microsoft word 1. cover pages fassil k. (mejs) volume 1 (1): 74 – 81, 2009 silicon status and its relationship with major physico-chemical properties of vertisols of northern highlands of ethiopia fassil kebede department of larmep, college of dry land agriculture and natural resource management, mekelle university, p.o.box-231, mekelle, ethiopia (fyimamu@gmail.com) abstract silicon is an essential mineral element for higher silicophile plant species and animals. literature states that one of the most important functions of si is the stimulation of plant’s defense mechanism against abiotic and biotic stresses. in addition, si fertilization has a more positive effect than liming on the chemical and physical properties of the soil. there are only a few studies in ethiopia that present silicon status of some ethiopian soils. hence this study was initiated with the objective of understanding si distribution in the soils of the northern highlands of ethiopia. to this effect, 32 soil samples were collected from five agro ecological zones of tigray. si in all the samples was determined in the laboratory of ethiopian geological survey. this study revealed that si contents ranged from 79.8 to 87.5 g si kg-1 in the cultivated vertisols of adigudom, from 97.7 to 115.2 g si kg-1in axum, from 113.7 to 117.2 g si kg-1in maychew, from 130.0 to 133.9 g si kg-1 in shire and from 137.3 to 166.3 g si kg-1in wukro. the highest concentration was hence found in wukro where the sand content amounted to 50% whereas the lowest level was obtained from soils of adigudom where the clay content exceeded 60%. the si contents in all the studied soils are lower than the documented ranges of 200 and 300 g si kg-1. significant correlation was found between silicon status and organic carbon 0.84*(p<0.05), silt 0.84*(p<0.05) and clay 0.84*(p<0.05). finally, based on the enormous role of si in plant physiology and agriculture, this study suggests commencing si fertilization in these soils for an expected increase in crop productivity. keywords: essential nutrient, silica, silicophile plant species and animals, si fertilization 1. introduction since, crop production, is the major source of food for the population and hence it is the prime contributing sector to food security in ethiopia. in addition, it plays a vital role in generating surplus capital to speed up the overall socio-economic conditions of the farmers. ethiopia is believed to have a considerable land resource for agriculture. about 73.6 million hectares (66%) of the country’s land area is estimated to be potentially suitable for agricultural production (fassil, 2002). it is generally accepted that this land resource can support a large population by providing enough food and other agricultural products required for the development of other sectors. however, the country has remained unable to feed its people for many years due to archaic agricultural practices and climate variability. mekelle university issn: 2073-073x 74 mailto:fyimamu@gmail.com fassil k. (mejs) volume 1 (1): 74 – 81, 2009 the farming systems in ethiopia can be classified into five major categories namely the highland mixed farming system, the lowland mixed agriculture, the pastoral system, shifting cultivation and commercial agriculture. the highland areas are inhabited by four-fifths of the population and also support about 70% of the livestock population. according to fassil (2002), crop production is estimated to contribute on average about 60%, livestock accounts around 27% and forestry and other sub-sectors around 13% of the total agricultural value. small-scale farmers who have been adopting low input and low output rainfed mixed farming with traditional technologies dominate the agriculture sector. as the highland’s population continues to grow rapidly, its agricultural land is becoming increasingly degraded. farmers in the highlands are intensifying land use to meet food needs without proper management practices and cost effective inputs. the resulting depletion of nutrients from soils has caused crop production to stagnate or decline in the highlands. unless a concerted effort is placed in confronting the problems of nutrient depletion, deteriorating agricultural productivity will seriously undermine the foundation of sustainable economic growth of the nation at large. silicon is the second most abundant element in the earth’s crust constituting approximately 20 atomic % of the lithosphere (iler, 1979). in soil solutions, the prevailing form is monosilicic acid, si(oh)4, with a solubility in water (at 25 ˚c) of about 2 mm (equivalent to 120 mg sio2 per liter). on average, the concentrations in soil solutions are 30-40 mg sio2 per liter range between about 7 and 80 mg) with a tendency to lower concentrations at high ph (>7) and when large amounts of sesquioxides are present in soils and anion adsorption is dominant (jones and handreck, 1967). beginning in 1840, numerous laboratory, greenhouse and field experiments showed sustainable benefits of si fertilization for rice (oryza sativa l.), barley (hordeum vulgare l.), wheat (triticum vulgare vil), maize (zea mays l.), sugarcane (saccharum officinarum), cucumber (cucumus sativa l), tomato (lycopersicon esculentum mill), citrus (citrus taitentis risso) and other crops (matichenkov and calvert, 2002). unfortunately, the present opinion about si being an inert element is prevalent in plant physiology and agriculture despite the fact that si is a biogeochemically active element and that si fertilization has significant effects on crop production, soil fertility and environmental quality (epstein, 1999; matichenkov and bocharnikova, 2000). higher plants differ characteristically in their capacity to take up silicon (marschner, 1996). depending on their sio2 content (expressed as a percentage of shoot dry weight), they can be mekelle university issn: 2073-073x 75 fassil k. (mejs) volume 1 (1): 74 – 81, 2009 divided into three major groups: wetland gramineae, such as wetland rice or horsetails (equisetum), 10-15%; dryland gramineae, such as sugarcane and most of the cereal species, and a few dicotyledons, 1-3%; and most dicotyledons, especially legumes, <0.5% (takahashi and miyake, 1977). generally, silicon has more benefits such as the mobilization of soil phosphorus (marschner, 1996), reduced water loss by cuticular transpiration, and increased resistance against lodging and pests, deserve more attention in the future in crops other than rice and sugarcane (marschner, 1996). ethiopia is a center of biodiversity where several landraces are under productivity. reasons for poor crop production in ethiopia are manifold. one of these may be nutrient depletion, elements like si. hence, the present study was carried out with the objective of auditing the current si status in agriculturally important soils of the northern highlands of ethiopia and suggest way forward with si fertilization in crop production. 2. materials and methods 2.1. soil sampling soil samples were taken from five agroecological zones of tigray, northern ethiopia. five profile pits were opened in representative sites of adigudom, axum, maychew, shire and wukro. soil samples were taken from 0-15, 15-30, 30-45, 45-60, 60-90, 90-140 and 140-160 cm depths. a total of 32 disturbed soil samples were collected. the disturbed soil samples were air dried and sieved to pass through 2 mm mesh prior to analysis. 2.2. soil analysis organic carbon was analyzed according to walkley and black (1934) method, while total n was analyzed by kjeldahl method (bremner and mulvaney, 1982) in the national soil research laboratory in addis ababa. the silicon composition of the soil samples was determined following digestion with aqua regia and perchloric acid and finally was determined using atomic absorption spectrophotometer. the silicon distribution in the soil samples was determined in geochemistry laboratory of the national institute of geological survey in addis ababa. in addition, the silicon distribution was determined by multiplying a factor 0.47 with the sio2 content that was determined in the laboratory. finally, the data were analyzed using statistical packages for social sciences (spss) 13 for windows. mekelle university issn: 2073-073x 76 fassil k. (mejs) volume 1 (1): 74 – 81, 2009 3. results as presented in tables 1-5 the si contents range in the cultivated vertisols of adigudom from 79.8 to 87.5 g si kg-1, in axum from 97.7 to 115.2 g si kg-1, in maychew from 113.7 to 117.2 g si kg-1, in shire from 130.0 to 133.9 g si kg-1 and finally in wukro from 137.3 to 166.3 g si kg-1. the highest concentration (i.e., 137.3 to 166.3 g si kg-1) was found in wukro where the sand content amounted to 50% whereas the lowest level (81.4 to 95 g si kg-1) was obtained from soils of adigudom where the clay content exceeds 60%. the pearson’s correlation was used to find a correlation between silicon status and selected soil physical and chemical properties as given in table 6. accordingly, significant correlation was found between silicon status and silt -0.85* (p<0.05) and clay 0.85* (p<0.05) for vertisols in adigudom; between silicon and total nitrogen 0.77*(p<0.05) for vertisols in axum; between silicon and sand -0.88* (p<0.05) (isn’t sand positively correlated with si under normal circumstances-check your results!) and clay -0.88* (p<0.05) for the vertisols in shire and between silicon and clay -0.85 (p<0.05). the test showed, in most cases, that there is nonsignificant correlation between si content and ph and soil organic carbon (table 6). these properties in turn determine silicon’s effect on soil fertility and plants. table 1. physical and chemical properties of vertisols of adigudom. depth (cm) ph sand (%) silt (%) clay (%) tn (%) oc (%) si (g kg-1 soils) 0-15 8.4 16 22 62 0.116 1.5 87.1 15-30 8.4 18 22 60 0.106 1.4 87.4 30-45 8.3 14 23 63 0.084 1.0 87.5 45-60 8.4 16 20 64 0.082 1.4 84.6 60-90 8.6 12 26 62 0.081 1.4 82.3 90-140 8.0 18 64 22 0.095 1.8 74.8 140-160 8.4 14 28 54 0.070 1.0 79.1 mekelle university issn: 2073-073x 77 fassil k. (mejs) volume 1 (1): 74 – 81, 2009 table 2. physical and chemical properties of vertisols of axum. depth (cm) ph sand (%) silt (%) clay (%) tn (%) oc (%) si (g kg-1 soils) 0-15 8.4 14 34 52 0.148 1.2 111.3 15-30 8.5 12 30 58 0.127 1.1 114.1 30-45 9.0 12 24 64 0.120 1.0 114.8 45-60 9.0 12 26 62 0.111 0.9 112.7 60-90 9.1 16 24 60 0.116 0.8 115.2 90-140 8.7 16 28 56 0.062 0.8 109.1 140-160 8.3 18 26 56 0.051 0.6 97.7 table 3. physical and chemical properties of vertisols of maychew. depth (cm) ph sand (%) silt (%) clay (%) tn (%) oc (%) si (g kg-1 soils) 0-15 7.4 20 20 60 0.106 0.7 113.7 15-30 7.8 20 32 60 0.069 0.6 113.8 30-45 8.0 20 32 48 0.067 0.5 114.7 45-60 8.1 18 30 48 0.041 0.3 114.5 60-90 8.4 14 30 52 0.040 0.3 114.8 90-140 6.4 14 30 56 0.038 0.3 117.2 table 4. physical and chemical properties of vertisols of shire. depth (cm) ph sand (%) silt (%) clay (%) tn (%) oc (%) si (g kg-1 soils) 0-15 6.9 10 32 58 0.057 0.7 133.1 15-45 7.0 10 32 58 0.069 0.6 133.9 45-60 7.3 12 28 60 0.073 0.6 130.9 60-90 7.5 12 28 60 0.050 0.5 131.9 90-140 7.5 12 28 60 0.043 0.7 130.0 mekelle university issn: 2073-073x 78 fassil k. (mejs) volume 1 (1): 74 – 81, 2009 table 5. physical and chemical properties of vertisols of wukro. depth (cm) ph sand (%) silt (%) clay (%) tn (%) oc (%) si (g kg-1 soils) 0-15 8.2 50 20 30 0.078 1.0 166.3 15-30 8.2 40 20 40 0.088 1.4 153.8 30-45 8.5 33 23 44 0.090 1.1 141.1 45-60 8.3 33 23 44 0.092 1.1 137.3 60-90 8.5 31 20 49 0.060 1.0 141.3 90-140 8.7 13 38 49 0.066 1.0 144.9 140-160 8.5 36 17 47 0.063 0.9 146.5 table 6. correlation between silicon and major soil physical and chemical properties in vertisols of tigray. soil properties adigudom axum maychew shire wukro ph 0.53 0.67 -0.67 -0.81 -0.56 sand -0.08 -0.73 -0.75 -0.88(*) 0.65 silt -0.85(*) -0.01 0.30 0.88(*) -0.22 clay 0.85(*) 0.45 -0.16 -0.88(*) -0.85(*) total n 0.39 0.77(*) -0.65 0.43 0.00 soil organic c -0.15 0.67 -0.73 0.70 -0.05 * correlation is significant at the 0.05 level (2-tailed). 4. discussion the si values in the vertisols of tigray are less than from the previously reported si content for clay soils. as silicon is the most abundant element in the earth’s crust after oxygen, it ranges from 200 to 300 g si kg-1 in clay soils and 450 to 480 g si kg-1 in sandy soils (kovda, 1973; matichenkov and calvert, 2002). although the si contents in vertisols of debre zeit and sheno in the central highlands of ethiopia fall within this range (fisseha itanna, 1992), the clay soils in tigray region have much lower si. the comparatively lower values for si in these soils can be justified due to; first, severe and frequent soil erosion and sediment transportation in the study areas. secondly, usually plants absorb si more than other elements (savant et al., 1997); hence, mekelle university issn: 2073-073x 79 fassil k. (mejs) volume 1 (1): 74 – 81, 2009 much si should be replaced to ensure sustainable yields. thirdly, the nature of parent materials in the study areas could be the cause for the lowered si levels in these soils. virtually, the main portions of soil si-rich compounds are represented by quartz or crystalline silicates, which are confirmed in this current studies where the highest si content was found in sand dominated soils. the physically and chemically active si substances in the soils are represented by soluble and weakly adsorbed monosilicic acids, polysilicic acids, and organosilicon compounds (matichenkov and ammosova, 1996). these forms are interchangeable with each other as well as with other crystalline minerals and living organisms (soil microorganisms and plants). monosilicic acid is the center of these interactions and transformations. monosilicic acids are the product of si-rich mineral dissolution (lindsay, 1979). plants and microorganisms can absorb only monosilicic acid (yoshida, 1975). polysilicic acid has a significant effect on soil texture, water holding capacity, adsorption capacity, and soil erosion stability (matichenkov et al., 1995). the study concludes that quantifying monosilicic and polysilicic acid contents and conduct applied research so as to elaborate optimum si rate and best time and methods of its application are imperative. it is also advisable to consider additional si extractants to those used in this study. plant uptake studies may also be useful to justify whether it contributes to the low levels of si in tigray region. 5. acknowledgement the researcher duly acknowledges the ethiopian institute of agricultural research for funding the project and technicians of the department of land resource management and environmental protection of mekelle university for sample collection. 6. references bremner, j.m. & mulvaney, c.s. 1982. total nitrogen. in: a.l. page, r.h. miller and d.r. keeney (eds.), methods of soil analysis, part 2 chemical and microbiological properties. agronomy, am. soc. of agron., madison, wisconsin, 9 (2): 595-624. epstein, e. 1999. the discovery of the essential elements. in: s.d. kung and s.f. yang (eds.), discoveries in plant biology, volume 3, world scientific publishing, singapore. fassil kebede. 2002. analysis of yield gap for wheat cultivation in the highlands of north ethiopia. ph.d thesis, gent university, belgium (unpubl.). mekelle university issn: 2073-073x 80 fassil k. (mejs) volume 1 (1): 74 – 81, 2009 fisseha itanna. 1992. microand macronutrient distributions in ethiopian vertisol landscapes. ph.d thesis, hohenheimer bodenkundliche hefte (2), university of hohenheim, stuttgart, germany (unpubl.). iler, r. k. 1979. the chemistry of silica – solubility, polymerization, colloid and surface properties, and biochemistry. wiley & sons, new york, pp. 866. jones, l.h.p. & handreck, k.a. 1967. silica in soils, plants and animals. adv. agron., 19: 107149. kovda, v.a. 1973. the bases of learning about soils. volume 2, nauka, moscow. lindsay, w.l.1979. chemical equilibria in soil. john wiley & sons, new york. marschner, h. 1996. mineral nutrition of higher plants. academic press inc san diego, ca 92101. matichenkov, v.v., pinsky, d.l. & bocharnikova, e.a. 1995. influence of mechanical compaction of soils on the state and form of available silicon. eurasian soil science, 27 (12):58-67. matichenkov, v.v. & ammosova. 1996. effect of amorphous silica on soil properties of a sodpodzolic soil. eurasian soil science, 28 (10):87-99. matichenkov, v.v. & bocharnikova, e.a. 2000. comparison study of soil silicon status in sandy soils of south florida. proc. soil crop sci., florida, 59:132-137. matichenkov, v.v. & calvert, d.v. 2002. silicon as beneficial element for sugarcane. j. american society of sugarcane technologists, volume 22. savant, n.k., korndorfer, g.h. & datnoff, l.e. 1997. silicon management and sustainable rice production. advances in agronomy, 58:151-199. takahashi & miyake, 1977. silica and plant growth. proc. int. seminar, soil environ. fert. management intensive agriculture, 603-611. walkley, a. & black, i.a. 1934. an examination of the degtijareff method for determining soil organic matter and proposed chromic and titration method. soil science, 37:29-38. yoshida, s. 1975. the physiology of silicon in rice. bulletin no.25, food fert. tech. centre, taipei, taiwan. mekelle university issn: 2073-073x 81 kbheema momona ethiopian journal of science (mejs), v6(2)95-109, 2014 ©cncs, mekelle university, issn:2220-184x agronomic performance of some haricot bean varieties (haseolus vulgaris l.) with and without phosphorus fertilizer under irrigated and rain fed conditions in the tigray and afar regional states, northern ethiopia gebre-egziabher murut, hadush tsehaye and fetien abay* department of dryland crop and horticultural sciences, mekelle university, p.o. box 231, mekelle, tigray, ethiopia (*fetienabay@gmail.com) abstract haricot bean is an important source of protein, calories and cash for small holder farmers of ethiopia. five genotypes of haricot bean were grown with and without phosphorous fertilizer application, under irrigation and rain fed growing conditions in randomized complete block design with three replications in three locations of the tigray and afar regional states, northern ethiopia. the aim of the study was to examine the performance and select the best and well adapted varieties, as well as to determine the role of phosphorus on yield response of varieties and on root nodulation. varieties like awash-1 and mexican-142 were better in terms of earliness to maturity. variety chore exhibits high mean grain yield (24.5 qt/ha under irrigation and 19.6 qt/ha under rainfed) followed by awash-melka (20.7qt/ha under irrigation and 19 qt/ha under rainfed). phosphorus application did not significantly affect various parameters examined and its effect was erratic and inconsistent. significant variations were observed among haricot bean varieties for number of nodules per plant. it is recommended to grow early maturing varieties awash-1 and mexican 142 under rain-fed and the intermediate to late maturing and better yielding varieties such as awash-melka and chore under irrigation. keywords: haricot bean varieties, fertilizer-p, growing season, northern ethiopia. 1. introduction haricot bean (phaseolus vulagris l), locally known as ‘boleqe’ also known as dry bean, common bean, kidney bean and field bean is a very important legume crop grown worldwide. it is an annual crop which belongs to the family fabaceae. it grows best in warm climate at temperature of 18 to 24 o c (teshale et al., 2005). despite the importance for nutrition and export, its cultivation in tigray and afar areas is limited to small areas. potential haricot bean varieties which were released from ethiopian agricultural research centers should be tested in those areas in order to expand its area of production and increased productivity. haricot bean is primarily a crop of small scale producers and generally few inputs are used or no fertilizer or no soil amendments (wortman et al., 1995). the crop is adapted to a wide range of climatic condition ranging from sea level to nearly 3000 meters above sea level (m.a.s.l.) depending on variety selection. however, it does not grow well below 600 meters due to poor pod set caused by high temperature (dev and gupto, 1997). gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 96 in ethiopia, haricot bean is grown predominantly under smallholder producers as an important food crop and source of cash. it is one of the fast expanding legume crops that provide an essential part of the daily diet and foreign earnings for most ethiopians (girma, 2009). the major haricot bean producing areas of ethiopia are central, eastern and southern parts of the country (csa, 2011). the crop grows well between 1400 and 2000m above sea level (fikru, 2007). in 2011/12, total haricot bean production in the country was about 3,878,023.01 quintals (1.77% of the grain production) on approximately 331,708.15 hectares of land (2.74% of the grain crop area) (csa, 2011). the wide range of growth habits of haricot bean among varieties has enabled the crop to fit many growing situations (kristin et al., 1997). early maturity and moderate degree of drought tolerance led the crop’s vital role in farmers’ strategies for risk aversion in drought prone lowland areas of the country (fikru, 2007). however, yield per unit area is very low especially in tigray, northern ethiopia which is about 8.24 qt/ha, compared to the national average of 11.67 qt/ha (csa, 2011). this low yield is attributed to various constraints such as moisture stress, absence of improved high yielding varieties, low soil fertility, losses due to insect pests and disease (eden, 2002; ferris and kaganzi, 2008; girma, 2009). varieties differ for their response to these constraints but are largely influenced by the environmental conditions (wortman et al., 1995). selection of varieties well adapted to the local agro-ecological conditions, soil fertility and moisture level could improve the productivity of haricot bean in these areas. however, little research is done so far in this regard, despite its importance the crop has been introduced inadequately to this part of the country. moreover, seeking for appropriate alternative n-fixing crops like haricot bean is essential to improve the soil fertility as well as increase crop production and livelihoods of farmers. bean productivity is greatly influenced by soil fertility especially phosphorous and nitrogen. they have high nitrogen requirement for expressing their generic potential and phosphorus plays an important role in biological nitrogen fixation (jakobson, 1985; hamdi, 1999). phosphorus appears essential for both nodulation and n2 fixation (ssali and keya, 1983). it is also the basis for the formation of useful energy, which is essential for sugar formation and translocation. nitrogen fixation in beans needs more inorganic phosphorus and phosphorus availability in soil is considered to be the major constraint to common bean production (israel, 1987). most soils of northern ethiopia particularly the study areas are depleted of nutrients because of the long years repeated cultivation and poor soil fertility management practices. farmers in the study areas gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 97 cultivate cereal crops continuously year after year; moreover, crop residues and cow dung are used for fuel instead of for soil conditioning. therefore, the aim of this study was to select the best performing and suitable variety/varieties of haricot bean for irrigated and rain-fed agriculture condition of the study areas. furthermore it was aiming to evaluate the role of phosphorous on yield performance and on root nodulation of some haricot bean varieties. 2. materials and methods 2.1. description of the study areas field experiment was conducted in three agro-ecological zones of two regions in northern ethiopia, the tigray and afar regional states namely in atsbi-wonberta (haikmeshal) and wukro (dongolo) (both from the tigray region) and at aba’ala (afar region) during the 2008 off season (using irrigation) and main season (under rain fed) growing conditions. all the testing sites are lowland to mid-altitude areas which have the potential for haricot bean production. they have also better water resources for irrigable crop production. atsbi (also known as atsbi endaselase) is located in the eastern zone of the tigray region. haikimeshal is one of the villages of this zone that located about 12 km south east of atsbi. the sites are located at a latitude and longitude of 13°52′n and 39°44′e, and 13.867°n and 39.733°e respectively with an elevation of 2630 meters above sea level (m.a.s.l). its mean annual rain fall is 260.25 mm (board 2011). aba’ala (also known as shiket) is a town in afar regional state, situated at a latitude and longitude of 13°22′n and 39°45′e with an elevation of 1482 m.a.s.l. its mean annual rain fall is 260.25 mm (board, 2011). dengelo is a village near the vicinity of the wukro town located in the area stretching from 13°33'-13°58' north latitude and 39°18'-39°41' east longitude with elevation ranging from 1760 to 2720 m.a.s.l. the annual average rainfall of the area ranges from 350-450mm. the annual average rainfall of the area ranges from 350-450mm. 2.2. experimental design and layout five haricot bean varieties (awash-1, awash-melka, argen, mexical-142 and chore) and two p-fertilizer levels (0 and 46 kg p2o5 /ha) in a factorial combination were used as a treatments (combined in to ten treatments). the experiment was laid out in a randomized complete block design (rcbd) with three replications. all the test varieties were white seeded obtained from the melkasa agricultural research center (nazareth). the p-level applied to plots was calculated http://en.wikipedia.org/wiki/misraqawi_zone http://en.wikipedia.org/wiki/tigray_region http://tools.wmflabs.org/geohack/geohack.php?pagename=atsbi&params=13_52_n_39_44_e_ http://tools.wmflabs.org/geohack/geohack.php?pagename=abala%2c_abala%2c_ethiopia&params=13_22_n_39_45_e_ gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 98 from the rate recommended for pulse crops, which is 100 kg/ha dap. the source of fertilizer was tsp (46% p2o5 or 20% p) and it was applied during planting as a top dressing. the size of the experimental plots was 3 m x 4.2m (12.6m 2 ) with 1.5 m spacing between blocks and 1.0 m between plots. each plot had 7 rows. the inter-row and intra-row spacing were respectively 0.6 m and 0.2 m. the central five rows were used for data collection. all agronomic practices such as land preparation and weeding were performed as per the local farmers’ practices. 