (r2>0.986) for all land uses. the adjusted r2 values ranged from 0.9864 to 0.9966 for the langmuir, suggesting a good model fit. phosphorus sorption indices and correlation of the indices with the constant k were presented in table 3 and figure 2. soil “p” sorption capacity and binding energy to hold “p” were calculated from soil “p” concentrations at equilibrium and rates of sorbed “p” on unit masses of soil colloidal suspensions. in all three land uses, equilibrium “p” solution and per unit “p” sorption by soil colloids increased with the increment of soil “p” concentration. equilibrium soil “p” concentrations and “p” sorbed on soils of different land use varied from each other and at different levels of “p” solutions. as shown in figure 3 initially, at low “p” concentration, the achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 33 relationship was linear and at high concentration, it deviated from linearity. the linearity between equilibrium “p” concentrations versus the rate of final “p” concentration “p” after equilibrium was due to the large intermolecular distance between soil “p” anions, resulting in negligible mutual repulsion, and deviation from linearity designated that the binding strength of soil to “p” decreased with increase in soil superficial saturation with “p” (fernandes & coutinho, 1994; bera et al., 2006). the amounts of the final concentration of “p” sorbed by the soils after equilibriums of the three land use increased with an increase in the level of additional “p” in the soil solution. among the land uses, soils of cultivated land sorbed the highest amount of soil “p” after equilibrium at any level of added “p”, followed by those of forest and grazing lands. due to differences in the brutality of soil “p” sorption, the values of sorption maximum calculated from langmuir isotherms also differ among land uses. table 3. mean values of langmuir sorption parameters and r2 values of the regression analysis values of soil phosphorus, “p”, sorption characteristics and r2 value land uses qe (mgl -1) kl(lmg -1) regression equations r2 kqmax (lmg -1) 1/qmax forest 9.72 0.103 y=0.00071x+0.0069 0.9864 0.7313 7.10 grazing 9.83 0.096 y=0.0007x+0.0073 0.9873 0.672 7.00 cultivated 19.05 0.167 y=0.00069x+0.0039 0.9966 1.080 6.50 figure 2: fitness of the soil phosphorus “p” sorption isotherm to the langmuir equation figure 3: langmuir “p” sorption isotherms of soils of different lands uses y = 0.00071x + 0.0069 r² = 0.9846 y = 0.0007x + 0.0073 r² = 0.9873 y = 0.00069x + 0.0039 r² = 0.9966 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0 10 20 30 40 50 c /q e (m g l -1 ) c (mg l-1) forest land grazing land cultivated land 0 200 400 600 800 1000 1200 1400 0 10 20 30 40 50 f in a l c o n c e n tr a ti o n o f p a ft e r e q u il ib r iu m (m g /l ) rate of phosphorus concentration (mg/l) forest land grazing land cultivated land achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 34 3.4. soil phosphorus, “p”, sorption indices, and orption maximum (kqmax): regression coefficients (r2) of langmuir isotherm varied among the three land uses (table 3) and ranged from 0.9864 to 0.9966 for the langmuir isotherm. the soil “p” sorption behavior was described by the langmuir sorption model with a regression coefficient (r2 > 0.9864) observed for the soils of the three land uses (table 3). however, when appraisals are made among land uses, soils differed noticeably in sorption characteristics under the three land uses. it is indicated that higher values (r 2 > 0.9966) have better strength than the lower values. thus, the good fitness of the model was ascertained by witnessing the r2 values. the highest mean value of the product of biding energy and sorption maximum (kqmax) was recorded in the soil of cultivated land (1.08 lmg-1), followed by that of the forest land (0.7313 lmg-1), while the lowest was recorded for the soil of grazing land (0.672 lmg -1) (table 3). the observed differences in the product of the binding energy and sorption maxima among the three land uses were most likely due to the differences in the amounts and nature of “al” and “fe” components present in the soils. in addition, the fairly higher product of biding energy and sorption maximum (kqmax) in the cultivated lands could be partly due to the lack of residual effect of the application of external soil “p”. this indicates that the studied soils might not be suitable for agricultural crop production. the relatively low production of the binding energy and sorption maxima in the grazing land could be due to better organic matter in the soils of this land than in the soils of cultivated land. almost all the soils had sorption maxima ranging from (0.672 to 1.080 lmg 1), indicating that the soils have different sorption levels at different land uses. 3.5. kinetics study of soil phosphorus adsorption to examine the adsorption mechanism, the kinetics of soil “p” adsorption was analyzed using the pseudo1st order and pseudo2nd order rate equations described in equations (3) and (4) given above. the plot fit to the experimental data of soil “p” adsorption is given in figure 5 and rate constants are summarized in table 4. the statistical criteria used for estimating the goodness-of-fit of the models to the experimental data were the coefficients of determination (r 2). the kinetic data show that qe.exp and qe.cal are closer, and the r 2 values are comparably lower and almost similar to the pseudo1st order kinetic model than the pseudo 2nd order model (table 4). however, the r 2 values for the pseudo-second-order are high enough to fit the model. moreover, the soils of the forest lands are very high enough to fit the model among the different land uses. the adsorption of soil “p” for this study is better described by pseudo 2 nd order kinetics, the fairly higher (r 2 =0.9898) value of the pseudo 2nd order kinetics recorded for the soil of the forest land, and the lower (r 2 =0.6999) value was recorded in the grazing land. 3.6. effect of contact time: the effect of contact time between the originally sorbed and after equilibrium “p” of the soil of the forest, grazing, and cultivated lands is displayed in figures 4 and 5. the adsorption at the beginning was fast at 1 hour under each land use type. after 180 minutes, there was no significant adsorption and it was almost static. thus, 180 minutes of contact time is considered to be the equilibrium contact time for the batch study. at 320 minutes, which was the end of the adsorption, the experiment is not substantial to increase the time above 320 minutes. that is, there is no more soil “p” expected to be sorbed in the soils. table 4. pseudo1st order and pseudo 2nd order kinetic model of soil phosphorus adsorption land uses qe exp.( mmol/kg) k1, k2 (min -1 ) qe (mmol/kg) pseudo-1st order pseudo-2nd order r 2 r 2 forest land 9.72 0.103 9.84 04674 0.9898 grazing land 9.83 0.096 10.15 0.4674 0.6999 cultivated land 19.05 0.167 20.13 0.4675 0.7911 achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 35 figure 4: plot of pseudo-1st order kinetic model of soil “p” adsorption under different land uses figure 5: plot of pseudo 2nd order kinetic model of soil “p” adsorptions in different land uses 4. conclusion the results of the study revealed that soil ph under the three land uses fell under strongly acidic soil. however, significant differences in “p” sorption capacity and sorption characteristics were witnessed within land uses. the difference in soil “p” sorption characteristics under soils of different land uses brought variation in values of soil “p” binding strength, showing that higher values (r2 > 0.9864) obligate better soil “p” binding strength. the highest mean value of the product of biding energy and sorption maximum (kqmax) was recorded in the soil of cultivated land (1.08 lmg-1), followed by that of the forest land (0.7313 lmg-1), while the lowest was recorded in the soil of grazing land (0.672 lmg-1). thus, the good fitness of the model was ascertained by witnessing the relatively higher r2 values. langmuir model was found to be effective in describing the “p”-sorption patterns of soils of different land uses. the kinetic data indicated that the concentration of soil “p” adsorbed on the unit mass of adsorbent (qe) of soil under different land uses are closer to each other, and the r 2 values are comparably lower and nearly referents for the pseudo1st order kinetic model than the pseudo 2nd order model. the “p” sorption kinetics in soils was fast in the first 120 minutes and then showed no variation with the increase of the contact time. achalu chimdi. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 36 reference achalu, c. 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(2005). path and multiple regres sion analyses of phosphorus sorption capacity of soils. soil sci. soc. am. j., 69:96-106. 23 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper mapping faults around adama town: implication for future earthquake triggering potential asfaw erbello*, hassen shube adama science and technology university, school of applied natural sciences, department of applied geology, adama, ethiopia * corresponding author, e-mail: asfaw.erbello@astu.edu.et abstract extensional tectonic environments mainly reflect normal fault induced geomorphological features. the study area (adama and its surrounding) is located in the northern main ethiopian rift (mer) where nne-ssw striking extensional related normal fault features are common. aim of this study is to integrate structural and geomorphological features of fault scarps of the area to infer their earthquake triggering potential. a combined method of fault plane analysis and stream profile index approach used to evaluate faults activity of the study area. kinematics of five selected sites structural data analyzed and integrated with geomorphological results. all sites averaged fault plane analysis revealed n 112° e directed tectonic stress of the area. the result is statistically similar with the current stress inferred from geophysical monitoring (~ n 105° e). this geometrical coincidence in stress direction may result reactivation of previously formed major faults of the area. the result shows minor deflection to the south which could be resulted due to crustal strength heterogeneity and /or local stress change. morphological analysis using stream profile index indicate active fault signatures such as knick points. these signatures are mainly common in the west of the study area. integration of structural and geomorphological data mainly from the western side of the town further confirms active fault characteristics which may result rupture induced earthquake occurrence along these fault planes. pilot study on ground cracks around the town shows a significant relationship with faults of the area. this correlation indicates the current tectonic stress of the area has a significant control on the frequently occurring ground cracks in the area. keywords: fault kinematics, tectonic stress, paleo-stress, ground crack, knick point. 1. introduction surface manifestations of faults in tectonically active regions are common morphological expressions. morphological expression of these active faults could be varied, mostly based on the faults activity, lithology affected by faulting and climatic condition of the area (lifton & ghane, 1999). the study area located in the northern mer which is part of the east african rift system (ears). the mer contains a series of active rift zones with associated effusive to explosive volcanic products concentrated along the general trend of the rift. the mer traditionally classified into three segments based on the relative intensity of volcano-tectonic activities and faults architecture (agostini et al., 2011). these are southern mer, middle (central) mer and northern mer. the boundary which divides each of them is delineated in different positions by different researchers. petrologists and structural geologists classified the boundary based on the intensity of volcanic products, their petrographic characteristics and structural features (agostini et al., 2011) while geophysicists use geophysical anomalies to classify each of the sections (keir et al., 2006a). the whole http://www.ejssd.astu.edu/ mailto:asfaw.erbello@astu.edu.et asfaw erbello & hassen shube ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 24 mer which started to develop in miocene time, is part of the ears and comprises a series of rift zones extending over a distance of about a thousand kilometer from the afar triple junction down to the south (boccaletti et al., 2000). a number of rift related episodic volcanic products distribute throughout the rift sector and rift shoulder in the region (rooney et al., 2018). faulting in the region characterizes different geometrical features in the different sectors of the rift (corti, 2009; agostini et al., 2011; erbello et al., 2016). the different geometrical features of the faults in the region developed due to a change in stress direction (bonini et al., 2005) or a constant continuous stress with the influence of pre-existing weak zones (corti, 2009; erbello et al., 2016) or related northeast-southwest strike slip extension throughout the history of rifting in the region (muluneh et al., 2015). geodetic and seismic data observations from the different segments of the mer which is assumed to be controlled by long term nubia-somalian plate motion constrain an average extension direction between ~n900e and ~ n 1050 e (keir et al., 2006a; stamps et al., 2008; saria et al., 2014). structural features developed due to either of the above stress orientations are classified in to marginal faults and axial faults (corti, 2009). majority of structures around the study area (axial faults) are characterized as woniji fault belts (abebe et al., 2007) with nne-ssw general orientation. the area is situated along one of the active right stepping en echelon arranged gedemisa-boset magmatic segment in the northern mer. considering the area location within the mer specifically in the northern mer (figure 1), it is believed that the region is both seismically and volcanically active. one of the most commonly known structural effects of earthquake is formation of fractures which will progress to faults. repeated earthquakes along a fault plane will result a cumulative slip with a significant vertical displacement and well preserved fault scarps mark most recent earthquakes (benedetti et al., 2014). it is suggested that larger fault scarps such as the adama fault scarp form through a long term continuous earthquake generations. in tectonically active regions; morphological features such as across fault scarp stream profiles reveal information about recent faults activity (hack, 1973). faults reactivation could be significantly influenced by geometrical relationship between their orientation and current kinematics of the region. studying local faults kinematics and their morphological characteristics has a significant contribution to understand earthquake potential and earthquake induced geohazard in an area like adama town and its surroundings where infrastructure development and population density is drastically increasing. this project aimed to study kinematic and morphological features of faults around adama town to evaluate their future earthquake triggering potential through comparison with the current stress orientation of the region. figure 1: location map of the study area. 2. methods and materials methods adopted for this study includes a morphological investigation of the area using high resolution google earth images and satellite images using arc gis techniques. stream network map of the area is generated from the shuttle radar topographic mission (srtm, 30m resolution). based on the characteristics of stream networks extracted from digital elevation model (dem), we choose stream profile networks flowing across the strike of faults to investigate their slope gradient variation. for this approach we used hacker profile and sl index analysis of streams. the longitudinal river profile is a curve, which represents the variation of elevation with the downstream distance of a river (hack, 1973). asfaw erbello & hassen shube ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 25 sl= (δh/δl) l where δh/δl is the channel gradient for a particular segment (δh ¼ difference in elevation, δl ¼ length of segment); l is the total length of the channel from its source to the midpoint of the particular segment. knick points are mostly associated with high values of sl index in comparison to the adjacent segments. in general, the segments with high sl index correspond either to change in lithology or an active fault (hack, 1973). in a profile, a graded river is approximated by a straight, inclined line (hack & young, 1957). however, ungraded river profiles are mostly marked by a concave or convex upwards segments, depending on the degree of erosion and rate of uplift. from this slope gradient along the stream, we evaluated the activities of some selected faults. in addition to these all, standard fault attitude measurement data from five sites distributed around adama town (figure 3) collected to compare with the current tectonic force of the region. figure 3: distribution of fault plane measurement sites overlay on hill shaded image of a 30m resolution dem. 3. results and discussion 3.1. structural features of adama area structures exposed in this area varied both in length and orientation. most of structural features show closely related geometrical characteristics. the general orientation of structures range from n 100 w to n 250 e strike. dip of faults also varied from 650 -700 e. most of structures dip to the west and east with the range of dip amount indicated above. few east-west oriented structures identified in the south east of the study area. this east-west oriented structures mainly link larger ne-sw oriented structures. about 104 fault plane and fracture plane measurement data collected from five sites. the sites are geographically distributed to all directions of the study area where accessible fault plane measurements available. high displacement; longer faults are the characteristics of the western side of the study area. orientation data of faults plotted on a stereographic projection (figure 5). overall strike of all the faults plotted show n 220 e orientation. the shorter faults are linked by some east-west oriented much shorter faults. collapse of a ridge in the east of the adama town follows the general orientation of faults in the area. the southern part of the town and its surroundings are characterized by closely spaced parallel faults. scoria cones and volcanic ridges are systematically distributed in association with faults in this area (figure 4). in addition to faults, there are smaller to larger ground cracks oriented parallelsubparallel with faults. as like the faults in the west of the town, the faults in this part forms narrow horst and graben structures. further comparison of faults geometry, with the western side (site one), faults in this area are shorter both in length and vertical displacement. some of the faults in the south and north of the town identified as propagating towards each other and closer to link within the town which could be a potential site for stress overlap. faults in the north of the town are few in number, but longer in length. some of the faults in this section are identified as propagating towards to the north of the town. an average extension direction of senw or ~ n 1120 e (figure 6) inferred from kinematic analysis. joints in the area are mostly two systems of joints where one is striking e-w and the second is asfaw erbello & hassen shube ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 26 perpendicular to the first and parallel to the strike of faults in the area. figure 4: structural map of the study area (adama and its surroundings) overlay on a 30 m resolution dem modified from (abebe et al., 2007). figure 5: calculated poles (triangles) plotted from strike and dip measurement data (great circles) from representative sites 1, 3 and 5 (a, b and c respectively). the last plot (d) shows overall calculated poles from all sites. figure 6: calculated paleo stress direction on a stereographic projection. small arrow emerging from red circles indicate paleo stress for each of measured fault data (outliers removed). the bigger arrow indicate an average paleo stress direction for all measured and analyzed fault data. 3.2. morphological features of the study area geomorphological features of the study area resulted from fault morphology and volcanic product pileups (figure 7). stream network characteristics are significantly influenced by quaternary faulting activities of the area. stream profile index sl is a powerful tool to investigate tectonic, climate and lithological impact on stream flow nature. most of streams flow pattern in the region indicate strong relationship with the pattern of structures (figure 9). majority of streams are flowing parallel with the strike of faults. there are only little number of streams flowing across the strike of faults. the higher values of sl identified from each of across fault flowing streams and each of the points were also verified in the field. majority of fresh fault scarps outcrop reveal immature stream profile signature. this is one of atypical characteristics of active fault features. other common feature is fault overlap zones where two en echelon arranged faults are propagating towards each other. in active region like our study area; such feature zones are areas where stress overlap (figure 8). a cumulative propagating stress could result an earthquake and associated earthquake hazard such as landslide because of the area contains highly fractured weak rock fragments. asfaw erbello & hassen shube ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 27 figure 7: morphological expression of fresh fault out crops (inset figure). figure 8: overlapping fault characteristics: (a & b) fault overlap nature and stress drop envelop models modified from(gupta a. & scholz h, 2000) and (c & d) identified fault overlap zones and their characteristics in the study area mainly in adama town. 3.3. ground cracks and its tectonic relationship ground crack feature is a common ground failure characteristic in the rift valley of ethiopia. even though the cause of these ground cracks not yet identified in scientific reasoning, but it is becoming a critical problem in the rift valley regions of ethiopia such as adama area. field work conducted to investigate these ground cracks in adama and its surroundings to check their relationship with the structures of the area. strike measurement of ground crack data performed using high resolution google earth image of the area. these ground cracks most commonly form in the rainy season. intensity of their spatial distribution, their geometrical parameters such as crack width and crack length are also asfaw erbello & hassen shube ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 28 variable. surface exposure of reworked volcanic and soil material thickness varies in the north and south directions of the town. this variation indicates cohesion variation in the area. this could be one of the reasons for the spatial distribution variability of ground cracks around adama town. in addition to these, collected and analyzed ground crack orientation data from the different parts of the town reveal a significant contribution of tectonic activity of the area. the average orientation of ground crack measurement data obtained from stereo net plotting is n 130 e (figure 10). figure 9: fault controlled stream flow patterns and elevation versus distance profile of across fault flowing streams. red dotted vertical lines (a, b, and c) indicate knick points which indicate active fault signatures. asfaw erbello & hassen shube ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 29 figure 10: ground cracks orientation plot and an example of a 20 m wide ground crack between two parallel faults. 4. conclusion along the strike of the mer, it has been recognized that seismic and volcanic activities are significantly variable. the northern mer is one of the most recognized volcanically and seismically active region. our structural data analysis, comparison with geophysical data and integration with geomorphological feature suggest the following: 1. overall paleo stress analysis of fault plane measurement data shows n1120 e stress direction. it has a minor deflection with respect to the regional geophysical data n1050 e (stamps et al (2008). it is interpreted that the minor deflection could be due to local stress variation, local crustal heterogeneity and the area is an overlap zone between central mer and northern mer. this close relationship with the current stress in the region can cause slip along the faults in the area to trigger an earthquake. 2. geomorphic investigation through drainage analysis indicates, majority of streams are flowing parallel to the strike of the faults which indicate the scarp is still fresh for steam incision. limited number of stream profile analysis indicate also fault scarps mainly the western margins are active. this agrees with the structural data. 3. pilot major ground crack geometrical analysis reveal n 130 e strike direction. it clearly indicate close relation with the local and regional stress orientation. this suggests that local and regional tectonic stresses have significant contribution in ground crack formation in the region. acknowledgment the authors would like to acknowledge adama science and technology university research affairs for the financial support. reference abebe, b., acocella v., korme, t., ayalew, d. 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(2014). present day kinematics of the east african rift. journal of geophy research, doi 10.1002/2013jb010901. stamps, d. s., e. calais, e. saria, c. hartnady, j. m. nocquet, c. j. ebinger, and r. m. fernandes. (2008). a kinematic model for the east african rift. geophys. res. lett, doi 10.1029/2007gl032781. 1 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 production of bio-diesel from cucumis sativus seed oil involving crystalline manganese carbonate – a green (nanosized) catalyst k.s.k. rao patnaik1, melakuu tesfaye alemea1, a. sunil2, y. rajeshwer rao3 1 adama science and technology university, school of mechanical, chemical and materials engineering, dept. of chemical engineering, p.o.box.1888, adama, ethiopia e.mail:drkskrao@gmail.com 2 dept.of chemical engineering, osmania university, hyderabad, india 3 department of chemistry, rajiv gandhi university of knowledge technologies, iiit basara-504 107, telangana state, india abstract this paper focuses on the production of bio-diesel from low cost feed stock cucumissativus seed oil using mnco3 as a green (nanosized) catalyst through transesterification process and investigating the effects of process parameters on bio-diesel yield. the optimum parameters for maximum bio-diesel yields were found to be methanol/oil molar ratio of 1:1, catalyst concentration of 1 wt% of oil, at the temperature of 65 ° c and reaction time 3 hours (180 min). the maximum bio-diesel yield at the optimum condition was 86%. crystalline manganese carbonate was found to be environmentally friendly, easy to handle and non-corrosive green catalyst for the production of biodiesel from cucumber seed oil. the enhancement of the parameters are possible because of the nano nature of the catalyst used. the results demonstrated high potential of producing economically viable biodiesel from low cost feed stocks with proper optimization of the process parameters. keywords: manganese carbonate, cucumissativus seed oil, methanol, transesterification, bio-diesel. 1. introduction bio-diesel has been a promising alternate fuel during the past decade as a renewable source. it is a biodegradable from transesterification of vegetables oil with alcohol has been accepted for use in blends with conventional petroleum fuel for transportation applications [14]. soybean and rapeseed are common feedstock for biodiesel production in usa and europe respectively. likewise, palm is being exploited in south east asia [5]. in order to explore additional patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 2 © adama science & technology university https://ejssd.astu.edu.et oil resources (non-edible oils), the study on potential of cucumber (cucumis sativus) seed oil as bio-diesel resource is reported here. the potentiality of crystalline manganese carbonate as a catalyst has proven worthy for the bio-diesel yield. this was possible because of its nano nature. bio-diesel fuel is made from vegetable oils, animal fats, and microbial oil (algae, yeast, bacteria, and fungi).the most common method in the production of bio-diesel is the transesterification reaction, where the triglycerides present in oil react with monohydric alcohol in the presence of a catalyst, such as sodium hydroxide, sodium methoxide, potassium hydroxide, crystalline manganese carbonate and potassium methoxide [1-4, 6]. bio-diesel synthesis using solid catalysts like manganese carbonate, instead of homogeneous catalysts like sodium hydroxide, could potentially lead to cheaper production costs by enabling reuse of the catalyst [7-13]. in the present study, attempt has been made to convert cucumissativus seed oil to fatty acid methyl esters (fame) using crystalline manganese carbonate a low cost, non-corrosive and green catalyst. this brings about 86% conversion of oil to fame. transesterification (fig 1) is the chemical reaction between triglycerides and alcohol in the presence of the catalyst to produce monoesters. the heterogeneous manganese carbonate base catalyst is active for high molecular weight alcohol achieving conversion to 90% and produces neither corrosion nor emulsion making it easier to separate the product obtained [2]. in literature, many attempts have been made for search of new effective catalysts and feed stocks using transesterification reaction, for the production of bio-diesel. m. arunkumari, et al. (2014) [1], patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 3 © adama science & technology university https://ejssd.astu.edu.et have concluded that crystalline manganese carbonate gave higher yield than zinc oxide when producing bio-diesel from pongmiapinnata and guizotia abyssinica feed stocks. fig.1.transesterification of triglycerides with alcohol 2. materials and methods 2.1. materials: the cucumis sativus seed oil, crystalline manganese carbonate and methanol were purchased directly from the laboratories. analysis of cucumber oil: cucumis sativa seed oil (cucumber oil) is subjected to gas chromatography to determine the composition. the samples are analyzed with a shimadzu gc-2010 gas chromatograph, equipped with a split less injection system. helium is used as a carrier gas. instrument conditions are maintained: column oven temperature 75°c, injection temperature 250°c, flow control mode in linear velocity with 92.5 cm/sec, total flow 61.2 ml/min, column flow 5.42 ml/ min, purge flow 1.5 ml/min, pressure 100 kpa, whereas the split ratio 10.0. samples are prepared for analysis by adding approximately 0.05 gof oil phase to 5 ml of n-hexane. about 1ml of this mixture is put in to the gc auto sampler vials. two micro liters of the sample are injected into the column. the obtained results for fatty acid compositions of cucumis sativa seed oil (cucumber oil) are shown in table 1. cucumis sativa seed oil (cucumber oil) has the major fatty acids which are linoleic, stearic, oleic and palmitic acids. 2.2. experimental procedure: the cucumissativus seed oil (cucumber oil) is taken in the reaction flask and heated at 50°c. the mixture of catalyst in methanol with different concentrations is used for the conversion of patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 4 © adama science & technology university https://ejssd.astu.edu.et cucumissativa seed oil to fame. transesterification reactions are performed in a 150 ml round bottom flask with a reflux condenser, stirring is provided by a magnetic stirrer. the stirrer is set at a constant speed throughout the experiments. initially, the oil was heated at a desired temperature. the methanol and catalyst mixture was added to the round bottom flask containing oil. at that point, the reaction is kept under reflux conditions. the formation of methyl esters from cucumber oil is monitored by thin layer chromatography. the methyl esters are washed with distilled water and concentrated under vacuum to afford fame. fig.2. schematic diagram of the experimental setup catalyst analysis: in the present study, xrd and sem analysis of manganese carbonate is reported (fig. 3 & 4). recovery of catalyst: in the present work, the manganese carbonate catalyst is recovered by filtration and washed with 80°c distilled water 4-5 times. then the catalyst is dried at 50°c for 35 hours in the hot air oven. after the complete drying the catalyst is used in the transestrification reaction. the efficiency of the catalyst is 95%. the catalyst is still patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 5 © adama science & technology university https://ejssd.astu.edu.et efficient even after seven successive runs shown in table 2. table 1. fatty acids cucumissativa seed oil (cucumber oil). fatty acids cucumber oil % palmitic(c16/0) 11 stearic(c18/0) 7 oleic(c18/1) 14 linoleic(c18/2) 68 table 2.the efficiency of the catalyst after seven successive runs catalyst quantity 1% cucumis sativa methyl esters yield (%) first use second third fourth fifth sixth seventh 95 95 94.5 94.5 94 94 93.5 figure.3: xrd of manganese carbonate. figure 4:.sem image of manganese carbonate 3. results and discussion effect of methanol/oil molar ratio: in the present work, transe sterification of cucumissativus oil with 1% mnco3 catalyst using alcohol /oil ratio between 1:1 and 5:1 is carried out; it is observed that the ester conversion increases patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 6 © adama science & technology university https://ejssd.astu.edu.et with the decrease in molar ratio up to the value of 1:1. the highest bio-diesel yield achieved at 1:1 molar ratio is 86% in 180 min. the results are depicted in fig.5. fig.5. effect of methanol/oil molar ratio effect of catalyst quantity: the highest bio-diesel yield 86% is obtained at 1wt% catalyst in 180 min. further increases of catalyst quantity shows decrease in biodiesel yield and add extra cost, since the catalyst needs to be removed from the reaction mixture after the reaction. the effects of mnco3 quantity on transe sterification are presented in figure 6. at 1% of the catalyst the bio-diesel yield is 86%. effect of temperature: the reaction temperature effect on the bio-diesel yield is studied in the range of 28-65°cat atmospheric pressure. the maximum yield is achieved at 65°c 180 min. the methanol to oil molar ratio was 1:1 and the catalyst concentration is 1% in all the experiments. the temperature dependence of biodiesel yield is presented on fig.7. fig.6. effect of catalyst quantity fig.7. effect of reaction temp. patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 7 © adama science & technology university https://ejssd.astu.edu.et effect of reaction time: experiments are carried out at various speeds between 30-180 min. the experiments showed that conversion of cucumis sativa oil to bio-diesel yield of 86% is achieved within 180 min at reflux condition. however, the reaction is carried out at the temperature close to the boiling point of methanol (60-70°c) at atmospheric pressure for a given time. the effect of reaction time on bio-diesel yield is reported in fig.8. fig.8. effect of reaction time 4. conclusions the studies on crystalline manganese carbonate as a catalyst for bio-diesel production are cited in the literature as a potential catalyst. but the reason behind the potentiality may be because of the nano nature. the results show that at 1:1 ratio of methanol to cucumissativusoil at 65°c gives the highest yield. the bio-diesel yield conversion increases directly with decrease in methanol quantity at different catalyst to oil ratios. using manganese carbonate (1% wt.) as the catalyst for cucumis sativus oil transesterification with methanol, 86% yield of bio-diesel is achieved. the crystalline manganese carbonate (nano sized) is found to be an alternative, green and heterogeneous catalyst for the production of bio-diesel. acknowledgement the authors would like to thank the principal, university college of technology, osmania university, hyderabad, india for providing research facilities. the authors are also acknowledge the president, adama science and technology university and dean, patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 8 © adama science & technology university https://ejssd.astu.edu.et somcme, dept. of chemical engineering, adama, ethiopia for providing computer facilities. references [1] m arunakumari, k.s.k.rao patnaik, y rajeshwer rao (2014), “production of biodiesel from pongmiapinnata and guizotiaabyssinica seed oil using crystalline manganese carbonate (mnco3) and nano zinc oxide (zno) – a green catalyst”, international scientific journal of environmental science, vol. 3, pp. 14-20. 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[7] s. furuta, h. matsuhshi and k. arata, (2004) “bio-diesel fuel production with solid superacid patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 9 © adama science & technology university https://ejssd.astu.edu.et catalysis in fixed bed reactor under atmospheric pressure”, catalysis communication, vol. 5, no. 12, pp. 721-723. [8] k. narsimharao, a. lee and k. j. wilson, (2007) “catalyst in production of bio-diesel: a review”, biobased materials and bioenergy, vol. 1, no. 1, pp. 1-12. [9] xin deng, zhen fang, yun-hu liu, chang-liu yu (2011), “production of bio-diesel from jatropha oil catalyzed by nanosized solid basic catalyst”, energy, pp. 1-8. [10] mulatu geleta, stenstymne, tomas bryngelsson, (2011) “variation and inheritance of oil content and fatty acid composition in niger (guizotia abyssinica)”, journal of food composition and analysis 24, pp. 995-1003. 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[13] p. pramanik, p. das, p. j. kim, (2012) “preparation of biofuel from argemone seed oil by an alternative costeffective technique”, fuel 91, pp. 81-8 1 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper microbial qualities of drinking water and its public health implication: the case of adama town, ethiopia keredin temam siraj1,*, p.v.v. prasada rao2, ch. durga prasad2 1adama science and technology university, department of water resources engineering, adama, ethiopia 2department of environmental sciences, college of science & technology, andhra university, visakhapatnam-530 003. * corresponding author, e-mail: keredin.temam@astu.edu.et or keredin2009@gmail.com abstract this study is an investigation on microbial quality of drinking water and public health assessment in adama town during june to december 2016. accordingly, seven strata were formed from the total distribution system of municipal drinking water supply starting from the raw water intake up to community storage. public health was assessed by using primary and secondary data. the presences of the indicator organism (tcb, fcb and e.coli) were considered for drinking water quality vis-a-vis public health. a multi-tube fermentation technique was employed to evaluate the indicator organism and the result was expressed in the mpn. residual chlorine were evaluated at each stratum. 52 sample per month were tested and totally 312 samples are tested entire the study period. the findings revealed that 26.28% of samples examined were positive for tcb, 9.29% for fcb and 0.96% for e. coli. 30% of the e.coli contamination was due to unhygienic handling of water after collection. the result of the present study showed that 27.06% of cases admitted for laboratory test in the government health care centre were either waterborne or water related diseases. among those positive samples for indicator organism, 79.89% of them were confirmed with the physical address of patients. quality of drinking water alteration in the study area is mainly at home due to unhygienic handling. furthermore, illegal extension, infrastructural expansion, low initial concentration of chlorine, aging of pipeline, distribution by rotation and lack public awareness in general are the other main reasons for water quality impairment. these factors have to be considered to maintain public health in the area by concerned bodies drinking water provider and user. keywords: adama, indicator organism, multi tube fermentation techniques, public health and waterborne diseases. 1. introduction maintaining public health was highly dependent on the potability and accessibility of water. however, about 663 million people are living with no access to potable water worldwide. of which 50% of the people live in sub-saharan africa countries (who/unicef, 2014). lack of accessibility and potability of water has a dual effect on public health. it is causing diseases either due to an unhygienic condition in the community or/and causing diarrhoeal diseases (hunter et al., 2010). the report shows that currently the majority of diarrhoea and related deaths around the world are either due to lack of accessibility to safe drinking water or personal unhygienic condition (who/unicef, 2014). diarrhoea emanating from unsafe drinking water is responsible for causing 17% of the deaths of ≥5years children’ in most of developing countries (clasen et al., 2007). in another report, diarrhoeal diseases are the second leading cause of deaths of ≥5 year’s children. similarly, diarrhoea kills half million under five children every year in ethiopia and it is the second largest killer next to pneumonia. in which about 90% cause of diarrhoea is the unhygienic condition, lack of http://www.ejssd.astu.edu/ mailto:keredin.temam@astu.edu.et%20or%20keredin2009@gmail.com keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 2 access to safe water and improved sanitation (gebru et al., 2014). according to water aid report, about 43 million people lack access to safe drinking water, 71 million lack access to improved sanitation and 28 million people use open defecation in ethiopia (water.org, n.d.). the improvement of social services and public health are dependent of both potability and accessibility of water (calow, ludi, & tucker, 2013). that is why water service underpins were considered as one of the priority area for sector growth enhancing in ethiopian’s growth and transformation plan i (gtp, 2011-2015). the achievement of 98.5% nationwide for water supply access coverage was planned in gtp-i. however, gtpi 4th year report shows that 76.7% were achieved. adequate and safe water provision is crucial issue for the social service improvement, public health and economic growth in multiple sector in general. furthermore, the study area is exposed for number of factors limiting potablity and accessibility of water such as industrial expansion, population growths and others. therefore, monitoring existing water quality in the area is very important to maintain public health and other developmental activity (calow, ludi, & tucker, 2013). accordingly, the present study aimed to evaluate microbial quality of drinking water, identify the point of deflection of water quality among the formed strata and assess the rate of waterborne and water related diseases in the study area. among powerful environmental determinants of health, drinking water quality is crucial in maintaining public health. maintaining drinking water quality has been continuing as a key pillar for more than a century and expected to continue as a basic foundation for prevention and control of waterborne diseases. though water is the most essential for life, it can easily transmit diseases entire the globe. among the most prominent waterborne diseases, diarrhoeal diseases are most predominant with an estimated annual incidence of 4.6 million episodes resulting in 2.2 million deaths every year (kirk et al., 2015). the health report of the adama town health office shows that in the last five years alone 72911 people are infected with diarrhoea while 80078 and 44545 people are affected by dyspepsia and pneumonia respectively. the above three diseases are among the top ten diseases in the area with expected cause of unsafe water uses or unhygienic condition. mostly, waterborne diseases transmitted either due to contamination of the catchment areas of human and animal faeces, leakages in the distribution system and/or unhygienic handling of water storage at household (eisenberg et al., 2002). observations in the present study area showed that high rate of leakages in distribution pipes, illegal extension, line breakage due to expansions and aging and about 20% of water loses due to leakage drinking water distribution system. these observations helped the present study to identify the strata that have more potential for contamination of waterborne and water related diseases in the area. this may be either drinking water source or recontamination of distribution system seems to be the cause of contamination vis-a-vis waterborne and water related diseases. diarrheal diseases such as cholera and others like guinea warm, typhoid fever, hepatitis a, hepatitis e and dysentery are some of waterborne and water related diseases (website, n.d.). despite the fact that there are disparities on the available data for the mortality caused by waterborne and water related diseases in different years, still 3.4 million deaths were recorded every year by water related diseases (ashbolt, 2004; who, 2013). waterborne and water related diseases such as typhoid fever, which is bacterial infection due to contaminated water (d’agostino et al., 2008), hepatitis e due to contaminated drinking water by virus (“hepatitis e vaccine: who, 2015), guinea worm which is parasitic diseases due to unsafe drinking water, giardiasis which is parasitic diarrheal illness commonly caused by contaminated drinking water (moriyama et al., 2011; cdc, 2010). cholera one of most common diarrheal diseases, gastroenteritis, dysentery, diarrhoea, cyclosporiasis and many others were identified scientifically as they are due to water (d’agostino et al., 2008). the study aimed to evaluate a microbial quality of drinking water, to measure the rate of waterborne and water related diseases and to recommend concerned body to maintain public health. un millennium development goals (unmdg) 4 and 7 are aimed at reducing child mortality rates by 2/3 and ensuring clean drinking water and basic sanitation to all by 2015. however, sub-saharan africa and south asia are remained hotspots (ntouda et al., 2013; jeffrey et al., keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 3 2008). acute respiratory infection (ari) and diarrheal diseases (dd) are the two leading causes of death worldwide. every year about 4.4 and 3.1 million children under 14 year deaths are recorded mostly by pneumonia and dd respectively. however, deaths due to diarrhoeal diseases reached 41,287 per annum in ethiopia amounting 6.87% of the total deaths, making the country 35th ranked in the world by diarrhoeal deaths (who/unicef, 2014; website, n.d.). cholera still occurs as an epidemic in drought-affected areas due to contaminated water is in use (jeffrey et al., 2008). the process and technology to evaluate all pathogenic microorganisms in water are so complex and expensive. hence, indicator micro-organisms were considered to identify the presence of the pathogenic organisms in water (taubeneck, 1980). the history of using an indicator organism as an indicator of water and sanitary quality is traced back to 1888 when von frestch basically investigated bacteria, such as klebsiella pneumonia's and k. rhinoscleromatis that were found in faeces (geldreich, 1996). therefore, in the study, indicator organisms have been used as indicator of water quality and potential exposes to waterborne and water related diseases. among available and widely applied methods of microbial quality of water, multiple tube fermentation techniques and membrane filter technique are most common. though membrane filter technique is most advantages than multiple tube fermentation technique, it is not applicable all types of water (bartram & ballance, 1996). therefore, in this study multiple tube fermentation technique was adapted. e.coli, total coliforms, faecal coliforms, heterotrophic plate count, enterococci, faecal streptococci, campylobacter, pseudomonas aeruginosa, staphylococcus aureus and/or salmonella are among types of test supposed to be conducted in microbial quality of water samples. of which e.coli, total coliforms and faecal coliforms were tested as indicator organism. 2. methodology 2.1. description of the study area adama town is located in the central parts of ethiopia, at geographical location of 8° 27' 54" up to 80 35' 7" n and 39°13' 5"e up to 39°19' which is 99km away from the capital city of ethiopia to the south east of the country (figure-1). the urban area of the town spread over 30 km2. however, the town with included parts of some rural area for water provision covers a total of 968.27 km2 and bordering with lume and boset districts, and arsi zone. the town found within an altitude of 1500-2300m above sea level. the mean annual minimum and maximum temperature of the study area is 14℃ and 33℃ respectively and yearly minimum rainfall is 808 mm. the district situated in a sub-tropical agro-climatic zone (oromia regional state, 2011). adama is one of a highly populated area in the eastern shoa zone. the total population of adama district is estimated at 201,110 for 2016 with 52:48 female to male sex ratio (ethiopian central statistical agency, 2016). 2.2. drinking water provision and treatment (dwpt) antiquity of the adama water supply begins with the water service given by the former ethiopian electric light and power authority (eelpa) which started by drilling about 10 boreholes at the place called melka hidda (awssse, 2015). currently, adama town receiving potable water from two sources; surface water as the main source and groundwater as the complementary source. adama municipal drinking water is drawn from awash river. the establishment of adama water treatment, known as koka drinking water treatment plant (kdwtp) is positioned left to awash river just after koka hydropower dam around 10-15 km downward side, in the western part of the town. the treatment plant was designed to harvest 330l/s. the treated water is pumped from kdwtp and it travels 1015 km to reach the first of two reservoirs known as “lugo-reservoirs”. the second couple reservoirs known as 02 kebele reservoirs is stationed at a distance of 5-10 km from “lugo-reservoirs” at gelawudios, and the treated water is collected here by gravity. one of the reservoirs in the second group is for emergency purpose, thus sparingly used; hence, the other one distributes water to three other reservoirs in the town and serves as the centre of distribution. the treatment plant is recently upgraded to bridge the gap between demand and supply, as a result of increasing population and industrial expansion (fortune, n.d.). nine reservoirs are available in different place with total capacity of keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 4 13,700m3 at a time. of which six reservoirs are functional at the time of this study. the treatment plant capacity is 19, 000 m3 to 23,000m3 per day. however, daily demand is 43,000m3 per day for domestic uses (awssse, 2015). figure 1 study area map (courtesy adama drinking water agency) 2.3. water sampling and public health data collection who (2004) and apha (2013) guidelines have been adopted for sampling and analysis of water samples in the study area (apha, 2013). water samples were collected separately for microbial quality examination to reduce sample contamination in collection, preservation and testing. however, sample for the evaluation were taken separately which was evaluated in physico-chemical evaluation quality drinking water in the area. the drinking water quality in the study area correlated with public health. secondary and semi-processed data from health offices and primary data from all government treatment centres were utilized for public health assessment. an effort was made to identify access to safe drinking water, the top ten causes of morbidity, mortality and public health using as indicators for water quality. sampling methods based on stratified simple random sampling methods were considered. accordingly, seven strata were identified from sources-to-end point which is starting from raw water intake point to the community storage as shown below. the7 strata (s1 – s7) include;  s1-water sample from raw water intake point before pre-chlorination and coagulant aid point here, water samples are untreated raw water. therefore, expected water quality is low and this point will help to see the treatment level by comparing the treatment plant efficiency and how it will be delivered to the reservoirs.  s2water sample at treatment outlet point with a maximum residence time of 30 min after final treatment and before reaching the reservoir here sample collected is treated and expected that treatment have contribution to comply with drinking water standard. similarly, this sampling point will help to evaluate level of treatment and alteration with the next sampling point.  s3 water sample from the reservoirs: this sampling point is where water resides relatively for longer time. at which the water stay, material used to reserve water and volume of water at a time is different from other stratum.  s4 water sample from common community base point: this is common point to harvest water by lowincome community at any 500m radius distances. here human contact is high and relatively unprotected. so source of contamination will be expected that different and helps to compare with other stratums.  s5 water sample from the distribution system before reaching the community. this point of sample is undergrounded, almost least contact with human and relatively protected. this will help to compare and identify point of alteration.  s6 water sample user point at the end of distribution system and before storage at home: the point is where most of community harvest municipally provided water for both immediate consumption and later uses. this point will help that alteration of water is before collection or after collection, which means that, will help to identify supply system efficiency and hygienic level of water storage.  s7 water sample from community storage after 24hrs up to a maximum of 72 hrs storage time at home. keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 5 at this point water will stay longer time than other stratum and expected sources of water contamination is more and residual chlorine will be expected low. the sample collection and determination of minimum number of the sample per-month made based on who guideline and standards. accordingly, total 312 samples have been sampled from all the 7 strata (52 samples/month). the water samples were collected in the first week of each specified month during 8:00 am to 11:00 am. autoclaved 500ml glass bottle sampler was used, refrigerated (but not iced) and delivered to the oromia public health research, capacity building and quality assurance laboratory at adama (ophr lab) within an hour of collection. all safety precautions have been exercised during sampling, transport and analysis of the samples. all the water samples were analysed for total coliform bacteria (tcb), faecal coliform bacteria (fcb) and e. coli coliform bacteria in ophr laboratories, at adama. multiple-tube fermentation techniques are the most preferred techniques for detecting the selected group of coliform organisms in microbial analysis of water (apha, 2013) and the same has been adopted in the present work. since the water under consideration is from relatively good source, 5 tubes each with 10ml of double strength macconkey broth and 50ml double strength macconkey broth were used respectively (apha, 2013). since all the water samples except raw water point are chlorinated, 0.1ml of 1.8% of sodium thiosulfate was added to 100ml of water. water samples collected were placed aseptically into macconkey agar broth tubes for total coliforms, faecal coliforms and e. coli following the standard protocols as described by (apha, 2013; cheesbrough, 2006). incubation was carried out at 37°c for 24hrs for total coliforms and 44.5°c for 24hrs for faecal coliforms and count was carried out following the standard microbiological procedures by (apha, 2013). at every sampling point, samples have been taken to evaluate free residual chlorine. evaluation of free residual chlorine and sampling methods has been conducted as per the standard meted in apha (2013). 2.4. public health data sources and collection all the patients admitted with laboratory tests in either of eight government healthcare centres were considered for assessing the public health data in the study area. secondary and semi-processed data were taken from health offices and primary data were collected daily from government treatment centres during june-december 2016 by registering all admitted cases. only the top 20 diseases in the study area were considered in the assessment of public health data and existence of diseases such as dd in the top ten were considered as an indicators of impacts of water quality. the patients positively tested for waterborne and water related diseases such as typhoid fever, diarrhea, dysentery, pneumonia, acute upper respiratory infections, other unspecified diseases of the digestive and respiratory system used as indicators of water quality. additionally, diseases caused either directly or indirectly due to consumption of unsafe water and hygienic problem such as trachoma and other infected people are used as indicators of water quality impacts on public health in the specified period. health data relating to top 10 diseases causing morbidity and mortality in the area for the last five years was reviewed in relation to waterborne and water related diseases considered as a complement to the data collected from the treatment centres. additionally, the water quality and public health in that specific area was confirmed with the physical address of patients and medical records. 3. results and discussion 3.1. bacteriological quality of drinking water the microbial test of water samples were done in the ophr laboratory at adama town. the record of examination of collected water sample revealed that, 30.13% is positive for total coliform bacteria, 13.14% for faecal coliform bacteria and 3.21% for e.coli coliform bacteria. this result is the relative ratio of positive test result including the raw water. with exception of raw water starting from the treatment plant up to community storage, 26.28% of sample examined is positive for total coliform bacteria, 9.29% for faecal coliform bacteria and 0.96% for e.coli coliform bacteria is recorded. among which 67% of householder (at least one of the family) were hospitalized from where water sample were positive for e.coli. this is confirmed with the water sample and hospital records of the users. while 79.89% of those positive sample for either of indicator organism confirmed with the patients’ address and hospital records as well. e.coli exists in two stratum keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 6 among the seven strata. it was raw water intake (sa), accounting about 70% of e.coli which can be addressed through treatment. however, 30% was re-contamination due to improper handling at household. sb shows negative for all indicator organisms throughout the study, implying that the treatment plant at this point is complying with national and who standards for drinking water as far as microbial quality is concerned. this means that the contamination observed in the water distribution system is probably after water left the first couple of reservoirs. in case of samples taken from reservoirs (sr), 25% of the samples were positive for tcb specifically sr5 (tv oromia), sr6 (dhaka-adii) and sr7 (abba-geda) were positive for tcb, while 5.5% was contaminated with fcb specifically sr7. the analytical data of water samples from the distribution system before reaching the community (di) reveal that 18.33% was contaminated by tcb. water samples drawn from the centre of the town (kebele-09, 10, 12, 13 and 15) were contaminated. this is resulted due to aging of the system and leakages. the other positive samples in the distribution are from the newly expanded area in which illegal extension is a major problem in the study area, namely kebele-01, duket, daka-adi and tikurabay areas. similarly, 6.66% of the water samples from distribution, specifically from the centre are positive for fcb indicates that water has been contaminated with the faecal material of humans or other animal origin. as far as water quality in community storage is concern, 47.4% by tcb, 17.9% by fcb and 3.85% contaminated by e.coli while 25% and 8.3% of water sample examined from common communal point were contaminated with tcb and fcb but not e.coli. details of collected sample, number of positive sample and its percentage are shown in table 1. table 1: sample distribution ratio and summary of examined sample for bacteriological quality of drinking water (2016) s.n0 stratum descriptions total coliform faecal coliform e.coli positive sample % positive sample % positive sample % 1 s1 water sample from raw water intake point at different distance before prechlorination and coagulant aid point 12 100 12 100 7 58.33 2 s2 water sample no longer stayed for more than 30 minute after final treatment and before reaching reservoir (b) 0 0.0 0 0.0 0 0.00 3 s3 water sample from reservoir each separately (r), 9 25.0 2 5.6 0 0.00 4 s4 water sample from distribution system before reaching community (di) 11 18.3 4 6.7 0 0.00 5 s5 water sample from user point at the end of distribution system and before storage (ds) 16 20.5 6 7.7 0 0.00 6 s6 water sample taken from community storage after 24hrs up to maximum of 72hrs storage time (ei) 37 47.4 14 17.9 3 3.85 7 s7 water sample from common community base point (c or es), 9 25.0 3 8.3 0 0.00 total 94 41 10 percentage of positive result including raw water 30.13 13.14 3.21 percentage of positive result excluding raw water 26.28 9.29 0.96 keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 7 3.2. public health, waterborne and water related diseases in the area among 43,192 patients admitted in governmental health treatment centre with laboratory test during julydecember/2016 in the study area, 11,688 patient cases were mostly waterborne and water related problem. among this, 89.89 percent of patients were confirmed that they are from the area in which water sample result were positive for the indicator organism while the rest were patients using private water sources. about 43,192 gone for laboratory test during the specified period of the study treated in adama treatment services centre out of 342,974 people (total coverage). among those patients, 11688 cases were expected waterborne and/or water related health problem. in other words 13% of the total population of the study area were treated in either of the treatment centre. among those treated in either of treatment centre, 27.061% of treated people which is 3% of the total population were affected by waterborne or water related diseases. according to the report, diseases such as typhoid fever, diarrhea, dysentery, pneumonia, acute upper respiratory infections, unspecified diseases of the digestive and respiratory system and trachoma are leading top 20 diseases in the study area. within the spine of four months, 2717 patients were positive for diarrhea. 3.3. top ten mortality and morbidity causes pneumonia, typhoid fever, diarrhea and other waterborne and water related diseases are among most prone top ten diseases in the study area for the year of 2014-2016. the details of top ten morbidity and mortality with affected people and ratio have been given in the table 2-to-5. according to the result in table-2, there is no diseases which can have direct relation with water quality in the area rather there are some which can be expected to have correlation with sanitation practices in the affected society. for instance, severe acute malnutrition in the third ranked causes of mortality in the area, which covers 9.29% of mortality causes in the area, may be due to poor sanitation. because, severe acute malnutrition is indirectly cause due to water quality, which introduced due to improper sanitation. swollen limbs, feet and face characterize severe acute malnutrition. severe acute malnutrition, which is affecting about 2/3 of children in asia and 1/3 of african children and one of the major cause of death particularly in developing countries (bulti et al., 2017). according to the report, 16 million deaths due to severe acute malnutrition are resulted due to malnutrition itself directly and indirectly due to diarrhoea, pneumonia and poor hygiene (bulti et al., 2017). therefore, the existence of severe acute malnutrition in the third ranked causes of mortality in the area, which covers 9.29% of mortality causes in the area, may be due to poor sanitation. similarly, number of studies revealed that pneumonia is indirectly related to uses of unsafe water and improper sanitation (el nopy, 2017; stöppler, n.d.) and it is among the result in table-2 and 3, which is causing 4 to 7.10 percent of mortality in the area. 3.4. mortality and morbidity vs water quality the data from the health office of the town reveal that pneumonia, typhoid fever, diarrhea and other waterborne and water related diseases are among the top ten diseases during the years’ (2014-16). the data included in tables 3 to 6 illustrate the affected people and ratios with top ten diseases causing morbidity and mortality in the study area. among top ten causes of morbidity in the area, diarrhea, typhoid fever, pneumonia, acute upper respiratory infection and other or unspecified diseases are expected due to unsafe drinking water and sanitation related issue. similarly, diarrhea, typhoid fever, pneumonia, acute upper respiratory infection and other or unspecified diseases affecting public health in the area. the details are available in table 5 and 6 in which the causes of top 20 diseases admitted in the government hospital. in general, these diseases expected that indirectly caused due to unsafe drinking water and low sanitation. keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 8 table 2: top 20 diseases identified by laboratory test within 6 months top 20 diseases identified by laboratory test rank types of diseases admitted no.: patients 1 trauma (injury, fracture etc.) 3708 2 acute upper respiratory infections 3613 3 factors influencing health status and contact with health services, including visit for examination and investigation (check-up, examination for driving license etc.) 3437 4 diarrhoea 2718 5 other or unspecified diseases 2686 6 acute febrile illness (afi) 2571 7 urinary tract infection 1670 8 dyspepsia 1603 9 other or unspecified diseases of the skin and subcutaneous tissue 1531 10 pneumonia 1278 11 dental and gum diseases 1276 12 infections of the skin and subcutaneous tissue 1231 13 other or unspecified diseases of the eye and adnexa 1204 14 other or unspecified diseases of the respiratory system 1165 15 other or unspecified obstetric conditions 857 16 helminthiasis 792 17 causes of abnormal pregnancy, childbirth and puerperium 781 18 other or unspecified diseases of the digestive system 676 19 other or unspecified infectious and parasitic diseases 624 20 other or unspecified disorders of the genitourinary system 579 table 3: top ten mortality causes in adama special zone (2014-2016) in 2014-15 in 2015-16 rank diseases type number of patients % rank diseases type number of patients %e 1 human immunodeficiency virus (hiv) 53 28.96 1 human immunodeficiency virus (hiv) 59 29.5 2 neonatal sepsis 32 17.49 2 neonatal sepsis 33 16.5 3 severe acute malnutrition 17 9.29 3 birth asphyxia 26 13 4 cerebrovascular accident (stroke) 15 8.2 4 cirrhosis 17 8.5 5 pneumonia 13 7.1 5 severe acute malnutrition 15 7.5 6 cirrhosis of liver 12 6.56 6 cerebrovascular accident (stroke) 13 6.5 7 ischemic heart diseases 12 6.56 7 prematurity 11 5.5 8 all forms of tuberculosis 12 6.56 8 trauma (injury, fracture etc) 10 5 9 prematurity 9 4.92 9 meningitis 8 4 10 others delivery 8 4.37 10 pneumonia 8 4 total 183 100 total 200 100 keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 9 table 4: top ten morbidity causes in adama special zone in 2014-15 in 2015-16 rank diseases type number of patients % rank diseases type number of patients % 1 acute upper respiratory infection 23049 15.3 1 other or unspecified diseases of the eye and adnexa 28150 16.28 2 other or unspecified diseases of the eye and adnexa 20538 13.63 2 acute upper respiratory infection 25325 14.64 3 acute febrile illness (afi) 20496 13.6 3 acute febrile illness (afi) 21691 12.54 4 dyspepsia 16055 10.66 4 diarrhoea (non-bloody) 18626 10.77 5 urinary tract infection 15970 10.6 5 dyspepsia 18170 10.51 6 diarrhoea (non-bloody) 15583 10.34 6 trauma (injury, fracture, etc.,) 17439 10.08 7 trauma (injury, fracture, etc.) 14131 9.38 7 urinary tract infection 17195 9.94 8 other or unspecified diseases of the respiratory system 9465 6.28 8 pneumonia 9564 5.53 9 typhoid fever 7900 5.24 9 helminthiasis 8652 5 10 infection of the skin and subcutaneous tissue 7471 4.96 10 infection of the skin and subcutaneous tissue 8134 4.7 total 150658 100 total 172946 100 table 5: list of top 20 diseases in adama for the last five-year (2011-2016) (sources: adama health office, 2016) rank list of top 20 diseases admitted in government treatment centre in adama year of treatment in government health care centres (2011-2009 e.c) yearly average 2011 2012 2013 2014 2015 2016 total 1 acute upper respiratory infections 20398 20411 21613 21613 25271 5267 114573 19096 2 other or unspecified diseases of the eye and adnexa 16468 15290 16879 16879 28147 3159 96822 16137 3 acute febrile illness (afi) 17004 14561 14441 14441 21691 5275 87413 14569 4 other or unspecified diseases 12564 12317 16480 16480 22361 6188 86390 14398 5 dyspepsia 12954 13129 15658 15658 18068 4611 80078 13346 6 urinary tract infection 13694 13795 14631 14631 17101 4343 78195 13033 7 diarrhoea (non-bloody) 14483 12412 11201 11201 18600 5014 72911 12152 8 trauma (injury, fracture etc.) 14868 14716 10617 10617 16557 4492 71867 11978 9 pneumonia 9498 8030 7833 7833 9187 2164 44545 7424 10 factors influencing health status and contact with health services, including visit for examination and investigation (check-up, examination for driving license etc.) 10380 7944 5125 5125 10176 2760 41510 6918 11 helminthiasis 7332 6315 6572 6572 8650 1929 37370 6228 12 dental and gum diseases 7012 5769 7042 7042 6279 1593 34737 5790 13 other or unspecified diseases of the respiratory system 7649 6119 5585 5585 7145 1759 33842 5640 14 diseases of the musculoskeletal system and connective tissue 5974 5018 6044 6044 7652 1981 32713 5452 15 infections of the skin and subcutaneous tissue 5242 5038 4933 4933 7973 2171 30290 5048 16 hypertension and related diseases 5719 5377 5442 5442 6085 1262 29327 4888 17 typhoid fever 5205 4337 4987 4987 6949 1346 27811 4635 18 acute bronchitis 4024 4157 4526 4526 6426 1339 24998 4166 19 other or unspecified diseases of the digestive system 4143 3226 4831 4831 6054 1445 24530 4088 20 other or unspecified infectious and parasitic diseases 5507 4767 3486 3486 4777 1098 23121 3854 g. total 200118 182728 187926 187926 255149 59196 1073043 178841 keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 10 table 6: top 20 diseases treated in government health treatment centers (july-december/2016) rank types of diseases admitted name of hospital or health centre in which case is treated (augustdecember/2016) total average adama hospital adama hc biftu hc bokku shanan hc dambala hc hawas hc geda hc anolee hc 1 trauma (injury, fracture etc.) 3335 122 56 28 37 19 111 3708 530 2 acute upper respiratory infections 948 1286 347 80 280 210 462 3613 516 3 factors influencing health status and contact with health services, including visit for examination and investigation (check-up, examination for driving license etc.) 0 2220 180 0 8 0 1029 0 3437 491 4 diarrheal (non-bloody) 1373 620 264 81 252 75 53 0 2718 388 5 other or unspecified diseases 2435 149 14 17 37 11 23 0 2686 384 6 acute febrile illness (afi) 1046 922 268 44 127 75 89 0 2571 367 7 urinary tract infection 1125 280 51 35 12 46 121 0 1670 239 8 dyspepsia 1099 263 57 21 38 3 122 0 1603 229 9 other or unspecified diseases of the skin and subcutaneous tissue 1314 85 98 0 4 13 17 0 1531 219 10 pneumonia 983 156 34 9 23 57 16 0 1278 183 11 dental and gum diseases 1194 23 11 3 10 5 30 0 1276 182 12 infections of the skin and subcutaneous tissue 686 177 73 66 78 51 100 0 1231 176 13 other or unspecified diseases of the eye and adnexa 1081 36 42 15 4 13 13 0 1204 172 14 other or unspecified diseases of the respiratory system 666 4 128 214 0 29 124 0 1165 166 15 other or unspecified obstetric conditions 469 132 0 140 21 32 63 0 857 122 16 helminthiasis 280 148 67 1 72 134 90 0 792 113 17 causes of abnormal pregnancy, childbirth and puerperium 781 0 0 0 0 0 0 0 781 112 18 other or unspecified diseases of the digestive system 484 34 31 6 0 30 91 0 676 97 19 other or unspecified infectious and parasitic diseases 280 51 74 45 0 11 163 0 624 89 20 other or unspecified disorders of the genitourinary system 502 42 30 0 0 5 0 0 579 83 g. total 20081 6750 1825 805 1003 819 2717 0 34000 reviewed literature in relation to common pathogenic organism in water system revealed that, in developing countries drinking water is the major sources of pathogenic organism in addition to improper sanitation and unsafe food sources. the report continues that, worldwide1.7 million deaths recorded every year due to poor water qualities, sanitation and unhygienic condition that is resulting diarrhoeal disease infection. among those deaths, nine out of ten are in developing region (ashbolt, 2004; ashbolt, 2015). the major pathogens for these deaths are including organism such as rotavirus, campylobacter jejuni, vibro cholerae, cryptosporidium parvum, shingella spp, aeromonas spp and escherichia coli are reported. similarly, clostridium difficile, salmonella enterica, pseudomonas aeruginosa, legionella pneumophila, bacillus subtilis, staphylococcus aureus and klebsiella pneumonia are repeatedly reported as major waterborne pathogens in the water system (andy, 2015; ashbolt, 2015; trusek-holownia & noworyta, 2014; handley, 2013; freije, 2005; ashbolt, 2004; website, n.d.). these pathogens can be controlled by disinfection process, keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 11 especially by chlorination in water treatment system, but their recontamination to the water system with those microorganisms is the main problem (cloete et al., 2015; ashbolt, 2004; website, n.d). therefore, above listed diseases in the area may be caused due to one of those organisms. as a result, we can say that low level of residual chlorine in the water supply and recontamination of water in the system are affecting public health in the area. therefore, forthcoming work concerned about developing silver nanoparticles for antibacterial activities as a future direction in order to control those pathogens. 4. conclusion and recommendation the results of the study indicate that the koka water treatment plant (kdwtp) at adama town is complying with both ethiopian national and who standards for drinking water with respect to bacteriological quality. treated water quality continues to satisfy both the standards until it reach the first couple of reservoirs. however, the quality deteriorates stepwise starting from reservoirs, which does not receive treated water directly from the treatment plant. in its course, the treated water pass through tvo reservoir (r-5), dhaka-adi reservoir (r-6) and abba-geda reservoir (r-7) before making way into the reservoirs. the drinking water quality in r1 and r2 (“lugo-reservoirs”) which receive water directly from the treatment plant is good as far as microbial quality is concerned. even the 3rd reservoir at gelawudios (02 kebele reservoirs), that receives water from reservoir 1 and 2 is safe. it satisfies both national and who standards. however, reservoirs 5th, 6th and 7th which are farthest from the treatment plant and receive water from the reservoir 3 are not satisfying either of the standards. the alteration of microbial quality may be due to the low initial and reducing concentration of residual chlorine with distance. the physico-chemical quality of drinking water in those reservoirs shows that the concentration of residual chlorine is below the standard and varies with time. this seems to be the main reason for recontamination and also the leakages in the distribution system may be the cause for aggravating the problem. the contamination of reservoir-7 on the other hand may be due to both ambience and maintenance problems. however, contamination of water in reservoir-6 may be due to bird droppings in and around, opening on the top of the reservoir and declining concentration of residual chlorine. in case of r-5, the leakage observed in the bottom of the metallic reservoirs maybe the main reason for the re-contamination in addition to low residual chlorine concentration. in general, aging of pipeline, especially in kebele 09, 10, 13, and 15 are also other expected reasons for the contamination of water in the distribution system. however, the contamination at the user end point and distribution in kebele-01 and tikur-abbay might be due to illegal extension from the main pipeline and breakage of pipelines due to urban expansion work in the area. generally, the study shows that 20.5% of water in the distribution system, 47.4% of water in the community storage and 25% of common community base points are contaminated with tcb. similarly, 7.7% of water in the distribution system, 17.9% of water in the community storage and 8.3% of common community base points are contaminated with fcb. however, the most pathogenic bacteriological quality indicator organism e.coli is only re-appearing in community storage. since waterborne diseases, such as diarrheal diseases and pneumonia continue to be top ten diseases in the area, the impact of water quality (either source or contaminant) adversely affecting public health. data taken from adama town health office for the last five years (2011-2015) and collected data from all government health treatment centres revealed that both morbidity and mortality are dominated by waterborne and water related diseases. those diseases include typhoid fever, diarrhoea, dyspepsia, pneumonia, dysentery, acute upper respiratory infections, and other or unspecified diseases of the digestive and respiratory system are among top ten diseases. public health in the study area has been affected by drinking water quality, mainly due to unhygienic handling. additionally, illegal extension from main pipeline, infrastructural expansion impacts on pipeline, initial concentration of residual chlorine, pipeline aging, intermittent water supply and low level of public awareness in general are the main causes of water quality alteration. water distribution by rotation is also seen as one of main reasons for the contamination. the distribution system will stay for 1-6 days without water promoting water contamination due to lower pressure in the pipeline. apart from this, the water is stored for 1-6 days at individual storage points keredin temam et al. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 12 encouraging water contamination with poor awareness of the community in water handling. therefore, the discontinuities of supply due to supply and demand gap is also contributing towards diminishing water quality and imposing impact on public health. in accordance with the findings of the study and reviewed literature the following recommendations were forwarded:  the initial concentration of chlorination process has to be revised considering the distance between the treatment plant and reservoirs.  improvement of the ambience of all the reservoirs is recommended to 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(n.d.). retrieved december 1, 2018, from types of waterborne pathogens found in your water system, htp://www.blueearthlabs.com/maintenance-cleaning/types-of-waterborne-pathogens-found-in-your-water-system/ who/unicef joint water supply and sanitation monitoring programme, & world health organization. (2014). progress on drinking water and sanitation: 2014 update. world health organization. world health organization. (2013). progress on sanitation and drinking-water. world health organization. 124 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 comparison studies of bio-diesel production from seed oils through a sustainable catalyst k.s.k. rao patnaik1, melakuu tesfaye alemea1, m. usha rani2, y. rajeshwer rao3 1 adama science and technology university, school of mechanical, chemical and materials engineering, dept. of chemical engineering, p.o.box.1888, adama, ethiopia e.mail:drkskrao@gmail.com 2 dept.of chemical engineering, osmania university, hyderabad, india 3 department of chemistry, rajiv gandhi university of knowledge technologies, iiit basara-504 107, telangana state, india abstract increase in demand for energy production and its supply, rise in petroleum prices, environmental issues have lead in search of new alternative energy resources. this eventually lead in using edible oils as essential feed stock but in recent years, the food verses fuel controversy made edible oil a non-ideal feed stock. in search for alternative non-edible feed stocks, guizotiaabyssinica and cucumissativus seed oils were found to be potential feed stocks for the synthesis of bio-diesel through transesterification process using crystalline manganese carbonate as catalyst. crystalline manganese carbonate was found to be a sustainable catalyst since higher yields were obtained at 1 wt% catalyst for both the oils. the catalyst is pure, crystalline and ash colored in nature. it is a heterogeneous catalyst and promotes reuse of the catalyst for all most seven successive runs. it is a low cost and easily available, non-corrosive, versatile, environmental friendly, green and sustainable catalyst for the transesterification of non-edible feed stocks. in the present study, a comparison on effects of parameters like methanol quantity, catalyst amount, reaction time and reaction temperature for guizotiaabyssinica and cucumissativus seed and edible oils are done. the results show that using the catalyst crystallinemanganese carbonate gives higher yields and conversions. the catalyst is neither corrosive nor emulsion forming and is easier to separate. the research focuses on sustainable catalyst and feed stocks that are economic and environmental friendly keywords: guizotiaabyssinica, cucumissativus, edibleoils, manganese carbonate, transesterification, bio-diesel 1. introduction as petroleum reserves are decreasing and demand for energy production is increasing, bio-diesel is becoming a promising alternative patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 125 © adama science & technology university https://ejssd.astu.edu.et fuel resource. various attempts are being made on the new feed stocks and catalysts, for the production of bio-diesel [1-5]. bio-diesel synthesis uses solid catalysts which have cheaper production cost and can be reused [6]. biodiesel is chiefly produced by transesterification process where triglycerides of oils in the presence of alcohol and catalyst yield biodiesel. in usa and europe, soybean and rapeseed are common feedstock for bio-diesel production whereas palm is the feedstock in south asia [7-10]. the above mentioned soybean, rapeseed and palm are the edible oil feedstocks and use of these edible oils for the production of bio-diesel may lead to inflationary pressures in vegetable oil market [11-14]. therefore, attempts are being made in discovering nonedible feedstocks for the production of bio-diesel. in the present work, guizotiaab yssinica and cucumissativus seed and various edible oils are taken and compared for bio-diesel yields. 2. materials and methods 2.1. materials: guizotia abyssinica seeds are collected from araku, vizag, andhra pradesh, orissa and karnataka, india cucumissativus seed oil, crystalline manganese carbonate and methanol are purchased directly from the laboratories. analysis of guizotia abyssinica and cucumissativus oils: guizotia abyssinica and cucumis sativa seed oil (cucumber oil) are subjected to gas chromatography to determine the composition. the samples are analyzed for their fatty acid content. table1 and table2 give the fatty acid composition of the two oils. patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 126 © adama science & technology university https://ejssd.astu.edu.et table1: fatty acid composition of guizotia abyssinica oil fatty acids percentage (%) composition palmitic (c16/0) 9.2 stearic (c18/0) 10.1 oleic (c18/1) 9.0 linoleic (c18/2) 71.7 reuse and recovery of catalyst: in the present work, the manganese carbonate catalyst is recovered by filtration and washed with 80°c distilled water 4-5 times. then the catalyst is dried at 50°c for 35 hours in the hot air oven. after the complete drying the catalyst is used in the transestrification reaction. the efficiency of the catalyst is 95%. the catalyst is still efficient even after seven successive runs. experimental procedure: the materials are taken in the reaction flask and heated to a desired temperature. the mixture of catalyst in methanol with different concentrations is used for the conversion of cucumis sativa seed oil and guizotiaabyssinica seed oil to fame. transesterification reactions are performed in a 150 ml round bottom flask with a reflux condenser, stirring is provided by a magnetic stirrer. the stirrer is set at a constant speed throughout the experiments. the methanol and catalyst mixture are added to the round bottom flask containing oil. at that point, the reactions are kept under reflux conditions. the formation of methyl esters from the oils are monitored by thin layer chromatography. the methyl esters are washed with distilled water and concentrated under vacuum to afford fame. 3. results and discussion effect of methanol to oil ratio: methanol to oil ratio is one of the most important variables in methyl ester production. fig.1 shows, 1:1 methanol to oil ratio patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 127 © adama science & technology university https://ejssd.astu.edu.et gives highest biodiesel yield for cucumis sativus seed oil whereas 5:1 methanol to oil ratio gives highest biodiesel yield for guizotia abyssinica seed oil. table2: fatty acid composition of cucumissativus oil: figure.1: effect of methanol to oil ratio effect of catalyst quantity: fig.2 shows at 1 wt% catalyst is observed with higher yields. it is obtained 95% of biodiesel yield from guizotiaabyssinica seed oil and 86% of biodiesel yield from cucumis sativa seed oil. figure.2: effect of catalyst quantity effect of reaction temperature: as temperature increases, from fig.3 it is observed that biodiesel yield increases. beyond 700c emulsification takes place which is not desirable. effect of reaction time: during the transesterification reaction, continuous stirring is provided at a constant rate. in fig.4, the conversion of guizotiaabyssinica seed oil to biodiesel yield of 95% was achieved in 180 min whereas for fatty acids cucumber oil % palmitic(c16/0) 11 stearic(c18/0) 7 oleic(c18/1) 14 linoleic(c18/2) 68 patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 128 © adama science & technology university https://ejssd.astu.edu.et cucumissativus seed oil it took 180 min to achieve 86% yield. figure.3: effect of reaction temperature figure.4: effect of reaction time comparison with other edible oils: figures.5 compared with different vegetable oils with the present study. it is concluded that vegetable oils primarily contain trigycerides and their chemical structure is significantly different from that of mineral diesel. transterification is an efficient method to convert high viscosity vegetable oils into a fuel with patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 129 © adama science & technology university https://ejssd.astu.edu.et chemical properties similar to those of mineral diesel. consequently, vegetable oil causes poor fuel atomization, incomplete combustion and carbon deposition on the injector and valve seats, resulting in serious engine fouling. [15] different approaches have been considered to reduce the high viscosity of vegetable oils. biodiesel properties are strongly influenced by the properties of the individual fatty esters. [8] in searching for alternative method with non-edible seed oils, guizotia abyssinica and cucumissativus with nanosized mn (ii) carbonate could be used as an efficient and selective catalyst. the authors concluded that guizotia abyssinica and cucumissativus non-edible seed oils are better than edible oils and also to avoid the controversy of food and fuel. figure.5: effect of methanol to oil ratio, reaction time, amount of catalyst and reaction temperature on yield of biodiesel patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 130 © adama science & technology university https://ejssd.astu.edu.et 4. conclusion  the above graphs show that at 1:1 ratio of methanol to oil at 650c, catalyst weight of 1% gives the highest yield of 86% for cucumissativus seed oil.  at 5:1 ratio of methanol to oil at 650c, catalyst weight of 1% gives the highest yield of 95% for guizoabyssinica seed oil.  it is observed that highest yields are obtained at 1 wt% catalyst for both the oils and the catalyst can be reused. therefore, it can be concluded that crystalline manganese carbonate as a sustainable, green catalyst.  the authors concluded that guizotia abyssinica and cucumissativus non-edible seed oils are better than edible oils and also to avoid the controversy of food and fuel. acknowledgement: the authors would like to thank the principal, university college of technology, osmania university, hyderabad, india for providing research facilities. the authors also want to acknowledge the president, adama science and technology university and dean, somcme, department of chemical engineering, adama, ethiopia for providing computer facilities. references: [1] rakesh sarin, meeta sharma, arif ali khan, “studies on guizotiabyssinica l. oil: biodiesel synthesis and process optimization”, bioresource technology, 100, 2009, pp. 41874192. [2] yerraguntla rajeshwer rao, pudukulathan kader zubaidha, jakku narender reddy, dasharath dattatraya kondhare, deshmukh shivagi sushma, “crystalline manganese carbonate a green catalyst for biodiesel production”, green and sustainable patnaik et al. ethiop. j. sci. sustain. dev., 5 (1), 2018 131 © adama science & technology university https://ejssd.astu.edu.et chemistry, 2, 2012, pp.1420. [3] rajeshwer y. rao, pudukulathan k. zubaidha, dasharath d. kondhare, narender j. reddy, sushma s. deshmukh, “biodiesel production from argemone mexicana seed oil using crystalline manganese carbonate”, polish journal of chemical technology, 14, 1, 2012, pp. 65-70. 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[15] m. s. graboski and r. l. mccormick, prog. energy combust. sci. 24, 125 (1998). 1 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper characterization of home-made and industrially produced niger seed oils by fluorescence spectroscopy alemu kebede , minda regasa department of applied physics, school of applied natural science, adama science and technology university, p.o. box: 1888, adama, ethiopia article info abstract article history: received 06 june 2022 received in revised form 16 september 2022 accepted 21 september 2022 home-made and industrially produced niger seed oils were characterized by a fluorescence spectrometer to analyze the impact of the industrial process on the physical and chemical properties of the oil. the excitation wavelength was varied from 350 nm–380 nm with an incremental step of 10 nm, and the slit width was kept at 5 nm. experimental results indicated that the major components in oil samples (home-made, unrefined, and refined industrially produced) were vitamin e, poly-unsaturated fatty acid, and chlorophyll. emission spectra recorded in the range of band between 400 nm – 500 nm were related to poly-unsaturated fatty acids; those spectra recorded in the range of band between 500 nm-550 nm with a peak around 548 nm belong to vitamins e; and the band of emission wavelength between 650 nm – 725 nm were due to chlorophyll. it was also observed that the refined oil had a very small vitamin e peak. this could be associated with the heating process of refining, as vitamin e is heatunstable. moreover, the emergence of new peaks in the spectra of the refined oil between 400 nm – 450 nm was due to fat-soluble vitamins and lipids that emerge as a result of oxidative reaction during the heating process. moreover, an increase in excitation wavelength also resulted in a blue shift of the emission spectra. this was because of the presence of more than one fluorophore (luminophore) in the molecule. the calculated quantum yield of the fluorescence of the sample/un-purified was 0.01042, which is a 10% reduction compared to the purified oil. an increase in ph values also resulted in a decrease in fluorescence intensity and vice-versa. keywords: niger seed, fluorescence spectroscopy, quantum yield, antioxidant, 1. introduction vegetable oils are the main source of fatty acids, which are predominantly triglycerides (95% 98%); the remaining (2% -5%) consists of complex mixtures of minor compounds in a wide range of chemical classes (romaniuk et al., 2004). the proportion of saturated and unsaturated fatty acids has an important role in the behaviors of vegetable oils. the degradation of vegetable oil quality is essentially caused by unsaturated fatty acid oxidation, which is a complex phenomenon that generates mainly hydroperoxides but also volatile corresponding author, e-mail: nuuftoleeta@gmail.com https://doi.org/10.20372/ejssdastu:v10.i1.2023.509 compounds through a three-phase process of initiation, propagation and termination (laguerre et al., 2007). niger seed (guizotia abyssinica) is one of the most important edible oil crops in ethiopia, providing 50% to 60% of the indigenous edible oils (dutta et al., 1994). the use of niger seeds as a source of edible oil through home-level manufacturing has been practiced since ancient times. the lightly roasted seed is first pounded by adding hot water and then transferring the pounded http://www.ejssd.astu.edu/ mailto:nuuftoleeta@gmail.com alemu kebede and minda regasa ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 2 mash into an earthen pot which is rotated to let the oil migrate to the top and separated by decanting the oil. oxidized lipids not only result in objectionable flavors and odors, loss of colour and nutrient value but also generate potentially toxic compounds which may be detrimental to the health of consumers (luzia et al., 1997). one of the most effective ways of retarding lipid oxidation and hence increasing the shelf life of oils and oil products is to incorporate antioxidants which may be defined as substances that when present at low concentration compared with those of oxidizable substrates significantly delay or prevent the oxidation of that substrate. in doing so, antioxidants slow down the rate at which oxidation occurs. the application of natural antioxidants as food additives was also raised because of their potential health benefits. it was reported that natural antioxidants decrease the risks of heart disease more than their counter-synthetic antioxidants (shaker, 2007). the addition of antioxidants and bleaching to reduce oxidation and loss of colour and taste requires a great deal of knowledge of food chemistry and the usage of sophisticated equipment (guimet et al., 2004). in addition, a controlled environment and state-of-the-art laboratory are essential. most of the methods are based on the extraction of neutral lipids with hexane or petroleum ether, and the extracted components are estimated gravimetrically. the method requires a triplicate grinding/extraction, making it lengthy and very detailed for the analyst (barthet and daun, 2004). in this study, the researcher was interested in the photo-physical analysis of oil samples to investigate the impact of the industrial process on the antioxidant property, its quantum yield, and nutrient contents of oil using a recently developed food characterization technique, which uses the fluorescence property of a sample under investigation. the method is fast, cheap, non-destructive, does not use chemicals, is environmentally friendly, and can be used at all levels of manufacturing. it could also be used as a quality control technique in such a way that the abundance and presence of essential elements could be controlled or monitored online while the process of manufacturing is going on. hazardous pollutants in the manufacturing process, if any, could also be identified. thus, this method is so vital for the industrialists, the wider community, and the scientific community. 2. materials and methods mature, normal and dried niger seeds produced at the household level were bought from the local market. the seeds were washed and roasted before undergoing the process; then. they were pounded in a wooden mortar by a pestle. refined and unrefined niger seed oils were purchased from the local oil manufacturer in adama city. the fluorescence spectra of all niger seed oil samples were characterized by using a fluorescence spectrometer (cary eclipse-my18490002) with the spectral range of detection ranging from 200 nm up to 900 nm. a continuous xenon arc lamp and photomultiplier were used as excitation sources and detectors, respectively. boiling water was added slightly and then pounded niger seed oil into an earthen pot which was manually rotated to move the oil to the top, and the oil was separated by decantation. the decanted oil was further filtered by a sieve to avoid solid suspensions. the purified samples were stored in a glass bottle and kept at room temperature for experimentation. after different molar concentrations were prepared, emission spectra were collected in the visible region of the spectrum. the excitation wavelength ranged from 350 nm to 380 nm with an increment of 10 nm. the widths of the slits were fixed at 10 nm for excitation and 5 nm for emission monochromators. to ensure the validity of the different measurements, four scans were made at each excitation wavelength. data analysis was done using origin-pro 8 software. 3. results and discussion 3.1. analysis of home-made niger seed oils for excitation wavelength ranging from 350 nm to 380 nm, with an incremental step of 10 nm, the emission spectra were observed to show fluorescence peaks in the range λem: 400 nm – 725 nm. different peaks and bands of fluorescence were observed for each excitation wavelength as illustrated in figure 1. to differentiate the spectra, blue, red and black colours were assigned to each excitation wavelength and their corresponding emission spectra: green colour for spectra excited at λex: 380 nm, blue colour for spectra excited at λex: 370 nm, red colour for spectra excited at λex: 360 nm, and black colour for spectra excited at λex: 350 nm, respectively. alemu kebede and minda regasa ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 3 figure 1: fluorescence intensity versus wavelength of homemade niger seed oil comparing the result with literature values for vegetable oils and chlorophyll fluorescence (yvon et al., 2011 and theppawut et al., 2015), it was concluded that emission spectra recorded in the range of band between 400 nm 500nm are related to polyunsaturated fatty acids. on the other hand, emission spectra recorded in the range of band between 500nm-550nm with a peak around 548nm was related to vitamin e, and the regions of emission wavelength band between 650nm 725nm was due to chlorophyll present in the niger seed oil. the resulting fluorescence spectra are indicated in figure 1. it was observed that as the wavelength of excitation increased from 350nm to 380nm, the emission spectra underwent a blue shift towards a shorter wavelength and resulted in higher intensity counts. this could be due to the presence of more than one fluorophore (luminophore) in the molecule or a high concentration of polyunsaturated fatty acid. the emission peaks for vitamin e also had a higher proportion than chlorophyll. 3.2 analysis of unrefined niger seed oils the excitation wavelength used was similar to part 3.1. the corresponding emission spectra were observed to show fluorescence peaks in the range λem: 400 nm – 725 nm. different peaks and bands of fluorescence were observed for each excitation wavelength. to differentiate the different spectra, blue, red and black colours were assigned to each excitation wavelength and their corresponding spectra: green colour for spectra excited at λex: 380 nm, blue colour for spectra excited at λex: 370 nm, red colour for spectra excited at λex: 360 nm, and black color for spectra excited at λex: 350 nm, respectively (figure 2). the values for fluorescence spectra in the range of bands between 400 nm – 500 nm were due to unsaturated fat and fatsoluble vitamins (yvon et al., 2011). it was observed that the fluorescence intensity increased by increasing exciting wavelengths from 350nm-380nm and there was also a blue shift in the emission wavelength. the peak of fluorescence for vitamin e around the band 548 nm was found to be smaller compared to the homemade oil. this was expected to be the result of oxidation during the factory process. the bands around 676 nm belong to chlorophyll fluorescence (theppawut et al., 2015). 3.3 analysis of refined niger seed oils a similar procedure was followed in parts 3.1 and 3.2 to characterize the refined niger seed oil. the excitation wavelength range and fluorescence bands of the spectral region were observed to be in the same range. however, high intensity and many new bands of peaks emerged between 400 nm – 500 nm as shown in figure 3. this could result from high-temperature oxidation that induced chemical transformation. the bands were assigned to fat‐ soluble vitamins, lipids, and hydroperoxides (yvon et al., 2011). on the other hand, the peak that existed around 548 nm, in home-made oil, figure 1, has almost disappeared. this indicated the absence of vitamin e. the bands at 676 nm have been assigned to chlorophyll as already cited above. the researcher concludes that bleaching used to make refined oils transparent and heating at very high temperatures to extract the maximum amount of oil from the seeds could result in the loss of nutrients like vitamin e, color and taste. alemu kebede and minda regasa ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 4 figure 2: fluorescence intensity versus wavelength of unrefined niger seed oil 3.4. difference & similarity between homemade, refined & unrefined niger seed oil the major difference between homemade, unrefined, and refined niger seed oils could be observed in figure 4 below. the process of refining oil undergoes so many chemical processes: heating the oil at a very high temperature, chemical bleaching to make it transparent, and loss of unpleasant odor. the oxidation during the heating process resulted in the emergence of new peaks and loss of essential nutrients like vitamin e. the unrefined oils retained many of the nutrients and antioxidants of the original seed. the only downside of unrefined oils was that it was often less stable than refined oils. they are more prone to going acidic in a shorter time. it was also observed that the relative intensities of the fat and fat-soluble vitamins for home made oil was lower. however, both industrially produced oil samples and unrefined and refined oil samples, show similar behaviour in fat and fat-soluble vitamins. since vitamin e is not heat-stable, prolonged time of heating and the high temperature seems to have resulted in negligible pear in both samples. thus, industrially manufactured oils lack antioxidant properties. homemade niger seed oil is an unrefined oil. it differed from the industrially produced oils in that it has a higher concentration of vitamin e. unrefined niger seed oil is nutritionally valuable, as it contains linoleic acid (unsaturated fats), which are essential for good health. they prevent cardiovascular diseases and are precursors of structural components of plasma membranes and some metabolic regulatory compounds. the low intensity of the peaks around 400nm 475 nm is due to their large content of monounsaturated fatty acids and phenolic antioxidants, like vitamin e, which provide more stability against oxidation. figure 3: fluorescence intensity versus wavelength of refined niger seed oil alemu kebede and minda regasa ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 5 figure 4. comparison of spectral peaks for home-made, unrefined and refined niger seed oils of different acidity (ph) figure 5. integrated fluorescence intensity versus absorbance (a.u). on the other hand, refined oil shows a high-intensity peak around 400 nm 475nm which is due to fatty acid oxidation formed as a result of the high-temperature heating. it was also observed that the ph values of the home-made, unrefined, and refined niger seed oil were 5.7, 5.4, and 5.1, respectively. so, the unrefined niger seed oil has high acidity. as fluorescence is ph sensitive, the small variations in ph values have resulted in spectral variation (figure 4). a decrease in ph increased to a fluorescence peak. 3.5. determination of fluorescence quantum yield (qy) fluorescence quantum yield (qy) for niger seed oils was determined from the gradients of the integrated fluorescence area versus absorbance (figure 5). relative fluorescence qy values were calculated employing standard equations from the literature (williams et al., 1983) where the relative indices of refraction of the samples were closer to unity. using the quantum yield of a reference sample (the refined oil), which was 0.102, the fluorescence quantum yield of a test sample was calculated and found to be 0.01042. the result indicated a 10% reduction in the quantum yield of the fluorescence property due to various quenching effects of impurities that existed in the unpurified oil sample. 4. conclusion the study has successfully distinguished the major fluorescent compounds found in the home-made and industrially produced niger seed oils. the variations of each compound (oxidation products, vitamin e, and chlorophyll) resulted from the process of heating and purification. the study proved the possibility of using alemu kebede and minda regasa ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 6 fluorescence spectroscopy for analysis of the photophysical properties to check the quality of vegetable oils. 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(2011). characterization of vegetable oils by fluorescence spectroscopy. food sci. nutr: 2(1) 692-699 1 © 2020 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (1), 2022 journal home page: www.ejssd.astu.edu.et astu research paper yield dynamics and nutrient quality of napier grass (pennisetum purpureum) varieties under consecutive harvests tessema tesfaye atumo, getachew gudero mengesha, milkias fanta heliso, getinet kebede kalsa southern agricultural research institute, arba minch agricultural research center, p.o.box 2228, arba minch, ethiopia article info abstract article history: received 10 june 2021 received in revised form 08 august 2021 accepted 09 september 2021 negative feed balance in terms of dry matter and forage quality has been affecting animal production in ethiopian livestock system. yield dynamics and forage quality assessment of ten napier grass (pennisetum purpureum schumach.) genotypes to assess the yield and nutritional quality of the grass was conducted in the field of chano mille research substation from september 2018 to november 2019. the experiment was laid out in randomized complete block design with three replications. all growth parameters showed significant (p<0.01) variation among genotypes that were contributing either to yield or quality. depending on the weather condition of growing months, dry matter yield was varied among genotypes and harvesting months significantly (p<0.01). dry matter yield varied from 4.87 to 17.35 t/ha for weather variation in growing months and from 9.57 to 18.4 t/ha for genotype variation. leaf to stem ratio was not varied significantly among genotypes. stem and leaf quality variation among genotypes for calcium, phosphorus and crude protein was significant while not for neutral and acid detergent fibers. zehone_02 and ilri_16835 genotypes could be of optimum dry matter yield and quality to be used as a feed option in a study area and similar agro-ecological zones. assessing silage and hay quality and animal preference warranted with the production of the crop under irrigated condition. keywords: calcium genotype phosphorus zehone_02 1. introduction napier grass (pennisetum purpureum schumach.) is a fast-growing perennial grass native to sub-saharan africa that is widely growing across the tropical and subtropical regions of the world (alemayehu teressa et al., 2017). its high production, ease of establishment and regeneration, persistence, and enhanced water use efficiency make napier grass the primary forage of choice in the regions of eastern and central africa, where smallholder dairy farmers and pastoralists suffer from intermittent droughts and possess limited irrigation infrastructure (nyambati et al., 2010). napier grass is recommended for smallholder crop-livestock farming systems especially in dairy and feedlot production systems (halim et al., 2013). corresponding author, e-mail: tessema4@gmail.com https://doi.org/10.20372/ejssdastu:v9.i1.2022.379 most smallholder livestock producers predominantly own small and fragmented pieces of land, therefore, napier grass offer a best-fit alternative to other feed options, as these are high yielding forages which require a minimum amount of inputs and land (alemayehu teressa et al., 2017). different cultivars of napier grass produced as higher dry matter yield as 60 tons per hectare per year (rengsirikul et al., 2013) whereas the yield may be more depending on the cultivar in use, the environment and management options. the tallest or normal napier grass varieties produce higher dry matter yield than the shortest or dwarf ones (williams and hanna, 1995) where in tropical and subtropical regions with annual moisture of 750 to 2500 mm in an altitude http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i1.2022.379 tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 2 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 jan feb mar apr may jun jul aug sep oct nov dec t e m p e ra tu re ( o c ) r a in fa ll ( m m ) rf2018 rf2019 rf (mm 2009-2019) tmx2018 tmx2019 max temp (2009-2019) tmn2018 tmn2019 tmn(2009-2019) ranging from sea level to 2100 meter above sea level (nyambati et al., 2010). therefore, the objective of this study was to evaluate the agronomic performance, yield dynamics and nutritive quality of ten varieties of napier grass in 15 months growing period and subsequently identify superior varieties based on those criteria. 2. materials and methods evaluation of yield dynamics and nutrient quality of ten napier grass varieties were conducted starting from september 2018 to november 2019 at the arba minch agricultural research center substation (6°03'43.7"n, 37°33'41.5"e; 1,220 meter above sea level) (figure 1). the mean annual rainfall of the location is 938.55 mm with average minimum and maximum temperatures of 17.3 and 30.3°c, respectively. weather data including mean monthly rainfall and maximum and minimum temperatures during the course of the trial are presented in figure 2. planting year 2018 (809.26 mm) was characterized with 13.8% below and production year 2019 (1171.6 mm) was characterized with 23.35% above the normal precipitation of 10 years average value (938.55 mm). the bimodal character of rainfall showed that january, february, march, july, august and december have the lowest precipitation while april, may, june, september, october and november characterized as better precipitation in the year with the figure 1: location map of the study area figure 2: rainfall (rf), maximum temperature (tmn) and minimum temperatures (tmx) tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 3 peak in april and may. no irrigation supplemented in the low moisture seasons for the trial. the soil is a sandy loam (sand 64%, clay 15%, silt 21%), with ph 6.2, available phosphorus 14.5 mg/kg, total nitrogen 0.29%, organic carbon 1.19%, organic matter 1.63% and potassium 1.12 cmolc/kg. the experimental soil is in the range of moderately acidic (ata, 2016), low available phosphorus, optimum amount of total nitrogen, low organic carbon and organic matter and high potassium concentration (landon, 1991). field experiment of nine napier grass accessions (ilri_14982, ilri_16782, ilri_16783, ilri_16784, ilri_16800, ilri_16817, ilri_16821, ilri_16835, and ilri_16837) with one standard check (zehone_02 released in 2017) (gezahegn kebede et al., 2019) was laid out in randomized complete block design with three replications. stem cuttings with three nodes were planted to 16 holes with a depth of 15-20 cm at 45° in 3 x 2 m2 plots (four rows per plot) with plant to plant spacing of 50 cm, between row 75 cm, which could have 26666 plants per hectare. the distance between plots and blocks were 100 cm and 200 cm, respectively. nitrogen, phosphorus, sulfur (19% n: 37% p2o5:7% s) 100 kg/ha blended fertilizer was applied at planting and no additional fertilizer was added after frequent harvesting. the plants in experimental plots were allowed to establish for a period of four months before the first data was taken in january 2019. there were a total of seven harvests over a period of 12 months starting the first data at january 2019 to the last at november 2019 with the harvesting interval of -/+7 weeks depending on the weather condition of the season and growth rate of the grass. growth measurements were undertaken for plant height (ph), leaf number per plant (lnpp), leaf length (ll), leaf width (lw), tiller number per plant (tnpp) and circumference (cf) before harvesting of the grass for fresh matter yield and dry matter yield in each harvest from randomly selected central net rows of the plot of five plants. ph was measured using tape meter from ground to base of top leaf. lnpp was counted for five plants from central rows and recorded to calculate the average number of leaves. from randomly selected five plants there were five central leaves marked to measure ll by using tape meter from attachment with the stem to leaf tip. lw was also measured in centimeter form five leaves using graduated caliper. the number of tillers was counted from five plants from each plot. the diameter circumference was measured by using tape meter from randomly selected five plant holes to calculate the average measurement for a plant culm diameter. grasses on the plot were cut close to the ground level (5 cm above ground) using manual sickle. the cut pieces were collected from five plants to make composite sample of 300 gram for leaf and stem independently to compute leaf to stem ratio (lsr). the plot green forage yield was measured by spring balance to figure fresh matter yield per hectare. the sample was taken to laboratory and exposed to oven at 65°c for 24 h to get constant dry weight and calculate dry matter yield (dmy (t/ha)). the dry matter yield was determined for seven harvests by using the formula: dm% = odw fw ∗ 100 where, dm% is dry matter percent, odw is oven dry weight, fw is fresh weight dmy (t ha⁄ ) = fmy(t ha⁄ ) ∗ dm% where, dmy is dry matter yield, and fmy is fresh matter yield the dried samples were then ground to pass 1 mm sieve tube and used for forage quality analysis. crude protein (cp), neutral detergent fiber (ndf), acid detergent fiber (adf), acid detergent lignin (adl), available phosphorus (p %dm) and calcium (ca %dm) for leaf and stem samples detected in separate way. cp, ndf, adf and adl were assessed in the laboratory according to the procedures of national forage testing associations (undersander, 2014). phosphorous and calcium content of the forage was determined by extraction with 0.5 m nahco3 (olsen et al., 1954). collected data were analyzed using the analysis of variance procedure and least significance difference (lsd0.05) of genstat statistical sofware version 18, vsn international ltd, uk (payne et al., 2015). 3. results and discussion 3.1.results mean square values for growth parameters such as ph in cm, lnpp, ll in cm, and lw, tnpp, cf and lsr; dmy in t/ha and forage nutritional quality for stem and leaf such as crude protein (scp%, lcp%), tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 4 acid detergent fiber (sadf%, ladf%), neutral detergent fiber (sndf%, lndf%), calcium concentration (sca, lca) and available phosphorus (savp, lavp) data was presented in table 1. growth and yield parameters were shown significant variation among genotypes and harvesting period through the growing period except for leaf to stem ratio. interaction effect of genotypes with harvesting period was significantly affected the dry matter yield and plant height in this study. growth parameters mean plant height was in a range between 63.91 and 85.72 cm (table 2). plant height was significantly (p<0.01) varied among genotypes and the highest height was recorded for genotype ilri_16821 (85.72 cm) followed by ilri_16835 (83.77 cm) in the test whereas the shortest one was ilri_16817 with the height of 63.91 cm. plant height contributes a lot to the dry matter production of forage crops. leaf number per plant mean varied significantly (p<0.05) among napier genotypes table 1: analysis of variances presenting 10 napier grass genotypes evaluation during 2018-2019 source of variation d.f. dmy (t/ha) ph (cm) lnpp tnpp lsr lw (cm) ll (cm) cf (cm) replication 2 116.9 514 8.75 315.2 0.34 1.05 76.13 921.6 genotype 9 197.7*** 457.* 2.08*** 1227.2*** 0.41 1.31*** 136.47* 1177.6* harvesting period 6 2002.4*** 71213*** 82.5*** 14140.3*** 15.9*** 14.9*** 1780.34*** 14095.4 *** genotype harvesting period 54 53*** 340* 0.84 259.5 0.12 0.14 38.47 467.1 residual 138 10.7 199 0.58 257.6 0.17 0.15 81.34 607.5 source of variation d.f. sca savp scp sndf sadf lca lavp lcp lnd f ladf replication 2 1.48 12.9 0.18 119.5* 98.4 56.6 3.7 7.6* 14.5 14.8 genotype 9 38.21*** 277*** 0.68** 14.2 31.6 58.5 287.5*** 3.3 15.9 137 residual 18 10.72 6.58 0.13 20.4 79.2 40.5 5.95 1.37 14.8 101.2 *significant at p<0.05 ** significant at p<0.01 *** significant at p<0.001 table 2: mean values of plant height (ph, cm), leaf number (lnpp), leaf length (ll, cm), leaf width (lw, cm), tiller number (tnpp), circumference (cf, cm) and leaf to stem ratio of napier grass genotypes, during 2018-2019 genotype ph (cm) lnpp ll (cm) lw (cm) tnpp cf (cm) lsr zehone_02(sc) 74.39bc 9.35bc 74.97de 2.86b 54.14b 180.07a 1.83 ilri_14982 70.34cd 10.14a 85.32a 2.47c 64.06a 174.39abc 2.06 ilri_16782 66.66cd 8.77de 78.13bcde 2.72bc 42.31cde 145.41de 1.89 ilri_16783 69.32cd 9.30bcd 74.20e 2.69bc 47.73bc 158.44bcd 2.17 ilri_16784 65.37cd 9.23bcde 82.02ab 3.02ab 46.18bcd 176.63ab 1.69 ilri_16800 67.42cd 8.95cde 76.56cde 3.29a 36.90de 139.52e 2.28 ilri_16817 63.91d 9.51b 77.79bcde 2.67bc 50.91bc 176.99a 2.62 ilri_16821 85.72a 9.69ab 81.54abc 2.78bc 35.56e 167.64abc 1.67 ilri_16835 83.77ab 9.46bc 80.18abcd 2.94ab 32.63e 157.22cde 1.71 ilri_16837 64.74cd 8.75e 76.68bcde 2.84b 33.94e 163.70abcd 2.15 lsd0.05 9.87 0.54 5.43 0.36 9.81 18.52 ns cv% 21.06 8.82 10.47 19.26 33.54 17.15 46.79 common letters in the column not statistically significant tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 5 in the test was in the range between 8.75 and 10.14. ilri_14982 genotype observed to have highest leaf number than other genotypes in the experiment. leafy plants could have lower lignifications and preferred as better animal feed. longer leaf and highest number of tillers per plant was observed for ilri_14982 while wider leaf was for ilri_16800 when comparing to standard check. circumference of the plant was wider for standard check (zehone_02) which was at par with ilri_16817. dry matter yield dry matter yield obtained from a total of seven harvests (january 2019 – november 2019) per year in the current study was varying from 66.98 t/ha to 128.89 t/ha among genotypes with mean of 92.34 t/ha. zehone_02 variety yields better than other varieties in the test followed by ilri_16835. the dynamics of herbage dry matter yield during the growing period was presented in table 2. the mean dry matter yield at first harvest in january 2019, after 120 days of planting, was 15.35 t/ha. the trend was decreasing to 8.18 t/ha at march 2019, increased to 13.18 t/ha in may and 17.35 t/ha in june 2019 and then consistently dropping to the last harvest in november. dry matter yield improved (table 3) with wet season and residual moisture as higher as 17.35 t/ha in june while dry season decreased yield of the grass as lower as 4.87 t/ha. forage nutritional quality stem and leaf quality of napier grass genotypes evaluated in terms of calcium (ca), phosphorus (p), crude protein (cp), acid detergent fiber (adf) and neutral detergent fiber (ndf) is presented in table 4. stem calcium, phosphorus and crude protein content of the grasses were significantly (p<0.001) varied among genotypes through the production period while no significant variation was observed for neutral detergent fiber and acid detergent fiber. the mean value for stem ca, p and cp were ranging from 0.140.25, 0.20-0.52, and 1.01-2.50 %dm, respectively. ilri_16837 genotype has shown better content of stem calcium followed by zehone_02. phosphorus content was higher for zehone_02 genotypes in the experiment. content of leaf phosphorus was varied (p<0.01) from 0.18 to 0.47 %dm and crude protein 3.8 to 7.33% among genotypes in the test while no significant variation was recorded in terms of calcium, adf and ndf content. significantly (p<0.01) higher leaf phosphorus was recorded for ilri_16837 followed by ilri_16800 and ilri_16817 than other genotypes in the test and standard check was shown much lower leaf p content. leaf crude protein was lower (p<0.05) for ilri_14982 and ilri_16782 than others in the test. table 3: dry matter yield (dmy t/ha) from jan 2019 through nov 2019 by month of harvesting and genotype genotype january march may june july sept nov mean total zehone_02(sc) 21.34 14.31 17.09 21.20 14.13 12.18 8.54 18.4a 128.79 ilri_14982 15.3 7.85 12.32 17.00 10.55 6.09 4.25 12.73de 89.12 ilri_16782 13.66 5.33 11.27 14.65 9.07 5.53 3.31 11.18ef 78.26 ilri_16783 32.44 9.91 14.39 14.74 10.14 8.03 2.96 16bc 111.97 ilri_16784 9.25 6.03 10.34 14.98 10.86 7.19 3.25 9.61f 67.26 ilri_16800 13.11 7.83 10.16 13.08 8.80 5.01 3.63 11.34ef 79.38 ilri_16817 7.89 7.90 10.38 13.79 9.40 4.67 2.79 9.57f 66.98 ilri_16821 9.91 9.30 15.71 20.23 13.13 11.10 8.45 14.25cd 99.75 ilri_16835 16.6 8.57 17.72 26.58 16.6 12.56 7.02 16.86ab 118.05 ilri_16837 14.04 4.73 12.4 17.24 10.22 9.29 4.5 11.98e 83.86 mean 15.35b 8.18e 13.18c 17.35a 11.29d 8.17e 4.87f 13.19 92.342 lsd0.05: genotype (g) =1.998, months (m) =1.672, lsd0.05 of genotype by months interaction (gxm) =5.29; coefficient of variation (cv) = 24.8% tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 6 table 4: nutritional quality parameters of napier grass, during 2019 genotype sca (%dm) sp (%dm) scp% sadf% sndf% lca (%dm) lp (%dm) lcp% ladf% lndf% zehone_02(sc) 0.23ab 0.52a 1.43bc 55.13 75.40 0.38 0.18f 7.33a 50.47 73.73 ilri_14982 0.17de 0.30d 1.90ab 57.37 76.83 0.34 0.31d 5.1bc 50.33 71.57 ilri_16782 0.21bc 0.44b 1.010c 52.40 78.40 0.29 0.39bc 3.80c 45.07 71.9 ilri_16783 0.22b 0.32d 2.50a 60.70 73.47 0.39 0.21f 6.90ab 58.27 76.3 ilri_16784 0.14f 0.33d 1.00c 59.27 73.00 0.41 0.26e 5.63abc 34.3 70.23 ilri_16800 0.19dc 0.24e 1.03c 59.53 73.33 0.32 0.43a 5.53abc 52.9 76.53 ilri_16817 0.15ef 0.44b 1.50bc 58.73 78.63 0.37 0.41ab 6.10ab 43.8 71.6 ilri_16821 0.16ef 0.37c 1.30bc 63.63 77.50 0.42 0.37c 6.73ab 44.6 71.83 ilri_16835 0.15ef 0.20e 1.03c 62.00 74.33 0.41 0.36c 6.90ab 41.27 71.9 ilri_16837 0.25a 0.37c 1.23c 59.43 74.03 0.39 0.47a 6.0ab 43 69.77 lsd0.05 0.025 0.044 0.61 ns ns ns 0.042 2.01 ns ns cv% 7.83 7.24 25.21 15.13 5.98 17.06 7.15 19.53 21.68 5.29 sca= stem calcium content, sp=stem phosphorus content, scp=stem crude protein, sadf=stem acid detergent fiber, sndf=stem neutral detergent fiber, lca=leaf calcium, lp=leaf phosphorus, lcp=leaf crude protein, ladf=leaf acid detergent fiber, lndf=leaf neutral detergent fiber, sc=standard check 3.2.discussion 3.2.1. dry matter yield variability of the weather across the forage harvesting months in 2019 helped to evaluate the productivity of the napier genotypes under different growing conditions. this condition previously reported as the precipitation and temperature are the major factors affecting forage growth and development (garay et al., 2017). hence, the dry matter yield variation of genotypes for different harvesting interval in the present study was due to the differences in amount and distribution of rainfall received during the growth period. the moisture availability following the wetter season triggering development of root, tiller and shoot of napier grass and then dramatically increases the yield. yield variation due to seasonal weather variability was similarly presented by other scholars for different cool season and warm season forages (ritz et al., 2020) and napier grass genotypes (abuye tulu et al., 2021). in the farmers’ field condition at trial location, there is no trend of producing forages in intensive management using agricultural inputs and this experiment could point the way how we can produce high yielding forages like napier grass with minimum input in dry land agricultural system. total average dry matter yield of present result was 92.34 t/ha/year which could sufficiently feed 51 animals with body weight of 200 kg for 365 days (selk, 2020) with mean value of 13.9 t/ha/cut was by far better than other reports that for 10 accessions yielded 27.9 t/ha/year in 2016 and 39.7 t/ha/year in 2017 (abuye tulu et al., 2021), <10 t/ha for four accessions (tessema tesfaye et al., 2021) and 11.04 t/ha for ten varieties (gezahegn kebede et al., 2016) in ethiopia and 3.4-5.8 t/ha/cut for four cultivars (zailan et al., 2018) and 43.7-61.6 t/ha/year for nine varieties (halim et al., 2013) foresees. also in agreement with the yield report of 12.6-15.8 t/ha/cut (maleko et al., 2019) for four varieties of napier grass. 3.2.2. forage growth parameters growth parameters such as ph, lnpp, lw and length, tnpp and cf determine the amount of dmy while lsr demonstrates forage quality. dmy is a function of growth parameters like ph (maleko et al., 2019) in which forages possessing taller ph contributing higher cumulative dmy (halim et al., 2013). significant (p<0.01) mean ph variation for napier grass genotypes which was ranging from 63.91 to 85.72 cm in the present study was reported by other scholars (wangchuk et al., 2015). it was also recommended to feed napier grass to dairy cattle at the height of 60 to 100 cm (muia, 2000) which most fits the tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 7 present study result. leafy plants could have lower lignification and preferred as better animal feed (islam et al., 2003) especially for calves and lactating cows. napier genotype ilri_14982 was demonstrating higher number, longer leaves and the highest number of tillers per plant comparing to standard check and others in the test. circumference of the plant was wider for standard check (zehone_02) as previously reported in ethiopia (gezahegn kebede et al., 2019) and at par with ilri_16817. variation in tiller number (32.63-64.06 per plant) among genotypes in the present study was also previously reported for three cultivars that higher tiller could re-establish the lost photosynthetic area and maintaining basal area (wangchuk et al., 2015). 3.2.3. forage nutritional quality calcium and phosphorus mineral nutrition has significant economical and health importance on livestock production (aioanei and pop, 2013). forages which contain less than 0.11% of phosphorus and 0.20% of calcium are considered to be deficient in respective nutrients (gastler and moxon, 1944). calcium content of present study was ranging from 0.14 to 0.25% for stem and 0.29 to 0.42% for leaf while the stem phosphorus content significantly varied from 0.2 to 0.52% and leaf from 0.18 to 0.47% which better qualifies the requirement of nutrients. ilri_16837 genotypes demonstrated better in stem calcium and leaf phosphorus content comparing to standard check and other genotypes in the experiment. zehone_02 excels other genotypes in stem phosphorus content while lower in leaf phosphorus content. calcium and phosphorus content of the present result concurs with the ten years average forage grasses hay calcium content 0.71% and phosphorus 0.36% (peters and kelling, 2001).the cp% and dm yield picture out in determining the overall nutritional value of forage crops (abuye tulu et al., 2021). the cp in forage determines the productivity of ruminant animals and greater quality grass hay should exceed 8% of dm to meet maintenance requirement of the animal (uslu et al., 2018) while at below 6% possess lower quality (selk, 2020) and to support milk production from cows fed on napier grass with advanced maturity should be supplemented with 3% of protein (muia, 2000). in our present report the napier grass genotypes cp value was ranging from 3.8 to 7.33% for leaves with average of 6.02%. stem cp value was also ranging from 1.00 to 2.5% which is noted for its low quality for supplement of ruminant protein maintenance. the mean of leaf cp value nearly similar with other scholars report ranging from 7.3 to 11.9% (shinoda and kawashima, 2000) and 5.4 to 8.3% (abuye tulu et al., 2021). napier genotype ilri_16782 noted for its lower cp value among 10 genotypes. napier grass leaves for present study possess >6% cp which is intermediate cp quality for grass hay (selk, 2020) and similar with the previous report of determining the composition and digestible nutrients of leaves of napier grass harvested in a way to simulate grazing by cattle (kidder, 1945). no significant variation recorded for both leaf and stem ndf and adf contents. this was reported previously by other scholars for ndf (abuye tulu et al., 2021). comparatively leaves of napier grasses have lower ndf and adf content than stem part at harvesting. 4. conclusion the result of the present study demonstrated that zehone_02 variety produced better yield (8.54-21.34 t/ha average per cut 18.4) followed by ilri_16835 (7.02-26.58 t/ha average per cut 16.86) in terms of forage dry matter production while ilri_16817 the least (2.79-13.79 t/ha average per cut 9.57) from september 2018 through november 2019 under fluctuating weather (rainfall and temperature) condition in arba minch rift valley lowlands. zehone-02 variety showed higher stem ca and p and leaf cp while lower leaf ca and p. ilri_16835 genotype produced high dry matter yield with optimum stem and leaf nutrient composition. no statistically significant ndf and adf variation recorded among genotypes for either stem or leaf production in this study. this shows napier grass genotypes are expecting to produce similar fiber content for leaf or stem in the rift valley of arba minch. silage making, hay quality and animal preference could be warranted for the genotypes/accessions in the test prior to be included in variety verification process. the production also has to be tested for irrigation. farmers in the study area and in similar agro-ecology and weather condition could produce ilri_16835 genotype with zehone_02 variety for sustainable optimum dry matter and quality production of napier grass. tessema tesfaye et al. ethiop.j.sci.sustain.dev., vol. 9 (1), 2022 8 acknowledgment authors highly acknowledge arba minch agricultural research center for the contribution of researchers and supportive staff in data collection, field follow up, data analysis and reviewing progressive reports for development of this work. southern agricultural research institute also duly thanked for financial support. reference aioanei, n. m., & pop, i. m. 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(2018). yield and nutritive quality of napier (pennisetum purpureum) cultivars as fresh and ensiled fodder. journal of animal and plant sciences, 28(1): 63–72. 9 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu review paper nuclear science and technology as a part of ethiopia’s energy mix and sustainable development strategies: exploring opportunities and challenges girma kibatu1,, tilahun tesfaye2, abeba getu3, henok tesfaye4 1department of chemistry, bahir dar university, science college, p.o.box-79, bahir dar, ethiopia 2 addis ababa university, department of physics, addis ababay, ethiopia 3national liaison officer (nlo) of ethiopia to the international atomic energy agency (iaea), ministry of innovation and technology (mint), addis ababa, ethiopia 4st. paul’s hospital millennium medical college, addis ababa, ethiopia article info abstract article history: received 23 april 2022 received in revised form 15 june 2022 accepted 16 june 20221 ethiopia is rich in energy natural resources, but it has not sufficiently exploited this resource advantage for its economic growth. while the country is endowed with many untapped natural resources and opportunities for development, its socioeconomic development is not satisfactory. its citizens are energy poor and don’t have sufficient access to modern energy services. access to modern energy service is a development imperative. the current ethiopian government as a part of its multi layered activities in the ten years perspective plan (typp 2021-2030) has considered a nuclear power program (npp) to use nuclear science and technology applications in its energy mix and sustainable development strategies and is planning and preparing on infrastructure requirements for its effective implementation. this review focused on the role of nuclear science and technology in energy production and sustainable development; and analyses the status, challenges and issues in the ethiopian national nuclear program. the review sets out to discuss the main issues in a national nuclear program, nuclear energy management and nuclear knowledge management demands and strategies for its effective application in embarking countries. knowledgeable commitment to the nuclear science and technology program in developing countries like ethiopia can boost economic growth. keywords: nuclear science and technology nuclear power program; nuclear energy management nuclear knowledge management ethiopia 1. introduction ethiopia is rich in energy natural resources, but it has not sufficiently exploited this resource advantage for its economic growth. while the country is endowed with many untapped natural resources and opportunities for development, its socioeconomic development is not satisfactory as such. its citizens are energy poor and don’t have sufficient access to modern energy services. access to modern energy service is a development imperative. corresponding author, e-mail: girmakibatuberihie@gmail.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.471 international and regional development policies for the world and africa (the 2030 agenda sustainable development goals, 2015; the african union’s agenda 2063, 2013), and national development policies such as the ethiopia’s home-grown reform agenda and the ethiopia’s ten years perspective plan (typp 20212030) (ethiopia vision 2030, 2021) have all require the use of science, technology and innovation (sti) and plan to develop energy infrastructures as enabling means http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022.471 girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 10 to implement sustainable development and economic growth goals. the new government of ethiopia has made several reforms in different sectors and aimed to facilitate investment in major infrastructure projects in key sectors including the energy sector. the ethiopia’s national policies extended from the above visions such as the science, technology and innovation policy, the climate change resilient green economic policy (national science policy and strategy and ethiopia’s climate resilient green economy, 2021), the national energy policy (energy proclamation no. 810/2013) and the ethiopia’s 25 years power system master plan (2022-2037) (ethiopian electric power corporation, 2022; amsalu yalew, 2022) are also all aligned to support the use of sti and plan to develop modern energy infrastructures in ethiopia. the current government of ethiopia have expressed interest in working in a nuclear science and technology (nst) program, revitalizing the revitalizing its intentions for embarking into the peaceful use of nuclear science and technology in ethiopia for sustainable development. in june 2019, the government of ethiopia has launched a nuclear and science and technology program with international support from russia’s government and the international atomic energy (iaea). the country has decided to include the use of nuclear science and technology in its economic sectors and is now preparing infrastructures to support sustain and develop a successful nuclear program. the ethiopian government is now in the process of establishing institutional components for nuclear the infrastructures. the first of its kind, a national nuclear science and technology centre, a research reactor and a nuclear power plant to benefit the use of nst in electric, non-electric and non-power applications to different sectors in the economy are envisioned in ethiopia in the near future. the development of an effective and sustainable nuclear energy program requires the development of many critical infrastructural issues. the objective of this paper is to critically assess nuclear science and technology as a technology and its applications; and explore the status, the opportunities, the gaps and the challenges in the use of nuclear science, technology and innovation program in ethiopia. the main issues in the national nuclear program; such as the issues of nuclear energy management and nuclear education/nuclear knowledge management demands and strategies for the effective applications of a nuclear program in ethiopia are evaluated and recommendations have been suggested for successful development and implementation. 2. ethiopia’s socio-economic and political situations ethiopia, a country with a population of 115 million, is the second largest country in africa. although the country is endowed with a substantial land mass and untapped natural resource potentials, its present socioeconomic condition is not satisfactory and it remains today one of the least developed countries in the world (world bank report, 2022). although the country’s economy has showed progress in the 1980s and 1990s relatively; economic development in ethiopia has been beset with a continuing problem of balkanization and internal conflicts, lack of capacity in nation building, and political unrests due to lack of good governance. thus, a new form of government has been formed in 2018. the current ethiopian government has been learning from the development efforts in the 1980s and 1990s, and has redesigned a series of new policy measures to raise productivity in both private and public services including in the energy sector (fdre, 2018 and mowie, 2019). ethiopians, therefore, once again; under the new leadership have hopes and good reasons to enter the 2020s into accelerated growth with social justice. 2.1. energy systems scenario in ethiopia ethiopia is rich in potential energy resources, but its citizens are still energy poor and access to modern energy services is limited (world bank report, 2019). currently, the ethiopia’s per capita electricity consumption of 100kwh per year is the third-largest electricity access deficit in sub-saharan africa. the world bank report in 2019 indicates access to electricity in ethiopia stands at 44% and it is estimated that the demand would double in a decade. much of the electrification available is highly dependent on a single energy source –the hydropower, which is unreliable and sensitive to climate change which as a result causes shift services and outages. 2.2. development options under considerations the current government of ethiopia aims to achieve universal 100% access to electricity by 2030 and achieve goal 7 of the united nations sustainable girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 11 development goals. ethiopia’s 25 years power system master plan (2022-2037) also aims to generate up to 37,000 mw of power by the year 2037. energy is essential for development (iaea, 2001). ethiopia aims to achieve its vision through major scientific and technological projects in hydropower, solar, wind, and geothermal projects in the pipeline. the government of ethiopia has also shown interest to commence a nuclear program for the peaceful applications of nuclear science and technology as one of the strategies to achieve its targets in both in its energy mix and sustainable development goals. 3. nuclear science and technology nuclear science, technology and innovation are a multidisciplinary and highly specialized area of science and technology that involves nuclear reactions of atomic nuclei (murogov, 2019). in nuclear physics and nuclear chemistry, a nuclear reaction is semantically considered the process in which fission or fusion reactions produce one or more nuclides that are different from the nuclide(s) that begin the process. a notable example of a fission reaction of uranium-235 by accelerated neutron as shown below show results in a single nuclear reaction that can generate 200mev energy. in addition to the kinetic energy that is used for electrification, the heat from the reaction, the radioisotopes (radionuclides), the neutrons (sub atomic particles) and the photons of gamma radiation produced in nuclear reactions have been harnessed in various applications. applications of nuclear science and technologies in energy, food and agriculture, health and medicine, manufacturing and industry, water resource management and in the sustainable environment management play significant roles in driving socioeconomic and sustainable growth of a society. 3.1. brief history of nuclear science and technology the science of atomic radiation, nuclear change and nuclear fission was developed from 1895 to 1945, much of it in the last six of those years (world nuclear association, 2022). over the years from 1895-1945 most development was focused on atomic bomb development. the years 1946-1956 was dedicated to the development of nuclear power plants for electrification. since 1956 the prime focus has been on technological evolution to reliable nuclear power plants and progress in non-electric and non-power application of nuclear science in other sectors other than electricity production. scheme 1: schematic diagram for fission reaction resulting in excessive heat, transmutation (radioisotopes), subatomic particles (such as n neutrons) and gamma radiation. 3.2. nuclear fuel cycle the various activities associated with the production of electricity from nuclear reactions are referred to collectively as the nuclear fuel cycle. the nuclear fuel cycle is the series of industrial processes which involve the production of electricity from uranium in nuclear power reactors (iaea, 2022). the nuclear fuel cycle has the following processes and activities: uranium mining; uranium refining and conversion; uranium enrichment; fabrication of nuclear fuel; and electric generation at nuclear power plant. fuel removed from a reactor, after it has reached the end of its useful life, can be reprocessed to produce new fuel. the nuclear fuel cycle starts with the mining of uranium and ends with the disposal of nuclear waste. 3.3. uranium geology exploration and resources in ethiopia ethiopia has prospective geology with mining potentials for certain minerals (getaneh assefa et. al. 1991). in a report from an old newspaper on may 15 1954 – the emperor haile selassie announced that some of the best uranium ore in the world had been discovered in ethiopia (new york times, may 15 1954). an outcome of a recent two-year survey on the prospect for mineral resources across ethiopia, identified uranium among several other minerals in six weredas of the eastern region, including harar, kersa, babile, girawa, midaga, and faddis (geological survey of ethiopia, ministry of mines and energy, 2021 ). however, further research is needed providing technical assistance to help girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 12 survey uranium mines in ethiopia, to get a better idea of how much uranium ore in ethiopia is economically feasible. 3.4. applications of nuclear science and technology in the course of developing nuclear weapons, nuclear scientists and technologists in the soviet union and the west had acquired a range of new nuclear technology applications. 3.4.1. power applications of nuclear technologies electric applications: inside a nuclear power reactor the fissile nuclei of atoms split (fission) and, in the process, release energy. figure 1: overview of the nuclear fuel cycle. this energy is used to heat water and turn it into steam. the steam is used to drive a turbine connected to a generator which produces electricity (us doe, www.energy.org/ne, 2022). as with as a coal-fired power station; about two thirds of the heat is dumped either to a large volume of water (from the sea or large river, heating it a few degrees) or to a relatively smaller volume of water in cooling towers, using evaporative cooling (latent heat of vaporisation). the main reasons for a nuclear power option for electrification is that it is a reliable, high base load green energy source, carbon free/greenhouse gas (ghg) emission free electricity/ and by far resilient for climate change. some concerns in this technology include high upfront cost, highly qualified human resources, and radioactive waste, safety and security issues. non-electric applications: commercial reactors are now offering various applications beyond providing electricity for homes and businesses (iaea. 2022; rosen, 2021). nuclear technologies can now be used in water desalination, provide heat for metal refining, and can even be used to generate hydrogen as a clean burning alternative fuel for vehicles. industries in hydrogen production; water desalination; process heating; district heating; nuclear powered-ship and rocket propulsion; and cooling and refrigeration machines could leverage nuclear processes heat and non-stationary power reactors to further help decarbonise human activities in our society. 3.4.2. non-power applications of nuclear technologies the applications of nuclear technology outside of civil electricity production in power plants and nonelectric application from nuclear process heat and nonstationary nuclear reactors are less well-known (fujjie, 1995). radioisotopes and gamma radiations produced in the nuclear processes in nuclear reactors, accelerators and or generators have also essential uses across multiple sectors including in food and agriculture, medicine, industry and consumer products, water resources and the environment, in arts and society, and scientific research (walter, 2003). 