2.3. sampling and preparation of soil for laboratory analysis for site characterization, composite (0-30cm) top soil sample were taken using a soil auger from the all the trial sites and subjected to physical and chemical analysis before planting and after harvesting. the soil samples were air dried and ground to pass through 0.2 mm sieve and analyzed for total n, available p, ph, organic carbon (oc), available k, ec, and physical properties at mekelle university soil laboratory. soil analysis was made as per the normal laboratory procedure. available phosphorus in soil was estimated by olsen extraction method (olsen et al., 1954). the content of p extracted by olsen method was determined using spectrophotometer following the procedure described by murphy and reliy (1968). the chemical and physical properties of the soil before planting are presented in table 1. 2.4. data collection and statistical analysis data on agronomic traits such as days to physiological maturity, number of pods per plant, number of seeds per pod, 1000 seed weight and grain yield were recorded. number of root nodules per plant was also recorded at 30, 45 and 65 days after crop emergence (dae). data for pod/plant and number of root nodules/plant were collected from the average value of randomly selected five plants/plot. analysis of variance was performed using genstat and mstat-c software. duncan multiple range test was computed at 5% to delineate significance difference between treatments, varieties and locations. bartlet’s test was applied for homogeneity of variance test (steel and torrie, 1998). correlation coefficients were computed to assess the relationships between yield and yield components of the common bean varieties across locations. 3. results 3.1. chemical and physical properties of soils of the experimental sites before planting and after crop harvest the available phosphorus of the experimental sites was higher after harvesting than before gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 99 planting (tables 1 & 2). comparing to landon and booker (1991) standards, haikimeshal and wukro sites were p-deficient whereas shiket had adequate phosphorus before and after planting. similarly, all the experimental sites were deficient in nitrogen before and after planting (tables 1 & 2). similarly, experimental sites vary in their organic carbon. shiket has highest organic carbon. the ph levels of all the experimental sites were slightly higher and relatively skewed towards the alkaline state. table 1. chemical and physical properties of soil (0-30 cm) of experimental sites before planting. s.no. nutrient content and textural class experimental sites (testing locations) haikmeshal shiket wukro 1 organic carbon (%) 0.663 3.63 0.74 2 ec (ds/m) 0.08 0.58 0.21 3 available p in ppm (mg/kg soil) 5.06 14.04 5.52 4 available k in ppm (mg/kg soil) 78.53 450.76 73.36 5 total nitrogen (%) 0.03 0.16 0.03 6 ph (paste) 7.96 8.07 8.29 7 sand (%) 54 22.36 40 8 silt (%) 27.64 61.28 41.64 9 clay (%) 18.36 16.36 18.36 10 textural classification sandy silt loam loam table 2. chemical and physical properties of soil of experimental sites sampled after crop harvest. s.no. soil characteristics analytical & textural results for the untreated plots analytical & textural results for the treated plots h/meshal shiket wukro h/meshal shiket wukro 1 soil ph (paste) 8.44 8.11 8.56 8.36 7.99 8.48 2 organic carbon (%) 1.056 2.21 0.95 1.074 0.95 0.91 3 total nitrogen (%) 0.076 0.17 0.084 0.0812 0.084 0.0812 4 e.c (ds/m) 0.13 1.13 0.21 0.08 1.23 0.21 5 available p in ppm (mg/kg soil) 2.16 12.26 2.66 4.28 26.5 4.6 6 sand (%) 56.36 24.36 42.36 54.36 24.36 44.36 7 silt (%) 29.28 41.28 39.28 29.28 40.38 39.28 8 clay (%) 14.36 34.36 18.36 16.36 35.36 16.36 9 textural classification silt loam clay loam loam silt loam clay loam loam 3.2. agronomic performance of haricot bean varieties 3.2.1. days to physiological maturity highly significant variations were observed (p<0.001) among haricot bean varieties for days to gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 100 maturity both under irrigation and rainfed growing conditions. varieties like awash-1 and mexican-142 were more early (90-94 days) than others whereas the variety chore requires relatively more days (100-114 days) to reach maturity (table 4). there was also significant variation among localities in influencing the days required to reach physiological maturity (table 3). most varieties required relatively shorter days to reach maturity at shiket (87days) than the other localities. however, application of p-fertilizer did not affect maturity of the haricot bean varieties (table 3). relatively less number of days was required to reach maturity under irrigation than under rain-fed growing condition table 3. response of haricot bean varieties with and without p-fertilizer for days to maturity under irrigated and rain-fed conditions. days to physiological maturity testing locations mean of combined analysis source haikimeshal wukro shiket rf ir ir rf ir rf ir rf awash 1 94.5 c 88.0 b 97.3 cd 94.2 b 86.00 c na 94.4 c 94.33 c awash melka 1o6.2 b 98.0 a 102.0 b 110.8a 99.17b na 96.39b 108.5 b argen 104.5 b 92.2 b 98.0 c 107.3a 106.50a na 92.22c 105.9 b mexican-142 96.3 c 88.0 b 94.0 d 92.5b 86.67c na 89.56c 94.42 c chore 113.7 a 101 a 106.0 a 114.3 a 113.50 a na 100.3 a 114.0 a significance level ** * ** ** ** ** ** se± 1.83 0.9 2.24 2.79 0.9 na 0.914 1.66 cv (%) 4.34 4.1 3.1 6.6 4.1 na 4.1 5.59 p1 = 46 kg p2o5/ha 103.5 a 95 a 100.6 a 103.5 a 88.67a na 94.76 a 103.9 a p0 = 0 kg p2/ha 102.5 a 94 a 99.4 a 104.2 a 85.67 a na 93.02 b 103 a significance level ns ns ns ns ns -* ns se± 1.15 0.57 3.16 1.77 0.57 na 0.914 1.05 c.v% 4.34 4.1 3.1 6.6 4.1 na 4.1 5.59 key: treatments followed by similar letters are not statistically significant , * p<0.05, ** p<0.01, ns = non-significant, rf= rain fall, ir=irrigation, na= data not recorded due to early season drought crop failure. 3.2.2. number of pods per plant significant differences (p<0.001) were exhibited among haricot bean varieties for number of pods per plant. relatively more numbers of pods/plant were recorded from chore variety with a respective 30 and 13.79 pods per plant under irrigation and rainfed growing condition. on the gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 101 other hand, awash-melka had the lowest number of pods per plant with a respective pod number/plant of 25.4 and 10 pods under irrigation and rainfed growing conditions respectively (table 4). application of p-fertilizer did not affect the number of pods per plant. generally, more number of pods per plant was recorded from the irrigated trial (25.4-29.98 pods per plant) than the rain fed growing condition (10.05-13.79 pods per plant). table 4. response of haricot bean varieties with and without p-fertilizer for number of pods per plant under irrigated and rain-fed conditions. number of pods per plant source testing locations mean of combined analysis haikimeshal wukro shiket ir rf ir rf ir rf ir rf awash 1 17.6 b 11.3b 9.6 bc 9.1b 57.90 a -na 28.337 b 10.17 b awash-melka 14.8 b 11.2b 9.2 c 8.9 b 52.20 a 25.388 c 10.05 b argen 22.3 a 14.2a 16 a 11.5 a 47.50 a 28.61b 12.83 a mexican-142 20.6 ab 11.9b 13.7 ab 9.5 b 60.20 a 31.489 a 10.73b chore 22.2 a 14.8a 12 abc 12.8 a 55.47 a 29.977 a 13.79 a significance level * ** ** ** ns * ** se± 2.5 0.47 4.7 0.33 4.7 2.5 0.28 cv (%) 38.2 9.22 3.71 7.73 17.81 27.8 8.7 p1 = 46 kg p2o5/ha 21.3a 13.1a 33.8a 10.5a 63.5a 38.4a 11.78 a p0 = 0 kg p2o5/ha 17.8a 12.3a 32.0a 10.2a 61a 38.1a 11.24 b significance level ns ns ns ns ns ns * se± 1.58 0.3 0.35 0.21 3.35 1.58 0.18 c.v% 38.2 9.22 3.71 7.73 17.81 27.8 7.8 key: treatments followed by similar letters are not statistically significant, * p<0.05, ** p<0.01, ns = non-significant, rf= rain fall, ir= irrigation, na= data not recorded due to early season drought crop failure 3.2.3. average number of seeds per pod haricot bean varieties were exhibited variation for number of seeds per pod. the variety awash-melka produces more number of seeds per pod (6.46 under irrigation and 7.43 under rain fed growing condition) compared to the other varieties. on the other hand, mexican-142 produces the lowest number of seeds per pod about 5.69 and 5.33 seeds per pod under irrigation and rain fed condition, respectively (table 5). as shown in the table application of p-fertilized did not show any influence on number of seeds per pod (among locations and season (irrigation and rain fed growing condition). gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 102 table 5. response of haricot bean varieties with and without p-fertilizer for number of seeds/ pod under irrigated and rain fed conditions. number of seeds per pod source testing locations mean of combined analysis haikimeshal wukro shiket ir rf ir rf ir rf ir rf awash 1 6.2a 6.1b 5.43a 5.4b 6.856ab -na 6.17a 5.77b awash-melka 6.6a 7.3a 5.73a 7.6a 7.068a 6.46a 7.43a argen 5.9a 6.5b 5.37a 5.7b 5.975c 5.77b 6.00b mexican-142 5.9a 5.4c 5.67a 5.3b 5.638c 5.69b 5.33b chore 6.3a 6.4b 6.20a 6.1b 6.575b 6.36a 6.28b significance level ns ** ns ** ** ** ** se± 0.157 0.21 0.157 0.32 0.087 0.097 0.19 cv (%) 6.3 8.17 6.8 13.34 6.8 6.8 10.93 p1 = 46 kg p2o5/ha 6.3a 6.35a 5.77a 5.9a 5.77a 6.14a 6.13 a p0 = 0 kg p2o5/ha 6.1a 6.34a 5.54a 6.1a 5.54a 6.05a 6.24 a significance level ns ns ns ns ns ns ns se± 0.088 0.13 0.087 0.21 0.087 0.06 0.12 c.v% 6.3 8.17 8.91 13.34 5.61 6.8 10.93 key: treatments followed by similar letters are not statistically significant (p<0.05), * p<0.05, ** p<0.01, ns = non-significant, rf= rain fall, ir= irrigation, na= data not recorded due to early season drought crop failure. table 6. response of haricot bean varieties with and without p-fertilizer for grain yield under irrigated and rain fed conditions. grain yield (qt/ha) source testing locations mean of combined analysis haikimeshal wukro shiket rf ir ir rf ir rf ir rf awash-1 16.44c 19.8b 14.8a 16.1ab 31.1a na 23.0 a 16.5b awash-melka 19.87a 18.81b 11.6a 18.3a 28.3a 20.7 ab 19.0a argen 18.33b 20.14b 18.0a 15.6b 20.3b 15.6 c 17.0b mexican-142 17.40bc 21.80b 17.9a 15.5b 22.5b 20.5 ab 16.5b chore 20.78a 30.10a 15.3a 18.5ab 27.0a 24.5 a 19.6a significance level ** * ns * ns * ** se± 0.05 0.087 0.087 0.7 0.087 0.087 0.42 cv (%) 4.45 32.9 32.9 7.98 31.98 32.9 6.6 p1 = 46 kg p2o5/ha 19.71a 22.9 15.3a 18.1 22.8a 21.9 a 18.5a p0 = 0 kg p2o5/ha 17.22b 21.30 15.2a 15.1 17.5b 21.6 a 16.0b significance level ** ns ns ** * ns ** se± 0.3 0.055 0.055 0.44 0.055 0.055 0.27 key: treatments followed by similar letters are not statistically significant (p<0.05), * p<0.05, ** p<0.01, ns = non-significant, rf= rain ; the haricot bean varieties tested had a fall, ir= irrigation, na= data not recorded due to early season drought crop failure. gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 103 3.2.4. grain yield a significant variation was observed among haricot bean varieties in their response to gain yield. the highest yield was recorded from the variety chore under irrigation growing condition (24.5 qt/ha) while awash-melka was the highest yielder under rain fed growing condition (19 qt/ha). the application of p-fertilizer had positive effect on yield because fertilized plots gave better yield compared to unfertilized plots in the rainfed growing condition (table 6). grain yield was generally higher under irrigation compared to rainfed growing condition. 3.2.5. thousand seed weight the haricot bean varieties tested had a significant variation among each other for thousand seed weight. under irrigated growing condition, the variety awash-melka produces the highest seed weight (295.79 gm) while under rain-fed growing condition the variety chore was the highest (298.8 gm) followed by awash-melka (287.8 gm). the variety argen was the least in seed weight. there was no positive influence of p-fertilizer application on seed weight of the haricot bean varieties (table 7). table 7. response of haricot bean varieties with and without p-fertilizer for thousand seed weight under irrigated and rain fed conditions. 1000 seed weight (gm) source testing locations mean of combined analysis haikimeshal wukro shiket rf ir ir rf ir rf ir rf awash 1 281.5bc 294.5b 276.5b 267.2c 252.73a -na 274.56b 274.3c awash melka 284.5b 313.6a 314.9a 291.0ab 258.72a 295.79a 287.8b argen 274.0c 259.5d 276.4b 259.3c 250.55a 262.15c 266.7d mexican-142 283.3b 273.8cd 271.1b 284.7b 251.52a 265.46cb 284.0b chore 297.2a 278.3c 275.9b 300.5a 243.70a 265.98cb 298.8a significance level ** ** * ** ns ** ** se± 2.56 3.2 3.2 4.5 3.2 3.2 2.6 cv (%) 2.69 7.9 7.9 4.84 8.48 7.9 3.9 p1 = 46 kg p2o5/ha 286.9 a 286.4a 283.6a 282.2a 254.6a 274.9a 284.6a p0 = 0 kg p2o5/ha 281.2 b 282.0a 283.8a 278.8a 248.5a 271.4a 280.1a significance level * ns ns ns ns ns ns se± 1.63 2.04 2.04 2.87 2.04 2.04 1.7 c.v% 2.69 7.9 7.9 4.84 8.48 7.9 3.9 key: treatments followed by similar letters are not statistically significant (p<0.05), * p<0.05, ** p<0.01, ns = non-significant rf= rain fall, ir= irrigation, na= data not recorded due to early season drought crop failure. gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 104 table 8. response of haricot bean varieties with and without p-fertilizer for nodulation at 30 days after emergence under irrigated and rain fed conditions. number of nodules/plant at 30 dae source testing locations mean of combined analysis haikimeshal wukro shiket ir rf ir rf ir rf ir rf awash 1 0.524a 0.17c 0.00a 0.000b 0.00 na 0.175a 0.0883 b awash melka 0.539a 1.19ab 0.24a 1.228 a 0.00 0.258a 1.209 a argen 0.524a 0.00c 0.28a 0.523b 0.00 0.271a 0.262 b mexican-142 0.000a 0.50bc 0.00a 0.000b 0.00 0.00a 0.250 b chore 1.069a 1.33a 0.47a 1.335a 0.00 0.513a 1.335 a significance level ns ** ns ** ns ns ** se± 0.14 0.25 0.14 0.21 0.14 0.14 0.168 cv (%) 61 46 33.7 27.3 9.4 61.1 27.6 p1 = 46 kg p2o5/ha 0.586a 0.57a 0.304a 0.701a 0.00a 0.297a 0.635a p0 = 0 kg p2o5/ha 0.476a 0.71a 0.094a 0.534a 0.00a 0.190a 0.620a significance level ns ns ns ns ns ns ns se± 0.089 0.163 0.089 0.13 0.089 0.089 0.106 c.v% 61 46 33.7 27.3 9.4 61.1 27.6 key: treatments followed by similar letters are not statistically significant (p<0.05), * p<0.05, ** p<0.01, ns = non-significant rf= rain fall, ir= irrigation, na= data not recorded dueto early season drought crop failure. table 9. response of haricot bean varieties with and without p-fertilizer for nodulation at 45 days after emergence under irrigated and rain fed. number of nodules/plant at 45 dae source testing locations mean of combined analysis haikimeshal wukro shiket rf ir ir rf ir rf rf ir awash 1 2.67 b 7.50a 1.833a 2.517c 1.00a -na 4.5 c 3.44ab awash melka 10.17 a 11.00a 6.50a 3.197a 0.83a 10.25a 6.11ab argen 2.50 b 5.67a 3.50a 2.813b 1.17a 5.25bc 3.44ab mexican-142 7.17 a 1.17a 1.33a 2.413c 0.33a 6.50b 0.94c chore 10.67 a 24.67a 5.00a 3.282a 1.50a 10.75a 10.39a significance level ** ns ns ** ns ** * se± 0.302 0.335 0.335 0.073 0.2 0.61 0.9 cv (%) 31.5 15.2 26.9 13.59 99.61 28.1 99.6 p1 = 46 kg p2o5/ha 6.73a 10.0a 3.70a 2.77a 1.72a 7.68 a 4.90a p0 = 0 kg p2o5/ha 6.53a 9.41a 3.65a 2.17b 1.45a 7.21 a 4.86a significance level ns ns ns * ns ns ns se± 0.19 0.21 0.2 0.046 0.2 0.38 0.3 c.v% 31.5 15.2 26.9 13.59 99.6 28.1 99.6 key: treatments followed by similar letters are not statistically significant (p<0.05),* p<0.05, **p<0.01, ns = non-significant rf= rain fall, ir= irrigation, na= data not recorded due to early season drought crop failure. gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 105 3.2.6. number of root nodules per plant the tested varieties exhibited a significant variation for root nodulation. the variety chore had the highest root nodule per plant followed by awash-melka both under irrigation and rain-fed growing condition. nodule number per plant was more in the late sampling dates (45 and 65 dae) than the early sampling dates (30 dae) (tables 8, 9 and 10). nevertheless, application of p-fertilizer did not influence the number of nodules per plant. there was also significant variation among locations in terms of nodule number per plant. the least number of nodules was recorded from shiket whereas more number of nodules per plant was recorded at haikimeshal under irrigation and at wukro under rain-fed growing condition. more number of root nodules was recorded under the rain-fed growing condition compared to irrigated growing condition. table 10. response of haricot bean varieties with and without p-fertilizer for nodulation at 60 days after emergence under irrigated and rain fed conditions. number of nodules/plant at 60 dae source testing locations mean of combined analysis haikimeshal wukro shiket rf ir ir rf ir rf rf ir awash 1 9.00 b 1.67a 1.3a 11.2bc 1.33ab -na 10.08b 1.44 b awash melka 16.83 a 5.17a 4.5a 16.7a 0.83b 16.75a 3.5 a argen 6.50 b 3.50a 1.3a 12.5b 1.00b 9.5b 1.94 b mexican-142 9.67 b 1.17a 1.0a 10.3c 0.67b 10.00b 0.95 b chore 17.50 a 10.8a 3.8a 17.0a 2.17a 17.25a 5.61a significance level ** ns ns ** * ** ** se± 0.295 0.256 0.296 0.48 0.25 0.89 0.256 cv (%) 22.0 195.36 96 8.73 60.5 24.37 31.6 p1 = 46 kg p2o5/ha 10.87a 4.50a 2.46a 14.3a 1.30a 12.83 a 1.35a p0 = 0 kg p2o5/ha 12.93a 4.46a 2.20a 12.7b 0.89a 12.60 a 1.05a significance level ns ns ns ** ns ns ns se± 0.187 0.16 0.16 0.31 0.16 0.56 0.16 c.v% 22.0 195.36 96 8.73 60.5 24.37 31.6 key: treatments followed by similar letters are not statistically significant (p<0.05), * p<0.05, ** p<0.01, ns = non-significant rf= rain fall, ir= irrigation, na= data not recorded due to early season drought crop failure. 3.3. correlation analysis correlation coefficients were computed to assess the relationships between yield and yield gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 106 components of the common bean varieties across locations. plant height had highest positive correlation with number of pods per plant at wukro and shiket, grain yield and biomass yield at wukro and, number of pods per plant at shiket (see tables 1-2). plant height had a negative correlation with number of pods per plant, days to flowering, average pod length and days to green maturity at haikimeshal, days to flowering at shiket and days to green maturity, thousand seed weight and nodulation at wukro site. the plant height had also less association with number of branches at both haikimeshal and wukro. number of pods per plant had highest positive correlation with grain yield at shiket, showed less association with days to green maturity, average number of seeds per plant and thousand seed weight. biomass yield had highest positive correlation with grain yield, at all sites. in addition to this highest positive correlation for thousand seed weight was observed at the shiket site. this trait had less association with nodulation at shiket experimental site (stables 1-3).grain yield had highest positive correlation with thousand seed weight at shiket site. this trait has showed less positive association with nodulation at haikimeshal. while highest negative correlation with nodulation was observed at wukro experimental site (see tables 1-3). 4. discussion genotypes mexican-142 and awash-1 were early maturing, whereas chore was late maturing. mexican-142 and awash-1 can grow well under rain-fed growing condition since these varieties required less number of days to reach maturity. considering the irrigated growing condition, shiket, haik-mesahil and wukro have the highest to the lowest potential environments for the production of haricot bean. the occurrence of severe early season drought at shiket drastically affects the crop survival and up in crop failure in this site. some haricot bean varieties perform well and give better yield compared to others. chore and awash-melka had significantly higher yield than the other varieties. the greatest yield of these varieties could be due to their inherent genetic potential. it could be also due to better local adaptation to the northern ethiopia environments. the variety argen generally performs poorly under both rainfed and irrigated growing condition. the trial sites are characterized with less moisture and low soil fertility condition, hence varieties which tolerate these stresses perform best. successful cultivars must have good yield and other essential agronomic characters. besides, their performance should be reliable over a wide range of environmental conditions. the basic cause of differences in stability gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 107 between genotypes is a wide occurrence of genotype x environment interactions (g x e). g x e is a differential genotypic expression across environments (abay and bjornstad, 2009). the genotype and the interaction sources affect genotype rankings within each environment and hence relevant for identifying mega environments and targeting genotypes. in such condition identifying single highly stable genotype associated with high yield across all environments is difficult. soil moisture and nutrition are important factors for the varieties to fully express their genetic potential; therefore, chore and awash-melka varieties could be the best choice for localities with better moisture condition or for irrigated growing condition whereas mexican-142 and awash-1 fits better for rain-fed growing conditions. the results showed that phosphorus application did not significantly affect various parameters examined and its effect was sometimes erratic and inconsistent. the only parameter significantly (p=0.05) influenced by application of fertilizer-p was grain yield. the erratic and inconsistent response to fertilizer-p could be due to transformation into in soluble forms. the added phosphorus might be rendered unavailable to plants in alkaline soils due to transformation into in soluble forms (saad et al., 2009). the most favorable ph of the soil where p is highly available to plants is in the range 5.5-7.0 (saad et al., 2009) which is not the case in soil of the experimental area (tables 1 and 2). haricot bean varieties showed great variation in their potential to produce root nodules per plant. chore and awash-melka had by far more number of nodules per plant than others. these varieties are characterized by having stronger stem and better plant vigor compared to the other varieties tested. these characteristics seem contributed to have more number of nodules per plant. more nodules per plant were recorded late in the season. this might be due to increase in soil moisture level. for legumes, nodulation and n2-fixation are dependent up on an adequate supply of both macro and micro nutrients. poor nodulation and poor plant vigour have been observed in beans grown in soils low in p content (kristin et al., 1997). fertilizer p increases bean yields and causes optimum nodulation earlier during bean growth (ssali and keya, 1983). the overall performance of the test varieties was good in all locations except shiket under rain fed growing condition. therefore, it is advisable to promote haricot bean as a rotation crop in the study areas to improve the fertility level of the soil, increase source of cash for farmers and foreign currency for the country as export crop. gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 108 5. acknowledgments the authors would like to acknowledge to norad-ii project of mu for covering the financial expenses in conducting this study. we would like also to appreciate the invaluable assistance of mekelle agricultural research center, atsibi-wonberta office of agriculture and rural development, and wukro police station for provide us experimental land. we are grateful for melkassa agricultural research center for providing us haricot bean seeds. lastly but not the least we would like to acknowledge all individuals who directly or indirectly contribute to the successful completion of the study. 6. reference abay f & bjørnstad a. 2009.specific adaptation of barley varieties in different locations in ethiopia. euphytica 167(2): 181–195. board 2011 metreological annual report of tigray region, unpublished central statistics authority (csa). 2011. agricultural sample survey 2010/11. report on area and production of crops (privat3 peasant holdings, “meher” season), vol. iv statistical bulletin 446, addis ababa: may, 2011. 1-82 dev, j & gupta, v.p. 1997. common bean historic view and breeding strategy. annals of biology, 13: 213 219. eden, t. 2002. uptake and response of haricot bean (phaseolus vulgaries l.) varieties to different levels of phosphorus application on entisol of alemaya. a thesis submitted to the school of graduate studies, alemaya university, 89p. ferris, s & kaganzi, e. 2008. evaluating marketing opportunities for haricot beans in ethiopia. fikru, mekonnen. 2007. haricot ban (phaseolus vulgaris l.) variety development in the lowland areas of wollo. proceedings of the 2 nd annual regional conference on completed crops research activities 18 21 september 2007, bahir dar, ethiopia, pp 86-93. girma abebe. 