3.5. nuclear science and technology in ethiopia 3.5.1. the ethiopian nuclear and radiation protection authority the ethiopian nuclear and radiation protection authority (enrpa) is an established national regulatory control body to control the use of ionizing radiation sources in ethiopia since 1993. the ethiopian parliament has also ratified legal requirements that are meant to upgrade the scope of the ethiopian regulatory body into the coming activities following a nuclear program in 2017. the new nuclear and radiation protection proclamation (proclamation no. 1025/2017) includes provisions on radioactive waste management. continuous develop mental work, matching the progress of the program, is expected from the national regulatory body. girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 13 figure 2: typical nuclear power plant. 3.5.2. medical agricultural and industrial applications of nuclear technology in ethiopia the application of nuclear techniques in ethiopia started in the early sixties in the medical field and has gradually expanded to other areas such as agriculture, animal health and research, hydrology, mining and industry. ethiopia has only one public radiotherapy centre at black lion specialized hospital in addis ababa for the whole country (demena, 1993; 2002). the tsetse fly eradication project using radiation technology in the rift valley, and plant breeding project using radiological methods to improve teff varieties in debere ziet are the main endeavors in the ethiopian national agricultural research centres (alemu et. al. 2007). nuclear measuring and detecting devices have been used for gauging in different beverage, construction, and transport industries and customs services. 3.5.3. education research and educational networks in nuclear science and technology in ethiopia there are only a few nuclear education and training programs in the education system in ethiopia (belete, 2004). physical components like facilities and training and research institutions are at their primary level. some universities in ethiopia are running msc program in nuclear and radiation physics. the addis ababa university has a phd program in nuclear physics. the addis ababa science and technology university has established a centre for nuclear reactor technology. apart from training in traditional sciences, engineering and medicine students there are no universities running nuclear and radiological sciences, nuclear engineering and technology, or nuclear medicine and radiopharmaceutical programs in the country. 4. the ethiopian nuclear power program 4.1 the iaea milestones approach the international atomic energy agency (iaea) has developed an internationally accepted method to implement sustainable nuclear power programs for newcomer countries considering launching a nuclear power program in their development (noh and kim, 2016). a nuclear power program is a major undertaking requiring careful planning, preparation and investment in time institutions finances and human resources. the iaea milestones approach enables a sound development process for a nuclear power program. the milestones approach helps the country understand its commitments and obligations to ensure its npp is safe secure and sustainable. the milestones approach is documented in the iaea nuclear energy series publication. 4. 2. nuclear energy management three key organizations are involved in building a nuclear power program (danesi, p.r., 2011). the government should create a mechanism for example a nuclear energy programme implementing organization (nepio) to coordinate the work all organizations involved, a competent, independent regulatory must be developed to ensure it that it combines with all nuclear girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 14 safety standards. the owner/operator may be state owned or private and must be competent to safely operate the nuclear power plant and meet regulatory requirements. 4.3. the status and development of nuclear program in ethiopia ethiopia’s nuclear journey started with vision and inspiration of previous governments to develop and promote the peaceful use of nuclear science and technology in the fields of energy, medicine, water and agriculture. ethiopia's current government commitment to pursue nuclear energy is also a part of efforts to reduce dependence on fossil fuels, diversify its energy sources and adapt to climate change (amanuel, 2020). although ethiopia has not drafted an independent national nuclear policy, the policies such as the typp, national energy policy, the national strategy of climate resilient green economy, sit policy, and the national energy master plan all provide an overall framework and guide to the need to the implementation of a nuclear program. it can also be taken as a policy base to strengthen the legal, institutional, and operational framework of nuclear science and technology in the country. two agencies; a nuclear energy programme implementation unit (nepio/national nuclear science and technology task force) in the ministry of innovation and technology as a promoter planner and organizer to the national nuclear program and an ethiopian nuclear and radiation protection authority as a regulatory body are now guiding and work on regulating services pertaining to the national nuclear program ethiopia. the ethiopian nuclear program also enjoys bipartisan support from technology providers. ethiopia’s national nuclear program has two parts. the first phase of the country’s nuclear program aims to set up a national center for nuclear science and technology with nuclear research reactor and other facilities for comprehensive services in non-electric applications and training and research needs by 2024. the second part of the country’s nuclear program is a nuclear energy program to introduce nuclear energy into ethiopia’s energy mix. the country is currently considering both large and small modular reactors for its nuclear energy. the country is currently considering implementing large research reactor program in a national centre for nuclear science and technology in the near future and has set a target of 2035-2040 to have its first nuclear power plant up and running. the evaluation of the status of the ethiopian nuclear energy program using the iaea’s milestone approach; the timeline shows that ethiopia is now in phase i. the country has already taken some decision measures to include nuclear in its future energy mix. the country currently is undergoing feasibility study and is also in parallel planning for the development of other infrastructures needed for an effective program and may hit the milestone i at in this year 2022. key government decisions have been made based on policies and recommendations from the nepio, the national regulatory body, the technology vendor and the international atomic energy agency. with the guidance from the national agencies and an intergovernmental cooperation, the government of ethiopia has taken both the cabinet and the parliament to decisions to introduce a national nuclear program in 2021. ethiopia’s decision to embark into the nuclear program however; has not been supported by strong policy justification strategic documents and missions (a national nuclear policy, pre-feasibility study for a national nuclear program, a national nuclear power roadmap, a nuclear programme implementation plan, request for information issued to seek both technical, financial and contractual information from the vendor countries regarding the technology they intend to deploy to ethiopia and; the iaea integrated nuclear infrastructure review (inir) mission). these documents and missions are either under consideration or yet to be produced for a strong policy justification and commitment from all stakeholders involved in the project. 4.4. concerns/challenges on the national idea on nuclear power program newcomer countries like ethiopia embarking into a new nuclear energy power programs with little experience in the science and technology usually face some concerns to implement an effective affordable and large sustainable development projects in the energy sector. some of the important issues, concerns and challenges raised in the national nuclear program are included in the following list: national position and capacity building; finances and funding schemes; human resource development; nuclear energy management; legislative and regulatory framework; national electrical grid; accidents and security treats; girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 15 radioactive waste and limited fuel supply; and public opinion and awareness (adams and odonkor, 2021 and karim et al., 2018). the evaluation of status of these challenges and concerns in the ethiopian nuclear program based on the international practice and guidelines for the development of a nuclear program for embarking countries show gloomy situations in these areas (endalew, 2021). the success of the program is highly dependent on how these challenges and issues are addressed properly on time, 4.5. nuclear capacity building and education in ethiopia for countries looking to implement nuclear energy and leverage all other potential applications of nuclear science and technology; capacity building in knowledge management, education and training are important part in the development of the nuclear science and technology programs. 4.5.1. nuclear knowledge management knowledge management is an integrated, systematic approach for identifying, acquiring, transforming, developing, disseminating, using, sharing and preserving knowledge relevant to achieving specific objectives (iaea tecdc-1510. 2022). countries with existing nuclear programs need to secure the capacities and human resources necessary to sustain the safe operation of existing installations, including their decommissioning and related programs for spent fuel and waste. 4.5. 2. stem education coupled with humanity and arts in an ever-changing, increasingly complex world, it's more important than ever that the young generations are prepared to bring knowledge and skills to solve problems, make sense of information, and know how to gather and evaluate evidence to make decisions. these are the kinds of skills that students develop in science, technology, engineering, and math, including computer science, humanity and arts—disciplines collectively known as stem (the us national academies of science engineering medicine, 2018) 4.5. 3. systematic approach for training training is a planned process that directs learning towards achieving specific outcomes, leading to achieving performance objectives. the systematic approach to training infers that training is done in a planned, systematic way and that it is directed towards improving job performance (al-moayad, 2019; iaea’s systematic approach to training for nuclear facility personnel: processes, methodology and practices. 2022). for any training program in nuclear education and training to be successful it is very essential to follow a certain process. training can be viewed as a process comprised of five related stages or activities: assessment, motivation, design, delivery, and evaluation. 4.5.4. competence based practice oriented program competency-based training refers to a learning model where students must demonstrate the required level of knowledge and skill (competency) on a task prior to advancing to the next task (iaea. 2014). the competency-based education (cbe) approach allows students to advance based on their ability to master a skill or competency at their own pace regardless of environment. this method is tailored to meet different learning abilities and can lead to more efficient student outcomes. 4.5.5. curriculum development proposal for nuclear science and engineering developments of educational programs and curriculum development activities by some universities in ethiopia have shown some developments in integrating nuclear education in their education base. the addis ababa technology university has established a research sector in nuclear power technology and have initiated a research reactor acquisition project for the development of the centre. a project by bahir dar university to integrate nuclear education in its education base has developed and proposed a new msc joint curriculum (murogov et al., 2009) in nuclear science and engineering between the college of science and bahir institute of technology. 4.5.6. international regional and national educational networks for nuclear knowledge the international atomic energy agency is the world’s central intergovernmental forum for scientific and technical co-operation in the nuclear field. cooperation with international, regional and national nuclear education networks provide solutions, best practices and lessons (murogov et al., 2009). the national educational network in ethiopia has not been properly organized so far. in ethiopia there are many balkanized educational societies that are related to nuclear girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 16 scheme 2. a program structure proposed curriculum for an msc in nuclear science and engineering module 1 nuclear and radiation physics; module 2 nuclear chemistry and materials; module 3 nuclear power technology; module 4 nuclear technology in non-power applications; module 5 nuclear safety security and safeguard’; module 6 mathematics computer science and social sciences/humanities and arts. science and technology of which each of them fail into an overlapped mission and single goal. it may be better to bring stakeholders in the field into one national society ‘the ethiopian nuclear society’ and establish a national nuclear network for education in science and technology; ‘the ethiopian nuclear-nest’ bringing stakeholders in nuclear industry in one bigger society as umbrella society with divisions and sub divisions depending on the needs. 5. conclusions and recommendations this review set out to discuss why the peaceful use of nuclear science and technology makes sense in an ethiopian context. economic and environmental considerations point to the use of nuclear power generation as a viable option to include in the energy mix of ethiopia and to accelerate sustainable development. the peaceful use of the nuclear fission process not only play a role in nuclear power generation but also in non-electric and non-power applications in medical agricultural and industrial sectors that can boost socioeconomic development. the iaea has introduced stricter oversight and regulatory instruments to assist countries. ethiopia, therefore, needs to be an active participant in the nuclear field, and not just an observer. alternative sources of electrical power generation are currently attracting more attention, primarily due to the need for reliable energy source to support the economic growth, global demands for sustainability and environmental considerations. ethiopia should strive to have as robust an energy mix as possible, taking advantage of its renewable and non-renewable clean resource endowment. a cooperative approach between ethiopia and the international, regional and local organizations and industry and educational networks could assist in gathering critical mass for developing nuclear as a viable source of energy. as nuclear technology is highly regulated, ethiopia also needs to develop robust infrastructures for the national nuclear program. . nuclear and radiation engineering and technology civil mechanical electrical and environmental engineering nuclear and radiological science nuclear and radiation physics, nuclear chemistry and radiochemistry, radiation chemistry and materials, radiobiology and radioecology and environmental radioactivity module 6 module 1 module 2 module 3 module 4 module 5 girma kibatu et al. ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 17 reference adams, s. and odonkor, s. 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(2020). techno economic analysis for construction and operation of nuclear power plants in ethiopia. an m.sc. thesis, bahir dar energy center, bahir dar institute of technology, bahir dar university world nuclear association (2022) online history of nuclear energy (updated november 2020) y. fujjie (1995) nuclear science and technology in the 21st century. progress in nuclear energy, 29: 3-9. 20 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 machine learning prediction of human activity recognition getinet yilam and dileep kumar school of electrical engineering and computing: computer science & engineering program. *corresponding author e-mail: getyilma@astu.edu.et abstract wearable computation is getting integrated into our daily life. it has got wide acceptance due to their small sizes, and reasonable computation power. these wearable devices loaded with sensors are good candidates to monitor user’s daily behavior (walking, jogging, sleeping…). human activity recognition (har) has the potential to benefit the development of assistive technologies in order to support care of the chronically ill and people with special needs. activity recognition can be used to provide information about patients’ routines to support the development of e-health systems, like ambient assisted living (aal). despite human activity recognition being an active field for more than a decade; the development of contextaware systems, there are still key aspects that, if addressed, would constitute a significant turn in the way people interact with mobile devices. the study discusses the principal issues and challenges of har systems. a general and data acquisition architecture for har systems are presented. har systems made use of machine learning techniques and tools, which are helpful to build patterns to describe, analyze, and predict data. since a human activity recognition system should return a label such as walking, sitting, running, etc., most har systems work in a supervised fashion. the objective of proposed study is applying multiple machine learning algorithms on the har dataset from groupware. out of the 5 machine learning algorithms that random forest yields the highest accuracy in predicting activities correctly, results showed the accuracy of 100%. all the models were also ensembled to improve overall accuracy. keywords: human activity recognition, wearable computing, machine learning, iot, r. 1. introduction internet of things (iot) is "a network of interconnected things/ devices which are embedded with sensors, software, network connectivity and necessary electronics that enables them to collect and exchange data making them responsive." – wiki. iot is "a network of items each embedded with sensors which are connected mailto:getyilma@astu.edu.et getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 21 © adama science & technology university https://ejssd.astu.edu.et to the internet." ieee definition. itu has pointed out 4 dimensions of iot: tagging things identification of objects using rfid, bar code, gps, accelerometer etc., feeling things through sensors, near field communication (nfc) and wireless sensor networks, thinking things using embedded systems and special instructions, shrinking things using nanotechnology. according to idc, within 2020, the number of things connected to the internet will be about 50 billion and the world’s data will amount to 44 zettabytes by 2020, 10% of it from the internet of things which makes the amount of data generated from iot tremendous [1]. recently, wearable devices such as smart watches, google glasses, fitness trackers, sports watches, smart clothing, smart jewelry, implantable etc. have got a lot of interests and wide acceptance due to their small sizes, reasonable computation power, and practical power capabilities. these wearable devices loaded with sensors (e.g. accelerometer, gyroscope) provide a good candidate to monitor user’s daily behavior (e.g. walking, jogging, and smoking). recent advancement of wearable technology has resulted in utilization of wearable and nonintrusive systems for health and activity monitoring. such continuous monitoring of life and daily activities, motivate the users to maintain healthy living style. wearable device can comprise 4 tri-axial adxl335 accelerometers connected to an atmega328v microcontroller [2]. the accelerometers can be positioned in the waist [1], left thigh [2], right ankle [3], and right arm [4]. all accelerometers have to be calibrated prior to the data collection. the calibration consists of positioning the sensors and the performance of the reading of getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 22 © adama science & technology university https://ejssd.astu.edu.et values to be considered as "zero"’. from the calibration, the read values of each axis during data collection are subtracted from the values obtained at the time of the calibration [3-4]. machine learning (ml), algorithms, tools and techniques are helpful to build patterns to describe, analyze, and predict data. in a machine learning context, patterns are to be discovered from a set of given observations denominated instances. such input set is training set [5] the paper is organized as the following: section ii presents related work, section iii discusses har and its techniques, section iv presents experimentation in r and results obtained. 2. related work up to now, there have been many studies related to human activity recognition. machine learning based methods that have been previously employed for recognition include naive bayes, svms, threshold-based and markov chains [5]. although it has been not fully clear which method performs better for ar, svms have confirmed successful application in several areas including heterogeneous types of recognition such as handwritten characters [6] and speech [7]. in ml, fixed-point arithmetic models have been previously studied [8-9] initially because devices with floating-point units were unavailable or expensive. the possibility of retaking these approaches for ami systems that require either low cost devices or to allow load reduction in multitasking mobile devices has nowadays become particularly appealing. anguita et al. in [10] introduced the concept of a hardware-friendly svm (hfsvm). this method exploits fixedpoint arithmetic in the feedforward phase of the svm classier, so as to allow the use of this getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 23 © adama science & technology university https://ejssd.astu.edu.et algorithm in hardware-limited devices. 3. human activity recognition the recognition of human activities has become a task of high interest, especially for medical, military, and security applications. for instance, patients with diabetes, obesity, or heart disease are often required to follow a welldefined exercise routine as part of their treatment [11]. har has the potential to benefit the development of assistive technologies in order to support care of the elderly, the chronically ill, monitoring energy expenditure and for supporting weight-loss, programs digital assistants for weight lifting exercises, and people with special needs. example using smart homes to detect and analyze health events is given below. figure 1: smart home based health data analysis [2] the home supportive environment delivers trend data and detection of incidents using non-intrusive wearable sensors. this facilitates a quick measurement and fast acceptance at the same time. through real-time processing and data transmission, healthcare suppliers will be able to monitor the subject’s motions during daily activities and also to detect unpredictable events that may occur, like a fall. the subject’s records can be used in medical decision support, in prediction and prevention of accidents [12-14]. the two approaches commonly used for har are (1) image processing with computer vision and (2) use of wearable sensors. the image processing approach does not require the use of equipment in the user’s body, but imposes some limitations such as restricting operation to the indoor environments, requiring camera installation in all the getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 24 © adama science & technology university https://ejssd.astu.edu.et rooms, lighting and image quality concerns and user privacy. but, the use of wearable sensors minimizes these problems even though they require users to wear the equipment through extended periods of time. hence, the use of wearable sensors may lead to inconveniences with battery charges, positioning, and calibration of sensors. table 1: some of the activities recognized by har systems are given as follow 4. applying machine learning similar to other machine learning applications, activity recognition requires two stages, i.e., training and testing (also called evaluation). the training stage initially requires a time series dataset of measured attributes from individuals performing each activity. the time series are split into time windows to apply feature extraction thereby filtering relevant information in the raw signals. later, learning methods are used to generate an activity group of activities activities ambulation walking, running, sitting, standing still, lying, climbing stairs, descending stairs, riding escalator, and riding elevator. transportation riding a bus, cycling, and driving phone usage smsing, making a call. daily activities eating, drinking, working at pc, reading, watching tv, brushing teeth, stretching, scrubbing and vacuuming. exercise/fitness rowing, lifting weights, spinning, nordic walking, and doing pushups. military crawling, kneeling, situation assessment, and opening a door upper body chewing, speaking, swallowing, sighing and moving the head. others heartbeat, respiration, temperature, location, contraction, and etc. getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 25 © adama science & technology university https://ejssd.astu.edu.et recognition model from the dataset of extracted features. likewise, for testing, data are collected during a time window, which is used to extract features. such feature set is evaluated in the priory trained learning model, generating a predicted activity label. figure 2: machine learning approach based on wearable sensors generic data acquisition architecture: in the first place, wearable sensors are attached to the person’s body to measure attributes of interest such as motion, location, temperature, and ecg, among others. these sensors should communicate with an integration device (id), which can be a cellphone, a pda, a laptop, or a customized embedded system. the main purpose of the id is to preprocess the data received from the sensors and, otherwise send raw signal to an application server for real time monitoring, visualization, and/or analysis. the communication protocol might be udp/ip or tcp/ip, according to the desired level of reliability. figure 3: general data collection process for har har systems make use of machine learning (ml) tools, which are helpful to build patterns to describe, analyze, and predict data [15]. it is used to classify the local data physiological signals acceleration signals feature extraction learning and inference model building recognize activity collect data getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 26 © adama science & technology university https://ejssd.astu.edu.et mistakes in activity recognition. in a machine learning context, patterns are to be discovered from a set of given examples or observations denominated instances. such input set is called training set. each instance is a feature vector extracted from signals within a time window. the examples in the training set may or may not be labeled, i.e., associated to a known class (e.g., walking, running, sleeping etc.). in some cases, labeling data is not feasible because it may require an expert to manually examine the examples and assign a label based upon their experience. this process is usually tedious, expensive, and time consuming in many data mining applications. since a human activity recognition system should return a label such as walking, sitting, running, etc., most har systems work in a supervised fashion. indeed, it might be very hard to discriminate activities in a completely unsupervised context. some systems work in a semi supervised fashion allowing part of the data to be unlabeled. 5. implementation and results in general, the selection of the classification algorithm for har has been merely supported by empirical evidence. the vast majority of the studies use cross validation with statistical tests to compare classifier’s performance for a particular dataset. the classification results for a particular method can be organized in a confusion matrix mnxn for a classification problem with n classes. this is a matrix such that the element mij is the numbers of instances from class i that was actually classified as class j. the following values can be obtained from the confusion matrix in a binary classification problem:  true positives (tp): the number of class a activities that were classified as class a.  true negatives (tn): the number of non class a getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 27 © adama science & technology university https://ejssd.astu.edu.et activities that were classified as non class a.  false positives (fp): the number of non class a activities that were classified as class a.  false negatives (fn): the number of class a activities that were classified as non class a. table 2 classification algorithms for har. the accuracy is the most standard metric to summarize the overall classification performance for all classes and it is defined as follows: accuracy = 𝑇𝑃 + 𝑇𝑁 tp + tn + fp + fn … … 1 we used r for our experimentation. r is a free, open source language with highly active community members available across all platforms (linux, mac, and windows). due to its underlying philosophy and design; r is useful for statistical computation and graphic visualization [16]. the goal of this study is to build a model that can predict the type of activity or exercise listed in table 1 above performed based on measurements of human movement. we used machine learning techniques to build a model to predict the manner of the exercise, "classes", based on a variety of collected information. machine learning algorithms are applied on the human activity recognition dataset from type classifier decision tree cd4.5, id3 bayesian naïve bayes and bayesian networks instance based k-nearest neighbors neural network multi-layer perceptron domain transform support vector machines markov models mlr, alr classifier ensembles boosting and bagging getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 28 © adama science & technology university https://ejssd.astu.edu.et groupware. out of five ml algorithms, which are bagging with classification trees, logistic regression, support vector machines, random forest, gradient boosting model and classification trees, random forest yields the highest accuracy rate of 100%. the entire models except classification tree are ensemble to give a better prediction. the final outcome has shown 98% accuracy rate on the 20 testing data point. dataset: the data used in this analysis is the human activity recognition dataset (weight lifting exercise), provided by groupware [17]. the dataset consists of 19,622 observations of 160 variables that describe subjects and their physical movement during activities. the approach for the weight lifting exercises dataset is to investigate "how (well)" an activity was performed by the wearer. the "how (well)" investigation has only received little attention so far, even though it potentially provides useful information for a large variety of applications, such as sports training. six young health participants were asked to perform one set of 10 repetitions of the unilateral dumbbell biceps curl in 5 different fashions [17]:  exactly according to the specification (class a),  throwing the elbows to the front (class b),  lifting the dumbbell only halfway (class c),  lowering the dumbbell only halfway (class d) and  throwing the hips to the front (class e) [17]. data loading: firstly, we loaded the data into memory using the following data preprocessing: many of the entries in the observation contain nas (not applicable) values. we excluded columns that have nas from the table, as these columns will not add getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 29 © adama science & technology university https://ejssd.astu.edu.et any useful information to the model that we build. this reduces the number of columns from 160 to 60. data analysis: now, started to analyze our data, step 1: split the data into training testing data. notice that the ratio of training data to testing data is 0.8 reduce variance and increase performance. before applying machine learning algorithms to train our model, first the cross-validation parameters were tuned. out-ofsample error was low because 5fold cross validation takes its effect and avoid over fitting. step 2: train models with the training data using 6 chosen machine learning algorithms. bagging with trees: this gave a very high accuracy rate, 99.92% logistic regression with boosting: this model gave 96.51% accuracy rate, an efficient model as well. support vector machines with boosting: getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 30 © adama science & technology university https://ejssd.astu.edu.et this model gave 93.75% accuracy rate. random forest: this model gave 100% accuracy rate. generalized boosting regression model (gbm): this model gave 99.75% accuracy rate. classification tree algorithm: this model had given 85.5% accuracy rate. all models are evaluated, now we turned to ensemble them. step 3: ensemble learning algorithms & predict table 3: prediction variable and respective algorithms description variable algorithm pred1 bagging with tree pred2 logistic regression with boosting pred3 support vector machine pred4 random forest pred5 generalized boosting regression model ensemble result [b, a, b, a, a, e, d, b, c, b, a, e, e, ab, b, b] with ensemble accuracy 98% and 0.02 error. here we can see the final outcome; note pred4 has much higher accuracy than any other getnet y.& kumar. d. ethiop. j. sci. sustain. dev., 5 (1), 2018 31 © adama science & technology university https://ejssd.astu.edu.et predictors. table 4 gives the rules to pick out that final answer: if all 5 models give the same answer, that’s definitely the correct answer. if not, compare the results of others, and pick the one that gives higher class value. if all 5 give different answers, follow the one pred4 i.e. random forest gives which is 100% accurate. so here we get the final answers, which reportedly 98% accuracy rate on the final outcome. table 4: ensemble result 6. conclusions and future work the paper studied human activity recognition techniques and presented the general data collection process for har and also the machine learning based data analysis process using r out of the 5 ml algorithms that are applied, the random forest method yielded 100% accuracy over the other methods. a next step in this path would be to store real-time sensor data and analyze.to provide real-time recommendation to users. references: [1]http://www.computerweekly.co m/news/2240217788/dataset-to-grow-10-fold-by2020-as-internet-of-thingstakes-off [2] adam thierer. “the internet of things and wearable technology: addressing privacy and security concerns without derailing innovation.” mercatus working paper, mercatus center at 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[16] https://www.r-project.org/ [17] http://groupware.les.inf.pucrio.br/har 59 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper prediction of bearing capacity of fine grained soils from field dynamic cone penetration reading: case of clayey soil from asella, ethiopia kemal abdela1, yadeta c. chemeda2,* 1bule hora university, college of engineering and technology, civil engineering department, p.o. box 144, bule hora, ethiopia 2adama science and technology university, school of applied natural sciences, department of applied geology, adama, ethiopia * corresponding author, e-mail: yadeta.chemdesa@astu.edu.et abstract bearing capacity is one of the important parameters that needs to be considered for design and construction of foundations of civil engineering structures. the conventional method of estimating this parameter is commonly using terzaghi’s equation, which requires the shear strength parameter of soil. shear strength test is expensive and time consuming, hence convent ional method of estimating bearing capacity is uneconomical especially for small scale projects. dynamic cone penetrometer (dcp) is one of the simple in situ test methods widely used in site investigation for estimating the strength and density of soils. this work is, therefore, aimed at predicting bearing capacity of shallow foundations from field in situ dcp reading for fine grained soils of asella town, ethiopia. the soil index properties and tri-axial tests to determine the shear strength parameters were performed on soil samples extracted from different pits. on the same pits, dcp test have been performed in the field to record d-value (mm/blow). then, regression analyses have been performed to determine relationship of allowable bearing capacity (qall) with d-value and index properties. regression analyses results showed that qall have strong relation with d-value having coefficient of determination (r2=0.89) than index properties. the footing dimension have no effect on the predicted bearing capacity of foundation. the comparison between the developed equation and the actual qall obtained from terzaghi’s bearing capacity equation shows average variations of 11.7%, suggesting the validity of the developed equation. keywords: dynamic cone penetration, bearing capacity, shallow foundation, shear strength, correlation 1. introduction the causes of failure of light weight engineering structures built on clayey soils are mostly related to the expansive nature of the soils (bell, 1996). improper estimation of bearing capacities of the soil mass can also lead to failure. on the other hand, underestimation of soil load carrying ability leads to increase of cost of project unnecessarily. bearing capacity is, therefore, one of the important parameters to be accurately investigated for design of foundations of civil engineering structures (bowles, 1993). in conventional approach, bearing capacity of foundation soil is mostly calculated from terzaghi’s bearing capacity equation (murthy, 2007), which requires the shear strength parameters such as cohesion (c) and angle of internal friction (ф). tri-axial compression test is a widely used method to measure the shear strength parameters of a soil in the laboratory by controlling confining stress and drainage condition. the aforementioned method, however, requires relatively more time, effort as well as money. therefore, it may not be economical for small engineering projects such http://www.ejssd.astu.edu/ mailto:yadeta.chemdesa@astu.edu.et kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 60 as in residential house development. in light of these challenges, there is a need to find time and cost effective ways that can replace shear strength parameters for determination of bearing capacity of shallow foundation for light structures. in addition, the application of field tests for site investigation are important for professional engineers since present practice is to rely more on field tests. the in situ field test can avoid some of the problems of sample disturbance associated with the extraction of soil samples from ground. dynamic cone penetrometer (dcp) instrument is simple and portable. it is one of the in situ penetration test methods widely used in site investigation for estimating the strength and density of soils (sanglerat, 1972). the principle of dcp test is based on dynamic resistance offered by soil to deformation caused by dynamic penetrometer (braja, 1985). its application mostly limited to pavement overlay design. due to this, extensive attempts have been made by different researchers to find the empirical relationship between dcp reading and california bearing ratio (cbr) (scala, 1956; van vuuren, 1969; kleyn, 1975; livney, 1987; amini, 2003, etc.). their results suggests that cbr can be predicted satisfactorily from dcp values. however, as the results of previous works showed, the relationship between different engineering parameters with dcp is highly material dependent. regarding correlation between dcp reading and bearing capacity of a soil, only few works have been carried out on limited types of soil (i.e., lateritic soil) and mainly on re-moulded soils at lab scale (sanglerat, 1972; cearns and mckenzie, 1988; ampadu, 2005; dzitse-awuku, 2008). ampadu & dzitse-awuku (2009) also contributed towards the search for a correlation by measuring the bearing capacity of a model ground in the laboratory and correlating it to the dcp test results. in all these mentioned works, the dcp test was conducted on re-moulded and re-compacted materials at optimum moisture contents. in ethiopia including the study area, it is common to place the foundation of simple structure on natural ground at depth less than 3 meter. so far no attempt has been made to correlate the in situ dcp result with the bearing capacity of natural ground (uncompacted and at natural moisture content). in addition, previously developed correlation by different researchers to predict bearing capacity of soil have limited application to different study area and are typically only reliable over the range of data from which they were derived. adopting those developed correlations without improvement can lead to misinterpretation of soil behaviors. this study, therefore, attempts to establish correlation between allowable bearing capacity of shallow foundation and field dynamic cone penetration (dcp) reading for the case of expansive soils of asella town. 2. materials and methods field dcp test and soil sampling were carried out in asella town on 15 test pit locations (figure 1) where expansive soils are identified visually. depth of sampling varies from 1.5 – 2.5 m as it is common on the study area to place the foundation at this depth. both disturbed soil (for index properties test) and undisturbed soil (for tri-axial compression test) samples were extracted from test pits. for index properties test, the bulk soil samples were first air dried for about 3 days to almost constant moisture content. all the tests (i.e. grain size distribution, liquid limit (by casagrande method), plastic limit, specific gravity, free swelling index, etc.) were conducted on representative sample following the astm standards. two methods were used to find the particle-size distribution of the soil samples: sieve analysis, for particle sizes larger than 0.075 mm (no. 200) in diameter; and hydrometer analysis for particlesizes smaller than 0.075 mm in diameter. sodium hexametaphosphate (napo3) was used as a dispersion agent. the dcp test was performed in the test pit after excavation to the desired depth. the test device used in this study consists of two 16 mm diameter rods. the lower rod contains anvil and replaceable 60° apex cone. the upper rod contains 8 kg slide hammer with 575 mm drop height. the cone diameter (20 mm) is made wider than rod diameter (16 mm) so that penetration resistance is provided by cone alone and not side friction of the rods. the penetration achieved by each blow was recorded and plotted to obtain the dynamic cone penetration index (d-value). d-value is the penetration produced by one drop of the sliding hammer and it is obtained as the gradient of the line of best fit of the graph of cumulative blow against penetration in mm (figure 2). kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 61 r² = 0.9968 y = 31.665x 20.118 0 200 400 600 800 1000 0 10 20 30 40 d e p th p f p e n e tr a ti o n ( m m ) σ blow figure 1: location map of the study area and test pits figure 2: typical cumulative blows-penetration curve from dcp test (test pit 4) in tri-axial compression tests, a cylindrical soil sample of standard size (diameter = 38 mm and height = 76 mm) was trimmed from undisturbed core sample and encased by a thin rubber membrane and placed inside a chamber. for conducting the test, the chamber is filled with water and the sample is subjected to a confining pressure of 150 and 300 kpa by application of pressure to the water in the chamber. axial (or deviator) stress is applied through a vertical loading ram. no drainage is permitted during the test and specimen is sheared in compression without drainage at constant rate of axial deformation (strain controlled) of 1 mm/min. from stress-strain curve of tri-axial test, the deviator stress at failure and confining pressure were used to plot mohr circle. from mohr circle un-drained cohesion, cu, (intercept) and internal angle of friction, ø, (slope) were deduced and used to calculate the bearing capacity. the typical stress-strain curve and the mohr circle for the determination of the shear strength parameters are shown in figure 3 and 4, respectively. 3. results and discussion 3.1. the characteristics of the soil samples the index properties of the fifteen samples tested in the laboratory are summarized in table 1, while figure 5 shows the grading curves of the soils. all of the studied soil samples are described as fine grained soil with materials finer than 0.075 mm and 0.002 mm are 73% 91% and 35-53%, respectively. figure 3: typical stress-strain curve at different confining stress (test pit 12) figure 4: mohr circle drawn from stress-strain curve (figure 3) for determining cohesion (intercept) and internal friction angle (slope of tangent line) 0 100 200 300 400 500 0 2 4 6 8 10 d e v ia to r st re ss ( k p a ) axial strain (%) 300 kpa 150 kpa kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 62 table 1: basic properties of the soils used in this study the specific gravity of most of the soil was found to be in the range of 2.67 to 2.83 which is typical range for black cotton expansive soils (murthy, 2007). the liquid limit (ll) and plastic limit (pl) range from 56% 70% and 23% 40%, respectively. the plasticity index (pi) range from 12 to 47%. most of the soils of the study area fall in high plasticity type, except the soil from test pit 3 which is low plasticity type. similarly, the free swelling index (si) values and natural moisture content (nmc) are relatively higher indicating the soils under investigation possess significant water adsorption and retention capacity and higher swelling-shrinkage potential. classification of the soils according to unified soil classification system (uscs) is shown in figure 6. the plot shows that except the soil from test pit 3 and 15, which are high plastic inorganic silt (mh), the soil samples are classified as high plastic inorganic clay (ch). the results of the tri-axial tests showed that for all of the tested soils, a clear maximum deviator stress occurred at axial strain less than 7% at which the failure defined. the shear strength parameters (i.e. underained cohesion (cu) and internal friction angles (ø)) of the soils that used for computing bearing capacity are summarized in table 2. as indicated in the table, the cu ranges between 45 and 197.8 kpa and ø value ranges between 3º and 21º. the cohesion value is relatively higher and friction angle is lower as expected for fine grained cohesive soils. figure 5. grain size distribution of the soils test pit no. depth (m) clay fraction (%) nmc (%) ll (%) pl (%) pi (%) si (%) ci 𝛾dry (kn/m3) 𝛾 (kn/m3) 1 1.5 37.1 48.8 64 33.3 30.7 130 0.5 12.9 17.95 2 2.5 52.5 47 64 26.8 37.2 105 0.46 12.2 17.65 3 2 28.2 42.5 61 39.4 21.6 62.5 0.74 13.1 17.9 4 1.5 50 44.6 70 29.3 40.7 107.5 0.62 12.5 17.6 5 2.5 48.5 43.3 68 31.7 36.3 82.5 0.68 12.6 17.9 6 2 47.8 41.6 64 28.3 35.7 102.5 0.63 12.5 17.6 7 1.5 58.5 35.3 80 33.3 46.7 132.5 0.98 12.4 17.4 8 1.5 47.4 37.9 56 23.4 32.6 112.5 0.71 12.8 17.65 9 2 49.7 37.3 58 26.8 31.2 125 0.66 12.5 17.65 10 2.5 48.3 35.4 66 28.6 37.9 135 0.82 12.7 17.9 11 2 43.4 40.5 60 31.4 28.6 117.5 1.03 12.8 17.85 12 1.5 49.5 40.1 70 24.4 45.6 115 0.66 12.8 17.85 13 1.5 46.7 37.8 63.5 31 32.5 122.5 0.91 13 17.9 14 1.5 47.4 39.3 67.5 31.7 35.8 97.5 0.79 12.7 17.6 15 2 34.3 37.5 58.5 33.3 25.2 85 0.84 12.3 17.7 kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 63 figure 6: classification of the soils according to uscs table 2: the shear strength parameter and computed ultimate bearing of the soils 3.2. correlation between bearing capacity and engineering parameters from consistency index (table 1), physical state of the soils of study areas is dominantly stiff. for stiff cohesive soils and soils that show peak value in stressstrain curve at strain about 5%, types of bearing capacity failures are mostly general shear failure. hence, the allowable bearing capacity (qall) of the soil is computed using terzaghi’s bearing capacity equation (given below) with a factor of safety of 3. qall = [cu nc (1+0.3b/l) +𝛄df nq (1+b/l) +1/2𝛄bn𝛾 (1-0.2b/l)] / 3 where nc, nq and n𝛾 are terzaghi’s bearing capacity factors, df is depth of footing, b and l are the width and length of footing, respectively and 𝛄 is the bulk unit weight. test pit no. depth (m) cu (kpa) ф u ( 0 ) qall (kn/m2) dcp d-value (mm/blow) dcp n-value (blow/100 mm) 1 1.5 98.75 3 267.5 43.6 2.29 2 2.5 94.15 3 266.95 52 1.54 3 2 181.93 10 696.94 20.67 4.84 4 1.5 197.77 4 533.16 31.66 3.16 5 2.5 58.53 21 643.97 29.52 3.39 6 2 152.45 4 421.56 35.87 2.79 7 1.5 57.42 11 269.22 41.97 2.38 8 1.5 86.33 10 345.0 37.88 2.64 9 2 72.43 13 387.91 36.62 2.73 10 2.5 120.41 3 333.59 38.2 2.62 11 2 101.6 15 568.34 31.72 3.15 12 1.5 65.9 17 468.15 32.25 3.1 13 1.5 56.5 19 449.33 32.98 3.03 14 1.5 110 10 429.15 33.7 2.97 15 2 45 19 403.78 38.54 2.59 liquid limit (%) p la st ic it y i n d e x ( % ) kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 64 qall = -6.485 pi + 662.3 r² = 0.2 0 100 200 300 400 500 600 700 800 0 10 20 30 40 50 q a ll (k p a ) pi (%) qall = -2.9531 ll + 635.3 r² = 0.02 0 100 200 300 400 500 600 700 800 40 50 60 70 80 90 q a ll (k p a ) ll (%) qall = 44.936 ci + 410.25 r² = 0.003 0 100 200 300 400 500 600 700 800 0.4 0.6 0.8 1 1.2 q a ll (k p a ) ci qall = 230.91 ℽdry 2483.1 r² = 0.21 0 100 200 300 400 500 600 700 800 12 12.5 13 q a ll (k p a ) ℽdry (kn/m 3) rectangular footing of 1.5 m wide and 4 m long, which is a common footing dimension in the study area, and depth of foundation at proposed pit depth were used for ultimate bearing capacity determination. the results are summarized in table 2. to visually evaluate the data for potential relationship, a simple linear regression analysis between allowable bearing capacity (dependent variable) and dcp n-value is carried out. for comparison, the correlations with other properties of soils are also included. the scatter plots are shown in figure 7 to 12. from the figures, it can be observed that qall has weak negative correlation with ll and pi and weak positive correlation with ci, bulk and dry unit weight. on the other hand, qall has relatively strong negative correlation with dcp d-value as indicated by the coefficient of determination (r2) of 0.89. the relatively strong correlation between qall and dcp d-value indicates the potential of dcp test in complementing the conventional geotechnical testing methods to determine the bearing capacity of shallow foundation. the model is able to explain over eighty nine percent of the variation in bearing capacity of soil. to examine the effect of width of footing on prediction of bearing capacity from dcp test results, bearing capacity for different width of footing have been calculated from terzaghi’s bearing capacity equation and correlated with dcp d-value (figure 12). the coefficient of correlation remained almost the same for different width of footing, suggesting the width of footing has less effect on the prediction of bearing capacity from dcp reading. figure 7: plot of allowable bearing capacity (qall) and plasticity index (pi) figure 8: plot of allowable bearing capacity (qall) and liquid limit (ll) figure 9: plot of allowable bearing capacity (qall) and consistency index (ci) figure 10. plot of allowable bearing capacity (qall) and dry unit weight (ℽdry) kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 65 qall = 283.31 ℽ 4583.7 r² = 0.2 0 100 200 300 400 500 600 700 800 17.2 17.4 17.6 17.8 18 q a ll (k p a ) ℽ (kn/m3) qall = 1185.3 21.4 d r² = 0.8973 0 100 200 300 400 500 600 700 800 10 20 30 40 50 q a ll (k p a ) d value (mm/blow) y = -21.388x + 1185.3 r² = 0.8973 y = -22.347x + 1239.2 r² = 0.8867 y = -23.299x + 1292.6 r² = 0.8759 0 100 200 300 400 500 600 700 800 900 10 20 30 40 50 q a ll (k p a ) d (mm/blow) 1.5 m 2 m 2.5 m figure 11: plot of allowable bearing capacity (qall) and bulk unit weight (ℽ) figure 12. plot of allowable bearing capacity (qall) and dcp reading (d-value) figure 13. plot of allowable bearing capacity (qall) and dcp reading (d-value) for different footing width 3.3. evaluation and validation of the developed equation the validity of the developed empirical correlation has been examined by calculating ultimate bearing capacity using developed equation and comparing it with the actual value (i.e. computed using terzaghi’s equation) and also with previous works. as indicated in table 3, the average variation of the predicted bearing capacity from actual bearing capacity is about ±11.7%. it indicates that bearing capacity of expansive soil of study area can be reliably predicted from the field dcp readings. the result of this study is compared with the work of ampadu (2005) for the relationship between qall and dcp n-value (figure 14). the dcp device and the type of soil (i.e. high plastic fine grained soil) used by ampadu (2005) are similar with the present work. it must however be noted that, the test conditions are different. in the present case the dcp test was conducted in field at natural moisture content and density, whereas ampadu (2005) conducted the test inmould on re-moulded and re-compacted soil at optimum moisture content. hence, the range of n-values and computed bearing capacity are relatively lower in the present study. it can however be noted that, irrespective of testing conditions, the correlation equation for both works have comparable gradients i.e., as the n-value increases, the bearing capacity of the soil increases nearly at similar rate. figure 14. comparison of the developed empirical correlation between dcp reading and bearing capacity with the work of ampadu (2005). this study qall = 167.31 n 49.8 ampadu (2006) qall = 164.03 n 471.8 0 500 1000 1500 2000 2500 3000 3500 0 5 10 15 20 q a ll (k p a ) n (blow/100 mm) kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 66 table 3. comparison of calculated and predicted allowable bearing capacity 4. conclusion there is better correlation between bearing capacity and in situ dcp reading than between bearing capacity and index properties. the width of footing has no effect on the empirical correlation equation between dcp reading and bearing capacity. based on the results of this research study, it can be conclude that bearing capacity of shallow foundation can be predicted reliably from field dcp reading. therefore, it can be considered as cost effective alternative for preliminary site investigation of simple structures. however, for soils outside of the study area and/or on different soil types, users are advised not to fully rely on the developed equation or it should be used with extreme caution. additional works need to be done by increasing sample number and for different footing shape so as to validate the established correlation over the wide range. acknowledgment the author wish to thank adama science and technology university, postgraduate program, and bule hora university for providing financial support to mr. kemal. reference amini, f. (2003). potential application of dynamic and static cone penetrometers in mississippi department of transportation pavement design and construction. final report, mississippi department of transportation, usa. ampadu, s.i.k. (2005). a correlation between the dynamic cone penetrometer and bearing capacity of a local soil formation. proceedings of the 16th international conference on soil mechanics and geotechnical engineering, 655-659. sample no. actual qall (kn/m 2) from terzaghi equation predicted qall (kn/m 2) variation % a a (a-a)*100/a 1 267.5 252.3 5.7 2 267.0 72.5 72.8 3 696.9 743.0 -6.6 4 533.2 507.8 4.8 5 644.0 553.6 14.0 6 421.6 417.7 0.9 7 269.2 287.1 -6.7 8 345.0 374.7 -8.6 9 387.9 401.6 -3.5 10 333.6 367.8 -10.3 11 568.3 506.5 10.9 12 468.2 495.2 -5.8 13 449.3 479.5 -6.7 14 429.2 464.1 -8.1 15 403.8 360.5 10.7 average + 11.7 kemal abdela & chemeda y.c. ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 67 ampadu, s.i.k. and dzitse-awuku, d. (2009). model tests for bearing capacity in a lateritic soil and implications for the use of the dynamic cone penetrometer. proceedings of the 17th international conference on soil mechanics and geotechnical engineering. bell, f.g. (1996). lime stabilisation of clay minerals and soils. eng. geol. 42, 223–237. bowles, j. e. (1993). foundation analysis and design, 4th edition, mcgraw-hill, inc., new york braja, m.d. (1985). principles of foundation engineering, pws publisher boston cearns, p.j. and mckenzie, a. (1988). application of dynamic cone penetrometer in east anglia, proc. of the symposium on penetration testing in the uk, thomas telford, london. dzitse-awuku, d. (2008). correlation between dynamic cone penetrometer and allowable bearing pressure of shallow foundation using model footing: thesis submitted to department of civil engineering, kwame nkrumah university of science and technology. kleyn, e.g. (1975). the use of the dynamic cone penetrometer (dcp), report no. 2/74 transvaal road dept, south africa. livney, m. (1987): validation of correlations between a number of penetration tests and in situ california bearing ratio tests, transportation research record 1219, transportation research board, washington d.c. murthy, v. (2007). geotechnical engineering, principles and practice of soil mechanics and foundation engineering. new york: marcel dekker, inc. sanglerat, g., 1972, the penetrometer and soil exploration-interpretation of penetrometer diagrams-theory and practice, elsevier scientific publishing company scala, a.j. (1956). simple methods of flexible pavement design using cone penetrometers, new zealand engineer, 11 (2), 3344. van vuuren, d.j. (1969). rapid determination of cbr with the portable dynamic cone penetrometer, the rhodesian engineer, paper no. 105. 8 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper the achievements and challenges of kaizen implementation: a case study on asela malt factory hailu beyecha*, habtamu beri school of mechanical, chemical and materials engineering, department of mechanical design and manufacturing engineering, adama science and technology university, p.o. box: 1888, adama, ethiopia * corresponding author, e-mail: beyechahailu@yahoo.com abstract this study was meant to determine the status of the implementation of kaizen in asela malt factory and account for the improvements and challenges thereof. the design of the study was quantitative research method wherein spss was used for analyzing data elicited using questionnaire. the study specifically assessed the effectiveness of the implementation of kaizen tools such as 5s, deming cycle, suggestion system, fishbone diagram and pareto analysis. it was found that the kaizen tools were implemented inconsistently. in addition the study revealed that there were some improvements with some variations. the study also made it evident that there were some challenges in the due process. thus, kaizen tools should be implemented continuously to identify the root causes of the problems, prioritize the problems according to their severity and thereby solve them step-by-step to further improve quality, productivity and profitability through design and innovation. keywords: kaizen, kaizen tools, innovation, quality, productivity. 1. introduction the word kaizen is derived from two japanese words “kai” which means change and “zen” which means for the better (palmer, 2001). thus, kaizen is simply mean "change for better" or it is also referred to as "continuous improvement". it is a philosophy that promotes small improvements made as a result of continuing effort through the involvement of everyone in the organization from the top management to the lower level employees (mile and amrik, 2000). kaizen strategy has been successfully implemented by the japanese industry after world war ii (imai, 1986). kaizen was initiated in response to problem faced by the japanese industry after the world war ii such as limited resources and difficulties to obtain raw material (mohd and fatimah, 2016). therefore, as a result of the limited resources, japanese companies started to look for mechanisms of improving their production processes by minimizing wastes and optimizing process efficiencies. the underlying principle of the kaizen strategy is the recognition that management must seek to satisfy the customer and serve customer needs if it is to stay in business and make a profit. improvements in such areas as quality, cost, and scheduling (meeting volume and delivery requirements) are essential. kaizen is a customer-driven strategy for continuous improvement (mile and amrik, 2000). initially kaizen initiatives were led by toyota motor company in their effort to become global leader in the automotive industry which tried to emphasize on incremental changes, low cost solution, employee empowerment and the development of organization that holds continuous improvement with emphasis on process improvement rather than the result (imai, 1986). http://www.ejssd.astu.edu/ mailto:beyechahailu@yahoo.com hailu beyecha, habtamu beri. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 9 literature shows that there are no standard techniques used for implementation of kaizen (jignesh et al., 2014). however, kaizen implementation uses various techniques known as “kaizen toolbox”. among these, the main toolbox includes: 5s, fishbone diagram, pareto diagram, deming cycle and suggestion system (kobayashi, 2005; osada, 1989; kobayashi, 2005; evans and lindsay, 1999; imai, 1986; mile and amrik, 2000; lillrank and kano, 1989; kaoru ishikawa, 1968). furthermore, kaizen was also implemented within different parts of the world in mechanical, biological and pharmaceutical industries (altamirano, 2013; ananthanarayanan, 2006; chitre, 2010; mallick et al., 2013; pentti, 2014; purdy et al., 2013) and mining industry (aziza et al., 2018). having recognized kaizen as a strategic tool, ethiopia has established the “ethiopian kaizen institute (eki)” in 2011, by council of ministers under the regulation no 256/2011 and since then started to implement kaizen in the majority of private and government owned companies. asela malt factory is among the companies which have implemented the kaizen philosophy starting from 2013. the objective of this study is to assess kaizen implementation with respect to kaizen toolbox namely: 5s, fishbone diagram, pareto analysis, deming cycle and suggestion system in asela malt factory. more specifically, the study aims to assess the improvements achieved and the challenges encountered in the factory after kaizen implementation. 2. material and methods in the study, a quantitative research method has been employed in order to explore the relationships between variables. both primary and secondary data were collected and used in the study. the primary data were collected through questionnaire and personal observation of the factory. the questionnaire includes closed and open ended questions that enable the respondents to address the issues with regard to kaizen tools and the improvements and challenges that encountered the factory. respondents were selected purposively among permanent employees of the factory based upon their experience, position and participation in kaizen implementation. the secondary data were obtained from factory reports, different literatures and previous research works such as journals, periodicals and articles. among kaizen implementer's of ethiopian companies, asela malt factory was selected as a case study since it began to implement the kaizen philosophy starting from 2013. asela malt factory was established with the aim of producing malt for domestic breweries in 1984 with a capacity of 100,000 quintals annually. currently, the factory has a capacity to produce and distribute 360,000 quintals of malt to domestic brewers annually. asela malt factory has 260 employees that include 256 permanent employees, one contract and three temporary employees. since permanent employees have got exposure to see changes coming in the factory from time to time, only permanent employees were considered for the study. sample size was determined by using simple random sampling method and according to the following slovin's formula: n = n 1 + n(e)2 (1) where, n = sample size, n = total population and e = sampling error at 85% level of confidence n = 256 1 + 256(0.15)2 = 38 (2) as a result, 50 questionnaires were distributed to the respondents and finally 42 questionnaires were filled and returned from the respondents. thus, the response shows that the data was reliable at 85% level of confidence. scientific package for social science (spss) and descriptive statistics tools such as frequency and percentage were used to analyze and present the data obtained from questionnaire. additionally, the data gathered by observations were discussed in the result and discussion section. 3. results and discussion 3.1. demographic characteristics of the respondents table 1 represents the demographic characteristics of the respondents. table 1a represents qualification of the respondents, table 1b represents position of the respondents in kaizen implementation, table 1c represents service duration of the respondents in the factory and finally table 1d represents service duration of the respondents in kaizen implementation respectively. hailu beyecha, habtamu beri. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 10 table 1: demographic characteristics of the respondents a. qualification frequency percentage 1. secondary school or below 2 5% 2. diploma or certificate 6 14% 3. bachelor degree 25 60% 4. master degree or above 9 21% b. position in kaizen implementation 1. kaizen team member 24 57% 2. kaizen team leader 11 26% 3. kaizen facilitator 7 17% c. service duration in factory 1. 3-5 years 8 19% 2. 6-10 years 13 31% 3. 12-16 years 5 12 % 4. 20-26 years 5 12 % 5. 29-35 years 11 26% d. service duration in kaizen implementation 1. 0-2 years 2 5% 2. 3-4 years 15 36% 3. 5-6 years 18 43% 4. 7-10 years 7 16% total 42 100% table 1a shows that 60%, 21% and 14% of the respondents are bachelor degree holders, master degree holders or above, and diploma or certificate holders respectively. only the remaining 5% of the respondents have attended secondary school. table 1b shows the position of the respondents serving in the kaizen implementation. the data shows that 57%, 26% and 17% of the respondents are serving as kaizen team member, kaizen team leader and kaizen facilitator respectively. the data also shows that almost all of the respondents had an involvement in kaizen implementation. table 1c shows the service duration of the respondents ranging from 3-35 years in the factory. the data shows only 19% of the respondents have the lowest service duration in the company which ranges from 3-5 years. the remaining 81% of the respondents have service duration above 6 years in the factory. table 1d also shows the service duration of the respondents in kaizen implementation. the data shows only 5% of the respondents have the lowest service year (i.e. below 2 years) and the remaining 95% of the respondents have service duration greater than 3 years in kaizen implementation. the respondents with greater than 7 years of service duration in kaizen implementation have the experience of kaizen implementation before kaizen was implemented in the factory. 3.2. assessment of kaizen tools implementation in the factory table 2 represents the assessment of kaizen toolbox (i.e. 5s, deming cycle, suggestion system, fishbone diagram and pareto diagram) implementation in the factory. the assessment indicates the mean and standard deviation of the kaizen tools by using descriptive statistics of spss. hailu beyecha, habtamu beri. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 11 table 2: assessment of kaizen tools implementation in the factory table 2 shows that 5s is the most frequently implemented kaizen tool in the factory with some inconsistency as compared to the other tools. the data also shows that deming cycle is also implemented at the second level even if few respondents reflected that it is not properly implemented yet in the factory. in case of suggestion system, fishbone diagram and pareto diagram; some respondents had indicated that the tools were not implemented yet in the factory. but, the majority of the respondents had indicated that the tools were occasionally and frequently implemented in the factory. furthermore, some respondents had stated that deming cycle, suggestion system, fishbone diagram and pareto diagram were rarely and very rarely implemented in factory. however, the study shows that suggestion system was occasionally implemented in the factory. but according to womack et al. (2007), good suggestion system encourages effective communication between the top management and the shop floor level employees. it also encourages the employees to contribute their improvement ideas based on the experience they have gained throughout their daily working life. in addition, the kaizen tools enabled the japanese companies to improve customer satisfaction, improve productivity index, achieve world-class standard, increase employee job satisfaction and improve company revenue was the japanese suggestion system chen and tjosvold (2006) cited in (mohd and fatimah, 2016). in addition, some respondents suggested that additional toolbox such as just-in-time (jit) and total productive maintenance (tpm) were implemented in the factory. from the personal observation, it was observed that kaizen toolbox is inconsistently implemented in the factory. especially the implementation of deming cycle, suggestion system, fishbone diagram and pareto diagram were not observed at the time the researchers visited the factory. but, some workers reflected that they may use the tools some times and they may leave using the tools at the other time as they wanted personally. figure 1: average mean and standard deviation of kaizen toolbox descriptive statistics assessment on kaizen toolbox implementation mean std. deviation average mean std. deviation 5s sort 3.55 .739 3.75 0.790 set in order 3.83 .696 shine 3.95 .846 standardize 3.68 .756 sustain 3.74 .912 deming cycle plan 3.37 .925 3.50 0.832 do 3.57 .712 check 3.46 .745 act 3.61 .946 suggestion system kaizen board 3.33 1.248 3.12 1.158 checklist 2.90 1.068 fishbone diagram 2.91 1.522 2.91 1.522 pareto diagram 3.00 1.518 3.00 1.518 0 0.5 1 1.5 2 2.5 3 3.5 4 mean std. deviation hailu beyecha, habtamu beri. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 12 figure 1 shows the average mean and standard deviation of kaizen toolbox implementation in the factory. from the graph, it is possible to understand the existence of kaizen toolbox in the factory with some variations. 3.3. assessment of the improvements achieved in the factory table 3 represents the assessment of the improvements achieved in the factory after kaizen implementation. the assessment indicates the mean and standard deviation of the improvements calculated by using descriptive statistics of spss. the result in table 3 shows that majority of the respondents agreed that all the improvements were achieved in the factory. but, few respondents disagreed with the achievement of product quality improvement in the factory. furthermore, some respondents added that the following additional improvements were achieved after kaizen implementation in the factory. they are: reduction of costs, improvement of employee initiation to do jobs, improvement of modification works through innovation and improvement of profit to some extent with variation. in addition, it has been observed that the improvements achieved were not continued in the same fashion consistently. it also has been observed that the initiation of the management and many employees had declined throughout the implementation period of kaizen principles. teece, (2007) suggests that if companies need to improve their competitiveness, they need to apply continuous improvement or kaizen concept as one of the strategic tool in their organization. the benefits of kaizen implementation are to achieve improvements related with costs, quality, flexibility (bessant et al., 1994) and also productivity (choi et al., 1997). furthermore, the main contributing factor to the successful implementation of kaizen is top management’s commitment in having a clear corporate strategy, policies and goals that can stimulate kaizen culture in the organization (imai, 1986 and puvansvaran et al., 2010). according to the study conducted by garcia-sabater and marin-garcia (2011) management involvement, clear objective setting and measurement, active workers involvement, existence of crossfunctional teams, and clear organization structure are among the factors contributing to the success of kaizen implementation. additionally according to (bateman, 2003), a kaizen champion who has a good personal understanding in conducting kaizen, and a high personal desire and commitment to lead the continuous improvement activities can become a critical change agent in an organization. according to this scholar, this is one of contributing factors toward successful kaizen implementation. effective communication and management skills are also crucial factors for the kaizen champion (nonaka & takeuchi, 1995; pagell, 2004). therefore, this study revealed some benefits obtained after kaizen implementation with regard to quality, productivity and profitability in the factory. however, the study shows that the existence of some challenges after kaizen implementation have been observed in the factory. table 3: assessment of the improvements achieved in the factory after kaizen implementation descriptive statistics assessment on the achievements mean std. deviation management and employee relationship improvement 4.00 .937 employee and customer satisfaction 4.37 .662 convenient workplace creation 4.21 .682 resource utilization improvement 4.21 .750 space utilization improvement 4.05 .623 product defects/wastes reduction 4.00 .632 product quality improvement 3.95 .731 productivity improvement 4.07 .712 hailu beyecha, habtamu beri. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 13 3.4. assessment of the challenges encountered in the factory table 4 represents the assessment of the challenges encountered in the factory after kaizen implementation. the assessment indicates the mean and standard deviation of the challenges calculated by using descriptive statistics of spss. table 4: assessment of the challenges encountered in the factory after kaizen implementation descriptive statistics assessment on the challenges mean std. deviation lack of commitment to implement kaizen continuously 2.83 1.124 lack of responsible body for kaizen implementation 2.71 1.230 employee resistance towards continuous improvement 2.24 .969 lack of every employee involvement 2.74 1.178 high budget utilization for kaizen implementation 2.21 .963 lack of continuous training on kaizen implementation 3.20 1.159 complexity of paperwork after kaizen implementation 2.98 1.214 the result of table 4 shows that majority of the respondents disagreed that the above challenges were encountered in the factory. but, some respondents agreed with the existence of lack of commitment to implement kaizen continuously, lack of continuous training on kaizen implementation and complexity of paperwork after kaizen implementation. in addition, some respondents added additional challenges such as inability to reduce costs as needed, inconsistency in employee motivation through award, decline of employee morale through time and lack of crossfunctional team spirit for proper design and innovation. moreover, the challenges include: lack of regular participation of top management, need of all employees to be motivated through award, unnecessary motion within the factory, lack of on-job training for technicians, and inconsistency in the usage of kaizen toolbox. thus, it has been observed that since there was inconsistently in kaizen toolbox implementation, the challenges are expected to be persistent. 4. conclusion this study aimed at assessing the implementation of kaizen tools in asela malt factory in terms of 5s, deming cycle, suggestion system, fishbone diagram and pareto analysis. based on the findings of the study, it can be concluded that 5s is the most effectively implemented tool. similarly, the deming cycle is also implemented at the second level with some variations of concept among the respondents. however, the remaining tools, viz. suggestion system, fishbone diagram and pareto analysis are not properly implemented in the factory yet. it can also be concluded that despite the gap in implementing the kaizen toolbox in the factory, the study revealed that there is improvement in quality, productivity and profitability to some extent with variation. the study also made it evident that there were some challenges in the process of implementing of kaizen. the study also revealed that the commitment of the top management is the key factor in implementation kaizen. similarly, involving active workers and the existence of cross-functional teams can play a major role in effectively implementing kaizen. hence, to have a successful kaizen implementation, asela malt factory shall make sure that its top management should show utmost commitment besides putting in place a practical kaizen strategy and policy. finally, the researchers have forwarded their suggestions. accordingly, asela malt factory should properly implement kaizen tools in order to (1) identify the root causes of the problems by using fishbone diagram, (2) prioritize the problems according to their severity by using pareto diagram, (3) solve the problems step-by-step through proper design and innovation by using 5s, deming cycle, jit and tpm; and (4) communicate the solutions by using suggestion system to further improve quality, productivity and profitability of the factory. acknowledgement the authors would like to thank oromia agricultural cooperative federation and more specifically asela malt factory for their concern to support the accomplishment of this study by providing realistic and constructive information. hailu beyecha, habtamu beri. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 14 reference altamirano, r.j., (2013). aplicación de la metodología japonesa de calidad 5s para optimizar las operaciones en el laboratorio de mecánica de patio de la universidad de las fuerzas armadas – espe. universidad de las fuerzas armadas – espe, angolquí, ecuador. seifullina, a., ahmet, e., nadeem, s. p., garza-reyes, j. a., kumar, v. 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(2007). explicating dynamic capabilities: the nature and micro-foundations of (sustainable) enterprise performance. strategic management journal, 28(11), 1319 – 1350. womack, j., jones, d., & roos, d., (2007). the machine that changed the world published. new york: simon & schuster. 15 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper after effect of pump supply disruption niguss haregot hatsey school of mechanical and industrial engineering, mekelle university, mekelle, ethiopia * corresponding author, e-mail: nhpg23@gmail.com abstract the aim of this study is to investigate on the after effect of pump supply disruption in ground water irrigation in northern ethiopia. a survey is conducted in 16 sample drilled wells (dws) to reveal the losses because of supply delay. failure is inevitable and the failure of a submersible pump, critical equipment in irrigation infrastructure, is considerably high according to the survey. moreover, the downtime delay is the aggregation of purchasing order process delay, transportation delay and replacement/installation delay. discrete time probability distribution function is used to estimate the economic loss of the aftereffect by determining the cost, production volume and profit of the irrigation business using triangular probability distribution functions. the downtime is analyzed under the discrete time of 1 week downtime, 2 weeks downtime, 3 weeks downtime, and greater than 3 weeks downtime horizon. finally, the study ascertains that downtime in ground water irrigation results in sizable economic losses like yield loss, total vegetables/crops loss, and opportunity cost. when the downtime duration extends, the loss upturns radically. for instance, if the downtime duration extends from 1 week to 3 weeks, the expected monetary loss might increase in 10 folds. keywords: supply delay, submersible pump, downtime, economic loss. 1. introduction in ethiopia, where there is untapped potential water resource, water-centered economy is getting high attention (melesse et al., 2014). these days, the frequent drought and failure to access surface water forces to drill deep water wells (calow et al., 2010). to lift huge amount of water from deep wells, there is no as good as submersible pumps (gomez & nortes, 2012; takacs, 2018). despite the mechanical damage which is negligible, motor burn is a critical problem of electrical submersible pumps. according to the users and experts in the study area, submersible motor burns due to electric fluctuation and improper utilization. the study in raya valley by tadesse et al. (2015) indicates that sizable water wells cease function because of pump failure. more than the failure loss, the long downtime due to pump supply delay brings much more loss. while irrigation farming is susceptible to lack of water, the water supply downs for long period due to supply delay. delay is a function of time and time delay or aftereffect is a real process phenomenon (richard, 2003). in engineering, aftereffect is researched commonly in construction, control and communication, and supply chain (richard, 2003; arditi & pattanakitchamroon, 2006; sipahi & delice, 2008). delay in supply chain is delivery delay or deviation of lead time from the time defined both by supplier and client (blackhurst, 2018). transportation, inventory, information, and decision making are sources of delay (sipahi & delice, 2008). the delay times which commonly called the three delays (3d) are lead time delay, transportation delay, and decision making delay (sipahi & delice, 2010). http://www.ejssd.astu.edu/ mailto:nhpg23@gmail.com niguss haregot hatsey ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 16 the consequence of delay is economic loss (sipahi & delice, 2008) whereas the loss amount may not equal and the delay duration matters. however, in most cases delay time is not constant and considering delay time as a constant in a dynamic system is not realistic. accordingly, researchers have developed stochastic models which consider the variable delay time (qiu et al., 2015). both the discrete and continuous stochastic techniques like that of different probability distribution functions, decision tree with probability, and simulation runs can be used to manage the decision making under uncertainty (newnan et al., 2004). this study aims at determining the economic loss of down time in irrigation farming due to pump supply uncertainty and to identify the delay times in the whole supply system. the paper is organized as follows. the next section briefs about the methods and materials like the data collection and analysis tools. in the result and discussion, the 3rd section, the delay probabilities and effect of the delay outcomes are presented. finally, the conclusion part is presented. 2. methods and materials the study conducted a survey method to investigate the system downtime aftereffect and an analytical method to analyze the probability of delay and the economic loss. data is collected from key actors and stakeholders such as household farmers, government bodies, technical experts, and suppliers through questionnaires, interviews, group discussions, and referring to recorded historical data. from the survey, pump failure, number of pumps used to date, cost and profit figures of the farm activities, and other related data are collected. the pump related data like pump cost, pump rewinding (maintenance) and supply issue are collected from the randomly selected farmers, technical persons and the suppliers. the survey is conducted in northern ethiopia specifically in raya azebo district, a place where it has potential ground water and in the contrast which has critical problem in relation with pump failure and supply delay. it is conducted in 16 randomly selected sample drilled wells (dws) in which each dw comprises 36 hectares and more than 50 house holder farmers. the cost, production volume, profit and other similar quantitative figures are estimated based on the information provided by those selected farmers. check list was provided and distributed to 16 farmers in which each farmer comes from the selected 16 dws. downtime delays are analyzed by discrete time delays; 1 week, 2 weeks, 3 weeks and greater than 3 weeks downtime. then, delay probability in these discrete probability outcomes are estimated based on experts’ judgment. the delay’s economic loss is also calculated by determining the expected value of cultivation costs, profits and production volumes per hectare and dw. though it is possible to use other distribution functions, triangular distribution function is used to estimate the expected value of the variables as the date collected fits with it. 3. results and discussion 3.1. delay analysis from the survey conducted in 16 dws, a total of 34 failed pumps incident are occurred. the downtime or the delay time, time taken to make functional the dw (until replace the failed pump by new one), of each pump is assessed. table 1 categorizes the failure incidents in the down time length. table 1: failure incidents category in the downtime length downtime length in weeks 1 2 3 4 8 52 no. of failure incidents 7 10 7 7 2 1 downtime is the delay duration from purchasing new pump until replacing the failed one by new and then makes functional the dw. here, there are two cases; the actual time taken to process the operation of each activities and the delay time like waiting in queue to process order, waiting for pump supply, waiting for transportation means, and so on. 𝐷𝑡 = ə + 𝜏 (1) where dt is downtime, ə is the actual time and τ is the delay time. in the other side, 𝐷𝑡 = 𝑂𝑡 + 𝑇𝑡 + 𝑅𝑡 (2) where ot is the order time to process the pump purchasing order, tt is the transportation time and rt is the pump replacement time. in each activity there is a delay (τ). thus, niguss haregot hatsey ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 17 𝐷𝑡 = 𝑂𝑡ə + 𝑂𝑡𝜏 + 𝑇𝑡ə + 𝑇𝑡𝜏 + 𝑅𝑡ə + 𝑅𝑡𝜏 (3) the order delays may come from; report failures lately, late decision, absence of officials from duty, wait in queue until processing, wait the arrival of orders in case of pump stock out, reject order in case of supply shortage, and information delay. similarly, transportation delay may come from unavailability of transportation from/to farmland, wait for rig machine and technicians, delay due to road damage, and transportation delay or unavailability to bring pumps from supplier warehouses. likewise, the delays in association with pump replacement are; absence of technicians from duty, wait to rig truck in case if it is failed, waiting in queue until preceding operations done, and information convey delay. the throughput time (in this case the downtime), which is the pump supply lead time plus the installation time to make functional the down system, is the summation of ə and τ. while ə is constant but τ is variable. in the differential equation for variable time function; 𝑓(𝑡) = 𝑑𝑡(𝑡) (4) 𝑓(𝐷𝑡) = ə + 𝑑𝑡 (𝜏) (5) where dt(t) is the delay variable time arise due to waiting in queue, transportation delay, information delay, decision making delay, natural and manmade disruption, and so on. thus, the total downtime function is; 𝑓(𝐷𝑡) = 𝑂𝑡ə + 𝑇𝑡ə + 𝑅𝑡ə + 𝑑𝑡 (𝑂𝑡𝜏 + 𝑇𝑡𝜏 + 𝑅𝑡𝜏) (6) otτ, ttτ and rtτ ≥ 0 (7) otə, ttə, and rtə are constant. from the survey conducted by interviewing the farmers, the time taken to process the activities in days is estimated as 2, 1 and 1 for otə, ttə, and rtə respectively. this means, if there was no delay, the total downtime to replace a failed incident is 4 days i.e. less than 1 week. whereas if we see the data in table 1 (a data collected by the researcher from the 16 dws), a dw can down until 52 weeks (1 year) and down more than 1 week in all incidents. this shows there is significant delay in the district. the delay function can be modeled by probability distribution functions using the survey data in table 1 as a fundamental input. if the 1 year delay is considered as a special incident, the likelihood of delay time varies from 1 week to 2 months ranges. probability distribution function is used as it is more realistic than a deterministic approach (sun, 2017). although continuous probability can enable to get high range solutions, taking few but high likelihood discrete probability outcomes is simple to compute the expected value. in engineering applications, which don’t necessarily need continuous out comes, such model is common (newnan et al., 2004). table 2 shows the delay outcomes and its occurrence probability. the probability of occurrence is estimated after asking the farmers in the 16 dws. the 4th outcome, greater than 3, is designed by assuming that all vegetables on the farm will be destroyed if they couldn’t get water for more than 3 weeks. table 2: delay outcomes and the probability of occurrence delay outcomes in wks 1 2 3 >3 probability of occurrence 0.2 0.3 0.2 0.3 3.2. the economic consequence of delay since plants are vulnerable to water deficiency, the loss amount increases radically while the downtime increases. the expected losses are: productivity minimization loss (pl), destroyed loss (dl), and opportunity loss (ol). pl is the yield minimization due to not getting enough water. dl is complete destroy of plants in farmland due to lack of water and it is equivalent with the total cost invested to cultivate the plants. likewise, ol is the amount of profit gone if the plants were harvested. thus, downtime cost (dt cost) is; 𝐷𝑡 𝑐𝑜𝑠𝑡 = 𝑃𝑙 + 𝐷𝑙 + 𝑂𝑙 (8) to determine the lost amount precisely, detail estimation of each variable is required. in this study, however, it is estimated based on the experienced farmer’s expertize judgment (being expert here is the year of experience in the farming activities). as shown in table 3, the lost percentile increases dramatically while downtime increases by few days. the percentile indicates the amount of loss from the total productivity. niguss haregot hatsey ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 18 table 3: basic assumptions of the lost percentile for the delay outcomes the next task is to drill down the irrigation business costs and profits to calculate the total lost. the farmers cultivate various vegetables and crop types three times per year. the basic vegetables and crops that have been cultivated in the area are; onion, tomato, watermelon, pepper, maize, and teff. from now on ward p1, p2, p3, p4, p5 and p6 represents to onion, tomato, watermelon, pepper, maize and teff, respectively. the detail of the costs that would incur to cultivate the vegetables in irrigation per hectare in one round is summarized as in table 4. table 4. cost of different products in one hectare to get the most likely cost based on the probability functions, triangular distribution is used. the weighted average indicates the density of the distribution. since the weight of p3-p6 is totaled to 0.3, the mean value of these three is taken as a one value of the triangle. 𝑀𝑒𝑎𝑛 𝑣𝑎𝑙𝑢𝑒 = 23500 + 24500 + 24400 4 = 24300 𝑇𝑅𝐼𝐴(24300,48000,38500) = 𝑇𝑅𝐼𝐴 (𝑎, 𝑏, 𝑐) the following is a probability density of the triangular distribution function (allen, 2006). 𝑓(𝑥) = 0 𝑖𝑓 𝑥 ≤ 𝑎 𝑜𝑟 𝑥 ≥ 𝑏 (9) 𝑓(𝑥) = 2(𝑥−𝑎) (𝑏−𝑎)(𝑐−𝑎) 𝑖𝑓 𝑎 < 𝑥 ≤ 𝑐 (10) 𝑓(𝑥) = 2(𝑏−𝑥) (𝑏−𝑎)(𝑏−𝑐) 𝑖𝑓 𝑐 < 𝑥 < 𝑏 (11) a mean of random variable of the probability density function is given by mean value (µ) = ∫ 𝑥𝑓(𝑥)𝑑𝑥 ∞ −∞ (12) µ = 0 + ∫ 𝑥𝑓(𝑥)𝑑𝑥 𝑐 𝑎 + ∫ 𝑥𝑓(𝑥)𝑑𝑥 𝑏 𝑐 (13) µ = 0 + ∫ 𝑥𝑓(𝑥)𝑑𝑥 38500 24300 + ∫ 𝑥𝑓(𝑥)𝑑𝑥 48000 38500 µ = 0 + ∫ 𝑥 2(𝑥 − 24300) (48000 − 24300)(38500 − 24300) 𝑑𝑥 38500 24300 + ∫ 𝑥 2(48000 − 𝑥) (48000 − 24300)(48000 − 38500) 𝑑𝑥 48000 38500 = 36,915.4 lost types and loss amount downtime duration (weeks ) 1 2 3 >3 productivity minimization in % 10 25 50 destroy/loss in % 100 opportunity lost in % 100 cost types in per hectare for one term cost of each product (ethiopian birr (etb) ) p1 p2 p3 p4 p5 p6 land rent 7500 7500 7500 7500 7500 7500 water consumption fee 1500 1500 1500 1500 1500 1500 land preparation 5000 5000 5000 5000 5000 5000 nursery/seed cost 10000 4000 1000 1000 500 500 labor cost for transplanting the nursery 4500 2000 0 2000 0 0 fertilizer 6000 6000 1500 3000 6000 6000 pesticide 3000 5000 2000 1000 800 400 labor cost of watering and pesticide works 2500 2500 2000 1500 1500 1500 labor cost for weeding and related works 8000 5000 3000 2000 2000 2000 total cost 48000 38500 23500 24500 24800 24400 weight (the ratio of each type) 0.4 0.3 0.1 0.05 0.1 0.05 niguss haregot hatsey ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 19 expected cost for one hectare in one round is, therefore, expected to etb 36,915.4. to calculate the profit, sales volume should get first. since the quantity getting from one hectare varies from time to time as well the sales price varies also, 5 different values are taken by asking the users. in table 5, q stands for quantity and pr for price. table 5. sales volume of the different outputs based on the data in 2017/18 calendar profit (ƿ) is the subtraction of the cost (c) from the sales volume (s). ƿ = s − c (14) hence, profit can be calculated easily from table 4 and 5 and it is compiled as in table 6. table 6. profit estimation one hr’s types of vegetables/crops p1 p2 p3 p4 p5 p6 sales volume (etb) 96000 91000 55000 99375 34000 50375 cost (etb) 48000 38500 23500 24500 24800 24400 profit (etb) 48000 52500 31500 74875 9200 25975 the mean is estimated based on the triangular probability distribution. tria (9200, 48000, 74875) = tria (a, b, c) the following is a probability density of the triangular distribution. a mean of random variable of the probability density function is given by; µ = 0 + ∫ 𝑥𝑓(𝑥)𝑑𝑥 54000 15200 + ∫ 𝑥𝑓(𝑥)𝑑𝑥 58500 54000 µ = 0 + ∫ 𝑥 2(𝑥 − 9200) (74875 − 9200)(48000 − 9200) 𝑑𝑥 48000 9200 + ∫ 𝑥 2(74875 − 𝑥) (74875 − 9200)(74875 − 48000) 𝑑𝑥 74875 48000 = 44,000 the expected net profit from one hr in one round is etb 44,000. it is assumed that the average hectares in one dw are 36. the number of hectares that require water (on hectares) or doesn’t require (off hectares) should be estimated to know the amount under risk. those which don’t need water are not only that of uncovered by crops but also it includes those which cover by plantation but no more need water. according to the data collected from the site, the ratio of on-hectares and off-hectares is 65% to 35% or it is around 22 by 14 hectares respectively. expected sales volume (es) per hectare is calculated from the expected cost and profit. µs = µc + µƿ (15) types of vegetables/crops p1 p2 p3 p4 p5 p6 quantity in quintal in hectare (hr) q1 200 200 160 100 60 40 q2 140 160 120 80 40 25 q3 80 100 80 60 35 15 q4 60 60 40 40 25 10 ave. 120 130 100 75 40 22.5 price/kilo (etb) pr1 14 12 8 20 10 18 pr2 10 10 7 15 9 17 pr3 6 4 4 10 8 14 pr4 2 2 3 8 7 13 ave. 8 7 5.5 13.25 8.5 15.5 sales volume (etb) 96000 91000 55000 99375 34000 34875 niguss haregot hatsey ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 20 µs = 36,915 + 44,000 = etb 80,915/hr this means in raya azebo, the case study site, from one hectare in one round revenue of etb 80,915 per hectare is expected. in the other side, it is said that; dt cost = pl + dl + ol (16) risk of 1 week down time is the pl which is 10% of the µs dt cost 1 week = 0.1 µs dt cost 1 week = 0.1 ∗ 80,915 = 8,091.5/hectar or 8,091.5 ∗ 22 = 178,013/dw this means if one pump is down for 1 week etb 178,013 will be lost in the dw areal coverage since production is lost as a result of the downtime. dt cost 2 wks = 0.25 ∗ 80,915 = 20,228.75/hr or 20,228.75 ∗ 22 = 445,032.5/dw dt cost 3 wks = 0.5 ∗ 80,915 = 40,457.5/hr or 40,457.5 ∗ 22 = 890,065/dw dt cost for more than 3 weeks is the summation of the dl and ol. while dl is the expected cost, opportunity cost is the expected profit. this means that dt cost for greater than 3 weeks is equivalent to the total expected sales volume. dt cost > 3 𝑤𝑘𝑠 = 𝐷𝑙 + 𝑂𝑙 = µ𝑠 dt cost > 3 𝑤𝑒𝑒𝑘 = (80,915)/ℎ𝑒𝑐𝑡𝑎𝑟𝑒 = 80,915 ∗ 22 = 1,780,130/ 𝐷𝑊 this implies if water supply system is down for more than 3 weeks, the farmers in one dw can lose a gross of etb 1,780,130. all in all, as down time interval increases the severity of the risk increases radically. the downtime lost for each down time interval is exhibited in figure 1. 3.2. total delay loss the last analysis is to integrate table 2 and figure 1. the probability of delay is estimated as depicted in table 2 and in figure 1 the expected loss in each outcome is estimated. based on this, the total expected delay loss cost (µτc) is the summation of the 4 outcomes’ expected cost (µc) multiplied by the outcomes’ probability of occurrence. this is modeled as below. µτc = µc of 1 wk ∗ p(τ 1 wk) + µc of 2 wks ∗ p(τ 2 wks) + µc of 3 wks ∗ p(τ 3 wks) + µc of > 3 𝑤𝑘𝑠 ∗ 𝑝(τ > 3 𝑤𝑘𝑠) µτc = 8091.5 ∗ 0.2 + 20228.75 ∗ 0.3 + 40457.5 ∗ 0.2 + 80195 ∗ 0.3 = etb 39,836.925 figure 1. downtime costs of various durations the total expected delay loss cost per hectare in the case study is etb 39,836.925. the total expected loss cost per dw is, total loss/dw = 39,836.925 ∗ 22 = etb 876,412.35 currently, the administrators have reported that per year 5 pumps are failed. if this number is taken to estimate the total loss in the district as a result of delay; yearly loss = loss dw ∗ number of dws = 876,412.35 ∗ 5 = 4.4 million thus it is estimated that, in raya azebo district, etb 4.4 million/year is lost due to supply delay. if this number is used to estimate the loss in nationwide, it could be very huge. if it is expected also that similar delay scenarios are happened in other developing countries, the model can use to estimate similar delay losses. 4. conclusion determining expected delay time using deterministic approach is dispensable method for variables which are not certainly known. to overcome such challenges, niguss haregot hatsey ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 21 probabilistic (stochastic) approach is a sound solution to make decision under uncertainty. discrete time probability outcomes are taken based on experts’ judgment to represent the possible expected delays. although continuous probability out comes can help to widen the solution range, taking few but high likelihood discrete probability outcomes based on experts’ judgment is representative and simple to compute the expected value and this is especially common in engineering applications which didn’t necessarily need continuous out comes. likewise, economic loss costs can be estimated in a better but manageable way using triangular distribution functions. in this study, the water supply system downtime of the irrigation farm in raya azebo district due to pump supply delay is investigated and it is found that the pump supply delay is lengthy and uncertain. the delay probability outcomes and the expected loss outcomes are integrated to compute the economic loss. accordingly, aftereffect of submersible pump supply in groundwater irrigation farming is measured in economic loss. the economic loss in one irrigation district, in raya azebo, northern ethiopia, is estimated to be etb 4 million annually. when taking this figure to compute the aftereffect loss in nationwide it could be a terrible number. this shows how delay disruption affects the business in developing countries. this research can serve as an input to the policy makers, researchers, practitioners, and consultancies who engage in irrigation farming in developing countries. reference allen, t.t. 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(2018). electrical submersible pumps manual, design, operations, and maintenance (2nd ed.). gulf professional publishing. 7 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper production of biogas from calabash waste mixed in selected ratios with sheep and donkey dungs. tewabech temesgen mekonnen , moges admasie mengstie, fasika kebede shewareged department of industrial chemistry, college of science, bahir dar university, bahir dar, ethiopia article info abstract article history: received 13 april 2022 received in revised form 20 august 2022 accepted 30 september 2022 anaerobic digestion process is one of the non-thermal technologies of energy recovery to meet the ever-growing energy demand of rural areas in developing countries, particularly ethiopia, in a green way. the aim of the present study was to investigate the effectiveness and performance characteristics of anaerobic digestion of calabash waste mixed in selected ratios with donkey and sheep dung for biogas production. production of biogas from calabash waste, mixed with donkey and sheep dung in ratios 1:1, 2:1, 3:1, and 4:1 by mass, was investigated in a 45 l plastic container using a retention period of 20 days and within the mesophilic temperature range. the average biogas yield was significantly (p≤ 0.05) influenced by the different mixing ratios of calabash waste with dung. the composition of gas generated from each ratio ranged (from 67.41-63.81)% ch4, (33.00-26.01)%, co2, (1.06-0.40)% co, (3.000.07)% h2o, (0.06-0.02)% nh4,(0.90-0.05)% n, (0.72-0.02)% h, (0.98-0.09) % o2, and (0.006-0.001) % h2s. the average biogas yield was 13.5, 11.6, 10.7, and 7.8l respectively for 1:1, 2:1, 3:1, and 4:1 mixing ratios when calabash waste was mixed with sheep dung. on mixing calabash waste with donkey dung, the average biogas yield increased to 16.2, 15.5, 12.6, and 9.8l respectively for 1:1, 2:1, 3:1, and 4:1 mixing ratios. the results show that mixing both dungs with calabash waste in a ratio of 1:1 by mass-produced the highest biogas volumes, and higher in donkey dung. the reason behind this is that higher mixing ratios meant a higher quantity of waste in the mixture which also implied increased lignin content, and this made digestion activities more difficult for the microbes. reduction in digestion activities of the methanogen bacteria resulted in lower biogas yield. the result of the present study has shown that anaerobic digestion from calabash waste, mixed with donkey and sheep dung in ratios 1:1, 2:1, 3:1, and 4:1 by mass can form a renewable energy that is comfortable and environmentally friendly. this energy production process is found to be an easy way of replacing fossil fuels. keywords: biogas, calabash waste, retention time, anaerobic digestion 1. introduction energy is one of the prerequisites for the growth of agriculture and industry (rai and da silva, 2017). the energy requirements are met mainly through commercial energy sources such as oil and natural gas (fossil fuel). fossil fuels are exhausting and their toll on humanity is high in terms of environmental degradation, the spread of disease, and climate change/global corresponding author, e-mail: tewabech.temesgen@bdu.edu.et https://doi.org/10.20372/ejssdastu:v10.i1.2023.458 warming via greenhouse gas (ghg) emissions (shane and gheewala, 2017). currently, the prices of these commercial energy sources have increased gradually and there is a continuous depletion of these scarce resources (arrhenius et al., 2019). the global quest for renewable and sustainable energy generation has been http://www.ejssd.astu.edu/ tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 8 incessantly increasing over the years as the sequence of the increasing world population (arrhenius et al., 2019) the world’s demand for energy grows rapidly, and therefore, it is time to look for alternative and renewable energy resources to replace the rapidly depleting supply of fossil fuels. many countries have realized that biogas is a source of energy that is highly needed for sustainability transition (bahr et al., 2014; nevzorova and kutcherov, 2019). however, the total production volume of biogas in developing countries is still relatively low (gemechu, 2020). such slow development raises a fundamental question—what are the current barriers hindering the wider uptake of biogas as a source of energy. to this end, there is a need for the integration of cleaner production technologies in solving the world's numerous environmental challenges most especially the issues in energy generation and utilization by using locally available organic waste and dung (kumar et al., 2014; faizalet al., 2018). biogas is one of the good and promising sources of alternate energy(sawyerr et al., 2019). this energy can be harnessed successfully to meet the existing as well as future needs of rural areas. biogas is a renewable energy source produced from organic material (agricultural waste, dung, municipal waste, vegetable waste, sewage, green waste, or food waste), which is broken down with the help of bacteria in an anaerobic (oxygen-free) environment (ighravwe et al., 2018). it has been used as a viable alternative fuel for a variety of domestic purposes in different countries, notably china and india (muzenda, 2014). depending on the nature of the organic compound, the complexity of the process will increase and the step of anaerobic digestion will also change to some extent (mulat and horn, 2018). in this process, several steps are involved and several microorganisms are responsible for these steps of anaerobic digestion (miah et al., 2016). the flow chart (steps) of aerobic digestion is depicted in figure 1 (ngan et al., 2020). 2. materials and methods 2.1. materials in this experiment, fresh calabash wastes, donkey and sheep dung, plastic containers, and water were used as feedstocks. in this work, a floating dome-type collector, that is, a movable gas holder biogas digester was used. a gas collector, mixer and grinder (bx-1002) were also employed. necessary chemicals such as ash and others were added to regulate the ph change. 2.2. methods 2.2.1. collection & preparation of raw materials fresh calabash wastes were collected from around gordema farms, 3km from bahir dar city, ethiopia. sticks, stones, leaves, and other foreign matter were then hand-picked from the mass of collected waste, after which the waste was chopped, pounded and stirred to break into smaller particles to ensure the consistency of the mix. fresh donkey and sheep dung were collected from the livestock farms at zezelema farms, 5km from bahir dar city. stones and sticks were removed from the dung, which was finally thoroughly stirred. i) chemical & physicochemical analysis of blends the blends of calabash waste and donkey and sheep dung of each ratio were dried and ground into smaller particles to increase the surface area of the blends. these ground blends were brought to the soil research centre at bahr dar for further analysis. the analysis of the blends was performed at the department of national soil research centre in bahir dar following standard procedures (ryan et al., 2001; tuzen et al., 2008). kjeldahl digestion and distillation apparatuses were used to determine the nitrogen (n) content of the blends (hicks et al. 2022). the carbon content of the blends was measured with the help of the method found by wang and geng (2015). a flame photometer was used to determine the content of sodium (na) and potassium (k) in the blends (banerjee and prasad, 2020). the contents of copper (cu) and zinc (zn) in the blend were analysed using atomic absorption spectrophotometer (siraj and kitte, 2013). the content of phosphorus (p) in the blend was analysed by spectrophotometer, the method described by adelowo and oladeji (2016). the content of ammonium (nh4) in the blends was determined by the method described by gates et al., (2005). this instrumental analysis was performed in triplicates, and the average result was taken. moisture content, ash content, lignin content, total solid and volatile solid of the blends of calabash waste with donkey and sheep dungs of each ratio were determined by the methods described by sluiter et al., (2008); pieces et al., (2014); fagerstedt et al., (2015). tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 9 figure 1. flow chart / steps of an aerobic digestion 2.2.2. biogas production the effect of calabash waste mixed with the donkey and sheep dung in the ratios 1:1, 2:1, 3:1, and 4:1 for biogas production was investigated in a 45l plastic container, using a 20-day retention period. two kilograms (2kg) of calabash waste and 2kg of dung were measured and mixed thoroughly in a 45l plastic container. the mixture was further mixed with 20l of water and 0.4kg of firewood ash. the slurry was then stirred with a wooden stick to mix the contents thoroughly. the ph of the slurry was then checked with litmus paper and found to be around 8. a 25 l gas collector, with the open end directed into the biodigester containing the slurry and having a gas outlet at the top was gently pushed into the digester to remove any atmospheric gas found in the bio-digester. a hissing sound was heard showing that air is being pumped out which eventually faded. at this point, the gas outlet was closed from where the digestion process for biogas generation started. the ph of the slurry was recorded daily by using litmus paper. biogas production was measured daily on a volume basis by water displacement. the ambient temperatures on site were continually measured using a maximum and minimum thermometer and recorded throughout the retention period. biogas samples were obtained on day 6 and day 20 of the retention period and the generated biogas was collected using a gas collector and analysed for methane content using a gas detector, gas chromatographmass spectrometer (gc-ms) (model: gc-7820a, agilent technologies; detector-5977emsd, usa) column: db-1701. instrumental analysis was performed three times and average results were taken. the same procedure was repeated for ratios 2:1 (2kg of waste, 1 kg of dung, and 0.2kg of ash with 15l of water added), 3:1 (3kg of waste, 1kg of dung, and 0.1kg of ash with 30l of water added) and 4:1 (3.5kg of waste, 1.5kg of dungs, and 0.2kg of ash with 25l water added). each digestion process was run in triplicates to see the reproducibility of the results. 2.2.3. statistical analysis statistical data were analysed with spss version 23. multi variant (one-way anova with blocking) statistical package was used in analysing the average biogas measurement for their significance within the different mixing ratios and between calabash waste and dung. tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 10 3. results and discussion 3.1. chemical and physicochemical analysis the results of the chemical analysis of blends in each ratio such as %k, %p, %nh4, %na, %zn, %cu, %lignin, %moisture content, and % ash are shown in table 1. the results are consistent with other results reported elsewhere (adelekan and bamgboye, 2009; yaru et al., 2014 andtsapekos et al., 2017). the values of moisture content in the blends ranged from (86.86188.451) %; this optimum moisture content is favourable for the enhancement of biogas yield (sorathia et al., 2012). the values of lignin content in the blends ranged from (0.941-1.923) %; these lower values are favourable for enhancing the methane yield and hydrolysis rate significantly (piątek et al., 2021; zhang et al., 2021). the values of ash content in the blends ranged from (2.341-1.792) %; these values are desirable for biogas production(jijai et al., 2017). the contents of macronutrients (%k, %p, %na, and % nh4) and micronutrients (% zn, % cu) in the blends are desirable and good for further application as bio fertilizer after biogas production(siswanti et al., 2019; audu et al., 2020). table 1: chemical analysis of blends in each ratio blends ratio %k %p %nh4 %na %zn %cu lignin, (%) moisture content,% %ash calabash waste (cw) with donkey dung (dd) 1:1 0.231± 0.040 0.085± 0.041 0.951± 0.081 0.023± 0.014 0.003± 0.002 0.005± 0.004 0.941± 0.501 88.340± 0.980 2.051± 0.090 2:1 0.512± 0.051 0.065± 0.032 0.842± 0.150 0.045± 0.023 0.005± 0.003 0.004± 0.002 1.732± 0.603 88.30± 0.871 1.930 ± 0.160 3:1 0.410± 0.030 0.042± 0.014 0.634± 0.109 0.051± 0.016 0.004± 0.002 0.002± 0.001 1.568± 0.510 87.41± 0.851 1.981± 0.510 4:1 0.321± 0.021 0.036± 0.015 0.581± 0.091 0.073± 0.034 0.002± 0.001 0.003± 0.001 1.653± 0.440 86.92± 0.691 1.891± 0.409 calabash waste (cw) with sheep dung (sd) 1:1 0.234± 0.060 0.071± 0.031 0.741± 0.150 0.054± 0.032 0.002± 0.001 0.006± 0.002 1.521± 0.075 87.340± 0.670 1.851± 0.093 2:1 0.124± 0.045 0.231± 0.061 0.651± 0.095 0.065± 0.014 0.003± 0.001 0.005± 0.003 1.731± 0.150 86.861± 0.643 1.792± 0.130 3:1 0.091± 0.012 0.141± 0.051 0.561± 0.034 0.076± 0.032 0.001± 0.001 0.002± 0.001 1.851± 0.460 88.451± 0.741 2.341± 0.230 4:1 0.312± 0.042 0.341± 0.043 0.751± 0.084 0.077± 0.014 0.002± 0.001 0.001± 0.001 1.923± 0.270 87.921± 0.571 1.941± 0.461 table 2: physicochemical analysis of blends in each ratio blends ratio total solid (%) volatile solid (%) carbon content (%) nitrogen content (%) carbon to nitrogen ratio (c:n) calabash waste with donkey dung 1:1 4.84±1.20 22.60±0.90 27.12±1.01 1.24 ±0.71 27:1±1.40 2:1 6.84±1.20 40.32±0.81 24.31±0.81 1.42±0.91 24:1±0.89 3:1 9.30±0.51 60.12±1.02 24.48±0.52 1.04±0.61 24:1±0.85 4:1 10.23±0.70 75.31±0.41 26.53±0.72 1.61±1.02 26:1±0.71 calabash waste with sheep dung 1:1 3.76 ±0.53 25.21±0.56 26.65±0.42 1.34±0.61 26:1±0.69 2:1 5.94±0.92 39.34±0.46 25.41±0.64 1.24±0.95 25:1±0.67 3:1 8.45±0.74 82.32±0.58 24.54±0.59 1.41±0.68 24:1±0.87 4:1 11.03±0.85 59.57±0.63 26.54±0.72 1.23±0.69 26:1±1.04 tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 11 the result of the physicochemical analysis of the blends in each ratio is shown in table 2. this result agrees with guarino et al., (2016) and choi et al., (2020). the carbon-nitrogen (c/n) ratio of the blends was obtained from the physicochemical analysis. one to one (1:1) ratio of waste mixed with donkey dung had the highest c/n ratio of 27.12, followed by a 1:1 ratio of waste with sheep dung (26.65), 4:1 ratio of waste with sheep dung (26.57), 2:1 ratio of waste with sheep dung (25.41), 3:1 ratio of waste with sheep dung (24.54), 3:1 ratio of waste with donkey dung (24.48), and 2:1 ratio of waste with donkey dung (24.31). generally, all the selected ratios had the optimum c/n ratio, and this result is found to be good for biogas production (sreekrishnan et al., 2004; guarino et al., 2016). having an optimum c/n ratio has been suggested for the anaerobic digestion process because a very high or low c/n ratio may inactivate microbes in the anaerobic digestion processes, which reduces the activity of methane-producing bacteria and activate other side products forming bacteria (baum et al., 2002; jos et al., 2018). the result of the blends in all digesters was high in %vs but low in % ts. this high volatile matter content was anticipated because of the organic nature of the material used. the contents of volatile matter in biomass materials are usually high due to the organic nature of the biomass (sajeena et al., 2013; syaichurrozi and sumardiono, 2014; orhorhoro et al., 2017). generally, the results of total solid, volatile solid and carbon to nitrogen ratio of calabash waste with donkey dung and calabash waste with sheep dung in each ratio were different, and these different may be due to the content of dung & the conditions of anaerobic digestion process (mukumba et al.,2016; nagy et al.,2019). 3.2. composition of biogas from mixture of calabash waste with donkey and sheep dung the samples of the biogas generated from all the digesters were collected and analysed using a gas detector (nwagbo et al., 1991; liu et al., 2018). table 3 and table 4 show the result of the composition of biogas from the mixture of calabash waste with donkey dung and calabash waste with sheep dung respectively. the results of this study are in a comparable range with the findings reported in some studies elsewhere (carcelon and clark, 2002; koch et al., 2015). the 1:1 ratio of waste mixture with donkey dung had the highest ch4 content (67.41±0.98 %) and its co2 value is (27.23±0.81 %), followed by the 3:1 ratio of waste with donkey dung (66.91±0.68 %) with co2 value of (26.01±0.56 %), 1:1 ratio of waste with sheep dung (66.90 ±1.23 %) with co2value of (29.23±0.76 %), 2:1 ratio of waste with donkey dung (66.50±1.05) with co2 value of (28.09 ±0.67 %), 4:1 ratio of waste with donkey dung (65.61±0.49 %) with co2 value of (31.06±0.39 %), 2:1 ratio of waste with sheep dung (65.510±1.09 %) with co2 value of (32.00±0.86 % ), 3:1 ratio of waste with sheep dung (65.12±0.98 %) with co2 value of (31.03±0.59 %), and ch4 content of 4:1 ratio of waste with sheep dung (63.81±0.69 %) with co2 value of (33.00±0.79 %). trace levels of co, h2o, nh4, n, h, o2, and h2s are also presented in this result. t he r e a s o n f o r t h e l o w v a l u e o f m e t h a n e c o n t e n t i s p r o b a b l y b e c a u s e s i g n i f i c a n t q u a n t i t i e s o f c a r b o n d i o x i d e a n d o t h e r n o n c o m b u s t i b l e ga s s e s w e r e p r o d u c e d i n t h e a n a e r o b i c d i ge s t i o n o f c a l a b a s h w a s t e w i t h s h e e p d u n g ( c a r c e l o n a n d c l a r k , 2 0 0 2 ; p i ą t e k e t a l . , 2 0 2 1 ) . table 3. composition of biogas from mixture of calabash waste with donkey dung components concentration (by volume) in % 1:1 2:1 3:1 4:1 methane(ch4) 67.41±0.98 66.50±1.05 66.91±0.68 65.61±0.49 carbon dioxide (co2) 27.23±0.81 28.09 ±0.67 26.01±0.56 31.06±0.39 carbon monoxide (co) 0.70 ±0.65 0.90±0.18 0.40±0.91 0.60±0.46 water (h2 o ) 2.90 ±0.74 3.00 ±0.73 1.51±0.56 2.06±0.29 ammonia (nh4) 0.04±0.64 0.03±0.23 0.05±0.47 0.02±0.01 nitrogen (n) 0.05±0.73 0.08±0.51 0.90±0.08 0.31±0.38 hydrogen (h) 0.09 ±0.19 0.02±0.01 0.08 ±0.06 0.05±0.01 oxygen (o2) 0.81±0.04 0.91±0.03 0.61±0.05 0.09 ±0.02 hydrogen sulphide (h2s) 0.003±0.01 0.005±0.01 0.004±0.02 0.002±0.01 tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 12 table 4: composition of biogas from mixture of calabash waste with sheep dung component concentration(by volume) in% 1:1 2:1 3:1 4:1 methane (ch4) 66.90 ±1.23 65.510±1.09 65.12±0.98 63.81±0.69 carbon dioxide (co2) 29.23±0.76 32.00±0.86 31.03±0.59 33.00±0.79 carbon monoxide (co) 0.81±0.52 0.60 ±0.05 1.06 ±0.60 0.90±0.32 water (h2o) 0.90 ±0.04 0.08±0.05 0.90 ±0.04 0.07 ±0.02 ammonia (nh4) 0.05±0.03 0.04±0.02 0.06±0.30 0.03 ±0.01 nitrogen (n) 0.70±0.04 0.65±0.05 0.51±0.31 0.49±0.23 hydrogen (h) 0.09±0.12 0.08 ±0.09 0.72±0.28 0.05±0.14 oxygen (o2) 0.91±0.50 0.98±0.07 0.40±0.01 0.75±0.06 hydrogen-sulphid(h2s) 0.003±0.002 0.006±0.001 0.002±0.001 0.004±0.001 3.3. average biogas measurement from the mixture of calabash waste and dung the results of the average biogas measurements of each ratio are found to be comparable with the values in some studies reported elsewhere (adelekan and bamgboye, 2009; mukumba et al., 2016; alkhamis et al., 2021). the average biogas measurement decreases by a 1:1 to 4:1 ratio in all ratios, as illustrated in table 5. statistical analysis also shows that the average biogas yield was significantly (p≤ 0.05) influenced by the different mixing ratios of calabash waste and dung, as shown in table 6, figure 2 and figure 3. this means that the 1:1 ratio has a greater biogas yield than the 2:1 ratio, a 2:1 ratio greater biogas yield than the 3:1 ratio, and a 3:1 ratio greater biogas yield than the 4:1 ratio. in 1:1, the ratio gets higher biogas yield and the 4:1 ratio gets the least biogas; thus, when the amount of waste increases and the dung decreases, the yield of biogas diminishes. the reason behind this is that higher mixing ratios meant a higher quantity of waste in the mixture, which also implied increased lignin content and this made digestion activities more difficult for the microbes(mulat and horn, 2018). reduction in digestion activities of the methanogen bacteria resulted in lower biogas yield. furthermore, with time, the waste rapidly ferments and becomes more acidic. acidic environment is not well tolerated by anaerobic bacteria; therefore, their rapid multiplication will be severely curtailed at the higher mixing ratios which contained more waste in the mixture (abubakar et al., 2004;chellapandi, 2004;adelekan and bamgboye, 2009). in general, the average biogas yield of waste mixed with donkey dung is higher than the average waste mixed with sheep dung in every successive ratio. this low value is due to the fact that the body of sheep dung is solid as compared with donkey dung and less amount of fermentative bacteria is found in sheep dung. this makes it not easily fermented in the microbes (adelekan and bamgboye, 2009; alkhamis et al., 2021). 3.4. effect of variation of ph on/ during the digestion period the microorganisms are sensitive to ph because each group survives at different ranges. from figure 4 and figure 5, we can see that the ph of waste with donkey dung and sheep dung in each ratio was 8 (day one), but the ph reduces as the process goes on and as the bacteria produces fatty acids. here, methanogens bacteria that utilize fatty acids is a slow reaction, compared to other bacteria, so it is the rate-limiting step in the reaction (al mamun and torii, 2014; jos et al., 2018). furthermore, waste with sheep dung in each ratio ph decreases highly and the reaction is fast, which means that the hydrolysis and acidogenesis reaction is fast as the organism utilizes the waste more speedily than waste with donkey dung (figure 4). thus, the yield of biogas is decreased compared to the mixture of waste with donkey dung (mukumba et al., 2016; alkhamis et al., 2021). thus, the result of the ph measurements of each ratio is compatible with jos et al. (2018) and victor et al., (2018). the anaerobic fermentation study was investigated within the daily ambient temperature range of 25.3°c to 37.9°c for all the digesters. the lowest temperature reading of 25.3°c was obtained on the 9th day while the tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 13 highest temperature of 37.9°c was recorded on the 16th day of digestion process and the other records fluctuated within this range. therefore, at constant, mesophilic temperature ranges the methane-producing bacteria convenient for the fermentation process and would give better gas yield (getahun et al., 2014; liu et al., 2018). table 5: summary of average biogas measurement from mixtures of calabash waste and dung table 6: effect of different mixing ratios of waste and dung on average biogas yield test of between-subject effect source dependent variable type iii sum of squares df mean square f sig. corrected model biogas yield for wwdd 76.613a 3 25.538 1532.267 .000 biogas yield for wwsd 52.283b 3 17.428 275.171 .000 intercept biogas yield for wwdd 2197.813 1 2197.813 131868.800 .000 biogas yield for wwsd 1423.541 1 1423.541 22476.961 .000 ratio for wwdd and wwsd biogas yield for wwdd 76.613 3 25.538 1532.267 .000 biogas yield for wwsd 52.282 3 17.427 275.171 .000 error biogas yield for wwdd .133 8 .017 biogas yield for wwsd .507 8 .063 total biogas yield for wwdd 2274.560 12 biogas yield for wwsd 1476.330 12 corrected total biogas yield for wwdd 76.747 11 biogas yield for wwsd 52.789 11 r squared = .998 (adjusted r squared = .998); b. r squared = .990 (adjusted r squared = .987) where wwdd = waste with donkey dung and wwsd =waste with sheep dung figure 2. effect of different mixing ratios of waste and donkey dung on average biogas yield. component average biogas volume of each ratio(l) 1:1 2:1 3:1 4:1 waste with donkey dung 16.2±1.08 15.5 ± 0.86 12.6±0.76 9.8±0.64 waste with sheep dung 13.5± 0.94 11.6 ±0.65 10.7±0.62 7.8± 0.57 tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 14 figure 3. effect of different mixing ratios of waste and sheep dung on average biogas yield figure 4. variation of ph during the digestion period of waste with donkey dung in each ratio figure 5. variation of ph during the digestion period of waste with sheep dung in each ratio 2 3 4 5 6 7 8 9 0 5 10 15 20 25 ph of 1 to 1 ratio ph of 2 to 1 ratio ph of 3 to 1 ratio ph of 4 to1 ratio retention time (days) ph 3 4 5 6 7 8 9 0 5 10 15 20 25 ph of 1 to 1 ratio ph of 2 to 1 ratio ph of 3 to 1 ratio ph of 4 to1 ratio ph retention time (days) tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 15 3.5. effects of digestion time on daily average biogas yield in this study, the measurement of the daily average biogas yield waste with donkey dung and sheep dung in all digester biogas production started on the 6th day and reached its apex on the 20th day as shown in figure 6 and figure 7, and the results agree with adelekan & bamgboye, (2009) and alkhamis et al., (2021). this length of the days to get biogas on the onset of the digestion period because it takes time for the substrate to decompose and generate biogas; the production of the biogas is directly related to the specific growth of methanogenic bacteria (sagagi et al., 2009; ngan et al., 2020). as shown in figure 6, the average biogas measurement waste with donkey dung in all ratios started on day 6 by producing a minimum amount in a little difference of each ratio. thereafter, the amount of the average biogas yield increased day-to-day in all ratios. on day 13, the maximum amount of the average biogas yield was obtained that 1:1 (2.5 l), 2:1 (2.5 l), 3:1 (2.25 l), and 4:1 (2 l). after day 14, the production of biogas started to reduce day-to-day in all digesters. this finding indicates that all substrates in the digesters have been consumed, and biogas production was almost zero (narayani and priya, 2012; nagy et al., 2019). as shown in figure 7, average biogas measurements for waste containing all ratios of sheep manure started on day 6, with the smallest amount produced with a slight difference from each ratio. thereafter, the amount of average biogas yield increased day-to-day in all ratios. on day 15, the maximum amount of average biogas yield with the ratio of 3:1 (1.7 l), and 4:1 (1.4 l) was obtained. on day 16, the maximum amount of average biogas yield with the ratio of 1:1 (2 l) and 2:1 (1.5 l).was obtained after day 15 (ratio 3:1 and 4:1) and day 16 (ratio 1:1 and 2:1), the production of biogas started to reduce day-to-day in all digesters. this finding indicates that all substrates in the digesters have been consumed, and biogas production was almost zero (sawyerr et al., 2019). figure 6.measurement of daily average biogas yield with digestion time of calabash waste & donkey dung mixture figure 7. measurement of daily average biogas yield with digestion time of calabash waste & sheep dung mixture 0 0.5 1 1.5 2 2.5 3 0 5 10 15 20 25 volume of biogas measured (l) 1to 1 ratio volume of biogas measured (l) 2 to 1 ratio volume of biogas measured (l) 3 to 1 ratio retention time (days) b io g a s (l ) 0 0.5 1 1.5 2 2.5 0 5 10 15 20 25 volume of biogas measured (l) 1to 1 ratio volume of biogas measured (l) 2 to 1 ratio retention time (days) b io g a s (l ) tewabech temesgen et al. ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 16 3.6. biogas combustibility & volume measurement the combustibility of the biogas generated in all digester ratios was tested with a match placed at the mouth of the gas outlet. the measurement of the volume of biogas generated by the water displacement method was done on the 6th-20th days of the start of digestion. the measurement was run in triplicate to see the reproducibility of the result, and a combustibility test was done for each measurement (itodo et al., 1995; mukumba et al., 2016). the gas produced was seen to burn with a blue flame on the 6th day since the onset of digestion. the gas generated from waste mixed with donkey dung had a relatively stronger blue flame than waste mixed with sheep dung (alkhamis et al., 2021). 4. conclusion the result of this research on the comparison of biogas productivity of calabash waste mixed in selected ratios with sheep and donkey dung has shown that flammable biogas can be produced from each ratio through anaerobic digestion. from this, it was observed that the strength of produced flammable biogas was different for each ratio. slurries containing calabash waste with donkey dung produced more average biogas than the corresponding mixing ratios of calabash waste with sheep dung. of all ratios, the mixture of 1:1 mass produced the highest biogas, while the mixture of 4:1 mass produced the least biogas in both dungs. thus, a 1:1 ratio means the amount of calabash waste with dung (both donkey and sheep dung) equal amounts and enhances the anaerobic fermentation process. this enhancement was because dungs contain fermentative bacteria and free lignin materials. on the other hand, 4:1 means that the amount of waste has higher than the number of dung with proportion to this waste has bulky and accumulates some lignin relatively dung this leads retardation of the anaerobic fermentation process and decreases the number of biogas yields. recommendation this study recommends mixing sheep and donkey dungs with calabash waste in the ratio of 1:1 by mass intended for biogas production from methane-generating systems., calabash waste mixed with donkey dung in a ratio of 1:1 by mass is found to be a better alternative for the enhancement of biogas yield. data availability all the necessary information required for replication of this work and/or conducting secondary analysis is included within the article. conflicts of interest the authors declare that they have no conflicts of interest. acknowledgments the authors would thank to the department of chemistry, industrial chemistry, and biology for the 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carbon emissions calculation from municipal solid waste and the influencing factors analysis in china. j. clean. prod., 104: 177-184. yaru, s., k. adewole and i. adegun (2014). comparative study of biogas from cattle dung and mixt ure of cattle dung with plantain peels. nig. j. technol. res., 8(2): 44-49. zhang, q., j. zhang, s. zhao, p. song, y. chen, p. liu, c. mao and x. li (2021). enhanced biogas production by ligninolytic strain enterobacter hormaechei ka3 for anaerobic digestion of corn straw. energies 14(11): 2990. 39 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9(1), 2022 journal home page: www.ejssd.astu.edu.et astu research paper engineering geological investigation of jimma town for engineering practice mekdes habtamu1, tola garo2, yadeta c. chemeda2 1college of natural and computational science, bonga university, bonga, ethiopia 2department of applied geology, school of applied sciences, adama science and technology university, p.o. box: 1888, adama, ethiopia article info abstract article history: received 15 october 2021 received in revised form 31 january 2022 accepted 17 march 2022 jimma is one of the major and densely populated towns in ethiopia. it is located 348.5 km southwest of addis ababa. as in many towns of ethiopia, very little is known about the soil and rock engineering properties and subsurface conditions of the town. therefore, the present research work aimed to evaluate the geological and engineering geological condition of the town. detailed field survey, in-situ strength test, sampling, geological mapping, and laboratory testing of samples were conducted. a total of 12 disturbed soil samples were collected from 12 test pits, which were dug manually up to 3 m depth. geological and engineering geological maps were prepared at a scale of 1:25,000. laboratory results revealed that the natural moisture content, liquid limit, plastic limit, plasticity index, specific gravity, and free swell of the soils range from 41.97–62.45%, 66–101%, 31–62%, 19–59%, 2.36–2.75, and 33–130% respectively. the area is dominantly covered by high plastic silt and clay soil type. basalt, ignimbrite and tuff are the lithological rock units identified in the study area, which are classified into three major engineering geological subunits: very high strength, high strength, and very low strength (soft) rock units. flooding and high swelling potential of the soils are the main geological hazards that require due consideration in the study area. keywords: jimma town engineering geological engineering practice geological swelling potential 1. introduction jimma town is one of the densely populated and rapidly growing towns in the country. the town is mainly known for its immense coffee origin and production. with high population growth, the town is currently expanding in all directions, and numerous civil engineering structures such as single to multi-story buildings, roads, bridges, and industrial parks are under construction. however, the unplanned expansion of towns has exposed people and economic assets to the risk of natural disasters. in this aspect, jimma town has to adjust its planning strategies regarding its territorial expansion and growing construction sector. thus, there corresponding author, e-mail: tolagaro6@gmail..com https://doi.org/10.20372/ejssdastu:v9.i1.2022.400 is a need for engineering geological investigation of the rocks and soils of the town. engineering geological investigation is a precondition for the economic design and safety of civil engineering structures (bell, 2007; kitata adugna and yosef yirga, 2020). it involves understanding the index and engineering properties of the rocks and soils (kelly, 2016; l’heureux and lunne, 2019) to identify geotechnical problems so that proper remedial measures can be provided (wazoh and mallo, 2021). in geotechnical engineering, soils and rocks are considered problematic if they are not suitable for construction without the adoption of some types of stabilization http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i1.2022.400 mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 40 measures (adejumo et al., 2012; wazoh and mallo, 2021). expansive and collapsible soils are among the most common problematic soils in geotechnical engineering (houston and zhang, 2021). problematic rocks are those that are characterized by low bearing capacity, high potential for sliding and differential settlement, dissolution, karstification, and subsidence (vondráčková and bellanová, 2015). expansive soils, in particular, are partially saturated plastic soil that exhibits high volume change when its environmental conditions are altered from dry to wet (elshater et al., 2019). according to kalantari (2012), seasonal moisture changes, percentage of fine materials, dry density, permeability, and presence of vegetation trees are responsible for the volumetric changes associated with expansive soils. moreover, the degree of expansion depends on whether the soil mass contains active clay minerals such as montmorillonite (sabtan, 2005). numerous reports of expansive soil problems and their related damages to engineering structures such as the lifting of buildings, damage to basements, and building settlement have been documented in different countries (rao et al., 2004; calik and sadoglu, 2014; odunfa et al., 2018). this damage to engineering structures by expansive soils is estimated to be in billions of dollars per year (sachim et al., 2014). in ethiopia, expansive soils cover an appreciable part with an estimated aerial coverage of 24.7 million acres (lai, 1971; nebro, 2002). it is widely spread in the central part of ethiopia following the major trunk roads like addis-ambo, addis-woliso, addis-debrebirhan, addis-gohatsion, and addis-modjo and also areas like mekele, jimma, and gambella (mesfun et al., 2019). likewise expansive soils, problematic rocks can also pose several engineering geological problems to the structures founded on them. for example, sliding rock mass (i.e. rock slope instabilities) can cause significant damage to any infrastructure along its paths (pantelidis, 2009). significant variation in strength and/or bearing capacity of rocks due to geological contacts and discontinuities can lead to differential settlement of structures (shaunik and singh, 2020; galindo et al., 2020), etc. hence, to prevent damage to civil engineering infrastructures due to such problematic soils and rocks, engineering geological investigation is very crucial. in jimma town, however, despite recent rapid urbanization and construction activity, only a handful of studies have been conducted to avail engineering geological condition of the town. for example, sorsa et al. (2020) and jibril (2014) studied the geotechnical properties of soils of the town. nevertheless, engineering geological characterization of rocks, geohazard and groundwater condition of the town, and their influence on construction have not been studied in the above-mentioned works. mengesha et al. (1996) also mapped the regional geology of the jimma area, and yet, this work has forwarded very limited engineering geological information as the study was conducted at a small scale. therefore, this research work aimed to assess and evaluate the engineering geological condition of jimma town to produce geological and a multipurpose engineering geological map that can be used for future land use planning, design, construction, and maintenance of engineering structures. 2. methodology 2.1. description of the study area the study area, jimma town, is located in the southwestern part of oromia national regional state (figure 1). it is situated at 348.5 km from the capital, addis ababa, and covers an area of 50.52 square km. it lies between 846007 to 855007 m n latitude and 258036 to 267036 m e longitude. elevation within the town boundary ranges from 1720 m.a.s.l. at the kitto airfield to 2010 m.a.s.l. around jiren mountain. climatically it is classified as ‘‘weina dega’’ with a mean daily temperature of 19.8°c and monthly rainfall ranging between 1.8 mm in february to 335 mm in june (ema, 1981; uidp, 2013) 2.2. desk study a detailed literature review on available geological and geotechnical data of the study area was carried out to gain a preliminary understanding of the engineering geological condition of the study area. these preexisting data include topographic maps, aerial photography, satellite imagery, digital elevation model (dem), hydrogeological and geological maps. moreover, a detailed review of the subject matter related to the research topic was also carried out. later conceptual framework and general methodology were mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 41 figure 1: the location map of the study area. developed from the knowledge acquired through literature review and fieldwork was planned accordingly. 2.3. field survey and sampling geological mapping, discontinuity surveying, in-situ strength testing, and soil and rock sampling were carried out in this stage. geological mapping was carried out along systematically selected traverse lines. descriptions of geological materials were carried out in the field in terms of color, orientation, degree of weathering, thickness, etc. the degree of weathering was determined by considering the response of rocks to blow by geological hammer following the guidelines forwarded by isrm (1978). discontinuity surveying was also carried out along with geological mapping to obtain parameters of discontinuity such as orientation, infill material, spacing, aperture, etc. delineation of potential areas that are highly susceptible to geological hazards such as flooding was also carried out. ucs of intact rock is the most important property of intact rocks that can be used in the design of civil engineering structures. it can be determined either directly at the field via schmidt hammer or in the laboratory from representative samples (hoek and bray, 1981). according to barton and bandis (1990), strength tests in the laboratory depend on the size and how the sample is held. schmidt hammer strength test in the field is simple, suitable, and reliable due to practically unlimited sample sizes. based on this assumption, this study determined ucs of intact rocks of the study area directly at the field using schmidt hammer. the guideline for the schmidt hammer strength test was given by isrm (1978) and astm (2018) in which the former recommended the use of l-schmidt hammer type while the latter did not specify the hammer type. in this regard, aydin (2009) suggested that n-type hammers are less sensitive to surface irregularities and are preferred for field surveys whereas l-type hammers are more sensitive to lower ranges and give a better result for weak, weathered, and porous rocks. because of the surface irregularities and nature of rocks of the study area, this study has employed an n-type silver schmidt hammer using the guidelines of astm c805 (2018). accordingly, this test was conducted at 8 different locations (figure 2), and numerous readings were taken mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 42 at each location. the tests were conducted by gradually pushing the hammer perpendicular to the test surface and then corresponding hammer rebound values of rocks were recorded. ten readings were taken at each test section with no two test locations closer together than 25 mm. a representative rebound value was obtained by discarding the rebound values that differ from the average of 10 readings by more than 7 units and then by determining the average values of the remaining readings. finally, the representative rebound values were converted into ucs of rocks using the empirical equation suggested by barton and choubey (1977). a total of twelve test pits (figure 2) were excavated to a depth of 3 m, and disturbed soil samples were collected. the sampling locations were initially identified based on the distribution of soil in the town. immediately after sampling, the soil samples were kept in plastic to preserve their natural moisture content. 2.4. laboratory test to identify and evaluate problematic soils such as expansive soils, different laboratory tests can be conducted. for example, tests such as moisture content, specific gravity, grain size analysis, atterberg limits, shrinkage limits, mineralogical tests such as x-ray diffraction, swell tests, and suction measurement are recommended by several researchers such as asuri and keshavamurthy (2016), elshater et al. (2019), wazoh and mallo (2021), etc. for identification of soil type and presence of expansive soil. in light of this concept, tests such as moisture content, specific gravity, free swell, grain size analysis, and atterberg limits were conducted in this study to achieve the aims of the study. all of these tests were conducted at the geotechnical laboratory of jimma university. the tests were conducted following astm standards as presented in table 1. figure 2: the location of test pits and schmidt hammer test mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 43 table 1: type of test and standard employed for each type of soil laboratory tests no type of test number of samples standard employed 1 moisture content 12 astm d 2216 (1998) 2 specific gravity 10 astm d 854 (1998) 3 grain-size analysis 12 astm d 422 (1998) 4 atterberg limit 12 astm d 4318 (1998) 5 free swell 7 astm d 4546 (1998) 3. results and discussion 3.1. geology of the study area the study area is covered by quaternary soil deposits and different types of extrusive igneous rocks such as basalt, ignimbrite, and tuff units. 3.1.1. quaternary deposit quaternary soil deposits of the study area include alluvial and residual soils and cover a majority of the study area (figure 3). the alluvial deposit is mainly exposed following the central part of the study area and extends north-south following the stream valleys. it is fine-grained, grey, and reddish in color. residual soils of the study area are derived from in-situ weathering of basaltic and ignimbrite rocks. this deposit relatively covers a large area along gently sloped topography. the thickness of this unit is greater than 3 m as it is observed along the road and stream cut exposure. 3.1.2. basalt this rock unit is mainly exposed forming cliffs toward the northern and north-eastern part of the study area (figure 3). it is fine-grained, light gray, and has a vesicular texture. it is slightly weathered and dominantly affected by horizontal and vertical joints. some of the joints and vesicles of this rock are also filled with secondary materials such as quartz. 3.1.3. ignimbrite this rock unit is mainly exposed along the eastern and north-western parts of the study area. it is slightly to moderately weathered and fractured and recognized by its dark grey color. in the study area, this rock is currently being used as masonry stone to build different types of civil engineering structures due to its workability. 3.1.4. tuff tuff rocks unit, which is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption, is exposed in the eastern part of the study area (figure 3). it is characterized by white color and a finegrained texture. due to the poor compaction and cementation of volcanic ash, this rock unit is weak and soft. in some areas, it is also found intercalated with basaltic rock. 3.2. geological structures geological structures affect the stability of civil engineering structures constructed on discontinuous rock masses. the main geological structures observed in the study area are joints. it is observed in all rock units. most of the joints are vertically dipping with variable spacing, aperture, infill material, persistence, wall weathering, and roughness. the analysis of orientation data of joints using dips software showed that the rocks of the study area are dominantly affected by two major joint sets oriented in ne and nw, and one minor joint set oriented in n-s direction (figure 4). in addition, one regional fault is identified in the ne part of the study area from satellite imagery and regional geological map. this fault cuts through basaltic rock and is oriented relatively in the nw direction (figure 3). 3.3. geological hazard geological hazards can pose severe constraints on development. however, if the area prone to hazards is identified in advance, it will be very easy for the local government units to establish controlling or mitigating measures to lessen the effect of such hazards. therefore, establishing land-use zoning considering geo-hazards is very important to protect people and their properties. 3.3.1. flood jimma town is surrounded by steeply sloped ridges or hilly topographic features which is why it is frequently subjected to flooding during the rainy season. among 13 kebeles of jimma town, ginjo guduro kebele is located in a lowly elevated area and is directly affected by surface runoff from jiren mountain. according to tolera abdissa & fayera gudu (2019), mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 44 about 38.6% of the total area of this kebele is dominantly affected by the flood. in the past decade alone, flooding has destroyed several roads, bridges, and dwelling houses in different parts of the town. hence, due consideration is very important concerning flooding during the design of civil engineering structures in the town. figure 3: geological map (the scale is reduced from 1:25,000) and geological cross section (a to b). mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 45 figure 4: rose diagram of joints of the study area plotted using dips6.00 software. 3.3.2. earthquake earthquake is shaking of the ground due to rapid release of energy and can cause catastrophic damage to anything along its path. areas located along or close to tectonic plate boundaries are known to be highly susceptible to an earthquake. in this regard, jimma town is located outside the main active tectonic boundary in ethiopia, the main ethiopian rift (mer). moreover, according to the seismic hazard map of ethiopia produced by ebcs (1995), jimma is located in zone 1 (zone of minor damage). however, historical records have shown that the town has experienced ground shaking in the past by earthquakes that have originated from nearby areas. for example, the town has experienced ground vibration due to earthquakes that originated from hosanna and yirgalem area during 2010 and 2009 g.c., respectively. moreover, an earthquake can also occur outside main tectonic plate boundaries with active regional faulting. in this aspect, mengesha et al. (1996) have mapped some active regional normal faults in the vicinity of the study area. hence, these faults require due consideration when evaluating the seismicity of the study area. 3.4. index properties and classification of soils 3.4.1. moisture content the physical properties of most fines grained and particularly clayey soils are greatly affected by the water content. the natural moisture content of soils of the study area ranges from 41.97 to 62.45% (table 2). the results imply that the soils of the study area dominantly have relatively high water holding capacity as the fine fraction is the dominant grain size. hence, soils of the study area are expected to exhibit relatively higher volume change (swelling and shrinkage) associated with moisture content variation. moreover, the high moisture content of some soils of the study area, particularly tp3 is potentially attributed to high organic content. this is because organic composts with high organic carbon and micronutrient content impart high water holding capacity to the soil (ram and masto, 2014) leading to a direct relationship between the percentage of organic matter and water content (pradeep and vinu, 2015) 3.4.2. specific gravity specific gravity is an important parameter of soils as it is used for the determination of void ratio and particle size (arora, 2004). the specific gravity of the soils in the study area varies from 2.36 to 2.75 (table 2). pradeep and vinu (2015) stated that specific gravity non-linearly decreases with an increase in organic content as organic material is comparatively light in weight with respect to soil particles. as these light organic matters occupy a considerable portion of the unit volume of soil, highly organic soil possesses lesser specific gravity. the amount of lightweight organic matter present in compost amended organic soil yields low specific gravity values (puppala et al., 2007). hence, the lower specific gravity value for some soils of the study area, such as tp-3 could be due to the presence of organic matter. 3.4.3. grain size analysis grain size analysis is used to determine the amount of different types of grain size present in the soil. the analysis was done according to the standard astm d 422 (1998). for soil particles greater than 75 µm in diameter, sieve analysis was done, while hydrometer analysis was performed for particles less than 75 µm in diameter. the result shows that the predominant size of soil particles in the study area is fine-grained soils which have gravel content ranging from 0-0.98%, sand fraction 0.35-4.59%, silt fraction 24.05-55.91%, and clay 42.1671.36% (table 2). amagu et al. (2018) stated that the implication of a higher percentage of fines in an engineering material is that the finer soil particles can be easily eroded away by water thereby decreasing the bonding between soils and making compaction difficult. this implies that almost all the studied soils of the study mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 46 table 2: natural moisture content, specific gravity, and grain size analysis results sample no. depth (m) nmc (%) specific gravity grain size distribution gravel sand silt clay tp-1 3 44.79 2.63 0.13 1.20 38.03 60.51 tp-2 3 50.52 2.55 0.03 0.62 48.08 50.95 tp-3 3 62.45 2.36 0.00 3.16 40.15 56.69 tp-4 3 52.39 2.65 0.12 2.18 35.15 62.42 tp-5 3 52.08 2.61 0.98 0.35 37.34 57.20 tp-6 3 42.18 2.59 0.00 1.21 41.59 57.20 tp-7 3 48.61 2.62 0.12 1.64 50.69 47.55 tp-8 3 51.07 2.53 0.26 2.99 52.36 44.13 tp-9 3 44.69 2.74 0.00 1.93 55.91 42.16 tp-10 3 44.82 2.75 0.00 4.59 24.05 71.36 tp-11 3 44.25 0.00 2.32 30.00 67.60 tp-12 3 41.97 0.02 3.38 41.60 54.98 area are susceptible to erosion effect and hence, flooding as well. moreover, based on elshater et al. (2019) and wazoh and mallo (2021) high percentage of fines can also imply a high potential for expansiveness. 3.4.4. consistency limit and swelling potential the atterberg limits test results of the studied soils are summarized in table 3. the test results analysis showed that liquid limit, plastic limit, and plasticity index of soils in the study area range from 66%-101%, 31%-62%, and 19%-59%, respectively (table 3). based on the study conducted by azam et al. (2013), calik and sadoglu (2014) and christodoulia (2015), soil with a liquid limit above 54–83% are considered expansive with a greater tendency for compressibility and excessive settlement. all the liquid limit values of soils of the study area are either greater than or within the above range (table 3) which is potential proof for the expansiveness of soils of the study area. moreover, based on recent classification of soil forwarded by elshater et al. (2019), with exception of soils obtained from tp-2, tp-8, and tp-11 that are medium plastic, all the soils of the study area fall into high to very high expansive/or plasticity classes. this also implies a high degree of the expansiveness of soils of the study area. such high expansive potential makes the soils of the study area highly susceptible to differential settlement of the foundation (wazoh and mallo, 2021). with regard to the use of soils as sub-base and sub-grade material, adeyemi (2002), rao et al. (2004), etc. recommended that the plasticity index should be less than the upper limit of 25%. based on these studies, with exception of soils obtained from tp-2, tp-8, and tp-11 (table 3), all are unsuitable for sub-base and sub-grade foundation materials because they have a plasticity index >25%. 3.4.5. activity activity is first described by skempton (1953) and is a ratio of plasticity index of soil to the percent of clay size fraction in the soil. it is widely used to identify the type of clay mineral in the soil and estimate the swelling potential of soil. accordingly, skempton (1953) suggested that if the activity is less than 0.75 soil is inactive, 0.75–1.25 soil is normal, and greater than 1.25 soil is active. in the light of these concepts, the activity of the soils of the study area was computed and found to be in a range of 0.28–1.02 (table 3). the analysis of the results also showed that 50% of studied soils of the study area are classified as normal soil while the remaining were classified as inactive soils. 3.4.6. free swell free swell is used to determine the potential of a soil for expansiveness. accordingly, the free swell soils of the study area vary from 33–130% (table 3). soils with a free swell value less than 50% are considered nonexpansive, 50–100% are marginally expansive, and greater than 100% are expansive (bis is 1498: 1970(r2002)). based on this classification, soils that mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 47 table 3: atterberg limits, activity, and free swell of soils of the study area sample no. liquid limit (%) plastic limit (%) plasticity index (%) activity free swell (%) tp-1 66 31 35 0.57 130 tp-2 70 49 21 0.41 58 tp-3 92 43 49 0.86 43 tp-4 97 38 59 0.94 100 tp-5 101 53 48 0.83 63 tp-6 87 34 53 0.92 125 tp-7 82 54 28 0.58 33 tp-8 72 53 19 0.43 tp-9 74 42 43 1.02 tp-10 75 45 30 0.42 tp-11 81 62 19 0.28 tp-12 91 37 54 0.99 were obtained from test pits tp-1, tp-4, and tp-6 are classified as expansive soil. similarly, soils from test pit tp-2 and tp-5 are classified as marginally expansive while those from test pit tp-3 and tp-7 are classified as non-expansive. according to holtz and gibbs (1956) cited in bell (1983), soils with a free swell value as high as 100% can cause considerable damage to lightly loaded structures, and soils with a free swell value below 50% seldom exhibit appreciable volume change even under very light loadings. therefore, careful consideration is required concerning the design of different types of structures in the parts of the study area that are characterized by free swell as high as 100 or more. 3.4.7. engineering classification of soils a soil classification scheme provides a method of identifying soils in a particular group that would likely exhibit similar characteristics and is very important for the preliminary assessment of engineering properties of soils. it is also used to specify a certain soil type that is best suited for a given application. there are several classification schemes available and were devised for specific use. for example, the american association of state highway and transportation officials (aashto) developed one scheme that classifies soils according to their usefulness in roads and highways. in contrast, the unified soil classification system (uscs) was initially developed for airfield construction but was later modified for general use. in this study, both aashto and uscs were used to classify the soils of the study area. according to the aashto classification system, all soil samples obtained from the study area were classified under group a-7-6 category (table 4), and hence their suitability as sub-grade material is poor. concerning group index in this classification system, das (2012) suggested that the quality of performance of soil as a subgrade material is inversely proportional to the group index. moreover, arora (2004) forwarded that soils with group index 20 or greater show very poor sub-grade. in the light of these concepts, all soils of the study area have a group index greater than 30 indicating that they are very poor to be used as sub-grade material without treatment. similarly, based on uscs, soils obtained from tp1, tp-4, tp-6, and tp-12 were classified as inorganic clay of high plasticity (table 4 and figure 5). on the contrary, soils from the remaining test pits were classified as inorganic silt of high plasticity (table 4 and figure 5). according to alhassan et al. (2014), clay minerals that are present for the soils that fall in the region of high plasticity and compressibility in the plasticity chart are dominantly expansive clays. this implies that the clay minerals in the soils of the study area are dominantly expansive. in general, according to the general engineering suitability of the soils (arora, 2003), the soils of the study area are characterized by high compressibility, fair to poor shear strength, and poor engineering workability. the results indicate that they are problematic soils for engineering application with higher swelling-shrinkage potential. mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 48 table 4: classification of soils of the study area based on aashto and uscs system. sample no. aashto classification uscs group symbol group name tp-1 a-7-6(42) ch inorganic clay of high plasticity tp-2 a-7-6(32) mh inorganic silt of high plasticity tp-3 a-7-6(60) mh inorganic silt of high plasticity tp-4 a-7-6(70) ch inorganic clay of high plasticity tp-5 a-7-6(61) mh inorganic silt of high plasticity tp-6 a-7-6(63) ch inorganic clay of high plasticity tp-7 a-7-6(41) mh inorganic silt of high plasticity tp-8 a-7-6(30) mh inorganic silt of high plasticity tp-9 a-7-6(42) mh inorganic silt of high plasticity tp-10 a-7-6(39) mh inorganic silt of high plasticity tp-11 a-7-6(33) mh inorganic silt of high plasticity tp-12 a-7-6(65) ch inorganic clay of high plasticity figure 5: classifications of soils of the study area based on uscs. 3.5. groundwater groundwater influences excavation and construction methods by flowing into excavations, producing seepage forces and uplift pressures, and causing corrosive action (unesco, 1976). hence, groundwater level and quality information are necessary for construction activities. as the well data summarized in table 5 shows, the groundwater exist at shallow depth in different parts of jimma town with static water level as shallow as 0.31 m in boche-bore well. therefore, the influence of groundwater on the foundations could be critical in the town. groundwater level contour map (figure 6) was also prepared from static water level data to suggest possible groundwater flow direction. from the map analysis, it is found that groundwater flow is toward the southwestern direction following the topography. hence, groundwater discharge is relatively higher in the southwestern section of the town leading to a very shallow static water level. therefore, due consideration mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 49 regarding groundwater is very important in case engineering structures are intended to be constructed in this area. 3.6. engineering geological characterization of rocks engineering geological characterization of rocks of the study area was done via in-situ strength testing using schmidt hammer and visual estimation of weathering grade. accordingly, the rocks of the study area are classified based on their unconfined compressive strength (ucs) as per isrm (1978) classification system. according to this classification system, rocks of the study area are classified into three major engineering geological subunits: very high strength, high strength, and very low (soft) rock units. 3.6.1. very high strength rock units these engineering geological subunits include slightly weathered ignimbrite and basalt. table 5: measurement values of water level elevations of the wells well longitude (m) latitude(m) altitude (m) groundwater level elevation (m) groundwater depth (m) ginjo school 264841 852239 1767.97 1764.17 3.80 kito-furdisa 263366 851619 1756.98 1753.98 3.00 ju sport field 260398 852256 1744.85 1742.65 2.20 main campus 1 262846 849088 1737.2 1736.00 1.20 main campus 2 263265 848836 1736.24 1735.44 0.80 airport 259040 849892 1725.48 1724.57 0.91 boche-bore 263734 847830 1722.47 1722.16 0.31 figure 6: groundwater level contours and groundwater flow direction of the study area mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 50 figure 7: engineering geological map (scale 1:25,000) and cross-section of the study area 3.6.1.1 slightly weathered very high strength ignimbrite very high strength ignimbrite rock (figure 7) unit is found in the western, eastern, and southeastern parts of the study area forming cliffs. it is gray in color. it has porphyritic texture (i.e. clasts and groundmass) and is slightly weathered. its ucs value varies from 131.87 to 169.82 mpa. 3.6.1.1. slightly weathered very high strength basalt very high-strength basalt is mostly found at the n and ne part of the study area. it is fine-grained and slightly weathered. the strength of the rock material varies between 107.15 to 194.98 mpa. three sets (nw, se, and ns) joints are dominant. the joints are moderately spaced (250 mm to 300 mm). the joint mekdes habtamu et al. ethiop.j.sci.sustain.dev., vol. 9(1), 2022 51 surface is both smooth and rough. the aperture varies from tight to partly open (0.25 mm to 1 mm). 3.6.2 moderately weathered high strength ignimbrite the high-strength ignimbrite rock unit is found in the nw part of the study area. it is light gray in color and moderately weathered. the strength of the rock material range from 50.18 to 97.72 mpa. 3.6.3. highly weathered very low strength rock unit (tuff) the strength of this rock was too low to be measured using the schmidt hammer during the field survey. the rock of this unit can be peeled with a knife, and hence the compressive strength is considered to be <1 mpa. it is highly weathered, light in color, and has a finegrained texture. 4. conclusion and recommendations the main mappable soil units in the study area are alluvial and residual soils. from grain size analysis, the soils are dominantly fine-grained with gravel, sand, silt, and clay contents ranging from 0% to 0.98%, 0.35% to 4.59%, 24.05% to 55.91%, and 42.16% to 71.36%, respectively. the natural moisture content varies from 41.97% to 62.45% indicating that the water holding capacity of the soils is relatively very high. the liquid limit and plastic limit of soils in the study area range from 66%–101% and 31%–42%, respectively. similarly, the plasticity index also varies from 19%59%, showing that soils of the study are medium to very highly plastic. their free swell potential is also in a range of 33% to 130% indicating that most soils of the study area are characterized by a high degree of expansiveness, and hence various types of structures constructed on soils of the study area are susceptible to considerable damage. according to uscs, soils of the study are classified as high plastic clay (ch) and high plastic silt (mh) and are characterized by high compressibility, fair to poor shear strength, and poor engineering workability. likewise, as per the aashto classification system, the soils are classified as clayey soils (a-7-6) which is unfavorable for subgrade material. from engineering rock characterization, four engineering geological rock units were identified in the study area considering the degree of weathering and compressive strength of intact rock. these engineering geological units include slightly weathered very high strength ignimbrite, moderately weathered high strength ignimbrite, slightly weathered very high strength basalt, and very low strength highly weathered tuff units. moreover, the study area is also highly susceptible to flooding hazards. the design of any civil engineering structures in the town shall consider the high swelling potential of soils of this area. construction of detention dam, drainage networks, diversion canals, and proper waste management is also recommended to minimize the flooding risk in the town. acknowledgment the first author would like to thank adama science and technology university for sponsoring this research work as part of her msc study. the authors also express their gratitude to jimma university, particularly the civil engineering department 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(2021). implications of the engineering geological properties of soils in the implementation of the greater jos master plan, north central nigeria. european journal of engineering and technology research, 6(5): 118-128. doi: 10.24018/ejers.2021.6.5.2530. 34 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 synthesis and luminescent characteristics of (ca4-x-yzbaysrz)(po4)2o:xeu 2+ phosphors as a potential application for white-light emitting diode g. deressa school of applied natural science, department of applied chemistry, adama science and technology university, adama 1888, ethiopia email: abstract a novel tunable redto yellowemitting phosphor,(ca4-x-y-zbaysrz)(po4)2o:xeu 2+ is reported that displays a broad emission from 500 to 800nm, and its emission can be adjusted from red to yellow by changing ba 2+ and sr 2+ doping concentration. x-ray powder diffraction analysis confirmed the phase formation. excitation and emission spectra, and concentration dependence of emission intensity of the phosphor were investigated. the results showed that with increasing ba 2+ /sr 2+ concentration, the emission peak wavelength blue-shift from 594 to 567 nm, and the color can be tuned from red to yellow. when singlephase (ca2.95ba0.5sr0.5)(po4)2o:0.05eu 2+ phosphor is pumped by a blue ingan light-emitting diode we obtain white light with color rending index between 80.0 and 88.0 and color temperatures between 3500 and 5450 k, suggesting that this material is competitive as a color conversion material for solid state lighting. keywords: white light-emitting diode; phosphors; tunable emitting 1. introduction the commercialized white light emitting diodes (wleds) can be generated by combining a blue-emitting ingan-led chip and a yellow-emitting garnet phosphor y 3 a l 5 o 1 2 :c e 3 + ( ya g:c e 3 + ) (bachmann et al., 2009; schubert et al., 2005 and deressa et al., 2015). however, such white light does not have sufficient color rendering properties. the color-rendering index (cri) remains to be improved due to the lack of a full color component from the yellow phosphor. recently, several wled devices fabricated using ultraviolet (uv) chip coupled with a blend of tunable (blue-to-yellow) emitting and red-emitting phosphor, which exhibited favorable properties, deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 35 © adama science & technology university https://ejssd.astu.edu.et including tunable correlated color temperature (cct), tunable commission international del’ eclairage (cie) chromaticity coordinates, and excellent cri values (deressa et al., 2015; setlur et al., 2010; and zhou et al., 2014).unfortunately, the emission tunable range of the phosphor with a single activated ion has been reported is limited to blue to yellow. changing the cation ratio of orthophosphate phosphate can distort the lattices structure due to change in crystal field of the host that causes the broadening spectra of the luminescence.this is also a promising host for lighting and display due to its good thermal stability and high luminescent efficiencies. the eu2+-activated orthophosphatephosphates are good candidates as host structures and offer a number of merits, such as high chemical and low synthesis temperature and physical stability, and they exhibit interesting luminescence (yang et al., 2004; zhou et al., 2013). the motivation of this work was to invesigate a tunable red to yellow-emitting and efficient inorganic phosphors (ca4-x-yzbaysrz)(po4)2o:xeu 2+) that could be applied in uv or blue ledbased solid state white light sources. orthophosphate-phosphor doped with rare earth ions is widely explored as red, green and blue (rgb) phosphors owing to advantages of relatively low sintering temperature, good chemical stability, and satisfactory absorption in the ultraviolent (uv) to blue region (zhou et al., 2013; huang et al., 2008). ca4(po4)2o:eu 2+ is novel red-emitting phosphate phosphors (kottaisamy et al., 1994). to the best of our knowledge, its tunable emitting properties have not been reported in the literature. in this paper, we investigated a tunable redto yellowemitting (ca4-x-y-zbaysrz) deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 36 © adama science & technology university https://ejssd.astu.edu.et (po4)2o:xeu 2+ phosphor. this phosphor was excited by light in uv to blue region and showed tunable red-to-yellow emission. the optical properties of orthophosphate phosphate phosphors were systematically investigated by means of photoluminescence excitation (ple) and emission (pl) spectra, thermal stability, raman, and applications for white light emitting diodes (white-leds). 2. materials and methods 2.1. preparation (ca4-x-yzbaysrz) (po4)2o:xeu2+ phosphate phosphors powder samples of orthophosphate phosphors were prepared by a solid-state reaction. mco3 (99.99%), [m = ca, sr and ba], (nh4)2hpo4 (99.0%), and eu2o3 (99.99%) are weighed, thoroughly mixing and ground in an agate mortar. the mixed powders were then transferred into an alumina crucible, and presintered in a furnace at 500 ℃ for 2 hours in air to eliminate the water and decompose the carbonate. the pre-sintered samples were subsequently cooled down to room temperature and fully ground to form a homogeneous mixture. then the mixture was re-sintered at a high temperature of 1000 to 1300 ℃ for 4 hours under a reducing atmosphere (5%h2/95%n2) for 4 hours. after sintering, the samples were cooled down naturally to room temperature in the furnace. the acquired sintered products were pulverized for further measurements. the nominal molar compositions of the phosphors are: ca4-x-ybaysrz(po4)2o:xeu 2+ (0.01 ≤ x ≤ 0.10, 0 ≤y ≤ 2.5, and 0 ≤ z ≤ 2.5)) (setlur et al., 2010) 2.2. materials characterization the as-prepared samples were characterized by using the following instruments; scanning electron microscope (sem: leo supra 55, carl zeiss) attached deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 37 © adama science & technology university https://ejssd.astu.edu.et with an energy dispersive x-ray spectrometer (edx), x-ray diffractometer (m18xhf sra, mac science), x-ray diffraction (xrd) analysis using a rigaku d/max 2500 with cu k radiation. the measurements of photoluminescence (pl) and photoluminescence excitation (ple) spectra are carried out using a darsa pro-5200 fluorescence spectrophotometer equipped with a xenon lamp as the excitation light source. the thermal quenching characteristics are measured in the temperature range of 25-200 ℃. raman spectra of (ca, sr, ba)4(po4)2o: eu 2+ were carried out at room temperature in the range of 200 to 2000 cm-1 using agiltron, raman spectrometer, which is having excitation nd:yag laser) a excitation laser source (1064 nm). 2.4. led lamp fabrication. the wleds were fabricated using a blue-led chip with a 450 nm excitation wavelength. first of all, the chip was assembled on a led frame and care was taken to prevent the formation of air bubbles between the chip and frame, because it can damage the led when a forward bias current is applied. the semi-transparent silicone epoxy was prepared by mixing two optical encapsulates, i.e., oe-6630 a (base) and oe6630 b (catalyst) in 1:2 ratio. afterwards, the required quantity of (ca2.95ba0.50sr0.50eu0.05)(po4)2o phosphor powders were mixed with the silicone epoxy, kept in a mixer and later kept in a desiccator to remove the air bubbles. finally, it was poured in a dispenser tube. the phosphor mixed epoxy was later dispensed onto the led frame and kept in an oven (@ 120 °c, for 90 min) to harden, and eventually the wleds were characterized by using an ol770 multi-channel spectroradiometer attached with an integrating sphere (deressa et al., 2015). deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 38 © adama science & technology university https://ejssd.astu.edu.et 3. results and discussion 3.1 phosphor synthesis and characterization. fig.1 shows the results of the data collection and structure refinements for (ca2.95 ba0.50 sr0.50 eu0.05) (po4)2o. the single crystal structure data of ca4(po4)2o (icsd no. 2631) was performed as starting reference to approach the actual crystal structure. the final converged weighted-profile of rexp=6.99, rwp= 9.16, rp=7.09 and gof=1.31 is shown in table 1. the (ca2.95 ba0.50 sr0.50 eu0.05) (po4)2o crystallizes in a monoclinic unit cell with space group p21(4) space group with z = 4. in the crystal structure of ca4(po4)2o, the ca 2+ ions have eight different coordination environments, only ca(6) ion is eight-coordinated, and the other ca2+ ions are seven-coordinated (see fig. .1 (b) table 1: rietveld refinement and crystal data of rietveld enhancement and crystal data of (ca2.95ba0.50sr0.50eu0.05)(po4)2o phosphors formula ca3.95(po4)2o:0.05eu 2+ cryst. syst. p21(4) – monoclinic crystal density (g/cm3) 7.229 units, z 4 a (å) 7.012 (11) b (å) 11.979 (13) c (å) 9.481 (9) v (å3) 797.32576(15) β (deg) 90.6(2) rexp (%) 6.89 rwp (%) 9.14 rp (%) 7.06 gof 1.29 deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 39 © adama science & technology university https://ejssd.astu.edu.et figure1: (a) observed (black), calculated (red), and difference (green) synchrotron xrd profiles for the rietveld refinement of (ca2.85ba0.50 sr0.50) (po4)2o:0.05eu 2+. bragg reflections are indicated with tick marks. (b) crystal structure of ca4(po4)2o unit cell viewed in adirection (denget al., 2013). the xrd patterns of (ca4-yzbaysrz)(po4)2o:0.05eu 2+ together with the joint committee on powder diffraction standards (jcpds) card no. 73-1379 are shown in fig. 2. when the sr2+ doping content (z), the diffraction peaks of the obtained sample can be indexed to the standard data except for little shift, indicating that these samples almost are single-phase. when the ba2+ doping content (y), the diffraction peaks of the obtained sample can be indexed to the standard data except for little shift, indicating that these samples almost are single-phase. eu2+/ba2+/sr2+ are incorporated in the host lattice (yang et al., 2004). when the ba2+ doping content (y) is higher than 0.10, the intensity of some crystal planes diffraction peaks increased gradually, such as (200), (210) and (212) which indicated that with the increase of ba2+ ions substiturion, resulted in corresponding crystal face preferred growth. additionally, the diffraction peaks exhibited a shift toward smaller angles with rising doping content of the ba2+ ion, deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 40 © adama science & technology university https://ejssd.astu.edu.et which may be related to the substitution of smaller ca2+ by the lager ba2+. the micromorphology of the crystalline (ca2.95 ba0.50 sr0.50 eu0.05) (po4)2o phosphor sample observed by sem is shown in fig. 3. it is observed that the particles have smooth morphology and the diameters are ranging from 15 to 20 μm. the elemental composition of (ca2.95 ba0.50 sr0.50 eu0.05) (po4)2o sample verified by eds shows (wt %) ca 35.28%, ba 3.23%, sr 3.38, eu 2.25 %, p 16.34 % and o 38.91%. the composition suggested by eds is consistent with stoichiometric weight ratio with reasonable relative error. figure 2: xrd patterns of (ca4-y-zbaysrz)(po4)2o:0.05eu 2+ phosphors figure 3: (a) sem image and (b) eds profile of (ca2.95ba0.50 sr0.50eu0.05) (po4)2o sample deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 41 © adama science & technology university https://ejssd.astu.edu.et the raman vibrational frequencies of v2, v3, and v4 are follows the same phenomenal. the shift in the observed raman frequencies is believed to be due a tightening or enlargement of the molecular po4 3ion as oxygen atoms of neighboring molecules are either drawn near or pushed apart on substitution of cations of different size. the bond length of ba-o/ sr-o are longer than the co in the crystal structure of ba4 po)2o,sr4po4)2o and ca4po4)2o, respectively. the crystal structure of (ca2.95ba0.50sr0.50) (po4)2o:0.05eu 2+ formed from mixed crystal structure of ba4po4)2o,sr4po4)2o and ca4po4)2o as observed from xrd and raman properties of the structures, both xrd and raman spectra of the host (ca2.95ba0.50sr0.50) (po4)2o found between these three hosts of ba5(po4)3cl and sr5(po4)3cl lattices. this indicate that the lattices of (ca2.95 ba0.50 sr0.50) (po4)2o host combined from an expanded ba-o/sr-o and contracted ca-o bonds which create different environments around the sites of eu2+ ions doped in the lattice of (ca2.95 ba0.50sr0.50)(po4)2o phosphor and cause for the blue shifts and spectral broadening of eu2+ activated (ca2.95 ba0.50 sr0.50) (po4)2o phosphors (setlur et al., 2010; im et al., 2010). the excitation and emission spectrum of (ca2.95 ba0.50 sr0.50) (po4)2o:0.05eu 2+ are shown in fig. 5. under 450 nm excitation, there are the broad asymmetric emission spectrum peaking at 567 nm with four broad emission bands centered at 567, 608, 632 and 667 nm, respectively. the broad emission shows that eu2+ has more than one emission center in ca4(po4)2o which belongs to the typical emission of eu2+ ions ascribed to 5d→4f transitions. by gaussian deconvolution, the emission spectrum of (ca2.95 ba0.50 sr0.50)(po4)2o:0.05eu 2+ can be well-decomposed into eight gaussian proflies peaking at 534 deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 42 © adama science & technology university https://ejssd.astu.edu.et nm, 556 nm, 567 nm, 592, 608 nm, 632 nm, 667 nm, 673 nm and 674nm, which can be ascribed to eight different ca2+ sites occupied by eu2+ ions. the refinement shows that the structure of ca4(po4)2o contains eight crystallographically distinct ca2+ sites that can be occupied by eu2+. the eu2+ ions substituting ca2+ ions in the site which has shorter ca-o band distance are expected to experience stronger crystal field strength corresponding to a longer wavelength emission with larger stoke shift, when the crystal environments are analogous. fig. 5illustrates eight kinds of cations ions coordinated with oxygen atoms, corresponding to the eight gaussian profiles in the emission spectrum (schubert et al., 2005; deressa et al., 2015 and wu et al., 2011). it is also observed that the excitation spectrum monitoring by 594 nm exhibits a different spectral profile, which means that the ba/sr substitute ca at diferent site in the lattics and emission bands should be ascribed to different sites occupied by eu2+ ions, which is also in accordance with the above analysis on the crystal structure. figure 4. raman spectra of (ca4-y-zbaysrz) (po 4)2o:0.05eu2+ phosphor deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 43 © adama science & technology university https://ejssd.astu.edu.et the excitation spectrum shows a broad absorption from 300 to 500 nm with different maximum in the range, which corresponds to the 4f7→4f65d1 transition of the eu2+ ions. (ca3.95-y-zbaysrz)(po4)2o:0.05eu 2+ can be efficiently excited by blue light (350~480 nm), which is very advantageous for application in the w-leds combined with highly efficient blue-ingan chips (fig. 6b) (zhouet al., 2014; dorenboset al., 2013 and zhou et al., 2013). figure 5: emission spectra of (ca2.95ba0.50sr0.50)(po4)2o:0.05eu2+ (λex = 450nm) measured emission (black line), fitted curve (red line) and deconvoluted gaussian curve fig. 6(a) shows room temperature normalized pl spectra of (ca3.95ybay)(po4)2o: 0.05eu 2+ phosphors for an excitation wavelength of 450 nm. the emission intensity at 594nm shifted to shorter wavelength as ba2+/sr2+ substituted in the lattices of ca2+ ion. in general, the electronic configuration of eu2+ is 4f7 and 4f65d1 at the ground and excited state, respectively, and the luminescence of eu2+ is ascribed to the 4f65d1into 4f75d0 transition which results in the broad band emission. the emission wavelength of eu2+ depends strongly on the structure of the host crystal through the crystal field splitting of the 5d band and the ground state for the deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 44 © adama science & technology university https://ejssd.astu.edu.et 4f7electronic configuration (zhou et al., 2013; kottaisamy et al., 1994 and huang et al., 2008). figure 6: (a) emission spectra (λex= 450nm) and, (b) excitation (λem= 594) of (ca3.95-y-zbaysrz) (po4)2o: 0.05eu 2+). as stated above, the positions of the 4f6d1 levels are much more influenced by the outer crystal field interaction than the 4f7 levels and highly depend on the crystalline environment around eu2+ ion, so significant optical changes are expected if local structure around the eu2+ center is different (schubert et al., 2005; deressa et al., 2015). in case of as-synthesized ca3.95-y-zbaysrz)(po4)2o:0.05eu 2+ phosphors, the environment around eu2+ ions have uniform crystal structures. the unit cell volume of ca4(po4)2o is less than ba4(po4)2o and sr4(po4)2o hosts due to ionic size difference of sr2+/ba2+ and ca2+ ions and the ionic size of eu2+ less than that of sr2+and ba2+ ions, upon eu2+ doping in to the above hosts. the is ba4(po4)2o and sr4(po4)2o less than slightly distortion than deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 45 © adama science & technology university https://ejssd.astu.edu.et ca4(po4)2o hosts because of the size difference between eu2+ and ba2+ /sr2+ bigger than the size of ca2+ ions. therefore, pl spectrum of the dopant eu2+ ion experienced strong crystal fields (blue shift) and low symmetry (broaden) in c a 4 y z b a y s r z ) ( p o 4 ) 2 o than ca4(po4)2o:0.05eu 2+ phosphors, due to local structure (symmetry) difference around eu2+ center in the respective hosts. when content of ba2+/sr2+ ions increased from (y = 0.1 to 1.0, and z = 0.1 to 1.0) the emission peak positions gradually move toward longer wavelengths from 549 nm to 594 nm, and in addition, the fwhm of eu2+ ions emission broaden from 140 nm to 210 nm (see fig. 6(a)). for (ca3.95ybay)(po4)2o:0.05eu 2+ phosphors, about 70 nm shift and 51 nm broadening allow highly colortunable phosphors by changing the content of ba2+/sr2+ ions (ronda et al., 2008; sommerdijk et al., 1974 and wegh et al., 1999). this indicate that the lattices of (ca2.95ba0.50sr0.50)(po4)2o host combined from an expanded ba-o/sr-o and contracted ca-o bonds which create different environments around the sites of eu2+ ions doped in the lattice of (ca2.95ba0.50sr0.50)(po4)2o phosphor and cause for the blue shifts and spectral broadening of eu2+ activated (ca2.95 ba0.50 sr0.50) (po4)2o phosphors. fig. 7 shows the emission spectra of ca4-x(po4)2o:xeu 2+ with different eu2+ concentration. it can be seen from the fig., the optimal eu2+ content was about x= 0.10. when the content of eu2+ ions was over x = 0.05, concentration quenching occurred and emission intensity decreased with increasing eu2+ ions concentration. moreover, emission wavelength as well as emission intensity of the ca4x(po4)2o:xeu 2+ phosphors were changed by varying the concentration of eu2+ ions. as the concentration of eu2+ ions in the deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 46 © adama science & technology university https://ejssd.astu.edu.et host lattice was increased, the emission wavelength shifted slightly to a shorter wavelength. with an increase of the eu2+ concentration x , the integrated emission intensity slightly increases with a breaking point x ≈ 0.10, which establish its higher emission efficiency. upon excitation at a wavelength of 450 nm, the external quantum efficiency of (ca2.95 ba0.50 sr0.50) (po4)2 o:0.05eu2+ and (sr,ba)2sio4:eu 2+ well known yellow phosphor are determined to be 38.7% and 70.9%, respectively. the lower quantum efficiencies of (ca2.95 ba0.50sr0.50)(po4)2o:0.05eu 2+coul d be further enhanced by process optimization. 3.2. application to white leds. figure 8 shows photometric and colorimetric quantities of the white leds under the following applied currents: 20, 50, 100, 150, 200, 250, 300 and 350ma. when the applied current was 350ma, the white led have cie color coordinate of (0.3354, 0.3448) at a white light (tc = 5500 k) and an excellent ra of 86.the cie color coordinates shifted towards the white light region along the planckian locus, the value of ra decreased from 91.6 to 86.0 and the luminous efficiency decreased from 21.5 to 16.5 lm/w as the applied current was increased. in comparison with the blue ingan chip pumped with yag:ce3+ phosphor (ra = 75, cct=7756k), and lasr2alo5 phosphor (ra = 8585, cct = 4200-5500 k) (deng et al., 2013; huang et al., 2008), the white leds in this study shows higher ra value and lower cct value. therefore, the (ca, ba, sr)4(po4)2o:eu 2+ phosphors are promising for application in excellent ra white leds. deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 47 © adama science & technology university https://ejssd.astu.edu.et figure 7: the emission spectra of ca4-x(po4)2o:xeu 2+ with different eu2+ concentration figure 8: cie chromatic coordinates, ra and luminous efficiency (the inset) of the white led using (ca2.95ba0.50sr0.50)(po4)2o:0.05eu 2+ under various applied currents. the planckian locus line and the points corresponding to color temperatures are indicate 4. conclusions in summary, a tunable red-toyellowemitting ca3.95-y-zbaysrz) (po4)2o:0.05eu 2+ phosphors have been reported. the excitation spectrum shows broad band in the near-ultraviolet, ultraviolet and blue region, which matches well with blue chips (ca, ba, sr)4 deressa g. ethiop. j. sci. sustain. dev., 5 (1), 2018 48 © adama science & technology university https://ejssd.astu.edu.et (po4)2o:eu 2+which is excitable over a broad range from 500 to 800nm when its emission can be adjusted from reg to yellow by changing ba2+/sr2+ doping concentration. by applying (ca2.95ba0.50sr0.50) (po4)2 o:0.05 eu2+ phosphor on blue chip, we obtained a white led device with high ra of 86 and cct value of 5450 k. therefore, with the interesting tunable emission property, (ca, ba) 4(po4)2o: eu 2+ phosphor has great application potential as a good color conversion material for solid state lighting. acknowledgment this research was supported by school of applied natural science, adama science and technology university under eight cycle astu research grant. the laboratory activities were done in the department of display science and engineering, pukyong national university, busan, 608-737, republic of korea. references bachmann, v., ronda, c., and meijerink, a., (2009). temperature quenching of yellow ce3+ luminescence in yag:ce, chem. mater., 21, 2077. deressa, g., park, k.w., jeong, h.s., lim, s.g., kim, h.j., jeong, y.s., and kim, j.s., (2015). spectral broadening of blue (sr, ba)5 (po4)3cl: eu2+ phosphors by changing ba2+/sr2+ composition ratio for high color rendering index, j. lumin. 161, 347. dorenbos, p., (2013). a review on how lanthanide impurity levels change with chemistry and structure 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https://www.sciencedirect.com/science/article/pii/s0925838814009013 20 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper ambient air quality monitoring procedure via estimation of cadmium and lead content in atmospheric dust using vegetable leaves okponmwense moses , ehinomen benjamin aimudogbe department of chemistry, faculty of physical sciences, university of benin, benin city. nigeria article info abstract article history: received 29 august 2022 received in revised form 09 november 2022 accepted 13 november 2022 dust emitted into the air through human activities reduces air quality because it comes along with its deleterious constituents. this study aims to monitor the ambient air quality via the estimation of cadmium and lead concentration in the dust-polluted atmospheric environment using vegetable leaves. leaves of pumpkin (telfairia occidentalis) and green (amaranthus hybridus) vegetables obtained from oba, ekiosa, new benin, and ikpoba-hill markets in edo state, nigeria, were washed with de-ionized water, spread, and exposed on tables placed at ten different points, 10 meters apart near the roadside outside and inside each market from 8:00 am to 6:00 pm every day (monday friday) for three months (from november to march). the cadmium and lead pollutants in the dust deposit were analyzed using atomic absorption spectrophotometer after wet digestion of the different collectors. the study revealed that there was no cadmium content in the dust deposited on the vegetable leaves exposed inside each market. atmospheric dust deposited on the vegetable leaves outside each market had cadmium content up to the tune of ≤0.01mg/kg. the study also revealed that the atmospheric dust inside and outside each market contained lead content. the lead content in the dust deposit obtained from outside each market ranged from 0.03-1.04 mg/kg, and the lead content in the atmospheric dust deposit obtained from inside each market ranged from 0.02-0.69 mg/kg. the air quality index (aqi) prediction for cadmium inside and outside the market atmosphere was very good (very clean). however, for the lead contaminant, the aqi rating outside and inside the market ranged from moderate (fairly clean) to very poor (severely polluted). ekiosa market was very poor (severely polluted) and the ikpoba-hill market was moderate (fairly clean) due to lead contaminants in dust deposited due to human activities and heavy vehicular traffic. keywords: vegetable leave, monitoring, atmosphere, dust deposit, pollutants, roadside. 1. introduction dust is one of the air pollutants that can be emitted into the air thereby reducing air quality because of its deleterious constituents (mehrizi et al., 2017). dust deposition is an ambient air quality indicator monitor (atef et al., 2020). the constituents and quantity of poisonous elements in dust are pointers to the poor quality of the urban environment (hemati and rahimi, 2020; kaonga et al., 2021; vanegas et al., 2021). dust particle comprises sizeable amounts of poisonous substances that present threats to the health of living corresponding author, e-mail: okponmwense.moses@uniben.edu https://doi.org/10.20372/ejssdastu:v10.i1.2023.540 organisms and ecosystems (esfandiari et al., 2019). dust is airborne particulate matter in the form of fine powder with tiny solid particles ranging in size from beneath 1 μm to 100 μm. dust is either lying on the ground or the surface of objects or scattered or suspended in the air (nwosu et al., 2016; srivastava et al., 2020; kaonga et al., 2021). dust chemical constituents are inconsistent and linked with the features of the emission sources. the dust particles contain pollutants such as “inorganic” http://www.ejssd.astu.edu/ mailto:okponmwense.moses@uniben.edu okponmwense moses and ehinomen benjamin aimudogbe ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 21 (heavy metals), “organic” (polycyclic aromatic compounds) and biological materials (microorganisms), depending on the source of the dust (sun, 2017; kumari et al., 2021; vanegas et al., 2021). the traffic zone is deemed the main provider of heavy metal emission and dust particles ≤10 μm (javid et al., 2021). the existence of heavy metals in dust existing in the air raises the concentration of these elements in the human body via ingestion, respiration as well as skin absorption (abdel et al., 2016; javid et al., 2021; hamed et al., 2022). owing to fast-tracked social and economic growth, there is a rise in heavy metals in urban road dust due to anthropogenic sources which comprise traffic discharge such as vehicle exhaust particles, tire attrition particles, eroded street surface particles, brake lining attrition particles, etc. (rajeswari and sailaja, 2014; osakwe and okolie, 2015; altaf et al., 2021); industrial discharge such as power plants, coal combustion, metallurgical industry, auto repair shop, chemical plant, etc.; domestic discharge such as electric generator discharge, building and pavement surface wear away, atmospheric deposits and the like, thereby causing a growing number of pollutants to be regularly emitted into the environment (masindi and muedi, 2018; okunlola, 2019; xu et al., 2021; su, 2022). ingestion of dust particles loaded with high concentrations of heavy metals may trigger respiratory and cardiovascular diseases, cancer, birth flaws, central nervous system impairment and death (al-dabbas et al., 2018; skorbiłowicz et al., 2020; kaonga et al., 2021). lead is released as lead (ii) oxide (pbo) into the atmosphere through oil combustion, as lead (ii) sulphate (pbso4) and pbo through non-ferrous metal production, and it is emitted as lead (ii) chloride (pbcl2) during coal combustion, refuse incineration and vehicle exhaust emission. cadmium is released into the air as cadmium (ii) oxide (cdo) by anthropogenic sources, as cadmium (ii) sulphide (cds) through coal combustion, as cadmium (ii) chloride (cdcl2) through refuse incinerator, and as elemental cadmium in the course of high-temperature means, for instance, organic fossil fuel combustion and waste incineration (w.h.o, 2007; engwa et al., 2019). cadmium triggers off injuries to the kidney, and acute pulmonary effects as well as kidney cancer. it also affects the liver and gastrointestinal tract. similarly, lead injures the kidney, affects the nervous system, and triggers mental lapse (ojo, 2017; skorbiłowicz et al., 2020). kananke (2014) asserted that nearly all eaten green leafy vegetables sold along the roadside open markets in highly urbanized areas are contaminated with heavy metals. metals monitoring in atmospheric dust deposits is conventionally executed by using collectors which are dispersed all over areas envisioned to be monitored. in this study, leaves of pumpkin (telfairia occidentalis) and green (amaranthus hybridus) vegetables were used as our dust collectors based on their availability, cheapness, toughness and ease of digestion. this research is aimed at estimating cadmium and lead concentration in the dust-polluted atmospheric environment as well as predicting its ambient air quality with the aid of vegetable leaves as a dust collector. 2. materials and methods 2.1. study area, sampling & sample preparation the study areas used for this research were oba market (om) (6020’5” n; 5037’11” e), the ekiosa market (em) (6019’24” n; 5038’11” e) and new benin market (nbm) (6021’13” n; 5037’53” e) (all located in oredo local government area, nigeria) as well as ikpoba-hill market (ihm) (6020’56” n; 5039’33” e) located in ikpoba-okha area in edo state, nigeria. these markets were selected for this study because the roads on the sides of these markets are busy with high human activities as well as vehicular traffic. the monitoring systems were used in collecting dust samples before analysing the composition of pumpkin leaves (telfairia occidentalis) and green (amaranthus hybridus) vegetables which were purchased and used at each market. after the leaves had been acquired, they were washed in de-ionized water, spread and exposed on tables with a height of 1.0m (sitting height) placed at ten different points the interval of 10 meters from each other near the roadside outside each market mentioned above from 8:00 am to 6:00 pm every day (monday friday) for three months from november to march. likewise, the vegetables were also exposed on tables inside the market about 150 meters from the roadside. after everyday exposure, the leaves from the different vegetables were plucked off separately and shared into two equal portions of the same weight. one portion was washed thoroughly in de-ionized water and the other okponmwense moses and ehinomen benjamin aimudogbe ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 22 portion was left unwashed. this procedure was carried out for vegetables exposed inside and outside the market near the roadside. each portion of the leave from the different vegetables was oven-dried to constant weight and crushed in a mortar to powdery form and sieved with 53μm mesh size (270-astm-e11). one gram (1g) of the powdered vegetable leaves from each portion was weighed and digested using a wet digestion procedure adapted from motsara and roy (2008). thereafter, the cadmium and lead content in the samples was analyzed using atomic absorption spectrophotometer (aas) model 210vgp – buck scientific. this approach to estimating the cadmium and lead in atmospheric dust deposits inside and outside each market was based on data obtained from atmospheric dust deposited on the leaves of the vegetables. the total cadmium and lead in the atmosphere inside and outside each market were estimated based on separate assessments for washed and unwashed vegetable leaves after atmospheric deposition of dust, using equation 1: adhm = hmuwv hmwv (1) where adhm = total heavy metal in atmospheric dust, hmuwv = total heavy metal in unwashed vegetable leaves, and hmwv = total heavy metal in washed vegetable leaves. air quality index (aqi) is a scale to characterize the extent of ambient air pollution at a particular monitoring location during a certain monitoring period as a result of the strength of human activities that occur in an environment. aqi is a rating scale for outdoor air and is rated inversely to the quality of air, that is, the lower the aqi value, the better the air quality. air quality rating of each quality parameter or pollutant (here cd and pb only) was computed using equation (2) (njoku et al., 2016; hashmi et al., 2017): q = po ps (2) where, q = air quality index (aqi), po = the observed value of the air quality parameter pollutant (cd, pb), ps= the standard value for that pollutant recommended by who. it is assumed that all the parameters have equal importance, so only the unweighted air quality indices are calculated (ravikumar et al., 2014). the geometric unweighted aqi may be computed from the air quality rating q by taking their geometric mean. aqi = [π𝑄𝑖=1 𝑛 ]1/𝑛 (3) this relation is made easier to some extent by taking the common logarithm on both sides assuming 𝜋 = 1 then, log aqi = 1 𝑛 [log 𝑄1 + log 𝑄2 + … + log𝑄𝑛] (4) combining the right-hand side factors log aqi = 1 𝑛 [ ∑ log𝑄𝑖 𝑛 𝑖=1 ] (5) hence, aqi = antilog ( 1 𝑛 [ ∑ log𝑄𝑖 𝑛 𝑖=1 ]) (6) the ambient air quality index can be calculated using equations 1 and 6. the seven grades of air quality categories include: very clean (aqi < 10), clean (10 ≥ aqi < 25), fairly clean (25 ≥ aqi < 50), moderately polluted (50 ≥ aqi <75), polluted (75 ≥ aqi < 100), highly polluted (100 ≥aqi < 125) and severely polluted (aqi ≥ 125). based on these standard aqi values, the air quality of the observed air samples can be compared and inferred (ravikumar et al., 2014). the five-grade air quality scale, according to njoku et al., (2016), is as follows: a = very good (0 -15), b = good (16 -31), c = moderate (32 – 49), d = poor (50 – 99) and e = very poor (100 and over). 2.2.quality assurance suitable quality assurance and safety measures were obeyed to guarantee test results' dependability. analytical and trace-metal grades reagents/chemicals, de-ionized water as well as washed glassware and utensils were utilized during the research. samples were carefully managed to lessen cross-contamination. reagent blank determinations were also carried out to correct the instrument readings. 2.3.statistical analysis descriptive statistics such as mean, standard deviation, and analysis of variance (anova) were carried out to correlate the significant differences for the examined metals between the different selected sites. okponmwense moses and ehinomen benjamin aimudogbe ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 23 3. results and discussion 3.1. mean content of cadmium and lead in dust deposited on washed and unwashed vegetables leaves the results obtained from the study showing the content of cadmium and lead in washed and unwashed vegetables after exposing them outside and inside the different markets are presented in table 1 and table 2 in that order. the results obtained for vegetable leaves exposed to … outside the markets (table 1) show that the values of the amount of lead in atmospheric dust deposited on the unwashed green vegetable leaves were higher than those obtained in the atmospheric dust deposited on the pumpkin leaves probably due to adsorption or roughness of leave surfaces. the lead content on the washed vegetable leave depicted the value of lead in the vegetable from the source farm. the lead amount from the washed green leave was lesser than that from the washed pumpkin leaves depending on the farm source except for the vegetables from the new benin market (table 1). however, the amount of lead observed from the unwashed vegetable leaves was higher than the amount from the washed vegetable leaves, indicating that lead-laden dust was deposited on the unwashed vegetable leaves due to high vehicular traffic as well as other human activities. likewise, the amount of cadmium in the dust deposited on the unwashed vegetable leaves was higher. the value of cadmium obtained from the washed vegetable leave was below the detectable level (bdl), indicating that the cadmium content in the vegetable leave used for this study was originally below the detectable level from the farm source except for the vegetable leave used in ekiosa market, which contained 0.01mg/kg from farm source. table 1: mean content of cadmium (cd) and lead (pb) on washed and unwashed vegetables leaves after exposure outside the market per day. collector vegetable locations unwashed leaves washed leaves cd (mg/kg) pb (mg/kg) cd (mg/kg) pb (mg/kg) pumpkin oba market 0.01± 0.003 1.24± 0.02 bdl 0.74± 0.01 green oba market 0.01± 0.002 1.47± 0.03 bdl 0.43± 0.01 pumpkin ekiosa market 0.02± 0.005 0.72± 0.01 0.01± 0.002 0.36± 0.05 green ekiosa market 0.01± 0.003 0.97± 0.02 0.01± 0.002 0.30± 0.04 pumpkin new benin market 0.01± 0.002 0.82± 0.02 bdl 0.45± 0.05 green new benin market 0.01± 0.003 1.12± 0.02 bdl 0.86± 0.01 pumpkin ikpoba-hill market 0.01± 0.002 0.58± 0.01 bdl 0.55± 0.01 green ikpoba-hill market 0.01± 0.002 0.74± 0.02 bdl 0.36± 0.05 bdl= below detectable level table 2: mean content of cadmium and lead in washed and unwashed vegetables leaves after exposure inside the market per day collector vegetable locations unwashed leaves washed leaves cd (mg/kg) pb (mg/kg) cd (mg/kg) pb (mg/kg) pumpkin oba market bdl 1.07±0.02 bdl 0.63±0.01 green oba market bdl 0.84±0.03 bdl 0.63±0.02 pumpkin ekiosa market 0.01±0.002 0.63±0.01 0.01±0.002 0.20±0.01 green ekiosa market 0.01±0.002 0.89±0.04 0.01±0.002 0.20±0.01 pumpkin new benin market bdl 0.45±0.02 bdl 0.20±0.02 green new benin market bdl 0.86±0.03 bdl 0.56±0.02 pumpkin ikpoba-hill market bdl 0.57±0.01 bdl 0.55±0.01 green ikpoba-hill market bdl 0.58±0.01 bdl 0.36±0.01 bdl= below detectable level okponmwense moses and ehinomen benjamin aimudogbe ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 24 the results obtained from vegetable leaves exposed inside the market (table 2) show that the amount of lead in the atmospheric dust deposited on the unwashed green vegetable leaves was higher than that in the atmospheric dust deposited on the pumpkin leaves except for oba market, where the amount of lead from the atmospheric dust deposited on the pumpkin leaves was higher than that of the green vegetable. the amount of lead observed from the unwashed vegetable leaves was higher than that from the washed vegetable leave, indicating that lead-laden dust was deposited on the unwashed vegetable leaves even inside the market. this could be due to the use of diesel and petrol engine grinding machines as well as other human activities inside the market. the cadmium content in the dust deposited on the unwashed and washed vegetable leave was below detectable level except for pumpkin leave and green leaves exposed at ekiosa market which implies it was from the farm source. 3.2. mean content of cadmium and lead in the atmospheric dust deposited on vegetable leaves the results of the amount of cadmium and lead obtained in the atmospheric dust deposited on the different vegetable leaves outside and inside each market per day are presented in table 3. in all the market locations, the values of cadmium content obtained in the atmospheric dust deposited on the vegetable leaves exposed outside the market were higher than the values exposed inside the market. in like manner, the lead content obtained in the atmospheric dust outside the market was higher than that obtained in the atmospheric dust inside the market. however, the lead content in dust deposited on the leaves of green vegetables and pumpkins inside the ekiosa market was higher than those obtained from outside the market (table 3). this indicates that there could be heavier human activities resulting in the emission of lead inside the ekiosa market compared to the other three markets. the lead content in the atmospheric dust deposited on pumpkin leaves from outside each market ranged from 0.03-0.50mg/kg, and the atmospheric dust deposited on the green leaves from outside each market ranged from 0.26-1.04mg/kg. this observation could be a result of the higher adsorptive strength of the green leaves for lead compared to pumpkin leaves. the lead content in the atmospheric dust deposited on the pumpkin leaves inside each market ranged from 0.020.44mg/kg, and the atmospheric dust deposited on the green leaves inside each market ranged from 0.210.69mg/kg and this observation could be attributed to the fact that the green leaves had higher adsorptive strength for lead compared to pumpkin leaves. the analysis from the study revealed that there was no cadmium content in the atmospheric dust deposited on both vegetable leaves exposed inside the market, indicating that whatever amount of cadmium observed table 3: mean content of cadmium and lead in the atmospheric dust deposited on the different vegetable leaves outside market and inside each market per day collector (with a location in abbreviation s) outside market dust inside market dust cd mg/kg pb mg/kg cd mg/kg pb mg/kg pumpkin(om )) 0.01 0.50 bdl 0.44 green(om) 0.01 1.04 bdl 0.21 pumpkin(em ) ) 0.01 0.36 0.00 0.43 green(em) 0.00 0.67 0.00 0.69 pumpkin(nb m) 0.01 0.37 bdl 0.25 green(nbm) 0.01 0.26 bdl 0.30 pumpkin(ih m) 0.01 0.03 bdl 0.02 green(ihm) 0.01 0.38 bdl 0.22 who, 2004 2.0 0.5 2.0 0.5 bdl= below detectable level okponmwense moses and ehinomen benjamin aimudogbe ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 25 concerning vegetables exposed inside the market was from a farm source; this implied that there was no cadmium content inside the market atmosphere. however, due to heavy traffic and other human activities outside the markets, it was observed that the atmospheric dust deposited on the vegetable leaves outside the markets had some content of cadmium up to the tune of 0.01mg/kg. we observed that the cadmium content in the atmospheric dust deposit obtained from the deposit on green leave outside the ekiosa market was the least, with 0.00mg/kg. this study revealed that there was some cadmium content in the outside market atmosphere. however, the cadmium content in the atmospheric dust outside the markets was below the who standards of 2.0 mg/kg (who, 2004). the value of lead content in the atmospheric dust deposited on the vegetable leaves inside and outside the markets revealed that the atmospheric dust inside and outside the market was contaminated with lead content. the lead content present in the atmosphere inside the market could be due to petrol and diesel engine grinding machines and some other anthropogenic activities, while the lead content in the atmospheric dust outside the market was probably due to heavy vehicular traffic and other anthropogenic activities such as fossil fuel combustion as well as waste incineration. 3.3. prediction of air quality outside and inside each market atmosphere prediction of air quality outside and inside each market atmosphere per day for cadmium and lead contaminants vis-à-vis who standards were made using the estimations obtained from the air quality index (aqi) (table 4). the aqi estimates for cadmium inside and outside the atmosphere of each market surveyed were very good (or very clean), rated 'a' that is its air quality index was less than 10.00 (aqi< 10) (table 4). the air quality index revealed that the atmosphere outside and inside oba market (om) was very poor (or highly polluted) and poor (or polluted) respectively with the use of pumpkin leaves. likewise, the air quality rating for the atmosphere outside and inside oba market (om) was very poor (or severely polluted) and moderate (or fairly clean) respectively with the use of green leaves due to lead contaminant. the air quality index rating revealed that the atmosphere outside and inside ekiosa market (em) was poor (moderately polluted or polluted) with the use of pumpkin leaves, whereas the rating with the use of green leave revealed that the atmosphere outside and inside ekiosa market (em) was very poor (severely polluted) due to lead contaminant. the atmosphere outside and inside the new benin market (nbm) was rated poor (or moderately polluted) due to lead contaminants with the use of pumpkins or green leaves. the air quality rating with the use of pumpkin leaves table 4: air quality index (aqi) outside and inside each market atmosphere per day for cadmium and lead contaminants. collector (with a location in abbreviations) outside market dust inside market dust cd (mg/kg) aqi pb (mg/kg) aqi cd (mg/kg) aqi pb (mg/kg) aqi pumpkin(om)) 0.01 0.50 0.50 100.00 bdl 0.00 0.44 88.00 green(om) 0.01 0.50 1.04 208 bdl 0.00 0.21 42.00 pumpkin(em) ) 0.01 0.50 0.36 72.00 0.00 0.00 0.43 86.00 green(em) 0.00 0.00 0.67 134.00 0.00 0.00 0.69 138.00 pumpkin(nbm) 0.01 0.50 0.37 74.00 bdl 0.00 0.25 50.00 green(nbm) 0.01 0.50 0.26 52.00 bdl 0.00 0.30 60.00 pumpkin(ihm) 0.01 0.50 0.03 6.00 bdl 0.00 0.02 4.00 green(ihm) 0.01 0.50 0.38 76.00 bdl 0.00 0.22 44.00 who standard, 2004 2.0mg/kg 0.5mg/kg 2.0 mg/kg 0.5 mg/kg bdl= below detectable level okponmwense moses and ehinomen benjamin aimudogbe ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 26 revealed that the atmosphere outside and inside ikpoba hill market (ihm) was very good (or very clean). however, with the use of green leave, the atmosphere outside ikpoba hill market was poor (or polluted) and the atmosphere inside the market was moderate (or fairly clean) due to lead contaminant. 4. conclusion this study has usefully determined the quantity of cadmium and lead in atmospheric dust in a polluted atmosphere as well as predicted the air quality inside and outside the market atmosphere with the use of vegetable leaves as a collector. this procedure was not affected by heavy metal interference from the farm soil or accumulated metals in the vegetable leaves because the washed and unwashed vegetable leaves were from the same source, thus cancelling out the effect of heavy metal interference from the farm source (a kind of levelling effect). this assessment procedure has portrayed the presence and estimation of cadmium and lead in atmospheric dust and predicted their air quality due to the effect of human activities and vehicular traffic. implication: monitoring, evaluating, and assessing environmental air quality and effects related to cultural heritage are very important to allow for timely action of preventing irreversible losses. the findings herein depict a means of obtaining baseline data that will help create awareness of the consequences of vehicular traffic, fossil fuel combustion as well as incineration of waste near the markets in the oredo and ikpoba-okha local government area. this ambient air quality monitoring procedure for determining cadmium 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(2000). air quality guidelines for europe, 2nd ed.. world health organization. regional office for europe: https://apps.who.int/iris/handle/10665/107335 world health organization. regional office for europe & joint who/convention task force on the health aspects of air pollution. (2007). health risks of heavy metals from long-range transboundary air pollution. world health organization. regional office for europe: https://apps.who.int/iris/handle/10665/107872 xu, z., mi, w., mi, n., fan, x., tian, y., zhou, y. and zhao, y. (2021). heavy metal pollution characteristics and health risk assessment of dust fall related to industrial activities in desert steppes. peerj 9:e12430: https://doi.org/10.7717/peerj.12430 https://apps.who.int/iris/handle/10665/107335 https://apps.who.int/iris/handle/10665/107872 38 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper investigation of a lodged bullet inside a human brain using computed tomographic (ct) imaging wubante mehari wollelaw1, getasew admasu wubetu2,3 , getnet yitayew tessema4 1department of physics, college of natural science and computational, debre markos university, debre markos, ethiopia 2department of physics, college of science, bahir dar university, bahir dar, ethiopia 3department of physics, college of natural and computational science, addis ababa university, addis ababa, ethiopia 4department of radiology and imaging, college of medicine and health science, bahir-dar university, bahir dar, ethiopia article info abstract article history: received 02 august 2022 received in revised form 09 december 2022 accepted 12 december 2022 we reported the location of a lodged bullet inside a human brain from the 2d and 3d images using computed tomography (ct). it is based on the scanning of the hard and the soft tissues of the brain as well as a bullet by x-ray photons on the circular 3600 ccd detectors. the absorption on the target brain and the bullet had significant differences in the measured current (ma) and the mapped hounsfield unit (hu) as a function of the number of slices. the 2d and the reconstructed 3d images displayed the brain soft tissue, which was dark with low hu compared to the white in the bullet part with a higher hu. the attenuation coefficients of a bullet with copper (cu) and the skull of the brain with calcium (ca) were higher than that of the brain soft tissues with hydrogen (h) and oxygen (o). a typical example is the observation of the image at the center of the slices displayed brighter at 3071 hu. 3d structures of brain images were generated and visualized in different viewing positions. the measured value for a lodged bullet was 11.28 cm away from its entry (frontal), 7.92 cm from the back, and 6.96 cm deep, down from the upper part of the brain. based on our analysis, the bullet is located in the left hemisphere, which is part of the hypothalamus and parity. keywords: lodged bullet investigation, computer tomography, attenuation coefficient, hounsfield value, x-ray tomography, ct brain imaging 1. introduction computed tomography (ct) scan is one of the diagnostic tools used to diagnose a patient with a foreign metallic body inserted in the brain. it can image crosssections with a series of x-ray projections taken from different angles around the patient and captured by the detectors (landis and keane et al., 2010). the new design of ct has a revolutionary impact on clinical practice and investigation in forensic medicine for the observation of foreign bodies embedded in a person (de beer et al., 2008). ct imaging is a highly acceptable method of investigating a lodged bullet inside the corresponding author, e-mail: getasew.wubetu2@mail.dcu.ie or getasew.admasu@bdu.edu.et https://doi.org/10.20372/ejssdastu:v10.i1.2023.531 human brain (gascho, 2021; bolliger, 2021; thali, 2021a). the ct has high spatial resolution and detections at different angles for taking the capture of different slices of 2d images and later building them up to the reconstructed 3d images (liu, 2022; gascho et al.,2020). previous studies have shown that ct allows accurate detection and classification of foreign metals such as cardiac pacemakers, ferromagnetic vascular clips, and nerve simulators (nguyen et al., 2017). the detection of a bullet inside the brain has been studied by different authors such as gascho et al., (2020). x-ray http://www.ejssd.astu.edu/ mailto:getasew.wubetu2@mail.dcu.ie mailto:getasew.admasu@bdu.edu.et wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 39 radiation can cause permanent damage to a brain during scanning so proper dose and careful detection are needed (gascho, 2020b; bolliger, 2021b and thali, 2021b). such detection can help to look at the hidden part of the brain with inserted metal as the attenuations of the metals; these attenuations of metals are different: the hard and soft tissues of the brain (bolliger and thali, 2021b). it has been observed from the 2d and the reconstructed 3d images that the attenuation coefficient of cu is greater than that of ca and soft tissues (seletchi and duliu, 2007). in this work, we investigated a lodged bullet inside the dead body of a 25-year-old man using ct imaging. the 2d images were taken from felege hiwot referral hospital and the reconstructed 3d images from the 2d images by radiant viewer software. then, the location of the bullet in the brain was determined quantitatively and qualitatively from the measured current values. it is derived from the attenuation of the incident x-ray source detection on both the hard and soft tissues of the brain as well as the bullet in the form of the measured current and the mapped hu. 2. materials and methods 2.1.instrumentation figure 1 displays the optima ct-540 scan machine at felege hiwot specialized hospital in bahir dar, ethiopia. this machine has three main parts: an x-ray source, detectors, and a circular sample stage. the x-ray source was rotated through the gantry and equipped with 3600 detectors in a circular ring-like structure. standard imaging protocols were used to image the bullet embedded in the brain of the dead body of a 25-year-old man who died by a gunshot. the key input parameters were set for the ct scan with a peak voltage of 120 kv, current scout image of 10 ma, slice thickness of 0.625 mm, scanning time of 2s, and the helical acquisition protocol. the data acquisitions were taken step-by-step for measuring the 2d images at different projections. 2.2.imaging procedure in the imaging process, the first thing is to keep the patient inside the gantry on the ct scan and lay him down on the examination table in the appropriate position. the x-ray beam was focused onto the brain of the dead body of a man that follows a spiral path of rotation to be imaged by each 3600 ccd detector in the circular directions. the input parameters were set with a low radiation dose to produce quality images. normally, there is a standard procedure for taking the patient’s 2d images by setting the noise management that should be pre-set to filter out unnecessary data to be shielded and set at lower peak voltage settings to accomplish the lowest possible dose necessary. then, the ct scan was set to measure the cross-sectional images of 2d slices and further constructed the 3d image (gruetzemacher et al., 2018). generally, the technologist took the order to the patient to avoid any movement during the scan; hence, this will be important in taking quality images of the examination (fahrni et al., 2017). the ct computer program process had a large volume of data to create two-dimensional crosssectional images of a patient’s head part which were then displayed on a monitor. then, the image processing was completed using radiant viewer software. the scout and slices were generated from the ct images taken. 2.3.the physics of x-ray computed tomography the x-ray radiation depends on parameters such as intensity, attenuation, wavelength, and microstructural parameters of the human brain (sagsoz et al., 2010). x-ray tomography was used to visualize the hard and soft tissues alternatively (said, noor, and yueniwati, 2014). appropriate software is used for better efficiency, higher sensitivity, faster exposure, and dynamic imaging (cong., et al 2011). figure 2 shows the basic principle that governs the interaction of the x-ray with the sample to give a 2d image projection constructed to the 3d image. assuming that the x-rays are a single energetic source, the intensity i1 of an x-ray beam of incident intensity i0 transmitted beam through a small volume of tissue having thickness x and attenuation coefficient µ1 (turbell et al., 2001).can be written based on beer-lambert law as: x eii 1 01   (1) the scanning of the x-rays passes from one side to the other with the charge coupled device (ccd) detection recording the attenuated coefficient for both the bullet and the brain's soft and hard tissues. the intensity of the attenuated x-ray source is given by (chamard et al., 2010):    n ii x eii 1 0  (2) where μi and xi are the linear attenuation coefficient of, and path length through, the material, i. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 40 figure 1: the ct machine is displayed in two separate rooms for medical imaging in felege hiwot specialized hospital figure 2: basic principle of ct imaging procedure to construct the 3d image from 2d slices. 3.results and discussion the ct data are manipulated sequentially in the 2d slices and computationally reconstructed by adding each slice to 3d images. the radiant viewer software is a powerful tool for manipulating the hu values for each slice of the brain with a bullet inside. three modes of assessment have been used to study the embedded bullet (xue et al., 2012). these include imaging based on scout images, current properties, and hu values of the slices respectively. 3.1.scout images figure 3 illustrates the scout image of a head. the frontal and lateral scout images show in a and c respectively with a question mark to identify the location of the bullet from different directions. as mentioned earlier, the introduction part of the 2d and reconstructed 3d imaging is helpful to extract the measured current in ma and hu as a function of the number of slices from the differences in the intensity (i) the attenuation coefficients of the hard and soft brain tissues and a bullet. 3.2.image slices figure 4 displays the multiple discrete slices produced using the scout ct scan to define the starting and ending locations of the head. the 255 slice thicknesses were measured to be 0.625 mm generated from the diagnosis of the lodged bullet inside the skull. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 41 figure 3: the scout images of a head. figure 4: the 2d view of a slice image of the brain with different profiles. the 2d slices correspond to the gray levels of the images of the head due to x-ray source attenuation, reflection, scattering, and absorption. typically, the xray attenuation primarily is a function of x-ray energy and the density and composition of the brain tissues and the bullet. from the measured hu and current values, it is indicated that the gray level observed by the blue arrows on the 2d slice image of a brain with a different profile of ct imaging for a variation of a slice thickness in a range of 3 to 5 mm (osborne et al., 2016) and the interpretation based on michael et al., (2001). the assignment of each pixel based on the attenuation of water value on the scale reading is named hounsfield units (hu), after sir godfrey hounsfield (osborne et al., 2016). the different tissues are represented by arrows as displayed in figure 4. blue arrows indicate air, fat, fluid, and soft tissue of the brain described as the red dot lines (beam hardening artifact from the metal alloy in a lodged bullet). besides, the red arrows around the brain (bone of the skull around the brain) display the bright area indicated at the center of the slices by the green arrow that shows the expected location of the bullet in the brain. the ct helical slice above highlights the common anatomical structures which may help interpret the ct image of a shot brain. the hu value ranges of each area indicated using different arrows are labeled in table 1 based on the following equation: 100 tissue waterh   (3) where μwater and μtissue are the linear attenuation coefficient of water and the linear attenuation coefficient of tissue, respectively. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 42 table 1: hu values of areas indicated by different arrows and their profiles in figure 4 areas indicated by arrows hu values in (hu) remarks area indicated by red arrows 768 up to 1434 skull bone area indicated by blue arrows -15 up to 43 fluid and soft tissues area indicated by green arrow at the center 3071 bullet the amount of x-rays absorbed by the brain and the bullet was mapped as hu. the denser the tissue, the more x-rays were attenuated, and the higher the number of hu. water was always set to be 0 hu, while the air was −1000hu, and bones had values between several hundred to thousands of hu (bolliger et al., 2021). brain profiles were thus separated (air, soft tissues, fluids, bone, and bullets). the hu mapping was in the range of -1024 to +3071 for the ct scan. therefore, the maximum hu value was determined to be the bullet. the penetration level of the bullet was determined individually from the measured slice variation in both brightness and darkness, as shown in figure 5. it can be observed that the bright image with a higher density of the bullet has attenuation that only allows a small amount of radiation to pass through it. typically, the 108th and 124th slices with a dark area at the center of the 2d slice images have been observed in figure 5. however, the slices of the 109th to 123rd images have brighter areas at the center that indicates a lodged bullet in these slice numbers. therefore, the scan of the x-rays onto the metal bullet highly attenuated the incident source due to the heavier metallic atoms cu in the bullet. besides, the observation of a brain with a higher elemental combination of water of h and o atoms is observed as dark, there are heavy elements ca for the hard tissue and cu for a bullet with brighter figure print in the 2d slices each slice as a brighter area. 3.2.1. the current (in ma) through the slices figure 6 (a) displays the variation of the measured current vs. the number of slices set in the brain. the incident current was set at 10 ma and it produces 100 to 306 ma for each slice. it has been observed that the maximum current was recorded in the range of 300 to 306 ma for the slice numbers ranging from 100-120. it has been observed that such a high current for these slices is due to the presence of a bullet in the scanned slices that increases the conductivity of the measured slice and in turn, increases the current in these ranges of the measured slices. the variation of 255 slices with constant readings of the current was assessed on the slices between the 105th and 123rd. the brain profiles are composed of different materials. so cu in a bullet is a conductor with low resistivity. so, slices that had a bullet read the high current value. the current readings on the other slices were controlled by a high resistance of the brain profiles. the current readings from slices 105th up to 123rd were constant as a result of the presence of the bullet. a maximum of 306 ma current was measured from the 2d images of slices as the result of the higher conductivity of cu in a bullet however, the currents were normal for the 2d l slices that varied from 112 ma up to 304 ma. 3.2.2. the hounsfield value profiles of the slices studies prove that metal artifacts degrade the image qualities of bullets (makris et al., 2008). in contrast, the results of 2d image slices measured as hu were displayed in figures 6 (b) as the results of the different densities in a head such as air, water, soft tissue bone, hard tissue, and a bullet in terms of different hu values. medical scanners typically work in a range of –1024 hu to +3071 hu (osborne et al., 2016). it is labeled as the tissues greater than +100 hu in density appears pure white. there are standard labels in hu, where fat (-60 hu) and air (-1000hu) respectively form the examined patients. therefore, in this work, the hu value reading includes the maximum range of the medical scanner, the same +3071 hu (pure white), where a lodged bullet is identified. some slice profiles were assessed as cerebrospinal fluid (csf) (0 hu), skull bone (+100 hu), fat ( -50 hu), the air outside the patient (-1000 hu), and subdural hematoma (+60 hu) (gigantesco and giuliani, 2011). we discussed the image profiles of the slices based on the hu values by plotting the graph as shown in figure 6(b). this assessment included 22 slices. the hu numbers were closely spaced at the ranges of the soft tissue and below the level of water. spatially, slices from 111th up to 120th indicated the hu values around the proposed range. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 43 figure 5: systematic illustrations of slice images of the head (from 108th up to 124th). figure 6 (a): the tube current vs. number of slices; (b): the hu values as a function of the number of a slice with maxima and minima in hs. the center of the selected slices was evaluated as 3071 hu (pure white) and slices from 111th up to 121th had closely spaced hu readings below the level of water. most of the indicated areas of the slices indicate that the profile around the location of the proposed area might be soft tissues and fluid. it has been observed that the 3071 hu was at the center of the measured slices to the 109th to 123rd. now, the hu values through the brain images were compared with previous literature and discussed accordingly. it is believed that the csf hu values are in the range of 0 to 15 (nguyen et al., 2017). the hu ranges could vary from -1000 hu (air) up to +1000 hu (metal) (makris et al., 2008). the range of ct scan numbers was at hu value of up to 2000, and each scan represents a shade of gray with +1000 (white) and -100 (black) at either end of the spectrum. it has been indicated by (gruetzemacher and paradice, 2018), the metals' hu values are above 1000hu. however, the image of the bullet could read 3071 hu. ct scan 2d slices at different levels can determine the ventricular system with a central wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 44 image depicting the csf flows. it has a lateral ventricle and csf circulates into the subarachnoid space by exiting through the medial and lateral apertures (lind et al., 2019). 3.2.3. the location of a lodged bullet the internal structure of the brain around the location of a lodged bullet is indicated as the lateral cerebral vein, third ventricle, lateral ventricle, internal cerebral veins, midbrain, cerebral aqueduct, and thalamus. we investigated a lodged bullet at the left side of the third ventricle. the helical slice of the brain parts around the lodged bullet is shown in figure 7 (a). the 3d multiple planar reconstructions (mpr) technique was preferred to compare 2d and 3d images of the brain. the 3d mpr images of the brain were displayed and appropriate positions were adjusted by locating the x-y coordinate system at the location of the lodged bullet on slices. in this setup, the frontal and lateral 3d images and the selected slices were displayed at the same time. the comparison between 2d and 3d images helped guess and investigate the location of the lodged bullet inside the brain, as shown in figure 7 (b). we compared the lateral and frontal 3d images with 2d slices to gain evidence about the location of the bullet. the slices and the frontal 3d images indicated as the bullet was located in the left hemisphere of the brain. the lateral 3d image of the brain demonstrated how much the location was deep and how far the bullet was from the entry part at the frontal. the lengths were 11.28cm from the frontal, 79.2cm from the back, 6.96cm from the upper part of the brain, and as far as possible from the area of the mouth to the location of the lodged bullet respectively, as shown in figure 8 (a). the bullet is closely located on two major parts of the brain, namely, the hypothalamus, which is the central part of the brain, and the parietal, which is part of the cerebrum. the use of csf selection as a reference may serve as an adjunct for the evaluation of surgical lesions (kurihara et al., 2013). the csf refers to the space between the dura and the pia mater (papp et al., 2017). this space is filled with cerebrospinal fluid, which is a clear, very low-protein liquid similar to blood plasma but with a different electrolyte concentration (nguyen et al., 2017). this system is divided into two to four cavities that are connected by a series of holes. two ventricles are enclosed in the cerebral hemisphere called lateral ventricles which could be part of the location of the bullet. csf volume is the nearest and comparable to a lateral ventricle (osborne et al., 2016). the ct scan imaging was taken by the ccd to image the 2d slices, which were later constructed by the 3d images as shown in figure 8 (b). ct scan imaging changes the modern approach to determining patients’ practical observation of the brain that predetermines to acquire 0.5 to 0.625 mm thick tomographic images (ro et al., 2015). in this work, we set the slice thickness at 0.625 mm to include the region of interest to investigate the location of the bullet, as shown in the reconstructed 3d image shown in figure 8 (b). 3.3. three-dimensional (3d) images the 3d images of the head anatomy and the surrounding structures can be based on the interpretation of 2d slice summations (osborne et al., 2016). it is based on the generation of 2d images using radiant viewer software. such visualization can help to determine the small thickness in the measured multiple slices. it has been observed that a lodged bullet was on the 17 slices (ranging from 108th up to 124th) from the generated 3d image and is found to be 10.625 mm thick. the gray and dark colors help us to determine the hu for these measured slices. the upper gray level is measured at 1450 hu and the lower one at -900 hu. the darker colors range from -900 to 1450 hu. however, the upper gray levels are in the range of 1450 to 3071 hu for the brighter part touched by a bullet. figure 9 shows the frontal view of the head with an observation of the point link in the front skull and observed a lodged bullet from the reconstruction of the 255 slices. the bullet entered the skull at the front of the head and there was no indication of an exit wound, so the bullet may remain inside the head. here, the image has ww: 287, wl: 332, l-i: 0.00, s-i: 210 hu. this means that a total range of 287 hu is displayed, centered on a density of 332 hu. figure 9 (a) shows a 3d image generated from 255 slices of 2d images. the original 3d image was rotated at 210 … towards a vertical … with the best number of selected slices based on their physical profiles to map the skull. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 45 figure 7 (a): illustration of helical slices of brain parts around the location of a lodged bullet; (b): comparison of a lodged bullet location using 2d and 3d images. figure 8; (a) illustration of the location of the bullet from the 3d mpr method; (b) 3d image generated from 17 slices. the visualization of the internal parts of the head was shown from the deeper upper layer to the hypothalamus by rotating the 3d images at different directions and angles. this 3d image of the skull shown in figure 9 (b) was constructed from the first 200 slices out of 255 that generate a slice thickness of 0.625mm. our brain has complex structures and different functions. the images are displayed with the parameters such as wl at 287, ww at 332, lr at 00, si at 63.40, and roll at 21.80. this means that a total range of 287 hu is displayed, centered on a density of 332 hu. the 3d image was constructed from 200 slices and rotated at 70.00 towards a vertical circular trajectory downwards to observe the location of the lodged bullet inside the 3d image of the brain. this image could show the location of the bullet in the internal part of the brain, around the hypothalamic area. to be sure about the location of the lodged bullet in the hypothalamic part, the rotated images are shown in figure 10. to further observe the reconstructed 3d images at different angles upon the rotation of the x-rays, the source in the gantry is shown in figure 9 and figure 10. the visualization of the 3d images displayed taking bo as referenced is anticlockwise rotated by b1 by 700, b2 by 800, and b3 by 850 hu respectively. the findings of this study show that the bullet has traveled subcutaneously through the cerebrum passed through the lateral ventricle, and rested in the hypothalamus, near the cerebellum. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 46 figure 9: illustration of 3d ct image of skull very well demonstrating entry of the lodged bullet. figure 10: systematic visualizations of the location of the bullet in different viewing positions. 4. conclusion the clear observation of an embedded bullet can be easily identified by taking successive 2d slices by the ct scan and later reconstructing it into 3d images using radiant software. the x-ray source is scanning both the hard and soft tissues of the brain and an embedded bullet. the attenuation coefficients are different for these targets. it is based on the differences in the intensities for the measured values for the air, water, soft and hard tissue, and a bullet during the 2d slices images to measure the current in ma for each slice and mapped to the hu. typically, the hu value of the bullet was 3071h. the current readings from the slices were maximum on the lodged bullet due to the high density of the bullet made of cu and low current flows through normal slices made of h & o (slices without a bullet). the 3d images were rotated in different positions to visualize the bullet inside the brain images. correspondingly, findings from scout images, slices, and 3d images indicate that the bullet entered the frontal skull, and then passed toward the frontal cerebrum and other complex parts of the left hemisphere of the brain. finally, the lodged bullet is estimated to be in the ventricular system and the hypothalamus part of the brain image. an experienced physician could refer to this type of study during medical and surgical cases. atypical gunshot wounds, such as the case under investigation, an implications for multiple issues including delayed diagnostic tests, inaccurate radiological readings, and inappropriate medication management. ordering full head ct scans and making quick decisions in surgical and medical management are critical takeaways in providing quality care to patients with these injuries. acknowledgment the authors would like to thank bahir dar university, ethiopia, for providing a scholarship to the first author to complete his msc research in laser spectroscopy. wubante mehari wollelaw et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 47 we also extend our gratitude to felege hiwot specialized hospital, bahir dar, ethiopia, for providing us with the ct data. conflict of interest on behalf of all authors, the corresponding author declares that there is no conflict of interest in this study. authors’ contributions gaw has proposed the problem and gy has provided the ct images. wma and gaw have processed the ct images to convert the physical parameters and interpret the data. wmw has drafted the manuscript and gaw reviewed the manuscript. all of the writers have approved the manuscript in its current state. ethical statement/consent the authors declare that there is no human participant in the investigation of our paper. the experiment result was based on the ct imaging of the body of a 25-yearold person to look at the physics of a lodged bullet 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(2001). cone-beam reconstruction using filtered backprojection. in science and technology (issue 672). doi=10.1.1.134.5224 & amp;rep=rep1&amp;type=pdf. xue, z., antani, s. k., long, r. l., demner-fushman, d. and thoma, g. r. (2012). window classification of brain ct images in biomedical articles. amia annual symposium proceedings. 2012:1023–29. 102 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 prevalence of human immunodeficiency virus among tuberculosis patients visiting metehara sugar factory hospital, oromia regional state: a five-year retrospective study bizuayehu mekuria1 and daniel getahun debelo1* 1 adama science and technology university school of applied natural sciences: applied biology program. *corresponding author, e-mail: daniel.debelo@astu.edu.net abstract tuberculosis is the leading cause of death for hiv-infected patients, and hiv is the most important risk factor for developing active tb. the risk of death from tb is significantly higher in the hiv-infected population. the interaction between tb hiv co-infected person is bidirectional and synergistic: hiv infection predisposes to the development of active tb, and the course of hiv-related immunodeficiency is worsened by active tb infection. the aim of this five-year retrospective study was to assess the prevalence of tb hiv co-infections among patients who visited metehara sugar factory hospital (msfh) from march 2012 to april 2017. in total 1165 tb patients visited msfh from march 2012 to april 2017 and of these 1028 (88 %) who had a documented hiv test results were included in the study. data were collected from medical records of all tb patients who were on antituberculosis treatment during the aforementioned period. about 21 % of them were found hiv-positive. the percentage of tb/hiv co-infection was higher in females than males, single than married individuals, unemployed than employed and active working force than other age groups. the art coverage of the tb/hiv co-infected patients was 78 % which was lower than who target of 100 %. interventions to prevent hiv transmission among tb patients include counseling for patients and preventive intervention programs that attempt to change high-risk behavior. keywords: co-infection, hiv/aids, metehara, prevalence, retrospective, tuberculosis 1. introduction tuberculosis (tb) is a chronic infectious disease caused by mycobacterium tuberculosis which is also known as tubercle bacilli. tuberculosis is one of the major global health problems, which ranked as the second leading cause of death from an infectious disease bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 103 © adama science & technology university https://ejssd.astu.edu.et worldwide next to human immunodeficiency virus (hiv) that causes ill health among millions of people each year (who, 2012). human immunodeficiency virus (hiv) and tuberculosis are closely associated where hiv promotes the progression from latent infection to active disease and tb is the leading infectious killer of people living with hiv (lata et al., 2015). infection with hiv is an established risk factor for acquiring and developing infection with tuberculosis, and the recent increase in the worldwide prevalence of hiv infection has contributed to the rising global incidence of tb (abera et al., 2009). tuberculosis is one of the most common infections that threaten people living with hiv (plwhiv) in the developing world and together with hiv; tb is responsible for the deaths of over 4 million people annually (results canada, 2010). globally the most tb cases are in asia, the highest incidence rates are in sub-saharan africa where high rates of hiv and malnutrition weaken immune systems and accelerate the spread of the disease. consequently, the number of new tb cases in most african countries has more than quadrupled since 1990, with 2.8 million new tb cases and roughly 735 thousand deaths annually (fekadu et al., 2015). tuberculosis is a common opportunistic infection in sub-saharan africa. thus, the countries in the subregion continue taking the leading position in hiv/tb morbidity and mortality rate, where the tb epidemic was primarily driven by hiv infection (hailu and eshetu, 2013). tuberculosis has been recognized as a major public health problem for more than five bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 104 © adama science & technology university https://ejssd.astu.edu.et decades in ethiopia. ethiopia is one of the 22 high burden countries (hbcs) and tb remains one of the leading causes of mortality. according to the who (2014), the prevalence and incidence of all forms of tb are 211 and 224 per 100,000 of the population, respectively. about 13% of all new tb cases are also hiv co-infected. moreover, ethiopia is one of the high tb/hiv and multidrug resistant tb (mdr tb) burden countries. among tb patients with known hiv status, about 11% were hiv co-infected (mulugeta and alemu, 2016). according to the ethiopian ministry of health hospital statistics data, tuberculosis is the leading cause of morbidity, the third cause of hospital admission (after deliveries and malaria) and the second cause of death in ethiopia after malaria (efmoh, 2008). since 2002, ethiopia has been implementing the tb/hiv collaborative activities (efmoh, 2009). however, only few studies reported that hiv co-infection has been a major public health challenge among tb patients of the country (sebsibe and takele, 2013). assessment about hiv coinfection among tb patients might help to understand the spread of the co-infections and to monitor the performances of tb and hiv sustainable controlling and monitoring activities (who, 2012). understanding the predictors of tb/hiv co-infections in the local context is critical for ethiopia to improve co-management of tb/hiv co-infected patients (mitiku et al., 2016). the prevalence of tb infection is significantly associated with the incidence of hiv and vice versa across the areas in oromia region. assessment of the prevalence of tb among hiv patients and vice bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 105 © adama science & technology university https://ejssd.astu.edu.et versa is increasingly seen as important, as the hiv epidemic has continued to fuel the tb disease (abera et al., 2009). metahara sugar factory has a large number of workers and the workers have access to free treatment in the factory’s hospital. the hospital provides services for over 2800 patients per year. the prevalence of hiv among tb positive individuals at metehara sugar factory hospital has not been studied. knowledge of the prevalence of hiv positive cases among tb patients is important for better program planning hiv testing for all tb patients in order to design hiv/aids management program in an effort to stop the continued transmission of hiv within the community. therefore, this retrospective study was to investigate the prevalence and trends of hiv-positive individuals among tb patients (tb/hiv coinfections). 2. material and methods 2.1 description of the study area this study was carried out in metehara sugar factory (msf) in fentalle district, east shoa zone of oromia regional state. the factory is bounded by escarpments from east, west and south. it is located at 8o50'n latitude and 39o50'e longitude and the elevation is 950 m above sea level (fig. 1). it is found at a distance of 200 km southeast of addis ababa within upper awash valley, near the main road to harar. the area is typically characterized by semiarid climate with a mean relative humidity of 55.4 %, average annual rainfall of 543 mm, mean minimum and maximum temperatures of 17.2oc and 32oc, respectively (metehara sugar research metrological center, unpublished data). metehara sugar factory hospital provides services for over bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 106 © adama science & technology university https://ejssd.astu.edu.et 2800 patients per year. there were 4 doctors, 3 health officers, 30 nurses, 8 health extension workers,5 laboratory technicians, 1 radiologist, 2 hiv and anti hiv drug treatment nurses, 2 data encoders and case managers. the clinics provide basic health services entirely based on clinical symptoms within the respective villages and communities including from nearby afar and somali districts. however, laboratory based medical treatment for tb and hiv is provided only in the hospital. figure 1: map of the study area (source: ethio arc gis, 2017) 2.2 study population and study design the design of this study was a five-year retrospective descriptive survey of the prevalence of tb and tb/hiv co-infections among patients who visited msfh from march 2012 to april 2017. in total 1165 tb patients visited msfh and of these 1028 (88.2 %) who were registered and treated according to the clinical guidelines of the national tuberculosis and leprosy control program bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 107 © adama science & technology university https://ejssd.astu.edu.et (ntlcp) (efmoh, 2008) and had a documented hiv test results were included in the study. 2.3 variables the response variable for this study is the occurrence of tb/hiv co-infection. the predictor variables are socio-demographic characteristics (age, sex, occupation) and clinical related characteristics (art status, tb type, and treatment outcomes) of the patients. 2.4 data analysis collected data were checked for missing values, organized, coded, tabulated and then were analyzed using descriptive statistics with excel microsoft ware computer. descriptive statistics (frequencies and summary statistics (percentage) were used to describe patients' characteristics. 2.5 ethical consideration ethical clearance was obtained from health research ethical review committee of oromia regional health bureau. before conducting the study, the purpose and importance of the study was explained to the msf management, dots-hiv care unit officials and participants of the study. confidentiality and anonymity of the data from the hospital’s documents and interviewees were secured by using codes throughout the study. 3. results 3.1. socio-demographic characteristics of the total (1028) tb patients attended the hospital, male patients account for 56 % of the study subjects. most (60.4 %) of the patients were found in the age group 25 – 34 years and about 51 % (n = 521) were married, 32.5% were employed (table 1). 3.2 clinical characteristics of tb patients bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 108 © adama science & technology university https://ejssd.astu.edu.et type of tb, hiv status, art status, and treatment outcome of patients are depicted in table 2. about 80 % (n = 817) of the tb patients had pulmonary tb type and of the total patients about 66 % had smear negative pulmonary tb type. about 21 % (n = 211) of the total tb patients visited the hospital were found to be hivpositive, about 65 % completed treatment, 13.3 % (n = 137) were cured and 4.5 % (n = 46) of them died. about 79 % of the tb/hiv co-infected patients had been following anti-retroviral therapy (art). table 1. socio-demographic characteristics of tb patients at metehara sugar factory hospital from march 2012 to april 2017 (n =1028) variables number percentage (%) sex male female 575 453 55.9 44.1 age (years) 0-14 15 -24 25 34 35 44 45 54 >54 60 152 628 99 76 13 5.8 11.0 60.4 14.0 7.5 1.3 residence inside msf outside msf 382 646 38.1 61.9 occupational status employed housewife unemployed farmer/pastoralist others 334 166 156 78 294 32.5 16.1 15.2 7.6 28.6 marital status bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 109 © adama science & technology university https://ejssd.astu.edu.et note: others = students, merchants, preschool children, pensioners, commercial sex workers table 2: clinical characteristics of tb patients visited metehara sugar factory hospital from march 2012 to april 2017 (n = 1028) characteristics number percentage type of tb spptb snptb eptb 143 674 211 13.9 65.6 20.5 hiv status positive negative 218 810 21.2 78.8 art status (n = 218) pre art on art 48 170 22.0 78.0 treatment outcome completed cured transfer out defaulter failure dead treatment success 664 137 28 109 44 46 801 64.6 13.3 2.7 10.6 4.3 4.5 77.9 note: spptb = smear positive pulmonary tb; snptb = smear negative pulmonary tb; eptb = extra pulmonary tb; art = anti retroviral therapy married single widowed divorced children/undecided 521 299 39 22 147 50.7 29.1 3.8 2.1 14.3 bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 110 © adama science & technology university https://ejssd.astu.edu.et 3.3. prevalence of tb-hiv coinfection by age group of the study participants prevalence of tb/hiv coinfection of patients by age group and sex is shown in (table 3). about 21 % (n = 218) of the total tb patients visited the hospital were found to be hiv positive (tb/hiv co-infection). the percentage of female tb/hiv coinfected female patients was generally higher than that of males and the highest percentage (28.3 %) of hiv positive tb patients were in the age group 15 24 years both sexes considered together. 3.4 prevalence of tb/hiv coinfection by marital status and sex the percentage of hiv status of tb patients of unmarried males was about two-fold (26.0 %) than married ones (13.4 %) while that of single females was about 3.4 times than hiv positive married females. when hiv status of single and married tb patients of both sexes is seen, 35 % of single tb patients were hiv positive while only 15 % of the married tb patients were hiv positive (table 4). 3.5 prevalence of tb/hiv coinfection by occupational status of the patients most (51.3 %) of the 218 tb/hiv co-infected patients were unemployed and the percentage of females was higher than that of the males (table 5). 3.6 trend of tb/hiv co-infection among tb patients there was a slight decrease of tb/hiv trend from 2012 to 2015 but it increased from 2015 to 2017 fig. 2). bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 111 © adama science & technology university https://ejssd.astu.edu.et table 3: prevalence of tb/hiv co-infection of patients by age group and sex visited meteha sugar factory hospital from march 2012 to april 2017 (n = 1028) table 4: prevalence of hiv infection among tb patients by their marital status and sex at metehara sugar factory hospital from march 2012 to april 2017 (n = 218) male female both sexes age (years) number examined number positive (%) number examined number positive (%) number examined number positive (%) 0 -14 15 24 25 34 35 44 45 – 54 > 54 31 93 354 53 36 8 3 (10) 19 (20.4) 68 (19.2) 5 (9.4) 2 (5.6) 1(13) 29 59 274 46 40 5 6 (21) 24 (41) 69 (25.2) 15 (33) 6 (15) 0 (0) 60 152 628 99 76 13 9 (15) 43 (28.3) 137 (21.8) 20 (20.2) 8 (11) 1 (8) total 575 98 (17) 453 120 (26.5) 1028 218 (21.2) male female both sexes marital status number examined number positive (%) number examined number positive (%) number examined number positive (%) married single widowed divorced children 262 208 8 10 87 35 (13.4) 54 (26.0) 0 (0) 1 (10) 8 (9.2) 259 91 31 12 60 43 (16.6) 51 (56.0) 6 (19.4) 5 (41.7) 15 (25) 521 299 39 22 147 78 (15.0) 105 (35.1) 6 (15.4) 6 (27.3) 23 (15.6) total 575 98 (17) 453 120 (26.5) 1028 218 (21.2) bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 112 © adama science & technology university https://ejssd.astu.edu.et table 5: prevalence of hiv infection among tb patients by occupational status and sex at metehara sugar factory hospital from march 2012 to april 2017 (n = 1028) occupational status male female both sexes occupational status number examine d number positive (%) number examine d number positive (%) number examine d number positive (%) employed house wife unemployed farmer/pastoralist others 234 96 71 174 28 (12.0) 46 (48.0) 14 (20.0) 10 (6.0) 100 166 60 7 120 31 (31.0) 21 (15.0) 34 (57.0) 0 (0.0) 31 (26.0) 334 166 156 78 294 59 (18.0) 24 (14.5) 80 (51.3) 14 (18.0) 41 (14.0) total 575 98 (17) 453 120 (26.5) 1028 218 (21.2) note: others = students, merchants, preschool children, pensioners, commercial sex workers. fig. 2: trend of tb and tb-hiv co-infection at metehara sugar factory hospital from march 2012 to april 2017 bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 113 © adama science & technology university https://ejssd.astu.edu.et 3. discussion this study showed that tb occurs in all age groups. of the total (n = 1028) tb patients attended the hospital, male patients account for 56 % of the study subjects and this in line with derek et al. (2015) who reported that tuberculosis cases are more prevalent among men than women, and tb mainly affects adults in their productive years. of the different factors, gender difference is one of the risk factors which may indirectly influence the male-to-female ratio of tuberculosis. in high-burden countries, smoking is much more frequent in men than in women, and a correlative analysis of cigarette smoking, sex, and tuberculosis suggests that smoking might explain up to one-third of the gender bias observed in this setting. alcohol consumption is also a risk factor for tuberculosis, and the prevalence in low-income countries among men is much higher than that among women (watkins and plant, 2006). of the total tb patients, about 21 % (n = 218) of them were found hiv-positive. results of similar studies conducted on the hiv prevalence rate among tb patients show variations. the hiv prevalence rate in the present study is similar to some of these studies. in amhara regional state, tarekegn daniel et al. (2016) recorded about 20 % tb/hiv coinfection at metema hospital from 2009-2012 and amare (2015) reported about 22 % in a study conducted from 2009-2014 at fenote selam district hospital. however, adisu et al. (2016) reported a lower percentage of about 13 % in a study conducted from 2008 to 2013 at debretabor hospital, while a higher percentage (31 %) was reported by lengisa et al. (2015) and 44.8 % at debre markos referral hospital, bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 114 © adama science & technology university https://ejssd.astu.edu.et amhara regional state (ahmed et al., 2013). infection by m. tuberculosis exacerbates hiv infection. the incidence and mortality rates for new aids-defining opportunistic infections have been shown to be higher if individuals with hiv are co-infected with tb (pawlowski et al., 2012). generally, a relatively small proportion of people infected with m. tuberculosis will develop active tb disease. however, those with hiv have a much higher chance of developing the active disease. the burden of tb continues to increase due to poverty, population growth, and hiv/aids (derek et al., 2015). the results of this study showed that the proportion of tb/hiv co-infection was higher in females (26.5 %) than in males (17 %). some similar studies conducted in ethiopia showed even very high tb/hiv coinfection in females than in males. damtew et al. (2013) reported 37 % in bishoftu hospital and jemberu et al. (2017) reported 76.3 % of tb/hiv co-infection in females in gambella regional state hospital. higher infection in females is attributed to permanent immune suppression associated with pregnancy and more likely lowered immunity due to the stress as a result of their biological, economic and cultural roles as household care-givers (ahmed et al., 2013). women are more affected by hiv/aids than males because of their difference in their socio-economic, political, legal and cultural status, as well as biology (jackson, 2002). the higher prevalence of tb/hiv coinfection in female than males is expected due to the fact that hiv has more chance of transmission from males to females than from females to males. in line with this georgina et al. (2013) reported that the penile-vaginal bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 115 © adama science & technology university https://ejssd.astu.edu.et transmission by an infected individual in a single sexual exposure is as low as one in 1000 from female to male and as high as one in 300 from male to female (georgina et al., 2013). over 60 % (n = 628) of the tb patients were found within age group of 25 – 34 years and they constitute the highest (28 %) hiv positive, followed by 25 34 (21.8 %) and 35 44 (20.2 %) age groups in order. people in these age groups are more active for sexual activity and they are vulnerable to tb and hiv risk behaviors such as substance use and unprotected sexual practices than any other part of the population. the high co-infection prevalence among these age groups which comprises a large part of workforce and productive section of the society might face grave consequences of poverty that aggravate in acquiring the infections. these age groups, being parents of young children, could also be heavily contributing to spread of tb in the household (ehnri, 2011). similar studies at bishoftu hospital (damtew et al., 2013), metema hospital (tarekegn daniel et al., 2016) and debre markos referral hospital (amare, 2015) also reported highest hiv infected tb patients within age group of 25 34 years. the current study indicated that higher percentage (35 %) of unmarried tb patients was coinfected with hiv than married (15 %) tb patients. the percentage of single female (56 %) hiv-positive was over two-folds hivpositive single males (26 %). this may indicate that the single individuals practiced multiple sexual partners than the married ones which is one of the risk factors for contracting hiv. there was also variation in the prevalence of tb/hiv coinfection in relation to bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 116 © adama science & technology university https://ejssd.astu.edu.et occupational status. the rate of tb/hiv co-infection was higher among unemployed (51%) than employed (18 %) ones. high rates of unemployment lead to behaviors that increase the risks of tuberculosis and hiv infections such as alcohol consumption, smoking, intravenous drug use and unprotected sex (azukie et al., 2014; przybylski et al., 2014). sharma et al. (2005) also reported that tb/hiv co-infection is intricately linked to unemployment that resulted in poverty and homelessness which may result in malnutrition, drug side effect and low stamina among patients and may possibly lead to poor adherence, death or discontinuation of anti tb chemotherapy. mycobacterium tuberculosis– hiv co-infections pose particular diagnostic and therapeutic challenges and exert immense pressure on health care systems in african and asian countries with large populations of co-infected individuals (pawlowski et al., 2012). tuberculosis is the leading cause of death for hiv-infected patients, and hiv is the most important risk factor for developing active tb. the risk of death from tb is significantly higher in the hiv-infected population. the interaction between tb hiv co-infection is bidirectional and synergistic: hiv infection predisposes to the development of active tb, and the course of hiv-related immunodeficiency is worsened by active tb infection (amare, 2015). both tb and hiv have profound effects on the immune system, as they are capable of disarming the host’s immune responses. hiv co-infection is the most powerful known risk factor for progression of m. tuberculosis infection to activate the disease, increasing the risk of latent tb reactivation 20-fold. likewise, tb bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 117 © adama science & technology university https://ejssd.astu.edu.et has been reported to exacerbate hiv infection (pawlowski et al., 2012). most of the (79 %) tb/hiv co-infected patients had followed art. the art level shows variation in the country that 76.3 % was reported in northern amhara (daniel et al., 2015), 79.2 % in southwestern ethiopia (ephi, 2015), 54.6 % in addis ababa (mesfin, 2011), and 89.8 % in oromia (oromia region health bureau, 2015). in its national tb/hiv sentinel surveillance, the ethiopian public health institute (ephi) (2015) reported that at national level 70 % of tb/hiv coinfected patients have started or continued previously initiated art during the course of their tb treatment. according to the recent report art improves treatment outcome of tb/hiv co-infected individuals reduce early mortality from hiv/tb co-infection, and reduce tb transmission when art is initiated earlier in all individuals with tb and improved management of tb. hence programs need to provide due attention to the quality of tb/hiv care and put all tb/hiv coinfected patients on art treatment as part of the tb/hiv co-management and as per the 100 % recommendation in the national guideline (ephi, 2015). about 65 % of the tb patients completed treatment, 13 % cured and 4.5 % (n = 46) of the total patients died. treatment success defined as ‘treatment completed and cured’ after completion of dose regimen was 80 % and it is lower than the target set in ethiopia to achieve overall treatment success rate of 89 % (efmoh, 2013). the treatment success recorded in the current study shows variation from other similar studies conducted in different hospitals in the country. for instance, tigist and mulugeta bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 118 © adama science & technology university https://ejssd.astu.edu.et (2015) recorded 86 % treatment success at jimma university specialized hospital and omonada training health center, 87 % at debretabor hospital (adisu et al., 2016), 64 % at adama hospital, 29 % (fiseha et al., 2015), and 63.4 % at gambella regional hospital (getahun et al., 2015). this study revealed a constant trend in the percentage of tb/hiv co-infection from 2012 to 2014 but an increased trend from 2014 to 2016. earlier there was an increased awareness creation about hiv through health education and mass media on prevention and its control. however, currently less attention is given to the disease and thus it has been reviving. the present study found that treatment success (defined as treatment completed and cured) after completion of dose regimen was 80 % and it less than the target set in ethiopia to achieve overall treatment success rate of 89 % (efmoh, 2013). tigist and mulugeta (2015) reported 86 % treatment success at jimma university specialized hospital and omonada training health center, while adisu et al. (2016) reported 87.1 % at debretabor hospital. at adama hospital (64 %) (lenjisa et al., 2015) and mizan aman general hospital (29 %) (fiseha et al., 2015) reported lower rate of treatment success. 6. cnclusion the prevalence of tb/hiv co-infection in this study was high (21 %) and the percentage of coinfection is higher in females than males, single than married individuals, unemployed than employed and active working force than other age groups. the art coverage of the tb/hiv coinfected patients was 78 % which was lower than who target of 100 bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 119 © adama science & technology university https://ejssd.astu.edu.et %. the present study showed that there was an increase tb/hiv coinfection trend from 2014 to 2016. economic empowerment of females, awareness creation about prevention of tb and hiv/aids and job creation for jobless citizens, especially for those in the active working age can be used as intervention mechanisms of the diseases. acknowledgements the authors wish to thank the management and staff of hiv care units of metehara sugar factory hospital for providing necessary facilities used in carrying out this study. special thanks also go to oromia education bureau and adama science and technology university for funding the study. references abera bekele, kate flaming, zelalem habtamu and andrew fogarty (2009). the association of tb with hiv infection in oromia regional national state, ethiopia. ethiopian journal of health development. 23(1): 6367 adisu melese, belew zeleke and biniam ewnete (2016). treatment outcome and associated factors among tuberculosis patients in debre tabor hospital, northwest ethiopia. tuberculosis research and treatment. hindawi publishing corporation. 12(5): 1-8. http://dx.doi.org/10.1155/2016/13 54356 ahmed esmael, girma tesgaye, moges wubie and mengestu endris (2013).tuberculosis and human immune deficiency virus coinfection in debre markos referral hospital in northwest ethiopia. journal of aids and clinical research. 4 (12):263-268 amare desalegn (2015). tuberculosis and hiv coinfection among patients on tuberculosis treatment at fenote selam district hospital, amhara regional state, and northwest ethiopia. global journal of medical research. 15 (5):1-8 azuike, e. c., azuike, e. d., ohamaemae, m., obi, c., ilhogalu, d., odedibia,c., ebulue, c.,epundu, u., chikezie, n., aniagoboso, c. bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 120 © adama science & technology university https://ejssd.astu.edu.et and ezeneaku, c. 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(2006). does smoking explain bizuayehu m. & daniel g. ethiop. j. sci. sustain. dev., 5 (1), 2018 123 © adama science & technology university https://ejssd.astu.edu.et sex differences in the global tuberculosis epidemic? epidemiology and infection. 134: 333–339. who (world health organization) (2012). global tuberculosis report. geneva, switzerland who (world health organization) (2014). global updates on the health sector response to hiv. who, geneva, switzerland assessment of hepatitis b virus and associated risk factors among pregnant women attending antenatal care at arsi university asella referral and teaching hospital, ethiopia nigatu tumsa1, tulu degefu1, zerihun belay2 adama science and technology university school of applied natural sciences, applied biology program. abstract hepatitis b virus is a public health problem worldwide. vertical transmission from mother to baby is an important route of transmission for hepatitis b virus infection. consequently, screening pregnant women and realizing the sero-prevalence of hepatitis b virus during pregnancy is vital to prevent the infection of new born baby from positive mother. the objective of this study was to assess the sero-prevalence of hepatitis b virus among pregnant women and to identify potential risk factors associated with the infection. the study was conducted from january to may, 2016 using data from pregnant women attending the antenatal care unit of arsi university asella referral and teaching hospital, arsi zone,oromia regional state, ethiopia. blood samples were collected from 454 pregnant women and tested for hepatitis b surface antigen using rapid strip test which is a qualitative solid phase two site sandwich immunoassay. a pre-structured questionnaire was used to collect socio demographic data and to find out possible risk factors. the overall study subjects with hepatitis b surface antigen positive were 44(9.7%). most 301(66.3%) of study participants live in urban and 442(97.4%) were married. the socio-demographic status of the participants shows that high hepatitis b surface antigen positivity was among the urban 29(65.9%) and those who were house wife. all except the gestational age of 3 rd trimester (p<0.05) the participants demographic characteristic had no significant association with hepatitis b virus. none of the risk factors had statistically significant association with hepatitis b virus (p>0.05). it can be concluded that high prevalence of hepatitis b virus among pregnant women was found in this study as compared to the previous studies in different regions of ethiopia. this high prevalence indicates the importance of implementing preventive measures including vaccination to women in the child bearing age as they are at increased risk of acquiring hbv compared to the general population. key words: hepatitis b virus, pregnant women, prevalence, risk factors 1. introductio hepatitis b virus is the most serious types of viral hepatitis which can lead to chronic liver disease and put people at high risk of death from cirrhosis of the liver and liver cancer. globally, over 350 81 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 82 © adama science & technology university https://ejssd.astu.edu.et million people are affected with hepatitis b virus (hbv) infection and over 1 million die annually of hbv-related chronic liver disease (teresa and wright, 2006). although the major source of hbv is blood and blood products it is also found in semen, saliva, tears, breast milk, vaginal and menstrual secretions and amniotic fluid. transmission occurs through contaminated blood and blood components by transfusion, needle sharing, tattooing and through very close personal contact involving the exchange of semen, saliva and vaginal secretions and child birth (lavanchy, 2004). population at risk include health care personnel, intravenous drug users, hemophiliacs, infants born to hbsag positive mothers, renal dialysis patients, sexual partners of hbv carriers and individuals with multiple sexual partners (cdc, 2014). the major mode of transmission of hepatitis b virus is mother to child (teresa and wright, 2006). it has been reported that 10–30% of hbsag positive pregnant mother transmit the virus to their babies. however, mothers who are positive for both hbsag and hbeag have chance of transmitting hbv to their new born is 70-90 % (kwon and lee, 2011). up to 90% of the newborns born from these mothers go on to develop chronic hepatitis b caused by hbv if they do not receive hepatitis b virus immunoglubulin and hepatitis b vaccine at birth (apuzzia et al., 2012). hbv is the leading cause of chronic liver disease and liver related deaths worldwide with the majority of these causes occurring in africa and asia, where hbv prevalence is higher than 8 % (hoffmann and thio, 2007). the global prevalence of chronic hbv infection varies widely from high zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 83 © adama science & technology university https://ejssd.astu.edu.et (>8%) to intermediate (2-7%) and low < 2% (custer et al., 2004). the prevalence of hbv is estimated at 8 % in west africa and 5-7% in central eastern and southern africa (su, 2010). hepatitis b virus is endemic in africa next to asia, with a sero prevalence rate of between 8 and 20% (elizabeth and ramsey, 2011). in ethiopia, hepatitis b is endemic with an average prevalence of 10.8 %. however, it is likely to be underreported due to the lack of diagnostic facilities and appropriate surveillance systems (fassil shiferaw et al., 2016). in ethiopia studies have shown that wide geographic and socio economic variation in hepatitis b prevalence, ranging between 5.7 and 10.8 % (asfaw negero et al., 2011). the sero-prevalence of hbsag is found to be as high as 14.4% in blood donors (rahlenbeck et al., 1997). earlier hospital-based studies showed that hepatitis b accounts for 12 % of hospital admissions and 31 % of deaths in ethiopian hospitals (tsega, 2000). in a study that was done to define the mode of transmission of hbv infection in ethiopia showed that 5% of pregnant women were reported to be positive for hbsag (tsega et al., 1988). in another study which was done to determine the sero prevalence of hbsag and its risk factors among pregnant women in jimma southwestern ethiopia was 3.7% (mohammed awole and solomon gebresilasie, 2005). recent studies at public hospitals in ethiopia by tsegaye yohanes et al.(2016) and yeshi metaferia et al. (2016) showed that the prevalence of hbv infection among pregnant women was intermediate (2-7.8 %). apart from a dearth of information, concerning the prevalence of hbv infection zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 84 © adama science & technology university https://ejssd.astu.edu.et among pregnant women in ethiopia, the existing data are also differing from region to region. in addition, viral hepatitis screening services are not widely available except for the occasional mandatory medical checkups for work or travel purposes. the magnitude of the problem is so high that over 5.2% million people are estimated to be living with chronic hbv infection among the general population of ethiopia (ott et al., 2012). knowing the prevalence of hbv specifically during pregnancy is vital for the reason that major mode of transmission is prenatal and the best way of assessing the prevalence in general population is its prevalence in pregnant mothers. so screening of all pregnant mothers is critical to know the burden of the problem and to indicate the prevalence of hbv in ethiopia including the central regions of the country. by considering the existing scarcity of information about hbv infection in highly risk groups especially pregnant women the current study was conducted to determine the prevalence of hbv among pregnant women and risk factors associated with hepatitis b infection among pregnant women attending antenatal care at arsi university, asella referral and teaching hospital, central ethiopia. 2. materials and methods 2.1. study area the research was conducted at arsi university asella referral and teaching hospital, ethiopia. asella is found in oromia regional state, central ethiopia, at a distance of 178 km southeast of capital city addis ababa. according to csa (2007), asella town has a total population of 74,268 of whom 37,337 are male and 36,931 are females. the hospital is a referral and teaching zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 85 © adama science & technology university https://ejssd.astu.edu.et hospital serving people coming from all over 22 weredas in arsi zone. it gives antenatal care service for more than average 20 pregnant women daily. the hospital is with two laboratory rooms, one for mch and the other for the other patients attending the hospital. 2.2. study population and design a cross sectional hospital based study was conducted among pregnant women attending antenatal care at arsi university, asella referral and teaching hospital and voluntary to participate in the study by giving blood sample for screening hbv infection and to respond questionnaires during study period. sampling size was calculated with single proportion formula by taking hepatitis b surface antigen prevalence from other studies conducted among pregnant women 4.5% (kothari,2004) 2% error of margin and 10 % non -response rate (𝑍𝛼/2)2𝑃(1−𝑃) n= , 𝑑2 (where n=sample size; p = proportion of hbsag prevalence reported in similar study noted above (4.5%); d=2% error of margin; z α/2 =standard normal probability for 95% ci (1.96). 2.3. data collection and laboratory investigation a pre-tested structured questionnaire was delivered to volunteer pregnant women to obtain socio-demographic information including maternal age, gestation age, occupation, educational status, living area and other information on risk factors for transmission of hbv including a history of previous blood transfusion, place of previous birth, any surgical procedure, tattooing, and hospital admission by data collectors. the questionnaires were first prepared in english then translated into zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 86 © adama science & technology university https://ejssd.astu.edu.et afan oromo and amharic. after completion of the questionnaire, about 5ml of blood sample was aseptically collected by venipuncture from each participant into sterile plane bottle. the blood samples were left to form clots at room temperature, after which they were centrifuged for 10 minutes at 200 revolutions per minute (rpm) to separate serum or plasma from clot. sample testing was done using rapid strip test which is one step test that utilizes the principle of rapid chromatographic immunoassay for the qualitative detection of hepatitis b surface antigen in serum or plasma (blumberg, 1971). the separated serum was allowed to equilibrate to room temperature (15-300c).to perform the laboratory test the foil pouch was opened and remove the strip. the strip was deepened in to the serum for at least 5 seconds until it was thoroughly wet and reaches the level indicated by the arrows on the strip. the strip was removed from the specimens and placed on a flat dry surface until the red lines appeared. the result was read in 15 minutes. interpretation of the result was made as follows. positive: two distinct red lines appear, one line should be in the control region(c) and another line should be in the test region (t). negative: one red line appears in the control region (c).no apparent red or pink line appears in the test region (t). invalid: control lines failed to appear due to insufficient specimen volume or incorrect procedural techniques. in that case the procedure was repeated with a new test strip. 2.4 data analysis the sero-prevalence of hbsag was expressed in percentages in the study group and results were presented in tables. data was entered and analyzed using the zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 87 © adama science & technology university https://ejssd.astu.edu.et statistical software spss version 21. chi-square test and bivariate logistic regression analysis were used to determine the association between dependent variables and the independent variables. the result was considered statistically significant at p<03. 3. results 3.1 the socio-demographic characteristics of the participants this study included 454 pregnant women attending the antenatal care unit of arsi university asella referral and teaching hospital during the period of january, 2016 to may, 2016. out of the total participants, 197 (43.4%) were in the age group 23-27, followed by 125 (27.5%) in the age group 28-32, 96 (21.16%) in the age group 18-22, 29 (6.4%) in the age group 33-37 and 7 (1.5%) were in the age group 38 42(table.1). most of the study subjects were from urban 301(66.3%) and almost near to the total number of the study participants were married 443 (97.5%). the majority of the study participants were house wives 77(17.0%) and about half of these women had an education level of less than secondary school (table 1). 3.2 the risk factors of hbv infection the risk factors included in this study were history of blood transfusion, hospital admission, surgical procedure, multiple sexual practice, female genital mutilation and body tattooing. most of the participants 408(89.9%) had no history of blood transfusion. of the total, 333(73.3%) were not admitted in hospital. of the total, only 36(7.9%) of the pregnant women had history of surgical procedure. but majority of the participants 439(96.7%) had no history of zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 88 © adama science & technology university https://ejssd.astu.edu.et multiple sexual practice. similarly, 282(62.1%) of the pregnant women had no genital mutilation and only 25(5.5%) had tattoo on their body (table 2). table 1. the socio-demographic characteristics of pregnant women attending the antenatal unit at arsi university asella referral and teaching hospital, 2016. socio-demographic characteristics frequency percentage (%) age group 18-22 96 21.1 23-27 197 43.4 28-32 125 27.5 33-37 29 6.4 38-42 7 1.5 resident urban 301 66.3 rural 153 33.7 marital status single 11 2.4 married 443 97.5 educational status illiterate 71 15.6 1-8 157 34.6 9-12 142 31.3 diploma 65 14.3 degree and above 19 4.2 gestational age 1st trimester 46 10.1 2nd trimester 104 22.9 3rd trimester 304 67.0 abortion status yes 87 19.2 zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 89 © adama science & technology university https://ejssd.astu.edu.et no 367 80.8 place of previous delivery no birth 197 43.4 home 80 17.6 health institution 177 39 screened for hbv yes 274 60.4 no 180 39.6 vaccination for hbv yes 19 4.2 no 435 5.8 total=454(100%) under each variable table 2. the risk factors characteristics of the participant women attending the antenatal unit at arsi university asella referral and teaching hospital, 2016 variables frequency percent history of blood transfusion yes 46 10.1 no 408 89.9 hospital admission yes 121 26.7 no 333 73.3 surgical procedure yes 36 7.9 no 418 92.1 multiple sexual activity yes 15 3.3 no 439 96.7 body tattooing yes 25 5.5 no 429 94.5 zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 90 © adama science & technology university https://ejssd.astu.edu.et female genital mutilation yes 172 37.9 no 282 62.1 3.3. sero-prevalence of hbv in pregnant women by socio demographic characteristics among 454 pregnant women tested for hbsag, 44(9.7%) were positive for hbsag (table 3). the sero-prevalence of hbsag in relation to age showed that the highest prevalence of hbsag 15(34.1%) were in the age group of 23-27, followed by 14 (31.8%) in the age group of 28-32, and 12 (27.3%) was in the age group of 18-22. majority of pregnant women 29(65.9%) positive for hbv were in urban and all of 44(100%) positive mothers were married. high number of hbsag positive 27(61.3%) were in elementary and high school educated. with regard to occupation hbsag positivity was highest 29 (65.9%) among house wife and most 24(54.5%) of hbsag positive mothers were on 3rd trimester followed by 12 (27.3%) on 2nd trimester (table 3). 3.4. the association between prevalence and risk factors of hepatitis b virus the expected risk factors associated with exposure to hbsag were determined by comparing the significant association (p<0.05) of hbsag detection for study participant as shown in table (4). none of the risk factors had been found to be associated with hbsag sero positivity (p>0.05). however, almost most of the study participants were exposed to at least one hbv infection risk factors. among 454 pregnant women tested 172 (37.9%) had history of female genital zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 91 © adama science & technology university https://ejssd.astu.edu.et mutilation of these 20(45.5%) were positive for hbsag which was the highest prevalence among risk factors. out of 121(26.6%) who were admitted to hospital 14 (31.8%) were positive for hbv. a total of 46(10.1%) had history of blood transfusion of these 3(6.8%) were positive for hbsag, 36 (7.9%) had surgical procedure of these only 2(4 .5%) were positive for hbsag. 15(3.3%) had multiple sexual activity out of these only 3(6.8%) were positive. pregnant women who had body tattoo were 25(5.5%) among these only 2(4.5%) were positive for hepatitis b surface antigen. table 3. sero-prevalence of hepatitis b virus (hbsag) by socio-demographic characteristics of the participant women attending the antenatal unit at arsi university asella referral and teaching hospital, 2016. variables bsag positivhbsag (+) freq. freq. %) hbsag (-) freq. (%) x2 p value age 18-22 12 27.3 84 20.5 34.1 23-27 15 182 44.4 2.589 28-32 14 31.8 111 27.1 0.912 33-37 2 4.5 27 6.6 38-42 1 2.3 6 1.5 resident urban 29 65.9 272 66.3 0.003 0.433 rural 15 34.1 138 33.7 marital status single 0 0 11 2.7 1.323 married 44 100 398 97.1 in relationsh ip 0.998 0 0 1 0.24 zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 92 © adama science & technology university https://ejssd.astu.edu.et educatio nal status illiterate 1-8 9-12 diploma degree & above occupati on employed house wife daily labor student self employer gestation al age 1st trimester 2nd trimester 3rd trimester abortion status 3.829 4.643 0.132 0.011 3.390 0.119 11 25 60 14.6 14 31.8 143 34.9 13 29.5 129 31.5 4 9.1 61 14.9 2 4.5 17 4.1 7 15.9 70 17.1 29 2 65.9 4.5 281 11 68.5 2.7 0.678 0.806 1 2.3 8 2 5 11.4 40 9.8 8 18.2 38 9.3 12 27.3 92 22.4 24 54.5 280 68.3 yes 13 29.5 74 18.1 no place of 31 70.5 336 82 previous zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 93 © adama science & technology university https://ejssd.astu.edu.et birth no birth 20 45.5 177 43.2 home 13 29.5 67 16.3 hospital 11 25 166 40.5 screened for hbv 6.424 0.1 37 yes 22 50 252 61.5 no 22 50 158 38.8 vaccinati on for hbv yes 0 0 19 4.6 no 44 100 391 95.4 2.182 0.101 2.128 0.998 *total sample=454(100%), positive=44(100) negative=410(100) under each variables table 4. bivarate assessment of risk factors for hepatitis b virus (hbsag) positivity variables frequency (%) hbsag. +ve (%) x2 p-value history of blood transfusion 46(10.1) 3(6.8) 0.588 0.156 history of multiple sexual activity 15 (3.3) 3(6.8) 1.665 0.998 surgical procedure 36(7.9) 2(4.5) 0.764 0.188 hospitalization 121(26.7) 14(31.8) 0.665 0.063 female genital mutilation 172(37.9) 20(45.5) 1.186 0.243 body tattooing 25(5.5) 2(4.5) 10.160 0.330 no risk factor 40(8.8) 0(0) total 454(100) 44(100%) zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 94 © adama science & technology university https://ejssd.astu.edu.et 4. discussion in this study the overall prevalence of hbsag in pregnant women was 9.7%. according to hbv prevalence classification of who (2011), the finding of this study has showed high endemicity of hbv infection (≥8%) among tested pregnant women. this investigation implies that the pregnant women are at high risk for transmission of the disease. the seroprevalence found in this study was comparable with the findings of previous studies in sub-saharan countries such as 10.2% in cameron (noubiap et al., 2015), 8.2% in northeast nigeria (olokoba et al., 2011) and in mali 8% (maclean et al., 2012). contrary to these, it was higher than the study conducted in different regions of ethiopia in addis ababa 3% (dessie tegegne et al., 2014), in jimma , southwest ethiopia 3.7% (mohammed awole and solomon gebresilasie, 2005), in bahir-dar , northwest ethiopia 3.8% (yohanis zenebe et al., 2014), arba minch general hospital 4.3% (tsegaye yohanes et al.,2015) and in addis abeba in three teaching hospitals 4.5% (sisay kirba, 2014). however, it was lower than the study reported in university of benin, nigeria in which the prevalence of hbv infection among pregnant women was 12.5% (ugbebor et al., 2011), in zaria 18.2% (luka et al., 2008), in makurdi, nigeria 11% (mbaawuage, 2008) and in taiwan 15.5% (lin, 2008). the difference in prevalence might be due to geographic variations and different sample populations (vazquez-martinez et al., 2003), difference in socioeconomic status and traditional practices. in developed nation where regular screening and vaccination of hbv is provided for pregnant https://www.ncbi.nlm.nih.gov/pubmed/?term=tegegne%20d%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=24731794 zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 95 © adama science & technology university https://ejssd.astu.edu.et women low prevalence rate (<2%) was reported (0.14 %-0.97%) in usa (euler et al., 2003), (1.65%) in mexico (vazquez –martinez, 2003) and (1.6%) in saudi arabia (alrowaily et al., 2008). a study conducted by ding et al. (2013) indicates that the prevalence of hbsag among pregnant women in shenyang, china was lower than the overall prevalence in china because the transmission from mother to child can be prevented by administration of immunoprophylaxis with hbig and hbv vaccine. the present study also revealed that the socio demographic characteristics of the pregnant women did not show significance association with the prevalence of hbv infection except the gestational age (p= 0.011). the highest sero prevalence of hbv infection was found in those pregnant women at the third trimester as compared to first and second trimesters. this was similar with other studies conducted elsewhere in ethiopia (zelalem desalegn et al. 2016; yeshi metaferia et al., 2016). in this study, age was found to have no significant associations with hbv infection. however, other studies showed higher prevalence among women between the ages of 23 to 32 (tsegaye yohanes et al., 2016; nyamusi et al., 2017). this is expected because majority of women in the child bearing age are in their twenties. moreover, though not significant higher prevalence of hbsag 29(65.9%) was reported from urban area which is similar to in sudan (abdallah et al., 2011) and in rwanda (nyamusi et al., 2017). however, contrary to this other study in southern ethiopia (yeshi metaferia et al., 2016) showed higher prevalence of hbsag among pregnant mothers from zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 96 © adama science & technology university https://ejssd.astu.edu.et rural area than the urban counterparts. this study revealed that none of the expected risk factors were significantly associated with sero positivity for hbsag (table 4). however the female genital mutilation was the highest in the percentage of the prevalence of hbsag 20 (45.5%) which indicates that traditional practicing of unsterilized instruments for genital mutilation may increase the risks of infection than other risk factors. elsewhere in the previous reports, other factors such as blood transfusion, body tattooing, multiple sexual activity and surgery were potential risk factors for hbv infection (yohanis zenebe et al.,2014: yeshi metaferia et al., 2016). this variation might be attributing to cultural, being aware on prevention and transmission, educational and behavioral differences for the risk factors of hbv infection. 5. conclusion in conclusion, in this study, the prevalence of hbsag among pregnant mothers attending arsi university asella teaching hospital was high according to who criteria. all of the demographic characteristics of the participants had no significant association with hbv infection except for the gestational age which shows the significant prevalence in the 3rd trimester compared to other factors. the high prevalence of hbsag among pregnant women in this study indicates the importance of implementing preventive measures, including vaccination to women in the child bearing age as they are at increased risk of acquiring hbv compared to the general population. zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 97 © adama science & technology university https://ejssd.astu.edu.et acknowledgements we are very grateful to the pregnant women who showed willingness to participate in the study and to the staff of arsi university asella referral and teaching hospital. references abdallah, t.m., mohamed, m.h., and ali, a.a. 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(2003): seroprevalence of hepatitis in pregnant women in mexico. salud pública de méxico, 45(3): 165-70. who (world health organization), (2011): hepatitis b world health organization. www.who int/ entity/ csr /disease/ hepatitis b whocdscrlyo 2002 -2 pdf. accesse 19th 2011. yeshi metaferia, walelign dessie, ibrahim ali and anteneh amsalu, (2016): seroprevalence and associated risk factors of hepatitis b virus among pregnant women in southern ethiopia: a hospital-based cross-sectional https://www.ncbi.nlm.nih.gov/pubmed/?term=tsega%20e%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=11144885 http://europepmc.org/search?query=journal%3a%22ethiop%2bmed%2bj%22&amp;page=1&amp;restrict=all%2bresults https://www.ncbi.nlm.nih.gov/pubmed/?term=tsega%20e%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=tsega%20m%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=mengesha%20b%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=mengesha%20b%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=nordenfelt%20e%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=hansson%20bg%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=hansson%20bg%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/?term=lindberg%20j%5bauthor%5d&amp;cauthor=true&amp;cauthor_uid=2976060 https://www.ncbi.nlm.nih.gov/pubmed/2976060 https://www.ncbi.nlm.nih.gov/pubmed/2976060 zerihun belay ethiop. j. sci. sustain. dev., 5 (1), 2018 101 © adama science & technology university https://ejssd.astu.edu.et study. epidemiology and health, 38: 7. yohanis zenebe, wandemagegn mulu, mulat yimer and bayeh abera (2014): seroprevalence and risk factors of hepatitis b virus and human immune defiency virus infection among pregnant women in bahir dar city ,north west ethiopia ;a cross sectional study .bmc infection and diseases , 14(118): 2-7. zelalem desalegn, adane mihret, habtamu bedimo beyene, mengistu yilma, yimer seid, wondmagegn tamiru, abebe ejigu, wudma alemu, abdisa boka and yehenew a. ebstie, (2016): survey of hepatitis b virus infection and risk factors among pregnant women at public hospital in ethiopia. international journal of biomedical research, 7(7): 450-456. 