2009. effect of np fertilizer and moisture conservation on the yield and yield components of haricot bean (phaseolus vulgaris l.) in the semi-arid zones of the central rift valley in ethiopia. advances in environmental biology, 3: 302-307. hamdi, h. z. 1999. rhizobium-legume symbiosis and nitrogen fixation under severe conditions and in an arid climate. microbiology and molecular biology reviews.v 63(4):968–989 israel, d.w. 1987. investigation of the role of phosphorus in symbiotic nitrogen fixation. plant gebre-egziabher, m., hadush, t and fetien, a (mejs) volume 6(2):95-109, 2014 © cncs, mekelle university issn: 2220-184x 109 physiology, 84: 825-840. jakobson, i. 1985. the role of phosphorus in nitrogen fixation by young pea plants. physiol. plant, 64:190–196. kristin, a., schneider, r., rosales, s., francisco, i., benito, c., jorge, a., acosta-gallegos, porfirio., r, nasrat, w & james, d.k. 1997. improving common bean performance under drought stress. crop sci., 37: 43-50. landon and booker (1991) tropical soil survey and agricultural land evaluation in the tropics and subtropics. john wiley and sons. murphy and reliy (1968). a report on some soils of ethiopia. expert sta. bull no. 44. college of agriculture alemaya. pp 44. saad, a.s., muna, a.a., el tahir, a.o & tageldin, e.m.h. 2009. phosphorus supply and phaseolus vulgaris performance grown in shambat clayalkaline soil and influenced by farmyard manure. australian journal of basic and applied sciences, 3: 2598-2606. ssali, h & keya, s.o. 1983. the effect of phosphorus on nodulation, growth and dinitrogen fixation by beans. biol. agric. hortic., 1:135–144. steel, r.g & torrie, j.h. 1998. principles and procedures of statistic. 2nd edition, mcgraw-hill book co, new york, 633p. teshale, assefa, girma, abebe, chemeda, fininsa, bulti, tesso & abdel-rahman m. al-tawaha. 2005. participatory bean breeding with women and small holder farmers in eastern ethiopia. world journal of agricultural sciences, 1: 28-35. wortmann, c.s., lunze, l., ochwoh, v.a & lynch, j. 1995. bean improvement for low fertility soils in africa. african crop science journal, 3: 469 – 477. momona ethiopian journal of science (mejs), v5(1):32-50, 2013, ©cncs, mekelle university, issn:2220-184x petrography and geochemistry of ferricrete near shire, northern ethiopia bheemalingeswara konka * , solomon gebreselassie and ebrahim nesro hussen department of earth sciences, cncs, p.o.box. 3066, mekelle university, mekelle, ethiopia (*kbheema@hotmail.com) abstract a detailed petrographic and geochemical study was conducted on ferricrete (laterite) developed on mesozoic (?) ferruginous sandstone near shire, tigray region, northern ethiopia. 30 rock samples were analyzed for major and minor elements and studied for petrographic details. ferruginous sandstone overlying the neoproterozoic low grade basement rocks dominantly contains quartz followed by orthoclase feldspar and iron oxides/hydroxides as cement. residual enrichment process has resulted in the development 2-3m thick ferricrete horizon and also subhorizons: mottled, mixed nodular and psuedo-pisolitic. mineralogy of the ferricrete includes limonite, goethite and hematite. arid conditions and dehydration reactions seem to have produced hematite from goethite. the ore minerals show replacement, cavity and fracture filling, remobilization and colloform textures. si>al>fe is the mobility pattern observed in the ferricrete horizon though presence of secondary quartz and kaolinite are also common. development of ferricrete is related to the climatic condition that existed during eocene and is comparable with similar deposits in arabian nubian shield (ans). key words: ferricrete, laterite, ferruginous sandstone, shire, tigray, northern ethiopia, ans. 1. introduction in ethiopia, minable iron deposits reported so far are very few. three different types of deposits are reported from ethiopia, though small in size. they include magmatic iron (fe-ti type) of precambrian age from bikilal, melka arba areas, banded iron formation (bif type) of precambrian age from koree, gordoma, chago areas, and lateritic (also gossan related) iron deposits (residual type) from melka sedi, garo, gato, billa, gambo, and gammalucho areas. among them, garo, dombova and melka sedi (in kaffa) are the biggest about 12.5 mt each in terms of reserve. metals associated with iron in these deposits are mainly mn, au, pt, ni, co etc (tadesse, 2006). bikilal deposit is dominated by apatite and followed by magnetite and ilmenite etc. the mineable reserve of apatite in the deposit is about 181 mt with a grade of 3.5% (p2o5)and iron ore of 58 mt with a grade of 41.65% total iron (wondafrash, 2010; tadesse, 2006).occurrence of laterite (ferricrete) deposits are also reported in tigray region, northern ethiopia e.g.1) occurrence of pockets of lateritic deposits near shire (ebrahim, 2011) overlying ferruginous sandstone; 2) development of thin lateritic cover on enticho sandstone of paleozoic age near wukro and sinkata; 3) negash iron deposit near wukro as cavity filling in neoproterozic metalimestone by the younger remobilized lateritic material possibly bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 33 issn:2220-184x related to iron-rich paleozoic enticho sandstone (gebresilassie et al., 2012);and 4) presence of iron–rich bands within adigrat sandstone of mesozoic age near wukro, hawzein, dugum, adigrat etc. at present among the reported iron deposits of lateritic type are the major resources in terms of tonnage (>100mt) and hence are attracting attention of companies like ezana mining company plc (emd) and universities like mekelle university to conduct research. present paper is the result of one such effort on ferricrete near shire, northern ethiopia. figure 1. map of part of ethiopia and east africa showing some of the iron occurrences including the shire area (after mengesha et al.,1996). bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 34 issn:2220-184x 2. geological setting 2.1. regional geologic setting northern ethiopia forms part of southern arabian-nubian shield (ans) and consist of precambrian low-grade volcanic, volcano-sedimentary, mafic and ultramafic rocks of ophiolitic character and are intruded by synand post-tectonic plutonic rocks (tadesse, 1997). the rocks have experienced different phases of deformation. the tectonic structures include the fold-thrust domains with associated shear zones of predominant sinistral sense of shear which are attributed to major collision orogeny during the amalgamation of the arabian-nubian shield (tadesse et al., 1999). the basement precambrian rocks are divided into: (i) the metavolcanic/volcaniclastic dominated lower tsaliet group (~850 ma; teklay, 1997), (ii) metasedimentary rocks containing upper tambien group (835-740 ma, alene et al., 2006; avigad et al., 2007), (iii) dolomite dominated didikama formation, and (iv) younger diamictites and metasandstone/conglomerate containing negash diamictites and shiraro molasses (avigad et al., 2007). the intrusive felsic plutons (synand post-tectonic granitoids) ranging in age from 800 to 520 ma have altered the precambrian rocks and acted as source of heat for the hydrothermal fluids that resulted in base metal and gold mineralization in the region (tadesse et al., 1999; asfawossen et al., 2001; kuester et al., 2009; bheemalingeswara et al., 2012). the basement are overlain by sedimentary rocks of paleozoic (enticho sandstone and edaga arbi tillite), mesozoic (adigrat sandstone, antalo limestone, agula shale and ambaradom sandstone in upward stratigraphic order) and volcanic flood basalts of cenozoic age (beyth, 1972; kazmin, 1978; mengesha et al., 1996; tadesse, 1997). location of the areatogether with precambrian basement rocks, phanerozoic cover (mostly sedimentary and volcanic rocks) and iron hot spots are shown in figure 1. 2.2. geology of the study area it forms part of lithostratigraphy of nw tigray and are dominarted by low grade tsaliet group rocks and mesozoic sedimentary rocks (fig. 2). tsaliet group consists of metavolcanic (mv) rocks of mafic to intermediate composition. they are intruded by younger granitic plutons and overlain by mesozoic sedimentary rocks. the sedimentary rocks are dominated by ferruginous sandstone with thin bands of siltstone and claystone. ferricrete is a conspicuous unit in the area developed on ferruginous sandstone (ebrahim, 2011) which is related to adigrat sandstone (tadesse, 1997). alluvial deposits mostly on sedimentary rocks present in northern and eastern bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 35 issn:2220-184x parts of the area (e.g. about 2m thick in the may-imblay river valley). development of hexagonal / polygonal mud cracks filled with fine sand and with downward tapering are also common. the shire area is well connected by asphalt road from mekelle via adigrat-axum (about 300km). also it is accessible through indesillassie-gondar main road and towards nw through shire indesillassie-kisadgaba-maihanse all-weather road. the area is characterized by arid to semi-arid weather condition with gentle to flat slopes. 2.2.1. basement rocks the basement rocks exposed in many parts of the area are dominated by metavolcanics and show foliated (mafic variety) and massive (intermediate variety) nature. massive variety is exposed in the south and south western part and foliated variety in the central part around maydumu of the study area. the rocks form rugged and ridge topography in the sw part of the study area with moderate to steep tilt towards nw. quartz veins are common in these rocks possibly related to the pale gray to pink colored intrusive post-tectonic granite known as shire granite which is exposed in the northern part of the study area (tadesse, 1997).it is dominated by coarse (>3mm) orthoclase feldspar and quartz and with development of kaolinite along the intrusive contact. 2.2.2. ferruginous sandstone it shows red color due to high content of iron and is intercalated with bands of claystone/siltstone. tadesse (1997) interpreted it equivalent to adigrat sandstone. it covers large area, overlies unconformably the precambrian basement rocks and is characterized by flat lying morphology on both sides of gorgesand is undergoing erosion. in the west side of the study area the rock shows angular unconformity with mv unit making it to have an outlier feature. it varies in thickness from about 30-35m in sw to 10m in ne and shows a gradational contact with the overlying lateritic unit (fig.3).the sandstone is thick, bedded and reddish brown in color having medium to coarse grain size quartz as dominant mineral and followed by orthoclase feldspar and iron hydroxides as cement. alteration of feldspars to kaolinite is seen at many places and being soft it is eroded leaving depressions on the top of the profile. the resistant quartz minerals remain in situ and show alignment fabric indicating sedimentary process (fig.3a & b). development of secondary structures such as cracks and joints common in sandstone which are later filled by iron hydroxides and chert (fig. 3c). in the northern part, there are small patches of pink colored thinly laminated siltstone beds showing conchoidal fracture. bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 36 issn:2220-184x structures like faults, foliations, folds are common in the basement rocks compared to sandstone and related ferricrete. the latter commonly show structures like primary bedding, fractures and cross bedding especially in sandstone unit. the fractures are dense, dip vertically, show northsouth and east-west trend and are filled by quartz, chert and iron oxides. figure 2. geological map of the study area. 2.2.3. ferricrete it is about 2-3m thick, developed on ferruginous sandstoneas part of weathering/ lateritization and extensively exposed in the study area. the vertical section exposed in the quarry site (416000 and 1558000m, fig. 2) shows the transformation with gradational contact from source ferruginous sandstone to iron-rich ferricrete (horizon) and also sub-horizons within ferricrete. ferricrete varies in thickness from 3m to less than a meter particularly in the northern part. at places it is absent because of its removal due to erosion and filling the depressions and gentle slopes downstream. myimblayriver bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 37 issn:2220-184x figure 3. a) dark brown colored ferricrete on top of ferruginous sandstone, b) weathered ferruginous sandstone with white colored aligned quartz minerals, c) fresh ferruginous sandstone with thin iron and silica –rich bands, d) and e) pseudo-pisolitic texture in ferricrete, and f) kaolinite development in ferricrete. figure 4. ferricrete profile showing different sub-horizons in the ferricrete from quarry exposure. bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 38 issn:2220-184x ferricrete horizon is mostly massive and shows reddish brown color due to high content of iron oxides (fig. 3d & f). the top part occurs as loose material showing pisolitic texture and is heavily coated with iron oxides. coarse quartz generally remains the major part of pisolite (fig. 3e). the pseudo-pisolites are widely distributed throughout the ferricrete together with limited development of kaolinite (fig. 3f) indicating variation in lithology locally. different horizons observed in the vertical section and their variations from bottom to top are shown in figure 4. 0 0.5m  iron crust with pseudo-pisolite sub-horizon 0.5 1.5m  nodular and mixed nodular sub-horizon 1.5 3.5m  mottled sub-horizon mottled sub-horizon is represented by weathered part of ferruginous sandstone (saprolith) in which the primary sedimentary structures are preserved and locally intercalated with siltstone.quartz with minor feldspar dominate the rock with iron oxide/hydroxidesfilling the fractures (discordant and concordant). it consists of nodular type quartz grains with few mm to cm size and rounded to sub-rounded shape. the grains are cemented by brown-red iron oxides and slightly indurate dark red ferruginous and clay matrix. intercalation of white clay developed due to the alteration of feldspars with iron oxides is common. the purple red nodular structure is not abundant in the bottom of the mottled sub-horizon but increase very rapidly upward and form a dense framework in the upper part in the section resulting pseudo-pisolitic sub-horizon. it is followed by the development of mixed mottled and nodular sub-horizon(fig.4). mixed mottled sub-horizon is characterized by the breakdown of nodular structures into smaller size spherical, irregular or concretionary shapes with increasing coating by brown color iron oxides. compared to other sub-horizons, banded nature of iron oxide cement is common (fig. 4).this sub-horizon is followed by <1m thick pseudo-pisolitic sub-horizon which is characterised by presence of pisolites, occur as independent and welded variety. the nucleus, mainly quartz, is coated by iron oxides with varying thickness. the rounded and sub-rounded red/brown color pisolites grows thicker due to coating and strongly indurated and welded together producing pseudo-pisolite and colloform textures. with time, the welded ones are breaking down producing independent pisolites which get eroded and accumulated in the stream channels. occurrence of independent pisolites or welded variety seems depend on the varying degree of fragmentation and oxidation (fig.4). though, the iron-rich cement strongly binds the bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 39 issn:2220-184x rounded to sub-rounded pisolites but at places, it becomes cellular type due to removal of cement. 3. methodology 30 rock samples were collected randomly from the field outcrops taking into account the lithologies present and variation within the lithologies particularly ferricrete and sandstone. out of 30 samples, 5 each are from metavolcanic, intrusive granite and ferruginous sandstone rocks and 15 from ferricrete (both lateral and vertical). selected samples were chosen for petrographic and geochemical analysis. 5 rock samples were chosen for thin section preparation (2 from metavolcanics and 3 from ferruginous sandstone) at geological survey of ethiopia, addis ababa. 9 samples from ferricrete were chosen for polished sections preparation at department of earth science, mekelle university. petrographic studies were conducted using transmitted and reflected light microscopes in the petrology laboratory of department of earth science at mekelle university.. 10 rock samples were chosen from ferricrete and sandstone for geochemical analysis. the rock samples were powdered upto minus 200mesh at emd laboratory. after homogenization and coning and quartering, about 100gmof rock powder each were submitted to central laboratory at the geological survey of ethiopia for major and minor element analysis using xrf. the analyses were carried out on pressed pellets using rock standards as reference and control the accuracy of the data. data is given in table 1. apart from these data, 16 surface and borehole samples unpublished xrf data of ferricrete from ezana mining company are also used in the discussion related to geochemical mobility patterns of mobile and immobile elements. 4. results and discussion 4.1. petrography of ferruginous sandstone and ferricrete fine to medium grained ferruginous sandstone typically shows red color in thin section. it is mainly composed of irregular, sub-rounded to angular shaped quartz grains (~70%), orthoclase feldspar (~10%)and ferruginous oxides as cement (~ 20%) (fig.5). quartz shows low relief and low birefringence but does not show wavy extinction.iron oxide/hydroxides serve as a binding material (cement) between mineral grains and rock fragments and seems to have remobilized during the chemical weathering process (fig.5). bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 40 issn:2220-184x figure 5. this section of ferruginous sandstone showing quartz and orthoclase feldspar (a& c, ppl; and b& d; xpl (40x)). thin sections from mottled ferricrete sub-horizon show presence of about 60% quartz. subrounded to roundedgrains are mostlycorroded and affected by later developed cracks. majority of the grains are coated with iron oxides and show brownish red color. there are few fresh grains exhibiting nocracks. these fresh quartz grains are considered to besecondaryin originproduced by dissolution of primary quartz grains and reprecipitation. the polished sections under reflected light microscope show presence of hematite, goethite and limonite. hematite shows light yellow color and is weekly anisotropic. interestingly, hematite does not show any alteration, on the contrary, goethite shows transformation to hematite (fig. 6). hematite is fine-grained, fracture filling and occupies intra-granular and inter-granular space. it produces colloform banding around the nodules. development of cracks and cavities produced due to removal of kaolinite and dissolution of quartz are filled by iron oxide/hydroxide. its gradual enrichment and evolution facilitated development of various iron minerals such as limonite, goethite and hematite. presence of chert as lenses, fracture filling and irregular bodies in sandstone and ferricrete is related to the dissolution of primary quartz and precipitation (figs. 5 and 6). bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 41 issn:2220-184x figure.6. microphotographs polished sections from a) mottled sub-horizon, showing hematite development around kaolinite, secondary quartz and inter-granular space (ppl, 40x); b) mixed nodular sub-horizon, showing inter-granular filling by hematite (ppl, 100x); c) nodular variety; showing thin hematite-rich bands within the sandstone lithic fragment suggesting in-situ modification and concentration (ppl, 100x); and d) pseudopisoliticsub-horizon, showing development of pisolites and fine grained hematite in the matrix and around pisolites (ppl, 100x). note: ps: pseudo-pisolite; and nv: nodular variety. the samples from transition zone (mottled to nodular sub-horizon) indicate remobilization and accumulation of iron oxides/hydroxides. apart from filling the voids, iron hydroxide-rich fragments which are common in this zone show development of hematite. fine bands/layers of hematite are common in addition to fracture filling textures (fig.6). many quartz grains show corrosion effects and gradually become rounded and produced nodular structures. secondary quartz is common. macroscopically recognizable purple-red nodular variety of hematite remains c bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 42 issn:2220-184x the principal ore mineral in these transformations in this zone. association of this nodular variety (nv) with residual zones of the simple mottled variety defines the iron crust with mixed subhorizon. brown-red nodules with yellowish brown rings haves changed to brown pseudopisolites with banded outer shells. the rings developed in a centripetal way at the expense of the cores in the nodules (fig.6). this evolution proceeds as follows: isolation of scales of opaque matrix from the core; diminution of these scales of matrix as soon as the outer shell develops; obliteration of the micro-porosity observed in the core; and replacement of the opaque matrix by hematite. such changes have resulted in the development of white and brown alternating bands in the pisolites (fig. 6; ebrahim, 2011). table.1. range of major and minor oxide values for ferricrete and ferruginous sandstone. table. 2. correlation matrix for major oxides in ferricrete (a total of 16 surface samples). 4.2. geochemistry of ferricrete major and trace element data for ferruginous sandstone and ferricrete are presented in table 1.among the major oxides, fe2o3 shows higher, al2o3 almost remains the same. sio2has lower values in ferricrete compared to the source ferruginous sandstone. sio2 values vary from 74 to17 wt%, fe2o3 8 to 63 wt% and al2o3 13 to 11 wt%. iron and silica contents show significant variation in concentration compared to al value, which remain almost constant in both sandstone and ferricrete. correlation matrix (table 2) indicates negative relationship for iron with si and major oxides ferruginous sandstone (wt. %) ferricrete (wt. %) sio2 74 22-39 al2o3 13 16-25 fe2o3 8 30-50 k2o 0.05 0-0.5 tio2 0.37 0.7-2 p2o5 0.036 0.1-0.7 mno 0.0159 0-0.3 fe2o3 al2o3+sio2 sio2 al2o3 al2o3+fe2o3 fe2o3 1 al2o3+sio2 -0.940 1 sio2 -0.892 0.952 1 al2o3 -0.735 0.776 0.545 1 al2o3+fe2o3 0.951 -0.856 -0.899 -0.491 1 bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 43 issn:2220-184x al; and positive relationship though not very strong between si and al. relatively higher mobility of si compared to al is related to secondary quartz produced due to dissolution of primary quartz (si), its removal and precipitation (fig. 6a) compared to kaolinite (al) which is partially removed by erosion not by dissolution (fig. 3f). figure 7. variation in fe2o3, al2o3, and sio2wt% values in ferricrete with depth (test pit data from ezana). note: lines at 0.5 and 1.5m depth indicate approx. sub-horizon boundary. major oxides data of three drill holes maximum about 4.5m deep passing through the mottled sub-horizon (fig.7) indicate significant variation in both fe2o3andsio2 concentration values between 3.25-4.25m compared to 0.25-0.5m depth. al2o3 on the other hand almost remains constant with minor variation from top to bottom in the section. the sub-horizons shown in the figure 7 compare well with that of ferricrete profile shown in figure 3, which is about 3mthick and exposed in the quarry site in the central part of the study area. since the sub-horizons thickness is more or less comparable with that of test pits (borehole) log data, it is possible to relate the elemental concentrations and their geochemical behavior along ferricrete profile. correlation matrix (table 2) of surface ferricrete samples data also correlate well with the test bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 44 issn:2220-184x pits data. compared to others, mottled sub-horizon varies in thickness from less than a meter to more than 3m (fig. 7). among trace elements, vanadium shows significant values > 1300 ppm in ferrictere compared about 300ppm in source sandstone. these values also tallies well with ezana data in which vanadium shows values > 2500ppm. apart from v, zirconium values range upto 222 ppm and co upto 129 ppm (ebrahim, 2011). 4.3. development of ferricrete petrographic together with field data indicate that ferruginous sandstone forms the source for the development of ferricrete as part of lateritization and residual enrichment. different sub-horizons noted in the ferricrete profile based on mineralogy and textures compare well with the laterites (ferricretes) reported elsewhere developed on ferruginous sandstone (nahod et al., 1977; tardy and nahod, 1985; ramakrishan and tiwari, 2006; ramanaidu et al., 1996). 4.3.1. ferruginous sandstone to mottled sub-horizon transition from red colored ferruginous sandstone to mottled sub-horizon lateritization is progressive and is indicated by a) increase of coloration and indurations; b) preservation of the primary sedimentary structure; and c) complete and/or partial epigenesis of the components of parent rock minerals (quartz and orthoclase feldspar). the ferricrete with mottled sub-horizon is originated directly from the ferruginous sandstone with about 15-20% iron oxides/hydroxides as cement and iron oxides supplied by the percolating solutions during weathering. the major process in the transformation of ferruginous sandstone to mottled sub-horizon is the breakdown of the rock into lithic fragments and chemical breakdown of orthoclase feldspar mineral structures and partial dissolution of quartz. this will produce a network of channels and large tubular voids of large diameters (cm) in which kaolinite produced due to breakdown of feldspar and iron-rich cement material can accumulate. 4.3.2. mottled to nodular sub-horizon continued weathering of mottled sub-horizon has produced indurated nodular sub-horizon. it may be related to two processes. 1) the massive iron crust with strong iron-rich cement (mottled sub-horizon) gradually develops into nodules or concretions by partial dissolution of quartz grains and remobilization of iron-rich cement. this is well indicated in the petrographic study where the voids created by the partial dissolution of quartz and breakdown of feldsparsare partially replaced by kaolinite-ferruginous material (figs. 3, 4& 6). thus the nodular and concretionary type sub-horizon is produced with colloform and open space filling textures. 2) bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 45 issn:2220-184x voids developed by leaching of the quartz serve as secondary "reception" structures for kaolinite. this is because the original ferruginous sandstone is devoid of kaolinite and the latter is the result of the chemical breakdown of orthoclase feldspar present in sandstone (fig. 6). kaolinite is later replaced and progressively enriched in iron thus producing fine-grained iron ore mineral characterized by small pore size (<< 0.1 mm). in addition, in this sub-horizon, there is an accumulation of secondary quartz developed by precipitation from the percolating silica-rich solutions from the upper parts of the profiles (fig. 6). 4.3.3. nodular to pseudo-pisolitic sub-horizon the mixed nodular sub-horizon further evolved into pseudo-pisolitic possibly due to the following geochemical changes. removal of si in the mixed nodular sub-horizon and the subsequent modifications affected the ferruginous components (iron oxides/hydroxides) and kaolinite in the iron and kaolinite matrix. the re-organization of indurated mixed nodular subhorizon takes place by insitu centripetal way of accumulation of iron oxide and removal of kaolinite and development of pisolitic structures. continuous reorganization into pseudo-pisolite is accompanied by the gradual removal of kaolinite and further dissolution of the nodules and mobilization of iron oxide/hydroxides. this leads to the reduction in size of the coarse nodular structure into smaller size pisolites and thus producing the pseudo-pisolitic textures and pseudopisolitic sub-horizon. presence of poor matrix in this horizon compared to other sub-horizons exposed the pisolites to erosion and accumulated in the stream channels. behavior of fe, al and si in the vertical sections suggests that residual enrichment of iron is significant. movement of iron oxides downward from the top sub-horizons facilitates coating and thus accumulation of iron around the nodular fragments. mobility rate of iron being low compared to silica and aluminum gradually accumulated with time and favorable conditions. during which the iron oxide/hydroxides have modified from hydroxide (limonite, goethite) to hematite (iron oxide). thus, by the combination of absolute and relative accumulations of iron produced ferricrete from the ferruginous sandstone. but during lateritization, precipitation of the silica-rich solutions derived from dissolution of primary quartz produced secondary quartz, chert periodically, thus reducing the size regularly and finally reaches to smaller sizes in the pseudopisolitic sub-profile. al on the other hand oscillates between kaolinite and iron oxy-hydroxides where it will be a substitute and fe oscillates between dissolved and crystallized forms only. bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 46 issn:2220-184x 4.4. mineral paragenetic sequence the mineral that are involved in the lateritization of sandstone to iron crust (ferricrete) are hematite, goethite, limonite, ochre, quartz, feldspar, kaolinite, chert and iron oxy-hydroxide cement. on the basis of field observation and petrographic study following paragenetic sequence is proposed for the lateritic iron deposit and shown in table 3. table 3. paragenetic sequences of the minerals in ferricrete formation (note: thickness of the line indicates concentration of the mineral). 4.5. comment on genesis hematite, goethite, limonite and ochre are common minerals in the ferricrete. goethite is seen converted to hematite instead of hematite to goethite as hematite does not show any alteration to goethite as expected in an oxidizing weathering condition. paragenetic sequence of iron minerals seems to have developed in the following manner. the ferruginous sandstone originally may be devoid of hydroxides of iron (like goethite) because of the transformation of metastable goethite formed in water into hematite during long burial digenesis of sediments of tertiary to paleozoic in age (tardy and nahod, 1985) and this is noticed by not well developed goethite in the polished sections; b) goethite does not replace hematite because the temperature is relatively high and do not favor hydration of hematite to goethite in the iron crust particularly that occurs at the top of the profile; and c) the relative stability of goethite and hematite depends on many factors such as grain size effect. if the crystal of hematite is grater or equal to the grain size of minerals stage 1 (mottled sub-horizon) stage 2 (nodular sub-horizon) stage 3 (pseudo-pisolitic sub-horizon) quartz orthoclase feldspar iron-rich cement limonite kaolinite secondary quartz goethite hematite ochre bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 47 issn:2220-184x the crystal of goethite, hematite is stable than goethite in water but in the reverse situation goethite is stable but in the case concretion and nodules in iron crust (ferricrete) formation both minerals do not from large crystals and appear as a very tiny particle size (tardy and nahod, 1985). so, the governing condition for stability of these minerals mainly is dehydration and water activity compared to the particle size. if iron is released from silicates and from other primary source in water then it will form goethite; if the solubility product of goethite is excess than that of ferri-hydrite. ferri-hydrite is formed and transformed to hematite through dehydration or to goethite through dissolution; the factor that favors ferri-hydrite formation will also favor the formation of hematite by high temperature by dehydration. the factors controlling the formation of ferri-hydrite in solution are: a) rapid release of fe; b) low concentration of organic compound which complexes iron (allowing concentration of inorganic fe 3+ ); c) iron release in ferruginous sandstone being high because the large pore size (with iron hydroxide matrix) favor increasing activity of water; d)presence of negligible amounts of organic matter (or organic compounds) in thesource ferruginous sandstone could be one of the reasons for the stability of hematite over goethite during ferricrete formation; and e) equilibrium condition involving water activity, pore size and nodule formation(tardy and nahod, 1985; nahod et al., 1977; tardy et al., 1991). 5. conclusion ferricrete developed on ferruginous sandstone (adigrat? of mesozoic) is composed of a succession of different sub-horizons, namely mottled, mixed nodular and pseudo-pisolitic. fe2o3 content in ferricrete varies from 30-50 wt%, al2o3 upto 25% and sio2 upto 30%. on the basis of the field and petrographic data, the successive sub-horizons in the ferricrete are noted as: massive structure (iron pan) and dismantled pisolites upper mixed horizon (medium nodular)lower mixed horizon (coarse nodular)  mottled horizon (saprolitic) the ferruginous sandstone. ferricrete horizon shows gradational contact with the source ferruginous sandstone. gradual removal of kaolinite and silica facilitated enrichment of iron oxide/hydroxides in the form of coating around lithic fragments, nodular, pisolitic etc. iron hydroxides, limonite and goethite with time are changing to hematite due to dehydration. hematite is fine grained and shows textures like colloform banding, fracture filling, dissemination etc. geochemical behavior of major elements clearly indicates the role of climate, bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 48 issn:2220-184x eh, ph, ionic activity etc factors in the development of laterite development. according to an approximate estimate the tonnage of the reserve is above 100mt with an average grade of about 35-40wt% iron and among trace elements, v, zr and co shows relative enrichment upto 0.3wt% (ebrahim, 2011). 6. acknowledgement ibrahim nesro is grateful to ministry of education, ethiopia for partial fund granted as part of post graduate research. authors duly acknowledge mekelle university for granting a research fund through the project on “geological and geochemical study of lateritic iron deposit near mentebteb, shiraro, northern tigray, ethiopia (cncs/rb/34/2011)” which helped to analyze few samples from shire. we are also very thankful to ezana mining plc for providing us borehole data. authors duly acknowledge the reviewers dr. n. siddaiah and dr. anbarasu for providing useful comments and helping to improve the paper. 7. references alene, m., jenkin, g.r.t., leng, m. j & darbyshire, f.d.p. 2006. the tambiengroup, ethiopia: an early cryogenian (ca. 800-735 ma) neoproterozoic sequence in the arabian-nubian shield. precambrian research,147: 79-99. asfawossen, a., barbey, p & gleizes, g. 2001. the precambrian geology of ethiopia: a review. africa geoscience review, 8: 271-288. avigad, d., stern, r.j., beyth, m., miller, n & mcwilliams, m.o. 2007. detrital zircon u-pb geochronology of cryogenian diamictites and lower paleozoic sandstone in ethiopia (tigrai): age constraints on neoproterozoic glaciation and crustal evolution of the southern arabian-nubian shield. precambrian research,154: 88-106. beyth, m. 1972. paleozoic-mesozoic sedimentary basin of mekelle outlier, northern ethiopia. aapg bull., 56: 2426-2439. bheemalingeswara konka, solomon gebreselassie & kassa amare, 2012. shear zone controlled base metal mineralization around abraha weatsebaha-adidesta and hawzein, tigray region, northern ethiopia.momona ethiopian journal of science, 4(1): 3-28. ebrahim nesro hussen. 2011. geology and geochemistry of lateritic iron deposit in mydmu area near shire indessilassie, western tigray, ethiopia. m.sc, thesis, department of earth sciences, mekelle university, mekelle, ethiopia, 130p (unpubl). bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 49 issn:2220-184x gebreselassie, s., bheemalingeswara konka & fiseha adhanom. 2012. geology and characteristics of metalimestone-hosted iron deposit near negash, tigray, northern ethiopia. international journal of earth sciences and engineering, 5(4): (in press). kazmin, v. 1978. geology of ethiopian basement and possible relation between the mozambique and the red sea belts. egyptian journal of geology,22: 73-86. dirk küster., romer, rolf l., dandena tolessa., desta zerihun., bheemalingeswara, k.,frank melcher & thomas oberthür. 2009. the kenticha rare-element pegmatite, ethiopia: internal differentiation, u-pb age and ta mineralization. mineralium deposita, 44(7): 723-750. mengesha, t., tadiwos, c & workneh, h. 1996. the geological map of ethiopia, 1:2,000,000 scale, 2 nd edition, eigs, addis ababa. nahon, d., janot, c., karpoff, a. m., paquet, h & tardy, y. 1977. mineralogy, petrography and structures of iron crusts (ferricretes) developed on sandstones in the western part of senegal. geoderma, 19: 263-277. ramakrishnan, d & tiwari, k.c. 2006. calcretized ferricrete around the jaisalmer area, thar desert, india: their chemistry, mineralogy, micromorphology and genesis.turkish journal of earth sciences (turkish journal of earth sciences), 15:211-223. ramanaidu, e., nahon, d., decarreau, a & melfi, a.j. 1996. hematite and goethite from durycrusts developed by lateritic chemical weathering of precambrian banded iron formations, minas gerais, brazil.clays and clay minerals, 44(1):22-31. tadesses, s. 2006. mineral resources potential of ethiopia. addis ababa, 212p. tadesse, t. 1997.the geology of axum area.geological survey of ethiopia, memorial no 1, addis ababa. tadesse, t., hoshino, m & sawada, y. 1999.geochemistry of lowgrade metavolcanic rocks from the pan-african of the axum area, northern ethiopia. precambrian research, 99: 101124. tardy, y & nahon, d. 1985.geochemistry of ferricretes, stability of al-goethite, al-hematite and fe-kaolinite in bauxites and ferricrete: an approach to the mechanism of concretion formation. amer. j. sci., 286: 865-903. tardy, y., kobilsex, b & paquet, h. 1991. mineralogical composition and geographical distribution of african and brazilian periatlantic laterites. the influence of continental bheemalingeswara, k., solomon, g and ebrahim, n.h (mejs) volume 5(1):32-50, 2013 © cncs, mekelle university 50 issn:2220-184x drift and tropical paleoclimates during the past 150 million years and implications for india and australia. journal of african earth sciences, 12(1): 283-295. teklay, m. 1997. petrology, geochemistry, and geochronology of neoproterzoic magmatic arc rocks from eritrea: implications for crustal evolution in the southern nubian shield. memoir eritrea department of mines, 1:125. wondafrash mammo ghebre. 2010. geology and mineralization of bikilal phosphate deposit, western ethiopia, implication and outline of gabbro intrusion to east africa zone. iranian journal of earth sciences, 2:158-167. microsoft word 1. cover pages dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 the positive effect of micro-dams for groundwater enhancement: a case study around tsinkanet and rubafeleg area, tigray, northern ethiopia) *dessie nedaw 1 and kristine walraevens 2 1mekelle university, ethiopia, college of natural and computational sciences, department of applied geology, p.o.box 231, mekelle (*dessienedaw@yahoo.com) 2ghent university, belgium, laboratory for applied geology, department of geology and soil science, krijgslaan 281 – 58 – b – 9000 gent. abstract the government of tigray regional state, northern ethiopia has been conducting a massive construction of micro-dams (small reservoirs) in order to decrease the rainfall dependency and alleviate food insecurity in drought prone areas of the region. tsenkanet and rubafeleg reservoirs are examples of this endeavor. the purpose of this investigation is to evaluate the role of these micro-dams in enhancing the surrounding groundwater by artificial recharge. in this study the physical characteristics of the reservoir are discussed including the groundwater surface water relationship with respect to water level elevation and also hydro-chemical composition. six water samples have been analyzed. samples are taken after rinsing the plastic bottles with distilled water and the sample to be taken. one surface water sample from each reservoir and one groundwater samples from each well next to each reservoir has been collected. moreover, one sample from spring and one from river has been analyzed. the chemical composition of the reservoir water and the surrounding groundwater seem to suggest a similar origin and to be resulting from similar hydro-chemical processes. the chemical composition of all samples is found to be of the cahco3 type, which could be explained as resulting from precipitation water in which the mineral calcite has been dissolved. both the topographic evidence and the water level monitoring data has confirmed the feeding of the reservoir to the near by shallow groundwater system. quantifying the amount of groundwater accretion by the use of modeling and water balance method is recommended. keywords: groundwater, surface water, topography, water level, type, hardness, class. 1. introduction water scarcity and unwise management is a global concern especially in sub-saharan countries. global fresh water demand is alarmingly increasing with increase in population and civilization. as industrial, agricultural and domestic pollution threaten existing supplies – water becomes increasingly precious resource. ethiopia surface water and groundwater resources have been regarded as high giving a name to the country as the water tower of east africa (said, 1993). this is factually true when considering half of the country, particularly the western and south western part of the country. mekelle university issn: 2073-073x 59 mailto:*dessienedaw@yahoo.com dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 the endowment can be used for productive purpose that can transform the countries socio economy (selashi, 2007). unfortunately its uneven distribution in space and time coupled with poor management and development of the resource lead the country to a repeated famine resulting from drought (fao, 2005). the tigray regional state is in the northern part of the country, where drought and subsequent famine was common in the past. geba catchment, the project area is characterized by intermittent rivers which are dry 8 to 9 months with arid and semi arid climatic condition. the main socio-economic activity in the area is rain fed agriculture which directly linked to the erratic rainfall. to alleviate this rainfall dependency which is full of uncertainty the regional government has devised a mechanism by which it can supplement the rain fed agriculture with irrigation by constructing micro-dams. this task was mainly assigned for a governmental organization named co-seart (commission for sustainable agriculture and environmental rehabilitation of tigray). the activity of the organization has been stopped after constructing 60 micro-dams because it has been believed that they are less effective in supporting the rain fed agriculture through small scale irrigation schemes for institutional, technical and socio economic reasons. therefore the purpose of this investigation was to evaluate the role of these seemingly failed micro-dams in enhancing the surrounding groundwater system by artificial recharge. the specific objective of this study were to investigate first the interaction of these reservoir with the surrounding groundwater and if possible to quantify the total amount of recharge from the reservoir to the surrounding groundwater system. 2. methodology to achieve the above mentioned objective three wells labeled as tsinkanet well 1 (tsw1), tsinkanet well 2 (tsw2) and rubafeleg well (rfw) and two micro dams labeled as rubafeleg dam (rfl) and tsinkanet dam (tsl) have been closely examined. the water level fluctuation (both in the dams and wells) has been monitored for nearly two years with the average interval of 2 hours, in order to see change of the water level in response to rainfall and recharge. as the general purpose is to monitor the interaction between the reservoirs and the groundwater system the impact of irrigation was not considered in this investigation. the water level both in the well and the reservoir is monitored by td divers, by which a continuous record of temperature and water depth is recorded from november 2004 to december 2006 with an interval of 2 hours. in mekelle university issn: 2073-073x 60 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 order to be accurate on the elevation difference between measuring points of the diver altimetry leveling has been conducted. water samples collected from tsinkanet and rubafeleg on jan 6, 2006 and march 14, 2006 have been analyzed in belgium and ethiopia. four water samples were analyzed in the laboratory of applied geology, department of geology and soil sciences, university of ghent, belgium and two samples were analyzed at department of earth science, mekelle university. for the ca++, mg++, na+, k+, fe, mn, and si varian aas has been used and for hco3 titration method is used and no3, so4, cl, and po4 uv spectrophotometer is used. the accuracy of the analysis has been tested using ionic balance (appelo and postma, 1996). in all but one the balance is found to be less than 5%. this indicates that the analysis is sufficiently accurate. in order to interpret and classify the water a new classification scheme developed by stuyfzand (1986) is adopted. the classification starts with main type based on chloride concentration, then each main type is subdivided to type based on total hardness, then each type is further subdivided into sub type based on the proportional share of main constituents in the sum of cations and anions in meq/l, finally each sub type is further classified to classes by using the following formula (na + k + mg) corrected = (na + k + mg) measured – 1.061 cl (meq/l) 3. location and accessibility geba-catchment has an area 5133 km2. the elevation ranges from 955 m a.m.s.l to 3295 m a.m.s.l. the mean elevation has been found to be 2146 m, a.m.s.l. entire geba catchment is found between 39°30’ to 40°00’ e (longitude.) and 13°45’ to14°15 n (latitude) figure 1. tsinkanet and rubafeleg area are found in the upper catchment of geba along the west and east boundaries respectively (figure 1). in both areas there is a reservoir on upstream side and shallow hand dug wells in the command areas. the utm location of the reservoirs and the shallow hand dug wells where monitoring is conducted is shown on table 1.as one can see from the table the monitoring well at tsinkanet is 400 meter west of the reservoir where as the monitoring well at rubafeleg is more than 1 km north of the reservoirs. both reservoirs are not more than 1 km2 area, and there depth is not more than 10 meter. tsinkanet area is found between (561500 – 555500 utme and 1552100 – 1546000 utmn) and rubafeleg area is found between (581700 – 575700 utme and 1543000 – 1537500 utmn). mekelle university issn: 2073-073x 61 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 the study area is accessible by all weather roads running from hawzen to senkata and from atsbi to dera. table 1. utm location of water points used for monitoring. name of water point tsinkanet well 1(monitoring well) (tsw1) tsinkanet well 2 (tsw2) tsinkanet (center of dam axis) (tsl) rubafeleg well (rfw) rubafeleg (center of dam axis) rfl utmn 1549139 1549080 1541634 1540500 location utme 558303 558723 578715 578700 igure1. location map of geba catchment, tsinkanet and rubafeleg area (usgs, 2004). tsinkanet rubafeleg f mekelle university issn: 2073-073x 62 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 4. geology and hydrogeology of the study area brian age, composed of the study area is mainly characterized by basement complex of precam meta-volcanics and meta-sediments (kazmin, 1978). these are exposed in most parts of the mapped area. figure 2. geological map of northern geba catchment ( modified after tesfamicheal gebreyohannes et al., 2009) mekelle university issn: 2073-073x 63 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 at the eastern mos is exposed. in the s . results and discussion topographic and shuttle radar topographic mission topographic position is one of the governing factors that control the direction of groundwater ervoir and the surrounding groundwater was being monitored since d in the micro-dam is always higher than that of the wells during the – eral trend of water level change both in the reservoir and in the t part and along the northwestern part paleozoic sandstone southwestern part a younger granite intrusion is mapped cross cutting the basement complex as shown in figure 3. since the area is mainly characterized by crystalline metamorphic rocks, the groundwater availability and movement is mainly controlled by fractures and weathering zones. the main water supply for drinking and small scale irrigation is the groundwater tapped from boreholes to a maximum depth of 50 m and hand dug well with a maximum depth of 10 meter. in tsinkanet area the reservoir is mainly characterized by enticho sandstone, with a thicknes not more than a couple of meters. at the command area the sandstone thins out and the underlying metavolcanic rock is exposed. in rubafeleg area both the reservoir and the command area are characterized by metamorphic rocks mainly metavolcanic and metasediments. 5 5.1 geomorphologic analysis from (srtm, 2004) data flow. in the area the geographic location of the reservoir and the aquifer system is in a suitable location enabling the reservoir to feed the groundwater. in addition the high degree of fracturing and weathering also encourage the down gradient flow of the seepage water. accordingly the subsurface water downstream to the reservoir is under favorable location for groundwater recharge figures 3 and 4. 