49 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper assessment of soil acidity and determination of lime requirement under different land uses in gumer district, southern ethiopia aliyu nesru1, achalu chimdi2, wondwosen tena3 1department of natural resources management, wolkite university, wolkite, ethiopia 2department of natural resource management, ambo university, ambo, ethiopia 3department of plant biology and biodiversity management, addis ababa university, addis ababa, ethiopia article info abstract article history: received 02 june 2022 received in revised form 18 november 2022 accepted 28 december 2022 the study was initiated to assess the level of soil acidity and lime requirement of four types of land uses (forest lands, grazing lands, cultivated lands, and eucalyptus tree plantation) and in replications from 0-20 cm soil depth. lime requirement was evaluated by exchangeable acidity and buffer solution methods. the data were analyzed by sas software, version 9.1. the study revealed that soils of cultivated and eucalyptus lands were very strongly acidic with mean of ph 4.8 and 5.0, whereas soils of grazing lands were strongly acidic with ph 5.5 and forest lands were moderately acidic with ph 5.7and 5.6 in both kebeles, respectively. meaningfully higher ph, om, tn, cec, exchangeable ca2+, and mg2+ were noted under forest lands as compared to the remaining land uses. however, meaningfully lower exchangeable acidity (ea) (1.06) and percentage acid saturation (pas) (5.18) were obtained in the forest lands than in the other land uses. significantly higher available p (2.54) was noted in the grazing land, followed by natural forest (1.77) land for berchernamocheya kebele, and higher available p was recorded under forest (2.50), followed by grazing land (2.37) for badnayegor kebele. significantly higher exchangeable k+ (1.29) and na+ (0.63) were observed in grazing land for badnayegor and berchernamocheya kebeles, respectively. the results of the lime requirement revealed that using the smp buffer solution method recorded 4.1-11.3 t/ha while using the exchangeable acidity method recorded 1.3-6.7 t/ha across the land uses for both kebeles. based on lime requirement determination methods, the amount of lime required highly varies among the land uses. the investigation showed that soil acidification is a serious problem in the study areas. thus, integrated land management needs to be practiced to overcome the problem of soil acidification and achieve sustainable agricultural production. keywords: land uses, lime requirement, soil acidity, soil properties, 1. introduction different land uses have various influences on soil deprivation on physicochemical properties (alelgn et al., 2021). assessment of soil quality indicators related to updated soil nutrient management practices is a suitable and primary indicator for sustainable agricultural land management (agbede, 2010; wang et al., 2010). such an assessment is used to understand corresponding author, e-mail: achaluchimdi@yahoo.com https://doi.org/10.20372/ejssdastu:v10.i1.2023.512 nutrient availability in soils. this knowledge can determine whether definite land uses are suitable for a given crop production system or not (wang et al., 2010). soil acidification is one of the fundamental chemical soil degradation problems limiting crop production and productivity in various parts of ethiopian highlands receiving high rainfall. the problem is also intensifying http://www.ejssd.astu.edu/ aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 50 in scope in most other ethiopian highlands, severely limiting crop production. for instance, in most barley, wheat, and faba bean growing areas of central and southern ethiopian highlands, agriculturalists have shifted to the production of acid-tolerant crops such as oats rather than acid-sensitive crops (wassie & boke, 2009; chimdi et al., 2012). challenges of soil acidification are mainly related to acid soil forming exchangeable aluminum (al3+) and exchangeable hydrogen (h+) and low availability of exchangeable basic cations. in acidic soil areas, exchangeable bases are easily removed through leaching and crop harvest (lenka et al., 2007; ermias et al., 2016). most of the ethiopian agricultural lands are affected by soil acidity and need appropriate amendment options including the application of liming material (birhanu et al., 2014; behera & shukla, 2015; bikila, 2019; mesfin et al., 2020). therefore, soil acidity is a serious concern calling for urgent consideration in most ethiopian highlands because of its impact on crop yields and soil fertility (chimdi et al., 2012; chimdi, 2014; kidanu & chimdi, 2018). even though soil acidity is recognized as an issue requiring urgent thoughtfulness in most ethiopian highlands, there is very limited information about the impact of land uses on the level of acidity and the magnitude of lime required to neutralize soil acidity and other acidity-associated soil physicochemical properties in gumer district. hence, the current research was initiated with the specific objective of assessing the degree of soil acidification and the level of lime needed to reclaim acidification under three land uses. 2. materials and methods 2.1.description of the study area the current investigation was undertaken in the gumer district of gurage zone, southern nationsnationalities, and people's regional state. the district is located 220 kilometers south of addis ababa on the main road to jimma, and 65 kilometers from wolkite, the capital of gurage zone (figure 1). it is found at 7º8′4″8o00′6″ latitude north and 37º8′9″38º2′00″ longitudes east. 2.1.1. topography and climate. topographically, the study district is composed of a flat plain (7%), and average slope (35%), and the extremely sloppy area covers 58% of the district. the altitude of the study site ranges from 2,600 to 3,170 masl and falls in the highland agro-climatic zone. according to ethiopian meteorological agency, the average annual rainfall of the area is 10011400 mm, with a bimodal rainfall pattern. the main rainy season ranges from june to september and the short rain period covers the months from february to april. the genuine rainy season ranges from june to the end of september. the mean maximum and minimum annual temperature of the study area varies between 17.5oc and 10.1oc, respectively (national meteorological agency, 2017). 2.1.2. farming system and soil types agriculture is the main source of revenue in the gumer district. the district comprises a largely diversified farming system that includes field crop production (which includes enset, eucalyptus tree, barley, bean, pea, and wheat as the main economic activities and livestock rearing (cattle, goat and sheep) as the second most important economic activity in the district. the major vegetables grown in the area are potato, cabbage, garlic, onion, endive, beetroot, carrot, and many more. the data obtained from fao (1991) shows the soil type in the district is mainly cambisols and plinthosols. 2.1.3. site selection and soil sampling technique purposive field surveillance and reconnaissance survey and selection techniques were undertaken before selecting the study site. among the sixteen districts of gurage zone, gumer district was purposively selected; this was because of susceptibility to land degradation and soil acidity in most of the highland areas of the district. the presence of representative land uses and topographical situation were the criteria used to identify the study site. accordingly, cultivated land, eucalyptus plantation land, natural forest land, and grazing land were selected from brchernamocheya and badnayegor kebeles and considered for the study. a soil sample was collected from each land use with a random and uniform collection of representative soils. replication of nearly 1 kg representative soil from the top surface (0-20 cm) of every land use was collected, dried, sieved, prepared, labeled, and transported for laboratory analysis. by doing so, 24 composite soil samples were collected from the selected land uses of the two kebeles. aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 51 figure 1: location map of the study area additionally, for the determination of soil bulk density, undisturbed 24 soil samples were taken from each land use in replication using a core sampler. conversely, soil samples were grounded to pass a 0.5mm size sieve for analysis of total n and oc. a randomized complete block design was conducted with three replications. 2.2. soil laboratory analysis the analysis of soil samples was carried out at wolkite soil laboratory center using regular laboratory procedures and methods for the determination of lime requirement. 2.2.1. evaluation of selected soil parameters soil texture was measured through the bouyoucos hydrometer method, which can be written (day (1965). soil bulk density was determined using the core sampler method. an average value of soil particle density of 2.65g cm-3 was considered for the calculation of total soil porosity. total porosity was estimated from bulk and particle densities as described by brady and weil (2016). soil ph was measured using a digital ph meter as a suspension of a 1:2.5 soil-water ratio (van reeuwijk, 2002). cation exchange capacity (cec) and exchangeable bases were extracted by 1m of nh4coch3 at (ph 7) as described by chapman (1965). the extracts of exchangeable ca2+ and mg2+ as well as na+ and k+ were measured using atomic absorption spectrophotometer flame photometer, respectively (chapman, 1965). the cec was determined from the displaced nh4 + through distillation followed by titration. exchangeable acid was determined by saturating the soil with 1n kcl solution and titrating it with naoh as described by mclean (1965). a neutral 1n kcl solution was used to leach exchangeable h+ and al3+ ions from the soil. after the determination of organic carbon, using wet digestion, soil organic matter was calculated from organic carbon (om=1.724 * %oc)as described by walkley & black (1934). soil total n was measured using the kjeldahl digestion procedure as designated by jackson (1958). the available p was determined by using the olsen method (olsen et al., 1954). soil percent base saturation (pbs) was calculated by taking the ratio of the sum of basic exchangeable cations (ca2+, mg2+, na+, and k+) ions to cec as a percentage. effective cec, pbs, and pas were calculated as follows: (1) 100* )(. cec ionsnakmgcabaseex pbs   aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 52 𝐸𝐶𝐸𝐶 = (𝐸𝑥. 𝑏𝑎𝑠𝑒𝑠(𝐶𝑎2+ + 𝑀𝑔2+ + 𝐾+ + 𝑁𝑎+) + 𝐸𝑥. 𝐴 (2) 100* . ecec acidityex pas  (3) 𝐸𝑥. 𝐴 = (ex. h+ + ex. al3+) (4) 2.2.2. methods used for lime requirement (lr) determination the methods that were used for the lime requirement determination for this research were exchangeable acidity with the unbuffered neutral salt solution method and the smp buffer solutions method. shoemaker, mclean, and pratt buffer for the lime requirement was employed using the buffer solutions method as developed by shoemaker, mclean, and pratt (smp) buffer solution (shoemaker et al., 1961). the smp buffer method measures the change in ph of a buffer triggered by soil acidity and alteration in buffer ph is a quantity of lime requirement of soil. after determination of the prepared buffer ph, soil samples were determined by using smp buffer solutions, at wolkite soil testing center, and the lime requirement was assessed by referring to a published table, linking buffer ph to aimed ph. 2.2.3. extraction of exchange acidity method exchange acid is the total exchangeable h+ and al3+ adsorbed on a soil exchange complex. the exchangeable acidity above ph 5.5 is very low or even absent since exchangeable acidity is present appreciably only at ph < 5.5. the soil exchangeable acidity was determined as designated by shoemaker et al. (1961). the mathematical model developed by kamprath (1984) was used to calculate lr determination. 𝐿𝑅, 𝐶𝑎𝐶𝑂3 ( 𝑘𝑔 ℎ𝑎 ) = 𝑐𝑚𝑜𝑙𝐸𝐴 𝐾𝑔𝑠𝑜𝑖𝑙 ∗ 0.2𝑚 ∗ 1000𝑚2 ∗ 𝐵𝐷 ( 𝑚𝑔 𝑚3 ) ∗ 100 200 (5) where: ea = exchangeable acidity and bd = bulk density 2.2.4. data analysis: data generated from laboratory analysis were subjected to analysis of variance (anova) using statistical analysis system (1999) version 9.1. 3. results and discussion 3.1.soil physical properties the analytical result showed that all soil textures changed highly significantly (p < 0.01) in badnayegor and berchernamocheya kebeles except the silt portion in badnayegor kebele, which significantly (p < 0.05) varied between land uses (table 1). in all land uses of berchernamocheya kebele, a sand portion was high (52.3332.33%) tailed by a silt portion (39.33 24.67%) and a clay portion (28.8316.67%). however, in badnayegor kebele, sand, silt, and clay fractions ranged from 55.67 41.0%, 36.33 to 26.0%, and 30.0% 15.33% respectively, in all land uses (table 1). relatively, the sand fraction was the largest proportion in all land uses of the two kebeles. the current finding is corroborated by the findings of abbasi et al., (2007) and tessema (2008). the authors state that the disparity of soil texture between land uses implies the effects of land uses on soil properties triggered by different utilization and management system of land uses (abbasi et al., 2007; tessema, 2008). in berchernamocheya kebele, soil textural class of cultivation land (cl), el, gl, and nf were loam, clay loam, sandy clay loam, and sandy loam, whereas in badnayegor kebele, textural class of cultivation land (cl), el, gl) and nf was sandy clay loam, clay loam, sandy loam and loam (table 1). changes in textural class among land uses resulted from amendment in management practices and pedogenic practices at the study area. 3.2.soil bulk density and total porosity the analysis of variance depicted that land uses significantly (p < 0.01) affected bulk density (bd) in both kebeles. numerically, the highest bd was found under the grazing lands (1.41 g/cm3 and 1.44 g/cm3) followed by cultivated lands (1.38 g/cm3 and 1.34 g/cm3). however, the lowest value of bd (1.21g/ cm3 and 1.17 g/cm3) was detected under nf followed by the soil under el (1.28 g/cm3 and 1.18g/cm3) for berchernamocheya and badnayegor kebeles, respectively. aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 53 table1. mean values of selected soil physical properties land uses berchernamocheya kebele badnayegor kebele percentage (%) percentage(%) sand clay silt tx. c sand clay silt tx. c cl 44.33a 21.0b 34.67ab l 46.33b 28.33a 25.33b sl el 32.33b 28.33a 39.33a cl 41.0c 30.0a 29.0ab cl gl 47.0a 28.33a 24.67c scl 55.67a 18.33b 26.0b sl nf 52.33a 16.67c 31.0cb sl 48.33b 15.33b 36.33a l lsd (0.05) 9.6 4.3 7.11 4.61 4.61 7.69 cv% 11.59 9.72 11.64 5.12 10.65 13.99 land uses bd/gcm3 tp (%) bd/gcm3 tp (%) cl 1.38a 48.05b 1.34a 49.56b el 1.28ab 51.69a 1.18b 55.59a gl 1.41a 46.78b 1.44a 45.53b nf 1.21b 54.47a 1.17b 55.97a lsd (0.05) 0.14 5.31 0.13 19.03 cv% 4.08 4.04 5.51 5.15 cmol(+) kg-1 cmol(+) kg-1 land uses ph (h2o) ea ex. al ex. h pas ph (h2o) ea ex. al ex. h pas cl 4.80b 3.80ab 2.82a 0.98b 45.96a 5.0b 3.4ab 2.54b 0.86a 26.53a el 4.87b 5.25a 3.29a 1.96a 34.19a 4.93b 4.91a 3.91a 0.99 a 37.45a gl 5.53a 2.04cb 1.06b 0.88b 9.69b 5.53a 2.27cb 1.29bc 0.97a 11.09b nf 5.67a 1.06c 0.30b 0.76b 5.18b 5.63a 1.29c 0.27c 1.03a 6.24b lsd (0.05) 0.27 1.96 1.58 0.73 12.73 0.27 1.52 1.35 0.77ns 12.41 cv% 2.71 24.2 24.78 26.0 18.46 2.68 27.23 25.79 22.51 13.79 meq/100g soil meq/100g soil ca mg na k ca mg na k cl 3.33b 0.69b 0.25b 0.23b 7.67cb 2.09b 0.09b 0.26c el 6.0b 3.33b 0.19b 0.44b 4.33c 3.0b 0.10b 0.73b gl 10.0a 7.33a 0.63a 1.07a 9.0ab 7.67a 0.43a 1.29a nf 11.0 a 7.33a 0.36b 0.99a 12.33a 6.0a 0.32a 0.74a lsd (0.05) 3.92 3.01 0.26 0.52 3.77 2.54 0.17 0.32 cv% 27.45 14.27 19.45 20.71 24.00 17.75 18.29 17.71 n.b. the mean values in the table that are followed by the same letter are not significantly different from each other at p < 0.05, gl= grazing land, cl= cultivation land, el= eucalyptus land, nf= natural forest, cv= coefficient of variation, lsd= least significant difference, ea= exchangeable acidity, ex. al= exchangeable al, ex. h= exchangeable h, pas=percentage acid saturation. the possible reason why the bd was higher in gl and cl as compared to nf and el could be attributed to the compaction effect of livestock during free grazing, deforestation, and consequent tillage practices that might have resulted in worsening soil structure, which in turn leads to soil compaction (muche et al., 2015). the lowest soil om available in the cultivation land can also subsidize the highest bd. in addition to this, the current finding is in line with wakene and heluf (2003), who stated that the highest bd detected in unrestricted land was caused by soil compaction and deprivation of om. according to ratings by hazelton and murphy (2007), soil bd is rated as very low (<1 g/cm3), low (1-1.3 g/cm3), medium (1.3-1.6 g/cm3), high (1.6 -1.9 g/cm3) and very high (>1.9 g/cm3). aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 54 table 2. mean values of selected soil chemical properties. land uses berchernamocheya kebele badnayegor kebele meq/100g soil meq/100g soil teb ecec cec pbs teb ecec cec pbs cl 4.51c 8.31c 24.28c 18.57c 10.12b 13.52b 28.07b 36.22a el 9.96b 15.22b 30.03b 33.17b 8.17b 13.08b 32.67b 26.33a gl 19.03a 21.08a 30.13b 63.16a 18.39a 20.66a 42.07a 43.71a nf 19.65a 20.71a 35.0a 56.49a 19.39a 20.68a 43.27a 44.81a lsd (0.05) 2.87 2.67 3.67 10.39 4.09 4.17 7.90 23.08ns cv% 11.48 8.69 6.49 12.94 15.51 13.03 11.49 23.33 (mg kg-1) cmol(+) kg-1 (mgkg-1) cmol(+) kg-1 land uses av.p oc om tn c: n av. p oc om tn c: n cl 1.09c 1.35c 2.33c 0.14b 9.59ab 1.36b 1.40d 2.42d 0.20b 7.19b el 0.32d 2.17b 3.77b 0.24b 9.02ab 0.63b 2.47c 4.27c 0.21b 11.56a gl 2.54a 1.55c 2.69c 0.21b 6.29b 2.37a 3.37b 5.78b 0.46a 7.37b nf 1.77b 5.93a 10.2a 0.51a 11.71a 2.50a 5.47a 9.40 a 0.50a 10.9a lsd (0.05) 0.59 0.57 0.99 0.11 4.07 0.80 0.45 0.78 0.05 1.93 cv% 18.05 10.94 11.12 20.79 17.02 17.81 7.55 7.59 8.24 11.08 land uses bph lrsmp t/ha lrea t/ha bph lrsmp t/ha lrea t/ha cl 5.63a 11.3a 5.1ab 5.73c 10.2a 4.55ab el 5.80a 9.7a 6.7a 5.80cb 9.5ab 5.72a gl 6.17a 6.0a 2.8cb 6.10ab 6.6cb 3.29cb nf 6.33a 4.7a 1.3c 6.40a 4.1c 1.5c lsd (0.05) 0.74 7.1 2.58 0.33 3.02 1.9 cv% 4.73 24.15 17.41 2.92 21.1 n.b. means within a column followed by the same letter are not significantly different from each other at p < 0.05, bph = buffer ph, lrsmp= lime requirement determination method as shoemaker, mclean, and pratt, lrea= lime requirement determination method by extraction of exchange acidity, av. p= available p, oc= organic carbon, om= organic matter, tn= total n, pbs= percentage base saturation, cec= cation exchange capacity, teb= total exchangeable bases, ecec= effective cation exchange capacity, ns = non-significant. soil total porosity (tp) is a signal of the degree of compaction in the soil. analysis of variance reveals significant (p < 0.01) differences in tp among land uses for badnayegor and berchernamocheya kebeles. the highest tp (54.47% and 55.97%) was detected in natural forest land followed by el (51.69 and 55.59 %). in contrast, the lowest mean values (46.78% and 45.53%) of tp were registered under grazing lands followed by cl (48.05% and 49.56%) for berchernamocheya and badnayegor kebeles, respectively (table 1). alterations in tp among land uses might be due to high soil om and lowest bd of natural forest lands and low om content and high compaction due to the flattening effect of livestock during unrestricted foraging in grazing land. factors that affect bd have also a direct effect on tp. the results of the current study are in agreement with gebrelibanos and mohammed (2013), who asserted that the high tp in the soil of natural forests is accredited to higher om, as tp is affected by the level of soil om and bd (habtamu et al. 2014). according to the ranking of fao (2006), soil tp (< 2%) was classified as very low,(5-10%) low, (10-15%) medium, (15-40%) high, and ( > 40%) very high. based on this rating, the tp of aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 55 all land uses was found to be very high (> 40%). higher tp implies better aggregation and provides good aeration for microorganisms and an opportunity for crop production. 3.3.soil chemical parameters soil ph was highly significantly (p < 0.01) affected by land uses. comparison of the mean ph value of cultivation and eucalyptus lands with grazing and natural forest lands indicates statistically significant differences in berchernamocheya and badnayegor kebeles. however, there were no significant differences between el and cl as well as between gl and nf lands of the two kebeles (table 1). relatively the highest (5.67) and the lowest (4.8) ph were documented in the natural forest and cl of berchernamocheya kebele respectively. on the other hand, relatively the highest (5.63) and the lowest (4.93) ph were verified under the natural forest and el of badnayegor kebele respectively (table 1). low ph in cl and el could be due to high tillage frequency and high rates of annual rainfall that resulted in different forms of soil erosion, removal of plant residues after harvesting of plants, and leaching of basic cations. the current findings are consistent with previous findings that indicate soil ph was significantly lower in the soil of cl when compared to uncultivated soils (malo et al., 2005). consistent with the current study, gebeyaw (2015) also observed a significant alteration in ph value among land uses and showed lower ph in the soil of cultivation land. according to jones (2003), soil ph rated for berchernamocheya kebele, mean ph for cl, el, gl, and nf were respectively, 4.80, 4.87, 5.53, and 5.67 and the rating ranged from very strong acid for cl to moderate acid for nf. similarly, for soil ph rating for badnayegor kebele, the mean ph value for cl, el, gl, and nf was respectively 5.0, 4.93, 5.53, and 5.63, and rating ranges from very strongly acidic for cl to moderate acidic soil for nf (table 1). 3.4.exchangeable acidity (ea) and percent acid saturation (pas) the analysis of variance revealed ea and pas varied highly significantly (p < 0.01) through land uses in both kebeles. the mean ea values for cl, el gl, and nf lands were (3.8, 5.25, 2.04, and 1.06 cmol(+) kg1), and (3.4, 4.91, 2.27, and 1.29 cmol (+) kg-1) for berchernamocheya and badnayegor kebeles, respectively (table 1). the highest ea value was attained from el (5.25 cmol (+) kg-1) and (4.91 cmol (+) kg-1) and the lowest ea value was acquired from nf lands (1.06 cmol (+) kg-1) and (1.29 cmol (+) kg-1) for berchernamocheya & badnayegor kebeles, respectively (table 1). the mean pas values for cultivated land, el, gl, and nf land were (45.96, 34.19, 9.69, and 5.18 cmol (+) kg-1) and (26.53, 37.45, 11.09, and 6.24 cmol (+) kg-1) for berchernamocheya and badnayegor kebeles respectively (table 1). the highest pas value was achieved from cultivation land the pas (45.96 cmol (+) kg-1) and the lowest (5.18 cmol (+) kg-1) value was achieved from nf land of berchernamocheya kebele. likewise, the highest pas attained from el (37.45 cmol (+) kg-1) and the lowest (6.24 cmol (+) kg-1) pas value was achieved from nf land of badnayegor kebele. 3.5.exchangeable bases the analysis of variance depicted that mean values of exchangeable cations (ca2+, mg2+, na+, and k+) were highly significantly (p < 0.01) different across land uses for badnayegor kebele while ca2+ and mg2+ and na+ and k+ were highly significantly (p < 0.01 and p < 0.05 respectively) diverse for berchernamocheya kebele. the highest mean values of exchangeable bases ca2+ and mg2+ (11.0 and 7.33) were recorded in the soil of nf land and na+ and k+ (0.63 and 1.07) were recorded in the soil of gl. the lowest mean values of exchangeable bases ca2+, mg2+, and k+ (3.33, 0.69, and 0.23) were recorded in the soil of cl, and na+ (0.19) was recorded under eucalyptus land for berchernamocheya kebele, respectively. similarly, the highest mean values of exchangeable cations ca2+ (12.33) in nf land and mg2+, na+, and k+ (7.67, 0.43, and 1.29) were registered under gl, whereas the lowest mean values of exchangeable cation ca2+ (4.33) were registered under eucalyptus land, and mg2+, na, and k+ (2.09, 0.09 and 0.26) were recorded under cl for badnayegor kebele respectively (table 1). the relatively high exchangeable (ca2+ and mg2+) observed in soils of nf land might be due to the presence of relatively higher soil om and low exposure to soil erosion under nf lands. however, lower exchangeable ca2+ and mg2+ were observed in soils of cl and el soils, which resulted from lower ph and soil om as well as due to continuous removal of ca2+ and mg2+ with crop harvest from topsoil. the present aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 56 finding was in covenant with aboytu (2019) who showed that soil acidification limits the availability of essential nutrients from the top soils. the impact of high soil acidification results in a deficiency of available ca, p, and mo and domination of soluble al, mn, and other acid-forming metallic ions (getachew & sommer, 2000). 3.6.cation exchange capacity and percent base saturation the analysis of variance revealed that soil cec was highly significantly (p < 0.01) affected by land uses at the two kebeles. accordingly, the highest (35.0 cmol (+) kg-1) cec value was observed in nf soil, followed by gl (30.13), while the lowest (24.28) in cl soil, followed by el (30.03) for berchernamocheya kebele. the highest (43.27) cec value was observed in nf land soil, followed by gl (42.07), whereas the lowest (28.07) was recorded in cl, followed by el (32.67) for badnayegor kebele (table 2). a possible reason for the highest and lowest cec in nf land and cl respectively might be due to high soil om in fl land but low level of om and high leaching of basic cations from cultivation land. this finding was in agreement with the findings of bore & bedadi (2015), who stated that the decline in soil properties is mainly due to the transformation of native forest and range land into cultivated land. according to hazelton and murphy (2007), the cec of soils in cl was medium (24.28) & high (28.07) for berchernamocheya and badnayegor kebeles respectively; cec in el soil was high for both kebeles. high cec was revealed in grazing land (30.03) and nf land (35.0) for berchernamocheya, and very high cec was confirmed in grazing land (42.07) & nf land (43.27) for badnayegor kebeles (table 2). the value of pbs showed a highly significant (p<0.01) difference amongst land uses in berchernamocheya kebele. however, it showed an insignificant (p > 0.05) difference among land uses in badnayegor kebele. likewise, numerical variations were observed among the four land uses. relatively, the highest pbs (63.24%) was observed in grazing land, followed by nf land (56.49%), while the lowest pbs (18.57%) was recorded in cl, followed by el (33.17%) in berchernamocheya kebele. the reason for the high pbs content in grazing land in this kebele is probably due to the high total exchangeable bases (teb) content noted in gl, while the low pbs documented in cl is probably due to the presence of a lower level of total exchangeable bases (teb) observed in cl, low ph values and soil om and removal of basic nutrients from topsoil by erosion and crop harvest for the berchernamocheya kebele (table 2). the findings of the current study agree with the findings of jobira (2018) and kedir (2015), who reported that the highest pbs (57.87%) was measured in gl soil, whereas the lowest (31.23%) was recorded in cl soil. 3.7.soil organic matter, total n, c: n ratio and available p the analysis of variance showed that soil om was very highly significantly (p < 0.001) affected by land uses in both kebeles. the highest (10.2 %) and (9.40%) som were documented in the soil of nf land, while relatively lowest (2.33 %) and (2.42%) som were recorded in the soil of cl for berchernamocheya and badnayegor kebeles, respectively. the mean value of som increased from cl to gl, el, and nf lands and from cl to el, gl, and nf land at berchernamocheya and badnayegor kebeles, respectively (table 2). the highest soil om recorded in the nf land is due to the fall of plant biomass like leaves, barks, limbs, and other remaining plants and low exposure to soil. conversely, the lower som of cl is probably due to the removal of som through oxidation, which is resulted from the mismanagement of cultivated land triggered by intensive cultivation and soil erosion, which then leads to the washout of soil om. according to tekalign et al., (1991), (< 0.86) om is rated as very low, (0.86-2.59 %) low, (2.59-5.17%) medium/moderate, and > (5.17%) high. based on this rating, the om for cl, gl eucalyptus plantation land, and nf land in berchernamocheya kebele were 2.33%, 2.69%, 3.77%, and 10.2% respectively. the mean values of som for badnayegor kebele were 2.42%, 4.27%, 5.78%, and 9.40% in cl, ep, gl, and nf land respectively. the result indicated that som was low under cl of both kebeles, medium under eucalyptus and gl, and high under nf lands of both kebeles (table 2). the total n was very highly significantly (p < 0.001) affected by different land uses in both kebeles. the highest mean values (0.51% and 0.50%) of the tn were aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 57 documented in nf lands, while the lowest (0.14% and 0.20%) were noted in cl of berchernamocheya and badnayegor kebeles respectively (table 2). this might be due to comparatively high som content noted in natural fl and low som content in cl as well as due to land use change from natural fl to cl, which may trigger the decline of tn content. this result is congruent with the findings of (dawit et al., 2002). based on the rating suggested by barber (1984), the tn content recorded in cl was low for both kebeles, medium in grazing and el lands in berchernamocheya kebele and eucalyptus land in badnayegor kebele, and very high in nf lands at both kebeles (table 2). the result of the c: n ratio showed significant (p<0.05) and highly significant (p<0.01) variations amongst land uses in berchernamocheya and badnayegor kebeles, respectively (table 2). the highest (11.71) c: n was noted in nf land, followed by cl (9.59), while the relatively lowest (6.29) c: n was documented in gl, followed by el (9.02) in berchernamochya kebele. similarly, the highest (11.56) c: n was documented in el, followed by nf land (10.9), while the lowest (7.19) c: n was observed in cl, followed by gl (7.37) in badnayegor kebele (table 2). low input of soc, removal of crop residues from cl, and overgrazing are probably the reasons for a low level of c: n in cl and gl, whereas higher c: n is probably due to higher contents of soil oc and high plant biomass in natural fl. similarly, previous findings also stated that narrow c: n at the surface soils of cl is probably due to higher microbial activity in the surface 0-20 cm soil layer (chimdi, 2014). based on the ratings by hazelton and murphy (2007), we have found out that except for natural fl, which was low c: n, for all the remaining land, uses, the c: n was rated as very low at grazing and cl in berchernamocheya kebele, low at the ep land and natural fl in badnayegor kebele (table 2). available p was highly significantly (p<0.01) affected by land uses in both kebeles. relatively, the soil under grazing land was documented with the highest available p (2.54 mg/kg), followed by nf land and cl (1.77 and 1.09mg/kg) respectively; the lowest (0.32mg/kg) was noted in el in berchernamocheya kebele. on the other hand, the highest available p was noted (2.50 mg/ kg) in nf land, followed by grazing and cl (2.37 and 1.36 mg/kg) respectively, and the lowest (0.63 mg/kg) was registered in el in badnayegor kebele. this result agrees with the finding of tessema (2008), who reported that low available p in acid soils is due to the inherently high p fixing capacity of the soil. as rated by barber (1984), the available p was qualifying very low in all land uses in both kebeles; however, it is numerically better in soils of nf land and gl of both kebeles (table 2). 3.8.lime requirement(lr) determination with the smp buffer solution method the amount of lime required by using the buffer solution method of lime requirement determination (lr_smp) of the experimental soil was highly significantly (p < 0.01) affected by land uses at badnayegor kebele; however, it is insignificantly affected by land uses at berchernamocheya kebele (table 2). accordingly, the highest (10.2 t/ha) value of lr was noted in cl soil, followed by ep land (9.5 t/ha), while the lowest (4.1 t/ha) was documented in nf land soil, followed by gl (6.6 t/ha) at badnayegor kebele. a possible reason for the highest quantity of lr verified in cl and el is probably due to lower om content, low ph values, relative existence of substantial quantity of al and h ions, and low level of basic nutrients. however, a lower quantity of lr was documented in nf and gl soil is probably due to relatively higher om content, high ph (above 5.5), and high quantity of basic nutrients. the quantity of lime requirement determined by using buffer solution method of lime requirement determination smp methods to change the current ph value of soils to targeted ph 6.5 was in line with the finding, cl and gl required 14.0 15.90 ton/ha of lime to change the soil from 5.13-6.5 by smp buffer solution method (birhanu, 2008). 3.9.lime requirement determination with exchangeable acidity method the mean values of lr evaluated using the extraction of exchange acidity method were highly significantly (p < 0.01) affected by different land uses in both kebeles. the study revealed the highest (6.7 and 5.72) t/ha mean value of lr in el soil, followed by cl (5.1 and 4.55) t/ha, and the lowest (1.3 and 1.5) t/ha in nf land, followed by gl (2.8 and 3.29) t/ha in berchernamocheya and badnayegor kebeles, respectively (table 2). a possible reason for the difference in lr among land uses is probably due to high aliyu nesru et al ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 58 om, high ph values, and lower amount of exchangeable acidic cation (al+ and h+). low acid saturation was recorded in nf land and gl in the study area requires a relatively low quantity of lime. however, soils under cl and el require a high quantity of lime probably due to low om content, lower ph values, a relatively higher quantity of acidic cation (al+ and h+), and high acid saturation. this means that when the soils contain a substantial value of acidic cations, a higher quantity of lime is required to reclaim soil acidity (desalegn et al., 2017). 3.10. comparison of lime requirement determination methods of the two lime requirement determination methods stated above, lime requirement determination by using the buffer solution method (lr_smp) was exaggerated (4.1 t/ha to 11.3 t/ha) across the land uses. however, in lime requirement by using the extraction of exchangeable acidity method, the quantity of lime required ranged from 1.3 t/ha to 6.7 t/ha across land uses for the study area. the quantity of lime required by using the extraction of exchangeable acidity method was very low for nf lands (1.3 t, 1.5 t) and gl (2.8 t, 3.29 t) as compared to the amount of lime required by using the buffer solution method, where the quantity of lime required for nf lands (4.7 t, 4.1 t) and grazing lands (6.0 t, 6.6 t) was very high for berchernamocheya and badnayegor kebeles respectively. similarly, the quantity of lime required by using the extraction of exchangeable acidity method was very low for cl (5.1 t, 4.55 t) and el (6.7 t, 5.72 t) as compared to the quantity of lime required by using the buffer solution method for cl (11.3 t, 10.2 t) and el (9.7 t, 9.5 t), which was very high for berchernamocheya and badnayegor kebeles respectively (table 2). although lime requirement can be determined both through smp buffer and exchangeable acidity methods, a more suitable method should be identified by validating it under field conditions. 4. conclusion the assessment of soil acidity in four land uses showed that very low soil ph (4.8 and 4.87), (5.0 and 4.93); and higher acid saturation (45.96% and 34.2%), (26.53 and 37.45) were recorded in cl and el for berchernamocheya and badnayegor kebeles, respectively. the findings of the study also indicated overall variation and loss of soil fertility in cl and el as compared to nf land and gl. accordingly, cl and el soils were also poor in macronutrient contents and fell below teb (from 4.51 to 13.52), cec (from 24.28 to 32.67), and pbs (from18.57% to 33.17%). however, relatively higher soil ph (>5.5) and lower acid saturation (from 5.1% to 11.09%) in nf land and gl soils indicated its suitability for better available nutrients. the teb ranged from (19.03 to 19.65); cec from (30.13 to 43.27) and pbs from (43.71% to 63.16%) were recorded in the soil of nf land and gl. based on the evaluation of lime requirement under the four land uses, we have observed that the quantity of lime required varies greatly among land uses. this variation is probably due to low ph values in cl and el soils, which require a higher quantity of lime than adjacent nf land and gl. finally, this soil acidity and reduction of basic cations lead to the intensification of risks to agricultural productivity. immediate and integrated land management interventions are required to overcome soil acidity, improve soil productivity, and achieve viable agricultural crop production. . application of agricultural lime and organic fertilizers is considered a dominant measure for such acidified cultivated land. finally, we recommended that further studies are needed on lime recommendation rates in the study area based on locational field 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(in sustainable land management and poverty alleviation, issue. https://doi.org/doi https://doi.org/10.1155/2020/3713967 72 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper practices and challenges of corporate social responsibility in ethiopia: the case of dangote cement factory, ada’a berga district, west shoa zone, oromia regional state degaga tesfaye asnake1,*, dereje dugassa hirpha2, gemechu shale ogato3 1department of sociology, college of social sciences and humanities, ambo university p.o.box19, ambo, ethiopia 2department of social work, college of social sciences and humanities, ambo university p.o.box19, ambo, ethiopia 3department of rural development and agricultural extension, icds, ambo university p.o.box19, ambo, ethiopia *corresponding author, e-mail: shibetas@gmail.com abstract corporate social responsibility (csr) is the way organizations integrate social, environmental and economic concerns in a transparent and accountable manner. studies done in the past overstressed the financial aspect of csr and provided less attention to the environmental and social perspectives. the study was aimed at assessing practices and challenges of csr in dangote cement factory of ethiopia. specifically, the study addressed issues pertaining to environmental protection, employment creation and challenges of its implementation. survey respondents, fgd discussants and key informants were selected using simple random, convenience and purposive sampling techniques respectively. questionnaires, key informant interviews and focus group discussion checklists were used to collect primary data. while the quantitative data were analyzed using descriptive statistics (frequency and percentage) and presented using tables, qualitative data were analyzed through narrative and thematic analysis. with regard to environmental protection, the findings of the study revealed that ‘fog of dust which emitted during transportation covered all over the area. large number of vehicles and workers continuously flocking in the vicinity of the cement factory also overcrowded the local environment and this in turn increased t he volume of wastes. though the company created employment opportunities for the local communities, most of the employment opportunities were found to be below-profile and less attractive. furthermore, the findings indicated that lack of commitment on the part of the factory’s top management and over-ambitious expectations on the side of the local community were the major challenges to implement corporate social responsibility. these challenges call for collaboration of the company owners, management bodies, the government, and the local communities to properly implement corporate social responsibility. keywords: challenge, corporate social responsibility, dangote, local communities. 1. introduction corporate social responsibility (csr), a concept that has been around for over 50 years, has become prominent again recently. scholars of corporate social responsibility of business organizations assert that an increasing number of transnational corporations (tncs) and large domestic companies, supported by business and industry associations, are adopting a variety of socalled voluntary csr initiatives(baxi, 2005; utting, 2005). csr may refer to the responsibility of enterprises for their impacts on society and highlights the principles that encourages enterprises to have in place a process to integrate social, environmental, ethical human rights, and consumer concerns into their business operations and core strategy in close collaboration with their http://www.ejssd.astu.edu/ degaga tesfaye et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 73 stakeholders(berenbeim, 2006; christina, 2008; crane & matten, 2011; the european commission;2011). companies also create jobs and help finance the general welfare of the population as attested by burke (2005). this indicates that corporations around the world are struggling with a new role, which is to meet the needs of the present generation without compromising the ability of the next generations to meet their own needs (crowther & aras, 2008). business organizations are also being called to take responsibility for the ways in which their operations impact societies and the natural environment (marrewijk & werre, 2003; narwal & singh, 2013; undp, 2002). as a result, organizations have developed different strategies to deal with the intersection of societal needs, and the natural environment through csr (enquest et al., 2006). csr addresses complex and critical issue such as human rights, environmental protection, equal opportunities for all, fair competition, and the interdependencies that occur between organizations and society (quinn, 2008). despite the aforementioned initiative, in developing countries like ethiopia, practices of csr in fulfilling the multifaceted social needs are claimed to be challenging as it tends to put too much pressure on companies to satisfy such and other societal needs (baughn et al., 2007; jeremy, 2006). however, there are grave concerns about the need to mainstream csr into business operations of organizations to solve some imperative setbacks facing the poorest parts of the world considering the fact that majority of csr initiatives are driven by the western organizations (banerjee, 2008) different global level studies that were carried out in the past overstress the financial aspect of csr and provided less attention to the environmental and social issues (tsoutsoura, 2004). however, surveys of csr amongst businesses in african countries, mostly south africa, ghana, namibia and malawi have found that the most common approach to csr issues is through philanthropic support, focusing on education, health and environment (kusku & zarkada, 2004). visser et al. (2008) argued that in africa, csr is confined to certain activities, mainly charity, community development programs and philanthropy. in ethiopia, most of the previous studies (fentaye & mohan, 2016; mathias, 2015; mechale & shiibre, 2011) were conducted on alcoholic and horticultural industries. these studies attempted to investigate the practices of csr, focusing on limited stakeholders while disregarding others (fentaye & mohan, 2016; natta, 2012).therefore, cognizant of the inevitable effect of such misrepresentations on the outcomes of these studies’ to fill the gap, the researchers approached the problem under study by incorporating views of all the main stakeholders such as the company managers, employees, local community members and district administrators. although the company has been frequently facing allegations and challenges from local communities on different occasions, there was no much relevant study conducted in the company from corporate social responsibility perspective. hence, the study was underpinned by the aforementioned rationale and previous csr studies in ethiopia focused on serviceoriented economic sectors and studies on cement companies from csr perspective are scant (yeung, 2011).hence, this study was aimed at assessing the extent to which dangote cement factory is executing its corporate social responsibilities and the major challenges it is facing in this regard. 2. methods and materials the study was conducted on dangote cement factory, located in ada’a berga district, west shoa zone of oromia regional state. geographically, the district is located at 64 kms north west of addis ababa on the road of mugher cement enterprise at 9° 12’ to 9° 37’ n latitude and 38° 17’ to 38° 36’ e longitude. it has a climatic condition of 21% highland, 54% mid latitude and 75% lowland and three main agro-climatic regions; “daga” (28%), “winadega” (38%) and “kola” (34%). dangote cement is african leading cement producer in 16 african countries with revenue of usd 2billion and nearly 17,000 employees. dangote cement in ethiopia is the largest plant capable of producing high-quality cements to meet market needs since may 2015. the information obtained from dangote human resource officer showed that the company was established on 134 hectors of land. it also has 1243employees (permanent 1158 and 85 contractual workers). 2.1. research design and methods the study employed a mixed research design where a case study and descriptive survey research designs degaga tesfaye et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 74 were combined. while case study research design was employed to narrate some qualitative aspects of the study through focus group discussion and key informant interview, descriptive survey design was employed in conducting employees’ survey in october, 2017 to assess practices and challenges of corporate social responsibility in dangote cement factory from employees of the company. the company’s employees and local communities were the sources of data to undertake the study. the data were triangulated by employing qualitative and quantitative methods of data collection and analysis to enhance the reliability and validity of the generated information. the study employed both probability and nonprobability sampling techniques as sampling methods of the study. with regard to the former one, a simple random sampling technique was employed. accordingly, from the total population of 1243 company employees, 138 were selected using yemane’s (1967) formulas (equation 1) for the employees’ survey questionnaire. hence, the researchers adopted a confidence level of 92% and the margin of error of 8% which is acceptable in social science research. 𝑛 = n 1 + n(𝑒 2) (1) where, 𝑛 = sample, n = total population and e = margin of error at 8%. participants of the qualitative methods of data collection were selected using convenience and purposive sampling techniques. convenience sampling technique was employed for fgd considering accessibility of displaced communities. hence, four fgds were held with the local community members (two fgds with elders and two fgds with local youths) to explore their perceptions on the company’s csr in relation to environmental protection and provision of social services. key informant interviews were administered with two managers of the company, two agency workers and ada’a berga district administrator (a total of five key informants were interviewed). the interviewees were selected purposively because these individuals were supposed to provide detail information as they are experienced and knowledgeable about the issue under investigation. quantitative data collected through employees’ survey were analyzed using simple descriptive statistics (percentage and frequency) while qualitative data collected through focus group discussion and key informant interview were analyzed through thematic analysis and narrative analysis. the major criteria underpinning the combined application of the aforementioned two qualitative methods of data analysis were: transparency, maximizing validity, maximizing reliability, comparative analysis, and reflexive approach in the process of analysis. the major steps involved in the process include: 1. reading and annotating transcripts; 2. identify themes; 3. developing a coding scheme; and 4. coding the data. 3. results and discussion this section presents results and discussion. to this end, analysis of quantitative data was presented in tables while qualitative information was presented through narrations and qualitative arguments. finally, the results were compared with findings in existing literature in relation to the issues investigated with the aim of discussing the results. 3.1. socio-demographic characteristics of respondents with regard to gender, 81.9% (n=113) of the respondents were males while females account for 18.1 % (n=25). the highest and the lowest age of respondents were 20 and 48 respectively. more proportion of the respondents (37.7%; n=52) were in active age group (26-30) and have the potential to play role in the production of the organization if managed properly. the data show that 62.3.7% (n=86) of employees were single whereas 37.7 % (n=52) were married at the time of the interview. as far as their educational status is concerned, (39.9 %; n=55) of the respondents were firstdegree holders; 25.4 % (n=35) were diploma holders; 20.3 % (n=28) were masters and above; 10.1 % (n=14) were with certificate; and 4.3 % (n=6) were high school graduates. 3.2. practice of the factory in environmental protection companies acquire raw material from rural areas for their industries. pollution on air, water and land is inevitable during the process of production and processing of their products. with increasing significance of environmental friendly products, processes, and services, firms are recognizing the value degaga tesfaye et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 75 of adopting environmental standards for their sustainability in the long run. in this study, respondents were asked about the corporate social responsibility of their organization towards environmental protection or organizational practice of protecting the environment from pollutions. as can be seen from table 1, 61.7% (n=87) of the survey respondents reported that no dust has been released to the local environment; 31.7% (n=44) reported that no air pollutants such as co2 released to the external environment during production and 7.1%(n=7) of them opined that the factory has been playing its role in planting trees around. table 1: areas of environmental protection the results of the key informant interviews (kiis) made with company managers indicate that dangote cement factory has environmental impact assessment policy. in relation to this, one of the key informant states, ‘‘…our company has environmental impact assessment policy and in the normal cement production, no dust is emitted to the local environment even though dust emission occurs during transportation of cement...” (key informant one). recent trends also show that similar business firms are spending more resources on environmental protection practices and are seeking proactive actions to reduce the environmental impacts of their actions (banjere, 2001; king, 2009; marrewijk & werre, 2003). however, the result of focus group discussions (fgds) held with locally displaced communities (elders and youths) indicate that there is exacerbated environmental pollutions in the local environment due to large number of workers coming to the area and related increase in volume of waste released to the environment. this indicates that the company did not implement its environmental impact assessment policy as the local communities claimed that the local environment is polluted due to improper management of wastes relating to the operation of the company in the local environment. 3.3. practice of the factory in creating employment opportunities the social responsibility of a firm is also measured in terms of employment opportunities it created for local communities. respondents were asked to express their feeling on whether dangote cement factory of ethiopia has created employment opportunity for the local communities or not. as can be seen from table 2, (68.6%; n=95) of the respondents responded that the establishment of the factory in the area has created more employment opportunities for the local communities. on the other hand, 31.2 % (n=43) of the respondents contended that no significant employment opportunities are created by the company for the local communities. table 2: did the plant create employment to local communities? response frequency percentage yes 95 68.8 no 43 31.2 total 138 100.00 respondents were further asked to tell about the type of employment created for local communities after the establishment of the company in the area. table 3 reveals that the majority of the respondents (73.9 %; n=102) reported that the created employment opportunities for the local communities are permanent employment while 26.1 % (n=36) of them indicated that the created employment opportunities are contractual. this indicates most of the created employment opportunities are permanent. table 3: type of the created employment opportunities created employment frequency percentage contract employees 36 26.1 permanent 102 73.9 total 138 100.0 respondents were also further asked to explain about the way of employees’ recruitment by the company. as indicated in table 4, 67.4% (n=93) reported that workers’ recruitment in the company was made through vacancy announcement while 31.6% (n=45) of them areas of environmental protection frequency percentage no air pollution 44 31.2 no dust released to outside 87 61.7 conservation of natural resources/planting trees 7 7.1 total 138 100 degaga tesfaye et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 76 responded that workers’ recruitment was made without official announcement. table 4: mechanism of recruiting workers the kii made with factory workers also confirmed that individuals having close relatives/ network with some organizational figures such as top managers and agency owners were getting access to better employment opportunities. the responses of the following kii illustrate this:‘‘…most of the people working in the mineral site of the company came from shekiso while very few of them were from the local communities because agency owners responsible for hiring workers were also not from locals’’ (key informant two). the quantitative data revealed that most of the employees were recruited based on announcement though the results of kii indicate recruitment is done based on favoritism. according to the result from kii, agency workers have been giving little attention to the local communities. the data from ada’a berga district administrator also reveals that attention was not given to the local communities. with regards to this, one of the key informants stated, ‘‘…previously, one top manager passed a decision of firing 16 local people from their work when they requested him to renew their contract. he ordered his guards to shoot. he then replied for his coercive deed saying ‘in our country by firing nine, we can hire nine’...’’ (key informant three). this led local communities to feel pessimistic about the company and they lost any hope of benefiting from the employment opportunities. the finding of the study comply with the assertion of johnson (1971) who asserts that instead of striving for bigger profits, a responsible enterprise should also takes into account employees, local communities, and the nation at large. 3.4. perception of the local community towards the company’s csr practice it was emphatically stated that the main focal point of corporate social responsibility is the normative correctness of the products of corporate action (epstein, 2007). regarding perception of local communities, the fgd discussants acknowledged that local people have negative perception towards the company as the amount of money paid to those displaced from their land was insufficient for their livelihood. hence, majority of these people became daily laborers as a result of lack of education and mismanagement of the money they received as compensation. even questions related to ownership of their resources were diverted and given political connotation. to this end, one of the participants has claimed about this problem when he said “...most local residents are not appropriately receiving what they should have received as a means to reimburse for their assets (land). as a result, they wish the organization were not established in their area” (fgd participant two). according to banerjee (2008), corporations should be responsible to those who openly affect or are affected by their activities. however, the result of this study indicates that, in relation discharging its csr, the company did not comply with the assertion of the aforementioned scholar. as a result, local communities perceived the company negatively. 3.5. challenges to implement corporate social responsibility respondents were asked to tell the challenges of implementing corporate social responsibility in their organization. as indicated in table 5, 52.8% (n=73) of the respondents reported that lack of management support is the challenge while 15.9 % (n=22) stated that the implementation of csr drains financial resources of their company. this shows that more than half of the respondents perceived lack of management support as a challenge for implementing csr in dangote cement factory. one of the key informants also expressed his view in relation to lack of top management support for implementing csr when he said “…there is no strong commitment on the part of the company’s top management as they are outsiders and not much response frequency percent through announcement 93 67.4 without announcement 45 31.6 total 138 100.00 degaga tesfaye et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 77 concerned to address the local communities’ pressing issues like socio-economic and environmental issues other than maximizing company’s profits. sadly, top managers of the company strive to meet the interest of the company owners.”(key informant three). however, faulkner (1995) attests that the designing and implementation of corporate social responsibility requires long-term commitment and vision from managers. table 5: challenges in implementing csr moreover, the result obtained during kii demonstrated over-ambitious expectations of the local communities as another implementation challenges the company is facing in implementing csr. the scenario of this expectation was stated as follows: while displacing local communities to commence the plant, we convinced them that the coming of the factory would create employment opportunities. even graduates of un-related disciplines/ professions like animal sciences asked the mangers of the organization for employment due to this promise. furthermore, local people found in different strata (educated, uneducated, young, aged, students) etc. are wasting much of their time in requesting the company for employment (key informant four). this finding reveals similar implication with the study conducted by baughn et al. (2007); hatcher (2002); and stralecka (2006) who affirm that the implementation of csr is very much challenging as a result of the numerous needs of societies. 4. conclusion and recommendation 4.1. conclusion the current study was aimed at assessing practices and challenges of corporate social responsibility in dangote cement factory of ethiopia from social and environmental perspectives. in conclusion, the promises of the factory to provide social services led the local communities develop higher expectation; the local communities are much concerned about the environmental pollution in their area underpinned by the transportation of cement by heavy vehicles and poor disposal mechanisms of wastes. the company did not realize many of the promises it had given the local community at the time of establishment in relation to corporate social responsibility practices such as environmental protection and provision of social services. favoritism was claimed to be demonstrated in the employment procedures having adverse effect on the local communities. lack of top management support for implementing corporate social responsibility and overambitious expectations of the local communities were the major challenges that the company is facing in implementing corporate social responsibility. this led the local communities to lose their hope and trust on the organization. 4.2. recommendations based on the findings of the study the following recommendations were forwarded: recommendation for company management:  the management of the organization should adequately discharge the corporate social responsibility.  top management of the organization need to work closely with the local communities so that sense of ownership can be created among the locals communities; and  company management should abstain themselves from giving unattainable promises, which may lead to dispute and strike. recommendation for company owners:  owners of the factory are expected to reshuffle their management structure in order to create smooth relationship with local communities;  the owners should consider local people who have strong say in the communities to properly manage communities over-ambitious expectations;  owners of the factory should implement corporate social responsibility practices like protection of the local environment and provision challenges in implementing csr frequency percentage lack of management support 73 52.8 failure to engage key stakeholders 22 15.9 inadequate skills needed to csr 18 13.2 drains company’s resources 25 18.1 total 138 100 degaga tesfaye et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 78 of social services as stated in their project document in order to get acceptance among the locals. recommendation for the government and local communities:  the local government and local communities should not be over-ambitious in expecting the organization to address the entire development problems of the local communities;  there should be a continuous follow up on the part of the government specially the investment bureau (federal/regional) to check whether the organization is on the right track in implementing the promised csr practices as stated in its project proposal;  government should encourage the establishment of strong labor union so that major problems of the employee can be solved. acknowledgements the authors would like to thank the office of research and community service vice president of ambo university for its financial support. besides, we would like to thank all study participants. furthermore, our gratitude goes to peer reviewers and editors of this article. reference banerjee, s.b. 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(2011).the role of banks in corporate social responsibility. hang seng school of management, china. journal of applied economics and business research, 1(2): 103-115. 1 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper compressive strength characteristics of ara and apado nigerian timber species jimoh a. a., rahmon r. o.* department of civil engineering, faculty of engineering and technology, university of ilorin, nigeria * corresponding author, e-mail: rorahmon2222@gmail.com abstract the paper examined the reliability of the nigerian grown ara and apado timber species as column materials. the work focuses on the compressive strength characteristics of nigerian ara (pterocarpus erinaceus) and apado (berlinia spp) timber column of nominal lengths 200, 400, 600 and 800 mm and cross section of 50 by 50 mm. t he steps involved include collection and conditioning of apa and apado timber species, preparation of test specimens, determination of physical and compressive strength properties and derivation of continuous column design equations. twenty (20) test samples were used for all the tests carried out. apa and apado have an average density of 652.83 and 732.56 kg/m3, respectively. moisture content of both species is less than the maximum recommended value of 20 % and the average strength at yield of apa and apado were 38.81 and 29.61 n/mm2. the derived continuous equations for design of apa and apado column are σ = 47.882−0.009λ and σ = 17.211−0.007λ respectively. ara and apado have the reliability index of 0.63 and 0.65 respectively for a service life of 50 years, assuming other serviceability conditions are met. the paper therefore recommends the adoption of these equations for the design of compression members from these timber species, in nigeria. keywords: apado, ara, compressive strength, reliability, slenderness ratio. 1. introduction timber is a complex building material owning to its heterogeneity and species diversity. nigeria is one of the countries that have timber in surplus quantity. if this natural resource is properly utilized, it will be of immense benefit to the country in terms of reduction in the cost of construction (aguwa et al., 2015). timber does not have consistent, predictable, reproducible and uniform properties as the properties vary with species, age, site and environmental conditions (kliger, 2006). the strength of a timber depends on its species and the effects of certain growth characteristics (porteous and kermani, 2007). different wood species have different strength characteristics, and also within a species these characteristics may vary. therefore, in practice, a classification system of strength classes is used (jamala, et al., 2013). the need for local content in construction of engineering infrastructure is now a serious engineering challenge in nigeria (rahmon et al., 2017). this is because vast quantities of local raw materials, which must be processed and used for cost effective abound (aguwa, 2011). construction activities based on these locally available raw materials are major steps towards industrialization and economic independence for developing countries. this explains huge interest and considerable intellectual resources being invested in understanding the mechanical or structural properties of the nigerian timber (aguwa and sadiku, 2011). structural timber is the timber used in framing and load-bearing structures, where strength is the major factor in its selection and use. most woods used in the building construction are softwoods but in structures like bridges and railway sleepers, hardwoods are specially http://www.ejssd.astu.edu/ mailto:rorahmon2222@gmail.com jimoh a. a. and rahmon r. o. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 2 used (karlsen and slitskouhov, 1989). the raw materials research and development council of nigeria, rmrdc (1998) opined that the roof structure and ceiling noggins of most buildings are constructed with timber because of its workability and durability. timber is natural and renewable. it has a high strength to weight ratio and is easy to work with, making it especially useful even where only basic technology and procedures are available (apu, 2003). most of the timber strength properties recorded in british and european codes were based on timber obtained from trees on those areas and the laboratory tests were conducted there. since all nigerian timber structures are constructed of timber from nigeria, there is the great need to determine their strength properties and subject them to structural reliability analysis in order to prove their degree of structural performances. (aguwa, 2010). the reliability, r(t) of an item is defined as the ability of an item to perform a required function under stated conditions without failure for a stated period of time (adedeji, 2008; ajamu, 2014). reliability coefficients range from 0.00 to 1.00, with higher coefficients indicating higher levels of reliability. however, reliability specifically measures the consistency of an item. according to leitch (1988), reliability index using constant failure rate (cfr) model is given in equation (1): r(t) = 𝑒 −λt (1) where: r(t) = reliability index; λ = constant rate of failure; t = variable time and the failure rate (λ) is express as in equation (2): λ = 1 − 𝑑 𝑇 (2) where: t is the time (years), expected life span of timber, and d: the average compressive strength rate. nowak (2004) defines structural reliability as the probability that a structural system will satisfy the purpose for which it was designed and efficiently serve the period for which it was designed to without attaining a given limit state. structural reliability and probabilistic methods have gradually grown to be important in modern structural engineering practice, especially when it involves naturally occurring materials like timber. structural reliability could currently be used in the formulation of new generation design codes, evaluation of existing structures and probability risk assessment. one of the objectives for structural design is to fulfill certain performance criteria related to safety and serviceability. one of such performance criteria is usually formulated as a limit state, that is, a mathematical description of the limit between performance and non-performance (thelandersson, 2003). parameters used to describe limit states are loads, strength and stiffness parameters, dimensions and geometrical imperfections; since the parameters are random variables, the outcome of a design in relation to limit state is associated with uncertainty (aguwa, 2012). a significant element of uncertainty is also introduces through lack of information about the actual physical variability. the objectives of this study is to conduct experiments on the nigerian ara and apado timber species with a view to establishing their physical and strength properties, to check the conformity of these properties with bs 5268 (2002) and ncp 2 (1973), to derive continuous column design equations for the nigerian ara and apado timber species as column structural material, to estimate the reliability of the nigerian ara and apado timber species. 2. material and methods 2.1. material procurement pterocarpus erinaceus (ara) and berlinia spp (apado) timber species were obtained from tanke, odookun and saboline sawmills in ilorin, nigeria. they were naturally seasoned for six months for the samples to attain moisture content equilibrium environmentally. the natural seasoning was chosen over artificial seasoning which is faster because the proposed timber structure is column which is always completely exposed to natural atmospheric weather conditions. the timber samples were prepared and tested in accordance with the british standard bs en 408 (2003) test for physical and mechanical properties of structural timbers at the wood section of the civil engineering department, faculty of engineering and technology, university of ilorin, nigeria. timber lengths of 50 x 50 mm section obtained from each sawmill was cut into lengths 200, 400, 600 and 800 mm. a maximum height of 800 mm was used due to the limited height of the testing machine. a typical nomenclature is given in figure 1. jimoh a. a. and rahmon r. o. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 3 figure 1: lengths of timber species the physical property tests of the timber species was carried out at the structural laboratory of civil engineering department, university of ilorin, while the mechanical strength test was carried out using a universal testing machine (utm) of capacity 300 kn at the agricultural and biosystems engineering laboratory, faculty of engineering and technology, university of ilorin, kwara state, nigeria. 2.2. physical property tests 2.2.1. moisture content in accordance with british standard bs 373 (1957) method of testing small clear specimen of timber, immediately after each mechanical test has been conducted, a small sample for determination of moisture content was cut from each test piece. the sample size was 50 x 50 x 50 mm and consists of a transverse section from near the point of fracture. the sample was weighed and then dried in an oven at a temperature of 103 ± 2 °c (217 ± 4 °f) until the weight is constant. the loss in weight expressed as a percentage of the final oven-dry weight is taken as the moisture content of the test piece. moisture content (m.c) in percentage is given as: 𝑚. 𝑐. % = 𝑊𝑎 − 𝑊0 𝑊0 𝑥 100% (3) where: wa = air-dried weight of sample at test in grams, w0 = oven-dried weight of sample in grams. 2.2.2. density density of a material is the ratio of the mass to the volume. in the 50 by 50 mm standard given by bs 373 (1957), all test pieces weight and dimensions were determined before test. the density is given as: 𝜌 = 𝑊𝑎 𝑉𝑎 = 𝑊𝑎 𝐵𝑥𝐷𝑥𝐻 (4) where: ρ = density in kg/m3, b = breadth in cm, d = depth in cm, h = height in cm, wa = air-dry weight of sample at test in grams (g), va = air-dry volume of sample at test in cubic centimeters (m3). 2.3. mechanical property tests 2.3.1. compressive strength compressive strength test was carried out using a testometric universal testing machine. the following procedures were carried out: i. the timber was cut into various sizes (200, 400, 600 and 800 mm); twenty samples for each of the sizes and then labeled. ii. the machine height was now adjusted to the sizes of the specimen. then the timber was fixed for loading. iii. the speed of the test was calculated according to bs 373 (1957) (table 1). table 1: test speed iv. the nominal length, the test speed, weight, breadth, width of the samples was inputted into the computer. v. the machine was started and load deflection curve can be seen on the computer, the machine was stopped when the sample fails or when the curve starts to deflect downward. vi. the buckling was measured, and the sample taken out of the machine. vii. the steps were repeated for the remaining samples. viii. from the load deflection curve obtained after the test, the stress (σ) and strain (ε) is calculated. σ (n/mm2) = 𝑃 𝐴 (5) ε (%) = δh 𝐻 (6) member slenderness was calculated as follows: slenderness ratio, = le r (7) , where le = 1.0l, radius of gyration, 𝑟 = √ 𝐼 𝐴 (8), where 𝐼 = 𝐵𝐷3 12 , a = b*d and λ = slenderness ratio, le = effective length, sample length (mm) test speed (mm/min) 200.00 13.020 400.00 26.040 600.00 39.060 800.00 52.075 jimoh a. a. and rahmon r. o. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 4 r = radius of gyration, i = moment of inertia, a = crosssectional area, l = length, b = breadth, d = depth. 3. results and discussion 3.1. density the results of density are shown in table 2. from the results, it was observed that the average density of pterocarpus erinaceus (ara) is 452.83 kg/m³ while that of berlinia spp (apado) is 732.56 kg/m³. this implies that apado has higher yield strength than ara. table 2: average density of ara and apado specie average density (kg/m3) ara apado minimum 324.53 548.27 maximum 587.23 742.67 mean 452.83 732.56 standard deviation 45.44 54.33 cov (%) 24.57 19.43 95% confidence limit 424.67≤x≤480.99 698.89≤x≤766.23 99% confidence limit 415.82≤x≤489.84 688.31≤x≤776.81 3.2. moisture content the minimum, maximum and average moisture content of ara after compression test is 8.84, 18.06 and 13.87 % while that of apado are 13.55, 19.76 and 15.71 %, respectively. this result is satisfactory, since it is less than the maximum recommended moisture content of 20 % for an air-dried sample. at this moisture content the likelihood of decay of the timber is greatly reduced. table 3: average moisture content of ara and apado specie average moisture content (%) ara apado minimum 8.84 13.55 maximum 18.06 19.76 mean 13.87 15.71 standard deviation 7.53 9.84 cov (%) 35.43 42.68 95% confidence limit 9.20≤x≤18.54 9.61≤x≤21.81 99% confidence limit 7.74≤x≤20.00 7.70≤x≤23.73 3.3. stress-strain relationship of ara and apado timber the continuous column design equations of stress-strain relationship of ara and apado timber species was obtained from the regression analysis as given in equation (9) and (10), respectively. the continuous equations are as follows: 𝜎 = 47.882−0.009λ (9) 𝜎 = 17.211−0.007λ (10) table 4 presents the relationship that exist between the timber species stress, strain, slenderness ratio and young’s modulus. the stress at which a column buckles decreases as slenderness ratio increases and the mean length increases as well. table 4: slenderness ratio, stress @ yield and young’s modulus relationship for ara and apado mean height (mm) mean slenderness ratio, λ mean stress @ yield, σ (n/mm2) young’s modulus (n/mm2) ara apado ara apado ara apado 200.67 13.91 14.21 37.32 37.10 1726.16 2020.66 402.67 27.82 28.63 41.89 30.04 1373.71 1594.56 600.67 41.44 42.52 37.25 22.79 1142.17 1036.18 802.67 54.93 58.27 38.79 28.49 1000.17 764.32 average 38.81 29.61 1310.55 1353.93 3.4. verification of design equations the relationship between experimental stress at yield and the theoretical stress using equation at yield for pterocarpus erinaceus (ara) and berlinia spp (apado) were both subjected to an analysis of variance (anova) test. the results of one-way analysis of variance (anova) on experimental stress at yield and jimoh a. a. and rahmon r. o. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 5 the theoretical value at 0.05 significance level is given in table 5 and 6 for ara and apado respectively. the pvalues that is 0.008087 and 0.008455 are both less than 0.05 which implies that there is significant differences between the experimental and theoretical values obtained. table 5: anova analysis for ara anova: single factor summary groups count sum average variance column 1 12 379.28 31.60667 18.20186 column 2 12 383.4997 31.95831 6.52446 anova source of variation ss df ms f p-value f crit between groups 0.741911 1 0.741911 0.06001 0.008087 4.30095 within groups 271.9895 22 12.36316 total 272.7314 23 table 6: anova analysis for apado anova: single factor summary groups count sum average variance column 1 12 347.08 28.92333 15.53202 column 2 12 350.6691 29.22242 12.08924 anova source of variation ss df ms f p-value f crit between groups 0.536723 1 0.536723 0.038863 0.008455 4.30095 within groups 303.8339 22 13.81063 total 304.3706 23 3.5. reliability analysis tables 7, 8, 9 and 10 show the reliability analysis of ara and apado timber species using constant failure rate model. the result of the reliability analysis as obtained from figure 2 and 3 shows that the timber species have reliability index of 0.64 and 0.63 (which is greater than 0.5, the minimum index for a reliable structure according to abdulraheem (2016), adedeji (2008) and ajamu (2014)) for a service life of 50 years, assuming other serviceability conditions are met. table 7: strength analysis of ara timber height (mm) average strength (σ) (n/mm2) cumulative strength (qi) (n/mm2) remaining strength (ri) (n/mm2) strength rate (di) 200 37.32 37.32 117.93 0.3164 400 41.89 79.21 76.04 0.3552 600 37.25 116.46 38.79 0.4898 800 38.79 155.25 0 1.0000 average strength rate, 𝑑 = 0.3164+0.3552+0.4898+1.0000 4 = 0.5404 failure rate, 𝜆 = 1−𝑑 𝑡 , assuming a service life of 50 years and that other serviceability conditions are met, the reliability of the ara timber column is evaluated as shown below using constant failure rate (cfr). 𝜆 = 1 − 0.5404 50 = 0.009192/𝑦𝑒𝑎𝑟 table 8: reliability using cfr time (years) 𝜆𝑡 𝑒 −𝜆𝑡 time (years) 𝜆𝑡 𝑒 −𝜆𝑡 0 0 1 140 1.287 0.2761 20 0.184 0.8319 160 1.471 0.2297 40 0.368 0.6921 180 1.655 0.1911 60 0.552 0.5758 200 1.838 0.1591 80 0.735 0.4795 220 2.022 0.1324 100 0.919 0.3989 240 2.206 0.1101 120 1.103 0.3319 260 2.389 0.0917 jimoh a. a. and rahmon r. o. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 6 figure 2: reliability of the ara timber table 9: strength analysis of apado timber height (mm) average strength (σ) (n/mm2) cumulative strength (qi) (n/mm2) remaining strength (ri) (n/mm2) strength rate (di) 200 37.10 37.10 81.32 0.4562 400 30.04 67.14 51.28 0.3694 600 22.79 89.93 28.49 0.4444 800 28.49 118.42 0 1.0000 average strength rate, 𝑑 = 0.4562+0.3694+0.4444+1.0000 4 = 0.5675 failure rate, 𝜆 = 1−𝑑 𝑡 , assuming a service life of 50 years and that other serviceability conditions are met, the reliability of the apado timber column is evaluated as shown below using constant failure rate (cfr). 𝜆 = 1 − 0.5675 50 0.008650/𝑦𝑒𝑎𝑟 table 10: reliability using cfr time (years) 𝜆𝑡 𝑒 −𝜆𝑡 time (years) 𝜆𝑡 𝑒 −𝜆𝑡 0 0 1 140 1.211 0.2979 20 0.173 0.8411 160 1.384 0.2506 40 0.346 0.7075 180 1.557 0.2108 60 0.519 0.5951 200 1.730 0.1773 80 0.692 0.5006 220 1.903 0.1491 100 0.865 0.4211 240 2.076 0.1254 120 1.038 0.3542 260 2.249 0.1055 figure 3: reliability of the apado timber 4. conclusions the overall conclusions emerging from this study are;  the average density of apado is higher than that of ara.  the moisture content in the timber species were both less than the saturated fibre moisture content which is 20 % which indicates that the timber was well seasoned before the test.  it was found that the maximum stress of ara timber is higher than that of apado, since ultimate stress of the material depends on its strength; hence ara timber is of higher strength compared to apado timber.  the continuous equation for ara timber was 𝜎 = 47.882−0.009𝜆 and that of apado timber was 𝜎 = 17.211−0.007𝜆.  the result of the reliability analysis shows that apa and apado timber have reliability index of 0.63 and 0.65 respectively for a service life of 50 years, assuming the design load limit is not exceeded. y = 0.9998e-0.009x r² = 1 0 0.2 0.4 0.6 0.8 1 1.2 0 100 200 300 r e li a b il it y time (year) y = 1e-0.009x r² = 1 0 0.2 0.4 0.6 0.8 1 1.2 0 50 100 150 200 250 300 r e li a b il it y time (year) jimoh a. a. and rahmon r. o. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 7 reference abdulraheem, k. k. (2016): reliability index assessment of solid and laminated teak wooden deep i-beam for residential building. m. eng. thesis report submitted to the department of civil engineering, faculty of engineering and technology, university of ilorin, nigeria, 1 115. adedeji, a. a. (2008): reliability-based probability analysis for predicting failure of earth brick wall in compression. nigerian journal of construction technology and management, 9(1): 25 – 34. aguwa, j. i. (2010): reliability studies on the nigerian timber as an orthotropic, elastic structural material. a ph.d. thesis submitted to postgraduate school, federal university of technology, minna, nigeria, 1 – 153. aguwa j. i. (2011): structural reliability analysis of the nigerian ekki timber bridge beam subjected to deflection under the ultimate limit state of loading. presented and published in the book of proceedings, 2nd biennial engineering conference, , 311 318. aguwa, j. i. (2012): reliability assessment of the nigeria apa (afzelia bipindensis) timber bridge beam subjected to bending and deflection under limit state of loading. international journal of engineering and technology, 2(6): 1076 1087. aguwa j. i. and sadiku s. (2011): reliability studies on the nigerian ekki timber as bridge beam in bending under the ultimate limit state of loading. journal of civil engineering and construction technology (jcect), 2(11): 253-259. aguwa, j. i., chukwu, p. c. and auta, s. m. (2015): characterization and grading of south eastern nigeria grown irvingi a gabonensis timber in accordance with bs 5268. usep: journal of research information in civil engineering, 12(2): 720-731. ajamu, s. o. (2014): optimal design of cement-lime plastered straw bale masonry under vertical load and thermal insulation for a residential building, ph. d thesis report submitted to the department of civil engineering, faculty of engineering and technology, university of ilorin, nigeria, 1 – 128. apu, s. s. (2003): wood structure and construction method for low-cost housing. international seminar/workshop on building materials for low-cost housing, indonesia, 7 28. british standard, bs 373 (1957): methods of testing small clear specimens of timber, british standards institution, 2 park street, london wia 2bs. british standard, bs 5268 (2002): the structural use of timber part 2; for permissible stresses, materials and workmanship, 5th edition british standards institution, 2 park street, london wia 2bs, 176. british standard european standard, bs en 408 (2003): timber structures – structural timber and glue-laminated timber – determination of some physical and mechanical properties. london: british standard institution, 1 – 33. jamala, g. y., olubunmi, s. o., mada, d. a. and abraham, p. (2013): physical and mechanical properties of selected wood species in tropical rainforest ecosystem, ondo state, nigeria. karlsen g. and slitskouhov y. u. (1989): “wooden and plastic structures” 1st edition, mir publishers moscow, ussr, 400. kliger r. (2006): moisture effects on building and structural timber. chalmers university of technology, building and environmental engineering, steel and timber structures. se-412 96 goteborg sweden, 1 – 30. leitch, r. d. (1988): basic reliability engineering analysis, 1st edition, mcginley, 13 86. nigerian standard code of practice, ncp 2 (1973): the use of timber for construction, nigerian standards organisation, federal ministries of industries, lagos, nigeria, 2 71. nowak, a. s. (2004): survey of textbooks on reliability and structure, report on the special project sponsored by the structural engineering institute of asce. porteous, j. and kermani, a. (2007): structural timber design to eurocodes. blackwell publishing, usa. rahmon, r. o., jimoh, a. a., babatunde, o. y. and tazou, o. l. (2017): strength characteristics and grading of eku (brachystegia eurycoma) timber grown in kwara state, nigeria in accordance to bs 5268. usep: journal of research information in civil engineering, 14(4): 1891 1905. raw materials research and development council, rmrdc (1998): local building and construction materials, 27-39. thelandersson s. (2003): introduction: safety and serviceability in timber engineering. in thelandersson s. and larsen h.j. (eds) timber engineering, john wiley and sons ltd, the atrium, southern gate, chichester, west sussex, england. 22 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper extraction of papain from papaya (carica papaya l.) fruit latex and its application in transforming tannery raw trimming olyad erba urgessa1,*, duguma dibbisa itana1, tamiru oljira raga 2 1school of biological sciences and biotechnology, haramaya university, p.o.box:138, dire dawa, ethiopia 2ethiopian institute of biotechnology, addis ababa, ethiopia * corresponding author, e-mail: olyaderba@gmail.com abstract the leather industry is one of the major polluting industries in ethiopia. environment protection has prompted industrialists and scientists to re-look at transformation of tannery solid waste materials to valuable products using enzymatic hydrolysis. acid and liming process of gelatin production generate large amount of wastes and used limited raw materials. this study, therefore, aimed to extract papain from papaya fruit latex and use it for transforming raw trimming to gelatin. extraction and purification was carried out using three phase partitioning (tpp). protein content and protease activity were determined using lowry and casein hydrolysis method, respectively. effect of agitation time, crude extract to t-butanol ratio, ammonium sulphate concentration and temperature on purification fold and activity recovery of papain was evaluated and process was optimized. at its optimized parameters, the intermediate phase of tpp showed 94.14 % of protease activity recovery and 8.31 purification fold. at its optimized parameters, bottom phase showed 75.15% percentage of protease activity recovery and 6.61 purification fold. enzymatic hydrolysis of raw trimming produced 68% and 64% (weight by weigh) gelatin recovery from the use of crude and intermediate phase papain, respectively. relatively low gel strength of gelatin with bloom value of 95 g and 87 g were obtained from hydrolysis of raw trimming by intermediate and crude papain, respectively. this study showed that the use of crude extract for transforming raw trimming to gelatin was found good as it showed comparable protease activity. the tpp can be implemented for the extraction and purification of proteases from papaya fruit for industrial application that requires it in partial pure form. keywords: gelatin; optimization; papain; papaya latex; tannery waste. 1. introduction the leather industry is one of the major polluting industries in ethiopia since it generates large amount of liquid and solid wastes (solomon, 2011). tanning is the process of converting raw hides and skins into imputrescible substance. the reduction, leveling and purification operations generate untanned and tanned proteinous wastes. these solid wastes pose major environmental problem if not managed effectively (sundar et al., 2011). it releases obnoxious smell because of degradation of proteinous molecules of skin and emits greenhouse gases such as nh3, h2s, ch4 and co2 (solomon, 2011). therefore, stringent enforcement of the environment protection has prompted industrialists and scientists to re-look at the decontamination of wastes and transform tannery solid waste materials to valuable products (sundar et al., 2011). conventional chemical-thermal process of solid waste treatment from the tannery industry needs high amounts of energy and consumes much time. an alternative enzyme treatment process is more favorable in terms of environment protection and can be carried out at low cost of energy and temperature. furthermore, http://www.ejssd.astu.edu/ olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 23 protein products obtained can be used as fertilizers or for other agricultural purposes (sundar et al., 2011). gelatin is used in many traditional applications such as in the food, pharmaceutical, photographic, and cosmetic industries. the enzymatic hydrolysis of several natural materials has been extensively studied and several substantial yield improvements of gelatin has achieved (guerard et al., 2001; park et al., 2001). in gelatin manufacturing industry, the major source of raw material comes from the tannery industry. rawhide is the treated split of large animals (after fleshing) such as cows and buffalos used as raw materials. it is composed of a large amount of structural fibrous proteins called collagen. acid and liming gelatin production processes have several disadvantages, especially large amount of wastes generated and the type limitation of raw materials (damrongsakkul et al., 2007). proteolytic enzymes from plant latexes receive added attention due to broad substrate specificity and activity in wide range of ph and temperature, and in presence of organic compounds and other additives (tomar, 2008). unripe green papaya fruit as well as other part of papaya tree is concentrated with latex, which is composed of several valuable enzymes: papain, chymopapain, caricain and glycyl endopeptidase. to make industrially useable state, these enzymes need to extracted and purified from green papaya fruits. it is crucial to isolate and purify papain in the native crystalline state from fresh latex (paul et al., 2013). for isolation and purification of papain, aqueous two phase system (nitsawanget al., 2006; li et al., 2010) and tpp system has been reported as common method. but, tpp is a simple, inexpensive and easily scalable technique which can be directly used with crude suspensions (vetal and rathod, 2015). so far, the application of tpp for the purification of papain enzyme from papaya fruit latex and the enzymatic hydrolysis of solid protein waste of tannery by the extracts are rarely found in the literature. therefore, this study aimed to extract papain from fruit latex using tpp and utilize it for transforming raw trimming waste from tannery to gelatin. 2. methods and materials 2.1. latex extraction and collection the latex of papaya was collected and extracted as described by rathi and gadevar (2007). unripe matured fruit was tapped early in the morning and finished by mid-late morning. vertical cut of 1-2 mm deep was made using a stainless steel knife. a plastic dish was used to collect the latex. the latex was then scraped into a polythene lined box with a close fitting lid. latex adhering to the fruit was carefully scraped off and transferred to the collecting box using plastic spoon. collected latex was mixed with potassium metabisulphite (kms) (k2s2o5) by ratio of 0.5% w/w. 2.2. latex drying and storage latex was dried as described by puig et al. (2008). collected latex was arranged in aluminum trays and dried in a tray drier at 40°c, 746.6 mbar pressures for 2hr. after drying, the latex was transferred to a plastic bottle and stored at −20°c until used for analysis (nitsawang et al., 2006). 2.3. preparation of crude papain and three phase partitioning preparation of crude papain and three phase partitioning was carried out following modified methods of vetal and rathod, (2015). crude papain was prepared by dissolving 10 g of thawed latex in 100 ml of 0.1 m phosphate buffer of ph 7. the homogenate was filtered through whatman no.1 and was centrifuged at 5,000 rpm for 30 min. after centrifugation supernatant was collected and analyzed for protein content and activity, while pellet was discarded. for three phase partitioning, 10 ml of crude papain was added into 50 ml flask, mixed with 10 ml t-butanol followed by addition of 8 g of ammonium sulfate (= 40%, w/v) at 45°c. then, the ph of mixture was adjusted to 7 and stirred at 200 rpm for 100 min and was centrifuged at 5000 rpm for 20 min to facilitate the separation of phases. finally, mixture was kept at room temperature in a separating funnel for 1hr for phase separation. three distinct phases was carefully observed and separated. upper phase was discarded while intermediate and bottom phase was used for further study. the intermediate phase was dissolved in 0.1 m phosphate buffer of ph 7 by ratio of 1:0.5 (v/v), respectively. protein content, enzyme activity, purification fold and percentage activity recovery were determined for the phases. olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 24 2.4. measurement of protein content concentration of the protein was determined by lowry assay using folin reagent (lowry et al., 1951). papain extract samples solution were mixed well using vortex and 1.5 ml of the sample solution was transferred to 10 ml capacity centrifuge tubes. then, 2.2 ml of fresh lowry solution was added to each sample tubes and the solution was mixed gradually decreasing the speed of vortex. after 20 min incubation at room temperatures in dark, 0.3 ml of 0.5 mm of folin reagent was added to each tube and mixed immediately using vertex. the solutions were incubated for 30 min at room temperatures in dark. then, the solutions were mixed briefly using vortex and 4ml of each was transferred to cuvette. the absorbance was measured at 660 nm. bovine serum albumin (bsa) was used as standard. the stock solution of 10 mg/ml was prepared using buffer solutions. the stock was diluted to 0.5, 1, 1.5, 2, 2.5 mg/ml concentrations. 2.5. measurement of protease activity assay for protease activity was conducted using protocol described by cupp-enyard (2008). five ml of 0.65% casein solution was added into 15 ml capacity sample and blank test tube, and equilibrated in a water bath at 37°c for 5 min. then, 500 µl papain extract sample solution was added to the sample test tube, but not to the blank test tube. the solution was mixed by swirling and incubated for 37°c for 10 min. after incubation, 500 µl of the papain extract sample was added into the blank test tube and simultaneously, 5 ml of the trichloroacetic acid (tca) solution was added into both test tubes to stop the reaction. the reaction solutions were incubated for 30 minutes. after incubation, 2 ml of the solution was filtered using filter paper into centrifuge tubes of 10 ml capacity. thereafter, 5 ml sodium carbonate was added into centrifuge tubes and mixed by swirling followed by immediate addition and mixing of 1ml folin’s reagent. then, the tubes were incubated at 37ºc for 30 min. the absorbance of the sample solutions was measured by a spectrophotometer using a wavelength of 660 nm. tyrosine was used as standard and its stock solution (10 mg/ml) was prepared using buffer solution. the stock was diluted to 200 µg/ml, 400 µg/ml, 600 µg/ml and 800 µg/ml concentrations. one protease unit was defined as the amount of casein hydrolyzed to produce color equivalent to 1.0 μmole (181 μg) of tyrosine per min at ph 7 and 37°c (color by folin and ciocalteu’s reagent) and was calculated as: where vt is the total assay volume in ml, ve is the volume of the enzyme used ml, t is the reaction time taken in min, and vc is the volume used in the colorimetric reaction in ml. after determination of protein content and protease activity, activity recovery percentage and purification fold were calculated using the following equations. where specific activity was calculated using equation: 2.6. process optimization process optimization of three phase partitioning for crude papain was considered agitation time taken, crude extract to t-butanol ratio, ammonium sulphate concentration and temperature parameters. first, the effect of agitation time taken was determined according to vetal and rathod, (2015). optimization of time taken was done by varying it from 60 to 100 min at interval of 10 min. the experimental parameters were as follows: 1:1 ratio of crude extract to t-butanol, (40% w/v) ammonium sulphate solution, ph 7 buffers, 45°c, 200 rpm agitation speed. the agitation time taken that gave the highest protease activity recovery was chosen for further study. second, the effect of ratio of crude papain extract to t-butanol was determined by methods described by chawuit et al. (2010). optimization of t-butanol ratio was done by varying it from 0.5 to 1.5 ml at interval of 0.25 ml. the experimental parameters used were the ratio of crude papain extract to t-butanol of 1:0.5, 1:0.75,          t g c μmol of tyrosine vunits ml of enzyme v t v  protease activity of the phase papain activity recovery percenatge 100 protease activity of the crude papain x        specific activity of the phase papain purification fold specific activity of the crude papain        protease activity of the sample papain extract specific activity protein content of the sample papain extract        olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 25 1:1, 1:1.25, and 1:1.5 (v/v), (40% w/v) ammonium sulphate , ph 7 buffer , 45°c , 200 rpm agitation speed and optimized agitation time. the ratio of crude papain extract to t-butanol that gave the highest protease activity recovery was chosen for further study. third, the effect of ammonium sulfate concentration was determined by methods described by chawuit et al., (2010). optimization ammonium sulfate concentration was done by varying it from 30 to 50 % at interval of 5. the experimental parameters were as follows: 45°c temperature, ph 7 buffer, 200 rpm agitation speed, optimized agitation time taken and ratio of crude papain extract to t-butanol. the ammonium sulfate concentration providing the highest protease activity recovery was chosen for further study. fourth, the effect of temperature was investigated. the optimization of temperature was done by varying it from 45 to 85°c (pitpreech and damrongsakkul, 2006) at interval of 5. the experimental parameters were as follows: ph 7 buffer, 200 rpm agitation speed, optimized agitation time, ratio of crude papain extract to t-butanol and ammonium sulfate concentration. the temperature providing the highest protease activity recovery was chosen for purification fold and enzyme activity recovery of optimized process. 2.7. enzymatic hydrolysis of proteineous tannery waste gelatin production was carried out as described by pitpreecha and damrongsakkul (2006). raw trimming waste was obtained from modjo tannery sharing company. the trimming was washed, dried and ground. slurry was prepared by dissolving 75 g of ground raw trimming in 300 ml of phosphate buffer (ph = 7.0) by 1:4 (w/v) ratio. the solution was well mixed and the formed slurry was then heated to 75 °c temperature. then, 0.035 ml of intermediate and crude papains was mixed with 100 ml of slurry. this enzymatic hydrolysis reaction mixture was heated at 75°c for 90 min. then, reaction mixture was heated to 90°c for 15 min to deactivate enzyme, centrifuged at 9000 rpm for 5 min and filtered to separate gelatin solution from residue. protein concentration of filtered gelatin solution was measured and percentage of gelatin recovery was calculated based on the following equation: table 1: the process of three phase partitioning optimization independent factor optimization order independent factor values controlled factors value 1. agitation time (min) 60, 70, 80, 90, 100 crude extract: t-butanol = 1:1 (v/v) (nh4)2so4 = 40% (w/v) t0 = 45 oc ph = 7 speed = 200 rpm 2. crude extract: t-butanol (v/v) 1:0.5, 1:0.75, 1:1, 1:1.25, 1:1.5 optimized agitation time (nh4)2so4 = 40% (w/v) t0 = 45 oc ph = 7 speed = 200 rpm 3. (nh4)2so4 (w/v %) 30, 35, 40, 45, 50 optimized agitation time optimized crude extract: t-butanol (v/v) t0 = 45 oc ph = 7 speed = 200 rpm 4. temperature (oc) 45, 55, 65, 75, 85 optimized agitation time optimized crude extract: t-butanol (v/v) optimized (nh4)2so4 (w/v %) ph = 7 speed = 200 rpm olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 26 where, pg is protein concentration of gelatin solution in g/ml, pf is protein fraction of raw trimming 0.6362 (pitpreech, 2006), w is the weight (g) of raw trimming powder used to make slurry and v is the volume (ml) of buffer used to dissolve the raw trimming powder for slurry formation. the left gelatin solution was dried for yield and gel strength measurement. gel strength of gelatin was determined according to pitpreecha and damrongsakkul (2006) and damrongsakkul et al. (2007). the dried gelatin was dissolved in distilled water making concentration of 12.5% gel (w/v) at 60°c. the solution was cooled at 4°c (maturation temperature) for 16 hrs. the gel strength of gelatin was determined by using a texture analyzer, equipped with 1.27 cm diameter hemisphere head cylindrical at a cross-head speed of 0.8 mm/s. the force required was measured at the center of gel surface vertically to a depth of 4 ± 0.01 mm. the measured gel strength was in the double bloom standard. yield was determined according to mad-ali et al. (2016). 2.8. data analysis all the experiments were performed in triplicate. the data was expressed as mean ± standard deviation. the significance differences of the different factors was evaluated by analysis variances (anova) using spss version 20. a single factor anova was used for the statistical analysis. the p-value less than 0.05 (p ˂ 0.05) considered to be statistically significant. 3. results and discussion 3.1. enzymatic activity of crude papain and two phase of tpp the preliminary three phase partitioning was conducted at parameters of 1:1 ratio of crude extract to t-butanol, at 40 % ammonium sulfate saturation, 45°c, ph = 7 and at 200 rpm agitation for 100 min and crude papain was extracted from the papaya fruit latex by using phosphate buffer at ph=7. three phase partitioning uses t-butanol and ammonium sulfate to precipitate enzymes and proteins from aqueous solution. tertiary butanol is having complete miscibility with water, but after addition of ammonium sulfate, its solubility changes, forming top t-butanol layer, middle enzyme/protein precipitate layer and bottom aqueous layer (pike and dannison, 1989; kalyani et al., 2006). the target enzymes get partitioned into either of phases depending upon its molecular properties and operational conditions (pike and dannison, 1989). t-butanol is also played role in removing some small molecular weight contaminant compounds such as lipids, phenolics and some detergents (roy and gupta, 2001). the result of the study showed that protein content of crude extract was significantly higher than that of both phase of tpp at initial and optimum parameters. additionally, protease activity of crude extract was higher than that of both phases of tpp at initial and optimum parameters, but not significantly different (p > 0.05) (table 2). higher protease activity of crude extract is might be due to maintaining of ph of the solution and impact of t-butanol. it was reported that the phosphate buffer efficiently maintained the system ph (chaiwut et al., 2010). generally, many studies showed that tbutanol does not cause denaturation of the partitioned enzyme as it is unable to permeate inside the folded three dimensional structure of protein due to its larger molecular size. however, it was reported that some enzymes may lose their activity in the presence of high amount of t-butanol (gagaoua and hafid, 2016) and that t-butanol can also inhibit activities of some enzymes (dannison et al., 2000). the study result showed that optimized parameters of three phases partitioning for intermediate phase were 90 min agitation time, 1:1.5 crude extract to t-butanol ratio, 50% ammonium sulphate concentration at 65°c and for bottom phase were 80 min agitation time, 1:0.75 crude extract to t-butanol ratio, 30% ammonium sulphate concentration at 75°c. at optimized parameters, protease activity recovery and purification fold (94.14%, 8.31), respectively, of intermediate phase were higher that of bottom phase protease activity recovery and purification fold (75.15%, 6.61), respectively (table 2). a different trend was reported by chaiwut et al. (2010). they reported that at optimized first tpp with 20% (w/v) (nh4)2so4 pg percentage of gelatin recovery 100 w pf v             weight of dried gelatin solution g yield % 100 weight of raw trimming powder g   olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 27 and 1:0.5 ratio of extract to t-butanol, papaya fruit peel bottom phase showed higher purification fold and activity recovery (15.8, 253.5%) , respectively, than that of intermediate phase purification fold and activity recovery (4, 4%), respectively. the difference might be due to different papaya part used for protease extraction, and chemical structure and composition of protease papaya peel and fruit latex. chaiwut et al. (2010) obtained most proteases from papaya peel extract partitioned in the aqueous phase of tpp while in present study in intermediate phase of fruit latex extract. this implied the difference in chemical structure and composition of cystein protease from peel and latex. 3.2. three phase partitioning process optimization three phase partitioning (tpp) is affected by various process conditions, such as ammonium salt concentration and ratio of crude enzyme extract to tbutanol (chaiwut et al., 2010; duman and kayan, 2013 and 2014; kulkarni and rathod, 2013; vetal and rathod, 2014), temperature (chaiwut et al., 2010; kulkarm and rathod, 2013), ph (duman and kayan, 2013; kulkarni and rathod, 2013; vetal and rathod, 2014), agitation time (vetal and rathod, 2014). in this study, different values or intervals of ammonium salt concentration, ratio of crude enzyme extract to tbutanol, agitation time was investigated. the effects of these parameters on purification fold and activity recovery of papain purified by tpp from fruit latex were given in figure 14. as purification fold and activity recovery are very important to determine the optimum parameter at which tpp system works best for the purification of enzymes, they were put on y-axis of the same graph for each independent factors affecting tpp. in this study, in order to determine the best tpp system for the purification of papain, the parameters that gave the highest % activity recovery and purification fold was considered for stepwise optimization process. 3.2.1. effect of agitation time on protease purified by tpp agitation time is one of the key factors as far as economy of the process is concerned. time taken required for completion of any industrial reaction or process should be the minimum to make it economically feasible (vetal and rathod, 2014). hence, agitation time was optimized to get maximum possible activity recovery and purification fold in small possible duration. as shown in figure 1, optimization of time was done by varying it from 60 to 100 min and keeping other experimental parameters constant. the result of study showed that highest protease activity recovery and purification fold of papain was occurred at 80 min and 90 min for bottom and intermediate phase, respectively. activity recovery (94.4%) and purification fold (6) were obtained for intermediate phase while activity recovery (84.2%) and purification fold (4.7) were obtained for bottom phase, respectively. a higher purification fold (12.14), but lower activity recovery (71.43%) was reported for peroxidase extracted from orange peel (vetal and rathod, 2014). as saturation was achieved in 80 min for bottom phase and 90 min for intermediate phase, they were selected as optimum time for the subsequent experiments. table 2: enzymatic parameters of different extracts of papain from papaya fruit latex extraction steps product protease activity (u/ml) protein content (mg/ml) specific activity (u/mg) activity recovery(% ) purification fold crude crude 11.88x10-2 ± 0.06a 16.44 ± 3.02d 7.68x10-3 ± 0.01a i-tpp i-phase 8.86x10-2 ± 0.06a 10.44 ± 1.34c 8.12x10-3 ± 0.00a 71.42 ± 6.03a 1.12 ± 0.12a b-phase 7.56x10-2 ± 0.03a 7.26 ± 0.59b 10.50x10-3 ± 0.00a 67.70 ± 7.77a 1.59 ± 0.41a o-tpp i-phase 11.14x10-2 ± 0.05a 2.10 ± 0.89a 68.03x10-3 ± 0.06a 94.14 ± 1.16b 8.31 ± 1.15b b-phase 8.47x10-2 ± 0.03a 2.02 ± 0.82a 47.80x10-3 ± 0.03a 75.15 ± 7.46a 6.61 ± 1.38b i-tpp is three phase partitioning at initial parameters and o-tpp is at optimized parameters. i is intermediate and b is bottom. the numbers are in mean and standard deviation. letter compares means in the column. means with different letters are significantly different at p < 0.05. olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 28 figure 1: the effect of time on activity recovery and purification fold of papain from papaya fruit latex 3.2.2. effect of crude extract to t-butanol on protease purified by ttp the effect of t-butanol volume that was required for protease partitioning by tpp was shown in figure 2. the ratio of the crude extract to t-butanol was varied from 1:0.5, 1:0.75, 1:1, 1:1.25 and 1:1.5 (v/v) with a constant of 40% (w/v) (nh4)2so4 saturation. the highest protease activity recovery (92.6%) and purification fold (5.7) were obtained from the intermediate phase at 1:1.5 ratios. for bottom phase, the highest protease activity recovery (66.7%) and purification fold (4.1) were obtained at 1:0.75 ratios. a similar highest protease recovery (67.3%) and a different purification fold (2.4) were reported for bottom phase from papaya peel at ratio of 1: 0.5 (chaiwut et al., 2010). the result of this study showed that an increase in t-butanol volume decreases the activity recovery and purification fold in the bottom phase. chaiwut et al. (2010) were reported similar trend and described that if the t-butanol content is high (>1:1), the denaturation of the protein is more likely. for intermediate phases, an increase of t-butanol volume resulted in increase of activity recovery and purification fold. in supporting this result, vetal and rathod, (2014) found that increased amount of t-butanol increased salt concentration in aqueous phase causing precipitation of enzyme at intermediate phase. the ratio of crude extract to t-butanol of 1:0.75 and 1:1.5 were selected for bottom and intermediate phase, respectively, for investigating the effect of (nh4)2so4 concentration. figure 2: the effect of ratio of crude extract to t-butanol on activity recovery and purification fold of papain from papaya fruit latex 3.2.3. effect of ammonium sulfate concentration on protease purified by tpp ammonium sulfate concentration plays a major role in tpp as it is responsible for protein–protein interaction and precipitation. it causes protein precipitation by salting out mechanism. protein solubility is influenced by the ionic strength of the solution which subsequently depends on salt concentration. on addition of sufficient salt, proteins precipitation occurs. this is known as salting out effect (narayan et al., 2008; chaiwut et al., 2010; vetal and rathod, 2014). in this study, the effect of (nh4)2so4 was studied by varying the concentration of (nh4)2so4 from 30 to 50% (w/v). it was indicated that minimum salt concentration to starts with for optimization of tpp is 30% (w/v) so as to obtain the maximum amount of the desired protein in the interfacial precipitate (chaiwut et al., 2010). this study result showed that at the concentration of 50% (nh4)2so4, the highest protease activity recovery (104.5%) and the highest purification fold (5.8) were obtained for intermediate phase, and the highest protease activity recovery (97.7%) and the highest purification fold (4.4) were obtained for bottom phase at (30%) (figure 3). opposing present result, most proteases from papaya peel extract partitioned in the aqueous phase of tpp and the highest protease recovery (121.4%) and the highest purification fold (5.4) at concentration of 20% (nh4)2so4 were reported in the bottom phase of the tpp system (chaiwut et al., 2010). olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 29 in this study, increasing % (nh4)2so4 concentration resulted in an increase of protease activity recovery and purification fold for intermediate phase and a decrease of protease activity recovery and purification fold for bottom phase. similar trend has been reported by chaiwut et al. (2010) in the extraction of protease from papaya peel for both phases. in line with this, it was reported that at higher salt concentration, water molecules are attracted by salt ions result in stronger protein–protein interactions and the protein molecules coagulate through hydrophobic interactions at intermediate phase (narayan et al., 2008; chaiwut et al., 2010; vetal and rathod, 2014). as maximum activity recovery and purification fold was achieved at 50% (nh4)2so4 concentration for intermediate phase and at 30% (nh4)2so4 for bottom phase, 50% and 30% (nh4)2so4 selected as optimum value for temperature optimization. figure 3: the effect of ammonium sulfate concentration on activity recovery and purification fold of papain from papaya fruit latex 3.2.4. effect of temperature on protease purified by tpp temperature is an important parameter that affects the enzyme configuration and overall stability (vetal and rathod, 2014). effect of temperature was studied by varying water bath temperature from 45 to 75 °c. this temperature was selected considering appropriate temperature for gelatin production. other parameters were kept at optimized value. figure 4 illustrated the effect of temperature on partitioning behavior of papain in tpp. activity recovery and purification fold of the intermediate phase enzyme was increased with an increase in the temperature from 45°c to 65°c. at 65 °c temperature, maximum activity recovery (97.7%) and purification fold (4.9) were found. for bottom phase, maximum activity recovery and purification fold was increased with an increase in the temperature from 45°c to 75°c. at 75 °c temperature, maximum activity recovery (96.0%) and purification fold (4.5) were found. decrease in activity recovery and purification fold at higher temperature (above 65 and 75 °c for intermediate and bottom, respectively) was may be thermal deactivation of enzymes. in line with this, chaiwut et al. (2006) reported that papaya peel and latex protease showed good stability to temperatures up to 70 °c and latex protease activity decrease rapidly at temperature > 80 °c. figure 4: the effect of temperature on activity recovery and purification fold of papain from papaya fruit latex 3.3. enzymatic hydrolysis of raw trimming the hydrolysis of raw trimming was carried out using the optimized temperature and time parameters by pitpreecha and damrongsakkul (2006). the crude extract and optimized intermediate phase papain was used for enzymatic hydrolysis of raw trimming. the gel yield, recovery and strength of gelatin obtained from hydrolysis of raw trimming by crude papain and intermediate phase is depicted in figure 5. from the hydrolysis reactions, percentage of gelatin recovery from crude extract (crude papain) hydrolysis was 68 wt%. in the case of optimized intermediate phase papain, the percentage of gelatin recovery was 64 wt%. olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 30 the higher gelatin recovery percentage for crude papain was may be due to the higher rate of enzyme hydrolysis reaction. compared to present study, pitpreecha and damrongsakkul (2006) reported a higher 72 wt% and 71 wt% of gelatin recovery from hydrolysis of raw hide using crude papaya latex extract and commercial papain respectively, at 75 °c. similarly, damrongsakkul et al. (2007) reported significantly higher gel recovery of (85 wt %) gelatin produced by hydrolysis of raw hide using papain, ec 3.4.22.2, (0.51 unit/mg). gelatin extraction yield (on dry basis) from both hydrolysis of raw trimming by crude and intermediate phase papain were expressed as the weight of dried gelatin solution (g) with respect to the weight of dried powder of raw trimming (g). the amount of gelatin extracted by using crude papain was similar with amount of gelatin extracted by using intermediate phase. figure 5: gelatin yield, recovery and strength from hydrolysis of raw trimming hydrolysis of raw trimming by crude papain resulted in a lower gel strength (bloom value of 87 g) as compared to the gel strength of gelatin produced by intermediate (bloom value of 95 g). this was due to a higher protease activity of crude papain. similar trend was reported by pitpreecha and damrongsakkul (2006) in which the lowest gel strength was observed at optimum temperature of 75 °c at which enzyme activity is the highest. gelatin with higher molecular weight showed greater bloom value was reported by du et al. (2014). pitpreecha and damrongsakkul (2006) described that at the condition for highest enzyme activity, short chain gelatin or low molecular weight gelatin was obtained from the hydrolysis whereas, high molecular weight gelatin could be obtained from the hydrolysis at the condition corresponded to low enzyme activity. 4. conclusion proteolytic enzymes contained in papaya fruit latex can be simply extracted using phosphate buffer ph 7 as the activity of crude papain was greater than that of papain purified by three phase partitioning (tpp). the extraction and purification of papain at optimized parameters of tpp increased activity recovery and purification fold of papain from 71.42% to 94.14% and 1.12 to 8.31, respectively, for intermediate phase. as well as, increment in activity recovery and purification fold of papain for bottom phase was from 67.70% to 75.15% and 1.59 to 6.61, respectively, at optimized parameters of tpp. the gelatin recovery from both hydrolysis reactions is related to the gel strength of the obtained gelatin. the gel strength of the obtained gelatin from both hydrolysis reactions was relatively low. the results of hydrolysis of raw trimming tannery waste indicated that crude papain proteolysis could be used to produce gelatin from raw trimming. as well as the intermediate phase could be used alternatively in production of gelatin incase purity is needed. acknowledgements this paper is part of haramaya university research grant coded hurg-2016-06-01-05. therefore, haramaya university, office of vice president for research affairs deserves gratitude for this research project grant. reference chaiwut, p. pintathong, p., & rawdkuen, s. 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(2008). a stable serine protease, wrightin, from the latex of the plant wrightia tinctoria (roxb.). r. br.: purification and biochemical properties. journal of agricultural food chemistry. 56(4), 1479– 87. doi: 10.1021/jf0726536. http://dx.doi.org/10.1016/j.pep.2013.08.003 http://dx.doi.org/10.1016/s1381-1177(00)00031-x http://dx.doi.org/10.1016/j.indcrop.2013.10.032 http://dx.doi.org/10.57613/ajas.15.0784 https://doi.org/10.1002/bit.260330213 https://doi.org/10.1021/jf0726536 olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 32 vetal, m. d. & rathod, v k. (2014).three phase partitioning a novel technique for purification of peroxidase from orange peels (citrus sinenses). food and bio-products processing, 94, 284–289. vetal, m. d. & rathod, v k. (2015).three phase partitioning a novel technique for purification of peroxidase from orange peels (citrus sinenses).food and bio-products processing, 94: 284–289. 153 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 physicochemical characteristics analysis in niger seed edible oil (adama) and linseed edible oil (bishoftu) defaru negera school of applied natural science, applied chemistry program, adama science and technology university, adama p.o. box 1888, adama, ethiopia email: defarunegera@gmail.com abstract this study was directed towards the characterization of niger and linseed oil purchased from adama and bishoft respectively using official methods. the aoac method of analysis was employed in the determination of the chemical and physical properties of the oils. the chemical properties of the oils determined included the saponification value, acid value, peroxide value, soap content, copper (cu) (mg/kg) and iron (fe)(mg/kg), and insoluble impurities (%(m/m)). the physical properties of the oils determined were moisture content and volatile matter at 105 0 c (% (m/m)), refractive index at 40 0 c and relative density at room temperature. the values obtained were saponification values (192 & 189.17mgkoh/g), peroxide values (3.59 & 3.19 milliequivalent peroxide oxygen/kg oil), acid values (0.45 & 0.59 mgkoh/g), soap contents (0.001 & 0.005 (%( m/m)), copper (cu) (not detected mg/kg), iron (fe)(not detected mg/kg), insoluble impurities (0.01 & 0.02 %(m/m)), refractive indexes (1.4757 & 1.482 ), and relative density at room temperature (0.9220 and 0.929) for niger and linseed oil respectively. one proximate composition obtained was moisture content (0.09 & 0.15%). from the results obtained it can be concluded that niger and lin seed oils have huge potentials for use as domestic oils. keywords: niger seed, niger seed oil, linseed, linseed oil, characterization and proximate composition 1. introduction edible oils play an important role in the body as carriers of essential fatty acids (efa). efa are not synthesized in the body but are needed through the diet to maintain the integrity of cell membranes. they are also needed for the synthesis of prostaglandins which have many vital functions to perform in the body. based on maintenance of good diet and control health issues like diabetes mailto:defarunegera@gmail.com defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 154 © adama science & technology university https://ejssd.astu.edu.et it has been essential to consume authenticated edible oils. therefore, consumers need meaningful and honest information so that they can make an informed choice of their diet and the foods they purchase. to meet the quality and composition standards, oil and food industries use certain oil parameters to maintain the quality. protection against mislabeling and false description through legislation is an important part of food control. research to develop new analytical methods is likely to be an ongoing process but ever more difficult task as those who seek to gain financially, find increasingly sophisticated ways of food adulteration1. authenticity of edible oils and fats: according to uk and european legislation under sections 14 and 15 of the food safety act, it is an offence to sell food that is not of the nature, substance or quality demanded by the consumer or to falsely or misleadingly describes or presents food2. several factors affect the edible oil quality such as agronomic techniques, seasonal conditions, sanitary state of drupes, ripening stage, harvesting and carriage systems, method and duration of storage, and processing technology and it is determined by different analytical methods in order to assess the stability of oil and to avoid possible adulterations. the official methods for the determination of physicochemical parameters of edible oils, such as acidity and peroxide content are based on titration methods that are time-consuming and laborious. edible oil has always been and remains as a basic food item in ethiopia. the production of oil crops and the extraction of edible oil have always been and still are done mainly at the household level. commercial industrial scale oil extraction was introduced in the country at the beginning of the 20th century. the number and capacity of edible oil plants in the defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 155 © adama science & technology university https://ejssd.astu.edu.et country is not adequate enough to meet the domestic demand. according to the 2007 report on largeand medium-scale manufacturing and electricity industries survey of the csa, in 2005/6 the number of largeand medium-scale edible oil processing mills in the country is 33. out of these, 29 are under private ownership and the rest are publicly owned. the ethiopian government was aiming to achieve self-sufficiency in edible oil by 2015. the recently released fiveyear growth and transformation plan (gtp) underscores the importance of the agro-processing industry, which includes the edible oil sector. while the potential for and government commitment to self-sufficiency is there, domestic edible oil millers face a myriad of challenges related to input and technology. according to the ethiopian quality standard, all edible oil must be refined, although a number of specific oilseeds can be semi-refined (ethiopian quality standard requirements for edible oils). despite this requirement, many millers are selling crude oil particularly to the low-income class. most manufacturing industries require a uniform product quality. to ensure that this requirement is met, both raw materials and finished products are subjected to extensive chemical analysis. on the one hand, the necessary constituents must be kept at the optimum levels; while on the other impurities such as poisons in foodstuffs must be kept below the maximum allowed by law. the quality of fats and oils is dictated by several physical and chemical parameters that are dependent on the source of oil; geographic, climatic, and agronomic variables of growth in the case of plant oils as well as processing and storage conditions. thus, quality assurance criteria may depend partly on the defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 156 © adama science & technology university https://ejssd.astu.edu.et type of oil under investigation as well as on other factors that may vary depending on the intended use and regulations that vary from country to country1, 2, and 3. in general, one of the very important food products produced in ethiopia is edible oil. the demand of edible oil in the country is very high. on the bases of this, the government is attempting to increase the production to solve the problem in the country. fats and oils are one of the five necessary ingredients of human diet among protein, carbohydrates, minerals and vitamins. fats and oils quality analysis is the necessary step in the use of these ingredients. in this regard attention should be given about the quality of edible seed oils available on the market for consumption being extracted by small scale industries, e.g niger and lin seed oils extracted and on market in adama and bishoftu respectively. niger is an oilseed crop produced in ethiopia. its botanic name is guizotia abyssinia cass. among the ethiopian oilseed yield niger shares 50%. in ethiopia, niger has the ability to grow on wet soils. in this case niger seed has unique ability to be produced on wet soils where the majority crops and all other oilseeds fail to mature. it also gives an enormous measure to soil protection and land remedy1. human beings use niger seed as a food. 37-47% content of the seed is oil. the oil has a pale yellow colour with nutty taste and a pleasant odour4. the oil is readily subject to oxidative rancidation. the high content of unsaturated fatty acid causes its quality poor. its composition signifies (oleic acid 38% and linoleic acid 51.6%) confirming its unsaturation. the oil is used for cooking purposes, smoothing the body, manufacturing paints and soft soaps and for lighting and lubrication. the niger oil is good absorbent of fragrance of flowers defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 157 © adama science & technology university https://ejssd.astu.edu.et due to which it is used as base oil by perfume industry. niger oil can be used for birth control and treatment of syphilis. niger sprouts mixed with garlic and ‘tej’ are used to treat coughs. niger seed cake is a valuable cattle feed. it can also be used as manure. niger is also used as a green manure for increasing soil organic carbon5. the oil extracted from the seed of niger (noog) is the preferred food oil in ethiopia. the serving of food left over after the oil removal is free from any poisonous substance but contains additional crude fibre than other oilseed meals. the other important oilseed crop in the subtropics and temperate regions of the world is linseed linum usitatissimum l.6. this oil is used mostly for paints, varnish and other industrial uses. it is rich in linolenic acid and lignnan indicating, its potential as a highly nutritive source, both imparting multiple health benefits was well recognized7,8. linseed, after noug (guizotia abyssinica cass) is the second most important oilseed crop in the highlands of ethiopia9. 1. literature review 2.1. edible oils and fats: fats and oils are esters of glycerol, the simplest triol (trialcohol), in which each of the three hydroxyl groups has been converted to an ester. the difference between fats and oils is merely one of melting point: fats are solid at room temperature (20°c) while oils are liquids. both classes of compounds are triglycerides. oils are mainly unsaturated whereas fats are saturated. 2.2. chemical structure of lipids fats, oils and waxes are the naturally occurring esters of long straight-chain carboxylic acids. they belong to the “saponifiable” group of lipids. lipids are biologically produced materials which are relatively insoluble in defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 158 © adama science & technology university https://ejssd.astu.edu.et water but soluble in organic solvents (benzene, chloroform, acetone, ether, etc.). lipid is an ester of fatty acid and alcohol. if glycerol is alcohol the ester is known as triglyceride which almost constitutes oils and fats (lipids). if alcohol is a long chain of high molecular weight monohydroxy alcohol the ester is known as wax. r1oco r3oco ocor2 oils and fats ch3(ch2)12oco(ch2)14ch3 beewax 2.3. composition of lipids lipid is a solution; its solvent is the glycerides (saponifiable part) and its solute is non-glycerides (nonsaponifiable part). the nonsaponifiables (unsaponifiables) are that part of lipid which are not affected by alkali-hydroxides during saponification of lipid and can be extracted by organic solvents after saponification (as vitamins, sterols and resins). they are non-volatile on drying at 800c. it rarely exceeds 2%. the saponifiable parts (glycerides parts) are esters of fatty acids and glycerol which upon saponification with alkali gives glycerol and alkali salt of fatty acids (soap). it is the major part of lipid as it constitutes about 99% of lipid. therefore, the chemical and physical properties of lipids vary with variations of the glyceride part (fatty acid composition). 2.3.1. glycerides glycerol can be esterified commercially with one, two or three fatty acids to produce mono-, di-, or triglycerides. fats and oils are naturally occurring triglycerides. the properties of triglycerides depend on the fatty acid composition and on the relative location of fatty acids on the glycerol 2.3.2. saponifiable part (glycerides) the saponifiable lipids contain an ester group and react with hot sodium hydroxide defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 159 © adama science & technology university https://ejssd.astu.edu.et solution undergoing hydrolysis (saponification). 2.4. physical properties edible oils the physical properties, such as moisture and volatile matter, relative density and refractive index, depend on: the type of fatty acids present in the triglyceride and their location, chain length of fatty acids, and number and location of cis and trans double bonds on the fatty acid chains. 2.4.1. moisture and volatile matter moisture content of oils and fats is the loss in mass of the sample on heating at 105 ± 10c under operating conditions specified. the low moisture content of the oil is advantageous in terms of storage stability since the lower the moisture content, the better the storability. 2.4.2. relative density the density of fats and oils is an index of the weight of a measured volume of the material. the relative density at t/20°c of an oil or fat is the ratio of the mass in air of a given volume of the oil or at t °c to that of the same volume of water at 20 °c, the weightings being made with weights adjusted to balance weight in air. relative density, index of refraction tests are used to identify fats and oils. relative density means density with respect to water. it is the ratio of density of oil with that of water. 2.4.3. refractive index the refractive index of fats and oils is sensitive to composition. the refractive index of a fat increases with increasing chain length of fatty acids in the triglycerides or with increasing unsaturation. the refractive index can be utilized as a control procedure during hydrogenation processes. the ratio of the velocity of light in vaccum to the velocity defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 160 © adama science & technology university https://ejssd.astu.edu.et of light in the oil or fat or the ratio b/n the sine of angle of incidence to the sine of angle of refraction when a ray of light of known wave length (usually 589.3 nm, the mean of d lines of sodium passes from air to oil or fat. it varies with temperature and wave length. 2.5.chemical properties edible oil the chemical examinations of lipids involve reactions with ester linkage of the glycerides or free carboxylic acid, hydroxyl group of hydroxyl acids as well as the double bonds of the hydrocarbon chain of fatty acids, in order to differentiate between the different types of lipids, through determination of some chemical constants. 2.5.1. saponification value the saponification value is the number of mg of potassium hydroxide required to neutralize the free acids and to saponify the esters in 1 g of the substance. the saponification number is a measure of the average molecular weight of the triacylglycerols in a sample. saponification is the process of breaking down a neutral fat into glycerol and fatty acids by treatment with alkali. the smaller the saponification number the larger the average molecular weight of the triacylglycerols present i.e. saponification value is inversely proportional to the mean molecular weight of fatty acids (or chain length). it contains the information of the average molecular weight of all fatty acids present. the principle is boiling of a sample under reflux with ethanolic potassium hydroxide solution, followed by titration of the excess potassium hydroxide with standard volumetric hydrochloric acid solution. the analytical importance of saponification value is an index of mean molecular weight of the fatty acids of defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 161 © adama science & technology university https://ejssd.astu.edu.et glycerides comprising a fat. lower the saponification value, larger the molecular weight of the fat acids in the glycerides and vice-versa. 2.5.2. insoluble impurities the unsaponifiable matter is defined as the substances soluble in oil which after saponification are insoluble in water but soluble in the solvent used for the determination. it includes lipids of natural origin such as sterols, higher aliphatic alcohols, pigments, vitamins and hydrocarbons as well as any foreign organic matter nonvolatile at 100 e.g. (mineral oil) which may be present. 2.5.3. acid value and acidity the acid value (av) is the number that expresses, in milligrams the quantity of potassium hydroxide required to neutralize the free acids present in 1 g of the substance. the acid value may be overestimated if other acid components are present in the system, e.g. amino acids or acid phosphates. the acid value is often a good measure of the breakdown of the triacylglycrols into free fatty acids, which has an adverse effect on the quality of many lipids. acid value is the measure of hydrolytic rancidity. in general, it gives an indication about edibility of the lipid. the older an oil is the higher the acid value as triglycerides are converted into fatty acids and glycerol upon aging. the analytical importance is the value is the measure of the amount of fatty acids which have been liberated by hydrolysis from the glycerides due to the action of moisture, temperature and or lypolytic enzyme lipase. defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 162 © adama science & technology university https://ejssd.astu.edu.et 2.5.4. cu and fe determination vegetable oils are widely used in the cooking and food processing, cosmetics, pharmaceutical and chemical industries10. plants and animals depend on some metals as micronutrients. metal elements such as na, k, ca, mg, fe, cu, zn and mn, are essential nutrients for human growth. however, certain forms of some metals can also be toxic, even in relatively small amounts, and therefore pose a risk to the health of animals and people. metal elements such as cd, pb, cd, co, and cu, could also have detrimental effects on health. this condition is considered for the determination of iron occurring normally in commercial oils and fats, i.e. as scaps or in their organically combined forms in solution in the oil. acid extraction suffices for these cases and has been found preferable to the ashing technique. where, however, the presence of iron form extraneous sources in less soluble inorganic forms, e.g. ferrosilicate, is suspected, total iron should be determined by ashing and alkali fusion. the pink colour formed by reaction of fe+++ with thioglycollic acid. 2.5.5. soap content the ester is heated with aqueous alkali (sodium hydroxide) to form an alcohol and the sodium salt of the acid corresponding to the ester. the sodium salt formed is called soap. soap (a weak base) is reacted with acid to form free fatty acid. this method assumes all the weak base is in the form of sodium oleate. 2.5.6. peroxides oxidative rancidity is caused by the attack of oxygen on the unsaturation centers in oils and fats with the formation of peroxides. rancidity is a process which is accompanied by formation of unpleasant odour, defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 163 © adama science & technology university https://ejssd.astu.edu.et taste, as the result of action of moisture, air (o2) and enzymes. peroxide value is a measure of peroxides which indicate incipient rancidity. the method for determination of peroxide concentration is based on the reduction of the hydroperoxide group with hi (or ki) to liberate free iodine, which may be titrated. the peroxide value is expressed in terms of a milliequivalent of iodine formed per kilogram of fat. peroxide value (pv) is an important characteristic of the edible oils quality and appears as an indicator of the lipid oxidation and oil properties deterioration1. pv is related to hydroperoxides in terms of milliequivalents per kg of oil, which oxidize potassium iodide under the standard conditions of the test 2, 3. the peroxide number gives information about the number of peroxide compounds in the oil and hence of the age and quality of the edible oil. the lower the peroxide numbers the better and/or newer the oil3. 3. methodology preparation of test sample: liquid niger and linseed oils were used. the niger and lin seed oils used for the study were bought from adama and bishoftu market, available for customers to purchase for the purpose of consumption. the clear sediment free liquid sample was used directly after inverting container several times. determination of moisture: the moisture content of oils was determined using es/ iso 662. the loss in g of the niger and linseed oils on drying were mn= 0.0045 g, ml = 0.0075 g respectively. the mass in g of the materials taken for test was 5 g. determination of relative density: the ratio of the weight of certain volume of oil to the weight defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 164 © adama science & technology university https://ejssd.astu.edu.et of the same volume of water was taken. the volume taken was 10 ml for both niger oil and linseed oil tests. the es 56 was used for the determination. determination of refractive index: the es iso 6320; suitable abbe refractometer was used for the determination. saponification value determination: the cec 20:2013/es iso 3657 was used. a 2 g of niger seed and linseed oil was refluxed with 50 ml of 0.02m ethanolic koh separately, then the excess unreacted 0.02m koh was titrated against 0.5m hcl, using ph.ph indicator. determination of insoluble impurities content: the determination was made by application es iso 663. the soluble niger and linseed oil after saponification was used for the determination. a 0.02, normality of 50 ml standard potassium hydroxide solution was used. a) the iso 8294 graphite furnace atomic absorption method for the determination of copper and iron was used. the test portion of the oil in a graphite furnace connected to an atomic absorption spectrometer was vaporized for determination. b) determination of soap content: the es 65 was used for the determination soap content in niger and linseed oils. this method assumed all the weak base is in the form of sodium oleate. a simple titration with hcl was used to measure the amount of soap. a few drops of bromophenol blue indicator were added and the titration continued to the color change for that indicator. c) acid value: defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 165 © adama science & technology university https://ejssd.astu.edu.et the niger seed oil and linseed oil was dissolved and examined in ethanol/ether 1:1. the solution was titrated against 0.1m koh, in ph.ph indicator. the es/iso 660 was used for the determination of the acid value. 20 g of each sample was taken for the expected acidity less than 1. the 0.1, normality of potassium hydroxide solution was used for the titration. d) peroxide value: iso 3960 for determination of peroxide value-iodometric (visual) endpoint determination was used. the method for determination of peroxide concentration was based on the reduction of the hydroperoxide group with hi (or ki) to liberate free iodine, which was titrated. 4. results and discussions the physical and chemical properties of the oil were determined based on the methods described by the association of official analytical chemists2. tables 1 & 2 show the physico-chemical properties of the niger seed and linseed oils respectively. the peroxide number gives information about the number of peroxide compounds in the oil and hence of the age and quality of the edible oil. the lower the peroxide numbers the better and/or newer the oil. the peroxide value which is used as an indicator of deterioration of oils was found to be 3.59 and 3.19 meq/kg for niger and linseed oil respectively, indicating that the oils are fresh. this is because fresh oils usually have peroxide values below 10 meq/kg3. the soap content value in (%( m/m)) was found to be 0.001 for nigerseed oil which is in range of edible oil and not detected for linseed oil. copper and iron are not detected in both cases. the relative density at 20 was found to be 0.9220 which is below the defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 166 © adama science & technology university https://ejssd.astu.edu.et minimum level (0.9250) for niger seed and 0.929 for linseed oil which is acceptable range. the moisture and volatile matter value at 105 in (% (m/m)) was found to be 0.09 for niger seed oil and 0.15 for linseed oil which are acceptable in both cases. the insoluble impurities value in (%( m/m)) was found to be 0.01 for niger and 0.02 for linseed which is acceptable in both cases of which the maximum value is 0.05 above which no result cannot be accepted. the acid value corresponds to the amount of carboxylic acid groups in fatty acids and is given in mg koh per g sample. the older an oil is the higher the acid value as triglycerides are converted into fatty acids and glycerol upon aging. the free fatty acid was found to be 0.225 mgkoh/g (niger) and 0.295mgkoh/g (linseed oil) which is low, signifying that the oils are edible and can stay for a long time without getting rancid. the acid value was obtained to be 0.45 mgkoh/g for niger seed oil and 0.59 mgkoh/g for linseed oil. the saponification value is expressed as the amount of potassium hydroxide in milligrams required to saponify 1 g of fat under the conditions specified. it contains the information of the average molecular weight of all fatty acids present. it is reported that oils with low free fatty acid usually have high saponification value which is in accordance with the result obtained for the saponification value (192 mg koh/g) for niger seed oil and 189.17mgkoh/g for linseed oil6. the refractive index was obtained to be 1.4757at 40 for niger seed oil which is above the maximum level and 1.481 at 40 for linseed oil which is inacceptable range. defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 167 © adama science & technology university https://ejssd.astu.edu.et table 1: the physical properties of niger seed oil determined ser.no characteristic tested specification /test method standard requirements (min-nom-max) test result comment 1 peroxide value (milliequivalen t peroxide oxygen/kg oil) cec 20:2013/es iso 3960 10 3.59 passed 2 soap content (%(m/m)) cec 20:2013/es 65 0.005 0.001 passed 3 copper (cu) (mg/kg) cec 20:2013/es 3377:2007 0.1 not detecte d passed 4 iron (fe)(mg/kg) cec 20:2013/es 3377:2007 1.5 not detecte d passed 5 relative density at 200c (-) cec 20:2013/es 56 0.925 0 0.9270 0.9220 failed 6 moisture and volatile matter at 1050c (% (m/m)) cec 20:2013/es iso 662 0.2 0.09 passed 7 insoluble impurities (%(m/m)) cec 20:2013/es iso 663 0.05 0.01 passed 8 acid value and acidity (mgkoh/g oil) cec 20:2013/es iso 660 0.6 0.45 passed 9 refractive index at 400c (-) cec 20:2013/es iso 6320 1.466 5 1.4695 1.4757 failed 10 saponification value (mgkoh/g oil) cec 20:2013/es iso 3657 188 192 192 passed table 2: the physical properties of linseed oil determined ser.no. characteristic tested specification /test method standard requirements (min-nommax) test result comment defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 168 © adama science & technology university https://ejssd.astu.edu.et 1 peroxide value (milliequivalent peroxide oxygen/kg oil) /ces 18:2013 10 3.19 passed 2 soap content (%(m/m)) /ces 18:2013 0.005 not detected passed 3 copper (cu) (mg/kg) /ces 18:2013 0.1 not detected passed 4 iron (fe)(mg/kg) /es 66 1.0 not detected passed 5 relative density at 200c (-) ces 18:2013 0.912 0.933 0.929 passed 6 moisture and volatile matter at 1050c (% (m/m)) ces 18:2013 0.2 0.15 passed 7 insoluble impurities (%(m/m)) ces 18:2013 0.05 0.02 passed 8 acid value and acidity (mgkoh/g oil) /ces 18:2013 0.6 0.59 passed 9 refractive index at 400c (-) /es iso 6320 1.472 1.482 1.481 passed 10 saponification value (mgkoh/g oil) /es iso 3657 188 195 189.17 passed 5. conclusions and recommendation in conclusion, the lower the peroxide numbers the better and/or newer the oil and indicating that the oils are fresh. the acid value is also low, signifying that the oils are edible and can stay for a long time without getting rancid. these oils are with low free fatty acid usually having high saponification value which is in accordance with the result obtained for the saponification value for niger seed oil and for linseed oil. the low moisture content of the oil is advantageous in terms of storage stability since the lower the defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 169 © adama science & technology university https://ejssd.astu.edu.et moisture content, the better the storability and suitability to be preserved for a longer period. also, the results obtained for the saponification values signify that the oils are good for soap production. thus, the oils have great prediction in terms of their edibility, storability and also suitability for soap production. depending on the analysis results, we recommend that the niger and linseed oils local producers should be encouraged in terms of technology that is the way they are using to produce the product should improve, they should come together for better production and they should have enough place of work to sufficiently produce since their products are better for production. acknowledgments adama science and technological university (astu) for the financial support through a grant are gratefully acknowledged. i am thankful to ethiopian conformity assessment enterprise, for they allow us to their lab. references 1. getinet a, sharma sm. niger guizotia abyssinica (l. f.) cass. (1996) promoting the conservation and use of underutilized and neglected crops. 