5.2. water level analysis water level both in the res late 2004 in tsinkanet and rubafeleg area. monitoring has been conducted for more than two years till december 2006. as it can be seen on the following graphs (figure 6 & 7) the following observations are seen. – the hea recorded period. moreover the gen well with respect to time is more or less similar. mekelle university issn: 2073-073x 64 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 figure 3. tsinkanet area topography. figure 4. rubafeleg area topography mekelle university issn: 2073-073x 65 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 – the water level in the groundwater is generally found to rise, indicating a continuous accretion of groundwater from the reservoir even though the water in the wells is being continuously used for irrigation particularly during the dry season in tsinkanet area. as the scope of this paper is to indicate the unseen role of the reservoirs as a groundwater recharging mechanism the focus is in the general trend not on quantifying the volume of water recharged. – marshy areas are developed downstream of reservoir. the above observation indicates that the surface water in the reservoir to interact with the surrounding groundwater. moreover the surface water is feeding the groundwater down stream enhancing the groundwater system as indicated by development of wet area down stream figure 5. figure 5. seepage downstream of rubafeleg dam (top, rubafeleg dam and bottom, south of the dam, in the command area) mekelle university issn: 2073-073x 66 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 figure 6. general water level rise on tsinkanet well 1 (tsw1). (from nov. 2004 to dec. 2006) figure 7. tsinkanet well 1 (tsw1) being recharged by tsinkanet micro dam (tsl). (evidence from water level data from june 2005 to november 2006) mekelle university issn: 2073-073x 67 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 table 2. chemical characteristics of the samples from rubafeleg and tsinkanet. sample id tsw2 tsl rfw rfl rfr* rfs** location (utm) 558649 558723 578715 578700 578615 578660 1548515 1549080 1541634 1540500 1442465 1541918 ph 7.2 7.4 7.4 7.5 ---- ec (µs/cm) 202 250 454 181 ---- na (ppm) 13.65 9.9 17.38 5.92 20 18 k (ppm) 1.51 3.75 0.46 1.66 4 3 ca (ppm) 23.28 26.8 63.83 26.5 22 13 mg (ppm) 6.08 9.45 10.45 5.38 14 15 fe (ppm) 0.29 0.21 0.18 0.11 1 1 mn (ppm) nil 0.01 nil 0.01 0 0 nh4 (ppm) 0.36 0.21 nil 0.17 ---- zn (ppm) 0.02 0.02 nil 0.01 0 0 cl (ppm) 8.39 13.92 17.89 7.95 39.48 9.69 so4 (ppm) 14.82 33.11 21.63 9.28 26.03 79.28 no3 (ppm) 0.94 0.38 12 0.2 ---- no2 (ppm) 0.02 0.14 0.02 0.02 ---- hco3 (ppm) 95.16 128 230.58 99.43 170.32 152.37 po4 (ppm) 0.03 2.89 2.89 2.89 4.545 5.01 si (ppm) 8.03 <7 11.74 <7 ---- * rfr is rubafeleg river, analyzed at mekelle university, earth science lab. ** rfs is rubafeleg spring, analyzed at mekelle university, earth science lab. 5.3. hydro-chemical analysis 5.3.1. general chemical characteristics of the water samples in the area: the general chemical composition of the water samples has been described with the help of table and graph here. four samples have been analyzed in applied geology laboratory, department of geology and soil sciences, university of ghent, belgium for major and minor ions. mekelle university issn: 2073-073x 68 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 additional two samples were analyzed in the department of earth science, mekelle university. the results of the analysis are shown on table 2 and figure 8. the samples are believed to be sufficient considering the size of the target area and the scope of the investigation. two samples are from rubafeleg, from the dam and borehole and two samples are from tsinkanet, again from dam and hand-dug well. the other two samples are from river and spring in rubafeleg area. as it has been depicted in table 2, the general characteristics of the water sample are more or less similar indicating similar origin and trend. 5.3.1.2. stuyfzand classification of the water samples: to further verify similarities of the water samples from the dam and the groundwater stuyfzand classification method has been used (stuyfzand, 1986). accordingly they are divided into the following. figure 8. chemical composition of the samples collected from water points. -1. main type: it is a function of cl content. the chloride concentration of the samples ranges from 7.95 mg/l to 17.9 mg/l. this indicates all the samples to have a cl concentration of less than 150 mg/l, accordingly they are grouped as fresh (f) (table 3). mekelle university issn: 2073-073x 69 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 table 3. main type classification of water samples. sample id rfl rfw tsl tsw2 rfr rfs -cl concentration (mg/l) 7.95 17.89 13.92 8.39 39.48 9.69 2. type (hardness code): this is derived from the total hardness calculated from the following formula. th = 2.5 (ca) + 4.1 (mg) where th is total hardness in mg/l and (ca) and (mg) are also in mg/l accordingly the hardness of the samples is tabulated table 4 and found that they range from soft to hard water. table 4. type classification of the water samples. rfr* rfs*sample id tsw2 tsl rfw rfl 63.83 22 13 ca (ppm) 23.28 26.8 26.5 10.45 14 15 mg (ppm) 6.08 9.45 5.38 hardness in mg/l 83.128 105.745 202.42 88.308 112.4 94 hardness in mmol/l 0.83 1.06 2.02 0.88 1.12 0.94 hardness name soft hard moderately hard soft moderately hard soft hardness code 0 2 1 0 1 0 table 5. milliequivalents and the proportions for major cations and anions. sample id units ions ca +mg (na+k)+nh (al+h)+(fe+mn) hco +co so +(no +no ) cl 4 3 3 4 3 2 meq 1.76 0.31 0 1.63 0.19 0.22 rfl % 85.02 14.98 0 79.9 9.3 10.8 meq 4.05 0.77 0.01 3.78 0.64 0.51 rfw % 83.9 15.9 0.2 76.7 13 10.3 meq 2.12 0.54 0.01 2.11 0.7 0.39 tsl % 79.4 20.2 0.4 65.9 21.9 12.2 meq 1.66 0.65 0.01 1.56 0.32 0.24 tsw2 % 71.6 28 0.4 73.6 15.1 11.3 meq 2.25 0.97 0.036 2.8 0.54 1.11 rfr % 69.1 29.8 1.1 62.93 12.13 24.94 meq 1.88 0.856 0.036 2.5 1.65 0.27 rfs % 67.82 30.88 1.3 56.56 37.33 6.11 mekelle university issn: 2073-073x 70 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 2. sub type: this is quite important to recognize the processes that have determined the water quality. the milliequivalent concentration has been converted to proportion as cations group and anions group. accordingly all the samples have been found to be cahco3 type (table 5). 3. class (cation exchange code) the code indicates whether the cation exchange has taken place or not and also the nature of the exchange. the sum of na, k and mg (meq/l) is corrected for the seawater contribution, determined from the clcontent. (na + k + mg) = (na + k + mg) measured – 1.061 cl (meq/l) (see table 6) corrected table 6. class classification of the water samples. sample id measured (meq) 1.061*(cl) (meq) corrected name code( )cl2 1(na+k+mg) (na+k+mg) rfl 0.74 0.23 0.51 -0.33 (na + k+ mg) surplus + rfw 1.63 0.54 1.09 -0.5 (na + k+ mg) surplus + tsl 1.31 0.41 0.9 -0.44 (na + k+ mg) surplus + tsw2 1.13 0.25 0.86 -0.34 (na + k+ mg) surplus + rfr 2.12 1.18 0.94 -0.74 (na + k+ mg) surplus + rfs 2.086 0.29 1.76 -0.38 (na + k+ mg) surplus + the stuyfzand (1986) classification has been used to investigate sea water intrusion but as the author suggested it can also be used to determine natural waters which has undergone different processes. in general all the water samples fall in more or less similar group in which among cations ca is dominant and among anions hco3 is dominant. rubafeleg well has relatively higher electrical conductivity indicating that it is truly groundwater as compared to the others. higher no3 is observed in this well that could be explained with its relative position with respect to the toilet nearby. from the above classification one can see that in both rubafeleg and mekelle university issn: 2073-073x 71 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 tsinkanet areas the water from different sources fall in the same group with more or less similar chemical composition indicating a relationship between the dam water and the groundwater. the chemical composition of the water could be explained by dissociation of silicate minerals mainly plagioclase feldspar and/or k-feldspars as the groundwater flows through the surrounding area or as base flow water into the micro-dam. but this should be further verified by making detailed investigation on the geochemistry of the surrounding rocks. 6. conclusion the study tries to justify the interaction between the surface water in tsinaknet and rubafeleg reservoir, from physiographic, water level and hydrochemical point of view it has been found that the surface water is interacting with the surrounding groundwater. in addition the reservoirs constructed for the purpose of surface water harvesting are found to enhance the groundwater system downstream encouraging the use of small hand-dug wells managed by a single family for their subsistence farming. the study further recommend to make an investigation to quantify the quantitative recharge calculation to be made to further understand the role of this reservoir as groundwater enhancing structure using modeling approach. moreover a detailed geochemical investigation will further consolidate the findings of the research from hydrochemical point of view. 7. references appelo, c.a.j. & postma, d. 1996. geochemistry, groundwater and pollution. a.a balkema, rotterdam, fao. 2005. fao’s information system for water and agriculture (aquastat). http://www.fao.org/nr/water/aquastat/countries/ethiopia/index.stm kazmin, v. 1978. geology of ethiopian basement and possible relation between the mozambique and the red sea belts. egyptian journal geology, 22: 73-86. said, r. 1993. the river nile, geology, hydrology and utilisation. pergamon press, england, pp. 282. seleshi, b. 2007. water challenges, innovations and interventions for ethiopia, think tank paper on water resource, pp. 10. mekelle university issn: 2073-073x 72 dessie n. & kristine w. (mejs) volume 1 (1): 59 – 73, 2009 stuyfzand, p.j. 1986. a new hydrochemical classification of water types; principles and application to the coastal dunes aquifer system of the netherlands. proceedings, 9th salt water intrusion meeting, delft, 641 – 655. tesfamichael, g, f., de smidt., hagos, m., amare, k., kabeto, k., hussein, a., jan nyssen., bauer, h., moeyersons, j., deckers, j. & taha, n. 2009. tigray livelihood, large scale geological mapping of the geba basin, northern ethiopia. usgs, 2004. shuttle radar topographic mission, srtm.usgs.gov. mekelle university issn: 2073-073x 73 © cncs mekelle university petrographic studies of rocks from the chesapeake bay impact structure (usa): implication for moderate shock pressures in sedimentary breccias kassa amare department of earth science, college of natural and computational sciences, mekelle university, mekelle, ethiopia (kassamare@yahoo.com) abstract shock petrographic investigations were carried out on samples collected from drill cores from the chesapeake bay impact structure (usa). the late eocene chesapeake impact structure is, at 85 km diameter, currently the largest impact structure known in the united states, buried at shallow to moderate depths beneath continental margin sediments underneath southeastern virginia. to better define the variety of the samples collected from the shallow drill cores and the shock degrees experienced by the target rocks and breccias in the chesapeake impact crater, thin section analyses were conducted on more than 50 samples from the various zones of the impact structure. the study involves measurements of the orientations of planar deformation features (pdfs) using a universal stage attached to a petrographic microscope. the aim of this study is to determine the shock pressures of various clasts in the shallow breccia fill of the crater. as a result, we note that the overwhelming numbers of shocked grains, which are now present in the sedimentary breccia, are derived from the basement granitoids. our studies involved samples from four shallow drill cores (exmore, windmill point, kiptopeke, and newsport news).the breccia fill is termed the exmore breccia, which is dominated by particulates of silt, shocked and unshocked granitic fragments, shale, clay, and free shocked quartz grains. the kiptopke and windmill point samples contained rare fragments showing a variety of different shock effects, whereas the newporte news samples, show several fragments and impact melt with the evidence shock metamorphism was noted. the most abundantly observed shock indicators are shock fracturing, indicative of shock pressures of less than about 10 gpa, as well as 1-2 sets of pdfs in quartz grains, which is indicative of moderate shock pressures of up to about 20 or 25 gpa. key words: chesapeake bay crater, pdfs, shock pressure, universal stage, impact structure. 1. introduction impact cratering is a rapid surface-modification process, which happens when a large meteoroid (asteroid or comet) hits a planet or a satellite (e.g., koeberl, 1998). besides, it is a unique geological process in which vast amounts of energy are released in a small area in a very short time (e.g., grieve, 1990). impact craters on earth are produced by the hypervelocity impact of asteroids and comets at a velocity between 11 and 72 km/s and the magnitude of the energy release depends mainly on the speed and size of the impacting body (grieve, 1991). as a result, impact events have generated large crustal disturbances, produced huge volume of igneous rocks, kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 129 formed major ore deposits, and participated in at least one major biological extinction event (e.g., french, 1998; montanari and koeberl, 2000). today, it has been realized that the terrestrial impact structures are more abundant, larger, older, more geologically complex and economically important and even more biologically significant than anyone would have predicated a few decades ago (e.g., grieve, 1991; french, 1998). in addition, impact processes are now considered to have played a vital role in planetary formation, through accretion of large bodies (the protoplanets) as the result of collisions between smaller bodies, the so-called planetesimals (e.g., melosh, 1989; taylor, 1992). about 175 terrestrial impact craters have been discovered so far (2009) and several new craters are discovered each year (grieve, 1991, see also earth impact database, 2010:www.unb.ca/passc/impact database/). the impact craters on earth range in age from a few thousands to almost two billion years (grieve, 1990, 1991; french, 1998). the known impact structures ranges from circular bowls only a few kilometers in diameter to a large complex structure more than 200 km in diameter and as old as 2 ga. some of the preserved terrestrial craters on earth show varying stages of preservation and exposure, ranging from deeply eroded, e.g., vredefort, south africa, to those that have well preserved ejecta deposits outside the crater rim, e.g., at the bosumtwi, ghana, and ries, germany, impact craters. the chesapeake bay crater is one of the largest impact craters that have been recently discovered. it is centered at 360 75’ to 37°61’ 30’’ n and 76° 42’ to 75030’ w, near the town of cape charles on virginia’s segment of the delmarva peninsula (fig.1). the crater is a complex peak ring structure buried about 300 to 500 m beneath the lower chesapeake bay, its surrounding peninsulas and the adjacent inner continental shelf (koeberl et al., 1996). the chesapeake bay impact crater was formed when a large comet or meteorite crashed in to shallow-shelf waters of the western atlantic ocean approximately 35 million years ago (powars et al., 2000; poag et al., 1994; poag et al., 2004). the impact structure has an age of about 35.5 million years, which places it in the late eocene, a time of an enhanced impact flux onto the earth (cf. koeberl and montanari, 2009; montanari and koeberl, 2000). the 85-km-wide crater includes the virginia coastal plain sediments, the southern part of the chesapeake bay, and a small part of the atlantic ocean (fig.2). it includes an inner basin surrounded by a ring of raised basement rock, as well as a flat-floored terrace zone that is bounded along the outer rim by a zone of concentric faulting. cross-sections of the crater were kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 130 constructed based on 10 multi-channel seismic reflection profiles transecting the bay and the 3 single-channel profiles on the inner continental shelf, as well as 56 boreholes drilled inside and outside the crater rim (poag et al., 1994). the seismic profiles define the outer rim structure of the crater (e.g., koeberl et al., 1996; poag et al., 2004). much of the shallow part of the crater is filled with a chaotic sedimentary deposit known as the exmore breccia. the exmore breccia contains angular clasts of older sedimentary material, and granite to metamorphic basement rocks in sandy matrix. a first petrographic and geochemical study of samples from the exmore breccia (imaged on seismic profiles in the environs of the central uplift with a maximum thickness of 1.2 km) showed that the breccia is composed of a range of clastic components (the various pre-impact sediments and crystalline granitoid basement) set in to fine-grained clasticmatrix of the same components. the first evidence for an impact crater came from the morphology and the occurrence of breccia (poag et al., 1994). final confirmation came from the identification in cores of partially melted basement rocks and multiple sets of planar deformation features in quartz and feldspar basement clasts (koeberl et al., 1996). the relatively recent discovery of the crater (powars et al., 1993; poag et al., 2004) has contributed to a better understanding of the geological framework of the middle and outer virginia coastal plain. moreover, the existence and location of the crater helps to explain the structure, stratigraphy and ground-water quality in the area. the chesapeake bay impact structure is also the source crater for the north american tektites – glassy distal ejecta that are found in a geographically extended strewn field along the eastern and central part of the north american continent (e.g., koeberl et al., 1996; deutsch and koeberl, 2006). recently, the chesapeake bay impact structure was the subject of a large international and interdisciplinary deep drilling project; the goal was to obtain a deep, continuously cored hole into the central part of the structure. drilling funds were provided by the international continental scientific drilling program (icdp), the u.s. geological survey (usgs), and the nasa science mission directorate. field operations were conducted at eyreville farm, northampton county, va., a few kilometers from cape charles. drilling was performed during september-december 2005, resulting in two continuously cored, deep holes. the usgs and rutgers university cored a kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 131 shallow hole to 140 m in april-may 2006 to complete the recovered section from land surface to 1766 m depth. details are described by gohn et al. (2006, 2008, 2009). figure 1. location map of the chesapeake bay impact crater, showing the crater rim, solid dots are drill core locations [note: n, newport news; w, windmill point; e, exmore; o, eyreville and k, kiptopeke (from gregory gohn, 1996)]. as noted by gohn et al. (2008), the recovered section consists of 1322 m of crater materials and 444 m of overlying post-impact eocene to pleistocene sediments. the crater section consists, from base to top, of: basement-derived blocks of crystalline rocks (215 m); a section of suevite, impact melt rock, lithic breccia, and cataclasites (154 m); a thin interval of quartz sand and lithic blocks (26 m); a granite mega-block (275 m); and sediment blocks and boulders, polymict, sediment-clast-dominated sedimentary breccias, and a thin upper section of stratified sediments (652 m). the results from the deep drillcore supplement the information that has been obtained from the sampling of the shallow drillcores (including those described in the present manuscript). 2. general geology the geological cross section of the chesapeake bay impact crater and its circular features was derived from seismic surveys and detailed examination of sedimentary cores (fig. 2). the kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 132 chesapeake bay impact structure lies beneath the shallow waters of the chesapeake bay and a thin veneer of coastal plain sediment (powers and bruce, 1999; poag et al., 1994; poag et al., 2004). the structure includes an inner basin surrounded by a ring of raised basement rock, encircled by a flat-floored terrace zone and bounded by the outer rim by a zone of concentric faulting (powars and bruce, 1999; koeberl et al., 1996). the crater is overlain by up to 650 m of early cretaceous to late eocene sedimentary material and underlain by granodioritic basement rocks the pre-impact coastal plain rocks consisted of a seaward-thickening wedge of mainly lower cretaceous to upper eocene age, poorly lithified, and mainly silicic-clastic sedimentary rocks (fig. 2). information from borehole samples indicates that the structure of the chesapeake bay crater is partially filled with the so-called exmore breccia, which is mainly composed of autochthonous sedimentary material and granitic to metamorphic, with minor basement rock clasts in a sandy matrix (e.g., poag et al., 1994; koeberl et al., 1996). after the formation of the crater, younger marine and non-marine sediments deposited on the coastal plain completely buried the structure. the crystalline basement (interior structure) of the chesapeake bay crater is expressed in the structure and thickness of the overlying breccia and of the post-impact sedimentary section. in particular, both the breccia and the post-impact section are notably thinner and structurally raised where they cross the peak ring and central peak (fig. 2). during the impact process, the impactor penetrated through the water column, the full thickness of the existing coastal plain sediments, slammed in to the basement rock, and vaporized, creating a catastrophic explosion and ejected material into the atmosphere (e.g., poag et al., 2004; powars and bruce, 1999). the basement rocks lining the crater cavity were melted, and the basement rocks in the region beneath and around the crater were faulted and fractured. the impact produced an inverted sombrero-shaped 85-km-wide complex crater that was immediately filled with sediments and rim collapse material and eventually buried by younger sedimentary deposits (powars and bruce, 1999). from geophysical and geological data, the chesapeake bay crater has been reported as one of the bestpreserved complex peak-ring structures documented on earth (poag et al., 1994, 2004). 3. methodology the samples for this study of shock metamorphism of the clastic sediments were collected by poag (2004) (us geological survey) from cores drilled earlier into the chesapeake bay crater. for the present study, 50 samples that are representative of the different lithological types kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 133 exhibited in the shallow drill cores were taken from various depths throughout the length of cores. petrographic thin sections were prepared from the samples and they were studied using a standard optical petrographic microscope. figure 2. schematic radial cross section showing half of “inverted sombrero” shape of the chesapeake bay impact crater, constructed from drill core and seismic data (from gohn et.al 2006). the location of the cross-section is indicated in fig. 1. the measurements of the planar deformation features (pdfs) were conducted using universal stage (e.g., emmons, 1943). more precisely, this method allows the determinations of the angle between the c-axis of a quartz grain and the poles of the planes of the planar deformation features. the data obtained from the universal stage measurements are then plotted with the aid of a stereographic equal-area net projection. after measuring the orientations of the pdfs in quartz grains, the data are arranged in table form to provide information about the axis of orientation and plane of orientation of each quartz grains in thin section. from the data, a histogram is plotted, with the x-axis representing the polar angle and the frequency on the yaxis. 4. results and discussion 4.1. petrographic observations kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 134 about 50 samples from four different drill cores were examined for their petrographic characteristics. table 1 lists the most characteristic products of shock metamorphism, as well as the associated diagnostic features. the best diagnostic indicators for shock metamorphism are features that can be studied easily by using the polarizing microscope. they include planar micro-deformation features; optical mosaicism; changes in refractive index; optical axis angle; isotropization and phase changes. these samples were taken from the following cores: exmore, windmill point, kiptopeke, and newport news; all of these have penetrated into the exmore breccia, but not into the deeper crater filling, which was recently intersected by the 2005/6 icdp-usgs project (gohn et al., 2006, 2008, 2009). about 50 of the samples which represent the exmore breccia in the interval between 1210.2 and 1388.2 feet (368.2 and 423.12 m), were taken from the exmore core. in addition 4 samples from the kiptopeke core between 1329.2 and 1332.25 feet (405.14 and 405.65 m) and 10 samples from windmill point core between 539.80 and 566.4 m depths were analyzed. the windmill point samples are dominated by sandy material with minor carbonate and crystalline basement lithologies. on the other hand, the three samples from newporte news core samples contained a comparatively higher amount of crystalline basement fragments and sediment materials. the kiptopeke section contains sediment and crystalline basement rocks, as well as a significant silt component, in addition to the sand and carbonate. the proportion of the shocked fragments as derived from the thin sections is relatively variable in each of the samples, where a limited number of shocked grains were identified from all the analyzed samples of this study. kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 135 figure 3. photomicrographs of thin sections showing typical fractures patterns resulting from low-pressure (∼8 gpa) shock metamorphism in clasts of crystalline basement from exmore breccia. (a) sample no. ex 1280.78 (390.4 m depth), shock fractures in feldspar, width of field 2.2 mm, plane polarized light. (b) sample no., ex 1290.d (393.4m depth); typical shock fractures in quartz with granitoid fragment or vein, plane polarized light; width of field 1.1 mm. (c) sample no., ex 1323.82 (403.5 m depth); granite fragment with annealed melt vein; width of field 3.4 mm; crossed polarizer. (d) sample no., ex 1341.4 (408.9 m); aphanitic impact melt with k-feldspar clasts; width of field 3.4 m, crossed polarizer. (e) and (f) sample no., k 1332.25 (406. 