5. rome, italy: institute of plant genetics and crop plant research, gaterslebe/international plant genetic resources institute; pp. 1-59 2. aoac (2004). official methods of analysis of aoac (15th edition); association of official analytical chemists. washington dc, usa, p. 858 3. ewing g. w. (1971). tropics in chemical instrumentation. easton, chemical education publishers 4. seegeler cjp (1983). oil plants in ethiopia: their taxonomy and agricultural significance, wageningen: centre for agricultural publishing and documentation. defaru negera ethiop. j. sci. sustain. dev., 5 (1), 2018 170 © adama science & technology university https://ejssd.astu.edu.et 5. division of agronomy indian agricultural research institute new delhi – 110 012 6. luhs w., & friedt, w. (1994). non-food uses of vegetable oils and fatty acids. in d. j. murphy (ed.), designer oil crops (pp. 73-130). vch, weinheim 7. thompson, lilian u and cunnane, stephen c. eds (2003). flaxseed in human nutrition. 2nd ed. aocs press. pp. 8–11. 8. d. berab, d. lahirib & a. naga (june 2006). "studies on a natural antioxidant for stabilization of edible oil and comparison with synthetic antioxidants". journal of food engineering. 74 (4): 542–545. 9. adugna wakjira (2000). assessment of tissue culture derived regenerants of linseed (linum usitatissimum l.) in ethiopia. m. sc. thesis, department of plant breeding, faculty of agric. univ. of the free state, bloemfontein, south africa. 10. alfred thomas (2002). "fats and fatty oils". ullmann's encyclopedia of industrial chemistry. weinheim: wiley-v 46 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu research paper column chromatographic fractionation and evaluation of in vitro antioxidant activity of flavonoid enriched extracts of some selected citrus fruit peels olyad erba urgessa1,*, dereje atomsa oncho1, meseret chimdessa ejigu1, teshome gonfa hordofa2 1school of biological sciences and biotechnology, college of natural and computational sciences, haramaya university, ethiopia., p. o. box 138, dire dawa 2department of chemistry, college of natural and computational sciences, haramaya university, ethiopia, p. o. box 138, dire dawa *corresponding author, e-mail: olyaderba@gmail.com abstract it is a long and tedious process to isolate pure and pharmacologically active constituents from plants. this study aimed to enrich flavonoids of crude extracts from some selected citrus fruit peels and evaluate in vitro antioxidant activity of the flavonoid enriched extracts. enrichment was carried out by partitioning crude extract using silica gel column chromatography, testing presence of flavonoid in each fractions and pooling together positive fractions. flavonoid contents were determined by colorimetric aluminum chloride. in vitro antioxidant properties were investigated by dpph and nitric oxide radical scavenging, and reducing power activity assay. lemon peel’s flavonoid enriched extract showed significantly the highest flavonoid contents (9.57 ± 0.38). orange peel’s flavonoid enriched extract showed significantly the lowest flavonoid content (3.7 ± 0.45). lemon peel’s flavonoid enriched extract showed higher dpph radical scavenging (75.60 ± 2.38%) at 100 µg/ml than vitamin c. orange peel’s flavonoid enriched extract showed the highest nitric oxide scavenging (88.32 ± 1.37%) at 1000 µg/ml and reducing power (0.45 ± 0.5%) at 800µg/ml as compared to other flavonoid enriched extracts. a strong correlation between flavonoid enriched extracts of citrus fruit peel and antioxidant activity was failed to demonstrate by regression analysis. in conclusion, antioxidant activity of flavonoid enriched extracts of citrus fruit peels was confirmed. keywords: column chromatography, flavonoid, orange, radical scavenging. 1. introduction the search for effective, nontoxic natural compounds with anti-oxidative activity has been intensified in recent year as synthetic antioxidants such as butylated hydroxytoluene and butylated hydroxyanisole have recently been reported to be dangerous for human health (lobo et al., 2010). it has been found that peels of fruit are the main sources of total phenols and flavonoid in citrus fruits (ghasemi et al., 2009; bind et al., 2015; lim and loh, 2016). the peel which represents almost one half of the fruit mass contains the highest concentrations of flavonoids in the citrus fruit (asjad et al., 2013). citrus peels are rich in numerous active compounds like phenolic acids that have antioxidant properties (manthey and grohmann, 2001; naczk and shahidi, 2006). peel residues from sweet and bitter oranges, lemons, and mandarins have proved to be an important source of phenolic acids, flavonoids, flavanones, and glycosylated flavanones (xi et al., 2014; el zawawy, 2015). polar flavonoid structures were reported in mandarin and orange peels. hesperidin is, for example, a polar bioflavonoids and is the major active constituent of tangerine peel (citrus reticulata) (fathiazad and afshar, 2004; aghel et al., 2008) and sweet orange peel (citrus sinensis) (fathiazad http://www.ejssd.astu.edu/ olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 47 and afshar, 2004; belboukhari et al., 2015). research done by yusof et al. (1990) showed that the flavonoids content was richer in citrus peels instead of seeds. flavonoids act on biological systems as antioxidants, antiviral, anti-inflammatory and anti-tumoral agents. they capture and neutralize the oxidative agents, and quench free radicals (segev et al., 2010). it is a long and tedious process to isolate pure and pharmacologically active constituents from plants. thus, it is necessary to have the good methods available which eliminate unnecessary separation procedures (kirankumar, 2015). phytochemical screening enables in recognition of known metabolites present in extracts at earlier stages of separation and is thus economically important to know type of secondary metabolites before comprehensive separation procedure (kumar and pradeep, 2011). this study was aimed to enrich flavonoids of extracts from orange, mandarin, lime and lemon peels collected from dire dawa district, ethiopia using a simple open column chromatography, and to evaluate antioxidant activity of flavonoid enriched extracts. 2. materials and methods 2.1. plant material preparation fruits of orange (citrus sinensis), mandarin (citrus reticulate), lime (citrus aurantifolium) and lemon (citrus lemon) were collected at the ripening stage from dire dawa district farmers. the fruits were carefully hand peeled. the peels were cut into small pieces and dried in a ventilated oven at 60°c for one day. after drying, the peel fragments were ground for a few minutes in blinder and were refluxed with petroleum ether at 60°c for 8 hours to remove oil and chlorophyll. then, the marc was air dried to evaporate petroleum ether (cai et al., 2010). 2.2. crude extraction and screening for flavonoids the powder was extracted using soxhlet extractor with 80% ethanol at 78 °c for 6 hours (cai et al., 2010). the extracts were concentrated over a rotary vacuum evaporator at 45°c until semi-solid extract were obtained. ferric chloride method described by ajayi et al. (2011) and lead acetate method described by sofowora (1993) were used to detect presence or absence of flavonoids in crude extracts. positive crude extracts were stored at –20°c for column fractionation. 2.3. flavonoid enrichment and quantification slurry of silica gel (100-200 mesh size) was made using hexane and the columns were packed to the level of two third. five gram of crude extracts were mixed with small amount of silica gel and loaded on the top of the column. flavonoids are weakly polar and in this study crude extraction was done using highly polar ethanol and the expected extracts were enriched with polar phytochemicals. in order to enrich the crude extracts with flavonoid, mixture of hexane and ethanol was used as eluent to effectively separate non-polar photochemical. therefore, elution was started with 70:30, and continued using 60:40, 50:50 hexane to ethanol, and finally 80:20 ethanol to distilled water. all the collected fractions were tested for flavonoid and the positive fractions were pooled together. the pooled fraction was concentrated at 45°c rotary evaporator until the formation of sediment. the sediment freeze dried and represented the solidstate product of flavonoids. freeze drying was conducted to make suitable mass measurement. total flavonoid content of the purified extracts was determined. colorimetric aluminum chloride method was used for flavonoid determination (ghasemi et al., 2009; asjad et al., 2013). briefly, 1 ml of mg/ml of freeze-dried extracts in ethanol were separately mixed with 0.1 ml of 10% aqueous aluminum chloride, 0.1 ml of 1 m potassium acetate, and 2.8 ml of distilled water, and left at room temperature for 30 minutes. the absorbance of the reaction mixture was measured at 415 nm with uv/visible spectrophotometer. distilled water was used as a blank. total flavonoid contents were calculated as quercetin equivalent from a calibration curve. regression linear line of y= 0.0005x+0.029, r2 = 0.999 of quercetin (200 -1200 µg/ml) was used as a reference standard curve (kamtekar et al., 2014). 2.4. evaluation of antioxidant activity 2.4.1. dpph∙ scavenging activity the stable 1, 1-diphenyl-2-picryl hydrazyl (dpph) radical scavenging activity carried out following methods described by ghasemi et al. (2009) and asjad et al. (2013). briefly, different concentrations of extracts and standards (100 g/ml, 200 g/ml, 400 g/ml, 800 olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 48 g/ml and 1000 g/ml) were prepared using ethanol. four ml of each concentration and 4 ml dpph (100μm in methanol) was added in 10 ml capacity test tubes. the solution were mixed and allowed to stay for 15 minutes at room temperature in dark place. the absorbance was recorded at 517nm. mixture of ethanol and methanol was used as a blank, dpph solution without extract used as a control and vitamin c as standard. the experiment was done in triplet. the percentage quenching of dpph∙ was calculated as follows: 100 a a -a dpph. of inhibition % br arbr          where, abr is the absorbance of dpph∙ solution alone (without sample or standard solution addition) and aar is the absorbance after reaction was taken place. in this dpph assay of the flavonoid enriched extracts, the samples and dpph were dissolved in different solvents. this is because the sensitivity of spectrophotometric measurements of dpph in methanolic solutions is better than that of dpph in ethanolic solutions (om and tej, 2008). therefore, dpph was dissolved in methanol. on the other hand, the soxhlet extraction was carried out using ethanol and column fractionation was using mixture of hexane and ethanol, and mixture of ethanol and water. as complete dissolution of extracts stabilizes uv reading, the flavonoid enriched extracts were dissolved in ethanol. 2.4.2. nitric oxide scavenging activity nitric oxidant scavenging activity was conducted following methods described by ebrahimzadeh et al. (2009) and mahmoudi et al. (2009). briefly, different concentrations of extract (100, 200, 400, 800 and 1000 μg/ml) were prepared dissolving in ethanol. sodium nitroprusside (1 ml, 10 mm), in phosphate-buffered saline, was mixed with each of these concentrations (2 ml) separately and incubated at room temperature for 180 min. the same reaction mixture, without extract was served as control. after the incubation period, 3 ml of griess reagent (1% sulfanilamide, 2% h3po4 and 0.1% n-(1naphthyl) ethylenediamine dihydrochloride) was added. the absorbance of the chromophore formed was read at 546 nm. vitamin c was used as standard. the percentage scavenging of no. was calculated as follows: 100 a a -a no. of inhibition % br arbr          where, abr is the absorbance of no∙ solution alone (without sample or standard solution addition) and aar is the absorbance after reaction was taken place. 2.4.3. reducing power determination different amounts of extract and standard (100, 200, 400, 800 and 1000 μg/ml) in ethanol were prepared. two ml of each concentrations were mixed separately with phosphate buffer (2 ml, 0.2 m, ph 6.6) and potassium ferricyanide [k3fe (cn)6] (2 ml, 1%) in to centrifuge tube (10 ml). the mixture was incubated at 35oc for 20 min. trichloroacetic acid (2 ml, 10%) was added to the mixture to stop the reaction, which was then centrifuged at 3000 rpm for 10 min. two ml of upper layer of the solution was mixed with 2 ml of deionized water and fecl3 (0.25 ml, 0.1%). the absorbance was measured at 700 nm. increased absorbance of the reaction mixture indicated increased reducing power. distilled water was used as a blank and vitamin c as positive control (ebrahimzadeh and bahramian, 2009). 2.5. statistical analysis experimental results were expressed as means ± sd. all measurements were replicated three times. the data were analyzed by an analysis of variance (p < 0.05) and the means were separated by duncan's multiple range tests. 3. results 3.1. extraction and screening for total flavonoids ferric chloride and lead acetate tests for crude extracts were confirmed the presence of flavonoids in all extracts and some fractions of column chromatography 3.2. flavonoid enrichment and quantification the result of silica gel column chromatography separations was summarized in table 1 and figure 1(a), figure 1(b), figure 1(c) and figure 1(d). the number of column fractions of orange crude extracts was found 8 and three of them were positive for ferric chloride test. most fractions eluted by 80:20 ethanol to water were found positive for all crude extracts of citrus fruit peels. all positive fractions were pooled together enriching flavonoid content of crude extracts. and the result of olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 49 determination of total content of flavonoid was summarized in table 2. lemon (citrus lemon) flavonoid enriched extract showed significantly the highest values of total flavonoid (9.57 ± 0.375 mg quercetin equivalent/g of extracts). table 1: column chromatography fractions of citrus fruit peels’ extract and flavonoid detection figure 1: column fractions and ferric chloride test of citrus fruit peels’ extracts selected citrus fruit solvent ratio no. of separated fractions elution order and fecl3 test orange 70:30 hexane to ethanol 1 negative 60:40 hexane to ethanol 1 negative 50:50 hexane to ethanol 2 negative 80:20 ethanol to water 4 the first three positive mandarin 70:30 hexane to ethanol 2 negative 60:40 hexane to ethanol 1 negative 50:50 hexane to ethanol 5 the fifth positive 80:20 ethanol to water 4 the first three positive lime 70:30 hexane to ethanol 2 negative 60:40 hexane to ethanol 1 positive 50:50 hexane to ethanol 2 negative 80:20 ethanol to water 6 the first four positive lemon 70:30 hexane to ethanol 1 negative 60:40 hexane to ethanol 2 the second positive 50:50 hexane to ethanol 4 all are positive 80:20 ethanol to water 6 the first four positive olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 50 table 2: total flavonoid contents for citrus fruit peel extracts the values are mean ± standard deviation (n=3). superscript letters compares means. means with similar letters show no significant difference, whereas means with different letters show significant difference at p<0.05. 3.3. evaluation of antioxidant activity the results of antioxidant activity evaluation were summarized in table 3, 4 and 5. lemon (citrus lemon) peel’s flavonoid enriched extracts showed significantly higher percentages of dpph radical quenching (p < 0.05) at100 µg/ml than ascorbic acid as a positive control. the flavonoid enriched extract of orange (citrus sinensis) showed the lowest percentage of dpph quenching at 100µg/ml. the flavonoid enriched extract of lime (citrus aurantifolia) showed the lowest (74.36 ± 3.08) while the orange flavonoid enriched extract showed the highest (88.32 ± 1.37) nitric oxide radical scavenging at 1000 µg/ml. the flavonoid enriched extract of orange showed significantly highest reducing power activity at 100 and 800 µg/ml compared to other extracts. reducing power of selected citrus fruit peel’s flavonoid enriched extracts found to be increased as concentration of the extracts increased. table 3: percentage of dpph scavenging by citrus fruit peel’s flavonoid enriched extracts table 4: percentage of nitric oxide scavenging citrus fruit peel’s flavonoid enriched extracts table 5: reducing power of citrus fruit peel’s flavonoid enriched extracts the values are mean ± standard deviation (n=3). small letters superscript compares between means in row, and means with similar small letters show no significant difference, whereas means with different small letters show significant difference at p<0.05. selected citrus fruit flavonoid enriched extracts (in mg of quercetin equivalent/g of the extracts) orange 3.70 ± 0.448a mandarin 5.24 ± 0.848b lime 5.54 ± 0.564b lemon 9.57 ± 0.375c concentration orange mandarin lime lemon vitamin c 100µg/ml 57.86±2.58a 68.45±0.54c 68.93±0.62c 75.60±2.38d 69.64±0.36c 200 µg/ml 66.79±0.36cd 68.93±4.21ed 69.52±0.54cd 71.55±1.35d 72.62±0.90d 400 µg/ml 69.40±1.09b 69.40±1.09ab 70.12±1.45ab 72.97±1.80ab 75.95±0.54b 800µg/ml 72.98±0.540c 73.21±1.56c 66.43±1.07ab 71.90±1.15c 78.21±2.34d 1000µg/ml 76.31±0.42d 74.88±1.76cd 62.62±0.21a 71.67±1.09b 79.40±1.03e concentration orange mandarin lime lemon vitamin c 100µg/ml 78.63±2.60ab 85.47±0.43c 83.76±1.28bc 86.61±0.89cd 91.68±7.41d 200 µg/ml 79.91±1.13a 85.19±1.08ab 82.91±2.67ab 87.32±1.08bc 91.80±1.54c 400 µg/ml 81.05±0.99ab 83.90±2.15b 77.49±6.34ab 86.04±0.65cd 91.92±4.58d 800µg/ml 85.76±0.65c 81.34±2.43b 76.64±2.46a 82.91±2.60bc 93.01±3.24d 1000µg/ml 88.32±1.37c 82.62±0.65b 74.36±3.08a 81.77±1.37b 93.43±4.71d concentration orange mandarin lime lemon vitamin c 100µg/ml 0.36±0.01c 0.21±0.02a 0.26±0.00b 0.26±0.00b 0.20±0.03a 200 µg/ml 0.36±0.03a 0.29±0.02a 0.27±0.00a 0.26±0.01a 0.76±0.01b 400 µg/ml 0.38±0.03ac 0.31±0.02ab 0.27±0.03ab 0.27±0.01a 0.77±0.06d 800 µg/ml 0.45±0.05b 0.34±0.01a 0.32±0.00a 0.32±0.03a 0.94±0.04c 1000 µg/ml 0.41±0.05b 0.43±0.03ab 0.41±0.05b 0.35±0.03ab 0.96±0.03c olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 51 3.4. correlation of flavonoid content and antioxidant activity linear association between flavonoid contents of selected citrus fruit peel’s flavonoid enriched extracts and antioxidant activity was analyzed using linear regression analysis and the results were presented in figure 2, 3 and 4. from the figure, linear association was weak (the correlation coefficient (r) value is near to 5). figure 2: correlation between flavonoid contents and dpph radical scavenging activity of flavonoid enriched extracts figure 3: correlation between flavonoid contents and nitric oxide scavenging activity of flavonoid enriched extracts figure 4: correlation between flavonoid contents and reducing power of flavonoid enriched extracts olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 52 4. discussion 4.1. enrichment, screening and quantification of total flavonoids it is necessary to have the good methods available which eliminate unnecessary separation procedures for phytopharmaceuticals from plant extracts. kumar and pradeep (2011) concluded that phytochemical screening is economically important as it enables recognition of known chemical constituents present in plant extracts at earlier stages of isolation and characterization. in this study, ferric chloride and lead acetate chemical screening methods were used to detect flavonoids in crude extracts of citrus fruit peels and column fractions. all crude extracts were tested positive and they were subjected to silica gel column chromatographic fractionation. the result of chemical screening showed that ferric chloride test confirmed the presence of flavonoids in some fractions of column chromatography (figure 1). some fractions that were confirmed the presence of flavonoids by ferric chloride test showed the absence of flavonoid by lead acetate test. in line with this result, andrew and kurt (2006) described that the lead acetate procedure is often unsatisfactory since some phenolics do not precipitate while ferric chloride is a general cover reagent for phenolic compounds and gives a blue-black coloration with flavonoids. isolation of pure and pharmacologically active constituents like flavonoids from plants is a long and tedious process. in this study, crude extracts of selected citrus fruit peels was fractionated using a simple open column chromatography, each fractions were tested for presence of flavonoids and positive fractions were pooled together to enrich flavonoid contents of extracts. kirankumar (2015) stated that it is necessary to have the good methods available which eliminate unnecessary separation procedures. andrew and kurt (2006) described that there is no single isolation strategy for the separation of flavonoids and conventional open-column chromatography is still widely used because of its simplicity and value as an initial separation step. in this study, column chromatography elution was started with 70:30, and continued using 60:40, 50:50 hexane to ethanol, and finally with 80:20 ethanol to distilled water. the results showed that the most fractions obtained by using 80:20 ethanol to distilled water were tested positive for flavonoid showing the highest extractive ability of flavonoid by aqueous ethanol. this is in line with the result reported by kirankumar (2015). bharathi (2016) found the presence of more flavonoid content in ethanol extracts than the hexane and ethyl acetate extracts. one fraction of mandarin and lime crude extract eluted by 50:50 and 60:40 hexane to ethanol, respectively, were confirmed the presence of flavonoid. in addition, one fraction of lemon crude extract eluted by 60:40 and three fractions eluted by 50:50 hexane to ethanol were found positive for flavonoid. this might be showed that peel’s crude extracts contain both less polar aglycones flavonoids and glycosides. andrew and kurt (2006) stated that less polar flavonoids (e.g., isoflavones, flavanones, methylated flavones, and flavonols are extracted with chloroform, dichloromethane, diethyl ether, or ethyl acetate, while flavonoid glycosides and more polar aglycones are extracted with alcohols or alcohol–water mixtures. colorimetric aluminum chloride method was used for total flavonoid determination. in increasing order, the total flavonoid contents were 3.70 ± 0.448, 5.24 ± 0.848, 5.54 ± 0.564 and 9.57 ± 0.375 for orange, mandarin, lime and lemon peels’ flavonoid enriched extracts, respectively (table 2). lemon peel’s flavonoid enriched extract showed significantly the highest values of total flavonoid while orange peel’s flavonoid enriched extract showed significantly the lowest values of total flavonoid. lower content of flavonoid in orange peel’s flavonoid enriched than lemon peel’s flavonoid enriched extract was reported by singh and immanuel (2014) and el zawawy (2015). 4.2. evaluation of antioxidant activity antioxidant activity should not be concluded based on a single antioxidant test model. antioxidant test models vary in different respects and are difficult to compare fully one method to other one (alam et al., 2012). in this study, antioxidant activity of the fruit peel’s flavonoid enriched extracts was assessed by three different methods: dpph radical quenching, nitric oxide radical scavenging and reducing power determination. dpph method is based on hydrogen atom transfer (hat) and electron transfer (et) antioxidant activities (bae et al., 2015). when a solution of dpph is mixed olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 53 with antioxidant (ah) that can donate a hydrogen atom, dpph is reduced and loses violet color (alam et al., 2012). dpph radical scavenging assay showed that lemon peel’s flavonoid enriched extract had significantly higher dpph radical scavenging (75.60 ± 2.38%) at concentration of 100 µg/ml than vitamin c as positive control (table 3). in line with this result, singh and immanuel, (2014) reported dpph scavenging of 75.9% for orange peel. in the present study, vitamin c showed significantly higher dpph radical scavenging activity than lemon fruit peel’s flavonoid enriched extracts only at 1000 µg/ml. orange and mandarin peel’s flavonoid enriched extracts showed quenching activity of dpph radical in a dose dependent manner. but, lime and lemon peel’s flavonoid enriched extracts did not show dpph radical quenching in a dose dependent manner. in line to this result, el zawawy (2015) reported dose dependent dpph radical quenching activity of orange peel extracts and found dose independent dpph radical quenching activity of lemon peel extracts. dpph radical quenching of tangerine (citrus tangerine) was found increase along concentration (won et al., 2014). nitric oxide (no·) scavenging assay is based on the sodium nitroprusside decomposition in aqueous solution at physiological ph (7.2) producing no·. under aerobic conditions, no· reacts with oxygen to produce stable products (nitrate and nitrite), the quantities of which can be determined using griess reagent (marcocci et al., 1994). the nitric oxide radical scavenging assay showed that lemon peel’s flavonoid enriched extract had similar scavenging activity (p > 0.05) with vitamin c at 100, 200 and 400 µg/ml (table 4). nitric oxide radical scavenging values for orange fruit peel’s flavonoid enriched were found increased as the concentration of extracts increases. munmar et al. (2015) reported nitric oxide scavenging value (79.42%) for orange varieties, which is similar with this study results at 100-800 µg/ml. reducing power assay is based on the reduction of fe3+ to fe2+ by an electron donation from reductants (antioxidants) in the samples. amount of fe2+ complex formed can be monitored by measuring perl's prussian blue at 700 nm. increasing absorbance at 700 nm indicates an increase in reductive ability (mahmoudi et al., 2009). reducing power assay results showed that mandarin peel’s flavonoid enriched extract had similar (0.21 ± 0.02) reducing power activity with vitamin c as positive control (0.20 ± 0.03) at 100 µg/ml (table 5). orange peel’s flavonoid enriched extract showed the highest reducing power at 800 µg/ml compared to other citrus fruit peel’s flavonoid enriched extracts. a higher reducing power than this study result was reported by mahmoudi et al. (2009) and cardeñosa et al. (2015). vitamin c showed significantly higher reducing power than evaluated citrus fruit peel’s flavonoid enriched at 200-1000 µg/ml (p < 0.05). reducing power of selected citrus fruit peel’s flavonoid enriched extracts found to be increased as concentration of the extracts increased. in agreement with this study result, al-anbari and hasan (2015) reported increased reducing power of some citrus leaves and seeds ethanolic extracts as concentration increases. 4.3. correlation of flavonoid content and antioxidant activity the correlation between total phenol contents and antioxidant activity of food, fruit and vegetables has been widely studied (klimczak et al., 2007; jayaprakasha et al., 2008; calado et al., 2015; ghasemi et al., 2015). as they reported, antioxidant activity of food samples, fruits and vegetables significantly increases with the presence of high concentration of total polyphenol content. in the present study, the correlation between total flavonoids contents and radical scavenging activity of citrus fruit peel’s flavonoid enriched extracts were analyzed. a strong correlation between citrus fruit peel’s flavonoid enriched extracts and antioxidant activity was failed to demonstrate by regression analysis (figure 2, 3, 4). the correlation coefficients were 0.65, 0.46 and 0.73 for dpph and nitric oxide radical scavenging and reducing power, respectively. this showed that the correlation between flavonoid contents of citrus fruit peel’s flavonoid enriched extracts and anti-oxidant activity is a weak. the correlations were insignificant for all assay methods (p > 0.05). supporting this result, lack of correlation between crude methanolic extracts of citrus fruit peel and dpph radical scavenging activity was reported by ghasemi et al. (2015). opposing this result, calado et al. (2015) reported good correlation between flavonoid content and antioxidant activity in olyad erba et al. ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 54 most food samples analyzed. about 42.2 %, 21.3 % and 52.9% variability of dpph and nitric oxide scavenging, and reducing power, respectively, was accounted for the difference in flavonoid contents (r2=0.422, 0.213, 0.529 respectively). it was known that the presence or absence of certain structure of flavonoid is important in antioxidant activity. hydroxyl group in the molecule, for example, can act as proton donating and show radical scavenging activity and reducing power (mensor et al., 2001; hou et al., 2003). 5. conclusion orange, mandarin, lime and lemon fruit peel’s fractions tested positive for flavonoid and pooled together showed antioxidants properties. the highest amount of total flavonoid content was found in flavonoid enriched extracts of lemon peel. maximum antioxidant activity was found in different citrus fruit peel’s flavonoid enriched extracts for different antioxidant assay methods. lemon showed highest dpph and nitric oxide scavenging and mandarin the highest reducing power. a strong correlation between citrus fruit peel’s flavonoid enriched extracts and antioxidant activity could not been demonstrated by regression analysis. it can be concluded from the study that the flavonoid enriched extracts had antioxidant properties that did not depend on the concentration of flavonoid and different antioxidant assay methods give different antioxidant activity results. it is recommended that lemon and peel’s flavonoid enriched extract can be used as a potential dpph scavengers and orange peel’s flavonoid enriched as nitric oxide inhibitors and reducing power. further isolation and purification of distinct flavonoid from the investigated citrus fruit peels will be required. acknowledgements this paper is part of haramaya university research grant coded hurg-2016-06-01-05. therefore, haramaya university, office of vice president for research affairs deserves gratitude for this research project grant. we also express our special thanks to dire dawa district, ethiopia, farmers for allowing us to collect samples of citrus fruit. reference aghel, n., ramezani, z., & beiranvand, s. 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(1990). naringin content in local citrus fruits. food chemistry, 37(2): 113-121. https://doi/ 133 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 students’ learning style preferences vis-à-vis their academic achievements in efl classes abiot mosisa1 and kassaye gutema2 1 dilla university school of social sciences: department of english & literature 2 adama sciences & technology university school of humanities & social sciences. p.o.box 1888 adama, ethiopia e-mail kassugut@gmail.com abstract this study aimed to identify the students’ perceptual learning style preferences and their academic achievements in efl. the study is a descriptive survey approach in which mixed method design was employed. the pertinent data were obtained from 245 students. all english teachers were also taken as the sample. in collecting data, a 4point likert scale questionnaire called perceptual learning style preference questionnaire (plspq) was used along with interview and document analysis. the information gathered through close-ended question of the plspq and document analyses were analyzed quantitatively with the help of spss for windows version 16. on the other hand, the data gathered through interview were analyzed qualitatively. descriptive statistics such as mean and standard deviation were used to describe the respondents’ preferences of perceptual learning styles. meanwhile, anova was used to see the significance of differences among the population means of the six plsps. moreover, paired-samples t-test of comparisons was the other statistics technique used to identify the mean of specific plsp, among the six, that was statistically significantly different from the others. it was found out that they were statistically significantly different from the others. furthermore, chisquare test was employed to observe the relationships between students’ plsps and their english language academic achievements. the findings of the study revealed that group, kinesthetic, tactile, visual, auditory and individual were students’ first, second, third, fourth , fifth and sixth preferred perceptual learning styles respectively. based on the findings, the means of the six plsps were statistically significantly different from each other. what is more, the study revealed that there weren’t statistically significant relationships between students’ plsps and their english language academic achievements. key words: learning styles, perceptual, academic achievement, preferences, 1. background of the study nowadays with the shift from teacher-centered to a learneroriented approach in language learning/teaching, understanding mailto:kassugut@gmail.com abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 134 © adama science & technology university https://ejssd.astu.edu.et the way students learn is of crucial importance. students take in and comprehend information in different manners. some like to see, and others like to hear. some prefer to learn individually or independently of others; while others enjoy interaction and relationship with their peers. it is widely believed that the different ways of how a learner takes in and processes information are collectively referred to as learning styles or learning preferences (reid, 1987). according to kolb, (2004) learning style is defined as individual differences in the way information is perceived, processed and communicated. learning style differs from individual to individual, between friends, brothers and sisters. thus, students with different learning styles understand and try to solve problems in different, relatively stable ways. learning styles consists of a distinctive behavior, which serves as indication of how a person learns and adapts to his environment. keefe (1997) states that learning style is composed of cognitive characteristics (the way an individual processes, stores, and retrieves information), affective (emotional and personal attributes like motivation sociality, risk taking and persistence) and physiological (which includes an individual’s preferred sensory modes-visual, auditory, kinesthetic etc.) there are factors that serve as relatively stable indicators of how a learner perceives, interacts with and responds to the learning environment. statement of the problem there are a plethora of research findings that show that realizing the students’ perceptual learning style and using a fitting teaching method is very essential for the academic achievement. however, students learning in abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 135 © adama science & technology university https://ejssd.astu.edu.et general and their perceptual learning style preferences in particular do not appear to be given due attention in most cases. it is argued that many teachers ignore the varying needs and learning styles of their students by claiming that they know what is best for their students. as such, they stick to the traditional ways of teaching, believing that those methodologies that have worked before would also work for today’s students. this appears to have become a serious problem and led to the declining of students’ level of english. some teachers seem to be reluctant to identify and use the ways their students prefer to learn the language, or even if they find out their students’ learning styles, they pay little attention. however, the actual reality is that teachers need to discover their students’ preferred ways of learning the language. they can teach in a way that is engaging to students and do what works best for them. felder (1996) stated that mismatches often occur between learning styles in students in a language class and the teaching style of the teacher with unfortunate effects on the quality of the students’ learning and on their attitudes towards the class and the subject. smith and renzulli (1984) stated that learning style inventory instruments have to be designed to help teachers modify their instructional procedures in the way students learn better in the classroom. nevertheless, at national level in general and at the school under consideration in particular, learning style inventory instruments were not designed to help teachers modify their instructional procedures in the way students learn better in the classroom and identifying and using students perceptual learning style was not experienced. abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 136 © adama science & technology university https://ejssd.astu.edu.et reid (1987) stated that students shift their major fields during their academic career that correspond with their learning style and prefer different content areas. these indicated that students’ learning preferences determine their choice of specific contents, subject matters, and the field of study. however, this scholar did not determine whether students’ lsp related to their academic achievement or not. furthermore, many researchers supported the idea that there are learning style preference differences among the students in language class. in this case, studying only the existence of learning style preferences (lsp) differences among individuals in an efl class was not enough. however, investigating the dominant, minor and neglected lsp of students’ in efl class and their achievement was very important, which the current study aimed to account for. objectives of the study the general objective of this study was to assess the students’ perceptual learning style preferences vis-á-vise their academic achievement in efl classroom. specific objectives the specific objectives of the study were to:  identify the dominant perceptual learning style preferences of students in efl classroom.  determine the minor perceptual learning style preferences of students in efl classroom.  identify the neglected perceptual learning style preferences of students in efl classroom  find out the relationship between students ‘perceptual learning style preferences and their academic achievement abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 137 © adama science & technology university https://ejssd.astu.edu.et research questions the following leading questions were used to determine the students’ dominant or major, minor and most neglected plsps and their academic achievement in an efl classroom.  what are the dominant perceptual learning style preferences of students in efl classroom?  what are the students’ minor perceptual learning style preferences of students in efl classroom?  are there neglected perceptual learning styles of students in efl classroom?  is there significant relationship between students’ perceptual learning style preferences and their academic achievement? 2. research methodology the study tried to describe the perceptual learning style preferences of students in an efl classroom. thus, descriptive survey design was used in the study to propound the perceptual learning style preferences of students. the data gathered using perceptual learning style preferences questionnaire (plspq) were analyzed using quantitative method design along with document analysis and a qualitative method to analyze the data gathered through interview. sampling technique comprehensive non-random sampling technique was used to sample the english language teachers in the school as they were just three in number. regarding students’ sampling, the total population of students was 679(342 male and 337 female). because it was not manageable to consider all of them as participant of the study, 245 students were taken from both sexes using stratified random sampling. the reason for opting for this sampling technique was to give equal abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 138 © adama science & technology university https://ejssd.astu.edu.et chance for students with in their section, sex and environment. data collection tools the instruments used for the collection of pertinent data are questionnaires, interview and document analysis. questionnaire perceptual learning style preference questionnaire (plspq) which was developed by reid was used by adapting and revising in the way that how students’ learned, studied, acted, reflected, or did in the english language classes to find out meaningful information for the study. reid (1987) developed the questionnaire for esl/efl students, and the present study was conducted in a country, ethiopia, in which english has been being learnt and spoken as a foreign language. therefore, this learning style inventory (questionnaire) was used to investigate students’ perceptual learning style preferences, which was appropriate for collecting vital information for the study. perceptual learning style preference questionnaires (plspq) was prepared by considering six learning style modalities such as auditory, visual, kinesthetic, tactile, individual, and group. these questionnaires had a total of 30 items with five items for each learning style category: auditory (1, 7, 9, 17, 20), visual (6, 10, 12, 24, 29), kinesthetic (2, 8, 15, 19, 26), tactile (11, 14, 16, 22, 25), individual (13, 18, 27, 28, 30) and group (3, 4, 5, 21, 23). document analysis one of the objectives of the research was to assess the relationship between students’ academic achievement and their learning style preferences. to determine the relationship between achievements and learning styles, students’ results were taken from abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 139 © adama science & technology university https://ejssd.astu.edu.et their first semester roster and arranged into five intervals based on ministry of education’s method of marking students’ card. the following intervals were the values assigned for the students’ achievement on the card: below 50%= poor, 50-59% =fair, 60-79% =satisfactory, 80-89% =very good, 90-100% =excellent. thus, the researchers used these intervals to see the relationship between students’ learning style preferences and their efl achievements. methods of data analysis descriptive statistics was used to see the mean and standard deviation differences among the students’ perceptual learning style preferences. therefore the collected data on perceptual learning styles were analyzed by using different statistical techniques with the help of the statistical package for the social sciences (spss) for windows, version 16.0. in this case, two descriptive statistics (mean and standard deviation) were used to see how much the five students’ plsps were different from each other and how far they varied from the average respectively. the data obtained through the questionnaire were further analyzed using anova, chi-square and paired samples t-test in order to define the significances of the data. hence, anova was used to see the existence of the significant differences among the population means of the learning styles because the variables were six, which were more than two: visual, auditory, tactile, kinesthetic, group, and individual. according to myers and well (2003, p.231), anova is a common statistical technique used for determining if there exists a difference among means of two or more groups. on the other hand, paired samples t test was used to see which mean differences will show abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 140 © adama science & technology university https://ejssd.astu.edu.et significant value in the students’ learning style preferences. paired samples t-test is a procedure or statistical test (technique) generally used in conjunction with anova to find which means are significantly different from each other. the third statistical test, chi-square, was used to see the relationship between learning style preferences and the students’ achievement in efl. 3. result and discussion students’ responses to the learning style preferences the data gathered from students through the plspq were computed by descriptive statistics (mean and standard deviation) to determine differences in students’ perceptual learning style preferences. the following tables show each item in the learning style questionnaire within each learning style modalities using both mean and standard deviation. the result from table 1 showed that the students differ in preference with the items of auditory learning style. as it could be seen, the participant students showed the strongest preference toward the item “number (7)” with a mean of 3.49 and standard deviation 0.766 where as they showed the least preference to the item “number 20” with a mean of 2.20 and standard deviation of 1.175. as it was shown, there were differences among students in their learning styles preference even within the modality of auditory. the means of students’ learning styles across the items took the following ranks: item no 7 first, then 9, 1 &17, 20 respectively. there were significant differences among the standard deviations of all items as shown in the table. this implied that students didn’t have similar attitude to these learning style. abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 141 © adama science & technology university https://ejssd.astu.edu.et table 1.the sum of responses, means, standard deviation deviation of each item from the auditory learning style domain. the result from table 2 indicated the extent to which the students agree with items of visual learning style. as it was indicated above, the students showed the strongest preference toward item “number 10” with a mean of 3.45 and standard deviation of 0.759 where as they show least preference to item “number 24” with a mean of 2.01 and standard deviation of 1.018. as it can be seen from table, there were differences among students in their learning styles preference even within the modality of visual learning style. there were not significant differences among the standard deviations of items no.24, and no 29; and item no.6 and 12 as shown in the above table. this indirectly implied that students did have similar attitude to these learning style’s items. on the other hand, the standard deviation of item no. 10 showed significant difference from the others. this showed that there were great differences among students toward item no. 4. the result from table 3 showed how much the students are s.no item no. sum mean s.d 1 i understand or learn the lesson easily when my teacher gives me instructions orally in the classroom 245 658 2.69 .968 7 i learn things more in the classroom when the teacher gives me instructions how to do something. 245 855 3.49 .766 9 i can easily remember what i listened rather than what i read. 245 741 3.02 .919 17 i learn the lesson more when the teacher gives a lecture orally in the class. 245 628 2.56 1.001 20 i learn the lesson more when i listen to someone in the class. 245 538 2.20 1.175 abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 142 © adama science & technology university https://ejssd.astu.edu.et differing in preferring items of tactile learning style. as it was indicated above, the participant students showed the strongest preference toward item “number 22” with a mean of 3.33 and standard deviation of 0.770. as it could be seen, there were differences among students in their learning styles preference even with in the similar learning style modality of tactile. there were not significant differences among the standard deviations of items no.11, and no 14 as well as 22 and 25 as shown in the above table. this implied that students did have almost similar attitude to the items of this learning style. table 2. the sum of responses, means, and standard deviation of each item from the visual domain no items no sum mean s.d 6 i learn and follow the lesson more when i read what my teacher writes on the blackboard. 245 757 3.09 .892 10 when i read instructions, i remember them better. 245 846 3.45 .759 12 i understand better when i read instructions. 245 812 3.31 .846 24 most of the time, i learn more when i read language contents in my textbook rather than listening to my teacher's presentation. 245 493 2.01 1.018 29 i know more about the lesson when i read different textbooks and guides rather than listening to my teacher's explanations in the class. 245 649 2.65 1.024 abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 143 © adama science & technology university https://ejssd.astu.edu.et table 3.the sum of responses, means, standard deviation of each item from the tactile domain s.no items no. sum mean s.d 11 i learn more by making a model of something practically that my teacher presents in the class. 245 755 3.08 .869 14 i learn more when i make something for a class project. 245 755 3.08 .865 16 i learn better when i make drawings as i study. 245 661 2.70 .991 22 i understand what i read, and heard more when i practically do them. 245 817 3.33 .770 25 i enjoy making something for a class project. 245 762 3.11 .784 table 4. the sum of responses, means, standard deviation of each item from the kinesthetic domain s.n item no. sum mean s.d 2 i prefer to learn by doing practically class activities that the teacher presents in the class. 245 871 3.56 .622 8 when i do things in class, i learn better. 245 725 2.96 .881 15 i learn more enjoyably when i follow my teacher teaching, explaining or doing something practically in the class. 245 866 3.53 .721 19 i easily understand what i learn in the class when i practically participate in a role play. 245 699 2.85 1.010 26 i learn best in class when i can participate in related activities. 245 659 2.69 .860 abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 144 © adama science & technology university https://ejssd.astu.edu.et table 5. the sum of responses, means, standard deviation of each item from the individual domain as it was indicated the participant students showed the strongest preference toward item “number 2” with a mean of 3.56 and standard deviation of 0.622 whereas, they showed the least preference to item “number 26” with a mean of 2.69 and standard deviation of 0.860. it could be understood that there were differences among students in their learning styles preference even within the modality of kinesthetic learning style. there were significant differences among the standard deviations of all items as shown in the above table. this implied that there were great differences among students towards each item. the above table makes it evident that the students differ in preference with the items of individual learning style. the participant students showed the strongest preference toward item “number13” with a mean of 2.83 and standard deviation of 1.044 where as they showed least preference to item “number 30” with a mean of 2.22 and standard deviation of 1.015. there were s.n item no. sum mean s.d 13 when i study alone, i remember things better. 245 694 2.83 1.044 18 when i work alone, i learn better. 245 590 2.41 .994 27 i easily and quickly finish anything when i do it alone. 245 602 2.46 1.053 28 i prefer doing any activity or project alone. 245 586 2.39 1.076 30 i prefer doing alone any activity that our teacher gives us. 245 543 2.22 1.015 abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 145 © adama science & technology university https://ejssd.astu.edu.et differences among students in their learning styles preference even within the modality of individual style. there were not significant differences among the standard deviations of all items as shown in the above table. this implied that students did have almost similar attitude to these learning style’s items. table 6.the sum of responses, means, std. deviation of each item from the group domain s.n item no. sum mean s.d 3 i often do classroom activities easily when i participate in groups. 245 750 3.06 .887 4 i understand what i learn more when i read or study together with my friends in free time. 245 841 3.43 .752 5 i do assignments, class works and other activities better when i do them with classmates. 245 771 3.15 .846 21 doing the class works and home works that our teacher gives us in pair or group makes me very happy. 245 823 3.36 .850 23 i often prefer studying with my friends rather than studying alone. 245 789 3.22 .845 the result from the above table indicates that the students choose group learning style. the students showed the strongest preference toward item “number 4” with a mean of 3.43 and standard deviation of 0.752 where as they showed the least preference to item “number 3” with a mean of 3.06 and standard deviation of 0.887. as it was shown, there were differences among students in their learning styles preference even within the modality of group learning style. there were not significant differences among the standard deviations of items no. 3, abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 146 © adama science & technology university https://ejssd.astu.edu.et no. 5, no.21 and no 23 as shown in the above table. this implied that students did have almost similar attitude to these learning style’s items. on the other hand, the standard deviation of item no. 4 showed significant difference from the others. document analysis data presentation and discussion this section was used to determine if there were significant relationship between students’ perceptual learning style preferences and their academic performances. thus, to do so, the students’ first semester results were arranged into five intervals based on ministry of education’s method of marking. therefore, to compute this relationship, chisquare was used as indicated below. the above table indicates the number of students in the given intervals of achievements that preferred each learning style. as it was indicated in the table, students’ achievements were arranged from poor to excellent. the largest number of students (57) among the target population was found in group learning style row whereas the least number of students (35) were observed in the row of individual learning style. to see the relationship between students’ preferences and their achievements, comparison was made between critical and observed values of chi-square. as it can be observed from the table, the 245 sample students were distributed in all of the five intervals of achievement categories. that is, 4 (1.6%), 14 (5.7%), 100 (40.8%), 87(35.5%) and 40 (16.3%) of the respondents were in the categories of excellent (90-100%), very good (80-89%), satisfactory (60-79%), fair (5059%) and poor (<50%) respectively. abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 147 © adama science & technology university https://ejssd.astu.edu.et as shown in the table, among the 4 (1.6%) of the students who achieved ‘excellent’ (90-100%), two were found in the kinesthetic and two in individual rows. moreover, of the 14 (5.7%) students who lied in the ‘very good’ (80-89%) category, 6(2.4%), 2(2.5%), 1(2.3%), 2(2.4%) 3(1.9%) of them are found in the group, kinesthetic, tactile, visual and auditory rows respectively. but for the rest categories, among the 57 (23.3%) of group learners, 6 (2.4%) and 18 (7.3%), 22 (9%) and 11(4.5%) of the students achieved satisfactory (60-79%), fair (50-59%) and poor (<50%) respectively. as it can be observed, group learners who were in the most dominant learning styles didn’t achieve excellent. on the other hand, among the 43 (17.6%) of the students who preferred the second major learning style, kinesthetic, 2(0.8%), 2(0.8%), 17(6.9%), 12(4.9%) and 10(4.1%) achieved excellent (90-100%), ‘very good’ (80-89%) satisfactory (60-79%), fair (50-59%) and poor (<50%), respectively. regarding the two learning style preferences that are found at the middle, tactile and visual, among the 40 (16.3%) of tactile learners, 1 (0.4%), 23 (9.4%) 11 (4.5%) and 5(2.0%) students lied in the intervals of very good (80-89%), satisfactory (60-79%), fair (50-59%) and poor (<50%) respectively. however, none of them scored excellent (90100%). among the 37 (15.1%) visual learners, 2 (0.8%), 15 (6.1%), 18 (7.3%) and 2(0.8%) students achieved scores in the intervals of very good (80-89%), satisfactory (60-79%), fair (5059%) and poor (<50%) respectively. but none of them scored excellent (90-100%). abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 148 © adama science & technology university https://ejssd.astu.edu.et table: 7. the relationship between students’ learning style preferences and academic achievement in chi-square test. types of learning style students’ first semester english score total <50% 50-59% 60-79% 80-89% 90-100% auditory count expected % of total 6 5.4 2.4% 15 11.7 6.1% 9 13.5 3.7% 3 1.9 1.2% 0 .5 .0% 33 33.0 13.5% visual count expected % of total 2 6.0 .8% 18 13.1 7.3% 15 15.1 6.1% 2 2.1 .8% 0 .6 .0% 37 37.0 15.1% tactile count expected % of total 5 6.5 2.0% 11 14.2 4.5% 23 16.3 9.4% 1 2.3 .4% 0 .7 .0% 40 40.0 16.3% kinesthet ic count expected % of total 10 7.0 4.1% 12 15.3 4.9% 17 17.6 6.9% 2 2.5 .8% 2 .7 .8% 43 43.0 17.6% individua l count expected % of total 6 5.7 2.4% 9 12.4 3.7% 18 14.3 7.3% 0 2.0 .0% 2 .6 .8% 35 35.0 14.3% group count count expected % of total 11 9.3 4.5% 22 20.2 9.0% 18 23.3 7.3% 6 3.3 2.4% 0 .9 .0% 57 57.0 23.3% total count expected % of total 40 40.0 16.3% 87 87.0 35.5% 100 100.0 40.8% 14 14.0 5.7% 4 4.0 1.6% 245 245.0 100.0% 4. conclusion the results showed that students had different attitudes towards the six plsps. that is, they did not prefer them equally. this shows that there were statistically significant differences in the means of students’ plsps. for instance, the results of the study computed on students’ plsps, group, kinesthetic, tactile, visual, auditory, and individual styles were found students’ first, second, third, fourth fifth and sixth preferred lss respectively. in other words, group and kinesthetic were students’ most preferred or abiot mosisa & kassaye gutema ethiop. j. sci. sustain. dev., 5 (1), 2018 149 © adama science & technology university https://ejssd.astu.edu.et most dominant plsps whereas, visual and tactile were their average preferred lsps. on the other hand, individual and auditory lsp were their least preferred plsp. this shows that, while applying group and kinesthetic learning styles in the classroom, most students’ participation can be seen but, while applying visual and tactile, moderate participation can be found in the classroom. however, while applying individual and auditory, almost all students’ reluctance of participation can be witnessed. moreover, based on the findings of the study, it can be concluded that language learning style preferences do not have a significant influence on students’ learning of the language and on their academic achievements. recommendation taking the findings of the study into consideration based on the basic research questions, the following recommendations are given:  teachers should take differences among the students into consideration when they design lessons.  students should also be advised to try to adjust themselves to different learning circumstances.  english language teachers should vary their teaching styles to accommodate the students’ learning styles.  a variety of teaching materials should be incorporated in the language classroom so that students are able to adjust to different learning situations so as to avoid any inconveniences when exposed to learning styles that do not suit them. references altan, z.m. &trombly, c. 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(1998). beyond training. cambridge: cambridge university press. 51 © adama science & technology university https://ejssd.astu.edu.et ethiopian journal of science and sustainable development (ejssd) p-issn 1998-0531 volume 5 (1), 2018 oromo indigenous knowledge: past experiences, current situation & future prospects for promoting sustainable sociopolitical development in ethiopia shelema regasa tufa adama science and technology university, astu, school of humanities and social sciences, philosophy program, adama, ethiopia. email: shelemaastu@gmail.com abstract this article seeks to vindicate the significance of utilizing overlooked indigenous knowledge of the oromo to promote socio-political development. this circumstance has consistently been resisted and actively contested by dominant partisan interests. as a consequence, today’s ethiopia is identified with the practice of conceiving and implementing social, economic and political policies of developed states which has proven to produce failed experiences and false starts. the main cause is that elites and policy experts alienate domestic cultures in its entirety assuming; they couldn’t make meaningful contributions to the way out of sophisticated socio-political predicaments. as per the concern of critical social philosophy, however, theories/policies are constructive when it is founded on, or theorized out of its own traditions, or conceived theories executed according to domestic realities and qualities. premised by this view, the article seeks to show the significance of exploring, restoring and reproducing thus integrating indigenous knowledge into socio-political program of the state. to this end, i seek to provide the decisive role that oromo indigenous knowledge may play in promoting sustainable social development and envisioning emancipatory politics. it is, therefore, far from, nor is intended to be, a descriptive account other than to define theoretical problematic in the context of ongoing intellectual and political program in the nation-state. keywords: indigenous knowledge, critical social theory, oromo people, sociopolitical development 1. introduction today’s ethiopia is usually positioned in academic and policy discourse, in the constellation of ‘developing’ nations of the third world. these entities are seen to be subject to progressive and profound alteration through their exposure to modernizing influences through the increasingly pervasive spread of western institutions, research mailto:shelemaastu@gmail.com shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 52 © adama science & technology university https://ejssd.astu.edu.et programs, techniques and interests (tower, 2000). paradoxically, whereas this is used to be an era in which cultural diversities has been recognized and even valorized, western institutions in the guise of disinterested, universal and inclusive have been identified as those which may lead to progressive homogenization. this “homogenization of not only system and techniques, but culture and identity is apparently appears to lead to the convergence of form and substance of thought, behavior and governance on the global level” (ibid). to the extent that this practice is divorcing than accommodating cultural differences, there exists no or little room for social theories and policies to have specific meaning in the cultural context of nonmodern others. for this reason, developing states need to evaluate the relevance of foreign policies/ theories vis-à-vis their own domestic realities. to this end, their first and most important task is to explore and restore their own domestic realities. it is only in doing so, and after this, can they be able to execute foreign theories and policies according to local standards. to the contrary, the heretofore state discourse is identified by suppressing domestic institutions, particularly, of the oromo for: (i)its potential threat to state discourse, as invoked antipolitical consciousness of society removed from power/knowledge monopoly of the state (1992: 534), (ii)unlike western tradition where the autonomy of the academy is guaranteed by its separation from the state and public discourse, academics in ethiopia are vulnerable to state control and ideologically orthodox. as a consequence, numerous works emphasized on oromo issues are produced recently by foreigners and oromo scholars in exile. even today, oromo scholars are shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 53 © adama science & technology university https://ejssd.astu.edu.et interested of being heard by the dominant global powers than by the ethiopian state although it claims the burden of policy formulation. based on perspectives drawn from critical social theory to sociopolitical study, the article seeks to signify the need to integrate indigenous knowledge of the oromo and others into states social-political programs. given this prospect is actively contested, the article is concerned and seek to signify the alterity of the misguided trend so far by broadening alternate views and prospects of utilizing domestic realities and indigenous knowledge. 2. history, tradition and indigenous institutions of oromo society the hitherto oromo studies have been challenged by two fundamental issues. the first one, which is identified with most african tradition, is the fluidity of oral discourse that discouraged documentation and proper study of traditional oromo indigenous knowledge. the second is the myth fabricated on the oromo history, culture and identity by abyssinian and their intellectuals to justify their own ideological and political program. the origin of this myth, according to megersa, (1994), can be traced to the work of bahrey (abyssinian monk) who wrote as history of galla (abyssinians derogatory name for the oromo) in 1593 that portrays oromo people as strangers, destructive, uncivilized and barbarian. having thus established itself in written discourses, the myth came to be taken as a factual representation of the oromo and was perpetuated and given credence and scientific validity by subsequent historiographers and anthropologists who then are established academic traditions without questioning the validity of shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 54 © adama science & technology university https://ejssd.astu.edu.et the data presented (ibid). consequently, after bahrey, the source of information for ethiopianist scholarship on the oromo became the public record in which depictions of oromo life seldom escaped being strongly colored by the view from the political center (gabisa, 2001). what is interestingly notable however is that; none of the myth’s accounts have been based upon or presented the oromo history from the perspective of the oromo people themselves (megersa, 1994). indeed, oromo society’s self-description and knowledge is radically opposite to the myths account. but, those accounts have been the main reason for scholars from within and out divided among themselves to engage in oromo studies. scholars such as mesfin w/mariam (1972), aleqa taye, etc. from within, and ullendorff (1965), lipsky’s (1962), braukämper (2002), marcus (1991) from abroad, are some of those who uncritically perpetuated constructed false image on the oromo. to the contrary, heberald (1963), baxter (1954, 1996, 1978),legesse (1973), levine (2012) among others are challenging and refuting the validity of the myth. for instance, john sorenson imagining ethiopia: struggle for history and identity (1993) is challenging the authority and authenticity of the myth unfolding the real identity, history and culture of the oromo. consequently, it is this deliberate misrepresentation on the one hand; and the fluidity of oral discourse on the other, why oromo people and their institutions have received very little attention within and outside of the state. what needs to be the topic of analysis is the reality; both from the oromo perspective as well as through other literatures. baxter et al. (1996.) for instance noted that, “there are great gaps in our shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 55 © adama science & technology university https://ejssd.astu.edu.et knowledge of oromo history and culture and social constitutions but it is clear, though different oromo groups vary considerably in their modes of subsistence and in their local social organizations, that they share similar culture and modes of thought”. bates (1979) puts: “the oromo were an ancient race, the indigenous stock, up on which most other peoples in the eastern part of africa have been grafted” (quoted in hussien 2006). it is also common knowledge that “all oromo groups share common cultural and historical roots in the form of kinship, political philosophy, worldview, and ritual” (jalata, 2001). gilchrist’s (2003) viewed the oromo as a strong group of people having distinct social, political, religious, linguistic, and cultural history from the semitic abyssinians they have now formed a nation with. furthermore, studies such as hassen (1990), legesse (1973), hussien (2006), megerssa (1994) from within, and all recent critical and extensive ethnographic studies uncover the fact that oromo people are the largest indigenous ethnonation in the horn of africa. in today’s ethnic based federal state structure (formed following the fall of dergue regime in 1991), the oromo people live in the regional state of oromiyaa the largest and the most populous of the nine regional states which controversially constitutes 40% of the total population and contribute 60% of total the state gdp. the oromo speak afaan oromo (the language of oromo), an afro-asiatic language and the most widely spoken language of the eastern cushitic linguistic sub-phylum (hussien, 2006: 257).for the fact that majority of oromo people still speak afaan oromo, they had and stillhave maintained traditional indigenous institutions and knowledge systems. shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 56 © adama science & technology university https://ejssd.astu.edu.et nonetheless, one thing that makes oromo people one of the most indigenous people in africa, according to (hussien, 2006, leggesse, 2000, 1973, jalata, 2011) is their possession of gadaa system the egalitarian cultural, political, economic and military organization that the people maintained but partially lost as a results of fall under the conquest of menelik ii at the turn of 20th century. gadaa system “represents a repository, a storehouse of concepts, values, beliefs and practices that are accessible to all oromo” (jalata, 2001: 59). according to legesse (1973), the oromo gadaa system is the most sophisticated socio-cultural and political organization ever known in the cultural traditions of african people.for legesse (1973, 2000), hussien (2006), and others, gadaa system was a complex institutional organization that embraced the totality of oromo peoples’ political, social, economic and religious life. gemachu (1994), who produced the finest and most comprehensive ethnographic study on the oromo, however is critical of his predecessors who emphasize and explain oromo world-view solely on the basis of gadaa system. for him, gadaa system is “a sub-system in a much larger philosophical thought system of the oromo”. according to him, oromo world-view could meaningfully be defined by three interconnected conceptsquoted below: it is three concepts (uumaa, ayyaana and safuu) which together constitute the basis of the oromo world-view. they are and should be seen as interlinked and interconnected aspects of a whole. together they constitute three different but related points of view about the rational universe as seen through oromo eyes. ayyaana is by which and shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 57 © adama science & technology university https://ejssd.astu.edu.et through which waaqa(oromo supreme god) creates the world, whilst uumaa refers to the entire physical world, both individually and collectively. in the oromo world-view, safuu(a moral category which constitutes the ethical basis upon which all human action should be founded) provides the moral and ethical code according to which events, whether at personal, social or cosmic level take place. (my italics, p, 221-226) knowledge is acquired, according to gemechu, by living in harmony with these laws such that a wise man is not a person who merely knows but a man who lives his knowledge. another important issue that gemachu insists is integral to the oromo system of knowledge is the definition, role and relation of man to one another and to other uumaa’sin the cosmos: in the oromo view, man is both logical abstraction in the sense of ayyaana and a concretely existing being in the sense of uumaa. in the cosmos, man constitutes one of the many elements. but, as a group of beings in the diversity of the cosmos, man occupies a very important place, for unlike all other natural beings, man alone is endowed with the intelligence to comprehend his ayyaana and uumaa through which he is able to understand cosmic events (p, 228). the oromo commencement of man is analogous to heidegger’s notion of dasien provided in his book “being and time”. this conception of man, according to gemachu (1994), workineh (2005), de salvaic, (1901) and others, above all enables the oromo maintainedharmony and solidarity between natural environments better than other neighboring shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 58 © adama science & technology university https://ejssd.astu.edu.et people forming the current ethiopian state. bartels also reinforces gemachu’s argument unfolding the complexity, relatedness and diversity of issues underlying the oromo social structures: oromo people speak a mutually intelligible language of their own. kinship relations and marriage customs are much the same, and so their attitude to leadership on one hand and to freedom of the individual on the other, the position of nuclear family, their concept of man and society, and their modes of experiencing the divine—all things which still find expression in many rites, ceremonies and forms of social intercourse. (quoted in jalata, 2001) traditional oromo institutions have been built on kinship system through which the community has sustained equity, justice, equality and harmony since the time immemorial. it is said to be basic social structure that fundamentally defines common interests in resource utilization, establishing political and religious leadership, and forming and maintaining harmonious relationship within oromo society (megerssa, 1994). moreover, oromo society have maintained and used indigenous institutions such as moggaasa (name giving), siiqe (female institution), gudifachaa (adoption) etc. these institutions and systems of knowledge have played a crucial role and are still largely exercised among the oromo community despite being challenged by century old abyssinian imperial administrative institutions. 3. prospects of critical social theory to knowledge production the commencement of theory, gaukroger put: “is anything which is, or can be, articulated in the form of a statement or set of statements which purport to offer, or offering, an explanation of shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 59 © adama science & technology university https://ejssd.astu.edu.et something” (1978). in this view, “a theory in work does not only consist of concepts but of propositions or statements pertaining to its object of knowledge as well, since the conceptual systems are the logical or conceptual conditions of existence” (ibid). most significant in the sociological experience elias has also written: “social theory is the conceptualization of society as a self-regulating nexus of events, and as something which was not determined in its course and its functioning by governments (1984). looking back to durkheim, “sociologists affirm the presence of something like the social realm as a reality, which has its own structure and regularities and generates its own quasi-natural patterns of development” (ibid). this tradition identified social facts with social groups’ collective representations in whichall general ideas and concepts are collective representations of individual and society. the ideahere is that, when members of the same society shared moral or other general concepts, they all had mental states with the same representational content such that; ideas, thoughts and words of a social groupstand for or represent the objects and processes in their environment. the ability to analyze social issues from different levels, to see the intersection and their mutual influences therefore lies at the heart of socio-theoretical endeavors: social theory is core to establishing frameworks for understanding in social science, interpreting human action and how social processes are contested and negotiated, as well as the interplay between various levels at which social relations take place from the micro to macro and individual to societal. (may and powell, 2008) it is therefore plausible to argue that theorization is the task shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 60 © adama science & technology university https://ejssd.astu.edu.et of either reflecting upon, or assumptions about the nature of knowledge and ideas of human action and consciousness: which are used to examine assumptions, explore basis of social facts, its structural dynamics and the place of human agency within the social world. in such a way, the role of social analyst is to reveal what is actually happening and may be happening, and the relationship of the two within social domains. it seems then that each theory constituting values of a particular culture may not meaningfully describe other cultures: first, social theories vary according to the cultural and intellectual traditions under which they are conceived and from which they draw their inspiration. second, all theories are not simply neutral mediums for interpretation; since they contain a ‘persuasive’ power which seeks to render their accounts either superior over, or different from, those of others. third, social theory not only seeks to account for the dynamics of society, but also reflects upon how knowledge about the social world is possible, as well as the nature of ‘social reality’.” (may and powell, 2008) it is also plausible to argue that there is lack of insights into an explanation of how social theories are actually related in depth. because of this, when social theory prescribing values of a particular cultural tradition is strictly applied to study other culture (to which it is incompatible) rather manipulates and corrupts those facts than producing knowledge. this incompatibility coupled with methodological gap in social study caused the emergence of varieties of social theories which questioned the acceptance and credibility of the prevailing. shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 61 © adama science & technology university https://ejssd.astu.edu.et frankfurt school, for example, coined critical theory in order to challenge the credibility of quantitative, empiricist and positivist social theories. this school also offered new conceptions it claimed is more adequate in characterizing contemporary society which can be identified by the following features. (i) it emphasizes and justifies social criticism which involves a reflection, a standing back and responding to events and actions which have occurred in course of social formation (dant, 2003). (ii) as an antidote to noncritical quantitative social theory, critical perspective seek to advance conception of critical and normative theory committed to envision emancipatory perspective (kelner, 1990). (iii) unlike conventional social theories,which have consigned culture to a secondarystatus, culture forms a context of action and thought in criticalorientation.(iv) it intrinsically seeks to challenge institutionally and structurally established norms, and can link together to order expert knowledge. (v), more importantly, critical social theory envisions emancipatory politics by reformulating framework to analyze social and political life based on awareness of the many obstacles to change and difficulties, dangers, and dimensions of social transformation (alway, 1995: 129).unlike marxist theory that sets economic exploitation as the foundation of social revolution, critical theory considerably broadened the category of potential agents of change to develop a more inclusive, expansive and modest conception of radical politics (ibid). opponents however perceived drawbacks of critical perspective. martin (1996), for example, downplayed the role of theory criticism in social studies commenting: “the proliferation of critical theories during the past shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 62 © adama science & technology university https://ejssd.astu.edu.et two decades has led to ‘crisis’ and ‘chaos’ in social theories” (1996). he noted that, unlike scientific theories which are used as a means of testing conjectures and perceptions theories in literary criticism engender diversity than integrating the results of the study (ibid). other opponents also questioned whether critical approach (characterized by diversity of theory and accelerating methodological fragmentation) make valuable contributions to improving conditions of people especially in a situation where technologies and economic status are determining life situation of modern society. while the modest few are raising the fact that; critical theories have not yet succeed to produce comprehensive and disinterested theoretical approach such that each new theory presents its claim as the only sensible alternative to those preceded it which end up to infinite regress (kellner, 1990). nevertheless, dahms (2008) considers the rejection of critical approach as “the ideology of modern society” that tends to sustain the status quo of modern thinking: the ideology of modern society may be the most apparent in the rejection of the need to reflect on the nature of reality in general, and of concrete challenges in particular, when reflection impedes the ability of decision makers to pursue wellestablished strategies or approaches to problems that are a function, and tied into the constitutional logic, of modern society – as a set of social structures and practices (p. 9) beyond arguments made for or against critical theory however, (and, since social crisis are associated with structural establishments), critical examination of preexisting social institutions and organizations seems to be the shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 63 © adama science & technology university https://ejssd.astu.edu.et precondition for solving than regenerating social problems. furthermore, the rationale of rejecting noncritical quantitative theoretical modellies in critical theorists’ orientation to knowledge and action which can be exemplified by habermas’ saccount. in order to show the gap of noncritical theoretical model, habermas initially differentiates what he calls ‘knowledgeconstitutive interests’: “a link between scientific methodology and social action” consisting of technical, practical and emancipatory (scott, 2007). the technical, refers to those aspects which are concerned with manipulating the environment and ensuring successful action, gaining and expanding control over natural objects and events (dant, 2003). the practical interest refers to aspects which are concerned with attaining and extending understanding and consensus in inter-subjective relations so as to achieve community and mutuality, while the emancipatory interest at the abstract level involves liberating men from historically contingent constraints through a process of 'self-reflection' (scott, 2007). based on these three interests, habermas recognize three types of knowledge and theorization. the first one is “historical-hermeneutic knowledge” that works through the cycle of interpretation aiming to relate ordinary utterances and social products to social lifeworld. theorization in this sense depends upon a prior understanding of the object of knowledge. the second is “analyticempirical knowledge” which is embodied in natural science. the third one is “critical-dialectical knowledge” which according to habermas is proper to social sciences for it combines the former two by recognizing their limitations so as to reconcile them shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 64 © adama science & technology university https://ejssd.astu.edu.et in a higher synthesis (scott, 2007). he is critical of positivist, because they have treated a distorted (analytic-empirical knowledge) as the paradigm for all knowledge which accord to him is too restrictive for social science (ibid). what is notable about critical theorists in general and habermas’s account in particular is the idea that; all knowledge systems are aspects of deep structures of social evolution by which we constitute the world of experience. since these rules are not immediately given to consciousness, they can only be dis-covered reflexively through a process of reconstruction for social transformation. it is therefore evident that critical theorists’ distinction of knowledge forms is overlooked or unrecognized in noncritical social theory while it attempts to conduct social studies along methodological tenets of hard sciences. provided that this practice misses much of social spheres to be studied, critical approach seeks to fill this gab by examining empirical life situations and goes beyond to grasp historically invariant regularities of social action; and combines the understanding of the two by permitting the realization of both through mutually transcending critique (ibid: 7). 4. the relevance of critical theory to oromo study in light of orientations and aspirations presented in the above topic, the importance of critical social theory to oromo study lies: first, in deconstructing historical misrepresentation of oromo culture, history and identity. the assumption here is that “critical studies challenge a top-down paradigm to either historiography or cultural studies, in order to challenge the production of false knowledge about plural culture maintained in diversified societies of ethiopia” (asefa, 2001). as we have seen, the heretofore shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 65 © adama science & technology university https://ejssd.astu.edu.et abyssinian state discourses on the oromo have irresistibly been twisting the reality and truth of the oromo propagating and justifying their own fabrication for ideological and political projects. this perversion has been carried out by the concomitant of political and intellectual programs as ezkel (2002) well captured it: in the eyes of the ethiopianist political and academic elites, undertaking a study on the oromo was permissible only if it enriched ethiopian studies and contributed to the survival of ethiopia as a unitary state, therefore, the one that deviated from this political goal was dismissed as intellectually deficient, and scholars who dared to produce such a study were derided, besmirched, and ostracized.” (p. 3) this intellectual canon perpetually resisted critical studies, particularly of which emphasized on the oromo cultures such that: “only interpretations that contributed to the production of a unitary, monolithic, master narrative passed the test of ethiopianist scholarship” (ibid). seen in this angle, it is selfevident that successive regimes have used political power for the objective of “destroying the cultures and identities of ethnic groups in order to form a nation with their own images” (jalata, 2001). this objective, however oppressive, appears to be a failed mission such that ethnic-groups’ identity, culture and language remained intact upon which today’s federalism is crafted. in spite of this, social/ethnic groups as they forcefully put together also borrowed each other’s cultures, social practices and religious views. because, with the intensification of globalization and information technologies, cultural borrowing is apparent among world-wide population let alone among those who have common shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 66 © adama science & technology university https://ejssd.astu.edu.et lived experiences and are still living in one nation-state. seen in positive angle, these realities are promising whereas surmounting the reoccurrence of cultural subordination requires forming politics meaningfully uniting all. to this end, critical deconstruction of preexisting historical discourses, social and cultural institutions and structural establishments is the first order task. the second significance of critical trend lies in exploring, restoring and reproducing overlooked indigenous knowledge of the oromo. this perspective in fact is recommended for african studies in general for it challenges the status-quo of modern culture in the first place. critical theorists convinced that: “since the beginning of enlightenment, historically unspecific theory seems universal, as if the same models and theories pertain everywhere, historical and cultural differences are overlooked” (jackson, 2009). and, “attempts to use the same methods everywhere led to a critical reaction from those who felt that other methods were needed when studying human societies” (ibid: 5). tsenay (1991) also states that, “it is in the guise of disinterested, universalistic, transcendental, and speculative discourse through which the occident humanity and rationality standardized for the remaining others”. critical reaction to condescending attitude of modern thinking therefore is justified as it “was directed not at the ends of the enlightenment but at the chosen means of achieving them” (jackson, 2009). in light of the above remarks, it is understandable that it is likely for non-west cultures left unstudied as incompetent and insignificant when evaluated by western methodological standards. if so, the problem lies in culture exclusionist western model. shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 67 © adama science & technology university https://ejssd.astu.edu.et because, social scientific study is all about the search for truth based on what mudimbe (1998) called “the right to truth”; so that, “each culture should be allowed to grow and develop without interference from others so that the temptation to merge cultures or impose one on another should be resisted. multiple cultures should be left to develop in parallel, not competing with each other but cooperating (jackson, 2009). legesse also noted what should be the aspiration of african study: we study african cultures so that they may live and grow to become the enduring foundation of a distinctive african civilization. in that process of growth, every culture has something vital to offer. man ‟s wider cultural identities must be allowed to grow, not by the predatory expansion of one civilization, but by the complementary integration of many diverse cultures. no human community, however humble, should be forced to give up its cultural identity without making a critical contribution to the larger reality of which it becomes a part. that remains true whether the larger reality is national culture, pan-african culture, or universal culture.” (1973: ix) the main reason for justifying critical perspective to both african and oromo studies is that, in the same way african history, civilization and consciousness is distorted by european colonizers and their exclusive canon of literacy, so do the oromo culture in ethiopian. as leggesse noted: “ethiopianist scholarship was conducted from the orientalist than africanist perspective, which tended to dissociate north ethiopian civilization from its african roots and from those populations of ethiopia whose culture are entirely african in character” (ibid).as a matter of shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 68 © adama science & technology university https://ejssd.astu.edu.et fact, what has been emphasized and presented in ethiopia so far is the identity, culture and language of one ethnic-group (mainly, the amhara’s) as it would subsume other ethnic groups. the argument to be made here is that, the continuity of this modality is unlikely to be altered only by criticism. it requires designing research program for the restoration and rehabilitation of cultural integrity of the oromo society. levine (2007) studying oromo culture commented: “perhaps, the oromo can contribute not only constructively to the organization of discourse in northeast africa, but in unparalleled way to contemporary efforts to organize dialogue in the global community”. accordingly, the most effective approach to cast off the yoke of exclusionist theoretical model of both european and ethiopianist at the same time is, to adopt critical theory to african and oromo study. given ethiopia is multicultural, multilingual and multinational state, the finding of distinctive cultures will enable the state to have broader foundation to expose and avoid obstacles to social justice, knowledge production and sustainable development? 5. instigating principles of gadaa imperatives of “emancipatory politics” beyond ‘deconstructionreconstruction’ role provided so far, prospects of critical theory can also play broader role in the process of political reform .it appears to be essential as critique builds the possibility of resistance: to established views and opinions about governance; to the takenfor-granted authoritative political culture; to simple acceptance on the basis of convention or established authority (dant, 2003: 7).it offers not only thoroughgoing critique of sustained shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 69 © adama science & technology university https://ejssd.astu.edu.et political culture but also a model of thought to change it. in our context for instance critical orientations may offer instances of utilizing social norms and values as integral basis of ongoing democratization program. successive governments’ political projects actively contested this perspective, which according to baxter, was crafted along quasi-authoritarian regime in europe: “just as the expansion of the european empire in africa coincided with that of abyssinian, so the latter took on some of the same sanctimonious assumptions of bringing civilization to the savages (1994). bulcha (2011) add: “the source of ethiopian states’ exclusionary policy and practice has, in part, been an imperialist arrogance that regards non-amhara indigenous cultures as inferior and un-ethiopian”. keller (1995) noted its implication as: “nation-building in sudan, ethiopia and somalia has been unsuccessful, because none of these states possessed the needed cultural basis”. the two main factors affecting this task he identified are: “on the one hand, leaders proved to be incapable of developing new social myths which could serve as the ideological foundation for nationbuilding; and on the other, they attempted construction on principles alien to their culture” (ibid). the present regime also seen showing little or no concern to overcome the hitherto been constraints to both nation-building and democratization of the state: the present regime’s ethnicbased federal set-up, designed along a liberal democracy trajectory, appears to be failing to produce the desired result. what is being implemented as democratization and decentralization of power by the new regime to address the demands and claims of the shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 70 © adama science & technology university https://ejssd.astu.edu.et country’s diverse communities seems to be leading to a deadend. the central problem is the contradictory actions of the regime, its democratization and decentralization policy on paper and centralization in practice, which has failed to make a major departure from the country’s past authoritarian political trajectory (merera, 2007). he adds, “the ethnic-based model of federalism appeared to be a response to the much debated ‘national question’ since 1960s among the forces of change while multiparty democracy seems to be motivated to get support of the victorious west in the cold war” (unpublished article: ‘twenty years of experimenting with revolutionary democracy: election and democratization in ethiopia, 19912010) during the first decade of administration little political, cultural and religious freedoms are tolerated whereby majority accentuated it as the antithesis of erstwhile socio-cultural, religious and political oppression of century old amhara-led imperial regimes. in due course, it revealed that it remained centralist authoritarian in a manner reminiscent of previous regimes where theory and practice are totally different. like its predecessors, it is endorsing ill-conceived policies and political program of u.s which has mainly shaped by u.s government’s1global strategic interests and geopolitics rather than the mutual benefits of the people (asefa, 2011: 131). it merely intended to build relation with ruling class and their repressive and exploitative governments: since the end of the cold war in the early 1990s, the u.s. has been using africa for its shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 71 © adama science & technology university https://ejssd.astu.edu.et objective of the so-called war on global terrorism by allying with some dictatorial and terrorist african regimes, such as that of ethiopia, that engage in state terrorism and gross human rights violations while giving lip service to the issues of democracy, human rights, and economic and social development. (ibid) it is said to be a regime in state of political turmoil when offering democratic principles on paper and less inclined to put into practice. this, for instance, is shown by its negligence to address oromo’s demand for afaan oromoo to be the official language of state among others. tower (2000: 69) stated: “the entrenched use of amharic as official language and local color is the indicative of states strategic manipulation of domestic cultures which implicitly denies the conception of any proprietorial or intellectual rights for others in the present conduct or future development”. provided that the oromo are not linguistic minority and afaan oromo is the mother tongue of more than forty percent2 of the total population, this proscription is morally and politically unjustified. more specifically “given the oromo, more than any other group, suffered under ‘one language’ policy of amharization political program because of their language” (matsuda, 2005: 5), and at a time when countries such as canada and switzerland, among others, are functioning well with more than one language, this prohibition is illegitimate at best and a resort to injurious legacies of the past at worst. it is reasonable to assume that as long as past experiences are implicating current states of affairs shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 72 © adama science & technology university https://ejssd.astu.edu.et (and, since there has been no democratic culture whereby preexisting sociopolitical, cultural, economic institutions are still preoccupied by the mind-set of the past legacies) democratization, particularly of multinational /cultural democracy in ethiopia, by no means is claimed here and now. but, democratization which is only introduced by present regime should be perfected to promote sustainably progressive social, political and economic development. this imperative, according to keller (1995), legesse (1994), baxter (2002), baissa (1994) and others, who are well aware about realities in the nation-state, is far-fetched unless socio-political program is broadened to incorporate indigenous ethos and values as integral basis of nation-building as well as democratization. they all justify this perspective by presenting gadaa system as an example: which according to oromo historian and researchers is the classic example of traditional african form of democracy that “comprises legislative, executive and judiciary body of oromo political philosophy” (keller, 1995: 624). legesse, who conducted extensive critical research on borana oromo gadaa practices, presented the overview of gadaa system as: is a system of gadaa classes (luuba) or segments of generations that succeed each other every eight in assuming political, military, judicial, legislative and ritual responsibilities? a ‘generation’ is forty years long and there are five segments (gadaa classes) in it. each one of the active gadaa classes (luuba)––beyond the first three grades––has its own internal leaders (hayyuuaduula) and its own assembly (ya’ii). the leaders of the luuba become the leaders of the nation as a whole when they come to power as a shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 73 © adama science & technology university https://ejssd.astu.edu.et group in the middle of the life courses. the class in power (gadaa) is headed by an officer known as abbaa gadaa or abbaa bokuu in different parts of the oromo nation, terms that mean “father of the institution” or “bearer of the symbol of authority” respectively. (2000) accordingly, gadaa system is not independent of other sociocultural institution, but only functions in the interconnected manner. qaalu institution (electors’ and ritual leaders), oromo ethics called safuu and national assembly (gumii) are the building blocks of gadaasy stem without which it may not sustain justice, order and harmony among the community since the time immemorial. moreover, gadaa system has also maintained the principles of check and balance (by its three organs), balanced opposition (among five parties), and power sharing between higher and lowers administrative and balanced representation of all clans, lineages, regions, and confederacies (jalata, 2012). “gadaa as an integrative system organize male oromo according to hiriyaa (age-sets) and luuba (generation-sets) for social, political, and economic and military purposes” (jalata, 1991). most importantly, rule of law is the integral element of the system so that “abbaa gadaa/abbaa bokuu who violates the rule is recalled before the end of his tenure” (baissa, 1994). to the contrary of authoritarian structured culture of politics, gadaais identified by the following characteristic features. (i) the ethos of gadaaplaced great value on solidarity than domination which in turn necessitated the pursuit of unanimity, (ii) its philosophical foundation is cosmological (ecocentric) than purely anthropological as it gives priority for harmonious relationship between humankind and natural environment, (iii) it shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 74 © adama science & technology university https://ejssd.astu.edu.et essentially promote the principle of sharing than exploitation that of which is undermined in contemporary politics, (iv) “in contrast to western democracy that of which characterized by pushing aside young and elders thus deprived legitimate role in political life, age and generation based democracy of the oromo does a better job of distributing power across generations and age groups,” (legesse, 2000). in such a way, gadaa system ensure that rights are distributed among generations thereof no generation that is mature enough to be able to bear the rights and duties of citizenship is prevented from taking part in political life (ibid: 248). furthermore, gadaa is a political system grounded on indigenous ethos of the oromo whereby norms of society plays a key role in political leadership. its philosophical aspect is rooted in belief system of the people sustained across generations in that each class of society partakes to determine political, economic, religious, social and cultural affairs. by virtue of this, baissa (1994), legesse (1994, 2000), and harbert s. lewis (1994) overtly argue that gadaa transcends the realm of mere governance principles of modern democracy. regardless of this, the worth of social harmony, good governance, leadership and political power eventually diminished following the oromo fall under authoritarian rule such that the community apparently founding strange and unfamiliar political contexts. it is therefore evident that, the presentation of gadaa system alone indicates a huge gap in states academic, policy and political program as it alienate such a valuable institutions. it also reveals policy makers tacit acceptance of ‘cultural universalism’; that evokes forms without substance, universality without particularity and shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 75 © adama science & technology university https://ejssd.astu.edu.et objectivity without subjectivity. contrary to this assumption, policy perspectives of critical social theory “engages in a form of criticism of social formations that arises precisely through the awareness of the failure of political action to bring about the changes needed in political and social formations” (always, 1995). since the hitherto intellectual tradition actively resisted culture study in general, prospects of critical trend certainly is decisive for salvaging oromo indigenous institutions such as gadaa and system of knowledge that would facilitate the transmission of cultural experiences. this perspective is decisive for uprooting authoritarian political culture; and in the long run can serve as the basis for the institutionalization of democratic political system. (baissa, 1994). it seems then that, the tendency to implement foreign policies and political programs without at least engaging in dialogue with domestic realities is to assume that domestic traditions, at the very minimum, is unlikely to make any meaningful contribution to the quest for a solution to sociopolitical and economic problems (ramose, 2002).this practice can hardly be transformative without harnessing ‘is’ with ‘ought’: the reconciliation of facts and norms beyond established political and intellectual predicaments. it requires emancipatory politics: “politics informed by a vision of distinctness without domination, a politics of a plurality of agents, a multiplicity of actions, and a vastly expanded arena of political struggle” (alway, 1995).while, political reform in ethiopia no longer regarded as a mere regime change :without defining and implementing principles of good governance; and unless designing research program capable of reproducing social scientific knowledge to understand shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 76 © adama science & technology university https://ejssd.astu.edu.et historical and existential social relation in the state, within a region and the world. this is through which erstwhile cultural colonialism, political oppression and economic exploitation is avoided once and for all. 6. concluding remarks one thing apparently discouraging democratization and sustainable development of most developing states of africa and ethiopia in particular is associated with uncritical adaptation and implementation of foreign institutional paradigms. since this practice ignores even divorced indigenous cultures (all together) as a basis of analysis, emancipatory perspectives cannot be envisioned without at least reversing and correcting this modality. the prospect of transforming the hitherto been sociopolitical predicaments is precisely; reawaking the ignored, unfocused and overlooked sociocultural institutions to engage in dialogue with the conceived one. in presenting oromo experiences and situation in ethiopia, it is evident that consecutive regimes have been perverting facts about the people in its entirety without reservation. to end its continuity, prospects of emancipation should be drawn in line with political and academic programs; as both were, and still are, the means of perversion. most importantly, it is essential to integrate critical social theory, as it seeks to find out cultural and political norms to more heterogeneous societies like ethiopia. as a matter of fact, inadvertently and ill-conceived policies for a long period under different regimes brought millions to the brink of starvation, political detentions and turmoil and long civil conflict (bahru, 2001). the way out of these phenomenon necessitate the institution of political program informed by shelema regasa ethiop. j. sci. sustain. dev., 5 (1), 2018 77 © adama science & technology university https://ejssd.astu.edu.et indigenous knowledge capable of resisting the social epistemology of domination from its own tradition. just like orthodox social theory (a prototype of ethiopian scholarship) is failed in the occident tradition then necessitate and invite dissent voices of multiculturalism, it is also irreconcilable to let indigenous knowledge of the oromo and other ethnic groups to share a stake in state’s social, economic, intellectual and political program. irrespective of this, mere replication of foreign institution without reconciling with domestic realities (or, at least giving the local flavor) will be unauthentic, misguided and unsuccessful. foreign policies and practices, however declared its objectivity, should tolerate cultural particularities as ingredients of interpretation, through which policies (of any) could be conceived and executed according to local standards and qualities. references alway, j. 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(2000), “formal schooling, identity and resistance in ethiopia”, change: monograph, pp, (6681) verharen, ch. c. (2006), “sage philosophy, rationality and science: the case of ethiopia”, ethiopian journal of the social sciences and humanities, publication of addis ababa university, 4(1): 14-32 workineh, k. (2005), “the utility of ethical dialogue for marginalized voices in africa”. a discussion paper, department of philosophy, addis ababa university 78 © 2022 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 9 (2), 2022 journal home page: www.ejssd.astu.edu.et astu review paper challenges and solutions in biogas technology adoption in ethiopia: a review ashenafi abebe asfaw, natei ermias benti wolaita sodo university, department of physics, collage of natural and computational sciences, wolaita sodo, ethiopia article info abstract article history: received 18 may 2022 received in revised form 24 july 2022 accepted 29 july 2022 biogas is a gas that is produced when organic matter decomposes. biogas produced by anaerobic digestion may be a viable energy source for rural ethiopia. it is suitable for cooking as well as generating electricity. there are over 18,000 biogas digesters dispersed throughout ethiopia, and despite the benefits of addressing energy-related issues like environmental and energy scarcity, the country's use of biogas is not rising dramatically. this article provides an overview of biogas technology in ethiopia and discusses the obstacles and opportunities associated with its expansion. high initial investment costs for digesters, a lack of biogas substrates, a lack of biogas research, a failure of the biogas pilot phase, a lack of public awareness campaigns, insufficient construction and maintenance expertise, low biogas technology efficiency, minimal biogas application, and a lack of appropriate bio-slurry management were identified as barriers to biogas technology expansion in the country. it was stressed that biogas plants installed throughout the country, particularly in rural areas, should be sized appropriately for the substrate available. furthermore, the calorific value of biogas should be increased in order for it to be used to power generator sets and internal combustion engines. keywords: adoption anaerobic digestion biogas technology renewable energy ethiopia 1. introduction agriculture, industries, and service sectors all rely on energy to drive economic development. in the current global energy system, fossil fuels in the form of coal, oil, and natural gas are the primary sources of energy; approximately 80% of global energy still comes from fossil-fuel-based systems. some of the problems associated with these energy systems are (i) they cannot replenish themselves as quickly as they are exhausted, (ii) they are limited, and (iii) having an adverse effect on the environment. global energy consumption is increasing at a rate of 2.3% per year. the consumption of fossil fuels (coal, oil, and natural gas) has largely met the increased demand (figure 1) (ipcc 2014; mekonnen 2015; christensen et al., 2017). renewable energy's contribution to global energy production is steadily increasing. in 2017, it accounted for 18.1% of global e-mail: nateibenti@gmail.com https://doi.org/10.20372/ejssdastu:v9.i2.2022.484 energy production, with modern renewables accounting for 10.6% and traditional biomass accounting for the rest (figure 1) (irena, 2012; ren21, 2019). figure 1: the share of renewable energy in globe final energy consumption (2017) (ren21, 2019). http://www.ejssd.astu.edu/ https://doi.org/10.20372/ejssdastu:v9.i2.2022......... ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 79 climate change, on the other hand, is among the most serious problems the world faces today (prasad et al., 2019). part of the problem stems from the widespread usage of fossil fuels in various sectors. fossil fuels were first used at the beginning of industrialization and are now responsible for the amplified atmospheric concentration of heat-trapping greenhouse gases (ghgs) (prasad et al., 2019). according to the ipcc 5th assessment report (ipcc, 2014), non-renewable energy sources emitted 47% of the 10 gtco2eq increase in annual anthropogenic ghg emission that occurred in the last decade (2001–2010), followed by industry, transportation, and building sectors with 30%, 11%, and 3%, respectively. methane (ch4), nitrous oxide (n2o), and fluorinated gases are all significant ghgs in addition to carbon dioxide (co2). as a ghg, methane is roughly 25 times more potent than co2 (paolini et al., 2018; nevzorova and kutcherov, 2019; hasan et al., 2020). methane is produced in nature as a decomposition of plant and animal matter, but there are also natural sinks that remove excess methane (nevzorova and kutcherov, 2019; yasmin and grundmann, 2019; hasan et al., 2020). extra methane, on the other hand, is emitted as a result of human activity. human activities are thought to have already contributed to roughly 1°c of global warming over pre-industrial levels (ipcc, 2014). furthermore, high amounts of methane deplete ozone, reducing the earth's protection against uv rays from the sun. anthropogenic methane is produced through waste (for example, landfill gas, municipal wastewater, and solid waste), agriculture (e.g. livestock), and industry (e.g. fossil fuel production). the methane produced by these sources may be utilized to make biogas, lowering ghg emissions while conserving energy and material resources. biogas has a high calorific value and may be used to substitute coal, oil, and natural gas, which can assist to reduce ghg emissions. biogas energy generation has the potential to turn a "costly problem" into a "profitable solution" (nevzorova and kutcherov, 2019; yasmin and grundmann, 2019; hasan et al., 2020). biogas can be utilized efficiently in simple gas stoves for cooking as well as lamps for lighting. furthermore, because of its high phosphorus content, biogas sludge may be used to produce biofertiliser for farms, which is predicted to minimize the need of chemical fertilizers and pesticides (luostarinen et al., 2009). some of the biogas producing materials (substrates) range from animal dung to household, agricultural and industrial wastes (akinbami et al., 2001). the agriculture sector has the most underutilized resources for biogas generation (nevzorova and kutcherov, 2019). animal husbandry is the primary cause of pollution in rural regions. unorganized emissions from collecting ponds and manure storage facilities, which emit hazardous chemicals, are the primary causes of pollution in this sector (hasan et al., 2020). the anaerobic treatment of animal waste in biogas plants offers numerous advantages, including a significant decrease in environmental pollution and pathogens, the removal of odors associated with livestock production, and a reduction in hazardous emissions into the atmosphere. biogas is produced during the anaerobic fermentation process, which also disinfects the waste. anaerobic fermentation of animal wastes might fulfill the energy demands of the husbandry sectors entirely or substantially, while also creating important organic fertilizers that can greatly lower the operational costs of biogas facilities. biogas, unlike biodiesel and bioethanol, is mostly created from organic waste and does not contribute to issues such as food scarcity or biodiversity loss. as a result, biogas is a more ethical alternative for energy generation (rittmann, 2008; manon and bermúdez, 2016; chala et al., 2018; faisal et al., 2018). rising greenhouse gas emissions, increasing consumption, water pollution, diminishing soil fertility, poor waste management, and deforestation are all consequences of inefficient use of natural resources across the world. biogas as an energy source is an essential component in the chain of actions to address these issues. however, realizing the full potential of biogas is taking time, and adoption varies depending on the available sources. as a result, biogas energy supply is typically relatively low when compared to other bioenergy sources (figure 2). ethiopia's economy is one of the fastest growing in africa, but it has one of the world's poorest access to modern energy supplies. the majority of ethiopia's population lives in rural areas and is heavily reliant on agriculture; biomass (biomass of wood, solid, and agricultural wastes) is the primary source of energy for ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 80 this rural population, accounting for approximately 87% of total energy supply (berhanu et al., 2017). nonetheless, the current energy systems in rural and urban areas differ significantly. almost all rural households use traditional biomass for cooking and baking, whereas nearly 90% of urban residents use electricity for lighting. ethiopia has enormous biomass energy potential, such as biogas, but it is being underutilized. figure 2: 2018 product shares in world renewable energy supply. despite its reliance on traditional energy sources, the country is gradually shifting away from nonrenewable energy sources and toward a clean, renewable energy supply. energy demand is currently increasing at an alarming rate due to the fast-growing economy and flourishing infrastructures (berhanu et al., 2017). as a result, at its best, finding an alternative energy source to overcome the issues associated with traditional biomass energy sources could be advocated. therefore, it is critical to understand the major problems that are presently impeding the widespread adoption of biogas as a source of energy, as well as potential solutions. while there have been some studies focused on the challenges and prospects of renewable energy in general (toklu, 2017; tiruye et al., 2021), and on biogas in specific locations (etsay et al., 2017; nevzorova and kutcherov, 2019; yasmin and grundmann, 2019; hasan et al., 2020; shallo et al., 2020). there has been no current, comprehensive review of the challenges and possible solutions to the increased use of biogas in ethiopia. to remedy this gap, the purpose of this article is to give a comprehensive and in-depth assessment of the challenges and solutions in biogas technology adoption in ethiopia. 2. biogas: composition, production and applications 2.1.biogas sources and composition biogas is a fuel that is generated when microorganisms degrade organic matter anaerobically (surendra et al., 2014). similarly, ehiri et al., (2014) described biogas as a fuel that is produced when microbes digest organic matter in the absence of oxygen(ehiri et al., 2014). organic matter is referred to as substrate and must be biodegradable, for example, domestic waste, primarily kitchen and sewage waste (municipal waste), crop residues and food processing byproducts, and animal dung, such as cow dung, poultry droppings, and pig dungs, among others (figure 3). however, the definition of biogas makes it abundantly clear that the primary source of biogas is organic matter. figure 3: classification of biogas sources. ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 81 table 1: chemical composition of biogas and properties of components (surendra et al., 2014). components concentration properties ch4 50–75% (v/v) energy carrier co2 25–50% (v/v) decrease heating value corrosive, especially in presence of moisture h2s 0–5000 ppm(v/v) corrosive sulfur dioxide emission during combustion nh3 0–500 ppm(v/v) nox – emissions during combustion n2 0–5% (v/v) decreases heating value water vapor 1–5% (v/v) facilitate corrosion in presence of co2 and sulfur dioxide (so2) biogas composition varies according to the type of feedstock used and the operating conditions of the digester. in general, biogas contains between 50% and 75% ch4 and 25%–50% co2, as well as trace amounts of water vapour (h2o), hydrogen sulphide (h2s), and ammonia (nh3). table 1 summarises the typical compositions of raw biogas and the properties of its constituents. only ch4 contributes to the heating value of biogas. for instance, 1 m3 of raw biogas containing 60% ch4 has a heating value of 21.5 mj (5.97 kwh of electricity equivalent) per m3, compared to 35.8 mj (9.94 kwh electricity equivalent) per m3 of pure ch4 at standard temperature and pressure (surendra et al., 2014). 2.2.biogas production the formation of biogas is the result of a series of linked process steps in which the initial substance is repeatedly broken down into smaller units. each individual step involves a different group of microorganisms. these organisms decompose the byproducts of previous steps in a sequential manner. figure 4 depicts a simplified diagram of the anaerobic digester (ad) process, highlighting the four main process steps: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. in the digester tank, the process steps depicted in figure 4 run in parallel in both time and space. the slowest reaction in the chain determines the speed of the total decomposition process. hydrolysis is the determining process in the case of biogas plants processing vegetable substrates containing cellulose, hemicellulose, and lignin. biogas is produced in small amounts during hydrolysis. biogas production peaks during methanogenesis (seadi et al., 2008). figure 4: major stages of biomethanation process (surendra et al. 2014). ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 82 2.2.1. hydrolysis theoretically, hydrolysis is the first step in ad, during which complex organic matter (polymers) is decomposed into smaller units (monoand oligomers). polymers such as carbohydrates, lipids, nucleic acids, and proteins are hydrolyzed and converted into glucose, glycerol, purines, and pyridines. hydrolytic microorganisms produce hydrolytic enzymes, which degrade biopolymers into simpler and more soluble compounds, as shown below (seadi et al., 2008): hydrolysis is carried out by exoenzymes produced by the microorganisms that decompose the undissolved particulate material, which involves a wide range of microorganisms. the hydrolysis products are further decomposed and used for metabolic processes by the microorganisms involved. 2.2.2. acidogenesis acidogenic (fermentative) bacteria convert hydrolysis products into methanogenic substrates during acidogenesis. simple sugars, amino acids, and fatty acids are degraded into acetate, carbon dioxide, and hydrogen (70%), as well as volatile fatty acids (vfa) and alcohols (30%). 2.2.3. acetogenesis during acetogenesis, acidogenesis products that cannot be directly converted to methane by methanogenic bacteria are converted into methanogenic substrates. vfa and alcohols are oxidized to produce methanogenic substrates such as acetate, hydrogen, and carbon dioxide. vfas and alcohols with carbon chains longer than two units are oxidized to form acetate and hydrogen. the partial pressure of hydrogen rises as it is produced. this is a "waste product" of acetogenesis that inhibits the metabolism of acetogenic bacteria. hydrogen is converted into methane during methanogenesis. acetogenesis and methanogenesis typically occur in tandem as a symbiotic relationship between two groups of organisms. 2.2.4. methanogenesis methanogenic bacteria are responsible for the production of methane and carbon dioxide from intermediate products. according to the following equations, 70% of the formed methane comes from acetate, while the remaining 30% comes from the conversion of hydrogen (h) and carbon dioxide (co2) (seadi et al. 2008). methanogenesis is a critical step in the anaerobic digestion process since it is the slowest biochemical reaction. the operation conditions have a significant impact on methanogenesis. factors influencing the methanogenesis process include feedstock composition, feeding rate, temperature, and ph. overloading the digester, temperature changes, or a large entry of oxygen can all result in the cessation of methane production. 2.3.anaerobic digester parameters some critical parameters influence the efficiency of ad, so it is critical that appropriate conditions for anaerobic microorganisms are supplied. conditions such as oxygen starvation, constant temperature, phvalue, nutrient supply, stirring intensity, and the presence and amount of inhibitors (e.g. ammonia) all have a significant impact on the growth and activity of anaerobic microorganisms. because methane bacteria are anaerobes, the presence of oxygen in the digestion process must be strictly avoided (seadi et al., 2008; bhajani, 2018; panigrahi and dubey, 2019; sathish et al., 2019). 2.3.1. temperature the ad process can occur at three different temperatures, which are classified as psychrophilic (below 25oc), mesophilic (25oc 45oc), and thermophilic (45oc 70oc). the process temperature and the hrt have a direct relationship (table 2) (seadi et al., 2008; bhajani, 2018; panigrahi and dubey, 2019; sathish et al., 2019). temperature stability is critical for ad. in practice, the operation temperature is chosen with the feedstock in mind, and the required process temperature is usually given by floor or wall heating systems inside the ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 83 digester. many modern biogas plants operate at thermophilic process temperatures because the thermophilic process offers numerous advantages over mesophilic and psychrophilic processes (table 3) (seadi et al., 2008; bhajani, 2018; panigrahi and dubey, 2019; sathish et al., 2019). table 1: temperature range and typical retention times thermal stage process temperatures minimum retention time psychrophilic < 20 °c 70 to 80 days mesophilic 30 to 42 °c 30 to 40 days thermophilic 43 to 55 °c 15 to 20 days table 2: advantages and disadvantages of the thermophilic process advantages disadvantages  effective destruction of pathogens  higher growth rate of methanogenic bacteria at a higher temperature  reduced retention time, making the process faster and more efficient  improved digestibility and availability of substrates  better degradation of solid substrates and better substrate utilization  better possibility for separating liquid and solid fractions  larger degree of imbalance  larger energy demand due to high temperature  higher risk of ammonia inhibition the toxicity of ammonia is affected by the operating temperature. ammonia toxicity increases with temperature and can be alleviated by lowering the process temperature. when the temperature is reduced to 50°c or lower, the growth rate of thermophilic microorganisms drops dramatically, and there is a risk of microbial population washout due to a growth rate lower than the actual hrt. because of the growth rates of thermophilic organisms, a well-functioning digester can be loaded to a greater extent or operated at a lower hrt than a mesophilic one (seadi et al. 2008; bhajani 2018; panigrahi and dubey 2019; sathish et al. 2019). 2.3.2. ph-values and optimum intervals the ph-value is a measure of the acidity/alkalinity of a solution (or, in the case of ad, a substrate mixture). the ph of the ad substrate affects the growth of methanogenic microorganisms as well as the dissociation of some important compounds for the ad process (ammonia, sulphide, organic acids). experience has shown that methane formation occurs within a relatively narrow ph interval, ranging from about 5.5 to 8.5, with most methanogens preferring a ph range of 7.0-8.0. acidogenic microorganisms typically have a lower optimum ph value. the ideal ph range for mesophilic digestion is between 6.5 and 8.0, and the process is severely hampered if the ph falls below 6.0 or rises above 8.3 (seadi et al., 2008). the solubility of carbon dioxide in water decreases as temperature rises. as dissolved carbon dioxide reacts with water to form carbonic acid, the ph of thermophilic digesters is higher than that of mesophilic ones. ammonia produced during protein degradation or the presence of ammonia in the feed stream can raise the ph value, whereas vfa accumulation lowers the ph value (seadi et al., 2008; bhajani, 2018; panigrahi and dubey, 2019; sathish et al., 2019). the bicarbonate buffer system primarily controls the ph value in anaerobic reactors. as a result, the ph value inside digesters is affected by co2 partial pressure as well as the concentration of alkaline and acid components in the liquid phase. if base or acid accumulates, the buffer capacity counteracts these ph changes to a certain extent. when the system's buffer capacity is exceeded, drastic changes in ph occur, completely inhibiting the ad process. as a result, the ph-value should not be used as a stand-alone process monitoring parameter (seadi et al., 2008). 2.3.3. volatile fatty acids (vfa) the concentration of intermediate products such as vfa reflects the stability of the ad process. the vfa are acidogenesis intermediate compounds (acetate, propionate, butyrate, lactate) with a carbon chain of up to six atoms. in most cases, ad process instability results in vfa accumulation inside the digester, which can cause a ph drop. however, due to the buffer capacity of the digester and the biomass types contained ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 84 in it, the accumulation of vfa will not always be expressed by a drop in ph value. animal manure, for example, has an excess of alkalinity, which means that vfa accumulation must exceed a certain threshold before it can be detected by a significant decrease in ph value. the vfa concentration in the digester would be so high at this point that the ad process would be severely inhibited. as a result, as with ph, vfa concentration cannot be recommended as a stand-alone process monitoring parameter (seadi et al., 2008; bhajani, 2018; panigrahi and dubey, 2019; sathish et al., 2019). 2.3.4. ammonia ammonia (nh3) is an important compound that plays an important role in the ad process. nh3 is an important nutrient that serves as a precursor to foods and fertilizers. it is typically encountered as a gas with a pungent odor. proteins are the primary ammonia source for the ad process. process inhibition is thought to be caused by excessive ammonia concentrations inside the digester, particularly free ammonia (the unionized form of ammonia). because of the high ammonia concentration originating from urine, this is a common ad of animal slurries. ammonia concentrations should be kept below 80 mg/l to have an inhibitory effect (seadi et al. 2008). ammonia inhibition is especially sensitive to methanogenic bacteria. because the concentration of free ammonia is directly proportional to temperature, there is a greater risk of ammonia inhibition in thermophilic ad processes compared to mesophilic ones (seadi et al. 2008; bhajani 2018; panigrahi and dubey 2019; sathish et al. 2019). 2.3.5. macroand micronutrients (trace elements) and toxic compounds microelements (trace elements) such as iron, nickel, cobalt, selenium, molybdenum, or tungsten are as important for the growth and survival of ad microorganisms as macronutrients such as carbon, nitrogen, phosphorus, and sulfur. inadequate nutrient and trace element provision, as well as excessive substrate digestibility, can cause inhibition and disturbances in the ad process. the presence of toxic compounds is another factor influencing the activity of anaerobic microorganisms. they can be introduced into the ad system alongside the feedstock or generated during the process. the application of threshold values for toxic compounds is difficult, on the one hand because these materials are frequently bound by chemical processes, and on the other hand because anaerobic microorganisms can adapt to environmental conditions, including the presence of toxic compounds, within certain limits (seadi et al., 2008). 2.3.6. organic load a biogas plant's design and operation are influenced by both economic and technical factors. to achieve the highest biogas yield through complete substrate digestion, a long retention time of the substrate inside the digester and a correspondingly large digester size would be required. in practice, the choice of system design (digester size and type) or applicable retention time is always based on a trade-off between maximizing biogas yield and maintaining a justifiable plant economy. the organic load is an important operational parameter in this regard, as it indicates how much organic dry matter can be fed into the digester per volume and time unit (seadi et al., 2008). 2.3.7. hydraulic retention time (hrt) the hydraulic retention time is an important parameter to consider when designing a biogas digester (hrt). the hrt is the average time interval during which the substrate remains in the digester tank. hrt is proportional to digester volume and substrate fed per time unit. the retention time must be long enough to ensure that the amount of microorganisms removed with the effluent (digestate) is not greater than the amount of microorganisms reproduced. anaerobic bacteria typically duplicate every 10 days or more. a short hrt allows for a higher substrate flow rate but a lower gas yield. as a result, it is critical to tailor the hrt to the specific decomposition rate of the substrates used. the required digester volume can be calculated using the targeted hrt, the daily feedstock input, and the substrate decomposition rate (seadi et al., 2008). 2.4.biogas applications biogas is a renewable energy carrier that has the potential to be used for a variety of end uses, including heating, combined heat and power (chp) generation, transportation fuel (after being upgraded to biomethane), and natural gas quality for a variety of end uses (figure 5). however, in developing nations, biogas is largely used for cooking and lighting through household-scale digesters. this is because the most ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 85 common digester in poor nations is between 2 and 10 m3, and the volume of biogas produced by such a digester is insufficient to support chp or purification into biomethane for other end uses. it should be emphasised, however, that biogas generated by largescale institutional facilities is being used to generate energy in some developing nations via fuel cells or combined heat and power (chp) engines, similar to methods used in affluent countries. after cooking, lighting is the second most prevalent application of biogas, particularly in areas without access to the electrical grid. biogas is used to power lights using customised gas mantle lamps that burn approximately 0.07–0.14 m3 of biogas per hour and operate satisfactorily at gas pressures ranging from 70–84 mm of water. figure 5 illustrates the flow of feedstocks through the ad system to produce biogas and digestate. biogas recovery and utilization from ad systems often creates significant value in new economic, energy, environmental benefits by managing and converting organic waste into energy and beneficial uses of digestate. unlike traditional organic waste disposal and manure storage systems, modern ad/biogas systems can be designed to increase and optimize the production of biogas and energy generation, among many other benefits. benefits of ad/biogas systems include, but are not limited to, generation of various types of energy, including baseload renewable energy generation; odor minimization; generation of nutrient rich digestate; improving the environment by minimizing waste; among many others. the potential and problems associated with the use of biogas technologies are summarized in table 4. figure 1: basic anaerobic digestion (ad)/biogas system flow diagram (epa, 2008). ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 86 table 3: advantages and disadvantages of biogas (bhardwaj and das, 2017) advantages of biogas disadvantages of biogas it is a renewable source of energy: the only time when biogas will be depleted is when the production of any kind of waste is stopped. also, it is a free source of energy. little technology advancements: very few technological advancements have been made or introduced for streamlining and making the process cost-effective and hence the systems that are currently used are not efficient enough. non-polluting: biogas is considered to being nonpolluting. the resources are conserved by not consuming any further fuel since the production of biogas does not require any oxygen. it also reduces deforestation and any sort of indoor air pollution. it consists of impurities: biogas goes through many refining processes and yet contains several impurities. the metals in an engine can start corroding if this biogas full of impurities is used as a fuel after compressing the biogas. it reduces landfills: there is a decrease in soil and water pollution since it uses up the waste in landfills and in dumps as well. biogas is not attractive on large scale: large scale usage of biogas is not economically viable. enhancing the efficiency of biogas systems is very difficult as well. a large number of jobs are obtained: due to the biogas plant setups, a major number of work opportunities get created for thousands of people. biogas is unstable: when methane comes in contact with oxygen, biogas tends to become flammable. this happens because biogas is unstable and hence it is vulnerable to explosions the setup of a biogas plant requires little capital investment and is also easy when set up in a small scale. production of biogas takes place by utilizing the gases which are produced by the landfills and hence the greenhouse effect is reduced. biogas slurry can used as organic fertilizer: in contrast to composting and direct burning, biogas digester provides both fuel and fertilizer, rather than simply one or the other. 3. methodology the data was gathered from journals, site visits to biogas digesters, and questionnaires distributed to biogas installers. site visits for biogas digesters resulted in the recording of observations. the data on issues and challenges with biogas technology was gathered by the authors and from various stakeholders during the installation of some biogas digesters through questionnaires, a literature review, and site visits. 4. biogas technology dissemination and current status in ethiopia 4.1.biogas dissemination 4.1.1. before 1980 biogas was first introduced in ethiopia by ambo agricultural college around 1957 to supply the energy for welding agricultural tools (abadi et al., 2017; sime et al., 2020a; tesfay et al., 2021). the system that was installed was a batch digester unit, in which all of the raw materials (water and waste materials) were added simultaneously, allowed to break down for three to four weeks, and then the gas and bio-slurry were removed simultaneously (abadi et al., 2017; sime et al., 2020a; tesfay et al., 2021). this technology's defect is that it ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 87 cannot continuously supply methane gas because continuous slurry feeding was not allowed, which renders it ineffective and unacceptable. however, ethiopian government agencies and the food and agriculture organization (fao) have been working for several years to promote and accelerate this type of technology in the country (smith 2011). fao introduced two biogas plants as pilot projects in the 1970s to further promote the technology in ethiopia (abadi et al., 2017; sime et al., 2020a; tesfay et al., 2021). 4.1.2. from 1980 to 2000 during this time, private and government agencies built over 1000 biogas plants ranging in size from 2.5 to 200 m3 in various communities across the country (abadi et al., 2017; sime et al., 2020a). this implementation period was devoted to demonstrating the efficacy of various biogas technologies (tesfay et al., 2021). various models, including fixed dome, indian floating drum, and bag digesters, were tested during this time period. the cost-benefit analysis of the fixed dome biogas model in ethiopia shows that its adoption has a significant positive net present value for both households that collect their own energy sources and those that purchase all of their energy sources. however, nearly 60% of the installations were inoperable (abadi et al., 2017). in general, the fixed dome digester performed poorly and had little success in implementing a market-oriented, self-sustaining biogas program. these shortcomings of the fixed dome digester hampered the spread of biogas technology and discouraged potential users. however, this generation has paved the way for the country's third biogas technology program. 4.1.3. from 2000 to date and national biogas program ethiopia (nbpe) ethiopian and german governments collaborated at the end of the 1990s to update ethiopian biogas technology development. as a result, 60 fixed-dome biogas digesters were built in addis ababa and adama between 1999 and 2002 (tesfay et al., 2021). this generation's implementation also includes the local construction of the biogas digester and ensuring promotion through successful installation and close proximity. this prompted and motivated the locals to build more biogas plants. furthermore, according to the snv report, approximately 150 biogas digesters were built in tigray in 2005 (sime et al., 2020b; tesfay et al., 2021). ethiopia began implementing a nationally planned biogas program in 2009 (manon and bermúdez, 2016; gezahegn et al., 2018; gabisa and gheewala, 2019; sime et al., 2020a). the national biogas program ethiopia (nbpe) is divided into two phases: phase 1 and phase 2. nbpe1 was implemented in four regions (amhara, oromia, snnpr and tigray) from 2009 to 2013. nbpe2 runs in the same regions from 2014 to 2019. the nbpe1 and nbpe2 were funded by the dutch/dgis and ethiopian governments, respectively. additional four regions (somalia, benshangule gumuz, gambela, and afar) have been included in the nbpe+ phase (2017-2022). the european union (eu) and the ethiopian government provided funding for nbpe+. promotion and marketing, training, quality management, research and development, monitoring and evaluation, institutional support, extension, and gender mainstreaming are the eight major components of nbpe activities. the overall goal of the nbpes is to facilitate the expansion of access to modern energy services for rural households and communities through the introduction and development of biogas energy. as a result, the goal of this program is to provide clean and safe energy for cooking and lighting in these communities. this strategy has the potential to replace the use of wood and charcoal, as well as chemical fertilizer, in order to improve agricultural, health, and livelihood conditions in rural areas (sime et al., 2020b). furthermore, it aimed to develop commercially viable domestic biogas technology to ensure the country's biogas plants operate continuously. the program's specific goals were to: (1) attract and strengthen institutions and organizations for the development of a national biogas sector; (2) build 14,000 biogas plants in chosen regions over the course of five years; (3) ensure that installed biogas plants are still operating under the nbpe; and (4) maximize the advantages of all biogas plants installed through private sector competition, with the expectation that potential users would gain from lower costs and the better efficiency (h tesfay et al. 2021). national biogas program ethiopia phase one (nbpe1): the five-year pilot implementation phase, ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 88 which is the first phase of the nbpe, began in 2009. as shown in table 5, the program has distributed biogas plants in 18 chosen districts (woredas) in the amhara, snnp, oromia, and tigray regions (abadi et al. 2017). these districts were chosen based on factors such as the density of people and livestock, the loss of vegetative cover, the level of education and technological adoption in the districts, the availability of relatively welldocumented data, and the consumption of woody biomass that exceeds annual production in more than two-thirds of the districts (manon and bermúdez 2016; mengistu et al. 2016; berhe et al. 2017; kelebe 2018; sime et al. 2020b). at the end of phase one implementation, the program had built 8063 biogas plants, representing approximately 57.6 % of the initial planned 14000 installations in 163 sub-districts. the number of installed plants in amhara (33 sub-districts), snnp (23 sub-districts), tigray (29 sub-districts), and oromia (78 sub-districts) is 1892, 1699, 2001, and 2480, respectively (abpp, 2017; trbpcu, 2017), with various biogas digester sizes (4, 6, 8, and 10 m3) and fixed dome model (manon and bermúdez 2016; mengistu et al. 2016; berhe et al. 2017; kelebe 2018; sime et al. 2020b). figure 6 depicts the annual installed biogas plants in the four regions. table 2 shows the districts that have been chosen to implement nbpe1 (h tesfay et al. 2021). figure 6: biogas distribution in ethiopia during nbpe1 implementation (h tesfay et al. 2021). table 4: selected woredas to implement nbpe1 (tesfay et al. 2021). regions woredas oromia ada’a, dugda bora, hetosa, ambo, kuyu amhara bahir dar zuria, dembia, gonder zuria, fogera, dangla snnp dale, mareko, meskan, arba minch zuria, derashe special woreda tigray hintalo wajorat, raya azebo, western tigray many factors contribute to the 42.4 % failure to meet the nbpe1 target (manon and bermúdez, 2016; mengistu et al., 2016; berhe et al., 2017; kelebe, 2018; sime et al., 2020b). this includes: (1) rising construction material costs, which raise the per digester cost, (2) inadequate or lack of skilled labor and expert’s (3) low commitment of stakeholders at the regional level and lack of credit facilities in some regions because the beneficial are not financially well organized, (4) inadequate follow-up service after installation and commissioning, (5) the technology's application is limited to lighting and light cooking and (6) available alternative energy sources to meet their energy needs (manon and bermúdez, 2016; mengistu et al., 2016; berhe et al., 2017; kelebe, 2018; sime et al., 2020b). national biogas program ethiopia (nbpe2)-phase two: the second phase (2014-2019) is known as the scale up program, and it aims to spread biogas by incorporating the lessons learned during the first phase. specific goals for nbpe2 include: (1) scaling up the distribution of 20,000 biogas digesters, (2) scaling up the distribution of biogas appliances for household cooking, (3) pilot installation of larger size digesters, (4) ensuring long-term sustainability of biogas as a renewable energy, and (5) participation of alternative implementing partners and private microfinance institutions (manon and bermúdez, 2016; mengistu et al., 2016; berhe et al., 2017; kelebe, 2018; sime et al., 2020b). during this phase, the program concentrated on the four regions chosen in phase one. from 2014 to 2016, the total number of biogas plants installed in the four regions is shown in figure 7. total biogas installations in the four regions were 7330 in these three years, with an annual average of 2443 plants. it will be interesting to see if this trend continues into 2019. ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 89 nbpe2 has achieved approximately 73% of the target number of installations. this would be an improvement over the phase one achievement rate (sime et al., 2020a). a national biogas dissemination scale-up program (nbpe+) is currently being introduced by the nbpe, which will continue to 2022 and covers all regional states of the country (sime et al., 2020b). figure 2: installed biogas plants between 2014 and 2016. 4.2. current status of biogas technology in ethiopia the number of digesters has significantly increased during phases i and ii of the national biogas program, particularly in the four regions that were chosen to implement nbpe. 15,403 digesters have been installed overall during this time, which is about 45.3% of the target (34 000) for the two nbpe phases. in ethiopia, biogas technology is primarily used for lighting and cooking. about 43% of digester owners use biogas for both lighting and cooking, compared to 10.8% and 3.2% who use it exclusively for cooking and lighting, respectively. on the other hand, incomplete installation and technical issues with the biogas plant have prevented 43% of biogas adopters from using it (berhe et al., 2017). table 6 displays the cumulative size of biogas installation and distribution in ethiopia. the efforts to install bio-digesters in the remaining regions of the country were extremely minimal in comparison to the four regions in phases i and ii. according to snv's baseline study, 6 m3 and 8 m3 biogas digester sizes had 68 % and 25% of all cumulative national installations, respectively, of the installations. as can be seen, there were differences in the size distributions between the regions. the least number of biogas digesters of the four common sizes (4 to 10m3) have been installed across all regions. in a similar vein, biodigesters larger than 10 m3 were not common in all regions, with the exception of oromiya, which has 67 % of all installations in this size nationwide. it was discovered that different geographical areas had different bio-digester functionality rates. as shown in figure 8 (tesfay et al., 2021)., the snv baseline study estimates that 54 % of the country's biogas digesters are functional. slurry feeding issues and technical difficulties were found to be the main barriers, although various researchers gave various explanations for why biogas digesters weren't functional (seboka, 2019; marie et al., 2021; fentie and sime, 2022; tekle and sime, 2022). the irregularity of feeding, overfeeding, and insufficient initial feeding are the causes of the feeding issues. technical issues are also classified as issues with the construction process, such as digester technical faults like a cracked dome, a drainage issue, or an incomplete foundation. according to nbpe+ (2018), additional reasons for non-functionality include: (i) lack of spare parts or accessories, (ii) a water supply issue, (iii) relocation of users or due to an owner's passing, (iv) the sale of the owner's cattle, and (v) promotion issues are just a few examples. 5. challenges to biogas development in ethiopia in much of rural ethiopia, access to modern forms of energy is irregular or non-existent. as a result, the population relies heavily on a limited and rapidly diminishing supply of solid fuels like as wood and charcoal for cooking and lighting. additionally, dung and crop waste are being used as substitute fuels, when they may be better utilised to improve soil nutrients and contribute positively to agricultural production. the broad use of biogas technology and bio-digester functionality is constrained by issues such as economic instability, a lack of technical skills, poverty and illiteracy, societal challenges, and institutional constraints (mukumba et al., 2016). these are discussed in greater detail below. ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 90 table 5: installation of biogas digesters in ethiopia, until march 2017 (h tesfay et al. 2021). size oromia tigray amhara snnp somalia benshangule gumuz gambela afar total 4 m3 97 112 17 1 227 6 m3 2059 4146 1933 2542 10 7 10,697 8 m3 1400 20 1771 747 15 3953 10 m3 577 44 122 118 861 total 4133 4210 3938 3424 10 7 1 15,738 figure 3: biogas digester functionality percentage of regions (h tesfay et al. 2021). 5.1. expensive initial investment in biogas digesters although biogas technology has the potential to meet ethiopia's energy needs, particularly those of rural residents, the design and installation of digesters are costly. the initial investment cost is a significant barrier to biogas uptake in ethiopia, regardless of government support initiatives for renewable energy technologies. for example, the cost of installing an 8 m3 fixed dome digester is at least 570 usd. however, the government and donations cover approximately 40% of this expense. additionally, labor is required for daily operation, digester maintenance, supervision, slurry feeding, storage, and disposal. the availability of this labor decides whether or not the digester will operate at full capacity. daily biogas requirements increase in direct proportion to family size, and as a result, the expense increases as well. reduced installation costs without sacrificing quality or performance could make biodigesters more accessible to users (rupf et al., 2015; mukumba et al., 2016; nevzorova and kutcherov, 2019). 5.2.biogas substrates availability in rural ethiopia, cow manure is the primary biogas substrate. for long-term functioning, the amount of substrate entering the digesters should be stable. biogas digesters are established under the assumption of a steady daily or weekly supply of substrate. numerous methane digesters fail owing to a lack of substrate and inconsistency in feeding due to the scarcity of manure. collecting dung is difficult, especially when combined with water to dilute the substrate. additionally, healthy cattle nutrition is lacking in order to obtain nutritious cow manure for biogas production. to many farmers, the use of other agricultural waste products as substrates for digesters, such as human excreta, poultry dung, pig manure, donkey dung, and garden wastes, is inadequate. as a result, many biogas digesters remain underfed, resulting in the inability to produce methane. 5.3.lack of research on biogas technology ethiopia has a lack of biogas technology research, despite the fact that the country has installed a large number of digesters. there is no data available on the amount of methane produced by installed biogas digesters or on methods for enhancing the quality of the methane. often, data collection on failing digesters is impeded by certain techniques. additionally, biogas specialists' research on biogas technology is limited by a lack of funding, which has a detrimental impact on biogas dissemination programmes. additional research is required to determine the best methods for utilising the biogas from the activated sewage treatment works for the benefit of the country's residents. ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 91 5.4.public awareness campaign education is one of the most significant impediments to the advancement of biogas technology in developing country, particularly ethiopia. it is critical to educate the community about the economic, social, health, and environmental benefits of biogas technology in order to establish a successful and sustainable biogas system. rural communities in the country require proper education to understand the value of biogas energy in comparison to other energy sources. additionally, there is no biogas technology instruction in primary, secondary, or tertiary schools, and as a result, many rural people are unaware of the social and economic benefits of this new technology and continue to use firewood even when biogas digesters are accessible. 5.5.inadequate construction and maintenance expertise inadequate skills for biogas digester building and maintenance is another impediment to the spread of biogas technology in the country. there are few or no technical or vocational schools or colleges that teach students how to install and maintain biogas digesters. numerous biogas initiatives in the country have failed owing to a lack of effective management as a result of a lack of education. 5.6.biogas has a low efficiency biogas is inefficient as a fuel when compared to fossil fuels such as diesel and petrol. the methods to improve its efficiency so as to run internal combustion engines are lacking. numerous biogas digesters have been closed due to farmers' lack of experience and cooperation from biogas professionals in optimising biogas's calorific value. 5.7.minimal biogasa application the amount of substrate available to a digester dictates its size. the digesters constructed in various rural villages have not been sized according to substrate availability. the digesters are identical in size regardless of the substrates available to each family. although the digesters' sizes should fluctuate according on substrate availability, this is not the case. these digesters are frequently malnourished. in general, a household with two cows may operate a 4 m3 digester; a home with four cows can operate a 6 m3 digester; and a household with six cows can operate an 8 m3 digester (mukumba et al. 2016). 5.8.bio-slurry composition and management bio-slurry as an organic fertiliser is environmentally safe, contains no toxins or irritants, and may easily replace chemical fertilisers. bio-slurry is a 100% organic fertiliser most ideal for organic farming. additionally, the lack of attention paid to the biogas technology's bioslurry aspects was due to the ministry of agriculture's minimal involvement. the primary technical issue with bio-slurry management was the outflow of bio-slurry prior to fermentation, the backflow of bio-slurry into digesters, and the vulnerability of bioslurry pits to flooding during periods of heavy rain. as a result of outflow, there is a risk to health from the foul odours generated during the preparation, transportation, and application of bio-slurry. due to insufficient training, user households lacked the necessary technical abilities for preparing and using bio-slurry. the other difficulty was that the rate of bioslurry application per hectare for various crops had never been documented in ethiopia, which could have boosted the bio-reputation slurry's and expanded its use in crop production. additionally, there is a need to campaign for the promotion of biogas's numerous uses beyond cooking and lighting, such as an integrated farming method that incorporates biogas and bio-slurry. 6. solutions to biogas challenges 6.1.extensive biogas research the national biogas programme was launched in 2009 with the goal of establishing a commercially sustainable domestic biogas sector. the ethiopian government, in partnership with the netherlands development organization, designed the project, which is coordinated by the ministry of water and energy (snv). the government should develop training institutes in each region to educate citizens about biogas technology. extensive research on biogas technology should be conducted, focusing on the following areas: biogas technology constraints in ethiopia, new biogas designs, model equations for optimum methane yield, techno-economic analysis of rural biogas digesters, prefeasibility and feasibility studies of urban biogas digesters, replacing firewood with biogas for cooking and in electricity generation in rural areas, most suitable ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 92 inoculums for biogas production, and biogas as a fuel source for power generation. in the country, research on biomass as a source of energy is still in its infancy. at the moment, the government relies heavily on research conducted outside of africa. when considering the country's present energy needs, new understanding in biogas technology is required. 6.2.adequate biogas user education to minimize biogas digester failures, the government, non-governmental groups, and biogas installers should train biogas users on feeding and maintaining biogas digesters (mukumba et al., 2016). many rural populations who rely on firewood have a limited understanding of the value of biogas as a source of energy, owing to the fact that they have an alternative source of energy. biogas digesters are constructed in many rural communities to produce biogas for heating and cooking needs, but not for electricity generation or transportation. through government backing, biogas installers and specialists must train biogas users on the handling of animal wastes, feeding, cleaning, the quantity of water to add to manure, and measures to minimize souring of the biogas digesters. the installation of biogas digesters in remote communities is perceived by biogas consumers as a research endeavor, not a community activity. thus, biogas users require adequate education to develop a sense of ownership over biogas projects in order to improve their economic, social, and health conditions. 6.3.substrates co-digestion numerous digesters installed in rural ethiopian communities employ cow manure as a substrate for biogas production. biogas produced from cow manure is extremely low in comparison to other wastes. wastes are not co-digested, resulting in minimal biogas yields. co-digestion of organic wastes requires the incorporation of a variety of substrates in variable amounts (mukumba et al. 2016). co-digestion is essential to maximize biogas production by promoting ammonia elimination during digestion. the mixing of multiple wastes benefits the anaerobic digestion process because it increases methane yield, improves stability, and facilitates waste management. additionally, such a system is more economically viable because it consolidates multiple streams into a single facility. when food waste and toilet waste are co-digested, the toilet waste's low carbon: nitrogen (c/n) ratio and biodegradability content are compensated for by the food waste's high values for those two parameters. thus, the major issue of ammonia toxicity caused by a low carbon/nitrogen ratio is avoided, and the low biogas output caused by a low biodegradable matter content is increased. as a result, co-digestion of wastes improves the quality of biogas. 6.4.enhancing biogas's calorific value to boost biogas's calorific value, it should be purified and upgraded to eliminate carbon dioxide, hydrogen sulphide, and water vapour. the biogas scrubbing unit will be divided into three subsystems: co2 separation, h2s separation, and moisture separation. purified biogas produced by the scrubbing units has roughly 95% methane, compared to biogas produced directly from cow dung-fed biogas digesters, which contains approximately 55% methane. the biogas, now referred to as bio-methane, has a high heating value (figure 9). ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 93 figure 4: biomethane versus anaerobic digestion. 6.5.designing digesters depending on the substrates available the biogas digesters that will be constructed in various communities should be developed in accordance with the substrate availability for each family. oversized biogas digesters result in the failure of the digester due to insufficient feed. the digester's size is also determined by the retention duration and temperature (mukumba et al., 2020). 7. conclusion for many years, humans have used biomass energy as a source of fuel. it is considered a renewable energy source because, unlike carbon-emitting fossil fuels, it is a carbon-neutral energy source. this is why there are breakthroughs and advancements in biomass energy, particularly in the current use of biomass as a source of energy in many countries. it is an important source of energy, accounting for more than 80% of ethiopia's energy consumption. despite the fact that ethiopia has a large potential for various alternative energy sources, electricity access is limited because the majority of the population lives in rural areas due to the country's dispersed population distribution. furthermore, because national grids were located far from rural residents, the majority of rural residents lacked daily access to electricity. the majority of rural societies rely on free woody biomass, crop residues, and livestock dung collection. as a result, they rely on traditional biomass energy sources such as burning wood, dung, and agricultural waste for cooking, heating, and lighting. currently, energy demand is increasing, while power generation supply should be balanced with demand. therefore, this review describes the current challenges and potential solutions to the widespread use of biogas as a source of energy in ethiopia. the country's biogas technology expansion faces a number of obstacles, including a high initial investment cost for biogas digesters, insufficient skills for biogas digester building and maintenance, and low biogas efficiency. additionally, it was noted that a lack of research on biogas technology is impeding the country's biogas digester expansion. it may be stated that the country's installed biogas digesters should be sized appropriately for the substrate available. additionally, the calorific value of the biogas should be increased by conversion to bio-methane, which can be utilized to power internal combustion engines and generator sets. additionally, community-based training about biogas production and use should be begun to minimize biogas digester failures. there is a need to completely engage and accelerate the spread of biogas digesters in the country by developing innovative digester designs and giving enough information to biogas users on biogas usage, maintenance, handling, and co-digestion optimization. we certainly hope that the contributions we have made to this review will be extremely helpful to researchers, educators, decision-makers, working professionals, ashenafi abebe & asfaw, natei . ethiop.j.sci.sustain.dev., vol. 9 (2), 2022 94 senior undergraduate and graduate students, and other people who are interested in pollution remediation and energy production and storage using renewable and affordable bio resources. reference abadi n, gebrehiwot k, techane a, nerea h (2017) links between biogas technology adoption and health status of households in rural tigray , northern ethiopia. energy policy, 101:284–292 akinbami jfk, ilori mo, oyebisi to, et al (2001) 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keno, daniel getahun debelo* adama science and technology university, school of applied natural science, department of applied biology, p. o. box 1888, adama, ethiopia * corresponding author, e-mail: daniel.debelo@astu.edu.et abstract yayo coffee forest biosphere reserve is part of the afromontane rainforest in southwestern ethiopia, and it is the center of origin for the most popular wild populations of arabica coffee (coffea arabica). the forest was designated as unesco biosphere reserve to conserve coffee genetic resources and overall biodiversity of the forest. the coffee forest is, however, threatened by different factors. the major objective of the study was to collect data on attitudes and perceptions of the community towards the biosphere reserve in general and threats to it in particular. data were collected through semi-structured interviews held with 212 (n = 1479) household heads selected randomly from 3 of the 5 gandas (ganda, in the local afan oromo language, is the lowest level of administrative body below district) which are considered by unesco as the most important transition zone in the biosphere reserve. data were analyzed using descriptive statistics. about 51 % of the respondents supported the establishment of the biosphere reserve. the respondents recognized the forest values like as home of wild coffee (100 %), source of fuel wood (99.6 %) and construction materials (95.7 %) and because of these values, 57.7 % of them agreed that the community has the responsibility to protect the forest from threats. all the respondents were aware of the presence of large-scale development projects like yayo coal mining industry and yayo fertilizer factory which were legally established around the forest, gaba hydropower dam, road construction and electric transmission line established legally inside the forest, and coffee plantation carried out illegally inside and around the forest (27 %) which have adverse effects on the biodiversity of the area if not properly managed. ninety-one percent of the respondents mentioned that there were conflicts between the management bodies of the biosphere reserve and the local community over timber logging (100 %), charcoal production (45.1 %), expansion of coffee plantation, and gain of no benefits/incentives from the government (92.5 %). understanding the main source of conflict is critical to the resolution of conflict. all the forest managing bodies found at different levels should give due attention in protecting the forest from anthropogenic activities such as farmland expansion and illegal extraction of forest products. keywords: attitude, biosphere reserve, conflict, perception, population growth, yayo 1. introduction biosphere reserves are natural protected areas included in a global network organized by the united nations educational, scientific, and cultural organization (unesco). participating countries propose land and water sites within their boundaries as potential biosphere reserves, and accepted sites are designated at the international level by unesco’s man and the biosphere reserve (mab). unesco’s mab program was launched in 1971 with the aim of promoting interdisciplinary research, training, and communications in the field of ecosystem conservation and the rational use of natural resources (oefcca and ofwe, 2018). http://www.ejssd.astu.edu/ mailto:daniel.debelo@astu.edu.et etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 80 the last update report of july 2018 of the directory of the world network of biosphere reserves shows that there are 686 world network of biosphere reserves in 122 countries, including 20 trans-boundary sites (http://www.unesco.org/new/en/natural-sciences/environment/ ecological-sciences/biosphere-reserves/world-network-wnbr/ wnbr). to date, there are five unesco registered biosphere reserves in ethiopia and these are yayo coffee forest biosphere reserve and kafa biosphere reserve registered in 2010, sheka biosphere reserve registered in 2012, lake tana biosphere reserve registered in 2015 (tesfu fekensa et al., 2018) and majang forest biosphere reserve registered in 2017 (oefcca and ofwe, 2018). yayo coffee forest biosphere reserve (ycfbr) is situated in ilu abba bora zone and buno-bedele zone of the oromia national regional state, southwestern ethiopia. the forest is part of the afromontane rainforest in southwestern ethiopia, and it is the center for arabica coffee (coffea arabica) which is globally a highly popular wild coffee species. the reserve is an important place for the conservation of the wild coffea arabica in particular but also the vast biodiversity living in the forest reserve in general. the reserve also includes afromontane biodiversity hotspots, important bird areas, archaeological sites, ritual sites, caves, and waterfalls (tilahun mulatu and abebe getahun, 2018). survey conducted by the international union for conservation of natural resources (iucn) on protected areas in 10 key forested countries found that only 1 % of protected areas were secure from threat (hayes and ostrom, 2005). ethiopian natural forest has been lost or degraded to a level of disturbed forest lands in the time span of 1971 to 1997 by 50 % (daba wirtu, 2000). reusing (1998) reported that 60 % of the ethiopian forest area has been modified or destroyed by anthropogenic influences such as new settlements, conversion to other land uses and timber extraction in the past three decades. about 2000 km2 of extremely fragmented rain forest remain in the country (zef and earo, 2002). forest cover in some parts of southwest ethiopia has decreased from 71 % to 48 % between the years of 1973 and 2005 (wakjira dereje and tadesse woldemariam, 2007). due to widespread human influence on the natural forest, larger portions of the existing forest areas have been planted by man and are hence secondary (kidane mengistu, 2002). the ever-increasing human population coupled with unwise land use and farming systems, un-sustainable forms of agricultural intensification, and catchment degradation has resulted in serious degradation of these important forest resources. these coupled with the impacts of climate change lead to economic destabilization and habitat destruction and loss. this calls for urgent conservation action undertakings in the yayo forest biocultural resources as a cure against the prevailing high risk and the resulting tremendous effects of overall yayo coffee forest biosphere reserve territory. to restore and sustain the ecological functioning of forest resources, the introduction of participatory sustainable biosphere reserve management and offering alternative use options for coffee forest resources in the proposed biosphere reserve area could be appropriate option (oefcca and ofwe, 2018). therefore, the aim of this study was to explore attitudes and perceptions of the local community towards forest values, conflicts, establishment, and conservation of the yayo coffee forest biosphere reserve. clear knowledge of factors influencing people’s perceptions and attitudes could be incorporated into a co-management approach for improving the relationship between the biosphere reserve and the local community. 2. materials and methods 2.1. the study area the ycfbr is located in the ilu abba bora and buno bedele zones in oromia national regional state, southwest ethiopia (figure 1). the site covers a total area of 167,021 hectares of biodiversity hotspots that has three management zones namely, core zone with (16.6%), buffer zone (12.9%) and transitional zone (70.5%) hectare area (tesfu fekensa et al., 2018). the entire biosphere reserve is stretched over six districts: doreni, yayo, bilo-nopa, algie-sachi, hurumu and chora. it is located between 8°0'42" and 8°44'23"n and 35°20'31" and 36°18'20"e. its elevation is between 1,100 and 2,337 meters above sea level. the most important landscapes of the biosphere were forest, agricultural lands, wetlands and running water, grazing lands and built-up areas (tadesse woldemariam, 2010). the biosphere reserve includes eastern afromontane biodiversity hotspot and important bird areas of http://www.unesco.org/new/en/natural-sciences/environment/%20ecological-sciences/biosphere-reserves/world-network-wnbr/%20wnbr http://www.unesco.org/new/en/natural-sciences/environment/%20ecological-sciences/biosphere-reserves/world-network-wnbr/%20wnbr http://www.unesco.org/new/en/natural-sciences/environment/%20ecological-sciences/biosphere-reserves/world-network-wnbr/%20wnbr etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 81 international significance and one of remnant montane rainforest fragments with wild coffee (coffea arabica) populations in the world (tesfu et al., 2018). the biosphere reserve was established to conserve coffee genetic resources and overall biodiversity of the forest (unesco, 2013). 2.2. study population and sampling techniques three gandas, wabo, gechi, and hamuma, were randomly selected from five gandas which were considered by unesco as the most important transition zone in the biosphere reserve. [in the local afan oromo language, ganda is the lowest level of administrative body below district, aanaa. kebele is an equivalent word to ganda in amharic language]. in total the number of households in the three gandas was 1479. data on attitudes and perceptions of the community towards the biosphere reserve in general and threats to it in particular, were collected through semi-structured interviews held with 212 (n = 1479) household heads selected randomly from 3 of the 5 gandas. the list of households of was obtained from each ganda administration. the sample size was determined by using the following formula (daniel, 1999): n = 𝑁𝑍2𝑃 (1 − 𝑃) 𝑑2 (𝑁 − 1) + 𝑍2𝑃 (1 − 𝑃) where n = sample size with finite population correction, n = population size, z = z statistic for a level of confidence (z = 1.96 at 95 % confidence), p = expected proportion (in proportion of one; if 20 %, p = 0.2), and d = precision (in proportion of one; if 5 %, d = 0.05). accordingly, 77 households were selected from wabo ganda from a total of 536 households, 90 households from gechi ganda from 629 households, and 45 households from hamuma ganda from a total of 314 households. 2.3. data analysis collected data were analyzed both quantitatively and qualitatively using descriptive statistics (percentage, frequency and mean) with microsoft excel. figure 1: map of yayo coffee forest biosphere reserve (source: unesco, 2013) etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 82 3. results and discussion 3.1. some socio-demographic characteristics of the respondents the socio-demographic characteristics of the households participated in the survey is shown in table 1. of the total respondents 80.7% (171) were males and 19.3% (41) were females. age of most of the respondents (64.6 %) was between 31 and 50 years. about 83 % of the respondents had attended formal education. it is believed that educated people are more concerned in conservation of natural resources than uneducated ones. previous studies have found that understanding factors influencing the perception of local people as it relates to forest values and attitudes toward protected areas is critical to the long-term sustainability of forests (graham et al., 2003). in addition, education, age and distance between a residence and a forest can significantly influence the perceptions of local residents as it relates to forest values and attitudes toward protected areas (mcfarlane and boxall, 2000). stoll-kleemann and welp (2008) identified many factors contributing to the success of biosphere reserves around the world. although the most influential factor was ‘environmental education’, several factors relate to public participation, collaboration with local authorities, community participation, leadership, political support at regional level and consideration of traditional knowledge, to mention some. the finding of this study is almost consistent with this idea: younger people and less educated people hold negative attitude toward the establishment and current management of the biosphere reserve. the respondents had one or more different sources of income and 92.5 % (196) of them mentioned that they obtained their income by collecting wild coffee berry from the forest while 81.1 % (172) were involved in crop production and only 39.2 % (8) were involved in livestock rearing. their sources of income were related to forest and combined with population increase; it is believed that they have impacts on the forest. by citing the official report of the former yayo-hurumu district rural and agricultural development office, zewdie jotte (2010) reported that crop, animal, and coffee production account for 51 percent, 14 percent and 30 percent of the total production in the district, respectively. the remaining 5 percent of the production is covered by khat growing and other agricultural production activities. table 1: socio-demographic characteristics of the respondents around yayo forest coffee biosphere reserve (n = 212) 3.2. community’s attitudes towards the establishment of yayo coffee forest biosphere reserve respondents’ attitudes towards the establishment of the biosphere reserve are shown in table 2. about 51 % (108) of the respondents had supportive attitude towards the establishment of the biosphere. about 86 % (94) of those who supported the establishment of the forest claimed that the biosphere reserve project would promote local development. contrarily, of those who showed unsupportive attitude towards the establishment of the biosphere, 49.5 % (51) and 52.4 % (54) claimed that they gained no benefit from the forest and lost their right on the forest, respectively. all the reasons they raised would put them in conflict with forest management bodies. variables frequency percent gender males females 171 41 80.7 19.3 age 21-30 years 31-40 years 41-50 years 51-60 years > 60 years 24 66 71 42 9 11.3 31.1 33.5 19.8 4.2 educational level no formal education 1-4 5-8 9-12 higher education 37 78 73 17 7 17.5 36.8 34.4 8.0 3.3 source of income crop production livestock raring wild coffee berry wild spices beekeeping others 172 8 196 15 54 10 81.1 39.2 92.5 7.1 25.8 4.7 etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 83 table 2: community’s perceptions towards the establishment of yayo forest coffee biosphere reserve (n = 212) 3.3 community’s perception about the values of the yayo coffee forest biosphere reserve the respondents were aware of the different values of the biosphere reserve. all (100 %) of them mentioned that the biosphere reserve was a home of wild coffee, a source of fuel wood (99.6 %), and a source of construction materials for the community (95.7 %) (table 3). this implies that combined with population growth, extensive forest clearing for cultivation, overgrazing, and exploitation of forests for fuel wood and construction materials, without replanting, obviously reduces forest cover. understanding the perception of local people as they relate to forest value is an important part of gaining a better understanding of major sources of conflict between those who want to emphasize community development and those in charge of nature management (xu and bengston, 1997). perception of forest values are a valuable sources of information on local perspectives, knowledge, and beliefs (silori, 2007). similarly buttoud (2000) suggested the way local people perceive the value of forests needs to be considered in the sustainable development of forests. in addition, mcfarlane and boxall (2000) also reported that a better understanding of how local people perceive the value of forests is fundamental to the development and implementation of sustainable forest management strategies. furthermore, changing perceptions of forest values over time can reflect the effects of forest management on local communities. consulting local communities, and understanding their views, therefore plays an important role in achieving public acceptance of protected areas, and ultimately in the conservation success. table 3: community’s perceptions of values of yayo forest coffee biosphere reserve (n = 212) forest values frequency percent home of wild coffee 212 100 fuel wood 211 99.6 construction 203 95.7 medicinal plants 129 60.9 pasture 119 56.0 beekeeping 132 62.1 ecotourism 49 23.2 3.4 community’s attitudes and perceptions towards forest protection and the management system of yayo coffee forest biosphere reserve community’s attitudes and perceptions towards protection and the management system of the forest are depicted in table 4. the respondents were aware of the existence of the nature reserve and 57.7 % (122) agreed that the community has a responsibility to protect the forest because of the forest values (especially, as a source of fuel and construction materials) the community gets from it. however, 60 % of the respondents mentioned that they were in disagreement to the implementation of restriction measures to forest resources to sustain the forest. in addition, 78.2 % did not agree on the conflict resolution management system because of the restrictions on the extraction of forest products and the punishment of those who break the devised rule. about 51 % (109) of the respondents mentioned that they were not satisfied with the management system of the forest mainly because of the restrictions on the extraction of forest products and the resulting punishment when they break the rule. dissatisfaction is the results of conflicts that exist question: do you support the establishment of yayo forest biosphere reserve? yes = 51.4 % (109) no = 48.6 % (81) reasons % (number) reasons % (number) a. solution for land ownership conflict b. promotion of local development c. generation of direct income d. participation of local people in the forest management e. promotion of the natural environment 37.6 (41) 86.2 (94) 30.3 (33) 33.0 (36) 64.2 (70) a. no benefit is gained from the forest b. loss of right over forest c. generate interest of conflict d. lack of awareness 49.5 (51) 52.4 (54) 25.2 (26) 14.0 (14) etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 84 between the local community and the managers of the biosphere reserve. the local people involved in illegal logging and forest clearing for farmland expansion, especially, for coffee farming. most (64 %) of the respondents mentioned that they were not satisfied with the forest management system because of low level of the involvement of the local people in the decision making process. local communities, at any cost, have to be consulted on decisions affecting their life and building appropriate channels that enable them to get benefits from the protected area. it also helps to get and maintain their positive attitude and relationship between protected area and the local community zewdie jote (2010). full implementation of the co-management system of the forest with local community will help in conflict resolution and forest conservation. co-management approaches are more effective than top down approaches (karanth and nepal, 2012). comanagement joins management and improvement of the livelihoods of the local people (ting et al., 2012). local people may support nature reserve management if their livelihoods are met (karanth and nepal, 2012). 3.5 threats of the biosphere reserve and conflicts between the community and the biosphere reserve management community perceptions about threats currently facing yayo coffee forest biosphere reserve are shown in table 5. although all the respondents were aware of that the forest was protected from settlement by the law, most of the respondents (71 %) mentioned that the forest was not free from agricultural encroachment. besides, all the respondents (100 %) were aware of the presence of large-scale development projects like yayo coal mining industry and yayo fertilizer factory which were legally established around the forest, gaba hydropower dam, road construction and electric transmission line established legally inside the forest, and coffee plantation carried out illegally inside and around the forest (27 %). these projects are planted some inside and some adjacent to the biosphere buffer zone and transition area. the emergence and implementation of large-scale development projects which accommodate a range of intensive land-uses have adverse effects on the biodiversity of the area if not properly managed. to some extent, depletion of natural resources such as land, forest, water, soil, etc. is inevitable. as a result of the project expansion to the buffer and core areas, its forest cover has been declining. particularly, the establishment of yayu fertilizer industry resulted in the establishment of smaller towns in the area. witate town could be an indication of its implication. the factory attracted many people (workers) with their large families to the area. it is assumed that the factory will create job opportunities for more than 30,000 workers. these workers are coming to the area with their accompanies. it is also expected that they intend to sustain their living depending on the natural resource of the area, which further implicate the loss of biodiversity (oefcca and ofwe, 2018). about 62 % of the respondents reported that they did not support investments carried out both in the vicinity and inside the forest as investments expel native residents from their places, benefit oriented rather than conservation, damage forests, lead to climate change, and impacts on wild animals. table 4. community’s attitudes and perceptions towards protection and management system of yayo coffee forest biosphere reserve statement agree disagree it is the responsibility of the local people to protect the forest 57.7 (122) 42.3 (90) restriction measure must be implemented to sustain the forest 40.0 (85) 60.0 (127) the forest management system solved the conflict over the forest 21.8 (46) 78.2 (166) participation of the local people in the decision making process 35.2 (74) 63.8 (135) further, the establishment of these factories was not initiated by the local communities and not in consultation with the local government. for instance, the zonal and woreda (woreda is a word in amharic language for ‘district') administrations were not aware of how yayo fertilizer factory and coal factory were etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 85 established in the area. as a principle, all develop¬ment projects, both private and government, should submit the environmental and social impact assessment report to the bureau/office of environment, forest and climate change authority and get approval prior to the project (oefcca and ofwe, 2018). about 49 % (103) of the respondents had unsupportive attitude towards the establishment of the biosphere reserve and the reasons they raised were related to their interest which could be considered as sources of conflicts. about 73 % (154) of the respondents mentioned that livestock graze in the forest. ninety-one percent (n = 193) of the respondents mentioned that there were conflicts between the management bodies of the biosphere reserve and the local community over the forest. the respondents mentioned different sources of conflict like timber logging (100 %), charcoal production (45.1 %), expansion of farmland (32.6 %), and gain of no benefits/incentives from the government (92.5 %). some respondents knew the major indigenous tree species logged from the forest by their local name and their use values. accordingly, 26 % and 23 % of them mentioned cordia africana (waddeessa, afan oromo) and aningeria adolfi-friederici (qararoo, afan oromo), respectively, were logged mainly for timber. whereas, 19 % and 15 % of the respondents reported that diospyros mespiliforms (qollatii, afan oromo) and diospyros abyssinica (lookoo, afan oromo), respectively, were logged for house construction and 17 % of them witnessed that acacia abyssinica (laaftoo, afan oromo), for charcoal production. there are formal institutions related with coffee forest management that operate at local and higher levels. the ministry of agriculture and rural development, institute of biodiversity conservation, woreda and kebele administrations, and oromiya government forest supervising agency are some of the formal organizations operating in coffee forest management or own potential relevance to the coffee forest management. kebele administrators mainly deal with the day to day activities of the rural residents. most of the rules devised at district and zonal levels are implemented at kebele level, but there are no rules as such that are devised at zonal and district level for the case of coffee forest. issues of natural resource management including coffee forest management are monitored at kebele level. violations of rules devised by many formal institutions, both government and nongovernmental organizations operating at local level, are followed at kebele level. the kebeles impose penalty on those who violate the rules. the coffee forest guards report to the kebele administration which has its own militias and social court to control any illegal acts like illegal logging and encroachments. kebele administrators and forest committee allow people to use few trees for timber from the buffer zone based on some arrangements (zewudie jote, 2010). zewudie jote (2010) reported that the need to expand coffee farm, disagreement on ownership right and community’s dependence on forest are the principal root causes leading to various forms of conflicts on the coffee forest. a preference of exploiting the economic values of the forest in this study suggests that the needs of local people for firewood, timber for construction, and expansion of coffee plantations are a source of conflict. regarding coffee plantations, coffee plants need less dense or moderate shade trees (beer et al., 1998). therefore, farmers cut dense shade trees for the effective cultivation of the coffee plants. in addition, cultivation of coffee needs cleaning of weeds that compete with. as a result, coffee plantations stay ground open and leads to local decrease in species diversity. western oromia, specifically the districts adjoining the coffee forest, are identified as coffee growing priority areas for which every effort is being made towards expansion of intensive coffee production. this only served to encourage deforestation or the replacement of coffee forests with few shade trees. these are the causes for conflict between the government that tries to conserve coffee forest biodiversity and the community that is eager to use coffee forest. it can also show the conflict between the government initiative to expand coffee farms/production and the need to conserve coffee forest biodiversity in the same area (zewdie, 2010). local community’s dependence on forest for livelihood and other uses mainly for construction materials is another source of conflict. due to the absence of alternative energy source in the area, people depend on sale of fuel wood. sale of timber is also a source of income, and people need forest products for agricultural tools. poverty or absence of alternative etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 86 means of subsistence also forces people to depend on coffee forest. this breeds conflict when government authorities attempt to restrict access to the forest. other sources of conflict in coffee forest management include the absence of community participation during demarcation, prohibition of access to forest and nontimber forest products, how to manage coffee forest, increasing coffee price, increasing population pressure, lack of grazing area, and confiscation of people’s land during demarcation (zewdie, 2010). population growth around the transition area of the biosphere reserve is another source of conflict. it is the major cause of deforestation and resulting increases in demand for wood products or forest land. for the rapidly growing populations, wood remains the primary fuel for cooking and heating. previous studies show that depletion of biodiversity is high in areas of poor people who need to benefit from various development endeavors to meet their livelihood demands. for example, food production in such areas must be intensified to meet the growth in demand due to rising expectations and the rapid increase of populations. yet agriculture, as traditionally practiced, has remained the major cause of destruction of valuable habitats, pushing species towards extinction (mcneely and scherr, 2001). the 2016 official report of the yayo district rural land administration and environmental protection office shows that the human population statistics around the transitional area of the biosphere reserve during the establishment of the biosphere reserve in 2010 was 13,693. after six years in 2016, the population increased to 22,961. population increase is one of the important factors in determining the rate of exploitation of the forest resources. the increasing population needs more cultivable land for livelihoods. this, undoubtedly, intensifies the conversion and/or modification processes of the land use types. they may be forced to encroach into forests for crop production, grazing, and settlement. solomon melaku (2016) noted that forest degradation in ethiopia is closely linked to the ongoing population growth. more people generally lead to an increasing demand on land for living and for agricultural production. consequently the pressure on the forest resources themselves increased due to a higher demand on fuel wood and construction timber. understanding the main source of conflict is critical to the resolution of conflict (yamsi et al., 2006). in addition, understanding the perceptions of the local people as they relate to forest value and attitudes toward the reserve is a key to gaining a better understanding the central issue of the conflict between community development and nature reserve management (xu et al., 2006). mitigating the conflict between biodiversity conservation and the rights to access forest resources, the twin tasks: conservation and economic development should be tackled simultaneously (castro and nielson, 2001; adams et al., 2004). the communities’ livelihood plays a key role for the sustainable conservation of the biosphere reserve. 3.6 community’s perceptions about trends in forest cover change and community’s participation in forest conservation about 71 % (150) of the respondents mentioned that they participated in forest protection activities and 73.7 % (156) of them mentioned that the forest cover declined because of population growth, expansion of farmland, and deforestation and about 65 % (137) of them agreed that the forest cover had been declining from time to time which has impacts on their livelihood (table 6). natural resource conservation could be secured from threat when local communities are perceived to manage and conserve their resources since they live with natural resources and they are primary users of natural resources (fao, 2010). in addition, it is already acknowledged that communities living within the vicinity of the protected areas are critical to the success of conservation efforts (robertson and lawes, 2005); such as the attitudes of local residents and the level of local perception as well as the conflicts between people and the protected areas have become a concern for protected areas effectiveness (alison et al., 2005). as stated by glasl (1999), successful conflict resolution relies on knowing how to address its triggers. the specific sources of conflict need to be recognized by conservation planners and policymakers. etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 87 table 5: threats to the biosphere reserve as perceived by the respondents no. questions percent of respondents (number) yes no don’t know 1 is the forest protected from settlement? 100.0 (212) 0 0 2 is the forest protected from agricultural encroachment? 29.2 (62) 70.7 (150) 0 3 are there any investment activities (projects) in and/or in the vicinity of the forest? 100.0 (212) 0 0 4 4 if your answer to the above question (3) is yes, types of investment: a. coal mining industry (around forest, legal) b. fertilizer industry (around forest, legal) c. gaba hydropower dam (inside forest, legal) d. road construction and electric transmission line projects (in and around forest, legal) e. coffee plantation (inside and around forest, illegal) 100.0 (212) 100.0 (212) 100.0 (212) 100.0 (212) 27.0 (57) 0 0 5 do you support the investment being carried in the forest or vicinity of the forest? 37.7 (80) 62.3 (132) 0 6 if your answer to the above question (5) is no, reasons: a. exclusion of local residents from native places b. investors are benefit oriented rather than conservation c. leads to decrease in both quantities and qualities of the forest d. leads to climate change e. leads to local migration of wild animals 77.3 (102) 59.1 (78) 34.1 (45) 17.4 (23) 10.6 (14) 7 do livestock graze in the forest? 72.5 (154) 15.7 (33) 11.8 (25) 8 is there any conflict between the management institutions and the local community over the forest? 91.0 (193) 0 8.9 (19) 9 if your answer to the above question (8) is yes, sources of the conflict: a. timber logging b. charcoal production c. expansion of agricultural land (e.g. coffee plantation) 100.0 (212) 45.1 (87) 32.6 (63) 10 do local people in the vicinity of the forest get benefits/incentives from the government so that they feel ownership of the forest and take responsibility in conserving the forest? 0 92.5 (196) 7.5 (16) table 6. perceptions of the local community towards forest resources conservation and management no. statements percent of respondents (number) 1 in what part are you participating in forest resources conservation and management? nursery management tree planting activities forest protection activities 6.6 (14) 22.6 (48) 70.8 (150) 2 in your view, how has the size of the forest cover changed over the past seven years? increased decreased i can’t decide 26.3 (56) 73.7 (156) 0 3 reasons for decrease in size of forest cover a. population growth b. expansion of farmland c. deforestation 70.8 (150) 67.1(142) 69.9 (148) 4 is the livelihood of the community affected by the forest decline? yes 64.8 (137) no 35.2 (75) i can’t decide etana tadesse & daniel getahun ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 88 4. conclusion and recommendations the study revealed that some of the respondents had unsupportive attitude towards the establishment of the biosphere lost their right on the forest and thus they were in conflict with the managing bodies of the forest. they acknowledged that the biosphere reserve was a home of wild coffee and a source of fuel wood and construction materials. combined with population growth, extensive forest clearing for cultivation, over-grazing, and exploitation of forests for fuel wood and construction materials, logging, without replanting, obviously reduces forest cover and would lead to loss of the wild coffee and its biodiversity. large-scale investment projects built without environmental impact assessments in and around the biosphere reserve are threats to the biosphere reserve. identifying problems related to protected area management enhances conservation of nature reserve. in problem solving process, active involvement of the local community in the management of the biosphere reserve, creating common understanding on the use and conservation of the biosphere reserve, and facilitating conditions to promote the livelihood of the community could manage the illegal extraction of nature reserve resources. in general, study pointed out that the local people’s need, perception, and attitude contain useful information that could be incorporated into the decisionmaking process regarding the use and conservation of the biosphere reserve. concerning participation in forest resources conservation and management, creating common awareness on activities such as result-based nursery (seedling) management and tree planting could resolve depletion of the forest. furthermore, creating common understanding of the community on ecological and social values of the forest could play a key role in sustainable conservation of the biosphere reserve. conflict management is an approach that can address the roots of conflicts by building upon shared interests and finding points of agreement that accommodate the respective needs of the various parties involved. in conflict management approaches: active involvement of the community in the management of the biosphere reserve, facilitating conditions to promote the livelihood of the community living in the biosphere reserve area could manage the illegal extraction of nature reserve resources, and creating common awareness and/or understanding on the use and conservation of the biosphere reserve. successful co-management depends strongly on the relationship between local people and protected area managers. local people, especially those living in and around protected areas, have important and longstanding relationships with these areas. their needs, perceptions, and attitudes contain useful information that could be incorporated into the decision-making process. considering their knowledge and opinions can lead to the resolution of conflicts and make management systems more effective and more favorable in practice. access to forest benefits can positively influence the perceptions and attitudes of local people. furthermore, local poor farmers are more concerned with immediate economic benefits than with preserving long-term forest health. therefore, if local people recognize that the benefits are too small or unevenly distributed, conservation approaches may fail 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(2006). stakeholder conflicts and forest decentralization policies in west kalimantan: their dynamics and implications for future forest management. for. tree livelihoods. 16, 167-180. zef and earo (2002). conservation and use of the wild coffee population of coffea arabica in the montane rainforests of ethiopia. project proposal for biosphere research integrative and application oriented mode projects – bio team, bonn. zewdie jote (2010). institutions, incentives and conflict in coffee forest use and conservation: the case of yayo forest in iluu abba bora zone, southwest ethiopia inaugural – dissertation 214pp. 68 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (1), 2019 journal home page: www.ejssd.astu.edu.et astu research paper association of coffee bean defects with ochratoxin a contamination in the samples originated from jima woreda of oromia regional state, ethiopia teshome geremew biru1,*, dawit abate tassew2 1department of applied biology, school of applied natural science, adama science and technology university, adama, ethiopia 2department of microbial cellular and molecular biology, faculty of science, addis ababa university, addis ababa, ethiopia * corresponding author, e-mail: teshome.geremew@astu.edu.et abstract filamentous fungi like aspergillus, penicillium, and fusarium are the common microbial contaminants in many agricultural products including coffee beans. these fungal species can produce mycotoxins in coffee beans and exposes consumers to mycotoxin associated health risks. the purpose of this study was to examine the various types of coffee bean defects existed in coffee beans in relation to ota contamination and search possible physical indicator to identify beans with ota contamination. seventy four coffee bean samples were evaluated visually for the presence of defective beans and the defects were counted and scored. the samples were also assessed for fungal incidence and ota contamination levels. fungal isolates were identified using species specific primers and rdna sequencing using its1 and its4. ota was analyzed using enzyme linked immunesorbent assay kit. the results showed significant positive correlation (r = 0.56, p < 0.00) between coffee bean defect points and ota contamination levels. the predominant coffee bean defects encountered in this study in descending order were black beans (41.6 %), immature bean (27.0 %), insect infested (20.5 %), moldy beans (20.4.4 %), and broken beans (15.5%). aspergillus ochraceus and aspergillus westerdijikiae were found to be the predominant ochatoxigenic species encountered in the coffee beans. ochratoxin a contamination levels in coffee beans were positively correlated with black beans (r = 0.33, p < 0.03), visible mold overgrowth (r = 0.80, p < 0.00), beans damaged by insects (r = 0.71, p < 0.00), and presence of husk (r = 0.67, p < 0.00). visual inspection of the incidence of these bean defects is a potential indication of ota contamination in the beans. therefore, local coffee consumers should avoid coffee beans with sign of mold overgrowth, black beans, beans with husk and damaged by insects as these types of coffee beans are most likely contaminated with ota and causes health risk. keywords: black beans, defect count, mold, ochratoxin 1. introduction coffee consumption in the world was estimated to about 152.1 million bags (60 kg) in 2015 with an average global demand increased by2% (ico, 2016). coffee is produced by more than 60 developing countries and the earnings from coffee exports are of vital importance to these countries. coffee is an important means of social development and a great source of rural employment, providing a livelihood for some 100 million people around the world (nicolas, 2007; gray et al., 2013). most of the coffee consumed by the local people in ethiopia is lower quality since some of the beans have been originally destined for export but often rejected from export. interestingly, even though it may be a lower quality than what is exported, the price of coffee in the local marketplace is sometimes higher than the international price. this high price of substandard http://www.ejssd.astu.edu/ mailto:teshome.geremew@astu.edu.et teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 69 coffee on the local market has pushed some consumers, particularly those with low purchasing power to utilize even poorer quality beans with very high defects that are characterized by mix of black, sour, broken, discolored, insect damage, moldy, husk, cherry, soil, stick, stone, off odor, wanza (seed of cordia africana) and others. in worst case this segment of the local community was even forced to make coffee beverage from the husk (skin) of coffee cherry as an alternative to coffee beans (abu, 2015) coffee bean defects are described as foreign materials of non-coffee (e.g., stones/sticks) and nonbean origin (e.g., husks/hulls), abnormal beans regarding shape and visual appearance, such as black beans or any defect that impairs brewed coffee taste and flavor (leroy et al., 2006). coffee bean defects can be divided into primary and secondary defects. black beans and sour beans are usually identified as primary coffee bean defects. secondary defects principally include broken beans, insect-damaged, faded, green, moldy and silver skinned beans. bee et al. (2005) and agresti et al. (2008) have demonstrated that coffee cup quality is strongly compromised by bean defects since they reduce significantly the characteristic quality of coffee beverage. by and large, several kinds of coffee bean defects are encountered in locally sold coffee beans compared to the export portion in coffee growing countries like ethiopia and brazil (mendonca et al., 2008). insect infestation of coffee beans can severely reduce both the physical and organoleptic quality of the beans. moreover, insects have been shown to serve as vectors for a wide array of fungi. in some cases, insect disseminated fungi produce potent toxins in the host plant, which might create sever problems to this agribusiness (kulandaivelu et al., 2010). studies indicate that the coffee berry borer (cbb), hypothenemus hampei (ferrari) (coleoptera: scolytidae) could disseminate toxigenic fungi in coffee plantations (kulandaivelu et al., 2010). once the fungi get their way through the cherry, the spores can remain within the holes created by the insect on the beans after harvest and processing. inappropriate drying and poor storage conditions aid the spores to germinate and increase mycotoxin concentration in the beans (yan-xuan et al., 2015). beside insect damage, extrinsic coffee bean defects including presence of soil, stone, stick, and husk can serve as means for soil fungi to get into the beans. based on this background information we hypothesize that coffee beans with higher defect points may contain higher fungal incidence and ota contamination compared to coffee beans with standard quality. there might be also coffee bean defects that can be used as indicator for ota contamination in the beans and these defects may serve as possible visual/physical marker for screening ota contaminated coffee beans during coffee purchase in the local markets. in line with the hypothesis the study aims to evaluate potential physical/visual methods to discriminate ota contaminated coffee beans that can easily be used by the coffee consumers during raw coffee bean purchase. 2. materials and methods 2.1. coffee samples coffea arabica samples (74) of one kilogram each were collected based on incremental sampling method from farmers’ households, market places and mill stores from six woredas in jimma zone of oromia regional state from 2014-2015. the samples comprised coffee from different processing methods, varied storage conditions, and having different packaging material. moisture contents of the coffee samples were recorded at the site of collection using an electronic moisture tester (hoh-express-he-50, germany). the samples were packed in plastic bags, properly labeled, and stored at 4oc for further study. 2.2. coffee bean defect count coffee defect counts were conducted by using the manuals ethiopian ministry of agriculture and rural development coffee and tea quality control and liquoring center developed in 2009 (abrar and negussie, 2015). from every sample 100 grams coffee beans were taken for defect count. all types of bean defects were counted and defect points were assigned based on their occurrence. if a coffee bean sample has more than one defect, the highest defect is counted. portion of beans judged as defective were weighed and the weights were converted in to percentage. 2.3. isolation of fungi and infection prevalence from each sample, beans were randomly selected and surface sterilized by treating with 1.3% sodium teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 70 hypochlorite for 2 minutes. beans were rinsed three times with sterile distilled water. malt extract agar medium amended with 0.01% chloramphenicol was used for plating experiments to avoid bacterial outgrowth. five surface sterilized beans were aseptically placed on a petri dish and incubated upright at 25°c for 10 days. every microbial colony that appeared on the beans were counted as black aspergilli, yellow aspergilli, penicillium spp., fusarium spp., and others. fungal colonies were picked up with a sterile needle and purified by transferring to czapek’s dox agar medium. pure isolates were preserved on czapek’s dox agar slants in the refrigerator at 4°c for further study. the frequency of isolation of fungal genera and group and total microbial load were computed based on the following formula. frequency (%) = 𝑁𝐵𝐺 𝑇𝑁 𝑋 100 percent of fungal infection (%) = 𝑁𝐵𝐹 𝑇𝑁 𝑋 100 where nbg represent number of beans from which the genus isolated, nbf is number of beans from which a fungus isolated and tn is total number of beans analyze. 2.4. fungal isolation, morphological and cultural examination isolates were visually analyzed based on colony growth rates, texture, degree of sporulation, color of mycelia, shape of conidial heads, vesicles, the number of branching points between vesicle and phialides (i.e. uniseriate or biseriate), phialides and conidia were observed for the primary screening of isolates to genus level according to naviet al. (1999). representative isolates were maintained in czapek’sdox agar slant and 10% glyceron in addis ababa university and bccm (belgian co-ordinated collections of microorganisms), belgium respectively. 2.5. taxonomic identification of fungal isolates representative isolates from the genus asperillus, penicilliu, and fusarium were selected for molecular study and mycotoxin analysis. fungal dna was extracted from 100 mg of freeze-dried mycelium using cetyl-trimethyl-ammonium bromide (ctab) protocol as described by stewart and via (1993) with some modification. spores from five day old cultures were inoculated in to yeast extract sucrose (yes) broth medium on 2ml plastic wells and grown for five days. the mycelia were separated from the broth and transferred to 2 ml epindrhof tubes and maintained at 80oc for one hour. after one hour, the mycelia were freeze dried for an overnight in frieze dryer. the following day the mycelia were pulverized in eppendorf tubes using micro pestle. to about 50 mg pulverized mycelia, 500 µl solution containing 1:3(m/v) protinase k in ctab buffer (2% cetyltrimethylammonium bromide, 1% polyvinyl pyrrolidone,100 mmtris-hcl, 1.4 m nacl, 20 mm edta) was added and vortexed for 30s in a vortex mixer. then, it was incubated at 65oc for 30 min in a water bath. after incubation the dna was rested on ice for 15 min. to the cooled nda 500 µl chloroform isoamyl alcohol (24:1) was added and mixed by rotating the tubes by hand and centrifuged at 13200 rpm for 10 min. the tubes were removed from the centrifuge and 300 µl upper aqueous phases was taken to new tubes. an equal volume (300 µl) of isopropanol was added and mixed gently. then it was centrifuged at 13200 rpm for 10 min. the supernatant was discarded with micropipette and the pellet was washed with 400 ml of 70% ethanol by centrifugation at 13200 rpm for 1 minute (to remove the isopropanol). after centrifugation, the supernatant was discarded and the pellet was left to dry in the tubes for 15 min in fume hood. after drying, the dna was resuspended in 50 µl tris edta and maintained at -20oc. dna concentrations of all samples were determined using quantusfluorometery, promega usa according to the machines user manual. different concentrations ranges were taken and tested for suitability of pcr. master mix consisting of 14.5µl h2o (sigma), buffer 5µl, dntps 1.25µl, primers 1µl each (its11 and its4) and taq polymerase 0.125 µl was prepared per samples. the master mix (22.85µl) was dispensed in reaction plates and 2µl templet dna from each sample was added to respective reaction plates. the reaction plates were sealed by a parafilm and all the above procedures were done on ice. pcr products were subjected to gel electrophoresis on 1.5% agarose gel with 1-2µl of loading dye (6x) at 120v for 45 minutes with dna mass ruler (thermo scientific gene ruler, 100 bp dna ladder). at the end of 45 minutes the gel was submerged in ethidium bromide (0.5µg/ml) for 30 minutes. dna bands on the gel were captured using gel teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 71 0.0 10.0 20.0 30.0 40.0 50.0 % a g e d e fe c t p o in ts defect types doc xr+ system integrated with image labtm (biorad molecular imag gel decxr, usa). 2.6. fungal dna purification for sequencing fungal dna was extracted as described before and amplified using its1 and its4 primers. pcr thermal protocol was as follows: initial 5 min denaturation at 95°c, 32 amplification cycles at 95°c for 30 s, 55°c for 30 s, 72°c for 60 s, and a final extension step of 72°c for 10 min in a total volume of 50 µl reaction mix and 2µl temple dna. pcr products of 5µl were loaded to 1.5% agarose gel with 2µl of 6x dna loading dye (life technologies) and with 100 bp dna mass ruler (thermo scientific) to assess suitability for sequencing. the gel was ran for 45 minutes at 120v and socked in ethidium bromide tank (0.5 µg/ml) for 30 minutes. images of dna bands were captured using bio rad molecular image gel dec xr+ (usa) with image lab version 5.0 build 18 software. the samples were purified with the help of e.z.n.a. cycle pure kit, omega bio tek based on the manual provided by the manufacturer. after cold storage for an hour at -800c the dna samples were freeze dried for an overnight and sent to sequencing company (macrogen, korea). pcr reactions were performed in geneampr pcr system 9700 (applied biosystem, singapore). 2.7. identification of aspergillus isolates using species specific primers aspergillus isolateswere identifiedusing the primer pairs specific to each species. the pcr conditions for a. ochraceus and a. westerdijkiae were according to gil-semaet al, (2009). for a. ochraceus, the pcr cycle comprised 5 min at 95°c, 35 cycles for 30s at 95°c, 30s at 62°c, 40s at 72°c and finally 3 min at 72°c. for a. westerdijkiae it was 5 min at 95°c, 30 cycles for 30 s at 95°c, 30s at 63°c, 40s at 72°c and finally 5 min at 72°c. amplification conditions for a. niger was 95°c for 5 min, 35 cycles at 95°c for 30s, 62 to 72°c gradient for 30s, 72°c for 30s and 72°c for 5 min in biorad t100 thermal cycler 2013, singapore. pcr products were ran on agarose gel and visualized as described before. 2.8. ochratoxina (ota) analysis for ota analysis one hundred grams of coffee samples were ground till 50% pass through a 20 mesh screen (0.85 mm) and 10 grams were sub sampled for ota analysis. the samples (10 gram) were extracted with 80% acetonitrile in distilled water for 5 minutes on a rotary shaker at 150 rpm. the supernatant was filtered with whatman no.1 filter paper and the clarified extracts were dilute to 10:1 with 70 % methanol in distilled water. ota analysis was conducted as described in the manual of sigma aldrich ota elisa kit (ref.) for coffee and all the analyses were done in triplicate. 2.8. data analysis for correlation analysis r software version 3.0.3 was used. spearman's rank correlation was used to examine the association of total bean defect points with ota concentration levels. kruskal-wallis rank sum test was used to evaluate significance differences among the independent variables in relation to the predictor (bean defect point). multiple comparison tests after kruskalwallis (kruskalmc) was used to see observed values above critical at 0.05 levels. gen studio professional edition was used to process the molecular data before standard nucleotide blast (https://blast.ncbi.nlm.nih.gov). 3. results and discussion 3.1. results the result of coffee bean defect count for all samples indicated that 13 types of defects were encountered and all the samples contained defects (figure 1). the predominant coffee bean defects encountered in this study in descending order were black beans (41.6 %), immature bean (27.0%), insect damaged (20.5%), moldy beans (20.4%), broken beans (15.5%), husk (11.4%) sour beans (7.3%), and cherry (5.9 %)(figure 1). figure 1: bean defect types encountered in coffee samples. error bars are based on 95% confidence interval. https://blast.ncbi.nlm.nih.gov/ teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 72 correlation analysis of coffee bean defect point and ota concentration in coffee bean samples indicated significant correlation between bean defect point and ota concentration (r = 0.56, p < 0.00). ota contamination levels in coffee beans were significantly correlated with black beans (r = 0.33, p < 0.03), visible mold (r = 0.80, p < 0.00), insect damaged beans (r = 0.71, p < 0.00), and husk (r = 0.67, p < 0.00). however, no significance correlations were observed between coffee beans ota concentration levels and beans with defects including sour (r = 0.16, p < 0.29), presence of cherries (r = 0.15, p < 0.32), sticks (r = 0.00, p < 0.97), soils (r = 0.04, p < 0.81), stones (r = 0.08, p < 0.61), immature beans (r = 0.08, p < 0.59), wanza seed (r = 0.09, p < 0.55), broken beans (r = 0.01, p <0.95) and with off odor beans (r = 0.13, p < 0.38). 3.1.1. fungal isolation, morphological and cultural characteristics more than 500 isolates were obtained from the coffee bean samples and 87% of the coffee samples were contaminated with various fungal species (figure 2). most frequently encountered fungal species belonged to the genus aspergillus (79%), fusarium (8%) and penicillium (5%). the remaining 8% belonged to the genera trichoderma and rhizopusspp. figure 2: fungal contamination on coffee samples. representative toxigenic fungal pure cultures of a. westerdijkiae, aochraceusea. steynii, and a. flavus were indicated in figures 3 and 4. figure 3: pure cultures of a. westerdijkiae (a = obverse side, b = reverse side) and a. ochraceus (c = obverse side, d = reverse side) isolated from coffee beans figure 4: pure cultres of. a. steynii (a = obverse side, b = reverse side) and a. flavus (c = obverse side d = reverse side) isolated form coffee beans table 1 shows the sources of coffee bean samples and median values of bean defect, fungal incidence and ota contamination levels. no significant difference in median bean defect point were observed among the samples collected from different sources (p > 0.23). however, percentage of bean defect point was highest for samples obtained from addis ababa (20.40%), followed by mana (18.04%), seka (17.54%) and shebbe (12.99%). the lowest percentage of bean defect was teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 73 observed for samples obtained from jimma town (4.12%) table 1. statistically, no significant difference existed in median coffee bean defect point (x^2= 2.78, p < 0.43) with in the processing types. however, median bean defect point obtained for dc coffee samples was highest (94.70), followed by dt (83.80) and wp (69.60) figure 5. table 1. coffee bean defect points, fungal incidence and ota contamination levels on coffee samples nb: n represent number of samples from a specific district. figure 5: coffee bean defect points in relation to processing type (dc = samples dried on concrete dsg = samples dried on soil ground, dt = samples dried by traditional methods like on animal skin, clothes etc., wp < wet processed sample. box = inter quartile range, bold lines = median values, lower and upper hinges = lower and higher values, circles = outliers). figure 6: coffee bean defect points in relation to storage types (box = inter quartile range, bold lines = median values, lower and upper hinges = lower and higher values). significance difference in median bean defect was also observed among the different storage types (p < 0.00). median coffee bean defect point (93) for beans stored in mill store was highest followed by residence (69) and least (56) for bean samples obtained from shop (figure 6). no significance difference exists between bean defect points and duration and storage material. there was no correlation between bean defect points and fungal incidences (r = 0.23, p < 0.06). 3.1.2. molecular identification of the fungal species pcr assay using two pairs of species specific primers (ochraf, ochrar, westf and westr) enabled the identification of 23 aspergillus ochraceus and 13 aspergillus westerdijikiae species (figure 7 and 8). dna sequence analysis using its1-its4 primers revealed the identity of 25 isolates (2 a. flavus, 2 a. niger, 1 a. funigatus, 1 a. melleus, 5 a. westerdijkiae, 6 a. ochraceus 2 a. steynii, 1 a. tubigenesis, 1 g. moniliformis, 1 g. zea, 2 p. brevicompactum and 1 p. verruculosum). the results of molecular identification indicatedthe majority of fungal isolates belong to the genus aspergillus. sample source median beans defect points (%) median fungal incidence (%) median ota level (µg/kg) dedo (n = 10) 11.16 100 1.77 gomma (n = 10) 6.90 48 0.12 shebbe (n = 10) 12.99 96 1.07 seka (n = 10) 17.54 100 1.18 limmu (n= 7) 8.82 96 0.42 mana (n = 11) 18.04 92 2.21 jimma town (n = 5) 4.12 76 0.87 adds ababa (n= 11) 20.40 80 2.21 teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 74 figure 6: pcr assay with primers ochra1 and ochra2 specific to a. ochraceus n.b.: lane m: 1000 pbgeneruler, lanes 1-38 samples dna. lanes 1, 3-5, 8, 11-15, 19, 22-26, 28-37 indicates dna of 400 bp identified as a. ochraceus. figure 7: pcr assay with primers westf and westr specific to a. westerdijkiae n.b.: lane m: dna molecular size marker, lanes 1-56 samples dna. lanes no. 1, 3, 4, 5, 13, 15, 20, 29, 39, 40, 47, 49 and 54 indicate dna of 450 pb, identified as a. westerdijkiae teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 75 3.2. discussion the purpose of this study was to search for possible visual screening method of coffee beans contaminated with ota based on physical defects so that the local community can easily avoid ota contaminated beans using the physical appearance of the beans. coffee beans delivered to local market and consumed by the local community were examined for bean defect levels, bean defect types, fungal incidence and ota contamination level. the results of the investigation revealed that the average bean defect level was as high as 219 (11 %) in the locally consumed coffee in relation to 86 defects (4%) maximum allowed defect level (scaa, 2015). thirteen types of defects were observed in the samples of which four types of defects (black beans, immature beans, insect damaged beans, moldy beans, broken beans and beans mixed with husk) showed significant association with of ota contamination levels. these defects were identified as the major contributors to higher ota level in the locally consumed coffee beans. this finding is in line with the study of taniwaki, et al. (2014) who have investigated that ochratoxigenic fungi and ota in defective coffee beans and found out the sour and black defective beans had the highest ota concentration. similarly, the occurrences of black beans in higher percentage coincide with the finding of toci and farah (2008) who have revealed the presence of considerable proportion of black and sour beans in brazilian arabica coffee. several studies (franca et al., 2005; pamela et al., 2008) elucidated the difference between defective and nondefective beans in terms of physical and chemical attributes including ota contamination levels. in search for physical means of discrimination between defective and non-defective beans, abebe et al. (2014) have reported the presence of higher coffee bean defects in ethiopian coffee samples that originated from sidamo (58% defective) and lower for samples obtained from harar (24.86% defective). there were two major reasons for the higher proportion of defective beans in the locally sold coffee and portion consumed by the producing farmers. one of the major reasons, as evidently observed during sample collection, was the sorting of sound beans for international market and defective beans for local market. sound beans were appropriately dried, sorted manually, packed in sisal sacks, and supplied to ecx (ethiopian commodity exchange) for grading. based on physical defect count and sensorial (organoleptic) analysis grades were given to the beans by trained panel of expertise. coffee beans failed to satisfy the export standard quality were redirected to the local market. defective beans removed from quality beans by manual picking were also pooled and mixed with some sound beans and supplied to local markets for the local community. this phenomenon is practiced in the developing countries in the world including the world’s top coffee producing country brazil (franca et al., 2005). secondly, coffee farmers harvest sound red cherries on time and supply to coffee processing firms. alternatively they can also dry the cherries and supply sound dried cherries to coffee mill houses whose target were foreign market. any inappropriately harvested, poorly dried, deteriorated cherries collected from soil ground ended up in the nearby open local market at a relatively cheaper price. even more deteriorated cherries that could not be sold at the local market can be consumed by the families of the producing farmers implying the risk of ota to the producing farmers. as explained above, both the coffee processing industries and the coffee farmers contribute to the supply of low quality defective beans to the local market. unlike cereal grains which can alternatively be used as animal feed, there is no any other option to utilize coffee beans other than beverage making in ethiopia. as a result, both defective beans rejected by exporters and deteriorated portion supplied to the local market by the producing farmers synergistically contributed to the higher percentage of defects in the locally available coffee. this leads to health risks of local coffee consumers due to consumption of ota. the relatively lower price of highly defective beans attract very poor portion of the community as this group of community cannot afford to pay for good quality beans at a higher price. this indicates the vulnerability of the poor population group to ota associated risks in connection with coffee consumption. detail explanation of the root causes of all bean defects encountered in this study is beyond the scope of this study. however, in search for the variables accounted for each defect types various processing types, storage types and storage material were evaluated. the statistical analysis of the data did not teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 76 support our previous assumption that processing types, storage types and storage materials might have effect on bean defect points. as previously explained by oliveira et al. (2008) and taniwaki et al. (2014) bean defects like immature beans, black beans, and sour beans can originate from coffee plantation field related to inappropriate harvesting, and poor processing practices. therefore, a comprehensive study of coffee processing from field to cup is needed to appropriately point out the root causes of all type of bean defects. several authors explained the effect of poor pre and post-harvest practices on the quality of coffee and ota contamination (toci and farah, 2008; batistaet al., 2009; birhanet al., 2014).the findings of these authors indicated that bean defects are the result of poor agricultural practices and poor post-harvest handling practices. these poor agricultural practices include inappropriate processing and post-harvest handling practices with wrong storage materials and rooms that contribute to the elevated bean defects and ota contamination levels. one of the entrusting finding in this study was the statistically significant association of bean defects including black beans, immature beans, insect damaged beans, moldy beans, broken beans and beans mixed with husk with high ota contamination level. this finding pointed out the order of significance of these defects to ota contamination and can be potential indicator of toxin presence in the coffee samples. the result of ota analysis indicated the highest toxin level in cherry samples with visible mold overgrowth. as previously hypothesized in this study, visual observation of mold overgrowth on coffee samples implicated with the highest ota content. this finding is substantiated visually by observable mold overgrowth on coffee samples that can be used as primary evidence for possible ota contamination in the local market. since these kinds of coffee are relatively cheaper in price, they attract the poorest communities in the market and this community makes coffee beverage by using both the beans and husk of the cherry. on a previously published paper by abu and teddy (2013), the use of coffee husk for coffee beverage making was reported due to the higher price of beans in non-coffee growing areas. the husk of the cherry which is the external cover of the beans is more exposed to fungal and insect attack. local people who make beverage of coffee by including the husk are at the highest risk of exposure to ota. during sample collection for this study it has been observed that the local people were selling and buying the husk. the presence of ota in coffee husk at a higher proportion was already explained (taniwaki et al., 2014). the strong positive correlation of ota with insect infested beans is another potential indicator of ota contamination. insects associated with coffee cherries are known to disseminate toxigenic fungi (vega et al., 2006) among the cherries and indication of insect puncture on the bean could be one condition for ota contamination. this finding substantiated the possibility of insect infestation as one clue for ota contamination. the other potential clue identified in this study for ota contamination was the presence of husk or the incomplete removal of the husk from the beans. positive correlation of ota with husk containing beans implies one of the potential sources of ota can be the husk. the study of viani (2002) indicated that coffee husks were significant source of ota contamination and cleaning of green coffee effectively reduced ota levels in coffee beans. the black beans were also found to be associated with ota in this study. in line with this finding, taniwaki et al. (2014) have revealed the association of ota with black and sour defective beans in samples obtained from two coffee growing regions of brazil. during the sample collection it has been observed that fully black beans were sold at half the price of sound beans (54ethiopian birr nearly 2 usd per kg) in addis ababa. people purchase these kinds of black beans and according to the sellers these black beans provide bitter taste to coffee beverages and some proportions of the black beans are mixed with quality beans. the commercialization and adulteration of defective beans with sound beans was reported from brazil (taniwaki, et al., 2014). however, the supply of defective beans like black, insect damaged, moldy and husk were not reported from ethiopia. the act of commercializing black defective beans for beverages making in ethiopian local market apparently contributes to ota related health risks. this kind of act should be discouraged by setting mycotoxin regulation on the locally sold coffee in order to protect public health. at the same time an alternative way of utilizing the bulk of defective coffee beans that can be removed from export beans should be teshome geremew & dawit abate ethiop.j.sci.sustain.dev., vol. 6 (1), 2019 77 explored out instead of damping in the local market for human consumption. very few reports (barragan and rodriguez, 2010) are available on the alternatives use of defective coffee beans as a medium for the growth of pesticide degrading bacteria. in ethiopia, local people usually wash the beans or cherry to removes impurities and the off odor from beans before roasting to make coffee beverage. however, washing and roasting cannot remove the toxin and the only option is to avoid beans with an indication of mold overgrowth, insect damage, contains husk and having off odor to scent as these type of beans are associated with the toxin. the overall fungal contamination obtained in this study (87 %) was nearly similar to results by fikreet al. (2015) (80%) and el aarajet al. (2015) (87 %) who evaluated fungal incidence from coffee samples obtained from limmu (ethiopia) and from morocco respectively. however, 100 % incidence was reported by urbanoet al. (2001) on robusta coffee samples by the direct plating technique. these findings indicated the poor postharvest handling practices common in developing countries including ethiopia and it is an area where intervention is needed. molecular identification convincingly revealed the presence of various toxigenic fungal isolates associated with coffee samples. since complete avoidance of toxigenic fungi from agricultural commodity is unavoidable reduction of contamination is possible by implementing good agricultural practices. the detection of ota in coffee samples substantiates the toxigenic potential of the isolates. however, detail molecular analysis of the fungal isolate was beyond the scope of this paper. 4. conclusion and recommendation this study attempted to search for potential method used by the local community in discriminating ota contaminated coffee at local market. the result of the study revealed the presence of higher percentage of defective beans in coffee portion supplied to the local market in ethiopia. the reasons for this higher proportion of defective beans in the locally sold coffee were the supply of off grade coffee failed to pass to international market, mixing of manually sorted defective beans to sound beans, and the preference of farmers to sell good quality coffee to mill stores for export and poor quality to local market. presences of higher percentage of defective beans including immature beans, insect damaged beans, moldy beans, beans with husk, and black beans were significantly associated with ota contamination. these types of coffee bean defects can be used as indicators for possible ota contamination. since defective beans were found to be the potential sources for ota, coffee processing firms and coffee farmers should avoid mixing defective beans with sound beans to supply to the local market. the defective beans should be rejected as they are hazardous to the health of the consumers. researchers should explore for an alternative way of utilizing defective coffee beans that are unfit for human consumption. the local community should make visual and olfactory assessment on the coffee beans and ascertain that the beans should not contains mold overgrowth, infested with insects, mix of husk, musty smell, black beans and mixed cherries. ethiopian coffee farmers should avoid the drying of cherries on soil ground and picking of cherries fallen on the soil ground for extended period of time in order to avoid or minimize mold colonization. above ground drying beds and the use sisal sack for storing the cherries are highly recommended. reference abebe, b., yirgalem, b., ataklti, a., dagne, c. and hyung, k. 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(2002). effect of processing on ota content of coffee. advances in experimental medicine and biology, 504, 189-93. yan-xuan, z., li, s., gong-you, lin, jian-zhen, l., xia, ch., jie, j., zhi-qiang, zhang, yutaka, s. (2015). novel use of predatory mites for dissemination of fungal pathogen for insect biocontrol: the case of amblyseiusswirskii and neoseiuluscucumeris (phytoseiidae) as vectors of beauveriabassiana against diaphorinacitri (psyllidae). systematic and applied acarology, 20(2), 177–187 61 © 2023 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 10 (1), 2023 journal home page: www.ejssd.astu.edu.et astu research paper determinants of rural-urban migrants’ employment choices in the urban labor market: a study from selected cities in central oromia, ethiopia. oumer berisso1 and habtamu kebu2 1department of economics, school of humanities and social sciences, adama science and technology university, p.o.box:1888, adama, ethiopia. 2department of psychology, school of humanities and social sciences, adama science and technology university, p.o.box:1888, adama, ethiopia article info abstract article history: received 07 august 2022 received in revised form 18 december 2022 accepted 23 january 2023 this study investigates the determinants of rural-urban migrants’ employment choices in the urban labor market in central oromia cities, ethiopia. the study used a cross-sectional data obtained from rural-to-urban youth migrants, and it estimated multinomial logistic regression to analyze the data. for this purpose, after the urban labor market had been categorized into five urban employment segments, a multinomial logit model was employed to identify factors determining migrants’ job choices from these employment segments. the finding reveals that a migrant’s sex and his/her parent’s annual income have positive significant effects on all employment segments. migrant’s marriage, information deficiency on job availability, being from small urban area, and father’s occupation have significant positive effects on selfemployment, while lack of a city’s identification card for the immigrant and dispute in the city have significant negative effects on the segment. migrant’s duration of living in cities, information deficiency on job availability, and father’s education and occupation have significant positive effects on informal private-employment. on the contrary, marriage, household size, and lack of identification card have negative impacts on the segment. a migrant’s age, preparatory schooling level, university education, access to registration, and advisory services in the city have significant positive effects on both (private and public) formal employments. the paper has made conclusions and drawn policy implications for possible interventions to urban labor market constraints. keywords: urban labor market, rural-to-urban migrant, employment segments. jel classification: e24; e26; j21; j24; j45. 1. introduction migration as a human movement between and across continents and regions is a relatively old-rooted phenomenon in the world’s history. it is part of the permanent process of change of every society and has always been an inherent contributor to, and a result of, structural transformation. the progressive shift of humankind from rural societies to city dwellers has been driven by a continuous process of migration, which has been accelerated worldwide over the last two centuries (mercandalli et al., 2019). however, in recent years, this corresponding author, e-mail: oumer.beriso@astu.edu.et. https://doi.org/10.20372/ejssdastu:v10.i1.2023.546 human mobility has become a main concern at international, national, and local levels of economic development. one type of this mobility is people’s internal migration within their national territory. it is characterised by rural-to-urban movement particularly in developing countries. moreover, the rapid and massive increase in rural-to-urban migration, mostly young migrants’ inflow to the city centres, has recently drawn the attention of stakeholders to the welfare of migrants in urban areas of developing countries. http://www.ejssd.astu.edu/ mailto:oumer.beriso@astu.edu.et oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 62 according to the economics of migration, migration has benefits and harms to both sending and receiving regions (jonathan, 2019). migrants can make significant contributions to host economies through labour supply, entrepreneurship, and consumption demands and to sending regions through remittances to their welfare. the economic gain for destination areas is due to the fact that incoming migration raises demand for basic commodities and increases the supply of labour force, which in turn increases employment, production, and is thus useful to the local economy. despite the positive effects of migration, particularly in urban areas, city administrators and the policymakers usually believe that unprecedented levels of urbanization characteristics in most developing countries due to inflows of people have resulted in burdens to local administrations and municipalities in urban areas. the impact can manifest itself in the form of economic burden, formation of slums and informal settlements in cities and urban areas (kibret, 2014). in this regard, proper management and efficient utilization of young migrants is essential for a developing country like ethiopia. ethiopia is the second most populous country in subsaharan africa (ssa) with predominately youth population (un, 2021). like other developing countries, ethiopia has been facing increasing challenges related to internal migration, which is becoming an image that distresses developments in urban centres. arguably, rural-to-urban migration is a principal component of rapid and unplanned growth of population in towns and cities in ethiopia, coupled with the country’s recent population growth. as internal mobility is not restricted by any explicit laws or policies, recent reports show that rural-to-urban migrants are rapidly moving to cities expecting better job and service opportunities as compared to rural areas (nganwa et al., 2015). despite the positive effects of migrants’ contribution to urban economic development, ethiopia’s urban centres have become more worried about the potential negative impacts of incoming migrants such as shortage in providing basic services, pressure on job provision, and informal business formation (which in turn contributes to risks in the formal business sector). currently, with most internal migrants coming to cities from rural areas, many migrants are facing difficulties partly linked to situations that explicitly or implicitly disadvantage them at the host city’s vicinity. this situation is associated with high urban youth unemployment, which is partly linked to the lack of urban labour market accommodation mechanisms. these mechanisms may include providing job search assistance and migrant-oriented support services (accommodation, training opportunities, convenient work environment, credit facilities, etc.). furthermore, the rural-to-urban migration is substantially complicated by the difficulty in obtaining urban registration or getting id cards and, consequently, difficulty in accessing certain public services, coupled with the negative attitude of local authorities towards migrants (nganwa et al, 2015). in combination with other factors emerging in recent years, notably the increase in rural-urban income gap, population growth in rural areas has led to a tremendous increase of migrants facing joblessness in major cities. . hence, special attention has been paid to how migrants fare in the urban labour market and particularly to how urban labour markets accommodate the inflow of these working-age migrants. the capacity of the urban economy in absorbing the economically active incoming urban labour force needs to be assessed regularly and appropriate employment policy implications should consequently be adopted. in this regard, despite the complexity of city life with many challenges and limited opportunities for migrants, the lobar market situation of urban migrants has not been well explored and the different coping strategies are seldom known. in view of this, this study aims to inquire how rural-to-urban migrants participate in urban labour market in cities by categorizing urban labour market into urban employment segments so as to identify and look into what determines the choice of urban employment segments. several studies have examined rural-to-urban migration in ethiopia (de brauw & mueller, 2012 and de brauw et al., 2013a). however, to the best of our knowledge, most migration studies in ethiopia lack information on the outcomes of migrant labour market in urban areas and its determining factors. thus, with a view to addressing this research gap in ethiopia and contributing to the labour market literature, this study estimated an econometric model to investigate determinants of migrants’ oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 63 employment choices in urban labor market. to this end, the study uses cross-sectional data obtained from ruralurban youth migrants in central oromia cities, ethiopia. 2. methods of the study 2.1. conceptual framework: labor force participation model consider urban labour market as an economy pertaining mainly to three types of economic activities or production units: the formal sector, informal sector, and household units. the formal sector is regulated and protected by law and it includes most decent jobs, whereas the informal sector is unregulated and unprotected (baffour, 2015). the rural-to-urban migrants of working age supply their labour to the urban labour market or to produce their own production formally or informally depending on their indirect utility maximization and individual background. consider a small closed economy with competitive urban labour employments categorized into five employment segments as: (1) self-employment segment in formal or informal sectors, (2) informal employment segment in private small businesses/ enterprises in formal or informal sectors, (3) formal employment segment in large private companies/enterprises in the formal sector (4) formal employment in public enterprises/offices in the formal sector, and (5) unemployment state or daily/casual wage labor in formal or informal sectors or in household production units. a standard choice model based on the comparative advantage hypothesis (johansson, 2000) in which these potentially risk-adverse young migrants choose to be in one of these five segments, argue that the choice between employment sectors depends on the difference in utility between the segments. hence, a migrant would choose one of these segments (say segment j) if her/his expected utility, measured by the expected income, exceeds that of all other alternatives. if someone cannot find a favoured segment job, the utility of such a sectorial job will be small. thus, winning her/his choice of segment j reflects both rationing and preference. hence, the employment segment selection and, as a result, income effects are indirectly reflected through, for example, individual intrinsic and familial characteristics (gender, age, marital status, family size) and human capital variables effects. thus, participation decision in the labour market is assumed to be a function of variables that influence a person’s expected offer wage and reservation wage. an individual chooses to enter the employment segment if the offer wage is greater than the reservation wage. human capital variables are expected to influence the offer wage and, hence, the segmental/sectorial selection, while individual characteristics may influence the reservation wage by affecting productivity in the home and demand for leisure. now, consider an individual migrant whose income is mainly allocated to consumption materials. let uij represent utility of the jth choice to the ith individual. if a migrant is employed in one of the alternatives, say the formal (f) employment segment, her/his utility from this segment would be defined as: , where i = 2, …; n is an index for a migrant; u is the migrant’s utility; h is migrant’s human capital variables; m is migrant’s individual intrinsic and familial characteristics, and w is a gross income of migrant from the employment. similarly, if she/he is working in the self-employment segment or other employment segments in the informal (i) employment, her/his utility can be written as: . in general, the utility of a migrant in the whole urban labour market economy can be expressed as:  hxuu ij , ; where x is other demographic, socioeconomic, and familial characteristics of an individual, j represents the different employment alternatives and j ∈ [1, 2, 3, …j]. hence, assuming utility is non-negative, uij > 0; for a given level of human capital and other characteristics, if a migrant is already in an alternative j employment providing consistent income and social advantages, the marginal utility (uhh) for reaching a better alternative should be declining. thus, under the assumption of rational migrants, as the level of human capital of the migrant, say the level of education, is not changing, given other characteristics, the marginal utility of alternative j is decreasing in the level of h → 0           h u h u u ijij hh however, as the level of education increases, the chances to access a better employment in the alternative j increases as well. therefore, the marginal utility associated with the progression toward this better employment segment may tend to increase; thus, the oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 64 marginal utility of alternative j is increasing in the level of h → 0           h u h u u ijij hh . similar arguments can be made also for other veriables. 2.2. empirical framework: multinomial logit model we are, therefore, modelling the employment segments as multi-categorical outcomes by focusing on the way in which migrants’ demographic, human capital, and other individual characteristics influence their decisions to participate in any of these urban lobur employment categories. hence, for such a case where more than two categories of exclusive choices in the dependent variable (dv) are possible, a multinomial logit (mnl) model is more appropriate (durbin and mcfadden, 1984). when one fits such a model, as discussed above, the dv would have, say 1, 2, 3,…, j possible outcomes; it exists more than one solution to β1, β2, …, βj that leads to the same probabilities: p1, p2, …, pj and thus the model has not an identified solution. hence, for identification, it requires normalization; one of the possible categories, say βj, should be defined as a base/reference category to be constant. this is achieved by arbitrarily setting one of the βj elements (let this βj=β1) equal to zero, so that the remaining β2, β3, …, βj measure the change relative to this reference category. hence we can think of the problem as fitting j–1 independent equations, and the j-1 outcomes are regressed vs. the reference category, to describe the relationship between the dv and the independent variables. now as disused above, job preferences are described functionally by well-behaved utility function, uij. hence, if uij is the maximum utility attainable for an individual i and if he/she chooses participation in alternative j supposing this indirect utility function can be decomposed into two and can be written as: (1) ijijij su  where sij is a non-stochastic component and itself a function of observed variables (sij = βjxi) and єij is a stochastic component. thus, this indirect utility function could yield an empirical specification of the form: )2(j..., 2, 1, = j ; n ,… 3, 2, 1, =i; ijjijij xu   where: n is the sample size; j is the number of employment segments; xi is a k x 1 vector of explanatory variables; βj is is a k x 1 vector of parameters to be estimated for choosing jth employment. hence, if the error term єij is mutually independent with a distribution ),,0(~ 2  nij mcfadden, 1973, we describe the mnl model as a function of individual migrant characteristics. now suppose the dv (yi) in equation (3) represents the nature of an individual’s current job status in any of the five employment segments: the unemployment state or daily laborer/casual worker (j=1), the self-employment segment (j=2), the informal employment in private enterprises (j=3), the formal employment in private enterprises (j=4), and the formal employment in public offices (j=5); the conditional-probability that a migrant i choose a particular employment category j, is mnl model as a function of explanatory variables xi is expressed as:           k j j ji ki kiik j j ikjk i i segmentanyforjjnifor x x segmentyprobp isthat x y jy ;,...,2,1;...,,1 exp exp :as odds,-log n therather tha piesp robabilit (3) original theof in terms written becan which model, m nl a of form general the j; ,… 2, = j; 1pr pr ln 1 ij '              hence, if the first category is set to be the reference category, so that the coefficient vector for the first choice, β1, is a null vector by normalization; then, we obtain a predicted probability for the reference category, and j -1 predicted probabilities for each nonreferenced category, relative to the reference category, as in (4) respectively.           categoryreferencenonforjj for x x jy categoryreferenceaforjj for x y j j ji ji i j ji i             ,...,4,3,2,1 exp1 exp pr& )4(;,...,4,3,2,1 exp1 1 1pr 1 1 4 1    however, the parameter coefficients obtained in the logistic estimation (the mnl model) composed of their sign serve to provide a sense of direction of the effects of covariates on participation and sectorial choice in the labour market, cannot be used for magnitude of impact analysis, but in terms of their relative risk ratio or oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 65 marginal effect (greene, 2007). hence, to examine the magnitude of impact, we have to calculate marginal effects (me) of the covariates on the probability of participation in each employment category, evaluated at the sample mean. the marginal effects of the explanatory variables are given by: )5( 1 1              j j jkjjkj k j pp x p me  the marginal effects measure the expected change in probability of a particular choice being made with respect to a unit change in an independent variable from the mean (greene, 2007). 2.3. data of the study the population of the study encompasses rural-urban youth migrants aged 15 – 30 who came to the urban study areas and have been living in the target cities for at least the last six months and at most for the last five years. we used a cross-sectional survey data collected from two urban centres in the central oromia, namely, adama and bushoftu-dukem cities, from may 12 – 27, 2021. the age of the migrants and their duration of living in the cities were purposively restricted to address ethiopia’s recent youth migrants’ manifestations in urban canters, as guided by a review of related literature (wambui, 2010; doğrul, 2012; and undesa, 2008). it is argued that different global and regional organizations, governments, and researchers in different countries adopted and used various age ranges in defining the term “youth” from the standpoint of their goals and activities (un, 2013). the un secretariat/unesco/ilo considers youth as persons between 15 – 24 years, while the un-habitat extends the upper limit to 32. the african youth charter considers a cohort of people aged 15 – 35 as youth. the ethiopia national youth policy defines youth as regiment of the society who are between 15 – 29 years (ministry of youth, sports & culture, 2004). accordingly, the present study adopts this national definition by extending the upper limit to 30 years. in line with ethiopia’s national youth policy (fdre, 2004), the study defines the term “youth” as those individuals in the age group 15 – 30. we used a multistage purposive, stratified, and random sampling technique to guide the sampling process. at the first stage, we purposefully selected the labor-intensive industry hubs in the country, namely, adama and bushoftu-dukem cities. then, taking into account the engagement of migrants in economic activities, we clustered the urban labour market purposively into five employment segments: the selfemployment segment in informal or formal sectors, the informal employment segment in small private-owned businesses in informal or formal sectors, the formal employment segment in private enterprise/companies in the formal sector, the formal employment segment in public enterprise in the formal sector, and the unemployment state or daily labor /casual work in the informal or formal sectors. lastly, after we distributed the sub-samples purposively and proportionally for each segment and further dispersed them proportionally to each city, we randomly surveyed the migrants from each cluster using a survey questionnaire. the survey instrument contains basic information on migrants’ demographic, socioeconomic and parental characteristics, and business environment. the samples were selected by the availability sampling method out of the initial 1000 proposed sample migrants assigned to the target cities in proportion to their anticipated migrant population; and who has identified as being employed in any of the five employment segments. the data were collected by trained data collectors or enumerators who were selected based on their experience and academic merits. accordingly, these enumerators were deployed to various places in the selected cities and gathered information from a total of 935 migrant respondents under close monitoring of supervisors. finally, a total of 883 participants' observations were identified due to the removal of missing/incomplete samples at the data inspection and screening stage.agriculture is the main source of revenue in the gumer district. the district comprises a largely diversified farming system that includes field crop production (which includes enset, eucalyptus tree, barley, bean, pea, and wheat as the main economic activities and livestock rearing (cattle, goat and sheep) as the second most important economic activity in the district. the major vegetables grown in the area are potato, cabbage, garlic, onion, endive, beetroot, carrot, and many more. the data obtained from fao (1991) shows the soil type in the district is mainly cambisols and plinthosols. oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 66 2.4. the study variables several studies on labour market in developing countries, including ethiopia, have pointed to demographic and socio-economic characteristics of individuals, business environment, and government policies as the main determinants of migrants’ participation in urban employment segments (muhdin, 2016, and millàn et al., 2010). however, the effect of these factors varies in time and space depending on specific situations in the study area/country, making it imperative to test the effects of these factors also in this study area. accordingly, based on the theoretical background and empirical results from different studies on rural-to-urban migration and migrants’ lobar market participation carried out in different countries, including ethiopia (wambui, 2010; shonchoy and junankar, 2014; kibret, 2014; msigwa and kipesha, 2013), the following explanatory variables were hypothesized and fitted to assess their influences on migrants’ participation in urban employment segments: migrants’ demographic and educational characteristics, migrants’ parental characteristics and migrants’ socio-economic factors in the city. 3. results and discussion 3.1. descriptive results the sample descriptive statistics for the relevant variables is presented in tables 1 to 5. as can be seen from table 1, out of the sampled migrants, 59% were males and 41% were females. about 69% of the migrants were from adama city, while 31% of them were from bushoftu city. in terms of their birthplace, about 54% were from rural areas, while 46% were from small urban areas in the country. the average age of the migrants is about 25 years, and the range is 15-30 years (table 2). the migrants have lived in the cities for about 3.26 years on average, with a range of six months to five years. at the time of the survey, about 33% of the migrants were already married and the average size of the migrants’ household was two. regarding the distance between migrants’ birthplace and their current destination, they travel an average of 203.8km from their birthplace. the descriptive result shows that the longest distance travelled is 900km by a migrant from the tigray region in the northern ethiopia, while the shortest is 10km from oromia. some of the migrants did migrate in steps to their intended cities of destination. in other words, they had previous migration history before they came to their present destination. table 1 migrants’ birthplace and cities of their destination birthplace city of destination sum sex within rural urban bushoftu adama female city/birthplace 40% 41% 37% 42% 41% within sex 53% 47% 28% 72% male city/birthplace 60% 59% 63% 58% 59% within sex 55% 45% 32% 68% total sample 54% 46% 31% 69% 100% source: own calculation table 2 migrants’ demographic characteristics variables mean sd min. max. age 24.65 3.53 15 30 household size 1.89 1.49 1 10 duration of living in city 3.26 1.45 0.5 5 distance to birthplace 203.80 174.66 10 900 percentage percentage migration experience 17% married 33% lack of city’s id card 30% received credit 34% job information deficiency 29% organization membership 45% skill/profession mismatch 13% faced dispute 56% access to social network 53% oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 67 as a result, 17% of them had migrated to another area before their current destination, while about 10% of them had migrated to more than one town/place before they came to these cities. about 53% of the migrants have obtained assistance from their social network contacts such as family members or relatives, close friends, or co-workers in the city. nearly 80% of the migrants had spent considerable time before getting a job. for 30% of them, this was due to lack of city’s id card. for 29% of them, it was due to lack of information on urban job availability. however, few of them had access to credit services from informal sources. regarding their challenges, 56% of them reported various challenges such as disputes with local youth/community members, sex-related abuses, mental or physical health problems, robbery or theft problems, and insecurity in their residential area & workplace. most of the self-employed migrants have no workplace to run their own-account business. of this group, 34% of them have been running their own-businesses by renting rooms from private owners, 24% on the main streets, and 16% by moving from place to place. the rest were running their own businesses around residential areas and at informal market places (locally known as ‘guliti’). regarding educational status of the migrants as can be seen from table 3, the majority of them have attended at least primary level of formal schooling. about 90% of them have attended formal schooling ranging from primary to tertiary level, with an average of 11years of schooling. about 21.51% of them have attended primary level formal education (i.e., junior secondary or below schooling, i.e., grade 1–8); 36% of them have attended senior secondary schooling, (grade 9 & 10); 27% of them have attended preparatory or tvet schooling, (grade 11 & 12 or tvet training), and 15% of them have completed university education. with regard to the educational and economic background of migrants’ parents (table 4), the average household size is seven. about 48% of the migrants’ mothers have received formal schooling, of which 42.12% have attended secondary school or below, and 5.78% have attended preparatory school or above. likewise, about 62% of migrants’ fathers have received formal education, of which 48.7% have attended secondary school or below, while 12.92% have attained preparatory school or above. occupationally, about 78.71% of the migrants’ fathers are engaged in farming, while 88.34% of their mothers are housewives. about 82% of parents own an average of 2.63 hectares of farmland. . on average, the migrants’ parents earn a yearly income of 27,035 birr, with a range of 800 to 1milion birr. as can be seen from table 5, the summary statistics shows that more males than females are likely to be employed in all employment segments. as a result, males make up the majority (68%) of the unemployed or daily labourers, followed by 60% of informal employees in both private enterprises and formal public employees, as compared with 53% of the self-employed. it is interesting to notice occupational accommodation of migrants by formal and informal sectors of the economy. when we look at the distribution of migrants over these sectors, we can see that 63.53% of the migrants are employed in the informal sector (in informal daily labours or informal self-employment or informal private-employment), while 28.43% are engaged in the formal sector (in private or public employments). most of the informal daily labourers are labour providers (presumably some of them as unskilled workers) in the form of instant labourers, technicians or construction workers, barbers, and brokers. the selfemployed are concentrated in retail trade, construction and market-oriented production activities, transport activities, and service activities such as shoeshine, street vending, and petty trading. in the self-employment segment, some female migrants are engaged in retail trade, but the overwhelming majority of them are engaged in street coffee vending and selling some foods and related items. table 3 migrants’ educational level sex junior secondary or below schooling senior secondary schooling preparatory or tvet schooling university degree female within level 39% 43% 43% 33% within sex 22% 38% 28% 12% male within level 61% 57% 57% 67% within sex 23% 35% 25% 17% total within sample 22% 36% 27% 15% oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 68 table 4 educational and economic background of migrants’ parents variables mean sd min. max. household size 6.75 2.70 1 24 farmland size 2.63 2.94 0 25 annual income 27,035 46,547 800 1,000,000 percentage percentage father’s schooling (secondary school or below) 0.49% father’s occupation (farmer) 79% father’s schooling (preparatory school or above) 0.13% mother’s occupation mother’s schooling (secondary school or below) 0.06% (housewife) 88% mother’s schooling (preparatory school or above) 0.42% farmland ownership 82% table 5 summary statistics of urban employment segments sex informal self-emp. informal private-emp. formal private-emp. formal public-emp. unemployed/ daily labourers female within category 47% 45% 40% 40% 32% within sex 30% 21% 19% 9% 21% male within category 53% 55% 60% 60% 68% within sex 23% 18% 19% 9% 31% total within sample 26% 19% 19% 9% 27% the informal private-employed are café, restaurant, and hotel workers, shop salespersons, transport operation backers, guards in private businesses or household units, and house workers. the formal privateemployed are mostly workers in private companies/factories, while formal public employees are government, union, plc, and co-operative workers. 3.2. econometric results and discussion parameter estimates from the mnl regression coefficients and their statistical significance with robust standard errors and the marginal effect estimates are presented in table 6. the data were checked with econometric diagnostic tests, whose result verified that there were no econometric diagnostic problems in the model. moreover, we used the robust standard errors to avoid/diminish effects of heteroscedasticity. we considered five labour market outcomes categorized as employment segments: informal selfemployment, informal private employment, formal private employment, formal public employment, and the unemployment or daily labourers, with the last outcome taken as the base/reference category. consequently, we obtained robust estimates for the four categories relative to the reference segment. the model result shows that most of the parameter estimates are of expected sign and different from zero at 5% or lower significance levels. the result reveals that the model fits significantly better than an empty model. this indicates that the urban labour market in the study area is heterogeneous and the decomposition of the labour market into employment segments is appropriate. the overall model is significant at 1% level and the pseudo r2-indicates that most of the explanatory variables have significant effects on migrants’ choice of employment segments. this means that a one-unit increase in respective variables could increase or reduce the likelihood of a migrant to be employed in the same unit according to the sign of the corresponding coefficients and magnitude of marginal effects, ceteris paribus, relative to the reference segment. estimates of the probability of employment choice are interpreted and discussed for all categories but only relating to the specified categories of employment that are statistically significant using marginal effects (mes) as in columns (2), (4), (6) and (8), respectively (see table 6), relative to the reference segment. 3.3. migrants’ demographic & educational background empirical result reveals that being female has a positive significant effect on all employment segments (all at 1%). the positive effect implies the oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 69 availability of opportunities for female migrants to be employed in all employment segments relative to their male counterparts. the corresponding marginal effect indicates that being female increases the likelihood of being employed in the self-employed, informal private, formal private, and formal public employment segments by 6.2%, 7.3%, 0.1%, and 2.6%, respectively, ceteris paribus. moreover, though the coefficients of sex (female) appear to have similar sign across the four segments, the effect of being female exhibits in informal employment sector about 3 times higher than in formal employment sector. thus, for female migrants, the relative probability of working in informal employment sector is higher than the chance of working in the formal sector. a migrant’s age has a positively significant effect on the formal public employment segment at 1%. the positive significant coefficients suggest that older migrants have higher employment probability in the formal public sector than their younger counterparts, ceteris paribus. mes result evinces that a one-unit increase in the age of a migrant resulted in an increase of the likelihood of being employed in the formal public segment by 0.6%. this result is in line with a finding in a similar study by gherbi and adair, 2020. marriage is positively significant to the selfemployed employment segment and is negatively significant to the informal private employment segment at 10% in each case. hence, the mes shows that marriage would increase the relative probability of being employed in the self-employment segment by 10%, while it decreases the likelihood of being employed in the informal private employment category by 13.3%, ceteris paribus. a migrant’s household size influences negatively and significantly the informal private employment segment at 5%. the mes estimates show that a oneunit increase in a migrant’s household size decreases the probability of being employed in the informal private employment segment by 2%, relative to the reference segment. this anticipation may reinforce the likelihood that employers in general, and the informal private employment employers in particular, are less willing to employ migrants who have larger family size, possibly with pre-school age children in the migrant’s family (which is supported by insignificant negative effect of the variable ‘migrant’s child dependency ratio). this could be because married migrants, as opposed to unmarried migrants, are more likely to work in self-employed sectors, while the same migrants are less likely to work in the informal private employment segment. empirical result exhibits that most of educational variables are positively related to all employment segments. however, the significant level and the magnitude of the effects of migrants’ educational level vary by employment category. senior secondary schooling has a negative significant effect on the formal public employment segment at a 10%. hence, having secondary education decreases the probability of being employed in the formal public employment sector, compared to having a primary education or no education at all, ceteris paribus. as the me estimate shows, completing senior secondary schooling would decrease the probability of being employed in the formal public employment segment by 4.8%. on the other hand, having preparatory or tvet schooling and university education has positive significant effects on the formal private and formal public employment segments at 5%. the corresponding me indicates that an additional year of preparatory or tvet schooling increases the probability of being employed in the formal private employment and formal public employment by 10.7% and 2.9%, respectively, ceteris paribus. the mes estimates show that an additional year of university education increases the probability of being employed in formal private and public employment segments by 10.8% and 7.8%, respectively. the finding is consistent with the finding of aynalem et al., (2016). 3.4. migrants’ parental characteristics with regard to the educational status of a migrant’s parents, the father’s secondary or below schooling is associated positively significantly with the informal private employment segment at 10%. hence, as the me estimate shows, a migrant whose father has attended secondary schooling or below is 7.8% more likely to be employed in the informal private employment segment, ceteris paribus. parents’ household size affects the informal private oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 70 employment segment negatively and significantly at 1%. the mes show that an additional number of parents’ household size would result in less likelihood of employment in the informal private employment segment by 1.5%. with regard to occupation of the parents of a migrant, the result indicates that those migrants whose parents are farmers are associated positively significantly with the informal self-employment and informal private employment segments at 1%. table 6 multinomial logistic regression result explanatory variables self-account employment informal-private employment formal-private employment formal-public employment (1) coefficient (2) m.e. (3) coefficient (4) m.e. (5) coefficient (6) m.e. (7) coefficient (8) m.e. migrants’ demographic and educational background sex (female) 0.801*** 0.064 0.816*** 0.075 0.488** 0.002 1.158*** 0.024 age -0.01 -0.003 0.008 0.000 0.001 -0.001 0.181*** 0.006 marriage 0.535* 0.100 -0.577* -0.133 0.29 0.052 -0.23 -0.009 household size -0.1 0.001 -0.196** -0.020 -0.19 -0.016 -0.17 -0.002 child-dependency ratio 0.59 0.057 -1.114 -0.178 -0.59 -0.178 1.655 0.049 migration experience -0.35 -0.032 -0.567 -0.084 0.17 0.072 -0.77 -0.021 senior 2ry schooling 0.15 0.002 0.306 0.036 0.44 0.060 -1.199* -0.048 preparatory/tvet educ. 0.02 -0.039 0.114 -0.023 0.751** 0.107 1.032** 0.029 university degree 0.18 -0.045 0.412 0.001 0.948** 0.108 2.582*** 0.078 migrants’ parental characteristics father’s 2ry schooling 0.17 -0.008 0.571* 0.078 0.32 0.021 -0.22 -0.016 father’s preparatory schooling -0.46 -0.081 0.469 0.114 -0.32 -0.053 0.003 0.002 mother’s 2ry schooling -0.16 -0.023 -0.079 -0.008 0.07 0.022 -0.19 -0.005 mother’s preparatory schooling 0.47 0.051 0.207 -0.002 0.41 0.039 -0.17 -0.014 father’s occupation 0.648* 0.063 0.619* 0.064 0.29 -0.009 0.218 -0.004 parent’s household size 0.05 0.011 -0.070*** -0.015 0.02 0.004 0.009 0.000 farmland ownership -0.661** -0.089 0.211 0.093 -0.610* -0.080 -0.1 0.004 parent’s annual income 0.427*** 0.023 0.464*** 0.034 0.553*** 0.048 0.393** 0.003 socio-economic factors of the migrants in the city city living duration 0.128 0.003 0.222** 0.024 0.152* 0.008 0.240* 0.005 access to training -0.965** -0.181 0.334 0.084 0.32 0.075 0.075 0.004 access to social network -0.08 -0.032 0.495 0.091 -0.34 -0.084 1.568** 0.053 access to workplace 2.757*** 0.516 – – – – – – access to job information -0.668 -0.063 -0.781 -0.095 0.341** 0.001 0.679*** 0.037 access to city id card -0.583** -0.042 0.992*** 0.137 -0.131 -0.047 0.235 -0.005 job mismatch with skill 0.348 0.044 0.401 0.060 -0.16 -0.057 -0.058 -0.002 access to any support 0.213 0.017 0.126 0.000 0.42 0.058 -0.731 -0.031 org. membership 0.07 0.009 -0.22 -0.055 0.158 0.027 0.799** 0.028 credit service -0.35 -0.096 0.479* 0.074 0.427* 0.057 0.499 0.013 dispute encounter in city -0.669** -0.102 -0.27 -0.025 -0.333 -0.097 -0.801** -0.023 access to registration & advisory service in city 0.415 0.041 -0.21 -0.092 0.747** 0.108 0.638* 0.015 origin and location of migration birthplace (small-urban) 0.623** 0.086 0.326 0.031 -0.11 -0.059 0.381 0.007 distance to birthplace 0.15 0.013 0.183* 0.023 0.04 -0.007 0.047 -0.001 regional origin (oromia) -0.602* -0.084 -0.633** -0.101 0.236 0.082 0.980* 0.042 constant -7.22*** -7.48*** -7.07*** -12.74*** log-pseudo likelihood = -1058.4524 wald χ2(132) = 484.21 pseudo r2 = 0.2284 prob > χ2 = 0.0000 source: author’s calculation, stata output. notes: significance code: *p<0.1, **p<0.05, ***p<0.01. m.e. stands for marginal effects. the reference category is unemployed or being a daily laborer oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 71 the mes estimate show that those migrants whose parents are farmers, compared to those whose parents are non-farmers, have more probability of being employed the informal self-employment and informal private employment segments by 6.3% and 6.4%, respectively. a parent’s annual income has a positive significant effect on all employment segments at l %. mes estimate indicates that a one-unit increase in a migrant parent’s annual income would increase the probability of being employed in the self-employment, informal private employment, formal private employment, and formal public employment segments by 2.3%, 4.8%, 3.4% and 3%, respectively. this result might be due to the fact that migrants from parents with relatively better annual income may be able to easily get initial capital to start their own business as selfemployed migrant in the informal employment segment, or they may have better inputs for searching jobs in the available urban labour market. these findings are consistent with the findings of amanuel (2016) and aynalem et al., (2016). in contrast, a parent’s farmland possession has negative significant effect on the informal self-employment and informal private employment segments, both at 5%. mes show that migrant parent’s farmland possession results in less likelihood of being employed in self-employment and in informal private employment segments by 8.9% and 8%, respectively. this could be due to the indifference state of migrants to join the self-employment and the informal private employment opportunities; with the existing high market prices and challenges in mind, they might consider a rational comparative advantage of working on their parents’ farmland by going back home. 3.5. socio-economic factors of the migrants in the city duration of migrants’ living in the city has a positive significant effect on the informal private, the formal private, and the formal public employment segments with p<0.01. this indicates that the longer a migrant has lived in the city, the more likely s/he is to be in most of the urban employment segments. the mes indicate that living in the city for one additional year would increase a migrant’s probability of employment in the informal private, the formal private, and the formal public employment segments by 2.4%, 0.8% and 0.5%, respectively ceteris paribus. migrants’ training opportunity has a negative significant effect on the selfemployment segment at 5%. this demonstrates that migrants who have participated in some training opportunity would have less relative probability of getting employed in the informal self-employment segment by 18%, as compared to those with no training. this might be due to inadequacy of the training or its mismatch with the actual migrant’s own-business activities. access to credit service has a significant positive effect on the informal private and the formal private employment segments at 1%. the significant influences only on these private segments could be related to the informality of the credit source itself, as most of the creditors obtained the money from nonfinancial sources. mes show that a migrant who has obtained credit service would have comparatively more probability of employment in the informal private and the formal private employment segments by 7.4% and 5.7%, respectively. access to workplace in the city has a positive significant effect on the self-employment segment at 1%. mes show that having a workplace for own business activity increases the probability of a migrant to be engaged in the self-employment segment by 51.6. having social network in the city affects the formal public employment segment positively and significantly at 5%. the mes show that having personal social network in the city increases the probability of a migrant being employed in the formal public employment segment by 5.3. the result is consistent with the previous studies such as amanuel (2016) and aynalem et al., (2016). access to job information has a positive significant effect on the formal private and formal public employment segments at 1%. the corresponding mes suggest that, for a migrant, having access to job information resulted in an increase of her/his likelihood of getting employed in the formal private and formal public employment segments by 0.1% and 3.7%, respectively. not having a city’s id card appears to influence the self-employment and informal private employment segments negatively and significantly at 1%. the mes evince that the probability of being employed in the self-employment and informal private employment segments declined by 4.2% and 13.7% for migrants without city’s id card, compared to those who have an id card, ceteris paribus. considering the variable ‘encountering dispute’, the result showed that oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 72 this variable has a negative significant effect on the selfemployment and the formal public employment segments at 5%. this indicates that migrants who have experienced any dispute during their stay in the city have faced distress in their life in the city, a situation that lowers their chance of being employed in the informal self-employment and the formal public employment segments by 10% and 2.3%, respectively. ‘being registered and getting advice’ in the city’s administration units have a positive significant effect on the formal private and public employment segments at 5%. mes indicate that being registered and receiving advice in the city’s administration units enhance a migrant’s probability of employment in the formal private and formal public employment segments by 10.8% and 1.5%, respectively, ceteris paribus. the empirical result shows that distance to the birthplace of a migrant has positively significant influence on the informal private employment segment at 10%. the result shows that a one-unit increase in a distance to the migrant’s birthplace is associated with 2.3% increase in the relative probability of a migrant to be employed in the informal private employment segment. being from a small town has a positive significant effect on self-employment segment at 5%. hence, being a migrant from a small town increases the likelihood that the migrant will be self-employed compared to migrants from rural areas by 8.6%, ceteris paribus. this might be due to the trend that, at the beginning of their career, youth in urban areas are often ready to engage in any available employment activities in the labour market as a survival strategy and to avoid unemployment, and they later transition to self-account employment at the new urban destination. 4. conclusions and recommendation this paper investigates determinants of rural-tourban migrants’ participation in employment segments in urban labour market in central oromia cities, ethiopia. the study used a cross-sectional data collected from youth migrants in selected central oromia cities. the study employed a mnl model to identify determinants of migrants’ participation in urban employment segments. for this purpose, the study categorized the whole sample of the study into five urban employment segments: the informal selfemployment, the formal private-employment, formal private-employment, formal public-employment, and the unemployment segments, with the last segment taken as a reference category. accordingly, these segments provided urban employment opportunities for 26%, 19%, 19%, 9% and 27% of the total surveyed youth migrants, respectively. descriptive results revealed that most of the migrants were from rural areas of the country. about 16.5% of them were transitory migrants who had migrated to other areas before their current destination. some of them had migrated to more than two towns/places before they came to their current city of residence. about 90% of the migrants have attended formal education from primary to tertiary levels of schooling. the majority of the migrants (86%) were from oromia regional state, particularly from arsi zones and bale zones, which take the largest zonal share within the region itself, followed by migrants from five shawa zones in this region. econometric model result exhibited that a migrant’s gender (female) and his/her parents’ annual income have a positive significant effect on the migrant’s employment in all employment segments. we can say that when the income of a migrant’s parents increases, the migrant is less likely to be unemployed or to be in a wage employment status. this shows that the migrant’s parental income, as a wealth-related factor of ruralurban migrant employment status, would have a positive effect on employment, as the migrant’s likelihood of being unemployed decreases. migrant’s marriage, getting workplace for own business, job information deficiency, being from small urban area and fathers’ occupation have positive significant effects on selfemployment. migrant’s training, lack of city’s id card, dispute in the city, being from oromia, and parent’s farmland possession have negative significant effects on the informal private employment. likewise, father’s secondary schooling and occupation, migrant’s duration in the city, job information deficiency and access to credit have positive significant effects on the informal private-employment. this segment is negatively influenced by marriage, household size, lack of city’s id card, being from oromia region, and parent’s household size. migrants’ preparatory or tvet schooling, university education, credit usage, and being registered and advised in the city have positive significant effects on the formal private employment, while parent’s oumer berisso and habtamu kebu ethiop.j.sci.sustain.dev., vol. 10 (1), 2023 73 farmland ownership has negative significant effects on this segment. lastly, migrants’ age, preparatory or tvet schooling, university education, having social network, organizational membership, and being from oromia region have positive significant effects on the formal public employment. on the contrary, migrants’ secondary schooling and facing disputes in the city of destination have negative significant effects on the segment. these findings have important implications for designing policies to address constraints of urban labor market segments and reduce their negative consequences in cities centers. the government should give more emphasis to targeted policies that will be more effective if they could take these characteristics into consideration. in this regard, there is a need to adopt policies and strategies that could enhance employment opportunities for the migrants in big city centers. well planned, coordinated, and concerted activities need to be undertaken on information on job availability, registration in local administration offices, providing city’s id card, advisory schemes, and community integration programs before and after migrants’ arrival in cities. besides, the government and municipalities should create suitable conditions by facilitating access to finance (start-up capital), creating small businesses and providing them with workplace, and providing entrepreneurship training for youth migrants to alleviate constraints to self-employment segment, which encourages the youth to create their own work rather than being job seekers. a further implication is that the government should focus on addressing gender relations as well as strengthening the linkage between informal and formal sectors. these include initiating policies that help to promote gender-specific affirmative measures such as provision of suitable childcare arrangements, which would make it easier for females to enter urban labour market both in the informal and formal sector employment. acknowledgement: the authors gratefully acknowledge the financial support of the cities alliance/unops and the swiss agency for development and cooperation. the opinions expressed herein are solely those of the authors and do not necessarily reflect the official 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(2010). determinants of employment in the formal and informal sectors of the urban areas of kenya. african economic research consortium, research paper, 194. nairobi.i. https://doi.org/10.9734/ajpas/2019/v5i230132 issn: 1998-0531 the ethiopian journal of sciences and sustainable development volume 2 number 1 may 2012 the comparison of the essential oils of the flowers of endod (phytolacca dodecandra) abdissa bekele, m. manikandan & aman dekebo 1 7 meeting middle level manpower to labor market needs: opportunities and challenges for tvet institutions birhane sime 8 15 a causal analysis model of supply chain factors impacting operations efficiency mengist hailemariam and karuna jain 16 22 economic efficiency of export–oriented cattle-fattening farms in east shewa zone: the case of adama city and its surroundings oumer berisso 23 34 a comparative study of occupational role stressors among academic officers of private and public higher educational institutions in oromia regional state of ethiopia kassim kimo 35 43 editor-in-chief dr. abebe belay; astu, adama, ethiopia p.o.box 1888, adama, ethiopia phone: +25122-1100056, fax: +251-221-100038 e-mail: rpo@astu.edu.et associate editors dr. ziyn engdasew: astu, adama, ethiopia dr. ing. simie tolla; astu, adama, ethiopia dr. lemi guta; astu, adama, ethiopia dr. tsetargachew legese; astu, adama, ethiopia dr. haileleul zeleke; astu, adama, ethiopia international advisory board prof. jang gyu lee; astu, adama, ethiopia prof. dr. g. albert; aau, addis ababa, ethiopia prof. tammo s. steenhuis; cornell university, usa dr. ing. zewdu abdi: aau, addis ababa, ethiopia dr. abebe fanta; haromaya university, dire dawa, ethiopia dr. kaba urgessa; ministry of education, addis ababa, ethiopia dr. berihanu adnew; ethiopian economic association, addis ababa, ethiopia dr. shimelis admasu; aau, addis ababa, ethiopia dr. alexander au; german academic exchange service, bonn, germany dr. solomon t/mariam; bahir dar university, ethiopia dr. asefa abagaz; mekele university, mekele, ethiopia http://213.55.101.26/index.php/component/contact/12-contacts/65-professor-jang-gyu-lee the ethiopian journal of sciences and sustainable development (ethiop.j.sci.sustain.dev.) volume 2, number 1, may 2012 issn: 1998-0531 copyright© 2012 astu contents page the comparison of the essential oils of the flowers of endod (phytolacca dodecandra) abdissa bekele, m. manikandan and aman dekebo 1 7 meeting middle level manpower to labor market needs: opportunities and challenges for tvet institutions birhane sime 8 15 a causal analysis model of supply chain factors impacting operations efficiency mengist hailemariam and karuna jain 16 22 economic efficiency of export–oriented cattle-fattening farms in east shewa zone: the case of adama city and its surroundings oumer berisso 23 34 a comparative study of occupational role stressors among academic officers of private and public higher educational institutions in oromia regional state of ethiopia kassim kimo 35 43 ethiopian journal of science and sustainable development 2012. 2(1) 1 the comparison of the essential oils of the flowers of endod (phytolacca dodecandra) abdissa bekele 1 , manikandan.m. 1 and aman dekebo 2 1 department of chemistry, haramaya university, p.o. box: 203, haramaya, ethiopia. 2 department of chemistry, adama science and technology university, p.o. box: 1888, adama, ethiopia. corresponding author. tel: +251 913119772, e-mail: aman_d00@yahoo.com. abstract the volatile oils of the flowers of phytolacca dodecandra collected from west shewa zone ginchi woreda and east wollega zone ebantu woreda, ethiopia have been examined separately using gc-ms. the essential oils were extracted by hydro-distillation from the flowers of p. dodecandra and analyzed using gas chromatographymass spectroscopy (gc-ms). the major components of essential oils from ginchi were cyclooctasulphur (34.01%), trans-nerolidol (15.44%), cismono(2-ethylhexyl) phthalate (12.59%) β-phenylethanol (11.93%), benzyl alcohol (9.30%), and from ebantu and eucarvone (26.56%), α-isophoron(15.46%), 2,4-ditert-butylphenyl5-hydroxypentanoate (11.30%), diacetamide (7.24%). variation in chemical composition and percentage of volatile components of the flowers oil of the plant from both sites might be due to the difference in soil type and climatic conditions. key words: phytolacca dodecandra, essential oil, phytolacaceae, flowers, endod introduction an ethnobotanical study conducted on different medicinal plants of ethiopia including phytolacca dodecandra (endod) which indicated that ethiopians have used traditional medicines for many centuries and the use of which has become an integral part of different cultures in the country (fisseha mesfin et al., 2009; gidey yirga,2010; tilahun teklehaymanot and mitutse giday, 2007). phytolacca dodecandra (endod), is a semisucculent straggling or scrambling shrub about 10 m height or more. it belongs to family phytolacaceae which includes about 16 genera and 100 species. the genus phytolacca contains about 35 species in tropical and subtropical regions (hedberg et al., 2000). the plant is distributed in east, west, central, and southern africa and parts of south america and asia (dalziel, 1936). in ethiopia, the species is naturally found at altitudes ranging between 16003000 m above sea level (wolde-yohannes, 1983). endod is the local name for phytolacca dodecandra or soapberry, a full shrub closely related to the american pokeweed (phytolacca americana). mailto:aman_d00@yahoo.com abdissa bekele, manikandan.m. & aman dekebo ethiopian journal of science and sustainable development 2012. 2(1) 2 endod has often glabrous but less commonly pubescent leaves and racemes, short pedunculate racemes with several flowers and bluntly starshaped berries (polhill, 1971). the berries of endod constitute various triterpenoid saponins, which possess potent and useful biological properties including detergent, molluscicidal (aklilu, 1965, 1970; parkhurstet et al., 1974; aklilu et al., 1991), spermicidal (stolzenberg and parkhurst, 1976), insecticidal, and fungicidal properties (dawit and solomon, 1994). the most scientifically studied use of endod is its molluscicidal property; it kills the intermediate host snails that harbor schistosomes that cause the disease schistosomiasis or bilharzia. in contrast to all other currently available molluscicides, endod berries have also dual purposes: it is used as soap for washing clothes and as molluscicide for killing schistosome transmitting snails. the use of endod for schistosomiasis control is considered cheaper, environmentally safe, biodegradable, more readily available plant molluscicide than the currently available synthetic chemicals (kloos and mccullough, 1983; lambert et al., 1991; molgaard et al., 2000). although the flowers of endod contain essential oils, to the best of our knowledge, there was no previous report on the analysis of the essential oils of the flowers part of endod. nowadays, the plant products have a wide range of applications in perfume and cosmotic industry, in food technology, in aroma and pharmaceutical industry. these wide applications of the plant products initiated us to investigate the constituents in the flowers of p. dodecandra from the two sites in ethiopia, using gas chromatography-mass spectrometry. materials and methods plant material the flowers of p.dodecandra were collected from two different places in ethiopia namely, ebantu woreda, east wollega, oromiya region, and ginchi west shewa, oromiya region during flowering in november, 2009. the botanical specimen was identified and deposited at haramaya university, herbarium; center, ethioipia. the flowers were collected in plastic bags and then exposed to room temperature for drying for five days. isolation of the essential oils the ground and air dried flowers (90.0 g) of p.dodecandra, collected from ebantu site, were placed in a round bottom flask fitted with clevenger-type apparatus and a glass condenser and hydro-distilled for 3 hrs at atmospheric pressure. after the hydro-distillation, the essential oils were separated by separatory funnel using chloroform (acs grade of u.k.) and were dried over anhydrous sodium sulphate (na2so4). the obtained yield was (0.032 g, 0.032%). similarly, the ground and air dried flower (90.0 g) of p. dodecandra collected from ginchi site, was also hydro-distilled for 3 hrs at atmospheric pressure, separated and dried. this yielded essential oils (0.39 g, 0.39%). the oils were then sealed in glass vials and stored in fridge until gc/ms analysis (anonymous, 1996). gas chromatography-mass spectrometry (gc-ms) the specifications of gc-ms for analysis of essential oils are agilent 19091s-433 msd equipped with a hp-5ms 5% phenyl methyl siloxane of capillary column (30 m x 0 .25 mm x 0.25 µm). the oven temperature was programmed abdissa bekele, manikandan.m. & aman dekebo ethiopian journal of science and sustainable development 2012. 2(1) 3 from 40-240 o c at a rate of 3 o c/min and it was held at 40 o c for 2 min and at 240 o c for 5 min. injector temperature was at 250 o c and transfer temperature was at 260 o c. the carrier gas was helium flowing with the flow rate of 1.5 ml/min with a linear velocity of 31.5 cm/s, the split ratio was 1/60 with ionization energy of 70ev at scanning time of 1 s and the mass range was 40-500 amu. the constituents were identified by processing of the raw gc-ms data with chemstation g1701ca software and comparing with nist and from retention times and mass spectra of standard compounds. relative amounts of detected compounds were calculated based on the peak areas of the total ion chromatograms (faridahanim, et al., 2007). results and discussion the essential oils of the flowers of p. dodecandra from ginchi woreda and ebantu were obtained by hydro-distillation and analyzed by gc-ms shown in fig 1 and 2. the major constituents of the essential oil of the flowers of p.dodecandra from ginchi were benzyl alcohol (9.30%), β-phenylethanol (11.93%), cis-trans-nerolidol (15.44%), cyclooctasulphur (34.01%), mono (2-ethylhexyl) phthalate (12.59%) as shown in table 1. similarly the essential oils from that of ebantu has diacetamide (7.24%), αisophoron(15.46%), eucarvone (26.56%), 2,4-ditertbutyl phenyl-5-hydroxypentanoate (11.30%) (see table 2) as major constituents. the percentages of the yielded constituents from both sites were different; that is 0.032% for ebantu and 0.39% for ginchi sites. this variation might be because of environmental difference, the variation of safety when the flowers were collected, the fertility of the soil, temperature of the area and other different factors. when these essential oils from both places were analyzed by gc-ms, compounds with different percentage were identified after processing of the raw data by gc-ms with chemstation g1701ca software and by comparison of those spectral data with those of nist library and their ms spectral data with standard compounds. relative amounts of detected compounds were calculated based on the peak areas of the total ion chromatograms. 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00 65.00 70.00 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 14000 15000 16000 17000 18000 abundance 1 2 3 4 5 7 6 8 9 10 11 figure 1: gas chromatogram of the hydro-distilled oil of the flowers of p. dodecandra from ginchi abdissa bekele, manikandan.m. & aman dekebo ethiopian journal of science and sustainable development 2012. 2(1) 4 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 30000 32000 34000 time (min) abundance 1 2 3 4 5 6 7 8 9 10 11 12 13 figure 2: gas chromatogram of the hydro-distilled oil of the flowers of p. dodecandra from ebantu table 1 shows eleven components with their retention time, kovats index and percentage composition of essential oil from ginchi site. the table shows the presence of five major components namely, cyclooctasulphur (34.01%), cis-transnerolidol (15.44%), mono (2-ethylhexyl) phthalate (12.59%), β-phenylethanol (11.93%), and benzyl alcohol (9.30%), while six of them γphenylpropanol (4.97%), peonol (4.68%), 2,4-ditertbutylphenyl-5-hydroxypentanoate (3.12%), αisophoron (1.94%), 2,5-dimethyl-3-4-hexanediol (1.26%), 3-amino-2-cyclohexanone (0.75%), were noted to be relatively the minor constituents. the identity of the major component (cyclooctasulphur) needs to be confirmed by running gc of a standard sample. however due to a difficulty of obtaining the standard sample, we were not able to confirm it for the time being. table 1: chemical composition of the hydro-distilled oil of the flowers of p.dodecandra from ginchi peak no. rt min ki lit ki %com. compounds 1 15.389 1036 1010 9.30 benzyl alcohol* 2 19.148 1136 11.93 β-phenylethanol* 3 19.466 1097 1088 1.94 α –isophoron 4 24.687 1235 1207 4.97 γ –phenylpropanol 5 28.961 1437 1438 4.68 peonol 6 36.898 2255 3.12 2,4-ditert-butylphenyl-5hydroxy pentanoate 7 37.068 1106 0.75 3-amino-2-cyclohexenone 8 38.836 1564 1550 15.44 cis,trans-nerolidol* 9 52.784 1013 1.26 2,5-dimethyl-3,4-hexanediol 10 54.373 1845 34.01 cyclooctasulphur* ? 11 69.395 2162 12.59 mono(2-ethylhexyl) phthalate* * major components of the oils abdissa bekele, manikandan.m. & aman dekebo ethiopian journal of science and sustainable development 2012. 2(1) 5 table 2 shows the thirteen components with their retention time, kovats index and percentage composition in the essential oils from ebantu site. four of the components eucaryone (26.56%), αisophoron (15.46%), 2,4-ditert-butylphenyl-5hydroxypentanoate (11.30%) and diacetamide (7.24%) were the major constituents of the essential oils, whereas nine of them n-decanoic acid (6.24%), eicosane (6.22%),4-oxoisophorone (6.11%), o(trimethylsilyl) phenol (5.53%), 2-ethylhexylester (5.27%), benzaldehyde (2.84%), acetophenone (2.65%), (e)-2-ethoxyethenylacetate (2.41%), benzylalcohol (2.15%) were found to be relatively minor constituents. table 2: chemical composition of the hydro-distilled oil of the flowers of p. dodecandra from ebantu. peak no. rt min ki lit ki % com. compounds 1 11.835 965 965 2.84 benzaldehyde 2 12.021 955 7.24 diacetamide* 3 15.388 1036 1010 2.15 benzyl alcohol 4 16.845 1037 2.65 acetophenone 5 19.455 1097 1088 15.46 α-isophoron* 6 20.594 1268 1108 6.11 4-oxoisophorone 7 23.204 869 2.41 (e)-2-ethoxyethenylacetate 8 24.115 1343 26.56 eucarvone * 9 28.950 978 1058 5.53 o-(trimethyl silyl) phenol 10 36.130 1972 5.27 sulfurous acid,2-ethylhexyl ester 11 36.893 2255 11.30 2,4-ditert-butylphenyl-5hydroxypentanoate* 12 44.248 2000 2000 6.22 eicosane 13 52.858 1473 6.24 n-decanoic acid * major components of the oils as shown in tables 1 and 2, most of the essential oil constituents of the flowers from both sites were different and only a few of them were similar. the similar components of essential oils in both sites were benzyl alcohol, α-isophoron, 2,4-ditertbutylphenyl-5-hydroxypentanoate. the benzyl alcohol with kovats index of 1010 and 9.30% composition is major for ginchi site and minor for ebantu site while α-isophoron with kovats index 1088, 15.46% composition and 2,4-ditertbutylphenyl-5-hydroxypentanoate kovats index 2255, 11.30% composition were major for ebantu site and α-isophoron (1.94%) and 2,4-ditert-butylphenyl-5hydroxypentanoate (3.12%) were minor in ginchi. one of the most important perfume ingredients made from benzene is 2-phenylethanol. as benzyl alcohol and bezaldehyde are benzene derivatives they may also be used as ingredients of perfume. cis, transnerolidol identified as components of essential oils of flowers of endod is an oxygenated terpenoids. the terpenoids form the largest group of natural odorants, so it is only to be expected that they also form the largest group of modern fragrance ingredients. thousands of different terpenoid structures occur in perfume ingredients, both natural and synthetic. as far as perfume materials are concerned, the most important members of the terpenoid family are the oxygenated monoterpenoids (pybus and courtney, 2006). abdissa bekele, manikandan.m. & aman dekebo ethiopian journal of science and sustainable development 2012. 2(1) 6 conclusion even though several bioactive compounds were previously isolated and characterized from berries of endod, there has been a research gap till date on volatile constituents of oils from flowers of endod. volatile components from plants are mainly used in aromatherapy, in perfumery as insect repellants and others. based on the geographical location and soil type and seasons of the year components and their percentage composition of volatile components of endod may vary. in this study, flowers of endod were collected from two sites. from the flowers of this plant, the essential oils were extracted by using hydro-distillation; from these oils, the major components of the essential oils were analyzed using gc/ms. the major essential oils identified were benzyl alcohol (9.30%), βphenylethanol (11.93%), cis, trans-nerolidol (15.44%), cyclooctasulphur (34.01%), mono (2ethylhexyl) phthalate (12.59%) from ginchi site and diacetamide (7.24%), α-isophoron(15.46%), eucarvone (26.56%) and 2,4-ditert-butyl phenyl-5hydroxypentanoate (11.30%) from ebantu. variation in chemical composition and percentage of volatile components of the flowers oil of the plant from both sites might be due to the difference in soil type and climatic conditions. in the further, bioactivity tests and comparative studies on volatile components of oils this part of the plant from different regions is recommended. acknowledgements we thank to dr. tarekegn berhanu and w/t esrael habtu for their assistance in running gc-ms experiment in the quality and standards authority of ethiopia. the financial assistance from ministry of education of ethiopia is gratefully acknowledged. references aklilu lemma (1965): a preliminary report on molluscidal properties of phytolacca dodecandra. ethiop. j. med . 3:187-190. aklilu lemma (1970): laboratory and field evaluation of the molluscicidal property of phytolacca dodecandra. bull.who. 42:597-617. aklilu lemma, wold-yohannes lemma, praleigh, p.c., klerks, p.l. and lee, h.h. (1991): endod is lethal to zebra mussels and inhibit their attachment. j. shellfish. res. 10:361-365. anonymous, p. (1996): european pharmacopoeia (3 rd ed.) strasburg,france : council of europe, p121-122. dalziel, j.h. (1936): the usefull plants of west africa .crown agents, london.235p. pybus, d h. and courtney, f. (2006): the chemistry of fragrances from perfumer to consumer (2 nd ed), rsc publishing, uk, p54-106. dawit abate and solomon fesseha (1994): in vitro and in vivo antifungal activity of endod (phytolacca dodecandra).in: present status and future trends of research on endod and schistosomiasis in ethiopia. proceedings of a preparatory workshop held in nazereth, addis ababa university press.62-66p. faridahanim, m. j., osman, c. p., ismail, n. h. and awang, k. (2007). analysis of essential oils of flowers. mal.j.an.scie.11:269-273. abdissa bekele, manikandan.m. & aman dekebo ethiopian journal of science and sustainable development 2012. 2(1) 7 fisseha mesfin, sebsebe demissew and tilahun teklehaymanot (2009): an ethnobotanica study of medicinal plants of wonago woreda, snnpr, ethiopia. j. ethnobiol. and ethnomed., 5:28. gidey yirga (2010): ethnobotanical study of medicinal plants in and around almata, southern tigray, northern ethiopia. curr. res. j.biol. sci., 2: 338-344. hedberg, i., mesfin tadesse, sebsebe demisew and edwards, s. (2000): flora of ethiopia and eritrea, addis ababa, ethiopia. 2: 59-60, 274-275. kloos, h. and mccullough, f.s. (1983): review of plants with recognized molluscicidal activity. proceedings on plant molluscicides of the scientific working group on schistosomiasis.geneva, switzerland. 20-23 december. lambert, j.d., temmink, j.h., marquis, j., parkurst, r.m., lugt, c.b., schoonen, a.j., holtz, k., warner, j.e., dixon, g., wold-yohannes lemma and desavigny, d. (1991): endod: safety evaluation of molluscicide. regul. toxicol. pharmacol. 14: 189201. molgaard, p., chihaka, a. lemmic, e., furu, p., windberg, c., ingerslev, f and halling-sorensen, b. (2000): biodegradability of molluscicidal saponins of p. dodecandra. regul.toxicol. pharm. 32:248-255. parkhurst, r.m, thomas, d.w., skinner, w.a. and cary, l.w. (1974): molluscicidal saponins of phytolacca dodecandra: lemmatoxin. can. j. chem. 52: 702-705. polhill, r.m. (1971): phytolaccaceae. in: flora of tropical east africa. government printer, london. p. 112. stolzenberg, s.j and parkhurst, r.m. (1976): blastocidal and contraceptive actions by an extact and compounds from endod (phytolacca dodecandra). contraception, 14:39-51. tilahun teklehaymanot and mitutse giday (2007): ethnobotanica study of medicinal plants used by people in zegie peninsula, northwestern ethiopia. j. ethnobiol and ethnomed., 3:12. wold-yohannes lemma (1983): past and ongoing agrobotanical studies of phytolacca dodecandra (endod) in ethiopia.. in: final report of the international workshop, lusaka, zambia, 24-27 march. ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 8 meeting middle level manpower to labor market needs: opportunities and challenges for tvet institutions birhane sime school of pedagogy, adama science and technology university, p.o.box 1888, ethiopia, e-mail: birhane_200@yahoo.com abstract the purpose of this study was to examine the extent to which tvet institutions identify and use market opportunities and the major challenges they face in matching manpower supply to the demand for the skilled workforce in the labor market. to meet the purpose of the study, the researcher used quantitative survey research method supported by qualitative data. the participants of the study were 45 members of tvet management (process owners), 45 department heads, and 73 tvet graduates (employed and unemployed), 9 tvet principals, 3 micro and small enterprise office heads, 12 employers and 9 tvet heads from 6 districts and 3 administrative zones. questionnaires and semi-structured interviews were employed to solicit data from key informants in the study setting. data were analyzed through qualitative and quantitative analysis methods. the study results showed that tvet institutions were found weak in spotting actual skill needs in the labor market, implementing cooperative training and involving stakeholders in matching competences to labor market needs. generally, tvet institutions do not effectively utilize job opportunities currently available in their respective areas. hence, the researcher recommends the importance of strengthening network and partnership program between tvet institutions and stakeholders in areas of job placement, work attachments, advice on courses, part-time teaching staff and financial assistance. key terms: labor market, middle level manpower, tvet institutions, demand, supply introduction technical and vocational education and training refers to the deliberate interventions of bringing about learning which would make people more productive in designated areas of economic activity (ilo, 2001). according to unesco (2002) the major objective of technical and vocational education and training is to supply qualified workforce ranging from lower to middle skill levels. to achieve this objective, tvet providers should develop the capacity to produce trainees with skills and knowledge of the competitive requirement and institutional mechanisms that will ensure the establishment of excellence of instruction and development of employment-linked competencies among graduates (unesco, 2003). various scholars and organizations have identified the role of tvet for development, among these ilo (2001), specified the role of tvet as an instrument that creates new employment opportunities and income-generating activities in the formal and informal sectors of the economy. moreover, it is extremely well-positioned to contribute to global development, participation and interaction. mailto:birhane_200@yahoo.com birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 9 however, according to moe (2007) the task of matching supply of skilled manpower to the demand in the labour market is so challenging, and factors hindering its implementation are also multidimensional and abundant. in this regard , the data obtained from oromia education bureau (2005) between in the academic years 2002-2005 depicted that 16,046 tvet trainees graduated and out of those graduates only 2,737 (17.05%) got employment opportunities in government, private, cooperatives and as self-employees. among these the most employed graduates were those who graduated in the area of construction, electricity and electronic technologies. nevertheless, in the same fiscal year, there were more than 2,468 private investment projects, which were assumed to create 131,988 permanent and 594,630 temporary job opportunities for middle level tvet graduates and other unemployed citizens in oromia regional state (oromia investment profile, 2005). this indicates that tvet institutions are unable to use the opportunities existing in their environment. recently, the study made by oromia regional tvet agency (2009) also confirmed the mismatch in supply and demand of middle level skilled manpower in the region. according to the agency, the rate of responsiveness of tvet programmes to regional private investment sector is less than 40%. in the same way, tracer study result which was conducted in arsi administrative zone in september 2010 in six tvet institutions, showed that out of 722 tvet graduates of 2009/10, only 128 (17%) of them got employment opportunity (self-employed, organized in cooperatives & employed in private & government firms). a similar study, conducted by adama tvet college, revealed that out of 2,596 tvet graduates of 2008 2009/10 in different levels, only 610 (23.5%) graduates got job opportunities. this problem is also true in the case of east shoa zone tvet department. the analysis of the document showed that, out of 845 tvet graduates of 2009/10 only 298 (35.3%) were employed in different sectors, organized in cooperatives and as self-employee. from the above data, the effectiveness of training being offered is already under question. because, as stated by middleton et al. (1993) basically the effectiveness of the training depends on the extent to which trained workers use their skills in employment. besides, a rise in the unemployment rate reflects not a growing scarcity of jobs but rather a change in the expected costs and benefits of looking for and accepting employment (heyne, 1991). hence, the purpose of this study was to investigate the extent to which tvet institutions identify and use market opportunities and the major challenges they face in matching manpower supply to the demand for the skilled workforce in the labor market. therefore, in light of the above statements, the study tried to get appropriate answers to the following basic questions: 1. what measures were taken by tvet institutions to endorse employment oriented vocational and technical training? 2. what opportunities are in place to maximize the employment rate of tvet graduates? 3. what challenges do tvet institutions face to respond to the competence needs and qualification requirements in the labor market? birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 10 materials and methods the methodological approach used in this study was quantitative survey research method supported by qualitative data. to make the study manageable, purposive sampling technique was used to select nine tvet institutions which were established before the implementation of ethiopian national tvet strategy of 2008 and which are found in adama, arsi and east shoa administrative zones of oromia regional state were included in the study. moreover, by using snowball sampling techniques 51 employed and 22 unemployed a total of 73 (32.3%) tvet graduates of the same level (level-3) and fields of training (construction, electricity and automotive technology) were included in the study. furthermore, by using simple random sampling techniques 45 process owners and 45 department heads were included in the study. in addition, 9 tvet principals, 3 tvet heads, 12 employers of tvet graduates and 3 heads of micro and small enterprises were purposely selected as sample respondents. for this purpose, questionnaires and semi-structured interview were mainly employed to solicit information from the group. in addition, various reports and documents in tvet institutions were reviewed and used as secondary source of data. to do this, the researcher used three years of data (20082011). finally, the raw data collected through a quantitative approach were tallied, tabulated, and analyzed by using means and standard deviations. moreover, data collected through the semistructured interview and open-ended questionnaire were analyzed by reviewing common ideas reflected and key points related to the objectives of the research. results and discussions matching competences to labor market needs tvet quality is a very vast issue and requires a broad spectrum of actions. in this regard, process owners and department heads were asked to evaluate actions taken by tvet institutions for effective utilization of labor market opportunities in promoting employment oriented tvet program using a five point scale ranging from very low (1) to very high (5). table 1: current institutional practices (n=90) no. items mean sd 1.1 industrial experience of teachers were improved 2.76 .73 1.2 cooperative training was conducted 1.74 .86 1.3 pilot test was performed before large scale implementation 1.92 1.44 1.4 tracer study was conducted 1.38 .63 1.5 government sector plans were used as input for designing training programs 1.67 1.09 one of the distinguishing characteristics of technical/vocational education is its linkage with industries and companies. in this regard, unesco (1973) noted that a vocational teacher should have industrial or comparable experience. concomitant with this, item 1.1 was posed to informants with the intention to identify actions taken by tvet institutions to improve the industrial experience of trainers. accordingly, more than average of the informants indicated that tvet institutions try to improve the industrial experience of teachers with mean average 2.76. item 1.2 of table i deals with the cooperative training. according to moe (2007:6) cooperative training makes trainees acquire the necessary birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 11 practical skills reducing the existing skill gap and meeting the challenges of constant change in markets and technologies. in this regard, a question was posed to tvet principals and department heads and the overwhelming majority of them responded negatively (mean = 1.74). this may be due to the less emphasis given by the tvet institutions to the importance of cooperative training and unwillingness of owners of firms to accept trainees. evidently, the interviews held with the employers and tvet officials also confirmed the unsuccessfulness of cooperative training program among seven tvet institutions. the reasons given by owners of industries were the dissimilarity of training material, fear of wastage of production materials and safety reasons. however, two factories, namely: wonji sugar estate and wonji paper factory currently have started cooperative training with wonji tvet institution. similarly, nazareth tractor factory and moenco toyota garage, transethiopia, tekur abay and bekelcha transport industries, telecommunication and ethiopians electric light corporations have started cooperative training with adama tvet college. informants were also asked three other questions which focused on tracer study, pilot testing of new programs before large scale implementation and using government sector plans as input for designing training programs. as it is indicated in table 1 item 1.3, 1.4 and 1.5, almost all tvet institutions were weak in conducting tracer study, pilot testing and using government sector plans as input to adjust their training program (mean average less than 2.00). from this we can deduct that, it is not unwise to infer the fragile nature of tvet institutions in supplying manpower needed in the labor market. stakeholders involvement in tvet system tvet is considered as an important element in human resource development with the general objective of equipping learners with adequate knowledge and skills for life and the labor market (unesco, 2002). to achieve this intended objective and to make tvet system employment oriented, demand-driven and responsive to the economic development of the country, the concerned stakeholders should participate in planning, programme implementation and monitoring and evaluation of the tvet activities carried out in the training institutions (niche, 2010). in this regard, process owners and department heads were asked 8 questions about the role played by the stakeholders to make tvet graduates competent and effectively utilize the job opportunities available in the world of work especially in their firms. table 2: major areas of stakeholders involvement (n= 90) items mean sd 2.1 supervise the implementation of the program 2.33 .67 2.2 providing career guidance service 2.26 .90 2.3 financing training program 1.25 .43 2.4 providing training facilities 1.38 .48 2.5 monitoring training quality standards 2.61 .95 2.6 involving in training of trainers 1.36 .48 2.7 providing information that help to adjust the tvet curriculum 3.11 .91 2.8 paying pocket money for the trainees 1.07 .27 as it can be seen from table 2, process owners and department heads agreed that stakeholders birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 12 moderately participate in monitoring training quality standards and in providing information that help to adjust the tvet curriculum with mean average 2.61 and 3.11 respectively. however, the participation of stakeholders is low in supervising the implementation of tvet program and in providing vocational and guidance service for trainees (mean between 2.002.50). moreover, as it was clearly indicated in table 2 there was almost no active participation of stakeholders in financing training program through contributing resources, providing training facilities, training of trainers, and paying pocket money for the trainees. the interview responses also confirmed the findings. in general, this result is inconsistent with the contentions of osborne and geebler (1992) findings which was supported by unesco (2003) that declared the importance of participating stakeholders in tvet system, especially, in identifying training needs, establishing and monitoring training standards, harmonizing activities, supervising manpower demand and supply and evaluating the training system in terms of efficiency and effectiveness. job opportunities currently available in the study area the vocational education and training system in ethiopia is seen as a key supplier of the skilled workforce required to sustain the growing economy (moe, 2008). a question was presented to all groups of informants to specify job opportunities currently available in adama and surrounding towns. through structured interview and open ended responses, informants stated that jobs related to wood work, automotive, maintenance service, metal and electricity are available in the labour market. however, repairing electronic materials and automotive related works are only available for few graduates who are able to compete with workers already in the labour market. furthermore, informants added other types of jobs currently available in the labour market. some of the jobs are: textile and garment, food processing, and road construction (cobblestone). specifically, mse office heads showed that cafeteria, hair dressing, ict and other businesses are also available jobs for graduates who have the need to establish their own firms or to be organized in mse. moreover, according to adama town investment office 2011 final report, since 2007/8, 463 different types of industries have been established in adama town and created job opportunities for 21,649 citizens out of whom 6.10% are tvet graduates. in addition, to implement the five year developmental and transformation plan, government sectors have a great desire and plan to get skilled manpower from tvet institutions. major challenges and issues faced by tvet institutions management members (process owners), tvet graduates, and department heads were given criteria to assess major challenges facing tvet institutions in meeting labor market needs. as it is seen from the data obtained in table 3 above item 3.1, the training facilities (training machines, hand tools, and teaching aids) in relation to the number of students are inadequate. an interview response of seven tvet principals, two tvet zone and five district heads also revealed birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 13 that the training facilities of tvet institutions are far below what has been stipulated by the 2008 ethiopian tvet strata. table 3: within the school factors (n=163) items mean sd 3.1 lack of training facilities 4.34 .694 3.2 low supply of consumable raw materials for practical training 4.15 .799 3.3 trainers lack of industrial experience 3.34 1.146 3.4 the training equipment available in tvet institutions are less relevant to local situation 3.98 0.936 3.5 difficulty in securing appropriate financing for implementation of anticipated framework 3.41 1.131 3.6 problem of predicting the number of graduates required from vocational training institutes in terms of occupational categories 3.60 0.607 on top of this, other facilities such as: computers, books, reference materials, journals, and textbooks are still insufficient and this has aggravated the problem. shortage of consumable raw materials for training also affected the training process. furthermore, informants declared that the training machines in the workshop are less relevant to the local situation and the technologies used in the environment. in their responses to the open ended questions, the respondents stated that the training machines in the workshops are partially operated by the trainers and trainees and they are less relevant to the content of the module. according to the majority of tvet principals the other major barriers which badly affected the training system are: cost of tvet programs, inadequacy of training budget and insignificant financial support from different funding agencies. this reality calls for some mechanisms like income generating to reduce the burden of government in spending on tvet and restrain budgetary constraints. informants were also asked about industrial experience of trainers. as one can see from table iii item 3.3, trainers’ lack of industrial experience may be among critical constraints that handicapped trainers’ efforts. the mean value 3.34 clearly indicates the prevalence of the problem. the other problems which encountered tvet institutions were low competence of management in measuring actual skill needs in the labor market and difficulty of predicting the number of graduates required from vocational training institutes in terms of occupational categories. table 4: out of the school factors (n= 163) items mean sd 4.1 mismatch between employable skills and tvet curriculum 4.27 0.816 4.2 lack of capital for self employment 4.00 0.785 4.3 technological change 4.06 0.916 4.4 challenge of getting relevant raw materials for training 4.22 0.916 as shown in table iv above, informants were asked to answer the extent to which external factors affect tvet institutions in matching competences to labor market needs. according to the finding of this study, the external challenges facing tvet institutions in supplying middle level manpower needed in the labor market are: mismatch between employable skills and tvet curriculum (mean= 4.27), lack of capital for self employment (mean=4.00), technological changes birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 14 (mean=4.06) and inadequacy of raw materials for the process of training (mean=4.22). in general, weak coordination and lack of willingness of concerned bodies to participate in tvet system and the impact of technology and economy affected tvet institutions not to utilize market opportunities in reducing the rate of graduate unemployment. conclusion the study result shows that various kinds of job opportunities are available for tvet graduates in adama, arsi and east shoa administrative zones. however, the effective utilization of market opportunities in adama and surrounding towns are affected by the low capacity of tvet institutions to cater their training program for actual skill needs of the labor market and weak involvement of stakeholders. in addition, fragile implementation of cooperative training, lack of adequate and reliable labor market information, absence of tracer study result, inadequacy of training facilities and budget, change in technologies are other challenges facing tvet institutions in meeting middle level manpower needed in the labor market. to overcome challenges and to utilize market opportunities effectively, tvet institutions need to rely on strengthening labor market information system at institutional level. moreover, network and partnership program between tvet institutions and stakeholders need to be fostered in areas of job placement, work attachments, advice on courses, and donation of equipment, part-time teaching and financial assistance. furthermore, to utilize learning facilities such as experienced industrial experts, to reduce expenditures of laboratory equipment and to make trainees familiar with jobs in labor market, tvet institutions need to strengthen cooperative training with enterprises. acknowledgement i would like to express my deepest heartfelt appreciation and thanks to all sampled tvet institutions principals, process owners, department heads, tvet graduates, and employers of tvet graduates, and tvet office heads who contributed to the result of this research by making information easily accessible. references heyne,p. (1991): the economic way of thinking. new york; macmillan publishing company, p3447. ilo (2001): modernization in vocational education and training in the latin american and the caribbean region. geneva, ilo, p. 11. middleton, zinderman & adams (1993): skills for productivity. london, oxford university press, p. 114-117. moe (2008): national technical and vocational education and training (tvet) strategy. addis ababa, ethiopia, p.20-24. moe (2007): cooperative training framework addis ababa, ethiopia, p.21-29. niche (2010): niche strategy on tvet. netherlands, p. 3-5. osborne, d. geebler, t. (1992): reinventing government: how the entrepreneurial spirit is birhane sime ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 15 transforming the public sector. new york: penguins books, p. 23. unesco (2003): strengthening the industry linkages with tvet programs in arab countries through sectoral partnership. beirut, p. 112-114. unesco (2002): technical and vocational education and training for the 21 st century: new roles and ilo recommendations. paris, unesco/ilo, p.41-43. unesco (1973): technical and vocational teacher education and training. paris, unesco, p.115-117. ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 16 a causal analysis model of supply chain factors impacting operations efficiency mengist hailemariam and karuna jain indian institute of technology bombay, powai, mumbai-400076, india (e-mail: mengist@iitb.ac.in kjain@iitb.ac.in) abstract with the ever-increasing trend in customer expectations for better product and services, operations efficiency has been a concern for industries. the key strategy to improve operations efficiency (oe) lies in managing supply chain (sc) efficiently. there are many factors which are critical for a successful supply chain management (scm). the causal relationship between the factors largely influences operations decision. thus, there arises a challenge on how to establish causal relationship between factors. to resolve this, in this research we propose a decision making trial and evaluation laboratory (dematel) method since the current approaches are based on human judgments which are not simple to estimate. the application of the proposed method is illustrated in the airport operations context involving survey of practitioners and experts. data were analyzed using matlab program. findings reveal that in order to enhance oe decision makers need to consider the most important sc factors, the factors in the cause groups, and their influence level upon other factors. the study provides insight to decision makers on how to establish the cause effect relationship of factors quantitatively and convert into a visual structure map leading to a better operations decision. key words: operations efficiency, scm, airport operations, causal relationship, dematel introduction industries are facing tremendous challenges in today’s changing business environment due to everincreasing trend in customer expectations for better product and services. the key to address these challenges lies in the strategies followed and capability developed. scm capability is one of such capabilities that are required to enhance oe. scm is the process of integrating a network of intraand inter-organizations activities and key business processes to improve the flow of goods, services, finances, and/or information from suppliers to end customers (chow et al., 2008). excellent theoretical insights are found in literature on manufacturing and service industries unfolding operations and financial benefits realized through scm (lai and cheng, 2003). there is an increasing interest on implementing efficient scm strategies in many industries (li et al., 2006). airport industry as a service system requires multiple organizations and their relationship to successfully carry out its daily operations that can be achieved through scm. some key critical factors reported in the literature for successful scm implementation are mailto:mengist@iitb.ac.in mailto:kjain@iitb.ac.in mengist hailemariam and karuna jain ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 17 management commitment and information sharing (tummala et al., 2006), infrastructure and technology (fawcett et al., 2011), know-how (chow et al., 2008), performance monitoring (chan et al., 2006), and process improvement (li et al., 2006). industries have to prioritize implementation of the factors based on the influence of each factor over another factor and their importance to the operations. while the causal relationship among the factors largely influences implementation decisions, establishing causal relationship among factors is a challenge to decisions makers. to resolve this, decision makers use their judgments which are not simple to estimate. moreover, sufficient analysis of the relationship among the sc factors is not well addressed in literature. the purpose of the present study is three fold. first, to identify sc factors reported in literature those affect airport operations. second, to examine the relationships among these factors and the influence levels of each factor over other factors as well as their priorities applying dematel method. finally, to develop a structural model of the relationship to enable decision makers to take a better operations decision. this paper is organized as follows: section 2 explains the study framework and outlines the steps of dematel method. section 3, results and discussion of findings are presented. in section 4, conclusion of the study is presented. infrastructure (f2), technology (f3), and information sharing (f4), know-how (f5), performance monitoring (f6), and process improvement (f7). the study analyzes the causal relationship among these factors and finds the impact level of each factor over other factors. the dematel method is used to achieve this because it is a practical method for visualizing the structure of complex causal relationships with matrices and graphs (warfield, 1976). the method has been used in different areas of research and practices, such as in scm (amiria et al., 2011), safety management (liou et al., 2008), auto industry (wu and tsai, 2011), service quality (tseng, 2009), and technology (lee et al., 2010). this study uses practitioners and experts survey/interview to collect data. seven practitioners from one of the indian airports and three experts from academia who have operations and scm expertise, designated by p1 to p10 are participated in the study conducted from march 2011 to april 2011. each practitioner and expert was asked to indicate the degree of which he/she believes factor i affects factor j. the pair-wise comparisons to evaluate the influence and direction between two factors were denoted by aij and given an integer score 0 to 4 ranging from “no influence” to “very high influence'' respectively. in applying dematel method first, causal relation diagrams which capture the relationships between the seven factors are developed. mengist hailemariam and karuna jain ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 18 materials and methods seven sc factors that an airport should possess for enhanced airport operations are identified from the literature. these are management commitment (f1), based on this, an initial direct-relation matrix, a n x n matrix a for each of the causal relation diagrams is generated. the matrix a= [aij] shows the degree of direct impact each factor i exerts on each factor j. following this, the initial direct-relation matrix for n matrices is obtained using the equation: an= p1 + p2 + … + pn (1) then, the normalized initial direct-relation matrix n is computed by the following equation: n = an * (i, j = 1, 7..) (2) next, the total-relation matrix (t) is calculated by accumulating the normalized initial direct-relation matrix n as follows, where i is identity matrix. t = n (i – n) –1 (3) using equation (4) to (6), the sum of rows (di) and the sum of columns (rj) are calculated from t for each factor and a causal relation diagram is developed to explain the structural relation among the factors. t = n x n (i, j = 1, 2, ..., n) (4) (5) computing (di rj) gives the factor’s category into a cause group (di rj > 0) and effect group (di rj < 0). the causal relationship diagram which provides insight for making decisions can be mapped using the dataset of (di + rj, di – rj). by means of this diagram and the position of factors, a decision maker can identify whether a factor is a cause or an effect and how it is affected or affect others. results and discussion ten causal relationship diagrams have been developed by the ten practitioners and experts following the guidelines proposed by sterman (2000). since there are seven factors, ten 7 x 7 directrelation matrices were formulated for the ten causal relation diagrams. the initial direct-relation for the causal relationship diagram developed by one of the practitioners (p1) is given in table 1. each number in the matrix (aij=1) shows that there is a positive relationship between the two factors (i and j). table 1: the initial direct-relation matrix developed by p1 (6) matlab program is used to compute the relationship matrices and the degree of influence of factors. accordingly, the relative importance each of factors f1 f2 f3 f4 f5 f6 f7 f1 0 0 0 1 0 0 1 f2 0 0 1 0 0 0 0 f3 0 0 0 1 0 0 0 f4 0 0 0 0 0 1 1 f5 1 0 0 1 0 0 0 f6 0 0 0 0 0 0 1 f7 0 0 0 0 0 0 0 mengist hailemariam and karuna jain ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 19 the factors or the strength of influence both dispatched and received is determined by (di + rj). similarly, nine causal relationship diagrams have been developed by the remaining nine practitioners and experts and their corresponding initial directrelation matrix were formulated accordingly. the initial direct-relation matrix determined by accumulating the ten matrices of the ten diagrams using equation (1) is shown in table 2. table 2: the initial direct-relation matrix for sc factors factors f1 f2 f3 f4 f5 f6 f7 f1 0 1 2 3 2 2 3 f2 1 0 4 3 3 2 2 f3 1 3 0 4 2 1 4 f4 0 0 1 0 2 3 3 f5 4 0 1 3 0 3 4 f6 2 0 0 1 3 0 4 f7 1 1 0 3 0 1 0 the initial direct-relation matrix given in table 2 is normalized using equation (2) and results are reported in table 3. the total-relation matrix is calculated from table 3 using formula (3). table 3: the normalized direct-relation matrix for sc factors factors f1 f2 f3 f4 f5 f6 f7 f1 0.000 0.209 0.417 0.626 0.417 0.417 0.626 f2 0.209 0.000 0.834 0.626 0.626 0.417 0.417 f3 0.209 0.626 0.000 0.834 0.417 0.209 0.834 f4 0.000 0.000 0.209 0.000 0.417 0.626 0.626 f5 0.834 0.000 0.209 0.626 0.000 0.626 0.834 f6 0.417 0.000 0.000 0.209 0.626 0.000 0.834 f7 0.209 0.209 0.000 0.626 0.000 0.209 0.000 the key decision factors and relationships can be obtained from the total-relation matrix. the di and rj are also calculated as shown in table 4. table 4: the total-relation matrix for sc factors factors f1 f2 f3 f4 f5 f6 f7 di f1 0 0.0008 0.0016 0.0025 0.0016 0.0017 0.0025 0.0107 f2 0.0008 0 0.0033 0.0025 0.0025 0.0017 0.0017 0.0125 f3 0.0008 0.0025 0 0.0033 0.0017 0.0008 0.0033 0.0124 f4 0 0 0.0008 0 0.0016 0.0025 0.0025 0.0074 f5 0.0033 0 0.0008 0.0025 0 0.0025 0.0033 0.0124 f6 0.0016 0 0 0.0008 0.0025 0 0.0033 0.0082 f7 0.0008 0.0008 0 0.0025 0 0.0008 0 0.0049 mengist hailemariam and karuna jain ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 20 rj 0.0073 0.0041 0.0065 0.0141 0.0099 0.0100 0.0166 the relative importance the factor has (di + rj) and the factor relation (di rj), i.e, the net effect the factor contributes to the system are calculated using equation (4) to (6) and the results are reported in table 5. table 5: the degree of influence of sc factors f1 f2 f3 f4 f5 f6 f7 di + rj 0.0180 0.0166 0.0189 0.0215 0.0223 0.0182 0.0215 di rj 0.0034 0.0084 0.0059 -0.0067 0.0025 -0.0018 -0.0117 using (di rj) values, we identified the cause group (di rj > 0) & an effect group (di rj < 0). this relationship is transformed by the proposed dematel method and mapped in figure 2. figure 2: the causal diagram using the t values given in table 4, the interdependencies among the identified cause and effect group factors and their strengths are illustrated in figure 3. mengist hailemariam and karuna jain ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 21 f2. infrastructure f3. technology f4. information sharing f5. know-how f6. performance monitoring f7. process improvement f1. management commitment figure 3: interdependencies among sc factors we have established a threshold to group the t values and represented with different lines for ease of understanding. the thresholds are tij > 0.3 (higher influence, thicker lines), 0.25 ≤ tij < 0.3 (high influence, thin lines), 0.15 ≤ tij < 0.25 (medium influence, dotted lines) and tij < 0.1 (low influence). to reduce the complexity of the figure, low influence factors are omitted. factors with several arrows mean that each factor shows a frequent interactive relation with other factors. based on the results, valuable insight and several implications can be generated for decision makers in the airport operations. 1. referring to (di + rj) values in table 5, among the seven factors, f5 and f4 are the most critical factors by numerical figures (0.0223 and 0.0215, respectively) to be taken into account. this finding matches with the finding exhibited in figure 3 that these factors are with the highest number of interactive arrows indicating their strength and influence on other factors. prioritizing of these factors follows f5>f4>f7>f3>f6>f1>f2. hence, the key to airport oe is building scm know-how (chow et al., 2008) followed by information sharing. 2. the findings from figure 2 indicates that four factors: f1, f2, f3 and f5 are defined as cause factors, while the other three, f4, f6, and f7 are in the effect group. the cause factors dispatch the influence to other factors more than they receive whereas, effect factors receive the influence from other factors more than they dispatch. recognizing the difference between cause and effect factors help decision makers take proper operations decisions (amiria et al., 2011). 3. the decision makers have to concentrate on improving the cause factors as these are influencing factors having positive impact to get high performances in terms of effect factors. in other words, the effect factors: f4, f6, and f7 can be improved through management commitment, availability of infrastructure, implementing technology, and building know-how through training and development. ultimately, this enhances the oe. conclusion enhancing oe is a must for the success of industries which is affected by many issues such as effective management of the sc. this context is very critical mengist hailemariam and karuna jain ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 22 for airport industry because of the dynamic and complex nature of the airport business environment. in order to facilitate decision making on implementation of the sc factors leading to enhanced oe, airports are required to understand the causal relationship among the factors. in this paper, we have investigated the complex relationship between factors impacting airport oe quantitatively and developed a structural model of the relationship using the proposed dematel method since the current approaches are based on human judgments which are not simple to estimate. the proposed approach can be modified as required for analyzing operations and scm issues of other industries. the results reveal that scm know-how is the most important factor as well as a cause factor to enhance oe. further, airport industries need to pay more attention to the identified four cause factors to drive performance in the effect factors and achieve operational success. this understanding could help practitioners in their effort for successful sc process implementation. acknowledgements the authors would like to acknowledge the practitioners and experts for sharing their thoughts and ideas relevant to the study. we are also grateful for the constructive suggestions of the editor-inchief. references amiria, m., sadaghiyani, j.s., payani, n. and shafieezadeh, m. 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(2011): a dematel method to evaluate the causal relations among the criteria in auto spare parts industry. applied mathematics and computation, in press, corrected proof, available online 3 august 2011. economic efficiency of export–oriented cattle-fattening farms in east shewa zone: the case of adama city and its surroundings oumer berisso department of economics, school of business and economics, adama science and technology university p.o. box 1888, adama, ethiopia. e-mail: ub_ansha@yahoo.com abstract this study was undertaken to measure the economic efficiency of export–oriented cattle-fattening farms in adama city and its surroundings and to identify their determinants. technical, allocative and economic efficiencies were estimated by a non-parametric data envelopment analysis (dea) method and the identification of their determinants using tobit model. the study result showed the existence of substantial inefficiencies in production as well as efficiency differentials among the farms. the mean technical, allocative and economic efficiencies were found to be 88%, 62% and 55%, respectively. an econometric analysis based on tobit model indicated that length of fattening period had significant negative impact on all efficiency scores, whereas training and schooling had significant positive impact on allocative and economic efficiencies. farm head’s year of experience on cattlefattening, extension contact and off farm income had significant positive impact on technical efficiency. experience sharing program, year of experience and feeding frequency has significant positive impact on economic efficiency. policy measures aimed at developing better farm-level training programs focusing on the fattening period, feeding mailto:ub_ansha@yahoo.com ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 24 and management record keeping; enhancing farms’ access to information, and marketing systems are recommendations drawn from the study to increase productive efficiency of cattle fattening farms in the study area. key words: dea, tobit analysis, cattlefattening farms, technical, allocative, economic, efficiencies. introduction like most sub-saharan african countries, ethiopian economy is heavily reliant on agriculture and allied economic activities. this is because agriculture adds 47% to the total gdp, provides livelihood to more than 80% of the population, constitutes nearly 90% of the nation’s total export and makes most of the exchange earnings to the economy (csa, 2007). when we take the livestock subsector, ethiopia ranks first in africa and tenth in the world with respect to livestock population. it is estimated at around 35 million tropical livestock units (tlu), which includes 30 million heads of cattle, 42 million heads of sheep and goats, about 7 million equines, one million camels, over 53 million chickens, 10 million bee colonies, and 40 thousand ton annual harvestable fish (azage et al., 2009) in the country. livestock production contributes an estimated 16 % to the total gdp and over 40 % to the agricultural gdp (diao et al., 2007), 15% of export earnings and 30% of agricultural employment (staal et al., 2008). the subsector is the second major source of foreign currency oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 25 through export of live animals, hides and skins (ilri, 2003). the sector also employs about one-third of the country’s rural population (ilri, 2003). the recent economic policy of the government of ethiopia under growth and transformation plan (medaf, 2011) places a great emphasis on commercialization of agriculture, diversification of production and exports, and private sector investment in order to move farmers beyond subsistence farming to small-scale market-oriented agriculture. nevertheless, the agricultural service delivery system in general and livestock service in particular which were implemented in the past did not lead to the envisaged commercialization of agricultural producers. hence, with the process of commercialization of the country’s subsistence-oriented production systems to more productive and market-oriented production systems, the agricultural support service has to be transformed and should become responsive and innovative. on the other hand, despite the fact that agriculture is primarily a rural based activity in ethiopia, the phenomenon of urban and peri-urban agriculture (upa) is also becoming evident. there is large population of agricultural producers with in urban and peri-urban areas. now a days, market oriented livestock production systems are one of upa emerging and dominating most urban centers in the country, varying in kinds and levels. the systems involve the production, processing and marketing of milk and milk products, animal breeding and cattle fattening farm productions. addis ababa and bushoftu cities and their surroundings are one of the areas that exhibit market oriented dairy production. adama city and its surrounding towns are also well known by its cattle fattening farms as a major market –oriented, especially export -oriented livestock production activity. thus given the current and previous governments’ economic policies that aim at improving farm productivity; productivity and market performance of market oriented livestock production with export potential, detailed and systematic empirical studies on the production efficiency of market oriented livestock production in ethiopia are scarce or non-existent, particularly of exportoriented. accordingly this research has been conducted to assess farm level technical, allocative and economic efficiencies of export-oriented cattlefattening farms and its confounding factors in adama city and its surroundings. materials and methods the data used for this study were collected both from primary and secondary sources. the primary data were collected from heads of sample farms through formal farm survey using structured questionnaire;interviews ,field observations & focus groups discussion and finally triangulated to each other. the content of the questionnaire was mainly emphasized on personal characteristics of farmers, farm characteristics, and access to institutions. before embarking on the actual survey, a pre-test of the questionnaire was conducted in order to identify difficult or unwanted questions, to see the reaction of the respondents to the questions, and to check the appropriateness of the questionnaire. to generate primary data for the research a two stage cluster random sampling technique was used to select a sample of respondents. first, a total list of exportoriented cattle-fattening farms was obtained after stratifying them into two groups, namely, urban, and peri-urban feedlots. secondly, a list of` the sample oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 26 respondent of cattle-fattening farms who has bulls in their feedlots during the survey period was prepared randomly from both lists. accordingly the total sample size for the study was 62 cattle-fattening farms that are selected randomly from a total population of 95 cattle-fattening farms in the study area, which has bulls in their feedlots during the survey period. for data analysis, descriptive method, which included frequency distributions, maximum, minimum, percentages, measures of central tendencies and measures of dispersion of the sample units, were used to describe some important characteristics of the sampled farms; a mathematical (linear) programming method called dea was used to estimate efficiency of production and an econometric method called tobit was used to identify factors affecting the efficiency of production. the model the models used in the study were a two-stage approach involving dea and tobit models. in this approach, a dea problem were solved in the first stage using general algebraic modelling system (gams) and at the second stage, the efficiency scores from the first stage were regressed upon different explanatory variables using tobit model. hence, under dea frontier, we used the model specified by equation (1) and solved the same linear programming problem (charnes et al., 1978) for the i th farm or for each dmusi , i = 1, 2,..., n; and obtain the technical efficiency (tei) score  for each of the n dmus in the sample. 0 0 0. min ,         xx yyts i i (1) like wise, in order to derive a measure of total economic efficiency (ee) index, the model specified by equation (2) were used and solved the same inputbased cost minimization dea model. 0 0 0. min * , *         xx yyts xw i i x i t i i (2) then the total or overall economic efficiency (eei) index for the i th firm is computed as the ratio of the minimum cost to the observed cost given input prices and crs technology (coelli et al., 2005), given by equation : (3) allocative efficiency (aei) of the i th firm is then the ratio of economic efficiency and technical efficiency of the i th firm. for the inefficiency factors the tobit model (tobin, 1958), was specified as:             1 11 1 ii i i n j ijji eife eif e xe  (4) where i refers to the i-th farm in the sample; xj represents various farm-specific variables; βj are parameters to be estimated; ηi is the error term and i   ),0( 2  n ; ei is an efficiency measure representing technical or allocative or economic x i t iw x iw t i eei *  oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 27 efficiency and ei * is the latent variable, with    iii xxee   . description of the model variables input-output variables for dea models output variable: yield or the output variable(y) in the production function for this study is a yield per farm which is defined as the actual quantity of the output (the total sum of live weight of all bulls in the feedlot) produced per farm during the survey period, measured in kilograms. production inputs for dea model:-the quantity and qualities of the inputs and technical skills of the farmer to use the inputs properly determines production or efficiency of the farm producers. thus, for this study, six inputs such as labor(in hours), number of bulls(in head), total quantity of concentrate feed (quintal), total quantity of roughage feed (quintal), length of fattening periods(in days), costs of veterinary and medicine (in birr) were specified as production inputs and were used in the production functions (equations). variables for tobit model the dependent variable for the tobit model: are the technical, allocative and economic efficiency estimates derived from dea frontier models in the production functions. independent variables for inefficiency factors: after economic efficiencies are estimated for each farm, sources of inefficiency differential among farm, besides input constraints, were estimated using efficiency scores as dependent variable, using tobit analysis. for this purpose twelve explanatory variables were used for inefficiency model for this study, and were categorized in three groups as follows: demographic factors: these include personal characteristics of farm head such as age, education and cattle fatting farm experience of the farm heads. socioeconomic factors: these are farm characteristics such as farm size (number of bulls), length of fattening period, daily feeding frequency, off/non-farm employment and existing management record. institutional factors: these include access to institutions such as, use of credit, extension service, training of the farm head on cattle-fattening farm and their participation on experience sharing programs. results and discussion descriptive results descriptive statistics were used to analyze primary data. accordingly the summery of descriptive analysis of the output and input variables used in the non-parametric dea models and of the explanatory variables used in tobit model are presented below. descriptive analysis of the output and input variables for the dea models as can be observed from table 1 below, the descriptive statistics result showed that the sample cattle-fattening farms produced 72.9 tons of live http://medwelljournals.com/fulltext/?doi=javaa.2010.60.69#t2 oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 28 weight, on average. the minimum was 17.2 tons and the maximum was 220 tons. table 1: descriptive statistics of the output and input variables used in the dea model variables mean std. dev. min max output live weight (kg) 72921.98 44651.72 17166.00 220350.00 inputs number of bulls (head) 195.02 118.14 50.00 600.00 labor (man-day-hrs) 3376.26 2689.45 528.00 14400.00 fattening period (days) 66.73 33.45 15.00 150.00 total concentrate feed (quintals) 1291.05 943.17 117.00 3900.00 total roughage feed (quintals) 758.84 613.01 104.00 2625.00 costs of veterinary and medicine (birr) 4427.32 3658.44 1000.00 18000.00 to reach the present level of production, cattlefattening farms used approximately 3376 labour hours, 205 tons of total feed, of which 129.1 tons is concentrate (by-product) feed and 75.9 tons is roughage feed on average. in addition to these inputs, farms expenses 4427 birr for veterinary and medical costs on average during the fattening period. the sampled farms kept their bulls on average for 67 days in the feedlots. the average feed intake per animal during the fattening period was 1051.12 kg, with concentrate feed 662 kg and roughages 389.11 kg. daily feed intake per animal during the fattening period was 15.75kg with concentrate feed 9.92 kg and roughages of 5.83 kg. the farms were obtained a bull weighing a live weight of 373.92 kg on average during the fattening period. thus the farmers were producing on average above the country’s minimum requirement of live weight of bulls to export from the country during the fattening period; as the live weight average is 373.92 kg in the study area while the minimum national value to export from a country is 325 kg. descriptive analysis for explanatory variables used in tobit model as can be observed from table 2, for the sampled farms, the average age of the farm heads at the time of the survey was 42 years with the minimum and maximum 22 and 65 years, respectively. furthermore, when we see the age of the farm heads in age range; 2 (3.2%) of them are less than 31 years old, 30 (48.4%) of them are in between 31-40 age, 25 (40.3%) of them are between age of 41-55, and only 5 (8.1) of them are more than 56 years old. this indicates most of the producers are young. when we see the year of farm head experience of the sampled farms on cattle-fattening farm or/and similar activities, the sampled respondent farm heads had an average of 7.65 years of farm experiences that ranges from 1 year to 18 years of farm experience. oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 29 table 2: summary of descriptive statistics of explanatory variables used in tobit model demographic characteristics as shown table 3 above, majority of the sample respondents, that is 53 (85.5%) had attended at least elementary school education out of which 11 (17.7%) had completed primary education, 1-6; 29 (46.8%) table 3: educational level of the sample respondents completed junior and secondary education, 7-12; 8 (12.9%) had graduated with diploma or certificate and 5 (8.10%) had b.a/b.sc degree qualification. meanwhile, 9 (14.5%) of the sampled producers were illiterate. socio economic characteristics only about 29 (47%) of the sampled farm head reported to earn off/non-farm income from non-cattle fattening farm activities. about 48 (77.4%) the sampled farm had management records. regarding feeding frequency, the majority of them, that is, 56(90.3%) farmers feed their bulls twice per day and only 6(9.7%) of the farmers reported that they feed their cattle three times daily. institutional characteristics a total of 47(75.8%) of the sampled farms reported contact with extension agents but have very few contacts with extension services in a month, only (1.6 times on average, or 1-4 times per month). exactly half of the sampled farms had access to credit of which 25(40.3%) used formal credit institutions, while 6(9.7%) have used informal credit sources either from relatives, friends or local money lenders. credit use averaged approximately 365806.5 birr per farm. about 38(61.3%) of the sampled producers have access to training on cattle-fattening farm variables continuous variables dummy variables mean std. dev. min max percentage of farmers with dummy = 1 percentage of farmers with dummy = 0 schooling (years) 7.68 4.78 0 16 age (years) 42.35 8.91 22 65 farm experience (years) 7.65 4.42 1 18 farm size (no. of bulls 195.02 118.14 50 600 fattening period (days) 66.73 33.45 15 150 extension contact (number) 1.60 1.20 0 4 credit amount (birr) 365806.5 547496.7 0 3000000 feeding frequency (no. of times) 2.10 0.30 access to training (yes/no) 0.61 0.49 61 39 experience sharing (yes/no) 0.29 0.46 29 71 management records (yes/no) 0.77 0.42 77 23 off/non-farm (yes/no) 0.47 0.50 47 53 education level frequency percentage illiterate 9 14.5 primary 11 17.7 secondary 29 46.8 diploma 8 12.9 ba/bsc 5 8.10 oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 30 system and 18 (29%) of them have obtained experience sharing out of ethiopia. dea and econometric model results a. technical efficiency analysis: the results derived from dea models as shown in table 4 indicated that technical efficiency indices differed substantially among farms, ranging from 0.34 to 1.00 with 19 fully efficient farms out of the 62 sampled farms with an average efficiency score of 0.88. table 4: distribution of technical, allocative and economic efficiencies of sample farms (n = 62) an average efficiency score of 0.88 implies that if the average farm in the sample was to achieve the technical efficiency level of its most efficient counterpart, then the average farm could realize a 12 % input reduction. a similar calculation for the most technically inefficient farm revealed input saving of 66 %. though the maximum and the minimum technical efficiency scores differed considerably, the modal technical efficiency class is 0.91-1.00, representing 46.8 of the sample producers indicating that the highest number of farmers had technical efficiencies between 0.90 – 1.00. of the sample farms, 79% had a higher technical efficiency scores than the mean technical efficiency. this implies that the farms are fairly technically efficient. b. allocatve efficiency analysis the estimated allocate efficiencies differed substantially among the farms ranging between 0.31 and 1.00 with the mean allocative efficiency of 0.62. this implies that if the average farm in the sample was to achieve allocative efficiency level of its most efficient counterpart, then the average farm could realize 38 % cost saving. a similar calculation for the most allocatively inefficient farm revealed cost saving of 69 %. the frequency of occurrence of the estimated allocative efficiencies in deciles ranges indicate that a clustering of allocative efficiencies in efficiency (%) frequency percentage te ae ee te ae ee 0 – 10 0 0 0 0 0 0 11 – 20 0 0 1 0 0 1.6 21 – 30 0 0 2 0 0 3.2 31 -40 1 4 4 1.6 6.5 6.5 41 -50 0 3 13 0 4.8 21.0 51 -60 0 17 24 0 27.4 38.7 61 -70 2 29 14 3.2 46.8 22.6 71 -80 10 8 3 16.1 12.8 4.8 81 -90 20 0 0 32.3 0 0 91-100 29 1 1 46.8 1.6 1.6 total 62 62 62 100 100 100 mean 88 62 55 std. deviation 12.038 10.978 13.353 minimum 34 31 20 maximum 100 100 100 oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 31 the region of 0.61-0.70 efficiencies range representing 46.8 % of the respondents. c. economic efficiency analysis: the combined effect of technical and allocative efficiency results showed that the average economic efficiency level for the sample farms is 0.55, with a lowest of 0.20 and a highest of 1.00. this indicated the existence of substantial economic inefficiencies of production in the study area. however, low economic efficiency scores revealed that there was a considerable room to increase agricultural output without additional inputs, given the existing technology. if these farms operated at full efficiency levels, they could reduce, on average, their costs of production by 45 % and still produce the same level of output. tobit estimates: analysis of determinants of efficiency econometric analysis the tobit results (table 5) showed that, except credit amount and length of the fattening period, all explanatory variables had a positive relationship with technical efficiencies tobit analysis was used to explain efficiency differentials among the sampled farms. before undertaking tobit model estimation and making an econometric analysis, the explanatory variables were checked for their multicollinearity using different batteries of tests. to test existence of multicollinearity in the hypothesized explanatory variables, vif and tol was computed. the results showed that the entire explanatory variables had no serious multicollinearity problem. furthermore, for hetroscedasticty test, we used a hetroscedasticy robust method; robust standard errors are often reported in applied cross-sectional work, especially when there is heteroskedasticity problem (jeffrey, 2002). finally, tobit estimation was conducted by stata. table 5: factors affecting efficiency of exported-oriented cattle fattening farms in the study area variables te ae ee coefficient (std error) marginal effect coefficient (std error) marginal effect coefficient (std error) marginal effect intercept 0.656(0.198)*** 0.919 0.535(0.125) *** 0.617 0.316(0.137)*** 0.552 agefh 0.002(0.002) 0.002 0.001(0.001) 0.001 0.001(.002) 0.002 crtamount -1.020(4.56) ** -1.02 -7.510(2.84) *** -7.51 -1.280(3.12) *** -1.28 expsharing -0.008(0.052) -0.009 0.037(0.032) 0.038 0.057(0.035)* 0.057 feedingfrqu 0.039(0.063) 0.039 0.054 (0.041) 0.054 0.087(0.045) ** 0.088 yexpr 0.008(0.004)* 0.008 0.001(0.003) 0.001 0.005(0.003)* 0.006 flength -0.001(0.000)*** -0.002 -0.001(0.0004)*** -0.002 -0.001(0.0004)*** -0.002 mgtrecords 0.033(0.052) 0.033 -0.045(0.033) -0.045 -0.032(.037) -0.033 farmsiz 0.0001(0.0002) 0.0001 0.0001(0.0001) 0.0001 0.0001(0.0001) 0.0002 off-farm 0.087(0.048)*** 0.087 -0.002(0.029) -0.002 0.034(.032) 0.034 schooling 0.004(0.005) 0.005 0.006(0.003)** 0.006 0.007(0.003)** 0.007 training 0.038(0.041) 0.039 0.042(0.026)* 0.043 0.061(0.029)** 0.062 extcontactm 0.024(0.016)* 0.025 -0.015(0.009) -0.015 0.008(.011) -0.009 oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 32 *** significant at 1% level; **significant at 5% level;* significant at 10% level. the significant positive relationship of off/non-farm income with technical efficiency might be explained by the fact that off/non-farm employment may absorb under-employed labour resources, improve the experience and human capital of the farm operator and bring additional income that could be used for funding farm activities, thus leading to a positive relationship with technical efficiency. most of contacts with extension services were associated with greater technical efficiency. thus extension visits were found to positively and significantly affect technical efficiency for this study. similar results were reported by kaliba, a.r and c.r engle, (2006). schooling is positively and significantly related to allocative and economic efficiencies, which confirms with previous studies by coelli et al. (2002), and this result may be explained by the fact that education is expected to make farm head less conservative and more receptive to new technology and innovation, which will consequently lead to higher efficiencies. moreover, this result may be explained by the better education level of the sampled farm head as about 86 % of the sampled farm head have at least completed primary education thus resulted in positive efficiency relations. feeding frequency is positively and significantly related to economic efficiency, which indicated that farms with higher feeding frequency were more economically efficient than farms with lower feeding frequency, as expected. similar results were reported from previous studies (ceyhan and hazneci, 2 0 1 0 and ghorbani et al., 2009). another outcome of the tobit model was the significant effect of credit use on economic efficiency. although 31 (50%) of the sampled farms had access to credit from either formal or informal credit sources, credit use showed unexpected negative sign on technical, allocative and economic efficiencies level significantly. as a result, farms using more credit were more inefficient. this may be due to shortage of working capital, due to high input costs and low returns on outputs, together with high credit costs, the moral hazard problem of credit and ‘fungibility of loan’ (or loan diversion). training had significant positive impact on allocative and economic efficiencies. similar results were reported from previous studies (ceyhan and hazneci, 2 0 1 0 ). the result verifies the importance of capacity building and technical assistance for agriculture entrepreneurs and producers to improve production efficiency. farm experience in cattle-fattening had a significant positive impact on technical and economic efficiencies. this is because most of the sampled farm heads were experienced farmers (with average 7.65 years of cattle fatting farm experience) and as most of farms are own operated, daily works of farms were done by themselves, and thus resulted in a positive influence on technical and economic efficiencies among the farms. the result was in line with the findings of mbanasor and kalu (2008). experience sharing program was found to significantly and positively affect economic sigma 0.127 (.015) 0.086(0.008) 0.094(0.008) lr χ 2 (12) 28.10 *** 31.46*** 43.80*** log likelihood 14.625 61.708 55.960 http://scialert.net/asci/author.php?author=vedat&last=ceyhan http://scialert.net/asci/author.php?author=kerem&last=hazneci http://scialert.net/asci/author.php?author=vedat&last=ceyhan http://scialert.net/asci/author.php?author=kerem&last=hazneci http://scialert.net/asci/author.php?author=kerem&last=hazneci oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 33 efficiency as hypothesized. the positive relationship of experience sharing activity with efficiency magnifies the role of experience sharing program as one capacity building programmes in addition to training and extension service as technology adoption can be acquired through observation also. in fact, 18 (29%) of the sampled farmers have obtained experience sharing programs out of ethiopia to some african and meddle east countries. length of fattening period was found to be significantly and negatively affect all efficiencies. this result is in line with ghorbani et al. (2009). the negative relationship of length of fattening period with all efficiencies may be is due to the extended period of fattening period length as few of the sampled farms kept their bulls for more than three months, which in tern resulted in loss of live weight of bulls, loss of the standard quality of beef for export and incurs to more unnecessary feed costs and thus resulted in the negative relationships with all efficiencies. conclusion and recommendations conclusion this study evaluated economic efficiency of exportoriented cattle fattening farms in adama city and its surroundings and identified their determinants, using dea and tobit models respectively. using a detailed survey, data were collected in the production year of 2010 from june to july, form 62 sampled cattle fattening farms and measures of technical, allocative and economic efficiencies were obtained. the results indicated that the mean technical, allocative and economic efficiencies were 88%, 62% and 55%, respectively. this indicated the existence of a substantial allocative and economic inefficiencies as well as variations in efficiency levels among farms. dea results showed that the excess cost owing to inefficiency of the sample farms in the study areas was, on average, 45% and was mainly due to allocative inefficiency. tobit result showed that length of the fattening period and credit amount had significant impacts on all efficiency scores, whereas training and schooling had significant impact on allocative and economic efficiencies. extension contact, farm head year of experience and off/nonfarm income had a significant impact on technical efficiency. farm head year of experience, experience sharing and feeding frequency had a significant impact on economic efficiencies. recommendations policy implications of this analysis are that efficiency estimates indicate both the distribution of the farms’ efficiency and its institutional and socioeconomic determinants. an analysis of the determinants’ relative efficiency indicates which aspects of the farms’ human and physical resources must be targeted by public investments to improve farm efficiency. that means the identification of those factors contributing to efficiency differentials among farms might help to formulate better policy for intervention. result from inefficiency differentials suggests that policy-makers should focus on these institutional and socio-economic factors influencing efficiency of production. they should focus on enhancing farms’ access to information via better extension services, marketing systems and encouraging management record keepings. capacity building and technical assistance for agriculture producers is important to improve production efficiency. thus training, agricultural extension and other capacity building programs for farms should be provided to improve the economic efficiency of oumer berisso ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 34 individual farms up to at least the level of the best cattle-fattening farms. hence training focusing on the fattening period, feeding and management record keepings are the major recommendation drown from the study to enhance production efficiency of cattle fattening farms in the study area. references azage tegegne, berhanu gebremedihin, dirk hoekstra and nigatu alemayehu (2009): rural urban linkage in market-oriented dairy development in ethiopia: lessons from the ada’a dairy cooperative. addis ababa, ethiopia binswanger, h. and rosenzweig, m. 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(1958): estimation of relationships for limited dependent variables. econometrica, 26: 24– 36. ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 36 a comparative study of occupational role stressors among academic officers of private and public higher educational institutions in oromia regional state of ethiopia kassim kimo school of pedagogy, adama science and technology university e-mail: amuda2008@gmail.com abstract this study aimed to examine occupational role stressors among academic officers of public and private higher educational institutions in oromia regional state of ethiopia. to address this, a total of 251 academic officers were selected using random sampling techniques from higher educational institutions in the state. data were collected from participants using a questionnaire focusing on occupational role stress questionnaire. the findings of the study indicated that there were significant mean differences in all role stressors (i.e., role overload, role insufficiency, role ambiguity & role boundary) between public and private educational institutions, in which the mean scores for academic officers of public institutions were higher than that of private institutions. based on the findings of the study some recommendations were suggested. key words: academic officers, role stressors, public & private higher educational institutions introduction in the pursuit for organizational excellence, managers of all types of organizations are forced to work under highly stressful circumstances. in those situations, managers are likely to undergo reduced psychological well-being. stressfulness of their working conditions may induce stress-related health problems. according to shanfa, et al. (1998), regardless of the types of organizations, managers tend to experience more stress from every source of pressure than their subordinates. they appeared to suffer from mental strains and anxiety as they have to face various organizational problems (pestonjee, 1999; assadi, 2003). in this regard, job related stress among managers has been acknowledged as reaching an epidemic level (francis, 2007, lindorff, 1994). differences in the experiences of work stress were also highlighted between public and private sectors. for instance, in south australia; public sector ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 37 workers have more stress claims than private sector workers; the average duration and cost per claim is higher than for the public sector (dollard, 2001). besides, lu, et al. (2009) have also pointed out that managers were encountered higher levels of occupational stressors and psychological strain in private enterprises than those in state-owned enterprises. with regard to their incidences, studies revealed that heavy demands are stressful when they exist simultaneously with restricted control over one’s own life situations (karasek and theorell, 1990). people may experience stress and dissatisfaction when the role expectations embedded in one of their work roles differ, or contradict with other their work roles. besides, one may hold many roles at the same time, but the benefits from those roles decrease when the number of roles becomes too high. it could also be harder and more burdensome for managers in a hectic working environment to handle multiple tasks which may lead to role stress (nordenmark, 2004; spector, 2008). in such situations, there could be a possibility of high risk of mental strains, which in turn increases the risk of psychological illness. studies have also established the relationships between role stressors and the feeling of strains associated with various psychological and physiological reactions (fogarty, et al. 2000; peiro, gonzalez-roma, et al. 2001; posig & kickul, 2003; osipow, 1998; fako, 2010, idris, 2011). in those cases, role stressors (viz., role overload, role ambiguity, role boundary and role insufficiency) are likely threaten managers’ capability to accomplish assigned tasks. moreover, studies noted that role overload creates strain because of the pressure to do more work, having a heavy workload that interferes with work quality, and the feeling of not being able to finish a given task within a specified period of time (conley & woosley, 2000; greenberg, 1999; fako, 2010). in the case of role ambiguity, individuals experience strain when they consistently do not have a clear picture about their work objectives, their co-workers’ and supervisor’s expectations of them, and the scope and responsibilities of their jobs (spector, 2008; conner & douglas, 2005; fako, 2010; idris, 2011). role boundary also occurs when individuals are required to play two or more role requirements that work against each other which create expectations that may be hard to reconcile (spector, 2008; conner & douglas, 2005; rizzo, et al. 1970) and role insufficiency measures the extent to which the individual’s training, education, skills, and experience are appropriate to job requirements (osipow, 1998). as per the existing studies, there have been growing evidences that higher education no longer provide the stress free working conditions (winefield et al, 2003; barkhuizen and rothmann, 2008). occupational stress levels among academic staff of higher education are generally found to be high (michailidis, 2008; catano, et al. 2007; barkhuizen and rothmann, 2008; biron, et al. 2008), alarmingly widespread and increasing across the globe (gillespie et al, 2001). however, most of what have been known about stress among higher education employees are based on studies conducted in the united states, great britain, australia, canada and new zealand and other developed countries (adeyemo & ogunyemi, 2005; thorsen, 1996; tytherleigh et al, 2005) all cited in kassim kimo ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 38 fako (2010). in fact, studies on stress in higher educational institutions have also been done in africa (nhundu, 1999; ofoegbu and nwadiani, 2006) in fako (2010) and (2011). more specifically, such studies did not cover stress related to academic staffs that are in charge of office duties be it in public or private higher educational institutions. apparently, academic staff members with office duties in addition to teaching and research activities seem to be more stressed than those with academic duties alone. because, alike other managers in any organization, academic officers in higher educational institutions are also expected to perform managerial functions/ administrative issues. moreover, sandwiched between administration and instruction, academic officers are required to manage the frequently competing priorities, interests, agendas, and other matters of concern regardless of the types of institutions (public and private) of oromia regional state of ethiopia. in this regard, the responsibilities of complex and challenging positions tend generate stress as they are expected to respond to demands that generate even more stress. hence, to the best knowledge of the researcher, no studies have also been found that examined the extent to which academic officers of public and private higher educational institutions are confronted with role problems in oromia regional state of ethiopia. therefore, it is felt necessary to address the perceived role problems among academic officers of public and private higher educational institutions in the state. hence, the objective the study was to examine occupational role stressors among academic officers of public and private of higher educational institutions in oromia regional state of ethiopia. based on this, the researcher devised the following research questions to attain this objective. research questions  is there a significant difference in role overload between academic officers of public and private higher educational institutions?  is there a significant difference in role insufficiency between academic officers of public and private higher educational institutions?  is there a significant difference in role ambiguity between academic officers of public and private higher educational institutions?  is there a significant difference in role boundary between academic officers of public and private higher educational institutions? significance of the study the results of study will benefit stakeholders in higher educational institutions (e.g., mangers, experts, supervisors, researchers, policy makers) to understand role stressors and their corresponding effects on academic staff who have been holding office duties in addition to teaching and research activities in public and private higher educational institutions. in general, the results of this study are expected to contribute to the existing body of knowledge and also help to narrow down the gap of information with respect to occupational stress in public and private higher educational institutions. population, subjects, and sampling techniques the target population of the study were academic officers of public and private higher educational institutions in oromia regional state of ethiopia. the study was delimited to oromia regional state due to limited resources of the researcher for data kassim kimo ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 39 collection. the academic officers are academic staff with office duties in addition to teaching and research activities in their respective departments. these included department heads, deans, vice deans, registrars, research and publication officers, student deans, guidance and counselling officers, and other officers who have been in charge of office responsibilities. participants were selected using multistage sampling techniques from five public higher educational institutions (viz.; adama, wollega, jimma, haramaya and madda wolabu universities) and from accredited seven private higher educational institutions (kuyera adventist college; rift valley, africa beza, royal, admas, and central university colleges and unity university-adama branch) for the study. list of academic officers and relevant information was obtained from the department of human resource development of each higher educational institution under the study. a total of 251 academic officers were selected for the study and their demographic characteristics are presented in table 1. table1: demographic characteristics of participants demographic characteristics groups subcharacteristics freq. % min. max. mean std. deviation age(in years) 21 60 33.53 9.20 gender public male 143 57 female 11 4 total 61 private male 93 37 female 4 2 total 39 total 251 100 experience(in years) 1 35 10.73 8.85 educational status public graduate 34 13 post graduate 105 42 phd 15 6 total 61 private graduate 82 33 post graduate 15 6 phd total 39 total 251 100 tools of data collection occupational stress inventoryrevised (osi-r) (osipow, 1998) was used to collect data. because, osi-r theoretical model of stress hypothesizing that stressors originating in the work environment influence how individuals perceive their work roles; that when work stressors interact with stress-inducing work roles, personal or psychological strain results. this questionnaire has three components to measure the three domains: occupational role stress, personal strain, and personal resource for coping. since this study deals only with role stressors the first component of the inventory was used (osipow, 1998). moreover, according to osipow (1998), the first component of the questionnaire has six subscales viz., role overload, role insufficiency, role ambiguity role boundary, responsibility and physical kassim kimo ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 40 environment. of these, the first four subscales, viz., role overload, role insufficiency, role ambiguity and role boundary were used to collect data on role stressors in this study. each of subscales composed of fivepoint likert scale items. a high subscale score depicts greater level of role stressor. table 2: results of alpha coefficients for internal consistency of scales used scales reported values of alpha coefficient(r =) alpha coefficient in this study (r =) role overload (ro) 0.78 .86 role insufficiency (ri) 0.85 .77 role ambiguity (ra) 0.79 .75 role boundary (rb) 0.72 .82 furthermore, reliability of osi-r was also determined by internal consistency analyses. alpha coefficient for internal consistency of each scale is greater than 0.7 as shown in table 2 which is acceptable (george and mallery, 2003). data analysis descriptive statistics such as mean & standard deviation were employed to describe general characteristics of the data. an independent-samples ttest was used to compare the mean differences in occupational role stressors (i.e., role overload, role insufficiency, and role ambiguity and role boundary) for public and private higher educational institutions. results and discussion test for assumptions before running the analysis, the underling assumption for t-test was assessed. with regard to normality, it was recommended that the violation of this assumption should not cause any major problems with large enough sample sizes, for instance, when sample sizes greater than 30 subjects (gravetter & wallnau, 2000). in addition to suggestion, the distribution of scores for each group was also checked using histograms obtained on spss version 13 and did not violate any of the underlined assumptions. in all cases, the assumptions were maintained as required. moreover, level of significance was assumed to be 1% (α = .01) in this study. table3: results of mean differences for public and private higher educational institutions on occupational role stressors types of institutions mean std. deviation mean difference sig. public 3.381 .463 .053 1 .01 private 3.111 .514 public 2.999 .438 .0498 2 .007 private 2.863 .487 public 2.853 .530 .063 3 .001 private 2.593 .649 public 3.355 .526 .055 4 .002 private 3.179 .462 1= role overload, 2= role insufficiency, 3= role ambiguity, 4= role boundary kassim kimo ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 41 as can be seen in table 3 above, there was significant difference in mean scores of role overload between public institutions (m=3.381, sd=.463) and private institutions (m=3.111, sd=.514; t (310) = 5.129, p=.01). the result disclosed that the mean score of role overload for public institutions was higher than that of private institutions. further analysis of significant mean difference per item revealed that doing too many different tasks in too little time, performing tasks on their job out of their experience or qualification, scarcity of resources they need to get their job done, working under tight time deadlines and doing more work than it is reasonable appeared to be major factors for role overload among academic officers of public than private institutions. significant difference in mean scores of role insufficiency was observed between public institutions (m=2.999, sd=.438) and private institutions (m=2.863, sd=.487; t (310) =2.735, p<.01). this result also indicated that mean score in role insufficiency for academic officers in public institutions was higher than mean scores of those in private institutions. moreover, based on significant mean difference per item, career progress is not what hoped it would be, being pessimistic about their job, unable to satisfy their needs for success and recognition in their job and unable to learn new skills in their work were found to be causes for role insufficiency among academic officers in public than private institutions. it happened due to the fact that most skilled, experienced and educated academic officers in private institutions are believed to come from public institutions for better payment and other facilities. as can be seen in table 3, there was significant difference in mean scores role ambiguity between public institutions (m=2.853 sd=.530) and private institutions (m=2.593, sd=.649; t (310) = 4.138, p<.01). it is also observed that the mean score in role ambiguity for academic officers in public institutions was higher than those academic officers in private institutions. similarly, significant mean difference per item also showed that lack of getting useful feedback from their supervisor about their performance, being uncertain about what they are supposed to accomplish in their work, lack of setting priority with several tasks and confusion between what their supervisors ask & really want were more pronounced factors among academic officers in public than private institutions. significant difference in mean scores of role boundary was observed between public institutions (m=3.355 sd=.526) and private institutions (m=3.179, sd=.462; t (310) =3.188, p<.01). from the result, it was evident that mean score in role boundary for academic officers in public institutions was higher than those academic officers in private institutions. besides, from significant mean difference per item, confusion between what their institutions expect them to do and what they think is right, supervisors’ conflicting ideas about what they should be doing and frequent disagreement with individuals from other work units or departments appeared to be causes of role boundary among academic officers in public than private institutions. the present findings with regard to role stressors are inconsistent with the studies by lu, et al. (2009), dollard (2001 and widerszal-bazyl, et al. (2000). conclusion & recommendation kassim kimo ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 42 from discussion made above, it can be concluded that there were significant differences in all occupational role stressors (i.e., role overload, role insufficiency, role ambiguity & role boundary) of academic officers between public and private higher educational institutions in oromia regional state of ethiopia, in which the mean scores for academic officers of public institutions were found higher than that of private institutions. on the basis of findings, it is recommended that office duties, responsibilities and accountabilities should be clearly defined in accordance with academic officers’ teaching and research activities. besides, academic officers should also be encouraged to plan and prioritise activities related to teaching, research and administration. to clarify their doubts, reduce incompetence and confusion while performing their office duties, on the job training is also recommended, accompanied by techniques of motivating, recognizing, and rewarding good managerial practices. moreover, further study is also recommended to investigate effects of occupational role stressors among academic officers of public and private higher educational institutions. references assadi, h. 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(2003): occupational stress in australian university staff: results from a national survey. international journal of stress management, 10(1):51-63. ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 45 the ethiopian journal of sciences and sustainable development aims & scope the ethiopian journal of science and sustainable development (ejssd) is a blind reviewed journal published twice a year by adama science & technology university (astu). the ejssd is cross-disciplinary in nature. the journal is the place for exchange of information and research results that describe significant advances in field of engineering, science, technology, business, education, humanities and law, agriculture and health. the ejssd is committed to:  publish original research and review articles and short communications,  serve as a communication medium among professionals in science and social development, and  initiate researchers to focus on community oriented issues that contribute for the sustainable development in the region (ethiopia). the review process considers the originality of the work, relationship to literature, appropriateness of the methodology (i.e. built on an appropriate base of theory, concepts, or other ideas), results and conclusions, the implications for the research, practice and/or society and quality of communication. manuscript should be sent to rpo@astu.edu.et. any queries about submitted manuscript or guidelines should be forwarded to this mail. mailto:rpo@astu.edu.et ethiopian jour ethiopian journal of science and sustainable development 2012. 2(1) 46 the ethiopian journal of sciences and sustainable development (ethiop.j.sci.sustain.dev.) volume 2, number 1, april 2012 issn: 1998-0531 33 © 2019 adama science & technology university. all rights reserved ethiopian journal of science and sustainable development e-issn 2663-3205 volume 6 (2), 2019 journal home page: www.ejssd.astu.edu.et astu review paper the causes and challenges of students’ drug abuse in higher learning institutions: a comprehensive review of related literature kumsa donis likisa adama science and technology university, school of humanities and social sciences, e-mail: kumsalikisa@yahoo.com abstract a number of studies have been carried out on the causes, prevalence and challenges of drug abuse by college and/or university students. however, little literature has been attempted to comprehensively indicate the challenges of drug abuse among university students, strategies utilized to overcome the challenges and implications of the challenges for integrated prevention and intervention approaches. thus, the objective of this comprehensive review of the literature was to assess and organize the literature on the causes, challenges of substance abuse among university students, develop guidelines and seek out alternative solutions that have implications for adama science and technology university (astu) and beyond. the literature has been organized on the prevalence and challenges of drug abuse among college/university students’ worldwide and specifically ethiopian universities. some criteria were set to review the most relevant local and international studies that are rigorous in design, adequate sample size, relevant sample selection procedures and those which have utilized data gathering instruments with high validity and reliability. the findings from the literature indicated that there is a high prevalence of drug abuse among university students worldwide and in ethiopia. the problem is attributed to economic, social, psychological and health factors that demand integrated prevention and intervention approaches. keywords: prevalence, drug abuse, university, students. 1. introduction a number of surveys on substance use indicated that it has become a global phenomenon (zaman et al., 2015). globally, it is estimated that in 2012, between 162 million and 324 million people, corresponding to between 3.5 per cent and 7.0 per cent of the world population aged 15-64, had used an illicit drug — mainly a substance belonging to the cannabis, opioid, cocaine or amphetamine-type stimulants group — at least once in the previous year. teka (2017) also highlighted that 243 million people which is about 5.2% of the world population abused illicit drugs in 2013 and 10% were problem drug abusers (undp, 2015). according to world drug report (2017) by united nations office on drugs and crime in the years 20062015 for world population aged 15-64, it was estimated that 208 million (4.9%) people were drug users out of which 26 million (0.6%) people had drug user disorders. this rose to 255 million (5.3%) drug users in 2015 out of which 29.5 million (0.6%) had drug user disorders which resulted in 5.4% burden of disease most of which caused life loss (zaman et al., 2015). society for the study of addiction (2018) also identified that in 2015, globally, the estimated prevalence among the adult population was 18.4% for heavy episodic alcohol use; 15.2% for daily tobacco smoking; and 3.8, 0.77, 0.37 and 0.35% for past-year cannabis, amphetamine, opioid and cocaine use, respectively. in 2016, it is estimated that globally, around 164 million people had an alcohol or drug use disorder. the global burden of disease attributable to alcohol and illicit drug accounts for 5.4% http://www.ejssd.astu.edu/ kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 34 of the total burden of disease. another 3.7% of the global burden of disease is attributable to tobacco use. according to united nations office on drugs and crime (2014) drug abuse continues to cause a significant toll, with valuable human lives and productive years of many persons being lost. it is associated with loss of about 20 million people globally, and alcohol contributes to a loss of another 17.6 million (teka, 2017). moreover, smoking causes around 5 million annual deaths worldwide. about 250,000 worldwide die due to the use of illicit drugs, 2.5 million die from alcohol-related causes and 5.1 million due to tobacco (unodc, 2011; zanetti et al., 2012). gezahegn et al. (2014) pointed out that the use of substances such as alcohol, khat, and tobacco has become one of the rising major public health and socioeconomic problems worldwide. students make up a substantial population of drug users and are known to use illicit substances as aid in academic efficiency, to cope with their difficult circumstances, for recreation, and to add excitement (zaman et al. 2015). alcohol consumption and the use of substances like heroin, marijuana and cannabis is dramatically increasing among university students both in developing and developed countries (al’absi et al., 2013). for instance, the prevalence of alcohol abuse is 46-62%, and the prevalence of cannabis abuse is 1732% in canadian students (young et al, 2011). about 20% of university students in united state of america (usa) consume alcohol mixed energy drinks and abuse marijuana, ecstasy, and cocaine regularly (snipes & benotsch, 2013), and 20% of russian university students abuse drugs that are not prescribed by doctors (tsvetkova & antonova, 2013). africa now occupies second position worldwide in the trafficking and consumption of illegal drugs (ndinda, 2013). according to united nation (un) statistics 37,000 people in africa die annually from diseases associated with the consumption of illegal drugs. the un estimates there are 28 million drug users in africa, the figure for the united states and canada is 32 million. the abuse of drugs in africa is escalating rapidly from cannabis abuse to the more dangerous drugs and from limited groups of drug users to a wider range of people abusing drugs (asuni & pela, 1986). the most common and available drug of abuse is still cannabis, which is known to be a contributing factor to the occurrence of a schizophrenic-like psychosis. the trafficking in and abuse of cocaine and heroin are the most recent developments in some african countries that had had no previous experience with these drugs. expressing the situation in africa, gezahegn et al. (2014) also pointed out that the rapid economic, social, and cultural transitions that most countries in subsaharan africa are experiencing have created a favorable condition for increased and socially disruptive use of drugs and alcohol. they further argue that substance misuse is a growing problem in ethiopia, as in many developing countries. alcohol and khat are the most frequent substances of abuse in ethiopia. substance abuse among ethiopian university students is also a major problem. for example, the prevalence of substance abuse among undergraduate students at axum university was 44.8% (gebreslassie et al., 2013). it was also reported that there were 53.6% lifetime prevalence of substance abuse among students at hawassa university (kassa et al., 2014) while 24.6% of students at bahir dar university were khat chewers (mulu et al., 2014), and 31% prevalence of lifetime alcohol abuse among medical students at addis ababa university (deressa & azazh, 2011). it was further observed that drinking alcohol, smoking cigarette, and chewing khat are extremely high among students at hawassa university (kassa & deyno, 2014). substance abuse by university students result in high-risk behavior and have both economic and intellectual loss. economically, unrest and consequently wide ranging destruction of life and property is common among drug abusing individuals (ongwae, 2016). a study by bennett and holloway (2018) on the approximate prevalence of drug and alcohol-related crime among university students in seven universities in the united kingdom (n= 7,855) showed that 10% of students who used drugs and about the same percentage who used alcohol had committed substance-related crimes. drug abuse also results in financial deficit which is a global estimated turnover of $332 billion annually (cda, 2013). intellectually, drug abuse results in lack of morals and deteriorating learning standards. continued use of drugs also reduces the ability to think logically and act rationally. kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 35 it has also health risks such as physical and personality deterioration, psychiatric problems, unsafe and early risky sexual practices, intellectual impairment, and a great threat to social, political, and security affairs of a society (mccabe & teter, 2007). for instance, six percent of students at hawassa university reported that they have been engaged in unprotected sex following substance abuse (kassa et al., 2014), 8.2% of jigjiga university students’ respondents were drunk and 10.9% chewed khat during their last sexual engagement (mavhandu-mudzusi & asgedom, 2016). according to martha (2016) recalcitrant of behavior of students, laissez faire attitudes of modern students, non-observance of rules and regulations of the university by the students and lack of skills and knowledge on how to protect themselves from drug abuse have made the problem more escalating. this entails the fact that students need appropriate personal and social skills to protect themselves against drug abuse and to achieve optimum benefits from the educational program. with this regard, no one can underestimate the role of integrated prevention and intervention approaches to curb the problem of drug addiction in the higher learning institutions. in spite of the efforts made in provision of policies, rules and regulations, undertaking research projects, providing alternative solutions, and designing strategies to prevent substance abuse, its prevalence is still rising. thus, academic institutions are responsible to prepare citizens on how to fight the current hurdles of drug abuse and overcome tomorrow's challenges. in their responsibility, universities are expected to prepare students to guard themselves from engaging in any undesirable behavior and activities that spoil their academic activities. in this regard, a number of studies have shown that drug abuse among students disrupt the success of education system as students encounter different personal/psychological, academic and socioeconomic problems and/or maladjustment, which directly or indirectly affect the quality of their education. nevertheless, the challenges of drug abuse and comprehensive intervention or prevention alternatives to be considered in ethiopian universities have not been well described in prior studies and documents. therefore, this comprehensive review of literature is intended to explore research findings related to university students’ drug abuse, causes, challenges and risk factors associated with drug abuse, extract useful guidelines from the reviewed literature and offer solutions in overcoming the hurdles of drug abuse that have implications for astu. 2. methods and materials international and national electronic documents were reviewed to design some integrated approaches and develop guidelines to mitigate the burden of substance abuse among university students in ethiopia in general and adama science and technology university in particular. while searching for relevant literature, the reviewer mainly used databases in google scholar, google search engine, and websites of different organizations. in searching for relevant literature, the following inclusion criteria were used: 1) studies published from the year 2003 to 2018 in the electronic databases; 2) studies published in english; 3) studies that present the prevalence of substance abuse among university students; 4) studies that present the consequences of substance abuse; 5) studies and documents that present strategies and intervention options to mitigate the problem of drug abuse among university students; 6) studies that directly or indirectly reflect the realities of drug abuse in ethiopian universities; and 7) studies that have standard authority, accuracy, and objectivity. rigorousness of the studies’ design, the validity and reliability of instruments used, the sample size, and the sample selection procedures were also taken into account in the selection of the literature. though the literature includes studies from 2003 to 2018, to provide a historical link to earlier work, a few literature published prior to 2003 was reviewed to provide background information on earlier findings. accordingly, 62 research works and international documents were reviewed. the meta-theoretical ground for this review of comprehensive literature is the social ecological model which was developed in 1988 by mcleroy, bibeau, steckler, and glanz based on urie brofenbrenner’s kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 36 multilevel framework (golden & earp, 2012). according to this model, behavior is affected by multiple levels of influence including intrapersonal, interpersonal, institutional, community, and societal factors. consequently, intervention mechanisms need to be multi-levels and integrative so as to consider multiple factors. the cognitive model including knowledge of the consequence was also used as a theoretical framework. the cognitive model focuses primarily on influences of patient’s own beliefs. the most important aspect of this model is the cognition or mental process which relates to perception, judgment and reasoning. it means finding out what core beliefs (conscious or unconscious) are allowing the addiction behavior to emerge. the cognitive model considers whether the person feels stress and believes the addictive behavior is a good solution. the former model focuses on the multiplicity of factors affecting drug abuse and the latter model focuses on the beliefs of the individual about the effect of drug abuse. 3. a review of the literature in global and ethiopian context universities are crucial elements in producing a competent and a good citizen, and improving students’ achievement through the provision of a quality education. universities are also expected to provide supportive environment and protect their students from behaviors that interfere with their academic, career, personal as well as social development. however, this does not mean studying at university is free from experiencing different problems. some of the problems experienced by university students are associated with transition from high school to university life, academic demands, personal relationships and drug use due to different reasons. therefore, in the following sections, types of drugs commonly abused, empirical studies and experiences of different universities regarding the prevalence of drug abuse, challenges and options as intervention mechanisms were discussed. 3.1. types of drugs most commonly abused and associated risk factors despite the availability of rules and regulations that protect holding and using drugs, it has been documented that the prevalence of drug abuse is increasing among university students. although surveys have indicated high rate of misuse of illicit and prescription drugs among college students (zaman et al., 2015), the most commonly abused drugs include stimulants, opioids, benzodiazepines, antihistamines and lsd. alcohol, marijuana, amphetamine, mdma, barbiturates, cocaine, mathaqualone, psychotherapeutics, hallucinogens, ecstasy, methamphetamine, inhalants, heroin, and prescription-type pain relievers, tranquilizers, , and sedatives used for non-medical purposes are also commonly abused drugs. meseret et al. (2018) reported that the most commonly used substances in ethiopia are cigarettes, khat, cannabis, cocaine, and alcohol. marijuana is usually a gateway drug to other illicit drugs (repp & raich, 2014). cannabis is also reportedly a common drug used by university students that usually results in substantially high prevalence of dependence and mental disorders requiring treatment next to alcohol-related disorders. cannabis is a common drug of choice for university students due to its perceived easy availability, coupled with perceptions of a low risk of harm. club drugs such as ecstasy, methamphetamine, cocaine, ketamine, lsd and ghb are used in highincome countries. low price inhalants such as paint thinner, petrol, paint, correction fluid and glue that rapidly induce a sense of euphoria are commonly used in low income countries by young people living on the street. teka (2017), national institute on drug abuse (2003), and bennett and holloway (2014) revealed that factors at individual, interpersonal, institutional, community and societal levels affect substance abuse among university students. factors at individual level include having a family history of drug abuse, which may genetically predispose a person to drug abuse, curiosity (thirst for adventure), early experience with alcohol and drug use during adolescence–while the brain is still developing, personality characteristics such as conscientiousness and agreeableness, high level of emotional liability and impulsivity. the need to stay awake, suicidal tendencies, and mental illness, depression, anxiety, lack of self-control, and perceived low risk of drug use are the other contributing factors. furthermore, the attitude that substance use increase concentration, self-confidence, creativity, imagination kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 37 and enhances academic performance at individual level are contributing factors to drug abuse. the interpersonal factors involve freedom from adults’ close supervision as university life liberates many university students from their parental control, making new friends, peer pressure, and lack of social disapproval (at least by their close friends). early initiation of drug abuse and family background such as lack of mutual attachment and nurturing, ineffective parenting, a chaotic home environment and a caregiver who abuses substances also contribute to university students’ drug abuse (national institute on drug abuse, 2003). institutional related driving forces in drug abuse are transition from high school to university life and lack of proper information and orientation during their first arrival at university, inability to obtain departments of their choice, psychological stressors related to the demand to adapt to new environment, and educational challenges/academic dissatisfaction and lower educational attainment. the other institutional factors that place university students at a greater risk of substance abuse are lack of entertainment facilities, loopholes in the policies, guidelines, rules and regulations, puny control system, looseness of penalty for drug use, lack of devotion among scholars and administrators, and the availability of drugs around university premises. community and societal levels causes are norms and public policies at regional and federal levels, early use of drugs for healing purpose and religious ceremonies and the use of socially approved drugs (nicotine and caffeine) give way to high prevalence and mass addiction due to erosion of traditional theoretical boundaries which also affect the beliefs, value systems and perception towards use of drugs. zaman et al. (2015) provided a detailed account of the epidemiology of drug addiction including cultural values, beliefs, and attitudes to drug use. zaman and his colleagues also pointed out that there are a number of biological, psychological, and social factors, called risk factors that can increase a person’s likelihood of developing drug dependency disorder. these risk factors are eventually discussed. 3.1.1. biological risk factors biological factors related to drug consumption include gender, genetic, neurological, and pharmacological components (zanetti et al., 2012). an individual’s sex continues to be a biological predisposing factor with respect to drug abuse and can be compounded by additional individual differences such as reactivity to novelty and impulsivity (cummings et al., 2011). from a neurological perspective, the immature brains of adolescents can reveal why they engage in risky behaviors. at the same time, they have cognitive constraints including damaged decisionmaking ability, weak analytical ability, psychological barriers, or weak emotional control and expression. from the pharmacological perspective, adolescent drug users are seen as having bodies that are malfunctioning with regard to the production of crucial neurotransmitters, so drugs are used as a form of selfmedication and as a way of coping. the interaction between the pharmacological properties and the physical effects of the drugs habituates the adolescent drug user’s central nervous system to the drug via a neurotransmitter malfunction, which then reinforces the desire to use the drug (lee, 2011). with regard to genetic predisposition, research has demonstrated that genetic makeup is a major factor in vulnerability to drug abuse (volkow & muenke, 2012). while drug abuse is the result of a complex interplay of biochemical, psychological, social and environmental factors, and genetic variance also plays an important role in the susceptibility of adolescents’ drug use and abuse. it is also claimed that the more severe the abuse, the greater the role of genetic factors. 3.1.2. psychological risk factors according to zanetti et al. (2012), the psychological factors associated with drug consumption are related to three principal areas: cognitive, behavioral and emotional. cognitive related factors include impairment in motivation, attention, memory, decision making and problem solving ability. the negative reinforcement model of drug addiction proposed that the escape and avoidance of negative affects is the principal motive for addictive drug use (baker, piper, mccarthy, majeskie, & fiore, 2004). the process of drug addiction is related kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 38 to the natural processes of reward, learning and memory, and their basis is in different neurotransmitter systems (dopamine and glutamate) (kelley, 2004). many drugs present principal effects on these pathways and are able to induce alterations in motivational network and thereby produce maladaptive behaviors. relapse, recovery, and forgetfulness can be explained also as effects of drug use (goldstein & volkow, 2002). behavior related factors include aggressive and violent behavior, and mood swing. bechara and eileen (2004) found a relationship between impairments in working memory and decision-making. impaired decision-making and/or inhibitory control process may explain the continuous risk behaviors common among drug users (bechara & martin, 2004). emotion related factors that are associated with drug use comprise personality aspects such as anxiety, depression, paranoia, panic, mania, difficulty in identifying feelings, and external oriented thought. 3.1.3. social and environmental risk factors the social factors include family, children, friends, and other social relationships as well as health, environmental, religion and legal factors. there are instances when family may contribute to negative behaviors based on the nature of parenting, involvement in drug use, and other negative behaviors (zanetti et al., 2012). dube (2007) stressed the importance of peers. he argues that peer group pressure is one of the major factors contributing to drug abuse particularly among the youth who may seek acceptance from peers. environmentally, adolescents who are reared in communities with high levels of drug use and other negative behaviors tend to become drug users, and adopt and exhibit negative behaviors. lack of access to education, high levels of unemployment and overcrowding, poverty as well as lack of economic opportunities can also contribute to negative behaviors such as drug use (who, 2003a). religious and spiritual beliefs based on faith and trust in god or a greater spiritual being tends to support development of inner strength and the development of a sense of meaning and purpose to life, thus providing an informal means of social control and reducing the likelihood of drug use among the youth (gordon, 2004). involvement in religious or spiritual factors could play a protective role for the adolescent (who, 2003b). 3.2. higher learning institutions and drug abuse the problem of drug addiction now becomes a major problem in ethiopia. the most commonly used substances were alcohol, cigarettes, khat and cannabis which frequently lead to addiction (kebede & abula, 2005). this addiction tradition is often associated with the over growth of night clubs, bars and multiple sexual partnerships in ethiopia (kebede et al., 2005; seme, haile mariam & worku, 2005; regasa & kedir, 2011). university students are also vulnerable to involvement in both licit and illicit drugs as it is probable that youth culture will continue to play a key role in shaping drug use behavior (unodc, 2011). for instance, from a survey (1975-2016) schulenberg, johnston, o’malley, bachman, miech, and patrick (2017) identified that the annual prevalence of using any illicit drugs by us college students was 43%. larimer, kilmer and lee (2005) noted that although alcohol is the primary drug of choice among college students, particularly those of traditional college age (i.e., 18 to 25 years); over half of all college students and young adults have tried an illicit drug at least once in their lifetime. experimentation with substance use increases during this period, particularly for those enrolled full time in college. about 28% to 34% of college students and young adults (19 to 28 years old) have used an illicit drug other than marijuana at least once in their lifetime. in several studies, 28% to 34% of students reported using marijuana and 13% to 18% used illicit drugs other than marijuana. in the study made by palmer et al. (2012) on college students, it was found that marijuana was the most prevalent illicit drug (89%) and pain medication was the most commonly misused (22%). approximately half (45%) of the sample reported lifetime use/misuse of only one substance, 19% reported two, 10% reported three, 8% reported four, 6% reported five, and 11% reported six or more different substances where male students abused substance more than female students. similarly, a study made by takahashi and arakida (2016) on japanese university students shows that 8.4% reported having friends who have used drugs and 2.3% have been invited to use drugs. they also identified that 36.8% of the students reported drugs are easily available. they further identified that 15.1% of the students have smoked cigarettes before starting college, kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 39 and 14.6% had been to a club or rave after being enrolled in college. skidmore, kaufman, and crowell (2016) also identified that college students experience unique challenges, which make them prone to use of alcohol, marijuana, and nonmedical use of prescription drugs. they reported that approximately 26% of male and 19.2% of female full-time college students use illicit drugs. although alcohol is the most commonly used substance (contributor to morbidity and mortality) among college students, a variety of other drugs are also used during this developmental period. a study by çakici et al. (2014) on university students in turkish republic of northern cyprus (trnc) highlighted the lifetime use of cigarette was 69.5% (male students (73.3%) smoke more than female students (64.0%), use of alcoholic beverage was 81.0%, opd use was 15.6% and use of any illicit drugs was 10.9%. similarly, webb et al. (1996) verified that alcohol and illicit drug use has been noted among ten uk university students. binge drinking was declared by 28% of drinkers. 60% of the men and 55% of the women reported having used cannabis once or twice and 20% of the sample reported regular cannabis use. experience with other illicit drugs was reported by 33% of the sample, most commonly lsd (lysergic acid diethylamide), amphetamines, ecstasy (methylenedioxy, methamphetamine), and amyl/butyl nitrate which had each been used by 13-18% of students. 34% of these had used several drugs. drug use had started at school in 46% of the sample; 13% began after entering university. in a study by nižić et al. (2013) on the prevalence of substance use among first-year students (n=420) from six faculties at the university of mostar, bosnia and herzegovina, it was found that the most frequently used substance among students is alcohol; cigarettes are in second place and marijuana (as the only drug with significant frequency of consumption) in third. a study by adibelli and olgun (2016) was conducted on 238 nursing students related to drug abuse detected that 16.4% of the students smoked, 11.3% of them used alcohol, 2.5% of them had tried drug before. it is understood that although the students have positive attitudes about drug abuse, they do not have enough information. for many years, five classes of illicitly used drugs are marijuana, amphetamines, cocaine, lsd, and inhalants. these drugs had an impact on appreciable proportions of young americans in their late teens and 20s. among college students in 2016, the annual prevalence level was 39.3% (schulenberg et al., 2017). a document on substance abuse and mental health services administration (2014) indicated that among full-time college students aged 18 to 22 in 2013, the rate of illicit drug use was 9.4 % for asians, 19.7% for blacks, 21.5% for hispanics, and 25.1% for whites. it was also indicated that 59.4% were current drinkers, 39% were binge drinkers, and 12.7% were heavy drinkers. in the same year, the illicit drugs used initiated among persons aged 12 or older were marijuana (2.4 million), nonmedical use of pain relievers (1.5 million), nonmedical use of tranquilizers (1.2 million), ecstasy (0.8 million), stimulants, cocaine, and inhalants (0.6 million each) in declining order. sarkar, roy and singh (2018) illustrated that substance use is more common during college days due to academic pressure, peer group effects, popularity and easy access to common substances. this was supposed to be more common in hostels. the use of tobacco product was found to be 66% for government engineering college students and 22% for private engineering college students. the use of alcoholic beverage was 72% for government engineering college students and 26% for private engineering college students. the use of cannabis was 46% and 14% for students of government and private engineering college students respectively. in usa, it was found that alcohol, followed by marijuana, causes the greatest harm (ross, virginia & dejong, 2009). yi et al. (2017) study on illicit drug use among university students in the association of southeast asian nations (asean) elucidated that of 7,923 students, the overall prevalence of frequent (≥10 times) and infrequent (1–9 times) and ever (at least once) illicit drug use was 2.2%, 14.7%, and 16.9% respectively. compared to those living with parents/guardians, students living away from parents/guardians were significantly less likely to be frequent (≥10 times vs. never) and infrequent users. this study also identified that the protective factors include older age, higher level of religiosity, and living with parents. kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 40 from quasi-experimental study baseline survey involving 473 first year undergraduate students from two public universities in the coastal region of kenya, mbuthia et al. (2017) have found high prevalence of substance use, with alcohol being the most commonly used substance at both baseline and end-line surveys. despite the intervention being made in one university, the prevalence of drug use increased from 38.9% to 48.9% in the control university and 31.3 % to 55.2% in the intervention university. ongwae (2016) also noted that in kenya some of the commonly abused substances include tobacco, miraa (khat), bhang, alcohol, cocaine, mandrax and heroine. 3.3. the problem of drug abuse in ethiopian universities a study by gezahegn et al. (2014) titled: substance use and associated factors among university students in ethiopia revealed that of the young segment of the ethiopian population, college and university students are at the highest risk of substance use. substance use among ethiopian (haramaya university in focus, n=1023) adolescents is considerably rising. about twothirds (62.4%) of the participants used at least one substance. the most commonly used substance was alcohol (50.2%). the odds of substance use behavior are higher among third year students. joining university often leads to new opportunities, independence from family control, self-decision making, and peer-pressures to use or abuse alcohol or other drugs. out of those who have used drug at least once in their life time, the majority of them started before joining university and the rest after joining university. different reasons were mentioned by students for the use of drugs. the reasons mentioned for drug abuse by the respondents were to increase academic performance, get personal pleasure, and get relief from tension and to stay awake. the other reasons were due to peer influence, academic dissatisfaction, to get acceptance by others, to be sociable, to increase pleasure during sex, and due to religious practice. being a follower of muslim and protestant religions was shown to be protective of substance use. married and depressed students were more likely to use substances than others. the same study identified in axum university a lifetime prevalence of khat chewing (28.7%), alcohol drinking (34.5%), and cigarette smoking (9.5%). a study in debre markos found a lifetime prevalence of substance used to be 14.1%. a study done among college students in gonder university revealed a lifetime prevalence of 13.1% for cigarette smoking and 26.7% for khat chewing. moreover, a study in addis ababa university showed that 31.4% of students’ ever drunk alcohol, 14.1% ever chewed khat, and 8.7% ever smoked cigarette. similarly, a study in jimma university showed prevalence of khat chewing, cigarette smoking, and alcohol intake to be 33.1%, 21.3%, and 36.4% respectively. regarding the pattern of drinking, 135 (66.2%) drink sometimes and 69 (33.8%) drink always. among the current smokers, 107 (81.1%) smoke sometimes and the rest 25 (18.9%) smoke always. regarding the frequency of using illicit drugs, from those who use illicit drugs 79 (44.4%) use sometimes and 15 (55.6%) use always. likewise, according to ephrem et al. (2018) the life time, in the last 12 months and current prevalence of substance use among medical interns of jimma university students was 48.4%, 47.8%, and 43.0% respectively. the major reasons reported were to get personal pleasure, peer pressure and to get relief from tension. ethnicity, religion and having friends who use substance/s were significantly associated with the current use of substance/s. likewise, residence, ethnicity, having friends who use substance/s and coming from an area where substance/s is/are commonly used were significantly associated with the lifetime use of substances. early exposure to substances often predicts future substance use, abuse and dependence with its medical, psycho-social and economic consequences. from ethiopian demographic and health survey (edhs) (2011), ephrem et al. (2018) also identified that the prevalence of alcohol use among men and women was 53% and 45% respectively, and that 11% of women and 28% of men ever chewed khat. a study conducted by meseret et al. (2018) on the prevalence, trends, and consequences of substance use among students of four universities (n=1156), namely, bahir dar, mekelle, jimma, and arba minch universities discerned that on the average 70% of respondents were users of tobacco, 79% were khat users, and 99% were alcoholic beverage users. the mean plots indicated that bahir dar university students kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 41 are the most affected followed by jimma university students. this might be due to the availability of chat in these areas. it is found that there was a statistically significant difference across college, choice of department, and year of the study among students in their experience of substance abuse prevalence, frequency, trend, and consequence. those students belonged to the college of social science are the most affected followed by those belonged to the college of business and economics. those students joined their department with their last choice are also at the most risk and also the mean plots indicated that fourth-year and above students are the most vulnerable. the same study revealed that there was a strong, negative correlation between the prevalence and duty accomplishment, with high levels of substance intake associated with lower levels of duty accomplishment. there was also a negative correlation between the prevalence and academic records, with high levels of substance intake associated with lower levels of academic records. unemployment, lack of social support from families, and the puny drug control system that presently exists in the country have been taken as the main factors that predispose individuals to become substance abuser, whereas lack of curriculum, the looseness of penalty for drug use, lack of devoted scholars, the presence of model scholars for drug abusing, and lack of awareness about the impact of substance use are the contributing factors. 4. essential criteria of relevance to mitigate the burden of substance abuse among university students the following are essential criteria/guideline that have been extracted from the reviewed literatures that might be useful in establishing a relevant model to mitigate the burden of substance abuse among university students in ethiopia, in general and astu, in particular. 1. orientation towards the principle that no one should choose prevention or protection and treatment approach without careful clients’ assessment and adequate information, under the guidance of competent personnel. the following risk and protective factors for substance abuse should be assessed as a prevention program to help decrease unhealthy behavior. a. individual protective factors, such as engagement in positive meaningful activities, positive self-concept, and religious or spiritual beliefs (religiosity) as they inhibit students’ substance abuse. b. peer protective factors, such as positive peer role models and life skills trainings to protect them from peer pressure. c. family factors that are found to be protective for students’ substance abuse such as family attachment, positive parenting style, living in a two parent family, higher parent education, and higher parental expectations about school and university. d. university protective factors including being connected to university or attachment through involvement in different clubs and other university affairs, safe, supportive and caring university climate. e. rewards for prosocial involvement. 2. keeping in mind the multiplicity of personal and environmental influences, ranging from immediate family and institutions (microsystem) to the wider community (macrosystem) that determine the general psychological makeup of students that directly or indirectly affect whether they abuse drug or not; 3. bringing into mind the interrelationship between personal factors (genetic predispositions perception, attitude and personality), family factors, institutional factors (policy and academic pressures) and social factors (culture and availability of drug of abuse) in students’ drug abuse prevention and treatment; 4. understanding the psychological, social, economic, health and academic effects of drug abuse; 5. keeping in mind the flexibility to understand that more than one intervention approach can fit for different students, and also that an individual student may demand a mix of approaches for the same problem; 6. being developmentally orientated and remembering that protection and treatment of drug abuse are continuous, sometimes require long process, and kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 42 that it is the result of a combination of interacting determinants; 7. providing individuals with a broad survey of options to protect themselves from drug abuse, and not simply slotting them into convenient or accidental decisions; 8. exposing students to individuals who have experienced the same problems by assisting them in conducting an interview with someone who already solved problems related to drug abuse, or by doing shadow working; 9. being mindful of the influences of past learning experiences that can influence an individual’s levels of confidence, hope and volition to take up certain paths of life when treating drug abuse; 10. focusing on the process of prevention and treatment, as much as on the outcome, because, in the process, personal growth occurs that might benefit the individual; 11. having well established drug policy, integrating drug prevention programs into education/ curriculum, allocating budget and establish drug free recreation facilities, rehabilitation centre, guidance and counselling service provided that competent counsellors are assigned, awareness raising programs are in place, students have positive attitude towards the service, university commitment and support are realized, all of which will ultimately contribute to the prevention and treatment of drug abuse. 