1 m depth), and nl 820.6 (250.12 m); quartz grains from matrix of exmore breccia (cross-polarized light), each showing two sets of pdfs, width of field ∼0.2 mm. k= kiptopeke corehole; nl= nasa langley core hole. kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 136 table 1. petrographic observations of individual clasts of samples from the thin section of the chesapeake bay impact crater. sample no. description ex1235.43 -.67 shock fracturing and incipient melting of quartz along fractures. particulate sample; glauconite in carbonate matrix, shale, shocked quartz fragments contain single set of pdf and silt derived fragments with shocked quartz 1235.43 -.67 feet (376.56 to 376.65 m). ex1237 particulate clay, silt, and centimeter sized k-feldspar with some quartz clasts. both k-feldspar and quartz contains up to two sets of pdfs 1237 feet (377.04 m ) depth. ex1290.6076 particulate sample: a breccia particle containing shocked quartz, unshocked granite, and granite derived fragments , pegmatite-or vein quartz, clay and sand. the shocked minerals in the lithic fragments are derived from crystalline basement lithologies. no shocked sediment particles were observed, except some rare shocked quartz grains in carbonate. some of the carbonate veins are cutting across the granite 1290.6076 feet (393.37 to 393.42 m) depth. ex1320 clay and quartzite fragments mostly unshocked, brecciated. one quartzite fragment has shock fractures 1320 feet (402.34) depth. ex-1329.20.40 carbonate, chert, granite with fractured quartz. shocked granite with plenty sets of pdfs; & unshocked granite fragments 1329.20-.40 ft (405.14 to 405.20 m) depth. ex1341.5 .67 unshocked microcline, partially altered impact melt, silt, & shocked quartzite and sand. myrmekite has developed from melting of feldspar 1341.5 .67 ft (408.89 to 408.94 m) depth. ex 1356.8 shocked quartz in a granitoid fragments, showing multiple sets of pdfs 1356.8 feet (413.55 m) depth. ex-1240.85-1241.0 granite fragments, silt microcline and shocked granite fragments with shock fractures and 1-set of pdf. reddish type breccia with annealed quartz clasts and shocked granite-derived clasts (quartz feldspar with shock fracturing and one set of pdf, 1240.85 -1241.0 feet (378.21 to 378.26 m) depth. ex1210.2 silt with abundant fine grained quartz, calcite, magnetite and biotite. feldspar and muscovite are less abundant. the matrix consists of calcite. no shock deformation noted 1210.2 feet (368.87 m) depth. ex 1286.7 clasts, medium to sub angular grain and lithic clasts, often showing minerals with reduced birefringence. most of the micas are kink banded. enhanced cleavage in some feldspar grains: no pdfs or other shock features 1286.7 ft (392.19m) depth. ex1337.6 quartz, microcline and plagioclase are the abundant clast phase. they are mostly medium to coarse grained. poorly sorted, with rounded to angular fragments. fragments are set into a fine-grained matrix of similar mineralogical composition, but with calcite as most abundant mineral. in places, magnetite alteration has caused fe-oxide staining on the matrix. no shock deformation features 1337.6 feet (407.7 m) depth. ex1331.0 dominated by quartz, microcline and some plagioclase fragments, mudstone, siltstone and carbonate clasts. over 90% granite derived material and 10 % vol sediment; no shock effects 1331.0 feet (405.69 m) depth. nn433.8 fractured and brecciated granite, fine grained melts rock that could represent impact melt rock and unshocked granite clasts and fine grained melt rock with angular and well rounded quart clasts in an altered matrix 433.8feet (132.22 m) depth. wp552.11 medium grained sand with fine grained carbonate clasts. some folded, mica clasts, unshocked 552.11 m (168.28 m) depth. ex= exmore; nn= newport news; wp= windmill point. kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 137 table 2: preliminary composite geologic section for the eyreville boreholes (from gohn et al., 2006; reimold, et al., 2006). 0 to 444 m post-impact sediments 444 to 1,096 m sediment-clast breccia and sediment megablocks 1,096 to 1,371 m granitic megablock(s) 1,371 to 1,393 m lithic blocks in sediment 1,393 to 1,550 m suevitic and lithic breccia 1,550 to 1,766 m schist and pegmatite; breccia veins the overwhelming number of shocked grains is derived from basement granitoids. only rarely it was possible to observe weak to moderate shock deformation in sediment-derived particles. granitoids are widely present, even though the clastic sedimentary components are important throughout the drilled breccia sequences, carbonates are relatively rare. on the other hand, mafic components are also extremely rare (poag et al., 2004). most thin sections contained 10 to 15 mineral fragments, but fine grained material (<1 mm grain size) may have contained several grains. exmore samples do frequently contain very small proportions of shock particles, but here too, very weak and weak shock degrees are dominant. table 3. thin-section samples and numbers with those that have only shocked quartz grains from the chesapeake bay crater, usa. no. sample number number of grains 1 ex 1235.43-.67 3 2 ex1237 3 3 ex 1280.78 3 4 ex 1290.60-.76 2 5 ex 1312.0-.14 3 6 ex 1329.20-.40 3 7 ex 1341.5-.67 4 8 ex 1356.8 1 total 22 overall, the exmore breccia is dominated by particulates of silt, shocked and unshocked granitic fragments, shale, clay with very rare shocked quartz grains, fractured and locally melted granite, unshocked microcline, sandstone and opaque mineral fragments. to generalize, the shocked grains identified in the exmore breccia are far less than 2 % of all grains studied. with regard to kiptopeke samples, none of them exhibited any shock deformation. windmill point samples showed rare fragments with a wide variety of different shock effects, including shock fracturing kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 138 only or impact melt breccia. in newport news samples, several fragments and impact melt with evidence of shock metamorphism were noted. 4.2. planar deformation feature (pdf) measurements confirmation of an impact origin requires conclusive evidence that the rocks and minerals have undergone shock metamorphism, which is defined by high pressures and temperatures (up to 100 gpa and 1000 0c), and strain rates associated with impact cratering (from 5 gpa to > 50 gpa). the type of metamorphism depends on the shock pressure experienced. planar deformation features (pdfs) is the designation currently used for distinctive and shock produced microstructures that were formerly given a variety of names (e.g. “planar features”, “shock lamella”). in contrast to planar features, with which they may occur, pdfs are not open cracks. instead they are sets of closed, extremely narrow , parallel planar regions (fig. 3e, f). most of the information from impact structures comes from dense, coherent quartz bearing crystalline rocks (french, 1998). there is a relatively little information about the effects of shock deformation in other kinds of quartz-bearing rocks, e.g. porous sandstone or fine grained shale. several studies have demonstrated that shocked sandstones and shale’s also develop pdf in quartz, and even diapeletic quartz and feldspar glasses, similar to those observed in other craters in shocked crystalline rocks (fig.3). despite these similarities a growing amount of data now indicate that sedimentary rocks respond differently to shock pressure than do crystalline rocks (greive et. al., 1996). the more important difference between the sedimentary porous rocks and crystalline rocks is that a shock wave passing through sediments will generate more heat than in passing through crystalline rocks. extremely narrow , parallel planar regions (fig. 3e, f). evidence of shock metamorphism is abundant in rocks and mineral clasts from the exmore breccia in the chesapeake bay impact structure was described earlier by koeberl et al. (1996) and poag et al. (2004). a first petrographic study from the exmore breccia showed that the breccia is composed of a range of clastic components, such as various pre-impact sediments and crystalline granitoid basement set in to fine-grained clastic matrix of the same components. more than 50 specimens from four boreholes (exmore, windmill point, kiptopeke, and newporte news) into the shallow outer annulus of the chesapeake bay crater were examined for the presence of distinctive mineral deformation features. most of the samples analyzed did not show any significant deformation features at all. a specimen from windmill point and newport news kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 139 revealed only micro-deformation features limited to the development of rather wide-spaced fractures and in some parts shows undulatory extinction (table 1). besides, the chesapeake bay impact structure deep drilling project (cbis project) was completed its coring operations during september–december 2005 and april–may 2006. cores were collected continuously to a total depth of 1766 m. the recovered section consists of 1322 m of impactites beneath444 m of post-impact continental shelf sediments (table 2). out of 50 thin sections analyzed only 8 shows pdf characteristics in the exmore breccia samples from depths of 1210.2 to 1388.2 feet (table 3). these samples are mainly shocked granite fragments with quartz and rarely shocked quartz grains in a carbonate matrix. some shocked alkali feldspars were also observed, which showed up to two sets of pdfs (fig.3). because shocked-produced pdfs in a given quartz grain are parallel to only few specific crystallographic planes, the angles measured between the quartz c-axis and the poles to to the pdf tends to concentrate at a few specific values (french, 1998). in a histogram plot, the poles appear as sharp concentrations at specific angles, and each of which belongs to a particular plan. this sharply peaked pattern of pdf orientations, typically characterized by peaks at c (0001) (00), � (101 3) (230), and π (101 2) (320) is one of the most useful and used for indicating characteristics of shock metamorphism (fig.4). figure 4. histogram showing orientations of pdfs in quartz from chesapeake bay crater (from exmore breccia). in the diagram, the angle between the quartz c-axis and the pole to the planar features is plotted on the x-axis; on the y-axis the frequency is given for each angle. kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 140 shock metamorphism in these samples is manifested by a number of quartz grains with single occasionally with multiple sets of planar deformation features (table 4). the overall percentage of pdf-bearing quartz grains in the investigated core samples is far less than 1 vol%. the results include data for 2 grains with 1 sets of pdfs, 17 grains with two sets each and 3 grains with three sets (table 3) each, and also the data showings the frequency of the angles between the quartz c-axes and the poles to the planes of pdfs in degrees. figure 4 shows a histogram with orientations of the poles to the planes of pdfs relative to the c-axis of the quartz grains. the orientation of 45 sets of pdfs was determined in 22 quartz grains from the exmore breccia. approximately 35 % of the sets conform with ω{101 3} and 10 % to π{101 2} orientations. most of the remaining sets are oriented parallel to r {101 1} and {2131}, and basal the plane is absent. seventeen grains with 2 sets could be reliably indexed at shock diagnostic orientations. most abundantly observed pdfs in the exmore breccia in the quartz grains are one to two sets of planes, which are indicative of moderate degrees of shock. mainly {101 3} and {101 2} are the dominant orientation, which provide conclusive evidence that the rocks and minerals have undergone shock metamorphism; that is, subjected pressures of 10-25) (fig 4). table 4. number of quartz grains with a number of sets of pdf planes and orientations from the chesapeake bay impact structure, usa. set of planes orientations number of grains 1 set 11 2 1, (0001101 3) 2 2 sets 51 6 1, 101 2 1 (0001101 3), 101 1 1 1122, 2131 1 101 3, 101 3 2 2131, 2131 1 101 3, (101 211 2 2) 4 101 3, 101 1 2 11 2 1, 22 4 1 1 (0001-101 3) 1 101 3, 101 2 1 101 3, 11 2 2 1 101 3, 11 2 1 1 3 sets 2131, 101 2, 101 3 (0001101 3), (0001101 3), 101 1 101 1, 11 2 2, 101 3 kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 141 note: (0001-101 3) means between 0 to 23° and (101 211 2 2), 28° to 48°. from 22 grains, 14 grains were indexed, i.e., 63.6%. shock metamorphism is not a thermodynamically reversible process and most of the structural and phase changes in mineral structures associated with impact are uniquely characteristic of the high pressures (5 to >50 gpa) with extreme strain rates (106 to 108 s-1) (koeberl, 1997). these conditions are in sharp contrast to the conditions for endogenic metamorphism of crustal rocks, with maximum temperature of 1,200 0c and pressures of usually <2 gpa (fig. 5). figure 5. comparison of pressure-temperature fields of endogenic metamorphism and shock metamorphism. besides, onset pressures of various irreversible structural changes in the rocks due to shock metamorphism are indicated. the curve on the right side of the diagram shows the relationship between pressures and post-shock temperature for shock metamorphism of granitic rocks. (from grieve, 1987, montanari and koeberl, 2000). 5. conclusions the chesapeake impact structure is a large complex crater of late eocene age and 85 km diameter, which is hidden beneath the shallow waters of the coastal plain sediments. it is the largest impact crater currently known in the usa. for petrographic analysis of the exmore kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 142 breccia, samples were mainly collected from drill cores from the exmore core and from three other shallow cores. the exmore breccia contains angular clasts of older sedimentary material and minor granitic to metamorphic basement rocks. shock clasts are very rare and most of the shock effects include shock fracturing in quartz, pdfs in both quartz and feldspar, and rare impact melt and glass fragments. shock effects were recognized only in crystalline rock fragments or clasts, but not in sedimentary material. evidence for shock metamorphism comes from exmore breccia samples from depths of 1210.2 to 1388.2 feet (368.2 and 423.12 m). the results showed a very small component of shocked material, in the form of shock-deformed quartz, and to an even lesser degree feldspar, and somewhat less abundant altered melt particles, throughout the section. the proper pdfs was found in only 8 samples of exmore breccia, which were then analyzed for the orientations of the pdfs in quartz grains by a universal stage. in quartz and feldspar, up to three sets of pdfs with shock-characteristic crystallographic orientations were found. the pdfs in shocked quartz were found to occur in intersecting sets of planes corresponding to specific crystallographic orientations with {1013}, {1012}, {1011}, and {2131}. most abundantly observed shock fractures are shock fracturing indicative of shock pressures <15 gpa and 1-2 sets of pdfs in quartz, which is indicative of moderate degree of shock. however, between 408.89 to 408.94 m depths granite fragment with annealed melt vein and myrmekite has developed from melting of feldspar. 6. acknowledgement this work was supported by the austrian academic exchange service (oad) to the author is gratefully acknowledged. the laboratory facility and the support provided by prof. c. koeberl apart from going through the manuscript and giving useful comments is highly appreciated. the author also appreciates the hospitality of the university of vienna, austria, and the support and co-operation during analysis of samples and reviewing of the manuscript. the drilling at chesapeake bay was supported by the icdp and the core studies in vienna were supported by the austrian science foundation (grant p18862 to c. koeberl). kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 143 7. references deutsch, a & koeberl, c. 2006. establishing the link between the chesapeake bay impact structure and the north american tektite strewn field: the sr-nd isotopic evidence. meteoritics and planetary science, 41: 689-703. emmons, r.c. 1943. the universal stage (with five axes of rotation). geological society of america, memoir 8, 205 pp. engelhardt, w.v & bertsch, w. 1969. shock induced planar deformation structures in quartz from the ries crater, germany. contributions to mineralogy and petrology, 20: 203-223. french, b.m. 1998. traces of catastrophe: a handbook of shock metamorphic effects in terrestrial meteorite impact structures. lunar and planetary institute contribution, 954, 120pp. grieve, r.a.f. 1987. terrestrial impact structures. annual reviews of earth and planetary science, 15: 245-270. grieve, r.a.f. 1990. impact cratering on the earth. scientific american, 262 (4): 66-73. grieve, r.a.f. 1991. terrestrial impact: the record in the rocks. meteoritics, 26: 175-194. grieve, r.a.f & cintala, m.j. 1992. an analysis of differential impact-melt craters scaling and implications for the terrestrial impact record. meteoritics, 27: 526-538. gohn, g.s., koeberl, c., miller, k.g., reimold, w.u., cockell, c.s., horton, j.w. jr., sanford, w.e & voytek, m.a. 2006. chesapeake bay impact structure drilled. eos, transactions of the american geophysical union, 87: 349-355. gohn, g.s., koeberl c., miller, k.g., reimold, w.u., browning, j.v., cockell, c.s., horton, j.w., kenkmann, t., kulpecz, a.a., powars, d.s., sanford, w.e & voytek m.a. 2008. deep drilling into the chesapeake bay impact structure. science, 320: 1740-1745. gohn, g.s., koeberl, c., miller, k.g & reimold, w.u (eds.). 2009. deep drilling in the chesapeake bay impact structure: geological society of america special paper (in press). horton, j. w. jr., gohn, g. s., powars, d. s & edwards, l. e. 2007, origin and emplacement of impactites in the chesapeake bay impact structure. in: k. r. evans, j. w. horton, d. t. king and j.r. morrow (eds.), the sedimentary record of meteorite impacts, geological society of america special paper, 437:73-97. koeberl, c. 1998. identification of meteoritical components in impactites. in: m.m. grady, r. hutchison, g.j.h. mccall and d.a. rothery (eds.), meteorites: flux with time and impact effects. geological society of london, special publication, 140: 133-152. koeberl, c & montanari, a (eds.). 2009. the late eocene earth: hothouse, icehouse, and impacts. geological society of america, special paper no. 452. kassa, a (mejs) volume 2 (2):128-144, 2010 © cncs mekelle university 144 koeberl, c., poag, c.w., reimold, w.u & brandt, d. 1996. impact origin of the chesapeake bay structure and the source of the northern american tektites. science, 271 : 1263-1266. koeberl, c., reimold, w.u., brandt, d., dallmeyer, r.d & powell, r.a. 1997. target rocks and breccias from the ames impact structure, oklahoma: petrology, mineralogy, geochemistry, and age. in: k. johnson and j. campbell (eds.), the ames structure in northwest oklahoma and similar features, oklahoma geological survey, oklahoma, usa, circular 100:169-198. melosh, h.j. 1989. impact cratering: a geological process, oxford university press, new york, 245pp. montanari, a & koeberl, c. 2000. impact stratigraphy: the italian record. lecture notes in earth sciences, volume 93, springer verlag, heidelberg, 364pp. poag, c.w & foster, d.s. 2000. chesapeake bay impact crater. new seismic evidence of a central peak. lunar and planetary science 31, abstract no. 1358 (cd-rom) (abs). poag, c.w., powars, d.s & mixon, r.b. 1994. conclusive in atlantic coastal plain evolutioneffects of the chesapeake bay bolide impact. geological society of america, abstracts volume 26 (with programs), a-152 (abs). poag, c.w., hutchinson, d.r., colman, s.m & lee, m.w. 1999. seismic expression of the chesapeake bay impact crater: structural and morphologic refinements based on new seismic data. in: b.o. dressler and v.l. sharpton (eds.), large meteorite impacts and planetary evolution ii. geological society of america special paper 339:149-164. poag, w., koeberl, c & reimold, w.u. 2004. the chesapeake bay crater: geology and geophysics of late eocene submarine impact structure. springer-verlag, heidelberg, 522pp. powars, d.s. 2000. the effects of the chesapeake bay impact crater on the geologic frame work and the correlation of hydrogeologic units of southeastern virginia, south of the james river. u.s. geological survey professional paper, 1622: 47. powars, d.s & bruce, t.s. 1999. the effects of the chesapeake bay impact crater on the geological framework and the correlation of the hydrogeologic units of the lower york-james peninsula, virginia. us geological survey professional paper, 1612: 1-82. powars, d.s., poag, w.c & mixon, r.b. 1993. the chesapeake bay “impact crater” –stratigraphic and seismic evidence. geological society of america, metamorphism of natural materials abstracts volume, mono book corporation, baltimore, 243-253 (abs). short, n.m. 1970. progressive shock metamorphism of quartzite ejecta from the sedan nuclear explosion crater. journal of geology, 78: 705-732. taylor, s.r. 1992. solar system evolution. cambridge university press, cambridge, 307 pp. microsoft word 1. cover pages kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 compositional differences between felsic volcanic rocks from the margin and center of the northern main ethiopian rift *kurkura kabeto1, 2, yoshihiro sawada2, barry roser2 1 department of earth science, college natural and computitional sciences, mekelle university, p.o.box 231, mekelle, ethiopia. (*kurkura57@yahoo.com/ kurkura.kabeto@mu.edu.et) 2 department of geosciences, shimane university, matsue 690-8504, japan abstract pliocene felsic rift margin and quaternary rift center volcanic rocks from the northern main ethiopian rift (mer) exhibit contrasts in major and trace element contents and sr-nd isotopic ratios. quaternary rift center felsic volcanic rocks are mainly peralkaline trachytes and rhyolites, whereas pliocene felsic rift margin volcanic rocks are represented by benmoreites, weakly peralkaline trachytes and rare rhyolites. most of the felsic rift margin volcanic rocks have greater al2o3, k2o, nb, zr, rb, and sr, and lesser cao, zr/nb, and cao/al2o3 than rift center volcanic rocks. these contrasts may have been inherited from differences in the compositions of their parental basic magmas, which were produced by variable degrees of partial melting. in both series, the felsic volcanic rocks generally have higher initial srisotopic (0.7038-0.7073) ratios than their basic equivalents (0.7035-0.7046). ndisotopic ratios of most felsic rift center samples (0.5129-0.5126) are similar to their associated basic volcanic rocks. in contrast, the ndisotopic ratios (0.5128-0.5124) of felsic rift margin volcanic rocks are commonly lower than their companion basic volcanic rocks (0.512806-0.512893), and are relatively lower than rift center equivalents. the elemental and sr-nd isotopic compositions of the volcanic rocks suggest that fractional crystallization from differing basic parents accompanied by a limited assimilation (afc) was the dominant process controlling the genesis of the mer felsic volcanic rocks. keywords: ethiopia; northern main ethiopian rift; bimodal volcanism; parental difference; sr-nd isotopes, fractional crystallisation 1. introduction the main ethiopian rift (mer), the southwestern ethiopian rift zone (swerz), the tana rift and the afar region represent the northernmost part of the east african rift system (fig. 1). the ethiopian volcanic province is dominated by up to 300,000 km3 of generally fissure-fed midtertiary basic (sio2 < 53 wt.%) volcanic rocks, and minor associated felsic (sio2 > 53 wt.%) products. however, the proportion of felsic products in the ethiopian rift valley itself is high, reaching about 90% of the total volume (mohr, 1992). mekelle university issn: 2073-073x 4 mailto:kurkura.kabeto@mu.edu.et kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 between 45 and 22 ma, volcanic activity in the ethiopian plateau (figs. 1a and b) was characterized by fissural flows. central volcanoes covered the fissural flows beginning at about 30 ma and 15-13 ma, and erupted intermittently into the pleistocene (morton et al., 1979; woldegabreil et al., 1990; wolde, 1996; stewart and rogers, 1996; chernet et al., 1998; pik et al., 1998; ayalew et al., 2002). recent geochemical and isotopic studies have focused on the oligocene-miocene to quaternary basic-felsic volcanism that accompanied the formation of the mer. these studies have proposed the involvement of distinct mantle components in various proportions, and the importance of the afar mantle plume and lithospheric mantle in the sources of the basic lavas (fig. 1). figure 1. maps showing the location of the study area. a) index map showing surface expression of the ethiopian rift system and volcanic cover (wolde, 1996) and the ethiopian plateau (ep, stewart and rogers, 1996). b) volcanic and tectonic structures of the mer. the white ellipses are the study areas. n (northern), c (central), and s (southern) sectors of the mer; swerz is the southwestern ethiopian rift zone. c) sample sites, felsic volcanic centers and volcanic and tectonic structures of the addis-nazreth region. ytvl yerer tulu welel volcano tectonic lineament from abebe et al. 1998. although the previous studies have provided a well-documented framework for the genesis of the basic magmas in mer, the associated felsic magmas are not well studied. recently, several geochemical and isotopic studies of felsic products have been carried out in the rift center at debre zeit, gedemsa, and asela-ziway mekelle university issn: 2073-073x 5 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (fig. 1) (gasparon et al., 1993; peccerillo et al., 1995; trua et al., 1999; abebe et al., 1998; boccaletti et al., 1999), on volcanic rocks which are mostly younger than 2 ma. the felsic volcanic products at the rift margin (addis ababa) and rift center (nazreth) regions and their compositional variations are not yet well studied. this paper presents new elemental and sr-nd isotope data for selected volcanic sequences from the northern sector of the mer (fig. 1). based on the petrographic, geochemical, and isotopic characteristics of the volcanic units, we describe the compositional differences between the volcanic rocks at the rift margin and rift center, and discuss the petrogenetic relationships between basic and felsic magmas in order to assess the influence of basic parents and continental crust in the genesis of the felsic melts. 