5. conclusion university students are adolescents and young adults who face tremendous pressure and challenges to adjust to the new learning environment. students who join universities face different challenges. adapting to the social and the physical environment constitutes one of the main challenges. adjustment to new peer groups, academic atmosphere, loose family contact, and financial problems are some of the specific challenges. these challenges possibly lead students to personal crisis, mainly emotional disturbance, stress, and other social crisis. these mainly lead to academic failure, drug addiction, social isolation, suicidal attempts and so forth. along with these problems, the need for educating students with desirable life skills and adaptive behavior is crucial which universities have to implement. however, the findings from the literature indicated that the implementation of prevention of drug abuse carries several challenges. these challenges include personal, institutional, social, global, policy and policy implementation factors. increased levels of substance abuse interfere with the development of cognitive, emotional, and social competencies in children and adolescents and may compromise later functioning in important adult domains such as marriage, parenting, and gainful employment. regarding the alternatives to overcome these challenges, we do have many options to address the needs of students in the universities in relation to drug abuse. these alternatives are discussed below. 6. alternatives to be followed today’s college students face a range of drug temptations never envisioned by earlier generations of students. campus administrators have a responsibility to minimize the temptation and opportunity for drug abuse and to help students navigate the new world they inhabit and an opportunity to guide them toward options for a healthier life. a comprehensive approach grounded in environmental management offers a solution to student drug abuse, thereby helping protect students’ health, safety, and educational future. on the basis of the literature reviewed, conclusions made and personal observation, the following recommendations are drawn in the context of ethiopian universities including astu. 1. offer financial support and promote social, affordable drug-free recreational options that do not include alcohol and other drugs, and extracurricular activities (e.g., anti-substance clubs and peer education program) at the university campus. 2. the ministry of education and ministry of science and higher education need to integrate research based and developmentally oriented drug abuse courses (life skills education) in the curriculum in all education levels from primary to the university targeting resistance to peer pressure, decision making skills, goal setting abilities, stress management techniques, communication skills, social skills, assertive skills, avoiding the misconception that substances such as khat and other drugs could enhance mental capability and the teaching of normal behavior so kumsa donis ethiop.j.sci.sustain.dev., vol. 6 (2), 2019 43 that students can make and defend themselves and their sobriety. 3. students need to know about federal, regional, and local laws and the penalties for various violations. 4. modifying the students’ clinic so that students who are affected by substance abuse disorder can get the right treatment and support that involve assessment, intensive case management, motivational interventions, final treatment, rehabilitation and refer students if treatment resources are unavailable on campus. 5. restrict marketing of illicit drugs on and off campus with active participation from law enforcement agencies; arrest and prosecute dealers; and take action against local business whose premises are used to sell drugs. 6. as a comprehensive intervention, develop and enforce campus policy and enforce local, regional, and federal laws to respond to specific drugs of abuse as ethiopia doesn’t have strong policy regarding the abuse of substances such as tobacco, khat, and alcohol. furthermore, the college or university should not be a haven where students think they are immune from the consequences of their actions, and students should be made aware that they will not be protected from legal liability. added to that the government needs to design an economic policy that can replace the economic and livelihood activities that are dependent on substances such as tobacco, khat, and alcohol. besides strategies that aim at reducing substance abuse among students should also consider the universities’ instructors as a large number of instructors in universities abuse substances buying from the same market where the students buy and some of the instructors sit with students to abuse substances. all parties who aim at reducing substance abuse among university students need to pay attention to the cultural background of the students (e.g., khat consumption in the east and alcohol consumption in the north). there is also a need to consider the influence of the social network (people close to them including family members, peers, and relatives) in substance abuse. reference adibelli, d. and olgun, s. 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volume 2, number 2, may, 2015 copyright @2015 (astu) editor-in-chief jeylan aman (phd) astu, adama, ethiopia p.o.box 1888,adama, ethiopia phone +251-221-100051, fax +251-221-100038 email : rpo@astu.edu.et associate editors dr. mngist hailemariam,; astu, adama, ethiopia dr. ziyn engdasew; astu, adama, ethiopia dr. ing. simie tolla, astu, adama, ethiopia dr. lemi guta, astu, adama, ethiopia dr. tsetargachew legese; astu, adama, ethiopia international & local advisory board prof. jang gyu lee; astu, adama, ethiopia prof. dr. g. albert; aau, addis ababa, ethiopia prof. tammo s. steenhuis; cornell university, usa dr. abebe fanta; haromaya university, dire dawa, ethiopia dr. kaba urgessa; ministry of education, addis ababa, ethiopia dr. berihanu adnew; ethiopian economic association, addis ababa, ethiopia dr. shimelis admasu; aau, addis ababa, ethiopia dr. alexander au; german academic exchange service, bonn, germany dr. solomon t/ mariam; bahir dar university, ethiopia dr. asefa abagaz; mekele university, mekele, ethiopia the ethiopian journal of sciences and sustainable development adama science & technology university (astu) issn: 1998-0531 volume 2, number 2, may, 2015 copyright @2015 (astu) contents assessment practices in technical and vocational education and training colleges in oromia regional state …………………………………………………1-15 dr. habtamu kebu and dr. kassim kimo assessment of malt barley production technical efficiency in south eastern ethiopia: stochastic parametric estimation techniques…………..……………….16-30 zegeye tirfe determinants of parental school choice in adama town ………………………..31-40 berhane simie technical and vocational education students’ perception of gender role difference……..41-53 gezahegn gurmu balcha perceptions of students and instructors toward effective teaching paractices: in selected universities, ethiopia…………………………………………………...54-75 dr. berhanu moges assessment practices in technical and vocational education and training colleges in oromia regional state dr. habtamu kebu (khabtamu2008@gmail.com) dr. kassim kimo (mamuda2008@gmail.com) adama science and technology university abstract the main objective of this study was to examine assessment practices in technical and vocational education and training ( tvet) colleges in oromia regional state, ethiopia. to collect necessary data, a total of 105 (m 93 and f 12)sample teachers from four tvet colleges filled in the questionnaire set for the purpose. besides, to supplement information obtained through the questionnaire, focus group discussions with department heads and students of two tvet colleges, were undertaken. descriptive statistics were employed for data analysis. the results obtained elucidated that teachers in tvet colleges under consideration predominantly use assessment methods such as observation, questioning, written test, class work and group presentation which largely assess trainees’ factual knowledge. on the other hand, reflective logs, open book/book review, interview, portfolio evidence, and self assessment are the least used methods. academic subject teachers and apprenticeship supervisorsare important assessorsand the involvement of career officer and trainees themselves in the process appeared to be unsatisfactory.it was also observed that the tendencies to use assessment data for initial guidance and to know entry behavior and program evaluation seemed negligible. besides, from the components of the training program, apprenticeship and among competencies, attitudes and values, and social and interpersonal skills were identified as poorly assessed areas. on basis of the findings, training of teachers on competency based assessment, establishment of assessment unit in the respective institutes and reflection of students on their own work are recommendations forwarded in this study. key words: assessment practices, competency based assessment, performanceassessment, observation. mailto:khabtamu2008@gmail.com mailto:mamuda2008@gmail.com introduction according to unesco and ilo revised recommendations on technical and vocational education (2001), technical and vocational education refers to all forms and levels of the educational process involving, in addition to general knowledge, the study of technologies and related science and the acquisition of practical skills, know-how, attitudes and understanding relating to occupations in the various sectors of economic and social life. it is an aspect of lifelong learning emphasizing preparation of citizens for occupational fields for effective participation in the world of work. technical and vocational education and training (tvet) is an essential element of capacity building in many parts of the world including developing countries like ethiopia. as selemani (2004) indicated that the strategic importance of technical and vocational education and training to social and economic development of a country, lies in the fact that it provides the necessary knowledge and skills for the exploitation of a country through the application of science and technology. tvet specifically avails a country with critical mass competent and skilled personnel required for managing and spearheading the development activities in various sectors of industry and business. the main objective of tvetis to impart, mainly in young people, the knowledge and skills necessary for life after school. to realize this objective close alignment of the training program with labor market requirements is advocated. in order for trainees to successfully complete the training program, they should demonstrate attainment of skills, knowledge and understanding to be able to perform duties of the relevant occupational sector (ecclestone, 1996; mcdonal et al, 1995; rutayuga& kondo, 2004). in tvetcolleges as like in other educational institutions, assessment may be viewed as diagnosis of strengths and weaknesses, predication of potential abilities and aptitudes, provision of feedback to learners and teachers as well. however, due to the close alignment of the training program with labor market and complexity of learning outcomes to be assessed, assessment has a unique place in tvet colleges. as mcdonald et al (1995) indicated, assessment is perhaps the most vital of all processes in vocational education. in that case, a high quality assessment system provides the right emphasis on the different aspects of a course, gives students appropriate feedback, ensures that the right students are deemed to have learnt sufficient, and results in a qualification that is well understood. with the right procedures in place, students can be confident in the quality of their training, and employers can have confidence in qualified students. without assessment, however as the researchers illustrated, any of these could be placed in jeopardy. mcdonald et al (1995) further elucidated that the limitations of traditional assessment and the importance of competence-based assessment in tvet colleges. the researchers pointed out that the traditional assessment emphasizes the comparison of individuals with each other. in vocational education, however, assessment needs to be thought of not as a comparison between individuals, but as a process of collecting evidences and making judgments on the extent and nature of progress towards the performance requirements set out as a learning outcome though it has rarely been the case. prior to education and training policy (1994), tvet was given little attention in ethiopia. however, with introduction of education and training policy, it has gained great momentum both in specialized tvet collegesand comprehensive schools. the policy has given due attention to the prevision of this sector of education with intention of producing middle-level skilled human power that can harness the economic development. cognizant to this fact, many tvet in situations of different levels have been established at different parts of the country, and curriculum was developed for various areas of training based on workforce demand. according tvet curriculum developed by ministry of education (moe,2003), a specific training area consists of main course, supportive courses and common courses. the tvet document points out that the main course evaluation should include inschool training, project work and apprenticeship evaluations. to the best knowledge of these researchers, no studies available with regard to assessment practices in technical and vocational education and training (tvet) colleges. hence,the objective of thisstudywas to survey the assessment practices in tvet collegesand critically examined the extent to which it fits intended purposes. thus, the study specifically tried to answer the following research questions;  what are the assessment techniques often used by teachers in tvet colleges?  to what extents do data obtained from assessment are used to promote learning and teaching in the tvet colleges?  to what extents do assessment practices fit theintended purposes in tvet colleges? 3. methodology 3.1. participants of the study the target population of the study was teachers and students in technical and vocational education training (tvet) colleges which have been training students at 10+3 level in oromia regional state. these colleges wereadama, asella, batu, ambo, woliso, nekamte, shanbu, chiro, shashamene, sebeta, and bale-robetvetcolleges. the participants of the study included a sample of teachers, department heads, academic vice deans, and students from the colleges under the study. 3.2. sample and sampling techniques among the target population of the study, five tvet colleges were selected using random sampling technique. these include woliso,asella, adama, shashemene and ambotvetcolleges. from these colleges three teachers per department were selected using stratified and random sampling techniques. the bases for strata were teaching majorssupportive-common courses, and senior-beginner teachers. besides, the final year high achieverstudents from two colleges (ambo and woliso), and department heads of these two colleges were used for focus group discussion. focus group discussion with students and department heads were conducted separately. interviews were also held with academic vice deans of the two colleges. generally, a total of 112 teachers, of which 105 properly completed and returned the questionnaire, 15 students, 11 department heads and two vice deans were participated in the study. 3.3. tools, procedures of data collection and data analysis to obtain the required information from the samples identified above, questionnaires were developed for teachers. the component of the questionnaires include items related to assessment methods, assessors, purposes of assessment, competencies assessed, assessment issues and training on assessment. most of the items in the questionnaire are closed ended where the subjects asked to indicate their response from suggested alternatives. on the other hand, there were some open ended items where respondents were also requested to deliver rich information. after orientation, the questionnaire was administered to the respondents at their respective college. in addition to the questionnaire, items for focus group discussions were developed both for students and department heads. in the same way, interview questions were developed for academic vice deans. items in the questionnaire were judged by three(two psychology and one curriculum)instructors from adama university on “yes” or “no” checklist for validation. those items who received the support of two instructors selected for use. the remaining items were rejected. the questionnaires were also piloted at bishoftutvetcolleges to identify some pitfalls and possible misunderstandings. cronbach alpha coefficient method was used to analyze internal consistency of the questionnaire.the internal consistency for subscales were ranged from r = 0.70 to 0.77, which are acceptable for research in social sciences (george and mallery, 2003).to analyze the data, descriptive statistics such as frequency and percentage were used. 4. results and discussion the major results obtained from the questionnaires, focus-group discussions and interviews are presented in this part. 4.1methods of assessment various assessment methods and the extent to which they are being used by tvet teachers are presented in table 2. teachers in tvet colleges under investigation identified observation (79%), asking and answering question (70.5%), written test (56.2%), and class work (40%), group presentation (33.2%) as most commonly employed methods. according to their responses these are methods which have been frequently used in tvet colleges. table 2: assessment methods and how frequently they are used assessment methods how frequently used always sometimes never no % no % no % observation 83 79 19 18.1 3 2.9 self-assessment 25 23.8 37 35.2 43 41 class works 42 40 63 60 home works 21 20 76 72.4 8 7.6 writer test(mid& final) 59 56.2 34 32.4 12 11.4 evaluating students artifacts 21 20 59 56.2 25 23.8 case studies/simulations 4 3.80 64 61.0 37 35.2 portfolios evidence 7 6.7 51 48.6 47 44.8 interview 3 2.9 52 49.5 50 47.5 performance assessment 33 31.4 52 49.5 20 19.0 individual presentation 17 16.20 58 55.2 30 28.6 group presentation 37 33.20 58 55.2 10 9.5 reflective logs 29 27.6 76 72.4 open book test/book review 10 9.5 44 41.5 51 48.6 peer assessment 18 17.1 52 49.5 35 33.3 asking and answering questions 74 70.5 28 26.7 3 2.9 micro task 10 9.5 67 63.8 28 26.7 besides, methods rated high on the ‘sometimes’ level include homework (72.4%), case studies/simulation (61%), class work (60% ) performance assessment (33% on always and 49.5 on sometimes) and micro task (with 63.8% ‘sometime’ though the mean is below 2). on the other hand, the following methods are reported to be “never” used by the majority of the subjects. these are reflective logos (72.4%), open book (48.6%), interview (47.6%), portfolio evidence (44.8%) and self assessment (41%). hence, these methods are the least employed methods in tvet colleges in generally. in selecting and implementing assessment methods the crux of the matter is what to be assessed. it is clear that not every goal or educational objective always needs to be assessed. as cacpoly (2005) pointed out planning for assessment requires setting priorities. thus, selecting carefully those learning outcomes, the curriculum is most interested in having students to achieve is crucial. learning outcomes to be assessed specifically in tvet curricula as eccleston (1996) pointed out include: knowledge (recall and recognition), personal skills (monitoring and evaluating quality of own work, interpersonal skills (working with others), cognitive skills, practical skills, and attitudes and values. to assess these learning outcomes check list, question and answer, written test, reflective logs, self-assessment, peer assessment, observation, presentations, task groups, micro task, progress sheets, case studies, and testimonies are among the assessment methods (eccleston, 1996; mcdonlad; 1995 puhl, 1997). the ethiopian tvet curriculum document, moe (2003) also pointed out the need to use continuous assessment in the training program. it is evident that continuous assessment implies frequent assessment of teaching learning process using a variety of most fit techniques in the ongoing process of instruction. the results obtained in this study with regard to the low level utilization of methods such as self assessment, portfolio evidence, interview, and reflective logs elucidated the poor implementation status of modern assessment techniques in the tvet colleges. these are methods found to be most suitable for learning outcomes in the tvet colleges. some of these methods even have long term effect. for instance, puhl (1997) indicated that self and peer assessments play crucial in the context of contemporary assessment process. these methods provide for a wider range of imputes to learners than those provided by a single person such as teacher. they are even skills to be developed the learners and take with them when they leave school and make use of them for life long learning. similarly, mcdonald et al (1995) underscore the importance of self -assessment in the technical and vocational education. according to these researchers, students must leave a vocational education course equipped to engage in self-assessment throughout their professional lives. they need to be able to make reliable judgments about what they know and what they do not know, and what they can do and cannot do. 4.2assessors in tvet colleges the responses to the items related to the involvement of stakeholders in the assessment of trainees and their degree of involvement are summarized in the table 3. these stakeholders are academic subject staff, workplace assessors, assessment unit in the college, career officers/vocational counselor, and trainees themselves. the results depicted that, among these stakeholders, academic subject teachers and workplace assessors are most frequently involved in the assessment process (48.6%and 24.8% respectively). however, assessment unit, career officer and trainees as self assessors are rated by the respondents as far less involved in the assessment process (with the rate of 61.9%, 52.4% and 48.6%, respectively). table 3: assessors and degree of their involvement assessors body degree of involvement always sometimes never no % no % no % academic subject staff 51 48.6 43 41 11 10.5 work place assessors/ line managers 26 24.8 55 52.4 24 22.9 assessment unit in the college 9 8.6 31 29.5 65 61.9 career officer/counselor 14 13.3 36 34.3 55 52.4 trainees (self –assessors) 21 20 34 31.4 51 48.6 as pointed out during the focus group discussions, regarding workplace assessors, though there are involvements during apprenticeship there is concern over its adequacy. likewise, assessment unit, vocational counselor and trainees themselves (as part of peer and selfassessment) are considered as potential assessors; and yet the study reveals that their involvement is almost negligible. this does not seem consistent with literature reviewed in the area which holds the view that all stakeholders (e.g., trainers, employers, parents, trainees and others) should actively participate in the assessment process. this is due to the fact that all stakeholders could employ the results of the assessment for different purposes. 4.3purpose of assessment with regards to the purpose of assessment, four major purposes of assessment, namely, initial guidance and to know entry behavior, certifications and proof of attachment, learning progress and achievement, and program evaluation and institutional development are presented along with rating scale specified in table 4. table 4: purpose of assessment purposes responses always sometimes never no % no % no % initial guidance and to know entry behavior 12 11.4 30 28.6 63 60 learning progress and achievement 56 53.3 43 41 6 57 certification and proof of attachment 60 57.1 32 30.5 13 12.4 program evaluation and institutional development 12 11.4 39 37.1 54 51.4 according to the responses, the results of assessment were mostly used for certification (57.1%) and learning progress and achievement (53.3%). however, results of assessment are never used for initial guidance and to know entry behavior by 60% of the respondents and program evaluation by 51.4% of them. it was also pointed out during focus group discussions that the results of assessment dominantly used for certification and for evaluating students' performance. in fact, entry behavior of trainees requires assessment to place trainees in appropriate fields of study. besides, assessment should also be used as both evaluative and as a learning tool. the results of the study which is presented above showthose teachers in the colleges under consideration emphasize the evaluative dimension of assessment, as this practice is pervasive and persistent in the other program in the ethiopian education sector. 4.4assessment process the responses obtained with regards to the extent to which learning outcomes in the various components of major courses are assessespresented in table 5. among major course components, in-school training and project works were reported to be adequately assessed with the rate of 72.4% and 42.9%, respectively. on the other hand, apprenticeship was rated as the least assessed with the rate of 68.67%. table 5: learning outcomes in the various component of major course and their assessment status components of main course assessment status adequate somewhat adequate not adequate no % no % no % in-school training 76 72.4 28 26.7 1 1.00 project work 45 42.9 50 47.6 10 9.5 apprenticeship 8 7.6 25 23.8 72 68.6 moreover, focus group discussions made with department heads and students, and interviews conducted with academic deans confirmed the existence of serious problems in the assessment of apprenticeship. among these problems, the major one is unwillingness of some organizations to expose trainees to gain the required skills in their fields of study. one of the reason cited by students and department heads about why these organizations are unwilling is that they do not trust the competency of the trainees and, thus, do not allow the trainees to practice and experiment with sophisticated and sensitive machine. similarly, the results of interview held with vice dean revealed that lack of close supervision from both parties (college and workplace assessors) make students reluctant towards their objectives. as pointed out by students regarding the assessment of apprenticeship, the results of assessment and actual apprenticeship practices do not correlate. it was reported by students that some students score maximum mark but have come back to college without any exposure to real workplace skills. in general, department heads, academic deans and students unanimously question the validity and reliability of the result of assessment in apprenticeship at large. however, as reviewed in the literature, apprenticeship is a core component, which requires the attention of all stakeholders to enable trainees to gain competence, confidence, productivity and creativity in their entire endeavor so as to produce creative minds and working hands in the societies at large (moe, 2003; eccleston, 1996). courses in tvet program have various required competencies: understanding and cognitive skills, practical skills, socialand interpersonal skills, and attitudes and values. the below table depicts the extent to which these competencies are assessed. table 6: the extent to which required competencies are assessed competencies of main course assessment status adequate somewhat adequate not adequate no % no % no % academic knowledge (understanding & cognitive skills 51 48.6 44 41.9 10 9.5 practical skills 61 58.1 37 35.2 7 6.7 social and interpersonal skills 19 18.1 30 28.6 56 53.3 attitudes and values 9 8.6 23 21.9 73 69.5 as indicated in table 6, four areas of competencies are presented along with their claimed assessment status. the results reveal that practical skills and academic knowledge (understanding, cognitive skills) seem to be more adequately assessed (with the rate of 58% and 48.6% respectively) than other competencies. the results are consistent with competency areas that have been advised to be assessed adequately in different literatures and tvet curriculum(moe, 2003; eccleston, 1996). however, attitudes and values and social and interpersonal skills as areas of competency were reported to be assessed inadequately with the rate of 69.5% and 53.3%, respectively. however, the two areas have got a paramount contribution for training and producing responsible, competent, and transparent manpower in any fields of study. when these areas are assessed poorly, not as required, the consequences may have negative impact on social services. it appeared that attitudes and values, and social and interpersonal skills areas of competencies might have been assessed by teachers offering common courses alone, civic and ethical education in particular. nevertheless, the issue seriously raised during focus group discussion held with department heads who stated that these areas are underestimated both during in school training and apprenticeship. students themselves shared the same view. from focus group discussions, it can be deduced that the assessment of attitudes and values, and social and interpersonal skills appeared that they did not get sufficient attention. 4.5authenticity of assessment practice in tvet colleges the degree of agreement of respondents with the notion that assessment practices in tvet colleges, is not authentic, is presented in table 7. table 7: respondents’ degree of agreement with the notion that assessment in tvet is not authentic degree of agreement no % strongly agree 21 20 agree 32 31 undecided 5 5 disagree 31 30 strongly disagree 16 15.2 the results indicate that 20% of the respondents strongly agree with the notion, while 31% agree with it. in the contrary, 15.2% and 30% strongly disagree and disagree with the notion, respectively. it is apparent to believe that assessment practice in tvet does not seem authentic. this is inconsistent with what is suggested in the literature.vocational assessments are to be considered more authentic because the student's mastery is demonstrated rather than inferred from his or her responses to questions about the subject (wiggins, 1990; kerka, 1995). 5. conclusion technical and vocational education and training (tvet) refers to all forms and levels of educational process involving, in addition to general knowledge, the study of technologies and related sciences and the acquisition of practical skills, know-how, attitudes and understandings related to occupations in the various sectors of economic and social life. it plays a crucial role in the creation of knowledge and skills demanded by the world of work. thus, it is an essential element of capacity building in many parts of the world including developing countries like ethiopia. regarding tvet curriculum, experts in the field unanimously advocate that the program has to be closely linked to labor market requirements, and its training system should be competencybased. intended learning outcomes in this program are mostly related to skills, knowledge and understanding that enable trainees to perform duties of the relevant occupational sectors, and they are hardly measured by formal written assessment procedures. in a context where what is important is not easily measured by written accounts, traditional means of assessments are not suitable. however, the findings of the study elucidated that teachers in tvet colleges under consideration mainly use assessment methods such as observation, questioning, written test, class work and group presentation. on the other hand, reflective logs, open book/book review, interview, portfolio evidence, and self assessment are the least used methods. academic subject teachers and work place assessors (though various concerns arise on validity and reliability of work place assessment) are main assessors in tvet colleges under investigation. the involvement of assessment unit in the college (does not exist in many colleges), career officer/counselor and trainees themselves in the assessment process is quite limited. the study also pointed out that data obtained from assessment are mostly used for certification and assessing learning progress and achievement. the tendencies to use assessment data for initial guidance and to know entry behavior and program evaluation seem to be insignificant. from the components of the training program, apprenticeships and among competencies, attitudes and values and social and interpersonal skills appearedas poorly assessed areas. in a nutshell, though there is a tendency to use assessment practices that fit intended purposes such as using some continuous assessment procedure, the general status of assessment in tvet colleges under consideration has not get the attention it deserves. it seems, like in many other learning institutions in the country, tvet colleges (though what is to be assessed in the program need improved assessment practices) have not droppedthe traditional assessment practices which have been prevalent in ethiopian education system. to improve the situation the researchers forward the following recommendations.  competencybased training program needs innovative assessment techniques. tvet teachers' knowledge and skills are crucial to implement this innovation. thus, all teachers need to acquire necessary knowledge and skills on competency -based assessment through some form of training.  to improve work-place assessment, further discussion should be conducted with workplace supervisor. work -place assessment format should be also redefined and upon completion of apprenticeship, students must be requested to reflect what they achieved.  to realize the assessment innovation in tvet colleges, establishment of assessment unit with a defined role is essential. 6. references ecclestone, k. (1996). how to assess the vocational curriculum.london: kogan page limited. george, d., &mallery, p. (2003).spss for windows step by step: a simple guide and reference. 11.0 update (4th ed.). boston: allyn& bacon. icdr (1994).guide lines on continuous assessment. addis ababa, unpublished. kerka, s. (1995).techniques for authentic assessment[practice application brief].columbus, oh: eric clearinghouse on adult, career, and vocational education. retrieved from http://ericacve.org/docs/auth-pab.htm (eric document reproduction service no. ed 381 688) mcdonald, r. bound, d., francis, j., &gonei, a. (1995).new perspective on assessment: unevoc studies in technical & vocational education no 4: http://www/unevoc. unesco.org moe (2003).tvet curriculum document, unpublished. puhl, c. (1997). develop, not judge: continuous assessment in the esl classroom. english teaching forum, v. 35.washington d.c. united states information agency. rutayuga, a.b. and kondo, a. (2004).reforming technical & vocational education: the role of nacte on assessment and certification of technical education in tanzania. http://www.spbea.orgfi/accab/kandoratayuga.pdg(7 june 08) selemani, m. (2004).the use of national assessment to enhance quality of technical education. paper presented at national council for technical education (ncte), de res salaam, tanania. teso (2003).pre-service curriculum guides for teacher education program. addis ababa. tge(1994). educational and training policy. aa: empda. unesco, ilo (2001). revised recommendation concerning technical and vocational education. paris: unesco; geneva, retrieved from http//unesdoc.unesco.org wiggins, g. (1990). the case for authentic assessment.eric digests.washington, dc: http://www/unevoc.%20unesco.org http://www.spbea.orgfi/accab/kandoratayuga.pdg(7 assessment of malt barley production technical efficiency in south eastern ethiopia: stochastic parametric estimation techniques zegeye tirfe department of agribusiness management and marketing, school of agriculture adama science and technology university e-mail: zegeyetirfe@gmail.com. mobile: +25191394106, p.o. box 193 asella. ethiopia. abstract the technical efficiency of malt barley production in tiyo and sinana-dinsho districts of arsi and bale zones respectively was investigated using the stochastic frontier production function which incorporates a model for the technical inefficiency effects. primary data were obtained using interview schedule from 2010/2011 cropping season from randomly selected household heads. the estimated stochastic production frontiers model indicates land size of malt barley, dap, seed, labour and oxen labour are significant inputs that determine production level of malt barley. the mean technical efficiency of malt barley farmers is 0.725. this shows that the farmers are not using inputs efficiently. on average, farmers can increase their output by 27.50% without increasing the existing level of inputs by adopting techniques used by the best practice malt barley farmers. the estimated stochastic frontier production model together with the inefficiency parameters shows that education level, economically active family members, cooperative membership, extension visits, access to credit, and plots fragmentation are significant factors that determine efficiency/inefficiency level of malt barley farmers. the results of the study imply that to improve the technical efficiency of malt barley farmers, further promotion of rural household education, better access to credit facilities through improving rural financial market, increasing number of extension visits and promoting cooperative are key factors necessary for policy consideration. key words: stochastic production frontier, technical inefficiency, malt barley. mailto:zegeyetirfe@gmail.com introduction barley is one of the most important cereal crops in ethiopia. the country produces both malt and food barleys. malt barley, however, requires favourable environment to produce a plump and mealy grain. the diversity of barley ecologies is high, with a large number of folk varieties and traditional practices existing in ethiopia, which enables the crop to be more adaptable in the highlands (fekadu et al., 2002). immense potential areas are available for malt barley production to meet demand of the local breweries. most of the demand is met through imports, which account around 69% of total annual requirement (orda, 2008a). to satisfy the ever-increasing demand of the beverage industry, in addition to expansion of production area, increasing production efficiency at plot level is needed. the modern theory of efficiency dates back to the pioneering work of farell (1957).technical efficiency measures how well individual farm transforms inputs into a set of outputs based on a given set of technology and economic factors (aigner et al., 1977). it reflects the ability of a farm to obtain maximum output from a given set of inputs. according to jondrow et al (1982) and ali et al (1996), technical efficiency can be measured either as input conserving oriented or output-expanding orientation. a technically efficient farm operates on the production frontier. but, a technically inefficient farm operates below the frontier. if a farmer is found to be efficient, then productivity enhancement is possible via use of new inputs and technologies that could push the production frontier right ward. however, if farmers are found to be inefficient, then it is possible to improve productivity either by increasing output with the same input bundle or using less input to produce the same output. hence, an empirical measure of efficiency is needed to determine the magnitude of the gains that could be obtained by improving technical efficiency with a given technology. borts and pinherio (1997) analysed technical efficiency of peasant farming fitting cobbdouglas production function (cdpf) to estimate stochastic production frontier (spf) and found average technical efficiency of 70%. oluwatayo et al (2008) studied resource use efficiency of maize farmers and found average technical efficiency of 68%. mohammad et al (2000) analysed technical efficiency of wheat and found the average technical efficiency of 51%. assessing technical efficiency of malt barley has the following significances. it helps to evaluate the impact of previous development programs. and based on the technical efficiency level of each farmer, the determinants of inefficiency would be identified. thus, the efficiency scores in this study are relative values of best farmer in the study areas. the efficiency score of the frontier method are only relative to best farms in the sample, the inclusion of extra efficient firms from other place may reduce the efficiency scores (coelli et al., 1998). this is the drawback of this study. there are no documented empirical studies on technical efficiency of malt barley production in the study area. the objectives of this study are to determine the technical efficiency and determinant of technical efficiency of malt barley production. methodology study area the study was conducted in tiyo and sinana dinsho districts of arsi and bale zones respectively. tiyo district shares border with munesa, ziway dugda, hitosa, and digeluna tijo. the district has 18 peasant associations (pas). the district produces wheat and barley as primary crops. in 2007, population of tiyo was 86,761(csa, 2007). sinana dinsho district has sinana and dinsho sub-districts. sinana-dinsho district shares border with districts of agarfa, gasera-gololcha, berbere, goba, adaba, goro and ginir. this study was conducted in dinsho sub-district. dinsho has 13 pas. the district produces wheat and barley as primary crops. in 2007, population of dinsho sub-district was 39,124 (csa, 2007). sampling technique, sample size and methods of data collection a multi-stage sampling technique was used in choosing the sample to collect primary data. tiyo and sinana dinsho were purposively selected for being they are some of the major malt barley producing districts. two pas from each district that have good potential of malt barley production were purposively selected. rapid appraisals of the study areas were undertaken and lists of malt barley farmers in each chosen pas were prepared and sample of malt barley farmers was selected using simple random sampling procedure. overall, 68 malt barley farmers comprising 38 from tiyo district, and 30 from dinsho sub-district were selected for the 2010/2011 cropping seasons. data collection instrument used was interview schedule. primary data was collected by district agricultural development agents. if farmers had more than one plot of malt barley, then data were collected by aggregation. random sampling was made only for male household http://en.wikipedia.org/wiki/wheat http://en.wikipedia.org/wiki/barley heads because the objective of this research was to assess the efficiency of the operator farmers (table 1). table 1: households, sample size and enumerators in each pa name of peasant association districts number of households number of male heads household that produce malt barley sample size number of enumerators shalla cebeti tiyo 652 234 18 2 dosha tiyo 793 265 20 3 mio dinsho 638 182 14 2 dinsho zuria dinsho 670 210 16 2 source: keble offices econometric model specification crop production in the study area is likely to be affected by random shocks and measurement errors. accordingly, choosing a model that accounts for the effect of random shocks and measurement errors is appropriate. thus, stochastic frontier model was specified in the analysis of technical efficiency of malt barley. the general stochastic frontier model developed independently by aigner et al (1977) and meeusen and broeck (1977) in which an additional random error, v, is added to the non-negative random variable, u, is specified below: ln(yi) = xi +, i = 1,2,3, . . (1) where: i – number of firms in the study areas ln(yi) natural logarithm of the i th firm output/hectare, xi = k+1 row vector whose first element is 1 and the remaining elements are the logarithms of the k input quantities used by the i ih firm,  = (0, 1, 2, . . k) is a (k+1) column vector of unknown parameters to be estimated  = vij uij, vi – disturbance error term, distributed as n(0,𝑣 2) intended to capture events beyond the control of farmers; and ui – non-negative random variable, independently and identically distributed as n + (,𝑢 2) intended to capture technical inefficiency effects of the i th plot. ui assumed to follow half-normal distribution with mean i and 𝑢 2, i = ∑ 𝛿𝑘 𝑍𝑖𝑘 (2) where: z = (1k) row vector of observable farm specific variables hypothesised to be associated with technical inefficiency; and  = (k1) column vector of unknown parameters to be estimated. the maximum likelihood estimates of parameters of the frontier model are estimated, such that the variance parameters are expressed in terms of the parameterisation 𝜎𝑠 2 = 𝜎𝑣 2 + 𝜎𝑢 2 and 𝛾 = 𝜎𝑢 2 𝜎𝑠 2 = 𝜎𝑢 2 𝜎𝑣 2 + 𝜎𝑢 2 . (3) where, the variance ratio 𝛾 parameter has a value between 0 and 1. and 𝛾 equal to zero indicates, the deviations from the frontier are due entirely to noise, while a value of one indicates all deviations are due to technical inefficiency. 𝜎𝑢 2 variance parameters that denotes deviation from the frontier due to inefficiency; 𝜎𝑣 2variance parameter that denotes deviation from the frontier due to noise; 𝜎𝑠 2variance parameter that denotes the total deviation from the frontier (); in the prediction of firm level technical efficiencies, battese and coelli(1988) pointed out that the best predictor of exp(-ui) is obtained by: e[exp(-ui)/ei] = 1−∅(𝜎𝐴+𝛾𝑒𝑖/𝜎𝐴 ) 1−∅(𝛾𝑒𝑖/𝜎𝐴 ) exp(𝛾𝑒𝑖 + 𝜎𝑢 2/2) (4) where 𝜎𝐴 =√𝛾(1 − 𝛾)𝜎𝑠 2; ei = ln(yi)-xi ; ∅ = (.) is the density function of a standard normal random variables. cobb-douglas production function specification: lny = o + 1lnx1 + 2lnx2+ 3lnx3+ 4lnx4+ 5lnx5+ 6lnx6 + 7lnx7+ vi-ui (5) where: y – output of malt barley from the i th plot in quintal/hectare. x1 – land size of malt barley (hectare), x2 – urea used (kg/hectare), x3 – dap used (kg/hectare), x4 – seed rate (kg/hectare), x5 pre-harvesting man-day [(8 hours per day)/hectare], x6 – herbicide used (litres/hectare), x7 oxen labour (oxen pair days/hectare). hypothesis: it is hypothesised that all input variables under equation 5 affects malt barley output significantly. estimation of production frontier is not possible with variables having zero value. to avoid this problem, battese (1997) suggested that it is possible to estimate production frontier by assigning very small value greater than zero for farmers who did not apply the given input. following battese and coelli (1995), mean technical inefficiency effects, i is defined as: i = 0 +∑ 𝛿𝑘 𝑍𝑖𝑘 , (k = 1, 2,. . ., 13) (6) where: zi1 – age of household head (year); zi2 – educational level of household head (years of schooling); zi3 – total land size operated (hectare); zi4 – training; 1 = trained farmer and 0 otherwise; zi5 – economically active family members (number); zi6 – cooperative membership; membership =1and 0 otherwise; zi7 – slope of plots; 1 = plot is plain and 0 otherwise; zi8 –plot fragmentation (number) zi9 –oxen (number); zi10 – extension visits (number of visit per year); zi11 – access to credit; 1 = yes and 0 otherwise; zi2 malt barley farming experience (year); zi3soil fertility status; 1 = fertile and 0 otherwise; and 𝛿𝑘 – unknown parameters to be estimated. hypothesis: it is hypothesised that all variables except plot fragmentation mentioned under equation 6, affect technical inefficiency negatively. the one-stage estimation procedure of the inefficiency effects model together with production frontier function is implemented in the study. the technical efficiency predictor implemented in the program is obtained by replacing the unknown parameters in equation (4) with the maximum likelihood estimates. the above battese and coelli (1995) models, in equations (1) to (6) can be estimated using the computer program, frontier version 4.1 software developed by coelli (1995). before model estimation assumption of normality, multicollinearity and heteroscedasticity would be checked. result and discussion descriptive result table 2, the household head was on average 48.2 years old. the average year of schooling of the household heads was 2.56 years. development agent visited the farmer 11.6 times for extension service per year on average. table 2: descriptive statistics of continuous variables variables unit of measurement mean standard deviation age of household head year 48.2 14.5 economically active family members number 3.98 1.24 education level year of schooling 2.56 1.03 total land size cultivated hectare 2.45 1.35 oxen number 2.86 1.4 plot fragmentation number 2.4 1.3 extension visit number/year 11.6 1.2 malt barley farming experience year 12.4 5.7 source: own computation table 3 indicates, only 32.35 percent of the respondents have access to credit service. among the respondents 70.59 percent reported that their lands are plain. this may be one of the reasons why 76.47 percent respondents articulated that their lands fertile. table 3: descriptive statistics of dummy variables variables number percent soil fertility status( fertile = 1) 52 76.47 training (yes = 1) 17 25.00 access to credit( yes = 1) 22 32.35 slope (plain = 1) 48 70.59 cooperative (member = 1) 62 91.18 source: own computation table 4, the sample respondents on average used 63.2 kg of dap, 15.6 kg of urea, 28 oxen pair day, 58.9 man-day, 187.2 kg of malt barley seed and 0.5 litre of herbicide on a hectare. the output of malt barley from a hectare is 26 quintals. table 4: descriptive statistics of input and output variables of malt barley production variables unit of measurement mean standard deviation output of malt barley quintal/hectare 26 8.2 land size of malt barley hectare 0.68 0.85 urea fertilizer kg/ hectare 15.6 12.4 dap fertilizer kg/ hectare 63.2 24.1 seed rate kg/ hectare 187.2 32 human labor man-day/ hectare 58.9 20.4 herbicide liter/ hectare 0.5 0.42 oxen labor oxen pair day/ ha 28 12.15 source: own computation parameter estimates of the stochastic frontier model equations 3 to 6 were used to estimate stochastic frontier model. before undertaking the econometric analysis, the data was checked for its normality, multicollinearity and heteroscedasticity using different batteries of tests. in table 5, sigma square (1.45) is statistically significant. this indicates a good fit and the correctness of the specified distribution assumption of the composite error term. the variance ratio gamma is 0.95. the result suggests, over 95% of the variation in malt barley output among farmers in the study area is due to the differences in their technical efficiencies. this result is consistent with the finding of yao and liu (1998). the generalised likelihood ratio test (lr = 7.6816) is significant. this means the presence of one-sided error component. table 5 shows, land size of malt barley, dap, oxen labour, and seed and human labour have a coefficient of 0.53, 0.129, 0.220, 0.42 and 0.203, respectively. land sizes of malt barley, dap and seed rate are significant at 1% level. and oxen and human labours are significant at 5% level. the result agrees with the hypothesis that land size of malt barley, dap, oxen labour, seed rate, and human labour have significant impact in determining the output level of malt barley table 5: the maximum – likelihood estimates of the frontier model variables cob-douglas spf coefficient t-ratio frontier functions constant 0.92 2.16 ** land size of malt barley 0.530 6.13 *** urea 0.056 0.179 dap 0.129 3.45 *** seed 0.420 4.42 *** labour 0.203 2.152 ** herbicides 0.034 0.194 oxen labour 0.220 2.07 ** sigma-squared 1.45 3.78 *** gamma 0.95 57.57 *** log-likelihood function -74.2 lr test 7.76 source: model output ***, **,* indicate significance level of 1% 5%, and 10% respectively technical efficiency scores table 6, there is a considerable difference in technical efficiency among farmers that ranged from minimum of 0.060 to a maximum of 0.932 while the mean was 0.725. the implication of this statistics is that farmers are technically inefficient while producing malt barley. in the short run, there is a scope for increasing malt barley production by 27.50% without increasing the existing level of inputs by adopting techniques used by the best practice malt barley farmers. table 6: estimated technical efficiency of malt barley farmers at plot level efficiency class frequency percentage 0.01– 0.10 3 4.41 0.11 – 0.20 2 2.94 0.21 – 0.30 6 8.82 0.31 – 0.40 4 5.88 0.41 – 0.50 6 8.82 0.51 – 0.60 5 7.35 0.61 – 0.70 7 10.29 0.71 – 0.80 10 14.71 0.81 – 0.90 11 16.18 0.91 – 1.00 14 20.59 mean 0.725 minimum 0.060 maximum 0.932 standard deviation 0.195 source: model output determinant of technical inefficiency identifying factors that determine the efficiency level of individual farmers is the foremost interest behind measuring technical efficiency/ inefficiency. the technical inefficiency effect estimates revealed that education level, economically active family members, cooperative membership, plot fragmentation, extension visits, and access to credit are found to be the significant factors that affect technical inefficiency. since these variables are found to determine inefficiency, their sign should be interpreted carefully in case of determinant of technical efficiency (table 7). education negatively and significantly (at 5% probability level) affects technical inefficiency (table 7). education can enhance farm productivity directly by improving the quality of labour, by increasing the ability to adjust to disequilibria, and through its effect upon the propensity to successfully adopt innovations which eventually leads to higher technical efficiency. the result is similar with the findings of parikh et al (1995). this makes valid the hypothesis that education affects technical inefficiency negatively. economically active family members were found to have a negative and significant (at 5% probability level) effect on technical inefficiency (table 7). this finding supports that of parikh and shah (1995). larger and economically active family members are source of labours. it suggests that technical efficiency of malt barley increase as the number of economically active family members increase in the family. the result supports the hypothesis that economically active family members affect technical inefficiency negatively. extension visit was found to have a negative and significant effect (at 1% probability level) (table 7). the possible reason may be farmers are able to use modern techniques of malt barley farming involving land preparation, planting, application of agrochemicals and harvesting timely due to the guidance of the development agents. the result supports the hypothesis when the number of extension visits increase it affects technical inefficiency negatively. the result supports the finding of xu and jeffrey (1998). availability of credit service was found to influence technical inefficiency negatively and significantly (at 5% probability level) (table 7). application of modern farm technology to increase agricultural output had increased financing needs of farmers. easy and cheap credit service availability is the quickest way for boosting agricultural production. credit is provided for relief of distress and for purchasing seed, fertilizer, cattle and implements (yusuf, 1984). as hypothesized, availability of credit service was found to be negatively and significantly affect technical inefficiency. plot fragmentation affected technical inefficiency positively and significantly (at 5% probability level) as it was hypothesized (table7).the possible reason is the costs associated with fragmentation are seen principally in terms of inefficient resource allocation (labour and capital) and the resulting cost increase in agricultural production. the result is consistent with parikh and shan (1995). cooperative membership was found to affect technical inefficiency of malt barley productivity negatively and significantly (at 1% probability level) as it was hypothesised (table 7). cooperatives supply their members with inputs for agricultural production, including seeds, fertilizers, and machinery services timely to its members. thus, timely availability of agricultural inputs enhances agricultural productivity. this agrees with the findings of onyenwaku and fabiyi (1991). table 7: stochastic production frontier for determinants of malt barley output inefficiency model coefficients standard error t-ratios constant 3.32 1.366 2.43 ** age -0.29 0.240 -1.21 education -0.14 0.063 -2.240 ** total land operated by farmer -2.11 1.998 -1.056 training -0.16 0.485 -0.33 economically active family members -0.20 0.089 -2.25 ** slope of the plot -0.42 1.308 -0.321 plot fragmentation 0.21 0.097 2.167 ** number of oxen -0.01 0.010 -0.982 extension visit -0.20 0.042 -4.76 *** access to credit -0.42 0.212 -1.982 ** malt barley farming experience -0.284 0.095 -1.088 soil fertility -0.214 0.193 -1.11 cooperative membership -3.68 0.904 -4.07 *** variance parameters sigma-squared 1.45 0.381 3.78 *** gamma 0.95 0.017 57.57 *** log-likelihood function -74.2 lr test 7.76 mean efficiency 0.725 number of observation 68 source: model output ***, **,* indicate significance level of 1% 5%, and 10% respectively conclusion the objective of this study was to examine technical efficiency and determinants of technical inefficiency of malt barley farmers in south eastern ethiopia. the estimated stochastic production frontiers model indicates land size of malt barley, dap, seed, human labour and oxen labour are significant determinant of malt barley output in the study area. the mean technical efficiency of malt barley farmers is 0.725. the result shows that the farmers are not using inputs efficiently. this implies farmers can increase the output they are getting by 27.50% without increasing the existing level of inputs by adopting techniques used by the best practice malt barley farmers on average. malt barley farmers’ technical inefficiency will decrease with increase in their years of schooling, economically active family members, cooperative membership, extension visit and access to credit. on the contrary, as the number of plot fragmentation increase farmers’ technical inefficiency also increase. the result implies that to improve the technical efficiency of malt barley farmers, further promotion of rural household education, better access to credit facilities, promoting number of extension visits and farmers cooperative are needed. acknowledgment i would like to acknowledge all individuals and organizations that directly or indirectly contributed to the successful completion of this study. reference aigner, dennis j., c. a. knot lovell, and peter schmidt (1977): formulation and estimation of stochastic frontier production function models. journal of econometrics 6, no. 1: 21–37. ali f. ,parikh a., and shah m.k. (1996): measurement of efficiency using the behavioural and stochastic cost frontier approach. journal of policy modelling. 18 (3): 271–287. battese g.e. (1997): a note on the estimation of cobbdouglas production functions with some explanatory variables having zero values. journal of agricultural economics, 48(2), 250-252. battese g.e., and coelli t.j. (1988): prediction of farm – level technical efficiencies with a generalized frontier production function and panel data. journal of econometric, 38: 387–399. battese g.e., and coelli t.j. (1995): a model for technical inefficiency effects in a stochastic frontier production for panel data. empirical economics, 20: 325–332. borts e. btavo-ureta and antaonio e. pinherio (1997): technical efficiency of peasant farming: evidence from the dominican republic. the developing economies xxxv-1(march 1997): 48 – 67. csa (central statistical agency) (2007): the 2007 population and housing census of ethiopia:preliminary report. addis ababa. coelli, t.j. (1995): recent developments in frontier modeling and efficiency measurement. australian journal of agricultural economics, 39(3): 219–45. coelli, t.j., d.s.p.rao and g.e.battese. (1998): an introduction to efficiency and productivity analysis. klwuer academic publishing, bosten, dordrecht/ london,p,154249. farrell, j.j. (1957): the measurement of productivity efficiency. j. royal statistical soc., series a, 120: 253–90 fekadu alemayehu, berhane lakew & berhanu bekele (2002): on-farm evaluation of promising food barley cultivars in north and nw shewa zones. pp 200–211 jondrow j., lovell c.a k., materov i., and schmidt p. (1982): on the estimation of technical inefficiency in the stochastic frontier production function model. journal of econometrics, 19: 233–238. meeusen w., and van den broeck j. (1977): efficiency estimation from cobb douglas production functions with composed error. international economic review, 18: 435–444. mohammed hassena, h farah. w. mwangi and belay k. (2000): factors influencing technical efficiency of crop production in assasa district, ethiopia. unpublished m,sc. thesis. alemaya university. oluwatayo i.b., a.b. sekumade and s.a.adesoji (2008): resource use efficiency of maize farmers in rural nigeria: evidence from ekiti state. world journal agricultural sciences 4(1) : 91 – 99, 2008. onyenwaku c.e. and y.l. fabiyi (1991): a comparative analysis of cooperative and non-cooperative farmers in food production in imo state, ife journal of agriculture. 13: 90-96. orda (organization for rehabilitation and development in amhara) (2008a): baseline survey of six malt barley potential woredas of north and south gondar zones of the amhara region. april 2008. bahir dar. parikh, a., f. ali and m. k. shah (1995): measurement of economic efficiency in pakistan agriculture, american j. agric. eco. 77:675 – 85. parikh, a. and k. shah (1995): measurement of technical efficiency in the north-west frontier province of pakistan. journal of agricultural economics, 45: 133–37. xu, x. and s.r. jeffrey (1998): efficiency and technical progress in traditional and modern agriculture: evidence from rice production in china. agricultural economics, 18: 157–65. yao, s. and z. liu (1998): determinant of grain production and technical efficiency in china j. agric. econ.49:171-84. yusuf m. (1984): farm credit situation in asia.‖ asian productivity organization, tokyo, japan, pp 455– 494 determinants of parental school choice in adama town birhane sime geressu (assistant professor) school of educational sciences and technology teacher education, adama science and technology university, p.o.box 1888, ethiopia, e-mail: birhane_200@yahoo.com abstract the purpose of this study was to examine factors that determine parental school choice in adama town, ethiopia. to meet the intended objectives of the study, the researcher used quantitative survey research method supported by qualitative data. participants of the study included 100 parents, 4 school principals, 4 school board members and 2 adama town educational experts. closed and few openended questionnaires and semi structured interviews were employed to solicit data from key informants in the study setting. data were analyzed through both qualitative and quantitative methods. the study result showed that 14 factors influenced parents to choose schools. however, the major factors that influence parents to choose private schools were medium of instruction, assessment policy of schools, and national examination result. thus, the study suggests the urgency of government intervention and community participation in public schools and the importance of strengthening experience sharing practices between public and private schools. key terms: parents, child, public schools, private schools, school choice 1. introduction education is a life-long process that brings change in human behavior. it is the key to development, which every human being is seeking (olaniyan and okemmakinde, 2008). it improves human capabilities and helps an individual to improve personal health, increase productivity and earnings. moreover, education has poverty reducing effect, contributes to democratization, and promotes peace and stability (ibid). recognizing this, now a day’s governments, families and individuals gives high attention to the provision of education. mailto:birhane_200@yahoo.com in this regard, several studies have been conducted on the contribution of education for development and major factors influencing parents to choose schools to their children which is the major focus of this study. as it is indicated hereunder factors influencing parents to choose schools for their children are categorized in to three major parts (bukhari and randall, 2009). these are: parents and children related, socio-economic and school systems associated factors. parent-child related factors: the study conducted by gallop poll (cited in bukhari and randall, 2009) reveled that parents chose schools for their child for reasons related to religion, a desire for strict discipline, moral values, and being closer to home. another similar study was also carried out by edwards and richardson in 1981(cited in bukhari and randall, 2009) to determine why 1,927 students left the public schools in order to be enrolled in private schools. in the same way, the results of the study showed that lack of discipline, religious values, overcrowdings of classes and nature of curriculum content were the primary reasons that influence parents to choose private school for their children. furthermore, echols and willms (1995) examined three government schools and reported 30 reasons for the same case. happiness of the children was emerged as the most important reason, followed by good discipline of the school. socio-economic related factors: le and miller (2003) examined parental choice among schools and found out that public and private school parents tightly clustered around social and economic factors. public school parents expressed most concern with the affordable school expenses and private school parents were mostly concerned about the student demographics of the school, which were similar to their family’s high socio-economic status. other study conducted in hong-kong by shun-wing (2000) revealed that school preference depends on work, production and ownership relation as well as socio-economic status of each class. fossey (1994) also worked on factors determining parental preferences of schools and found out that low-income parents placed lower values on academic characteristics when choosing schools. parental school choice is also associated with parent’s occupational status. parents with higher occupational status prefer private school over public school for their children. according to gloman and ravikumar (1992) private education can produce higher per capita income and the societies choose public education if majority of its agents’ income is below average. school related factors: according to dronkers and robert (2003) parental decision in educating their child depends on satisfaction and dissatisfaction of educational activities and the outcome of schools. according to the scholars, if parents are not satisfied with public schools, they will have no other option than the private schools. moreover, parents consider educational environment, teacher-student ratio, teachers’ qualification and class size as determinant factor in choosing best schools for their child (lai, sadoulet and janvry, 2009). furthermore, hoxby (2002) found that school choice by parents has also relation with the increasing demand for high quality of teachers. besides, at the time of school selection, parents most of the time keep in mind the institution’s quality, teacher’s effort, command over the subject and the academic achievement of their children. to investigate the extent to which the findings of different countries are consistent with ethiopian context the present researcher discussed with few parents, teachers and school board members found in adama town and have recognized that there is perception difference among parents in selection of schools for their child. according to adama town education office 2010 annual report, of town, the public education sector has been a major provider of educational service, accounting for about 63.7% of primary enrollment in the year 2009/10. besides, in the past five years (2006/7-2009/10), the rate of growth for private schools was 121% and 27.8% for public. similarly, the rate of growth of student population was 110.4% in private schools and 27.6% in public schools. thus, the purpose of this study was to find out major factors that influence parental decision in selection of schools for their child in adama town. to meet the stated objective the study was guided by one major question. main question: 1. what factors determine parental school choice in adama town? sub questions 2. how do parents weigh the teaching and learning processes alongside other aspects of their child’s wellbeing when selecting schools? 3. how do parents in adama town perceive private schools? 4. methodology this study aimed at finding out factors which influence parents’ school preference in adama town. the methodological approach used in this study was quantitative survey research method supported by qualitative data. to make the study manageable, by using purposive sampling technique four schools (two public and two private, 50%) that are highly preferred by parents and that had presented candidates for grade 8 national examinations for more than 8 years were selected. then, 100 parents (25 from each school) of grade six high ranked students (rank 1-10) were chosen by using simple random sampling technique. moreover, by using purposive sampling techniques 4 school principals and 4 school board members from each school as well as 2 educational officials from adama town education office were taken as sample respondents and interviewed. the main data collection instrument was researcher constructed questionnaires. to ensure the reliability of the instrument and establish its validity the questionnaires were pilot tested in one private and one public school which were not involved in the actual study. interview was also used to supplement the data collected through questionnaire. finally, the quantitative data were analyzed by using percentage, mean and standard deviations while the data collected through interview were analyzed by using case by case and cross case analysis. 5. results and discussions 5.1 determinants of parental school choice 5.1.1 parental perception on private schools table 1. assessment on parental perceptions on private schools (n=100) items mean sd when compared to public school, private schools:  educate child properly 4.05 .79  have teachers with required qualification 4.29 .62  have teachers with required educational experience 1.67 .58  have teachers which are more committed to work 2.47 1.05  have teachers which are better motivated in terms of remunerations 2.36 1.11  gives attention for foreign languages 4.11 .78  environment encourage the process of teaching and learning 3.98 1.04  offer more diversified and flexible curriculum 4.60 .49 mean < 2.50 low; mean 2.51-3.75 average; mean 3.76 -5.00 high as indicated above, parent informants perceive that private school have teachers with required qualification; give more attention to foreign language and educate their children more than public school. in addition, the environment of private schools encourages the process of teaching and learning and the schools also offer more diversified and flexible curriculum than public schools. contrary to the above, during interview session, one public school board member said “public school teachers can educate children better than private schools and i evaluated that the competence of my students both in public and private schools and i observed much better achievement from my child who attend in public school”. nevertheless, teachers in private school lack the required educational experience, less commitment for work and they are not motivated in terms of remunerations. regarding the commitment of teachers one of the private school board members said that “the reason for the commitment of private school teachers is not the love they have to work; rather the strict control made by owners of the school and school principals. in addition, i (the researcher) also physically observed both private and public schools and confirmed the difference. according to my personal observation in public schools one combined desk is used for four students, the blackboards are cemented on the wall and teachers have no chair to take a seat and correct classroom assignments and to do other related works. school board members, school principals, and educational officials also verified the inadequacy of teaching and learning facilities in public schools. according to them, the root cause of the problem is the existence of large number of students in the class, low parental involvement, and inadequacy of budget allocated for schools from the government. in general, the environment of private schools is more conducive for teaching and learning process than public schools. 5.1.2 status of school resources the study included two public primary schools (adama number 3 and 4) and two private schools (nafyad and st. joseph). to know the major differences among them, documents were assessed and the following results were obtained. table 2. availability, adequacy and usability of education resources school resources private schools public schools nafiyad st. joseph adama no. 3 adama no. 4 no. of teachers male 18 17 21 19 female 16 21 20 23 total 34 38 41 42 no. students male 546 455 1254 1221 female 412 432 1312 1134 total 958 887 2566 2355 teacher-student ratio 1:47 1:45 1:62 1:56 no. of classrooms 24 (full day) 20(full day) 24 ( two shift) 28 ( two shift) student-classroom ratio 1:40 1: 44 1: 107 1: 84 no. of computers 25 32 1 1 source: adama town education office, 2010 as it can be seen from table ii, teacherstudent and student-classroom ratio in private schools is smaller than public schools. besides, the teaching and learning process in private schools is full day, however, in public schools, it is in two shifts. moreover, private schools have few computers, however, public schools do not have adequate computer even for office work. this data is consistent with elacqua, gabierno, & ibanez (2005) findings that showed class size, availability of adequate quality teachers and school facilities determines parental school choice. 5.1.3 teaching and learning process table iii. assessment of teaching/learning process in schools no type of actions mean of respondents (n=100) public school parents ( n=50) private school parents (n=50) 1 teacher gives relevant homework/ assignment on all subjects 1.65 3.75 2 teachers promptly mark the assessment 1.78 3.98 3 teachers are ready to assist child 4.56 3.43 4 teachers are friendly with child 3.98 3.78 5 child complains about not understanding what teachers teach 4.12 3.76 6 child complains about being beaten by the teacher 4.15 3.85 7 how often do you check your children school work 2.11 4.54 8 parents come to discuss their children academic performance 1.33 4.57 mean < 2.50 low; mean 2.51-3.75 average; mean 3.76 -5.00 high as can be seen from item 1 of table iii, the extent of giving assignments for children by the teachers on all subjects was rated low in public schools and high in private schools. besides, teachers marked the assignment punctually in private schools than in public schools. however, the level of assistance given for the child and the degree of relationship teachers have with students as a father, mother and close friend was good both in public and private schools. besides, both in public and private schools child has more right to ask question regarding the subject matter and to complain not to be beaten by teachers. finally, the extent of parental involvement in teaching and learning process was forwarded for informants. in this regard, private school parents were better involved than public schools in checking children school work and in discussing with teachers and school management about their children’s academic performance. however, the finding of the study showed that parental involvement in supporting students at home and discussing on academic issue in public schools were low. 5.1.4 students academic achievement after taking into account differences on the availability, adequacy and usability of education resources, the next issue assessed from school document was the result of students in grade 8 national examinations over the past 3 years. table 4. grade 8 national examination result of sample schools school’s name 2007/8 2008/9 2009/10 admitted pass fail admit. pass fail admit. pass fail adama no. 3 498 404 (81.12%) 94 (18.88%) 670 524 (46.4%) 146 (53.6%) 518 236 (45.56%) 282 (54.44%) adama no. 4 456 321 (70.4 %) 135 (29.6%) 545 322 (59.1%) 223 (40.9%) 564 287 (50.9%) 277 (49.1%) nafyad private 412 396 (96.1%) 16 (3.89%) 312 311 (99.68%) 1 (0.32%) 436 378 (86.7% 58 (13.3%) st. joseph private 207 202 (97.6%) 5 (2.4%) 190 190 (100%) ----251 218 (86.85%) 33 (13.15%) source: adama town education office, 2010/11 as it can be seen in table iv above, students in private schools achieve better result than public schools. this was also true for coulson (1999) findings that said parental school choice in private schools are determined by academic quality and school’s good academic performance. unexpectedly, however, one school board member from public school said that “the result of national exam doesn’t necessarily show the excellence of private schools; it rather can be the outcome of the commitment of the child and may be the support given at home”. he backed up this argument with the evidence that almost all private school students were admitted at private school had to pass entrance examination at the beginning of the academic year. 6. conclusion this study explored the determinants of parental school choice in adama town. the study showed that: national examination result, medium of instruction , attention given for foreign language, availability of educational resources, assessment policy of schools the strict follow up and support given to their child and child influence were the most important variables which affect parents’ decision regarding selection of public or private school in the study area. moreover, national examination results, the way children are treated, freedom of a child to complain, parent teacher relation, class size and teacher student ratio were also factors that determines parental school choices in adama town. in general, in most cases the findings of this research are consistent with the previous researches findings conducted in various countries and cited in this study. however, unlike the previous finding medium of instruction and the assessment policy of schools are found to be new factors that determine parental school choice in adama town. finally, the result of the finding implies the importance of government intervention in allocating adequate fund and the society ought to know that the current status of public schools is poor and they should participate in all educational matters. besides, public and private schools should share their experiences with each other and work together to attain educational objectives. acknowledgement i would like to express my deepest and heartfelt appreciation and thanks to all sampled schools and all informants who contributed to the result of this research by making information easily accessible. references bukhari, p. and randall,e. (2009).exit and entry: why parents in utah left public schools and chose private schools. utah: brigham young university, p23-27 coulson, a. (1999). market education: the unknown history. new brunswick, nj: transaction publisher, p-65 dronkers, j. and robert,p. (2003). the effectiveness of public and private schools from a comparative perspectives, working paper sps no.2003/13 echols, f. and willms,j. (1995). reasons for choice in scotland. journal of education policy, 10 (2) elacqua, g. gabierno, e., & ibanez, u. (2005). school choice in chile. an analysis of parental preferences and search behavior. national centre for study of privatization in education, no.35 fossey, r. (1994). open enrollment in massachusetts: why families choose. educational and policy analysis. cambridge: massachusetts gloman,g. and ravikumar, b. (1992). public versus private investment in human capital: endogenous growth and income inequality, the journal of political economy, 100 ( 4) hoxby, caroline m.(2002).school choice and productivity. working paper 8873. cambridge: massachusetts, p-98-101 lai, f., sadoulet and janvry,a. (2009). the adverse effects of parents’ school selection errors on academic achievement: evidence from the beijing open enrollment program. economics of education review, no 28 le,a., and miller, p. (2003). choice of school in australia. determinants and consequences. the australian economic review, 36 ( 1) olaniyan,d. and okemakinde, t. (2008). human capital theory: implications for educational development, pakistan journal of social science, 34 (5 ) shun-wing (2000). the impact of social class difference on parent involvement in school education in hong kong. educational journal, 28 (2) technical and vocational education students’ perception of gender role difference gezahegngurmubalcha adama science & technology university, p.o.box 1888, adama, ethiopia abstract this study is aimed at investigating perception of gender-role stereotypes and the associated factors for students in technical and vocational education and training (tvet) colleges. specifically, it is to: determine the gap between female and male students’ in perceiving gender role stereotypes, identify the socioeconomic factors bringing significant variance students’ perceived gender-role stereotypes, and identify whether males or females are affected by perceiving gender role stereotypes. the study is important to revise and to implement tvet curriculum and strategy. quantitative survey research method was employed for the study. the study participants were 310 students drawn from tvet colleges in oromia regional state using multistage sampling technique. data collected using items of likert scale format were analyzed using descriptive statistics, t-test, and analysis of variance. the result indicated moderately high pervasiveness of perceived gender-role stereotypes with no significant gender difference in perceiving gender-role stereotypes during employment. the socioeconomic factors, except income, have predicted participants’ perception of gender-role stereotypes significantly. it implies,females are more prone to pursue masculine roles than males pursue feminine roles. it requires gender sensitization, particularly for males to build understanding of gender neutral career attainment. key terms: gender stereotypes, gender-inappropriate role, perceived gender-role, perceived employment opportunity introduction 1.1 background this study is aimed at investigating students’ perception of gender-role stereotypes (pgrs) and associated factors. gender-based early skill training traditions in ethiopia included cultural instructions to boys and girls by parents. mothers give traditional home-based skill training and education to girls. fathers give traditional skill training and knowledge on agricultural tasks to boys in the rural. urban fathers instruct boys on hand crafts (teklehaimanot, 1999). however, society values the traditional skill training negatively and the skilled craftsmen are given low social status (teklehaimanot, 1999). this situation might have a carryover effect on the modern skill trainings in the technical and vocational schools of the country that had been working since 1940’s.the curriculum of the then modern technical and vocational education was organized and taught based on gender difference (moe & fine arts, 1944), until its reorganization in the year 2002. it involved purposeful gender differe ntiation in designing courses for boys and girls. as related to early traditions of career attainment, there was perception of the study fields in the tvet schools as “gender-appropriate” and “gender-inappropriate.” for the purpose of this study, the traditional “gender-based,” grouping of the tvet study fields was used. the “gender-appropriate” study fields for females were related to home science, secretarial science and nursing. the “gender-appropriate” study fields for males were related to technical and agricultural areas.the“genderneutral” study fields were related to business areas (moe, 1973; writer’s observation during pre-pilot survey at tvet school, april, 2008). 1.2 statement of the problem it has been observed that tvet colleges face problem of admitting students to the traditionally “female study fields or male study fields.” currently, there is no investigation made onthe tvet collegestudents’ perception of gender role stereotypes related to their study fields in ethiopia. therefore, here are the basic research questions addressed in this study: 1. what is the magnitude of perceived gender-role stereotypes of the respondents? 2. which elements of the socioeconomic factors bring about significant variance in the students’ perceived gender-role stereotypes? 3. which one of the genders is affected by perception of genderrole stereotypes more than their counter part? 1.3 objectives of the study the major objective of the study is to investigate the magnitude of the tvet school students’ perceived gender-role stereotypes and factors associated to this effect. the specific objectives are to: 1. determine the magnitude of the incidence of female and male students’ perceived gender-role stereotypes (pgrs) 2. identifythose socioeconomic factors varying significantly with pgrs. 3. identify if males or females are favored by the condition of pgrs than their counter part 1.4 significance of the study the result of this study may provide evidence on the extent of pgrs. policy makers, curriculum designers, and teachers may use the evidences to revise tvet implementation strategies. it can be used as a base-line survey to conduct research on the issue of gender role perception about tvet. 1.5 scope of the study this study is delimited to the investigation of the magnitude of first year tvet school students’ pgrs and factors related to this effect. literature review the prevailing societal and individual attitudes towards gender roles for boys and girls are more of traditional as cited in canadian apprenticeship forum consultation report (january, 2004). in ethiopia, culturally girls and boys have segregated job orientation (teklehaimanot, 1999). role divisions based on gender had been widely exercised in ethiopia, at the disadvantage of women. traditionally, in ethiopian tvet schools, boyswere trained in technical (handicraft) courses and girls were trained in domestic sciences (girmazewdie, mehari haile, and nigatufantaye, 1994). similar practices are also observed among societies’ of the world in perceiving males and females as different in roles. for example, findings in india indicate a wide gender gap in education, skill development, and upward mobility (sakhi resource center for women, 2007). as stated in the same document, compared to men’s attainment of these opportunities, the society of india gives low value to women in all socioeconomic opportunities. india exhibits a gender development index (gdi) of 0.591 (as of 2005 survey) which fitzenbergery and kunze (2005) argued that women suffer the double deprivation of overall achievement in human development. methods 3.1 research design the general research design employed for this study was descriptive survey research method. participants and sampling design the study participants were first year students admitted to the regular program of all government tvet ccolleges of oromia during 2008/09 academic year. multistage sampling design (including simple & stratified random sampling techniques) was used to obtain 310 participants (160 females, 150 males) out of the 9707 total population (6506 females and 3201 males) tvet students in oromia regional state. the sample tvet colleges were adama, ambo, bishoftu, fiche, and metehara tvet colleges. 3.2 data collection tools questionnaire items used were: individual data form used to obtain demographic data, likert-type scale, named pgd scale, used to measure pgrs, and additional items of closed and open types. 3.2.1 standardization of the scale content validity of the scale was estimated using lawshe’s (1975) statistical method of estimating content validity ratio(cvr). the cvr result was 0.87. analysis of pilot test data resulted in cronbach alpha valueof 0.88 reliability estimate for the scale items. five response options were assigned for the scale items. the scores were made to range from 1 to 5. the highest score indicated high magnitude of pgrs. 3.3 methods of data analysis the statistical techniques used to analyze the data were descriptive statistics, t-test, analysis of variance and stepwise multiple regression. the spss 15.0 for windows was applied for this purpose. results and discussion 4.1 perceived gender-role difference the age ofthe respondents ranged from 15-34 years. the majority of the respondents were within 15-18 and 1922 age groups. the average age was 18.49 (sd = 1.64). analysis of the data on pgd scale indicates moderate pervasiveness of perceived gender role stereotypes (pgrs) for the total respondents, x = 118.the maximum and minimum scores are 188 and 55, respectively.themaximum possible score is 200 as indicated in t-test indicates statistically significant difference between female and male respondents.the descriptive statistics in table 2 displays that both male and female respondents in gender appropriate study fields (tsfs) had reflected pgrs. table 1: descriptive statistics and t-test valuefor scores on pgd scale by gender table 2: descriptive statistics for scores on pgd scale by tsfs and gender the anova summary in table 3 explains that f value for the main effect, study fields is statistically significant. gender has no statistically significant influence. the difference among students in different fields of study is statistically significant on pgd measure. s e x n x sd min max t p f 160 116 22 55 182 m 150 120 22 61 188 t 310 118 23 55 188 2.6 .01 study field female male n x n x sd tfsf 65 114.65 22.60 15 112.57 23.34 tmsf 54 119.90 21.72 97 120.91 20.66 sftcb 41 113.24 21.66 39 122.73 22.95 total 150 116.04 22.17 141 120.54 21.65 tfsf = traditionally female study fields; tmsf= traditionally female study fields; sftcb= study fields traditionally common to both genders table 3: summary of anova for data on pgd scale by tsfs and gender the f-ratio for interaction effect between gender and study fields is not statistically significant. f-test for the between groups mean score differences is statistically significant. this finding is similar to the finding in lavy (2008) that male subjects were more normative and stereotypical in their thinking about the study fields. 4.2 parental education as a factor male respondents from educated fathers were more normative compared to female respondents. the overall mean scores on pgd scale is highest for respondents whose fathers had diploma and lowest for respondents whose fathers had primary education. table 4: anova summary for pgd scale data by mothers’ education and gender the main effect mothers’ education has statistically significant association with respondents’ mean scores. the main effect gender could not bring significant differences in the respondents’ mean scores. the interaction of gender with mothers’ education is not significant. the mean difference in the overall mean scores for the between groups effect in relation to mothers’ education is only slightly significant. f -ratio for source sum of squares df mean square f p study field 3373.833 2 1686.916 3.546 .029 gender 880.061 1 880.061 1.850 .174 gender by study field 2580.719 2 1290.360 2.712 .067 between groups 4169.867 2 2084.934 4.348 .013 within group 295893.738 617 479.568 total 300063.605 619 source sum of squares df mean square f p mothers’ educ 6531.533 5 1306.307 2.777 .017 gender 173.191 1 173.191 0.368 .544 mothers’ educ. by gender 5307.598 5 1061.520 2.256 .047 between groups 5414.569 5 1082.914 2.257 .047 within group 294649.000 617 479.884 total 300063.600 619 the main effect, fathers’ education is statistically significant. the f-ratio is statistically highly significant for the main effect, gender (see table 5). table 5: summary of anova for data on pgd scale by fathers’ education and gender the f ratio is statistically significant for the effect of two-way interaction between fathers’ education and gender. the f-test for the between groups mean differences resulted in statistically non significant value for the overall mean scores across fathers’ educational levels. 4.3. parental occupation as a factor the highest mean score on pgd is of the respondents from mothers of professional employee. however, respondents of mothers with no job also had relatively high scores. conversely, subjects with the lowest mean score were from day laborer mothers for both female and male respondents. respondents whose fathers had no job have the highest mean score. among the male groups those respondents from professional fathers had the highest mean score. female respondents with the lowest mean score were from day laborer fathers. male respondents with the lowest mean score were from merchant fathers. on the other hand, the analysis of variance indicated statistically significant mean difference for the main effect, mothers’ occupation (see table 6). the main effect gender also had a statistically significant f ratio. however, no significant interaction effect was observed. table 6: summary of anova for scores on pgd scale by mothers’ occupation and gender source sum of squares df mean square f p fathers’ educ 5984.073 5 1196.815 2.542 .027 gender 4027.703 1 4027.703 8.555 .004 fathers’ educ. by gender 541 9.938 5 1083.988 2.302 .043 between groups 5329.705 5 1065.941 2.257 .047 within group 294638.100 613 480.649 2.218 .051 total 299967.800 618 source sum of squares df mean square f p mothers’ occupation 6641.564 5 1328.313 2.804 .027 gender 2285.584 1 2285.584 4.825 .004 mothers’ occupation by gender 2124.481 5 424.896 0.897 .043 between groups 5756.728 5 1151.346 2.402 .047 within group 294306.877 614 479.327 total 300063.605 619 one-way anova resulted in a statistically significant f-ratio. post hoc test for the six groups of respondents in terms of mothers’ occupation was statistically non significant. the significant main effects imply that mothers’ occupational status had meaningful effect on the respondents’ variation in pgrs. the analysis of variance of scores by fathers’ occupation and gender did not yield in any statistically significant f ratios for both main effects and the interaction effects tested (table7). table 7: summary of anova for data on pgd scale by fathers’ occupation and gender application of one-way anova resulted in non significant mean differences. this implies that change in fathers’ occupational status had no relation with change in the respondents’ pgrs. 4.4 parental income as factor the data on parental monthly income is obtained through self report items included in the questionnaire (table 8). the table reveals that female respondents whose parents’ monthly income was within the range of birr 501 1000 had the highest mean score. female respondents with the lowest mean score were from parents whose monthly income was birr 2001 and above. females’ mean scores on pgd scale progressively decreased from low income parents to high income parents. this trend explains that female respondents from well-to-do parents are less sensitive to pgrs as compared to female respondents from lower income parents. for male respondents, no pattern is observed. table 8: descriptive statistics of data on pgd scale by parental income and gender source sum of squares df mean square f p fathers’ occupation 3660.836 5 732.167 1.551 .172 gender 600.053 1 600.053 1.271 .260 fathers’ occupation by gender 4331.442 5 866.288 1.835 .104 between groups 2088.200 5 417.640 0.869 .502 within group 293314.071 610 480.843 total 295402.271 615 income female male n x sd n x sd 500 & below 30 116.10 21.05 34 120.64 25.58 501 – 1000 52 117.23 24.49 40 115.48 21.99 1001 – 1500 22 116.57 18.81 24 124.94 20.40 1501 – 2000 26 115.47 20.16 21 118.00 16.39 2001 & above 30 113.67 23.50 31 125.65 19.38 total 160 115.97 22.17 150 120.56 21.65 fratio for the main effect, income, is statistically significant. the main effect, gender is statistically non significant for variation of the respondents in responding to pgd scale. table 9: summary of anova for data on pgd scale by parental monthly income and gender the f-ratio for interaction effect between income and gender was statistically non significant. moreover, oneway anova resulted in statistically non significant fratio. this result partly contradicts with salam’s (2007) finding that socioeconomic status has contribution to his subjects’ attitude towards gender-roles. source sum of squares df mean square f p income 1665.308 4 3794.557 7.934 .005 gender 3794.557 1 416.327 0.870 .481 income by gender 3874.282 4 968.570 2.025 .089 between groups 1721.798 4 430.449 0.887 .472 within group 296673.838 611 485.555 total 298395.636 615 conclusions the data analyzed justifies that perception of gender role stereotypes was moderately pervasive for both female and male respondents. the respondents conform to the traditional norm of gender role stereotypes. pgrs has statistically significantly different for female and male respondents. pgrs, in general, and conformity to gender role stereotyping, in particular, is decreasing for females. males show resistance to change their mind. it means males are more normative than females in maintaining the statuesque of males’ dominance in the social roles. it implies wider gap between the current education and training policy issues, the strategy of training, thinking level and practices of students, parents, employers and other social agencies. parental education influences tvet students’ perception of gender role stereotypes moderately. mothers’ education has some relationship with the students’ perception of pgrs but influences females and males differently. comparatively, fathers’ education relates to students’ pgrs more than mothers’ education does. a specific finding worth mentioning is that male subjects whose fathers are better educated experience pgrs in employment more as compared to female subjects from fathers of the same educational level. the socioeconomic factors, except income, have predicted perception of gender-role difference highly significantly for both male and female groups. it was generalized that females were more prone to pursue masculine roles than males pursue feminine tasks. recommendations the objectives achieved in this study helped to recommend the following: 1. ethiopia has a promising policy to achieve the objective of gender equality through tvet for career attainment. it needs gender sensitization practices to alter the current biased perception of jobs as genderappropriate/ gender-inappropriate” from the mind of the society. 2. there should be attitude change through provision of community based education and guidance services aimed at disclosing the societal tradition of limiting social roles to either male or female group. 3. in order to minimize the number of unemployed female and male graduates of tvet schools, gender neutral job attainment ideology should be inculcated. 4. automation of the traditional manual labor in the home science fields and the industrial fields requiring physical strength enhances attainment of societal norm of gender neutral career aspiration. 5. labor market of all occupations should invite both females and males at equal ease in terms of work conditions. 6. for the required paradigm shift of the traditional culture of gender-based career attainment to modernized culture of gender neutral career attainment tvet program organizers of all levels, have to work on creating awareness and in developing positive attitude toward equality of all jobs. 7. detailed investigation has to be made in order to identify why educated fathers and well to do parents tend to preserve the traditional gender-role stereotypes. references canadian apprenticeship forum (2004): accessing and completing apprenticeship training in canada: perceptions of barriers, consultation report. january 2004. fitzenbergery, b. and kunze, az. (2005): vocational training and gender: wages and occupationalmobility among young workers. girmazewdie, et al. (1994): the training and placement of vocational secondary school teachers in ethiopia,the ethiopian journal of education, 15, (2), 1-32. ier, addis ababa university. howitt, d., & cramer, d. (2005): introduction to spss in psychology for spss 15, prentice hall, pearson education limited. lawshe, c. h. (1975): a quantitative approach to content validity. personnel psychology, 28, 563-575. lavy, v. (2008): do gender stereotypes reduce girls’ or boys’ human capital outcomes? evidence from naturalexperiment.journal of public economics.the hebrewuniversity of jerusalem, royal holloway university of london, cepr and nber. moe & fine arts (1973): annual reports from tegbare’d, addis ababa. institute of ethiopianstudies(ies). moe & fine arts (1944): compiled documents ofmunites and reports. institute of ethiopian studies (ies). sakhi resource center for women (2007): review of literature on women’s plan inkerala. convent road, trivanrum35 .http://sakhikerala.org/downloads/review%20of%20literature%20of%20w%20&%20devt..doc teklehaimanothaileselassie (1999): the cultural foundation of ethiopia, ier flambu, 7,1,1-10. http://sakhikerala.org/downloads/review%20of%20literature%20of%20w%20&%20devt..doc perceptions of students and instructors toward effective teaching practices: the case of selected universities in ethiopia dr. birhanu moges adama science and technology university school of educational sciences and technology teacher education department of psychology tel: +251-911-99-59-10 e-mail:abirhanumoges@yahoo.com abstract the purpose of this study was to explore perceptions of students and instructors toward effective teaching practices in selected universities of ethiopia. to conduct the study, a mixed research method was employed. the study was conducted in four experienced universities and the data were collected from 69 students and 64 instructors of the sample universities. in selection of the sample population, systematic and random sampling techniques were used. the main instruments of data collection were interviews and questionnaires. the data were analyzed using percentage, mean and standard deviation. the findings of the study revealed that instructors and students have positive perception toward effective teaching. effective teaching was regarded as respectful, interesting, and caring about students’ success. good teachers were regarded as those who are friendly, love their subject, encourage questions and discussions, are fair in their evaluation, well prepared and organized, and make difficult subjects easy to learn. the findings also showed that, by contrast, ineffective instructors are unplanned, unknowledgeable, unapproachable, boasting, and biased in their evaluation of their students’ performance. finally, recommendations were forwarded based on the major findings so as to minimize the problems observed and maximize the implementation of effective teaching. key words: effective teaching, instructors, perceptions, practice, universities. introduction the government of ethiopia has placed great emphasis on quality education and effective teaching. it recognizes effective teaching as an essential component for development needs of the society. effective teaching and learning require the use of different methodologies and strategies to meet the demands of the students. the recent policy of quality improvement focuses on the complex interaction that takes place in the teaching-learning process at the university level to emphasize effective teaching (moe, 2005). when students’ and teachers’ perceptions towards effective teaching are analysed, it is found out that they vary regarding their perspectives of effective teaching: some are concerned with student-centered issues such as motivation and classroom climate while others have made their concerns on instructional and management techniques (tootoonchi, lyons & hagen, 2002). in this study, the focus is based on perceptions of students and instructors toward effective teaching practices. effective teaching is lecturing that creates an environment in which deep learning outcomes for students are made possible, where high quality student learning is promoted and where superficial approaches to learning are discouraged (hay, 2000; raymond, 2001; witcher, onwuegbuzie & minor, 2001). the characteristics of effective teaching based on personality view encompass personal human qualities such as intelligence, selfconfidence, fairness, respect, caring, sensitivity, flexibility, enjoyment of students, openmindedness, friendliness, providing individual attention, kindness, enthusiasm, having a good sense of humour, making learning interesting, being serious, being hospitable towards students, teaching style, trust, credibility, and even teacher attractiveness and height (oredbeyen, 2010; okpala & ellis, 2005). regarding ability characteristics, researchers believe that effective teaching can be defined in terms of an embarrassment of skills and behaviours (efficient, reflective, insightful), knowledge (content, pedagogical, social, tacit knowledge), and experience of good teachers (beishuizen, hof, vanputten, bouwmeester, & asscher, 2001; berk, 2005; cheng, mok, & tsui, 2001; raymond, 2001). effective teaching is an art and not an easy endeavour. recent findings shed light on two characteristics of effective teaching: their personality and their ability. from the personality perspective, an effective teaching is the one which demonstrates “… closeness, warmth, and enthusiasm (immediacy) … perceived physical and psychological closeness of the instructor to the student …” (walls, nardi, vonminden & hoffman, 2002:40). from the ability perspective, the crucial factors of effective teaching are being skilled, knowledgeable and experienced (beishuizen, et al., 2001; hay, 2000). effective teaching knows how to create an effective learning environment by being organized, prepared, and clear (cheng, et al, 2001; torff, 2003; walls, et al., 2002). therefore, the main objective of the present study was to assess perceptions of students and instructors toward effective teaching practices, with the intent of comparing their responses to cross cultural descriptors provided in empirical studies. statement of the problem education systems seek to provide instructors with opportunities for on-going professional development to fully prepare them for their effective teaching and to retain a high-quality instructor workforce. this study examined the take-up of professional development, that is, the degree of unsatisfied demand for effective teaching and the factors that support or hinder meeting development needs. the belief of instructors and students shows that strong university-level evaluation tends to nurture and improve effective teaching, which in turn can lead to improvements in the quality of education. this is true not just for evaluation in general but for specific aspects of effective teaching such as teaching students from diverse backgrounds. this study was conducted on engineering instructors and students because this field is given emphasis by the government. the researcher has observed students complaining frequently about their instructors being ineffective. instructors’ perceptions, practices and attitudes are important for understanding and improving educational processes. the researcher focused on examining a variety of these issues which previous research has shown to be relevant to effective teaching practices. in addition, the differences between instructors’ and students’ views regarding effectiveness and characteristics of instructors and experiences have inspired the researcher to conduct this study. the researcher decided to explore perceptions of effective teaching practices because instructors’ and students’ perceptions and beliefs can lead to change and improvement. objectives of the study this study was aimed to respond to issues with regard to engineering education at selected universities in ethiopia. in particular, the study has attempted to:  explore the relationship between effective teaching and the instructors’ personality and ability;  assess students’ and instructors’ perceptions of effective teaching practices;  examine predominant instructors’ characteristics perceived by the study participants to describe effective teaching;  identify whether instructors’ characteristics have any effects on effective teaching;  provide useful information to instructors on teaching approaches and instructor characteristics that affect effective teaching. accordingly, this study is designed to address the following questions: 1. what are students’ and instructors’ perceptions of effective teaching? 2. to what extent are students’ perceptions of effective teaching similar to those of instructors? 3. to what extent are students’ perceptions of ineffective teaching similar to those of instructors? 4. are the descriptors used to describe effective teaching focused more on the ability or on the personality view? significance of the study the results obtained and implications drawn could be beneficial to instructors who are receiving students from all corners of the country to better understand the needs of students from another culture in the classroom environment. in addition, the researcher considers this work as a helpful guide to those who are involved in the development of future research on similar settings. in view of the above, this study will help university instructors, students, academic department heads, deans, the ministry of education, the regional education bureaus and other concerned bodies to design preventive and rehabilitative measures regarding problems influencing successful implementation of effective teaching practices and instructors’ characteristics in engineering education. definition of the terms effective teaching/instructor– is synonymous with, successful, outstanding, expert, good, above average, superlative, and superior teaching. other ‘criteria’ used throughout this study is the synonymous terms effective/excellent teaching and teaching excellence/effective. perception: the view/feeling of instructors or students on the implementation of active learning. personality traits – can be described as the inherent skills each unique, individual human being possesses inside. examples would include passion for one’s subject matter, sensitivity to students’ needs and friendliness to students. ability skills – can be described as learned or practiced cognitive and psychomotor skills such as the ability to operate a computer or an overhead projector, or the ability to effectively relate difficult theoretical topics to real-life examples. instructors’ characteristics –an effective university level instructor is one who demonstrates closeness, warmth and enthusiasm; perceived physical and psychological closeness of the instructors to the students. effective instructor is being skilled, knowledgeable and experienced in teaching-learning activities. experienced university: in this study, it includes university, which service more than 20 years. perceptions: it includes attitudes of instructors and students toward effective teaching. materials and methods research design a mixed-method approach using a survey design for obtaining descriptive statistics supported by a qualitative investigation was employed because of the complexity of the research issues. further, the researcher primarily selected descriptive survey method because it is found to be the most appropriate technique for collecting vast information and opinions from quite a large number of respondents (creswell, 2009). sampling techniques the sample universities (adama, addis ababa, haramaya and hawasa) were conveniently selected, for the researcher had contact persons for easy data collection. the sample for this study was selected using systematic and random sampling techniques. sources of data the primary sources included in this study were engineering students and instructors, deans and vice deans, and department heads selected from the four experienced sample universities. the secondary sources for the present study were printed materials. sample size and sampling procedures according to the information obtained from the sample universities, a total of 690 fourth year students and 106 instructors were available in the universities. accordingly, 69 or one-tenth of the senior year engineering students and 64 or three-fifth of the instructors were included in the study. in order to secure additional information, three classes were observed three times. furthermore, the three observed instructors and three students were interviewed. all together, 68 students and 64 instructors were included in the study. instruments three main instruments of data collection, namely, questionnaire, classroom observation and interview were used in the study. questionnaire: the questionnaires were prepared and completed by engineering instructors and students. the questionnaires implemented a four point likert scale with the following meanings: 1=not important (ni), 2= somewhat important (si), 3= important (i), 4= very important (vi). the questionnaires had three parts. the first part of the questionnaire was intended to gather background information of the instructors and students. the second part of the questionnaire consisted of items that intended to examine instructors’ and students’ perception of effective teaching. the third part was about the practices of effective teaching strategies. the researcher validated the instruments that were developed as follows. before the actual data collection, the instruments were given to colleagues so as to get valuable comments and criticisms on the strengths and weaknesses of the items. based on their comments, necessary modifications were made and given to the thesis advisor for further comments, criticisms and evaluation. then, the instruments were tried out in small-scale study that was undertaken in a similar university. the total number of participants in the pilot study was 5 instructors and 15 students. after administering the instrument, some participants were asked for feedback. based on their feedback, some of the questions were refined. the reliability of the instruments was tested by cronbach alpha method. the computed reliability of the instruments was 0.81. thus, the instruments were found reliable to collect data for the main study and then administered as scheduled. classroom observation: observation in the actual classroom teaching and learning process was used as data gathering instrument. for the purpose of observation, checklist was employed. based on this, the three selected classes were observed three times each. hence, a total of 9 observations were marked using the checklist developed for the purpose. the observations were focusing on instructor-student interaction in relation to effective teaching, classroom facility, student population in the classroom, instructors’ and students’ activities. interview: to supplement the data obtained through questionnaire, the researcher conducted interviews with department heads, deans and students using openended questions, which are related to knowledge and practices of effective teaching. procedures: the researcher adopted three steps in collecting the data for the study. first, relevant literature was reviewed to get adequate information on the topic. second, objectives and research question were formulated to show the direction of the study. third, data gathering tools were developed and piloted. after the questionnaire had been distributed and collected, classroom observations took place. finally the interview with instructors and students was conducted. methods of data analysis the data collected through different instruments (questionnaires, observations and interviews) were organized, presented in tables and then analyzed statistically using statistical methods. presenting likert scale is of benefit in understanding the results since all judgments and comparisons are based upon it. means, ranks, standard deviations and minimum/maximum counts were derived for each individual question. this data was then manually collapsed and average rating comparisons were made between how the four population groups rated personality and ability measures. results and discussion research question one: what are students’ and instructors’ perceptions of effective teaching? since the questionnaire items were categorized under two separate categories of effective teaching characteristics (personality and ability), the results are presented in two different tables (table 1 for personality & table 2 for ability) and addressed in separate sub-sections. in describing effective teachers, respondents identified six personality characteristics that were perceived ‘very important’ (vi): effective instructors are respectful of their students (m=3.73); make classes interesting (m=3.70); are fair in grading and evaluating student work (m=3.67); care about students’ success in their course (m=3.56); show that they really like the subject they teach (m=3.53), and are friendly to students (m=3.50) (see table1). also worthy of mentioning is the fact that all remaining personality characteristics of effective instructors were perceived by the respondents to be ‘important’ (i). thus, each one of the 11 personality characteristics specifically designed for the questionnaire was rated either ‘very important’ or ‘important’. this indicates that all personality characteristics that make effective teaching reflected by the respondents were essential (average mean of 3.37, table1) to the entire sample population to describe effective teaching. table 1: personality traits measure of effective teaching by entire sample (α=0.05) personality characteristics min max mean(m) rate s d rank . … are respectful of their students. 1 4 3.73 vi 0.538 1 . … make classes interesting. 1 4 3.70 vi 0.522 2 . … are fair in grading and evaluating student work 1 4 3.67 vi 0.612 3 . … care about students succeeding in their course. 1 4 3.56 vi 0.632 4 . … show that they really like the subject they teach. 1 4 3.53 vi 0.713 5 . … are friendly to students. 1 4 3.50 vi 0.735 6 . … welcome students’ opinions/ suggestions. 1 4 3.38 i 0.682 7 . … are available to help students outside of class. 2 4 3.33 i 0.693 8 . … use humour in the classroom. 1 4 3.33 i 0.781 10 . … make an effort to get to know their students. 1 4 3.11 i 0.794 10 . … have a unique teaching style. 1 4 3.11 i 0.049 11 average of means 3.37 thus, instructors’ and students’ perceptions towards effective teaching closely matches the high (2nd place) ranking of feldman’s trait “is concerned with, is friendly to and respects students” and matches the results from studies conducted by other researchers (saafin, 2005; raymond, 2001). as seen in the literature review, other researchers also report that instructors must demonstrate respect for their students from the moment of first encounter for effective teaching to transpire (colker, 2008; day, 2004 & hay, 2000). respect for students emerged as the highest trait mentioned in the qualitative, open-ended portion of the questionnaire. the importance of this trait to effective teaching has been discussed methodically in the literature reviewed (beishuizen et al., 2001; day, 2004; miller, et al., 2001; raymond, 2001; saafin, 2005). the fourth highest rated personality characteristic of effective teaching emerged from this study was “caring about students succeeding in their course” and it was also ranked the fourth highest, according to the open-ended question of the survey instrument. students ranked this trait as their second most important indicator of teaching effectively. making a link between this study’s results and the literature, borich (2000) describes effective instructors are those who “… provide a warm and encouraging classroom climate by letting students know help is available”. following on from the previous findings, students rated this trait as their premier characteristic, while the more experienced, more independent students ranked this item 6 th of the eleven personality characteristics measured in the questionnaire (berk, 2005 & cheng et al., 2001). according to the study, three ability attributes emerged as dominant (very important) by the study participants to describe effective teachers: they encourage students’ questions and discussion (m=3.70); are always well prepared and organized (m=3.60); and make difficult subjects easy to learn (m=3.50). table 2: descriptive statistics of the ability characteristics measure of effective teaching by entire sample (α=0.05) ability characteristics min max mean rate s d rank . … encourage students’ questions and discussion. 1 4 3.7 vi 0.62 1 … are always well prepared and organized. 2 4 3.6 vi 0.62 2 … make difficult subjects easy to learn. 1 4 3.5 vi 0.69 3 … have expert, up-to-date knowledge of their subject. 1 4 3.4 i 0.73 4 … require students to think critically. 1 4 3.4 i 0.69 5 … expect students to become independent learners. 1 4 3.3 i 0.73 6 … give frequent feedback about student progress. 1 4 3.2 i 0.71 7 … encourage students to learn in pairs/groups. 1 4 3.0 i 0.89 8 … maintain strict control over the class. 1 4 2.8 i 0.78 9 … use the latest computer technology in their teaching. 1 4 2.5 i 0.98 10 … give many quizzes and tests. 1 4 2.3 si 0.81 11 … have many years of teaching experience. 1 4 2.2 si 0.96 12 … assign a lot of homework. 1 4 2.0 si 0.74 13 … lecture (talk) for the entire class period. 1 4 1.7 si 0.87 14 average of means 2.89 results from the open-ended question also indicate the importance of being prepared for instructors to deliver well-organized materials and lessons to their students. the literature review meta-table ranks this practice as the 4th most important (“explains using simple terms”) and shows it was important to preceding researchers (barnes & lock, 2010; walls et al., 2002). research question two: to what extent are students’ perceptions of effective teaching similar to those of instructors? even though numerous matches appeared amongst the respondents regarding effective teaching, some minor mismatches did surface. table 3: major matches between instructors and students in descriptors used to describe effective teaching personality characteristics of effective teaching student rating instructor rating make classes interesting vi vi are respectful of their students vi vi are friendly to students vi i care about students succeeding in their course vi vi show that they really like the subject they teach i vi are fair in grading and evaluating student work i vi are available to help students outside of class i i welcome students’ opinions/suggestions i i make an effort to get to know their students i i have a unique teaching style i si use humour in the classroom i i both group of respondents (students & instructors) consider making classes interesting, being respectful of students, and caring about students’ success to be ‘very important’ (vi) or predominant characteristics of effective teaching (table 3). furthermore, both respondents share the perception that effective teaching is exhibited by instructors who remain available to students outside of class, who are open to students’ input, who make efforts to learn their students’ names, and who employ appropriate humour in the classroom. three other personality items– being friendly to students, demonstrating that they like their subject, and being fair when dealing with students – were also considered as either ‘important’ or ‘very important’ to both groups. this once again suggests a high degree of similarity in their opinions of what constitutes effective teaching (cheng et.al. 2001; oredbeyen, 2010). both respondents (students & instructors) consider effective instructors to be always well prepared for their classes and have the ability to make difficult topics easy to learn (table 4). despite this finding, however, it can be reasonably concluded that student and instructors perceptions of what constitutes effective teaching are to a large extent very similar. other sub-group differences which have emerged will be discussed below. table 4: major matches between instructors and students in descriptors used to describe ability characteristics of effective teaching ability characteristics of excellent teaching student rating instructor rating are always well prepared and organized vi vi make difficult subjects easy to learn vi vi have many years of teaching experience i si encourage students’ questions and discussion i vi have expert, up-to-date knowledge of their subject i i require students to think critically i vi give frequent feedback about student progress i i expect students to become independent learners i i maintain strict control over the class i i encourage students to learn in pairs/groups i i i use the latest computer technology in their teaching i si give many quizzes and tests i si lecture (talk) for the entire class period si ni assign a lot of homework si si to support the data from the questionnaire and to better understand the characteristics of effective teaching, the interview questions were used and elicited responses such as: s1: in my opinion, an effective teacher is the one who is strict and controls the class, has a unique teaching style, and gives many quizzes or tests. s2: an effective instructor gives many tests and frequent feedback to students. instructors, on the other hand, rated the ability characteristics of requiring students to become critical thinkers, encouraging questions and discussion as well as expecting students to become independent learners as ‘more important’ than did their young charges who are likely to be inexperienced with these concepts of higher education. responses to the open-ended questions in the questionnaire help us to understand instructors’ perspectives of these attributes: in1: an effective instructor should regularly succeed in inculcating a love of knowledge. in2: an effective instructor is one who understands the student needs and learning preferences and, thus, can facilitate high-order thinking in the learning process. relative to how instructors assess encouraging students’ questions and discussion, as well as to the importance of assisting students to become independent learners, instructors had this to say: in1: an effective instructor is one who is always open-minded–who actually welcomes students’ questions, opinions, and suggestions, and one who uses what students say and contribute to bringing the learning process to life! in2: … listen to them, have time for students outside of class, be creative and fun in class, be a friend and an instructor. in3: the ability to motivate students to learn. thus, findings from this study appear to correspond with what beishuizen et al. (2001:185) found in their study conducted in the netherlands. similar to students in this study, primary students in holland “… described effective instructors primarily as competent instructors, focusing on transfer of knowledge and skills …” whereas secondary students and instructors at the same institute in leiden “… emphasised relational aspects of effective instructor …” reflecting what has just been discussed with the instructors’ comments. furthermore, “young students displayed an ability view while mature students and instructors showed a personality view on instructors” (beishuizen et al., 2001:196). finally, a comparison of the significant differences between the students and instructors views indicate that instructors rated six ability characteristics to be more important indicators of effective teaching than did their students. instructors would more likely describe the effective instructor as one who requires students to think critically, encourages students to work in small groups or in pairs, gets to know their students, and encourages students’ discussion and questions. to help us identify with the environment at the time the study was conducted, the following quotes taken from the open-ended qualitative questions are presented: in1: someone who can get the students to question ideas/concepts –create a genuine interest in learning. someone that “pushes” the students to do their best. in2: student-centered learning manoeuvres that guide students to independent knowledge and skills acquisition. in3: … engage the students in critical thinking and new ways of looking at the world & their learning who then reflects on the process & seek ways to improve. in4: interact with students on a professional and personal level. students, on the other hand, would place more emphasis on ability descriptors of effective instructors such as being current with the latest technology and up-to-date with their subject knowledge. as it has seen in the literature review, opportunities to work in groups were also reported as a learning preference by students according to saafin (2005), and raymond (2001). research question three: to what extent are student perceptions of ineffective teaching similar to those of instructor? to answer this question, descriptive data that was collected through interviews and respondents’ answers to an open-ended question of the questionnaire was compared. information extracted from interviews and open-ended question, it can be observed that students’ and instructors’ perceptions of ineffective teaching coincide with regard to a number of attributes. both groups describe the ineffective instructor as someone who does not respect his/her students, does not care, is boring, can not explain the subject matter well, is unprepared for class and is unfair in grading . table 4.5 below, which compares the characteristics of effective teaching extracted from research question alongside the results of the ineffective instructor revealed from the interviews and open-ended question, suggest that at least to the population sampled in the selected universities, ethiopia, there is agreement that study participants do view the two extremes as polar images of each other. table 5: a comparison of effective and ineffective teaching characteristics effective instructors (results of research question 2) ineffective instructors (results of research question 3) are respectful of their students are disrespectful of students care about students succeeding in their course don’t care if students understand make classes interesting are boring make difficult subjects easy to learn cannot explain well are always well prepared and organized are unprepared for class are fair in grading and evaluating student work are unfair in grading note: personality measures are highlighted in italicized bold font. the first descriptor of the ineffective instructor to emerge from table 5, above is disrespectful of students. this finding is particularly interesting for three reasons. first, it represents a very close match in that it appeared with nearly the same frequency in both students’ and instructor’s data from the open-ended question. second, supportive evidence is provided for researcher earlier argument in favour of the mixed-methodology approach to the questionnaire instrument wherein it was claimed that unforeseen and beneficial results can often be revealed by the use of qualitative methods. third, it was indeed an unexpected result since the researcher had not anticipated that lack of respect would be an issue raised by students in answering the open-ended question, especially in the level where this study was conducted. an uncaring instructor would most likely meet with resistance and minimal academic performance from his or her students. however, even though researcher’s observations stem mainly from teaching experience in an ethiopia context, it appears that this characteristic is not unique to the universities. one student said: the bad instructor is not concerned about the students. researcher: what do you mean? student: i mean he/she can’t tell when someone is distracted in class because he/she doesn’t care of this guy. for me i don’t usually work hard for an instructor that has no care to me … or doesn’t ask me if i have a personal problem or not. an engineering instructor said: oh!!! to tell you the truth, i have a well developed emotional quotient(eq), so for me an ineffective instructor would be someone who didn’t show his/her emotional side … who was uncaring, frigid, unfeeling, lacked compassion … actually, it’s just the opposite of what i’ve just answered in effective instructors. researcher: are you saying that the characteristics of the effective instructors are merely the opposite of the ineffective one? instructor: essentially, yes! previous research on teaching effectiveness has established caring as an important factor in distinguishing between good and ineffective teaching. “is concerned with, and is friendly to …” have been reported by other authors as an essential personality component (saafin, 2005; walls et al., 2002). this is consistent with brookfield’s in saafin (2005) argument discussed in the literature review, that effective teaching requires the instructor to relate new concepts to something that is familiar to students. thus it can be concluded that unless an instructor can explain his/her topic in a meaningful manner, effective learning will be unlikely to transpire in the classroom or lecture hall. respondents in this study described ineffective instructor as being unprepared and disorganized. for example, saafin (2005) would all agree that effective instructors must be prepared and organized. if instructors fail to capitalize on this opportunity, students will rapidly lose interest and respect, causing the instructor to resort to wielding power in an autocratic manner in order to maintain classroom order. last in this discussion of features describing the ineffective instructor is being unfair with grades (barnes & lock, 2010). research question four: are the descriptors used to describe effective teaching focused more on the ability or on the personality view? of the 25 questionnaire items utilized to evaluate respondents’ opinions of effective teaching characteristics, 11 were purposely designed to reflect personality traits while 14 were included to measure ability characteristics. the average of means of the personality measure was calculated as 3.4 whereas the average of means of the ability category was less than 2.9. in addition, by examining column one in table 6 below which represents findings from two different sources, two of the top six ranked traits are the top ranked personality characteristics. table 6: a comparison of the six highest ranked characteristics of effective teaching across respondents (students & instructors) sources questionnaire transcribed interviews open-ended question literature review 1. are respectful of their students. 1. makes lessons understandable 1. makes class interesting/fun 1. is enthusiastic for subject/towards teaching 2. make classes interesting. 2. is friendly to students 2. is friendly to students 1. is available to help students 3. are fair in grading and evaluating student work. 2.respects students 3. really knows subject knowledge 2. is concerned with, is friendly to, and respects students 4. encourage 3. encourages 4. cares about 2. is open to students’ opinions, students' questions and discussion. students students' learning ideas and discussion 5. are always well prepared and organized. 4. makes classes interesting/fun 5. makes lessons understandable 3. stimulates interest in course/subject 6. care about students succeeding in their course. 5. makes students think 6. is well prepared for class 3. encourages students to think critically 4. is prepared, organized 4. is knowledgeable of subject 6. answers all students question 4. explains using simple terms 5. is sensitive to and concerned with class level and progress 5. is fair and impartial in marking/evaluating students 6. really knows subject knowledge 6. provides frequent, prompt, useful feedback 6. is dedicated, committed note: personality measures are highlighted in italicized bold font. it can be observed that from the transcribed interviews of study respondents, 54% of the traits mentioned by instructor and student respondents were attributed to personality measures while the remaining 46% were categorized as ability, indicating that when verbally discussing effective teaching traits, respondents in this study slightly favoured personality traits. of the two comparative measures, personality traits were indicated to be more dominant than ability characteristics when both instructor and student respondents described the characteristics of the effective instructor in the open-ended question. out of the 46 attributes which were synthesized, 71% were classified as personality characteristics while ability characteristics occupied the remaining 29% of the total characteristics extracted from the questionnaire. as can be seen from column three in table 4.6 above, personality measures occupy the top two of the first six characteristics reported in the open-ended question found in the questionnaire. consistent with the results of the questionnaire and with the transcribed interviews, personality measures are once again indicated to be the more frequently mentioned of the two by the study respondents. conclusions the findings of this study support the results of previous studies on teaching effectiveness which demonstrate that many traits or practices are common, regardless of culture, age, and/or academic discipline. results from research question one which attempted to capture predominant characteristics of effective instructors have revealed that all of the predominant personality and ability measures used by this study’s respondents to describe effective teaching coincide with principal characteristics revealed in the literature review. common personality characteristics of effective teaching therefore appear to be: demonstrating respect to students, delivering interesting classes, caring about students’ welfare, exhibiting a love for the subject being taught, and being friendly to students. common ability attributes of effective teaching are demonstrated by educators who encourage two-way communication with students, are organized and well-prepared, and present topics in ways that students can relate to and easily understand. instructors who are aware of students’ expectations and are willing to amend their behaviours based on student feedback are armed with important knowledge to dismantle walls of miscommunication. improved communication and understanding between students and instructors will enhance classroom environments, lead to higher instructors’ ratings, and knowledge transfer, improve retention of students and ultimately, boost institute reputation and image. research questions two and three examined the degree to which student perceptions of effective and ineffective instructors are similar to instructors’ perceptions. the two questions, to be discussed jointly, were included in this study to attempt to determine if differences in opinion exist at the institute under study between instructor and student respondents in their opinions of what constitutes effective and ineffective teaching. question three was purposely designed to assess respondents’ opinions to determine if mirror images of the effective instructor were held by study respondents as well as to determine effective attributes from an alternate approach. only two personality traits appear to have raised significant differences of opinion between the study’s two population groups. instructor respondents rated the use of humour in the classroom to be an essential ingredient to effective teaching in contrast, engineering students, with less developed engineering skills needed to interpret humour, understandably placed a low value on this quality. having a unique teaching style is perhaps being expressed by inexperienced students who are expecting to be entertained in the classroom or those do learn more effectively from instructors who vary their instructional delivery. this leads us to the suggestion that instructors who employ a variety of methods of communication in the classroom may concurrently improve knowledge transfer and secure higher student ratings on their assessments. the instructors’ expectation of students to interact in two-way dialogue at their university was encouraging to see, lecturing is not viewed as a favourable method of effective teaching according to both the literature results and the study’s respondents. the lower rating of this trait by students is probably once again an example of students’ inexperience with this manner of communication, and with their expectation or misconception that university classes are of the lecture format. student and instructor respondents agreed on a number of characteristics they believe distinguish the effective from the ineffective university instructor. both students and instructors regarded the effective quality to treat learners with respect and caring as very important. the respondents’ perceptions also correspond with regard to making classes interesting, caring about their students’ success, demonstrating a love for teaching and being friendly. thus, according to these study respondents, both skills and affective factors are necessary virtues to paint a portrait of the effective university instructor. as we have seen above, all of these personality and ability factors used to describe effective teaching were highly compatible with the literature reviewed for this study. conversely, instructors rated “the ability to think critically” ,”being fair in grading”, “encouraging students’ questions and discussion”, and “expecting students to become independent learners” as more important compared to the students’ rating,. from this potentially important finding and it can be concluded that instructors’ judgments of effectiveness are founded on strong pedagogical principles and the acquisition of a more global view of education learned in their professional development programs. further, according to this study’s respondents, ineffective instructors are: disrespectful of students, do not care, are boring, can not explain topics well, are unprepared for class and are unfair with their grading. what has resulted from examining the characteristics of ineffective instructors has produced mirror images of most of the traits that were considered predominant effective teaching measure by the same sample population. finally, the findings of this study conducted in the selective universities, are consistent with past researches conducted at various locations around the globe. findings support a widespread view that certain personality and ability traits are critical to effective teaching. both personality and ability characteristics are used by respondents in describing effective and ineffective teaching, with personality traits appearing to be the more important of the two. most instructor respondents appear to be aware of their students’ expectations of requisite ingredients for teaching effectiveness. recommendations based on the findings of this study, the following recommendations are made. first, induction programs for new instructors entering university, particularly engineering departments in the universities of ethiopia should include a discussion of the impact of established, objective and unalterable evaluation and grading procedures on students who might be unfamiliar with this approach. vital communications such as this could avoid potential conflict with students receiving their mid-or final semester grades, and thus improve classroom relationships. second, this study could provide university policy makers with an applicable list of effective teaching characteristics to help them design appropriate, sensitive and reliable instruments to evaluate and encourage teaching effectiveness of their instructors. since both student and instructor perspectives have been ranked in order of importance, a valid evaluation form of teaching effectiveness used by students and administrators to evaluate their instructors could be developed. if the same form is used by both administrators and students to evaluate instructors, the students’ feedbacks are more seriously consider, thereby administrators could become more enlightened as to the constantly evolving demands of the classroom environment, and thus validity of the evaluation instrument could be ensured. second, attributes of what constitutes effective teaching in the eyes of the students specific to the universities where this study was conducted could become a valuable part of recruitment and in-service offerings. providing such information and training to new and/or adjunct instructors as well as to veteran instructors with consistently low student ratings could contribute to student satisfaction and improved learning, better instructors’ performance, institute reputation for the provision of service excellence, and improved student retention. third, this study may impart valuable information to universities and curriculum program development specialists by providing them with the results of university students’ and instructors’ perspectives in universities environment to guide them in creating more effective and culturally sensitive education programs. equally important, if the attributes of what is required to be effective instructors are made available to students considering the teaching profession prior to their commitment to the program, frustration, loss of self-esteem and waste of time and money could be reduced. similarly, attrition rates from university programs could be reduced if job performance criteria were made transparent to potential instructors prior to their commitment to the program. fourth, results of this study could be used in proper preparation for instructors entering the classroom environment as an instructor for the first time could include not only what constitutes effective teaching and as well as instruction and training on how to aspire to those characteristics, but also create an awareness that student perceptions are similar to instructor perceptions and are considered in research to be valid. finally, the results of this study could also be used to develop workshops to disseminate information on what constitutes effective teaching throughout the ethiopian universities and made available to all who opted to attend. acknowledgements there are no words to express my utmost gratitude to research and publication office (rpo) for their direct contributions to this daunting project. my appreciation also goes to my 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(2001). characteristics of effective teachers: perceptions of preservice teachers. research in the schools, 8(2), 45-57. contents assessment practices in technical and vocational education and training colleges in oromia regional state ………………………………………………………...…1-15 dr. habtamu kebu and dr. kassim kimo assessment of malt barley production technical efficiency in south eastern ethiopia: stochastic parametric estimation techniques…………..…………………...…….16-30 zegeye tirfe determinants of parental school choice in adama town …………………………………..31-40 berhane simie technical and vocational education students’ perception of gender role difference……..41-53 gezahegn gurmu balcha perceptions of students and instructors toward effective teaching paractices: in selected universities, ethiopia………………………………………………………………………...54-75 dr. berhanu moges