2. geological summary of the addis ababa and nazreth regions the study area is located in the center of the ethiopian dome (fig 1), and contains volcanic sequences that are directly related to the northern main ethiopian rift (mer) activity. reevaluation of seismic refraction data for the region by makris and ginzburg (1987) revealed thinning of the crust from 44 km thick at addis ababa to 30-26 km in the center of the mer to the east. this led wolde (1996) to regard the volcanic sequences at debre zeit and to its east as rift center, and miocene to pliocene volcanic rocks in the addis ababa region, west of debre zeit as rift margin. on the basis of whole-rock and mineral k-ar and 40ar-39ar ages, morton et al. (1979) and chernet et al. (1998) found that the volcanic cover extending from addis ababa to nazreth showed age progression from 22.8 ma in plateau basalts to 0.21 ma in the rift center volcanic rocks. at the base of the rift margin volcanic rocks, alkaline-transitional basalt (22.8 ma) of the plateau unit is in fault contact with the overlying intoto unit (22.2-22 ma) (morton et al. 1979; chernet et al. 1998). the intoto unit consists of trachyte-rhyolite flows and associated ignimbrites at its base (22.2 ma) and plagioclase phyric basalt (22 ma) in its upper part. the early miocene plateau and intoto units represent bimodal volcanic rocks, which were formed during a localized terminal episode following the massive oligocene fissural basalt activity of the northwestern ethiopian plateau and are present at the rift margin in the addis ababa region (morton et al., 1979; begazi et al., 1993; chernet et al., 1998). because of their close realationship, the plateau and intoto units are here collectively referred to as the plateau unit mekelle university issn: 2073-073x 6 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (22.8-22 ma). the geochemical data for the plateau unit is not discussed in this paper because they are pre-rifting eruptions. volcanic activity resumed at the rift margin after a considerable hiatus between 22-10 ma, by eruption of transitional-alkaline basalts of the addis ababa unit (9-7 ma). this was followed by the welded trachytic tuffs (5.1 and 3.3 ma) of the nazreth unit, which are thought to have been derived from the mostly trachytic pliocene (4.6-3.09 ma) wechecha, menagesha, furi, and yerer volcanoes (fig. 1). these centers are collectively designated as the wechecha unit (chernet et al., 1998). predominantly felsic volcanic products were erupted in the debre zeit and nazreth regions in the rift center between 2.0-0.20 ma. this sequence consists of the nazreth, keleta, boku-tede, bofa, dera-sodere, gedemsa, boseti, and melkasa units in ascending order (fig. 1; boccaletti et al., 1999). for simplicity, the felsic volcanic rocks of nazreth, keleta, boku-tede, and derasodere units are here grouped as the nazreth unit, whereas the basaltic rocks of the bofa and melkasa units are collectively termed the rift center basic volcanic rocks. 3. classification and petrographic summary most of the samples investigated here were fresh, and collected from lava flows, except for a few welded ignimbrites from the rift center (table 1). according to the tas classification diagram (le bas et al., 1986) the rock types in both areas range from basalt to rhyolite, but trachytes and rhyolites predominate (fig. 2). the rocks fall in numerous compositional fields, making terminology cumbersome. therefore, a restricted set of terms has been adopted here. rock samples with sio2 < 53 wt.% are defined as basic, whereas samples with sio2 > 53 wt.% are classed as felsic. in common with many bimodal suites in continental rifts and oceanic islands, the basic rocks at the rift margin are generally alkaline or transitional, whereas rift center equivalents are typically transitional (wolde, 1996) (fig. 2). strongly felsic alkaline rocks at the rift margin and center are weakly peralkaline and strongly peralkaline, respectively (table 1). according to macdonald (1974), most of the peralkaline felsic volcanic rocks are commendites with rare pantellerites. however, most of the gedemsa unit samples are pantelleritic (peccerillo et al., 1995) (not shown in figure). mekelle university issn: 2073-073x 7 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 petrographically, the basic rocks in both rift margin and center are usually aphyric. porphyritic samples on the other hand are rare and contain about 15-25% phenocrysts. the phenocryst minerals are olivine, clinopyroxene, and plagioclase with or without opaques. the groundmass of the basic lavas consists of the above phenocryst phases and accessory glass, zircon, apatite, and titanite, along with secondary alteration products including sericite/carbonate, iddingsite, and hematite. loss on ignition values in these samples differ little from the unaltered samples (table 1). figure 2. classification of volcanic rocks of the northern mer according to the scheme of le bas et al. (1986). the alkaline-sub-alkaline boundary is from irvine and baragar (1971). additional data for the volcanic rocks from abebe et al. 1998), chernet (1995) and peccerillo et al. (1995). the felsic volcanic rocks in the rift margin are relatively aphyric compared to the basic rocks, and generally show trachytic textures. the phenocryst minerals (<15%) are commonly plagioclase (albiteoligoclase) and anorthoclase, and lesser sanidine, nepheline, alkali amphibole (rebeckite), and aegirine-augite (chernet, 1995; abebe et al., 1998). plagioclase and anorthoclase are the common phenocryst minerals in the rift margin felsic volcanic rocks. groundmass contains plagioclase, k-feldspars, opaques, augite, and aegirine-augite. some feldspar grains show melt inclusions along their margins, and rarely amphiboles are altered. the felsic rift center volcanic rocks contain similar type of minerals as their rift margin equivalents. majority of the samples are aphyric, but few samples containing up to 35% phenocryst phases with both felsic and ferromagnesian minerals forming the phenocryst and groundmass phases. felsic minerals are usually sanidine, quartz, sodic plagioclase, and anorthoclase, whereas the ferromagnesian minerals are aegirine-augite, sodic-amphibole, olivine, mekelle university issn: 2073-073x 8 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 and opaques. both the lavas and ignimbrites contain the same minerals, but differ in their textures. the lavas commonly show perlitic cracks/spherulitic groundmass textures, whereas ignimbrites show eutaxitic textures with dominantly vitrophyric fiamme groundmasses. 4. geochemistry 4.1. analytical procedures out of 125 collected samples, 75 selected samples from each unit were analyzed for major and trace elements and sr-nd isotopes (table 1) in the department of geoscience, shimane university, japan. samples were crushed in a tungsten carbide ring mill (roser et al., 1998), and dried at 1100c for 24 hours. no significant nb or ta contamination was present in the carbide ring mill compared to that ground in agate (roser et al., 1998). the remaining xrf data will be provided upon request. major and trace element analyses were performed using glass beads prepared either by fusing 0.7g of rock powder mixed with 3.5g of li2bb4o7 (norrish and hutton, 1969) or by mixing 1.8g sample with 3.6g alkali flux (libo2:lib4o7 = 1:4) (kimura and yamada, 1996). analyses were made using a rigaku rix 2000 x-ray fluorescence spectrometer, using conventional peak/background methods, with calibration against a suite of geological survey of japan (gsj) and usgs rock standards. the reproducibility was monitored with appropriate international standards jb01, jb02, and jb03, and was within +10% for all elements with concentrations higher than 10 ppm. srand ndisotopic measurements and analyses of sm and nd (by isotope dilution) were carried out using finnigan mat262 thermal ionization mass spectrometer, following the methods of iizumi et al. (1994, 1995). measured 87sr/86sr and 143nd/144nd ratios were normalized to 87sr/88sr = 0.1194 and 146nd/144nd = 0.7219. during the analysis of unknowns, measurements of 87sr/86sr and 143nd/144nd in nbs 987 and jmc standard samples were 0.71026 ± 18 (2σ, n = 10) and 0.51196 ± 10 (2σ, n = 10), respectively (table.1) 4.2. major element data whole rock analyses and sr-nd isotope data of representative samples are listed in table 1. the remaining data are available upon request. the basic (sio2 < 53 wt.) rocks have mgo contents between 4 and 14 wt.%, mg-numbers (mg#) between 50 and 74, ni ≤ 380 ppm and cr ≤ 822 ppm. most of these values suggest that very few rocks represent the primary mantle melts (sato, mekelle university issn: 2073-073x 9 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 1977; wilson, 1989). majority of the samples having mg# between 44 and 50 suggest that they do not represent primary magma compositions (table.1). figure 3. plots of selected major elements (wt.%) against differentiation index (sio2) for northern mer volcanic rocks. symbols as in fig. 2. selected major and trace elements plotted against sio2 are shown in figs. 3, 4 and 5. with the exception of two intermediate samples, all the felsic rocks have sio2 > 57 wt.%, and an apparent sio2 gap (53-57 wt.%) exists between the basic and felsic volcanic rocks. in all volcanic sequences mgo, ∑feo and cao generally decrease with increasing sio2 and k2o (fig. 3). however, na2o contents increase from about 2 wt.% in the basic volcanic rocks to about 7 wt.% in the felsic rocks (at 65 wt.% sio2), and felsic samples. in the boseti unit, however, na 0 5 10 15 20 0 1 2 tio2 0 3 6 9 12 feotot 655545 0 3 6 9 12 cao 15 0 5 10 mgo 0.0 1.0 p2o5 0 2 4 6 8 na2o 75655545 0 2 4 k2o sio2sio2 75 0.5 1.5 al2o3 w t.% o xi de then decreases to 4.2 wt.% increasing sio2 (>70%) in most of the 2o continues to increase in some of the felsic rocks. al2o3 contents in basic samples range from 13.0 to 21.3 wt.%, maintain similar values (13.3-17.5 wt.%) in felsic samples through to 65 wt.% sio2, and then decrease to values as low as 9.2 wt.% at 75 wt.% mekelle university issn: 2073-073x 10 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 sio2. p2o5 and tio2 contents also tend to increase from basic to intermediate compositions (up to 55 wt.% sio2), and then sharply decrease up to 65 wt.% sio2 and remain flat (fig. 3). figure 4. plots of selected trace elements (ppm) against differentiation index (sio2 wt.%) for northern mer volcanic rocks. the lines on the zr, nb, sr and rb versus sio2 illustrate the compositional contrasts between the volcanic rocks in the rift center and margins. the shaded area on the zr and nb plots indicate where samples from the furi and yerer mountains overlap samples from the rift center. symbols as in fig. 2. mekelle university issn: 2073-073x 11 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 compositional differences exist between the rift margin and rift center volcanic rocks (table 1; fig. 3). for example, cao contents in the rift center basic rocks (9.4-11.3 wt.%) are generally higher than most of the rift margin equivalents (7.7-10 wt.%), except in few clinopyroxenephyric samples from the addis ababa unit that are younger (10.9-12.5 wt.%). in contrast, al2o3 contents of most rift margin basic volcanic rocks are higher (14.8-18.6 wt.%) compared to the rift center equivalents (13-17.5 wt.%). the contrasts in cao and al2o3 seen in the basic lavas of the two regions are also apparent in the felsic volcanic rocks. al2o3 contents are greater in most of the felsic rift margin volcanic rocks than in the rift center, whereas cao contents are generally greater in the rift center (fig. 3). k2o concentrations are generally greater and ∑feo contents lesser in the rift margin felsic volcanic rocks than in the rift center. however, the above compositional differences become less pronounced in samples with sio2 contents > 67 wt.%. rift center felsic samples are generally richer in sio2 than most from the wechecha (pliocene) unit at the rift margin (fig. 3) 4.3. trace element data in both the rift margin and rift center volcanic sequences, compatible elements such as ni, co, and cr decrease in abundance with increasing sio2 (table 1). this indicates the influence of olivine, clinopyroxene, and fe-ti oxide fractionation. zr, nb, y, and rb, being incompatible elements show increase in their concentration with fractionation within each rock series, albeit with some scatter (fig. 4). sr and ba contents in the felsic volcanic rocks generally decrease with fractionation, representing compatible behavior, though they too show wide variations. most rift margin basic lavas have greater zr and nb contents than do the rift center basic lavas. moreover, at given sio2 content sr is much more enriched in rift margin basic lavas than in their rift center equivalents (fig. 4, table 1). zr, nb, sr, and rb are also generally more enriched in their rift margin felsic rocks than in quaternary rift center felsic equivalents. however, y and ba abundances mostly overlap, as does sr at > 65 wt.% sio2. among the wechecha felsic samples, high zr and nb are observed in the menagesha and wechecha mountain samples (table 1), whereas relatively low nb and zr contents characterise samples from the furi and yerer mountains (fig. 4). 4.4. ndand srisotope data twenty-eight samples spanning the compositional range from the least fractionated mgo-rich rocks to the most fractionated rhyolite samples were analysed for srand ndisotopes. isotopic mekelle university issn: 2073-073x 12 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 ratios as shown in table 1 are plotted in figure 5, together with data for 15 samples from chernet (1995) and abebe et al. (1995). initial 143nd/144nd ratios in the basic lavas range from 0.512812 to 0.51289, and from 0.51237 to 0.51286 in the felsic volcanic rocks. initial 87sr/86sr ratios range from 0.70349 to 0.70456 in the basic lavas, and from 0.70446 to 0.70783 in the felsic volcanic rocks. the rift margin basic volcanic rocks have higher ndand lower srisotopic ratios than rift center equivalents (table 1; fig. 5). in contrast, felsic volcanic rocks from the rift margin have lower ndisotopic ratios than most of their rift center equivalents. however, their srisotopic compositions are equally variable. the felsic volcanic rocks extend from the isotopic range of the basic volcanic rocks towards higher 87sr/86sr (fig. 5). most of the felsic rift center volcanic rocks lie above the debre zeit field (gasparon et al. 1993), whereas the felsic rift margin volcanic rocks partly overlie it. rift center felsic volcanic rocks overlie the field defined by equally felsic lavas from northern kenya (kabeto et al., 2001) (fig.5). figure 5. initial 87sr/86sr and 143nd/144nd ratios for volcanic rocks of the study area, compared to west central (wc) afar and mer (hart et al., 1989), debre zeit (gasparon et al., 1993), south ethiopian (stewart and rogers, 1996), asela-ziway & chilalo (trua et al., 1999), northern kenyan volcanic rocks (kabeto et al., 2001b), and the east african carbonatite line (eacl). measured 143nd/144nd ratio is used for some samples (table 1). symbols as in fig. 2. 5. discussion it is well established that compositional differences in parental basaltic magmas are reflected in the compositions of felsic melts (wilson et al., 1995; panter et al., 1997). fractional crystallization of basaltic magmas with some crustal assimilation and partial melting of basic mekelle university issn: 2073-073x 13 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 lower crust/underplated igneous rocks were proposed as dominant processes for generation of felsic melts in the mer rift center (fig. 1; gasparon et al., 1993; abebe et al., 1998; peccerillo et al., 1995; trua et al., 1999; boccaletti et al., 1999). the influence of different parental magma compositions and the processes involved in the genesis of felsic melts in the northern sector of the mer are discussed below. 5.1. influence of parental magma compositions the general, elemental contrasts between the rift margin and rift center volcanic rocks discussed above (figs. 3 and 4; table 1) are clearly evident on cao/al2o3 vs sio2, zr vs nb, and zr/nb vs zr plots (fig. 6). at a given sio2 content most of the basic rocks (sio2 < 53 wt.%) from the rift center are displaced towards higher cao/al2o3 ratios (fig. 6a). few basic rocks from the rift margin have cao/al2o3 ratios comparable with rift center equivalents, and in both groups the ratio decreases with fractionation. cao/al2o3 ratios remain higher in the felsic rift center rocks (sio2 > 53 wt.%) than in rift margin equivalents, but a few felsic samples from the wachecha (furi and yerer mts.) unit overlap (table 1). this may be due to similar fractionating phases controlling their evolution, or indicate that they were derived from compositionally similar basic parents. zr and nb contents show a well defined linear correlation (fig. 6b), and both being incompatible elements increase with fractionation (kamber and collerson, 2000; kabeto et al., 2001). constancy of trace element ratios between basic and felsic melts (e.g., zr/nb; fig. 6b and c) is often cited as strong evidence that fractional crystallization has been the dominant process in their evolution (weaver, 1977; wilson, 1989). at given zr content most rift margin samples show higher nb contents than do the rift center samples. kamber and collerson (2000) have indicated that nb is more sensitive to variations in degrees of partial melting than zr, and hence can be used to decipher the influence of variable degrees of melting. in this regard, some rift margin samples from the furi and yerer mountains have nb contents as low as the rift center samples (table 1; figs. 4 and 6b). it is evident that yerer and furi mountains are compositionally closer to rift center composition than the wechecha and menagesha mountains. furthermore, samples from yerer and furi are younger and have a narrower age range (2.03-4.04 ma) than the wechacha and mengasha mountains samples (3.09-6.63 ma) (chernet et al., 1998) (fig.6). mekelle university issn: 2073-073x 14 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 plotting zr/nb vs zr (fig. 6c) also shows that felsic volcanic rocks of the study area fall into two clusters. based on their zr/nb ratios, most samples from the rift margin plot along zr/nb ≤ 5, whereas rift center volcanic rocks, and the few samples from the yerer and furi mountains with low nb contents cluster along zr/nb ≥ 6. similarly, zr/nb ratios in the basic rocks of the two sequences also vary (fig. 6c). the rift center basic rocks have zr/nb ratio ≥ 5, whereas most of the basalts from the addis ababa area that are thought to be parental to the rift margin felsic volcanic rocks, and a few rift center basic rocks; have zr/nb ≤ 5. zr/nb ratios in volcanic rocks may also reflect crustal contamination,titanite fractionation or variation in degree of partial melting (wilson et al., 1995; kamber and collerson, 2000; kabeto et al., 2001). for example, basaltic sample et1201 from the plateau unit (table 1) has a zr/nb ratio of 13.0. et1201 has a very low initial ndisotopic ratio (0.51222 ± 8) compared to other basic lavas with lower zr/nb ratios, which may indicate that the higher zr/nb ratio reflects crustal involvement (kabeto et al. 2001). hence, we consider the rift center volcanic rocks (zr/nb > 6), and those rift margin volcanic rocks with zr/nb ratios > 5, to reflect either crustal input, titanite fractionation (fig. 6c) or different sources. the clear differences in crustal thickness, extensional tectonics, age of volcanic activity (morton et al., 1979; makris and ginzburg, 1987; wolde, 1996; abebe et al., 1998; boccaletti et al., 1999), and compositions of volcanic rocks in the two regions suggest that they were derived from different parantal magmas. the role of parental basic magma compositions in the rift margin and center felsic melts must be considered in the light of elevated or depleted absolute trace and major element abundances and the degree of silica saturation. furthermore, the effects of crustal contamination must be accounted for. for example, the silica saturation in the felsic volcanic rocks in the rift center could be produced by substantial contamination of the basic magma that is parental to most of the pliocene rift margin eruptives by silica-rich crust. however, this is an unsuitable mechanism to produce the felsic volcanic rocks from the rift center, because open-system behavior would produce higher incompatible trace element abundances in the more contaminated series (depaolo, 1981; nelson and davidson, 1993). this is not observed here. moreover, the ndisotopic compositions of the felsic rift center volcanic rocks lie within the range of basic volcanic rocks in the region (fig. 5). the lowest ndisotopic ratios are noted only in those felsic volcanic rocks at the rift margin that show higher degree of contamination. mekelle university issn: 2073-073x 15 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 figure 6. (a) plot of cao/al2o3 ratio against sio2, showing the two apparent evolution trends for the northern mer. most rift margin volcanic rocks plot at lower ratios. (b) linear correlation between zr and nb contents. samples generally plot along zr/nb = 5 and zr/nb = 7, which may indicate different sources or crustal input (see text for discussion). (c) zr/nb vs zr plot for the volcanic rocks. arrows show assumed afc and differentiation trends (fc) for rift margin and center sequences from different basic parent. the shaded area on (b) and (c) indicate samples from furi and yerer mountains overlapping the samples from the rift center (see text for discussion). data for crustal rocks from davidson and wilson (1989). symbols as in fig. 2. alternatively, contamination of basic magma, thought to be the parent for rift center felsic products by bulk assimilation of silica deficient crustal material (amphibolitic or basic crust?) must also be considered. this would make the rift margin wechecha unit magmas more contaminated than rift center felsic magmas (nelson and davidson, 1993). we consider this to be unlikely, as it cannot explain the relative depletion of the compatible elements mgo and cao in the wechecha samples (fig. 3). it appears that differing degrees of partial melting of the mantle source mekelle university issn: 2073-073x 16 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 provide the best explanation for the compositional differences seen between the two volcanic sequences (nelson and davidson, 1993). a lower degree of melting, deeper partial melting (kushiro, 1968; o’hara, 1968) or melting in the presence of co2 (davies and macdonald, 1987) could easily have produced incompatible element-enriched magma that differentiated to produce the most felsic rift margin samples. in contrast, higher degrees of melting could produce incompatible element depleted magmas that subsequently differentiated to produce the rift center felsic volcanic rocks. it has been suggested that basic lavas produced by low degrees of mantle partial melting have high incompatible element contents (e.g., zr, nb, y, k, and rb), high al2o3, and low sio2 and cao (tatsumi and kimura, 1991; wolde, 1996; kabeto et al., 2001b). in contrast, basic lavas that are produced by high degrees of partial melting have lower incompatible element and al2o3 contents, but higher cao and sio2. wolde (1996) has shown that alkali basalts produced by a low degree of partial melting are common in the western part of the rift and the margin, and are found only locally east of debre zeit (the rift center). in contrast, transitional basalts which originate from higher degrees of partial melting are commonly found within the rift center, where thinning of the crust has been identified from seismic refraction studies (makris and ginzburg, 1987). moreover, abebe et al. (1995) have suggested that the degree of alkalinity in basaltic melts increases away from the rift center. in the northern mer, the felsic melts in the rift center generally have lower al2o3, k2o, zr, nb, y, rb, and sr and higher sio2 and cao than most rift margin equivalents (figs. 3 and 4). hence, the major and trace element contrasts in the felsic products between the two regions could originate from compositional differences in their basaltic parents. wilson et al. (1995) demonstrated that compositional differences between silica-undersaturated and oversaturated felsic melts in the continental magmatism of the central massif (france) were controlled by subtle compositional differences between their respective basic magmas. in line with this suggestion kabeto et al. (2001) have considered that silica-saturated (basalt-trachyte) and silicaundersaturated (basanite-phonolite) lineages in the northern kenyan rift sector (lippard, 1973) originated from compositional differences in their parental basic magmas, and both felsic by differentiation combined with a little assimilation. this is also likely to be the case here. mekelle university issn: 2073-073x 17 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 5.2. fractional crystallization and/or degree of partial melting the general decrease of ni, cr, sr, ba, mgo, cao, ∑feo, tio2, and p2o5 with increasing sio2 (figs. 3 and 4; table 1) indicates that the geochemical evolution of these volcanic rocks was governed by fractionation of olivine, clinopyroxene, fe-ti oxide, feldspars, and apatite. tio2 and p2o5 also show to decrease at the same sio2 content in all rock suites, indicating simultaneous apatite and fe-ti oxide fractionation. moreover, the general increase in zr, nb, rb, y, and k concentrations with increasing sio2 is also consistent with fractional crystallization from a similar basic parent, to produce the mugearites, benmoreites, trachytes, and rhyolites of both regions. the well-defined linear correlation between zr and nb contents in the sequences (fig. 6b and c) also suggests that fractional crystallization was a dominant process. the srand ndisotopic ratios of the felsic lavas (fig. 5) also do not lie wholly within the isotopic range of their associated basic lavas, indicating that fractional crystallization was not the only process responsible for their genesis. genesis of the felsic mer volcanic rocks by anatexis of the upper continental crust must be discarded on the basis of geochemical characteristics. the afro-arabian continental crust displays a wide range of isotopic composition (davidson and wilson, 1989; hegner and pallister, 1989; möller et al., 1998) which is dissimilar to the felsic mer volcanic rocks (table 1). the ndisotopic compositions of most felsic mer volcanic rocks are also more radiogenic than mean upper crust. hence, partial melting of the upper continental crust cannot be the source for the felsic melts. low degrees of partial melting of basic lower crust and/or underplated basic magmas as possible source for the felsic melts can be tested by batch melting modeling calculations (shaw, 1970; skjerlie and johnston, 1993) performed on rb vs sr (not shown). based on the srisotopic variations between the basic (0.70349 to 0.70456) and felsic (0.70446 to 0.70783) volcanic rocks (table 1; fig. 5), it is possible that fractional crystallization might not be the only process responsible for the generation of felsic lavas. even if the data appears to be explained well by fractional crystallization from a basaltic parent, the fractionation stage could be an open system, and hence some assimilation of crustal material is possible. the estimation of the extent of contamination by crustal material is complicated by the diversity shown by araboafrican basement rocks (hegner and pallister, 1989; davidson and wilson, 1989; möller et al., 1998). mekelle university issn: 2073-073x 18 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 the sr-nd isotopic compositions of the felsic volcanic rocks from the rift margin also suggest that assimilation of crustal material has occurred may be limited. initial ndisotopic ratios, which are insensitive to small degrees of contamination, are variable and range from 0.51276 to 0.51237. hence, we favor fractional crystallization from different basic parents, combined with assimilation of crustal materials, over a combined partial melt and fractionation origin for the felsic volcanic rocks. 5.3. assimilation and fractional crystallization (afc) a conventional way of identifying crustal contamination in a suite is to show that 87sr/86sr and 143nd/144nd initial ratios vary systematically (increase and/or decrease) with increasing degree of differentiation. using sio2 as a fractionation index, most of the felsic rocks here show an overall increase in sr-isotopic ratio (fig. 7b). most intermediate samples from the wechecha and boseti units exhibit lower ndisotopic ratios than the highly felsic samples, suggesting higher rates of contamination occurred in the intermediate lithotypes (kabeto et al., 2001). the felsic volcanic samples from the study area apparently plot along afc trend (fig. 7a), with some scatter. figure 7. plots of (a) initial srand (b) nd isotopic ratios against sio2 for the northern mer volcanic rocks. the felsic rocks plot on two apparent afc trends. apparent afc and differentiation trends (fc) are also shown. the ndisotopic ratios also show variations with sio2 (see text for discussion). symbols as in fig. 2. few mineral aggregates and resorbed feldspar with melt inclusions were observed during our petrographic investigation. although this could indicate magma mixing or assimilation, complete mixing can be excluded, because no straight line mekelle university issn: 2073-073x 19 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 relationships exist on simple binary plots such as sio2-mgo (fig. 3). therefore, we consider that magma mixing is a minor process in the genesis of the felsic volcanic rocks. figure 8. graphical presentation of the assimilation-fractional crystallization (afc) model (depaolo, 1981). (a) plot of initial 87sr/86sr vs sr (ppm), model afc curves calculated using an average sudanese upper crust as an assimilant (davidson and wilson, 1989; 87sr/86sr = 0.727967, 143nd/144nd = 0.511367, sr = 426, nd = 9.6, and nb = 10 ppm) and starting basic parent et1602 (table 1). symbols as in fig. 2. the elemental and sr-nd isotopic compositions (e.g., table 1; figs. 4 , 5, 6b, 6c, and 7) of the felsic rocks provide evidence of operation of both fractional crystallization and some crustal assimilation (afc) (depaolo, 1981). afc calculations were carried out using sample et1602 (143nd/144nd = 0.512894, and 87sr/86sr = 0.70350; table 1) as starting basaltic compositions and using depaolo’s (1981) equations (fig. 8). it is assumed that the rock examined was little modified by crustal contamination, and that crustal influence is of minor importance (isotopically) in the basaltic sample. for example, sample et1602 has higher 143nd/144nd and lower 87sr/86sr ratios than rhyolite et1302a, which is most radiogenic (87sr/86sr = 0.70727 and mekelle university issn: 2073-073x 20 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 143nd/144nd = 0.51273). in addition, the isotopic variability among the basalts is very small (fig. 5; table 1) compared to the diversity shown by arabo-african basement rocks (cohen et al., 1984; hegner and pallister, 1987; davidson and wilson, 1989; halliday et al., 1991; möller et al., 1998). hence, the choice of initial compositions is therefore not critical for the afc calculations (fig. 8). several calculations were made taking r (assimilation rate/crystallization rate ratio) to be 0.001, 0.01, 0.1, 0.3, 0.5, and 0.6. for each model, we assumed dsr = 3.2, dnb = 0.3, and dnd = 0.45. the d values used are similar to those in the compilation of rollinson (1995). an example of afc calculation performed from the average of the sudanese upper crust (davidson and wilson, 1989, 87sr/86sr = 0.72797, sr = 426 ppm, and 143nd/144nd = 0.51137, nb = 9.6, nd = 24 ppm) is shown in fig. 8a and b, with basalt sample et1602 taken as the basic parent. assimilation of the assumed crustal rock by strongly differentiated trachytes and rhyolites at low mass assimilation to mass crystallization rates (r = 0.001-0.6), and moderate to high f values (> 0.1 on afc curves) can produce the samples which exhibit high 87sr/86sr, low sr (< 185 ppm), low 143nd/144nd and high nb (> 200 ppm). 87sr/87sr ratios plotted against sr concentration (fig. 8a) clearly show the effects of afc. the data describes a curved differentiation trend with a sharp inflection around the highly felsic compositions, reflecting the strong influence of plagioclase fractionation with concomitant decrease in sr (figs. 4 and 8). the hypothetical trend describes the general differentiation trend among the felsic rocks, along which ni, cr, cao, and mgo contents broadly decrease. such hypothetical curves were also tested in the jebel marra area of the sudan (davidson and wilson, 1989) and were successfully applied to northern kenyan felsic lavas (kabeto et al., 2001), to examine the evolution of basaltic to trachytic and phonolitic magmas. relatively higher rates of assimilation are calculated for intermediate rocks (fig. 8a and b). this may be explained by differentiation of intermediate magmas at deeper levels in the crust, where higher ambient wallrock temperatures and presence of hot basic magmas would facilitate higher rates of assimilation (davidson and wilson, 1989; macdonald et al., 1995; panter et al., 1997). furthermore, high rates of assimilation (0.3-0.6) are evident for most felsic volcanic rocks from the rift margin (fig. 8b), indicating a greater degree of contamination than at the rift center. this is also in agreement with the thicker crust at the rift margin than at the rift center (makris and ginzburg, 1987). mekelle university issn: 2073-073x 21 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 6. conclusions studies of the northern main ethiopian rift (mer) volcanic rocks offer insight into the genetic relations of basic and felsic volcanic rocks, and establish that compositional contrasts occur in equivalent volcanic rocks at rift margin and center magma series within a single intraplate continental setting. higher al2o3, k2o, zr, nb, sr, and rb and lower cao, cao/al2o3, and zr/nb concentrations in the rift margin felsic volcanic rocks erupted mostly in the pliocene compared to the quaternary equivalents in the rift center reflect inheritance from their basic parents. the spatial and temporal distinctions between the volcanic suites in the study area and their markedly different geochemistry are explained by evolution along separate magma trends. hence, alkaline basaltic melts produced by lower degrees of partial melting are a possible source for most of the felsic volcanic rocks at the rift margin. in contrast, transitional basaltic melts produced at high degrees of partial melting are thought to be the parent for the felsic volcanic rocks in the rift center. modeling of the geochemical variations suggests that crystal-liquid fractionation processes within the shallow reservoirs were dominant during most trachyte-rhyolitic production in the rift center, along with less well-developed afc processes. afc appears to play a greater role in the genesis of intermediate rift center rocks and felsic rocks at the rift margin. we consider this to partly be a function of depth of fractionation of the magmas, implying that intermediate and rift margin magmas differentiated at deeper levels, whereas the more felsic trachytes and rhyolites of the rift center originated at shallow crustal levels. this is also in agreement with known variation in crustal thickness, variation as thinner crust is present in the rift center than at the rift margin. 7. acknowledgments we thank prof. s. iizumi for his help with isotope analyses and dr. t. bary for afc model calculation and discussion. k. kabeto acknowledges financial support from japan society for promotion of science (jsps) during post doctoral research at shimane university. thanks are also due to prof. k. koeberl, dr. d. kuester and dr. k. bheemalingeswara for providing critical comments and constructive suggestions that have undoubtedly improved the quality of the paper. 8. references abebe, t., mazzarini, f., innocenti, f. & manetti, p. 1998. the yerer-tullu wellel volcanotectonic lineament: a transtensional structure in central ethiopia and the associated magmatic activity. j. afr. earth sci., 26:135-150. mekelle university issn: 2073-073x 22 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 abebe, t. 1995. l’allineamento vulcano-tettonica yerer-tullu wellel (etiopia centrale): evoluzione petrologica e volcanologica di un sistema transversale al rift etiopico. phd thesis university of florence, dipartimento di scienze della terra, (unpubl.). ayalew d., barrey, p., marty, b., reisberg, l., yirgu, g. & pik. r. 2002. source, genesis, and timing of giant 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central, france. j. petrol., 36: 17291753. wolde, b. 1996. spatial and temporal variations in the compositions of upper miocene to recent basic lavas in the northern main ethiopian rift: implications for the causes of cenozoic magmatism in ethiopia. geol. rundsch, 85: 380-389. woldegabreil, g., aronson, j.l. & walter, r.c. 1990. geology, geochronology and rift basin development in the central sector of the main ethiopian rift. geol. soc. bull., 102: 439458. kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 table 1. chemical and sr-nd isotopic compositions of selected samples from the northern mer. abbreviations are: nd = not detected; – = not measured; m = measured ratio; i = initial ratio, tra = trachyte, rhy = rhyolite, benm = benmoreite, ha = hawaite, ba = basalt, igni = ignimbrite, and obs/pst = obsidian/pitchstone. major oxides in wt.% and trace elements in ppm. major and trace element oxides are recalculated to 100% on an hydrous basis. ages from morton et al. (1979) and boccaleti et al. (1999). unit nazreth boseti sample no. et14 et 971602 et 117 et1607 et1608 et 1702a et1504 et1507 et1505 et1501 et1506 et1605 et1604b et1603b locality tafu kone barko harbona kimbo boku boseti boseti boseti wolenchiti boseti hada hada hada rock type trachyte rhyolite rhyolite rhyolite rhyolite rhyolite benmoreite trachyte trachyte trachyte rhyolite trachyte rhyolite rhyolite age (ma) 0.6 0.3 0.5 0.6 0.83 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 sio2 67.98 68.84 71.72 69.35 69.67 73.78 56.24 65.44 66.82 66.90 69.66 66.61 67.19 68.00 tio2 0.59 0.41 0.40 0.38 0.61 0.31 2.13 0.63 0.41 0.47 0.32 0.45 0.41 0.41 al2o3 14.07 13.02 11.00 14.94 15.35 10.85 15.38 12.07 13.71 14.50 9.84 15.42 15.18 15.04 fe2o3 0.85 0.93 0.92 0.59 0.42 0.82 1.52 1.48 1.02 0.91 1.22 0.84 0.82 0.80 feo 4.34 4.73 4.74 2.99 2.14 4.16 8.33 7.54 5.20 4.66 6.24 4.30 4.17 4.06 mno 0.21 0.19 0.21 0.16 0.15 0.15 0.31 0.30 0.22 0.23 0.26 0.16 0.16 0.16 mgo 0.32 0.06 0.03 0.22 0.44 0.02 2.60 0.48 0.01 0.09 0.22 0.14 0.13 cao 1.68 0.67 0.44 0.58 0.85 0.27 5.14 1.04 0.72 1.10 0.29 1.64 1.48 1.47 na2o 5.86 6.82 5.77 6.57 6.16 5.02 5.56 7.49 7.89 6.38 8.04 6.38 6.22 5.90 k2o 3.99 4.30 4.77 4.17 4.12 4.62 1.99 3.47 3.98 4.72 4.12 3.92 4.20 3.99 p2o5 0.09 0.03 0.01 0.04 0.09 0.80 0.05 0.02 0.03 0.01 0.06 0.04 0.04 loi 1.47 1.48 2.10 0.20 0.20 2.45 0.29 1.07 0.73 1.08 1.98 0.45 alkali total 9.85 11.12 10.53 10.74 10.28 9.64 7.55 10.96 11.87 11.10 12.16 10.29 10.42 9.89 agpaitic index 0.99 1.22 1.33 1.03 0.95 1.22 0.73 1.33 1.26 1.08 1.80 0.96 0.97 0.93 mg number 11.75 2.08 1.05 11.70 26.95 1.04 35.76 10.22 0.47 3.23 8.47 5.64 5.36 mekelle university issn: 2073-073x 27 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit plateau addis ababa wechecha rift center mafic sample no. et1201 et1303 et1602 et1403 et1203b et1405 et1404a et1203a et1302 et1301 et1606 et1508 et1507b locality intoto wechecha addis akaki menagesha yerer yerer menagesha wechecha wechecha wonji sodorei boku rock type basalt basalt basalt basalt benmoreite benmoreite benmoreite trachyte trachyte rhyolite basalt basalt hawaiite age (ma) 22.8 7.5 7 7 4 3.09 3.09 3.6 4 4.6 0.5 0.5 0.5 sio2 47.20 46.32 45.69 46.71 57.02 60.46 62.59 65.47 68.20 68.50 47.81 48.33 52.16 tio2 1.72 2.24 2.63 2.21 2.08 1.14 0.92 0.27 0.21 0.22 1.92 2.32 2.20 al2o3 21.17 14.75 15.52 15.21 15.48 16.44 16.53 17.79 15.85 16.00 14.12 15.14 15.56 fe2o3 1.55 1.76 1.89 1.72 1.39 1.26 1.10 0.63 0.62 0.61 1.77 1.85 1.76 feo 7.93 8.97 9.65 8.76 7.50 6.41 5.63 3.20 3.17 3.10 9.04 9.42 8.99 mno 0.14 0.18 0.16 0.17 0.33 0.13 0.13 0.11 0.08 0.07 0.17 0.17 0.21 mgo 4.24 10.81 9.77 9.57 2.19 0.98 0.75 0.06 0.02 0.01 10.42 7.73 4.94 cao 12.51 11.26 9.66 11.62 4.37 3.30 2.01 0.31 0.36 0.22 11.29 10.55 8.02 na2o 2.67 2.50 3.41 2.84 5.55 4.62 5.50 7.02 6.51 6.21 2.43 2.93 4.11 k2o 0.63 0.79 1.07 0.80 3.14 4.86 4.56 5.12 4.97 5.03 0.66 0.92 1.31 p2o5 0.25 0.42 0.56 0.40 0.93 0.41 0.28 0.02 0.01 0.03 0.37 0.64 0.73 loi 1.06 1.61 0.20 1.47 1.48 0.19 0.74 1.47 1.57 1.07 1.60 0.54 0.76 alkali total 3.29 3.28 4.48 3.64 8.69 9.48 10.06 12.14 11.48 11.23 3.09 3.85 5.42 agpaitic index 0.24 0.34 0.44 0.36 0.81 0.78 0.85 0.96 1.02 0.98 0.33 0.38 0.53 mg number 48.83 68.23 64.34 66.08 34.25 21.39 19.14 3.31 0.95 0.81 67.26 59.39 49.51 mekelle university issn: 2073-073x 28 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit rift center mafic gedemsa nazreth sample no. et 941503a et 941502 et 1706 et 941503b et60 et54 et38 et 9865 et 9840 et06 et103 et94 locality d.zeit d.zeit mojo d.zeit sololuya gedemsa alula gedemsa koka gedemsa gedemsa bulbula rock type basalt basalt basalt basalt rhyolite rhyolite obsidian rhyolite rhyolite obsidian ignimbrite ignimbrite age (ma) 0.6 0.6 1 0.5 0.5 0.6 0.6 0.5 0.5 0.5 0.6 0.5 sio2 49.09 46.38 49.45 49.08 71.88 72.19 72.69 73.59 72.91 72.34 73.47 67.14 tio2 1.35 1.65 1.95 2.24 0.33 0.32 0.31 0.27 0.35 0.31 0.33 0.69 al2o3 16.16 13.00 17.45 15.88 12.92 12.85 10.86 9.57 9.89 12.61 9.15 14.26 fe2o3 1.51 1.73 1.76 1.92 0.62 0.62 0.89 1.07 0.94 0.61 1.00 0.91 feo 7.70 8.81 8.96 9.80 3.21 3.20 4.59 5.51 4.81 3.13 5.16 4.66 mno 0.14 0.16 0.14 0.18 0.13 0.13 0.17 0.23 0.21 0.12 0.22 0.21 mgo 9.28 13.93 6.27 6.36 0.13 0.12 0.06 0.11 0.05 0.06 0.05 0.52 cao 11.00 11.15 9.43 9.42 0.70 0.65 0.41 0.30 0.35 0.55 0.85 1.78 na2o 2.34 2.26 3.30 3.43 5.13 5.23 5.65 4.83 5.94 5.16 5.29 5.75 k2o 1.17 0.64 0.91 1.06 4.95 4.67 4.30 4.51 4.55 5.09 4.48 3.97 p2o5 0.25 0.30 0.38 0.64 0.01 0.01 0.06 0.01 0.00 0.00 0.13 loi 0.11 0.17 1.12 0.86 0.22 0.18 1.17 alkali total 3.51 2.91 4.21 4.49 10.07 9.90 9.96 9.34 10.49 10.24 9.77 9.72 agpaitic index 0.32 0.09 0.37 0.43 1.07 1.06 1.28 1.34 1.49 1.11 1.48 0.96 mg number 68.23 73.81 55.51 53.65 6.61 6.33 2.30 3.52 1.86 3.55 1.67 16.57 mekelle university issn: 2073-073x 29 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit plateau addis ababa wechecha rift center mafic sample no. et1201 et1303 et1602 et1403 et1203b et1405 et1404a et1203a et1302 et1301 et1606 et1508 et1507b locality intoto wechecha addis akaki menagesha yerer yerer menagesha wechecha wechecha wonji sodorei boku rock type basalt basalt basalt basalt benmoreite benmoreite benmoreite trachyte trachyte rhyolite basalt basalt hawaiite cr 32 672 331 491 5 20 17 19 16 19 558 245 36 ni 15 231 185 154 8 2 3 7 8 2 208 107 52 ba 160 361 301 446 1,001 89 1,267 48 143 151 274 467 1,456 nb 15.7 33.1 47.1 31.4 106.5 108.0 104.6 231.7 192.2 166.0 20.4 28.5 26.1 zr 110.5 125.6 232.6 122.4 481.2 774.8 745.0 1,104 965.4 818.4 117.7 174.9 157.1 y 15.1 23.7 23.8 20.7 65.0 66.2 82.0 74.9 204.8 44.3 21.2 16.3 28.0 sr 792.6 675.8 643.7 629.0 540.0 313.0 276.1 5.3 5.6 6.6 401.6 481.4 466.9 rb 19.2 16.6 16.6 16.2 79.0 119.3 120.1 189.5 159.3 151.1 12.0 16.0 16.9 la 12.9 24.4 24.9 21.7 93.3 104.2 175.3 694.2 17.8 17.0 24.3 28.9 ce 28.7 47.8 55.9 45.4 191.5 183.0 152.1 229.0 74.9 37.3 52.9 63.3 pr 3.7 5.9 6.9 5.5 22.1 22.3 25.0 25.0 4.3 4.8 6.6 8.3 nd 15.8 24.9 28.3 23.5 84.5 83.3 99.8 100.0 16.0 20.7 26.9 sm 3.6 5.2 5.8 5.0 15.9 15.5 14.6 30.0 4.0 4.7 5.6 eu 1.3 1.8 1.9 1.7 3.8 3.7 0.8 5.0 0.8 1.6 2.1 3.5 gd 3.5 5.2 5.5 4.8 13.7 13.9 10.4 20.0 4.8 4.6 5.7 7.1 tb 0.5 0.8 0.8 0.7 2.1 2.1 1.8 5.0 1.0 0.7 0.8 1.0 dy 3.1 4.4 4.5 4.2 12.9 13.3 12.0 20.0 7.9 4.2 4.7 5.7 ho 0.6 0.8 0.8 0.8 2.5 2.7 2.6 6.7 1.8 0.8 0.9 1.1 mekelle university issn: 2073-073x 30 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit plateau addis ababa wechecha rift center mafic sample no. et1201 et1303 et1602 et1403 et1203b et1405 et1404a et1203a et1302 et1301 et1606 et1508 et1507b locality intoto wechecha addis akaki menagesha yerer yerer menagesha wechecha wechecha wonji sodorei boku rock type basalt basalt basalt basalt benmoreite benmoreite benmoreite trachyte trachyte rhyolite basalt basalt hawaiite er 1.6 2.3 1.9 2.2 7.2 8.0 8.1 17.7 5.9 2.2 2.2 2.9 tm 0.2 0.3 0.3 0.3 1.0 1.1 1.3 2.4 0.9 0.3 0.3 0.4 yb 1.3 1.9 1.8 1.8 6.9 7.4 8.8 15.6 6.6 1.9 2.0 2.5 lu 0.2 0.3 0.2 0.3 1.0 1.1 1.4 2.2 1.0 0.3 0.3 0.4 hf 2.6 3.0 5.2 3.0 17.6 17.3 23.2 21.7 18.5 2.9 3.5 3.8 ta 1.0 1.9 5.7 1.9 6.1 5.8 13.7 10.6 9.1 1.2 2.5 1.5 th 1.2 2.2 2.4 2.2 14.5 14.2 31.9 24.2 20.9 1.5 2.0 2.3 u 0.3 0.5 0.6 0.5 3.4 3.4 3.7 3.4 2.8 0.4 0.6 0.4 zr/nb 7.04 3.79 4.94 3.90 4.52 7.17 7.12 4.76 5.02 4.93 5.77 6.15 6.02 isotope (87sr/86sr) i 0.70376 0.70383 0.70350 0.70368 0.70387 0.70489 0.70490 0.70504 0.70727 0.70624 0.70427 0.70441 0.70456 (143nd/144nd) i 0.51222 0.51281 0.51289 0.51288 0.51264 0.51262 0.51264 0.51276 0.51273 0.51237 0.51276 0.51279 0.51270 mekelle university issn: 2073-073x 31 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit rift center mafic gedemsa nazreth sample no. et 941503a et 941502 et 1706 et 941503b et60 et54 et38 et 9865 et 9840 et06 et103 et94 locality d.zeit d.zeit mojo d.zeit sololuya gedemsa alula gedemsa koka gedemsa gedemsa bulbula rock type basalt basalt basalt basalt rhyolite rhyolite obsidian rhyolite rhyolite obsidian ignimbrite ignimbrite age (ma) 0.6 0.6 1 0.5 0.5 0.6 0.6 0.5 0.5 0.5 0.6 0.5 cr 298 822 114 139 14 9 28 13 12 16 13 15 ni 148 380 46 73 28 28 17 28 27 25 28 27 ba 331 278 320 518 491 492 183 128 53 397 66 1,246 nb 24.1 26.6 26.4 32.2 104.1 103.7 100.9 140.0 128.6 109.8 113.9 75.4 zr 106.1 109.7 143.8 165.5 761.2 764.1 791.3 1,077 918 813.8 668.8 503.1 y 17.6 19.0 24.4 28.1 74.8 74.6 93.5 60.0 94.3 82.2 62.7 48.3 sr 466.6 461.6 555.0 635.9 21.5 20.2 10.9 9.5 3.5 16.0 11.7 179.3 rb 20.3 15.7 15.1 17.3 115.2 113.6 111.2 140.2 120.3 129.9 128.6 82.9 la 18.7 18.5 25.4 29.6 93.9 87.7 112.8 109.5 107.3 96.0 59.2 ce 37.8 38.1 48.8 62.6 185.6 185.6 226.0 279.8 224.2 196.1 123.3 pr 4.5 4.7 6.5 7.7 22.0 20.6 25.0 25.0 25.0 22.3 14.2 nd 18.2 19.2 27.2 32.1 81.2 76.6 100.0 100.0 95.8 82.6 54.8 sm 3.8 4.1 5.6 6.6 15.8 15.2 20.5 21.2 19.3 16.6 10.9 eu 1.4 1.4 1.9 2.2 2.0 2.0 3.1 3.0 2.2 2.1 3.1 gd 3.7 4.1 5.4 6.3 13.9 13.6 18.2 17.9 17.7 14.8 9.8 tb 0.6 0.6 0.8 0.9 2.3 2.2 3.0 2.9 2.9 2.5 1.6 dy 3.4 3.8 4.9 5.5 14.5 14.1 18.6 17.5 18.1 15.6 9.7 ho 0.7 0.7 0.9 1.1 2.9 2.8 3.7 3.3 3.7 3.1 1.9 mekelle university issn: 2073-073x 32 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit rift center mafic gedemsa nazreth sample no. et 941503a et 941502 et 1706 et 941503b et60 et54 et38 et 9865 et 9840 et06 et103 et94 locality d.zeit d.zeit mojo d.zeit sololuya gedemsa alula gedemsa koka gedemsa gedemsa bulbula rock type basalt basalt basalt basalt rhyolite rhyolite obsidian rhyolite rhyolite obsidian ignimbrite ignimbrite age (ma) 0.6 0.6 1 0.5 0.5 0.6 0.6 0.5 0.5 0.5 0.6 0.5 er 1.9 2.0 2.6 3.0 8.4 8.4 10.6 9.3 10.7 9.2 5.5 tm 0.3 0.3 0.4 0.4 1.2 1.2 1.5 1.4 1.6 1.3 0.8 yb 1.7 1.8 2.3 2.7 8.2 8.2 10.0 9.6 10.2 8.9 5.4 lu 0.3 0.3 0.3 0.4 1.2 1.2 1.4 1.4 1.5 1.3 0.8 hf 2.5 2.6 3.5 3.9 18.7 18.5 19.2 26.4 22.3 19.9 12.4 ta 1.4 1.6 1.5 1.8 6.1 6.1 5.9 8.1 7.5 6.7 4.3 th 2.1 2.1 2.1 2.2 16.0 15.7 15.2 20.4 16.9 16.7 9.8 u 0.6 0.5 0.5 0.5 3.6 3.7 3.6 1.2 4.0 3.9 1.9 zr/nb 4.40 4.12 5.45 5.14 7.31 7.37 7.84 7.69 7.14 7.41 5.87 6.67 isotope (87sr/86sr) i 0.70476 0.70469 0.70783 0.70463 0.70459 0.70589 (143nd/144 nd) i 0.51278 0.51278 0.51273 0.51282 0.51278 0.51281 mekelle university issn: 2073-073x 33 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit nazreth boseti sample no. et14 et 971602 et 117 et1607 et1608 et1702a et1504 et1507 et1505 et1501 et1506 et1605 et1604b et1603b locality tafu kone barko harbona kimbo boku boseti boseti boseti wolenchiti boseti hada hada hada rock type trachyte rhyolite rhyolite rhyolite rhyolite rhyolite benmoreite trachyte trachyte trachyte rhyolite trachyte rhyolite rhyolite cr 10 18 11 17 20 13 25 20 16 17 16 20 17 ni 28 1 28 1 2 26 10 2 1 2 4 2 2 3 ba 1,290 602 95 974 857 67 657 1,974 821 461 394 968 695 973 nb 81.7 126.7 111.9 114.2 92.1 129.2 33.8 85.1 109.1 92.4 160.8 88.0 92.3 91.3 zr 539.7 579.0 772.3 756.4 686.9 1,024 161.4 492.9 706.7 528.0 1,065 645.6 680.0 679.4 y 55.5 91.0 56.7 58.2 70.5 80.3 22.6 68.5 80.9 62.8 129.5 65.8 69.2 65.8 sr 156.3 32.2 3.0 21.8 114.9 3.9 578.4 28.3 12.8 6.7 5.4 110.4 83.2 100.8 rb 85.0 111.8 122.1 95.0 110.2 148.9 21.7 56.9 97.3 78.6 142.9 97.5 103.4 103.8 la 65.7 91.6 93.6 82.5 85.3 106.3 27.4 61.2 82.4 65.4 129.8 73.1 75.9 74.5 ce 135.0 185.3 168.7 165.8 175.4 215.2 55.7 130.0 169.3 136.5 267.0 148.8 153.2 152.9 pr 15.9 21.1 23.3 19.8 20.3 24.8 6.6 25.0 19.6 16.0 15.6 17.0 17.7 17.4 nd 60.5 80.0 87.5 75.0 77.0 91.4 26.5 100.0 75.6 62.0 62.4 64.2 66.3 66.5 sm 12.2 16.3 17.0 14.5 14.9 17.9 5.4 24.7 15.6 12.7 13.2 12.8 13.3 13.2 eu 3.4 3.3 2.4 2.9 3.4 2.4 1.8 5.0 3.6 2.2 4.2 3.1 2.9 3.0 gd 11.0 15.3 14.2 12.3 13.1 15.9 5.1 20.0 14.8 11.7 12.9 11.9 12.3 12.1 tb 1.8 2.6 2.3 2.0 2.1 2.6 0.8 4.0 2.5 1.9 2.1 2.0 2.0 2.0 dy 11.0 16.8 13.9 12.5 13.1 15.9 4.5 20.0 15.5 12.0 13.4 12.5 13.0 12.6 ho 2.2 3.5 2.7 2.5 2.6 3.1 0.9 5.0 3.1 2.4 2.7 2.5 2.6 2.6 mekelle university issn: 2073-073x 34 kurkura et al., (mejs) volume 1 (1): 4 – 35, 2009 (continued) unit nazreth boseti sample no. et14 et 971602 et 117 et1607 et1608 et1702a et1504 et1507 et1505 et1501 et1506 et1605 et1604b et1603b locality tafu kone barko harbona kimbo boku boseti boseti boseti wolenchiti boseti hada hada hada rock type trachyte rhyolite rhyolite rhyolite rhyolite rhyolite benmoreite trachyte trachyte trachyte rhyolite trachyte rhyolite rhyolite er 6.3 10.5 7.7 7.1 7.7 8.8 2.4 14.7 9.2 7.2 7.8 7.5 7.8 7.6 tm 0.9 1.5 1.2 1.1 1.1 1.3 0.3 2.1 1.3 1.1 1.1 1.1 1.1 1.1 yb 6.1 9.9 8.0 7.7 7.5 8.6 2.1 13.6 8.6 7.2 7.2 7.3 7.6 7.3 lu 0.9 1.5 1.2 1.2 1.1 1.3 0.3 2.0 1.3 1.1 1.1 1.1 1.1 1.1 hf 13.1 19.2 18.7 17.8 16.3 22.9 3.7 25.8 16.5 12.9 11.8 15.2 15.9 15.9 ta 4.7 7.4 6.3 6.5 4.6 7.2 1.9 9.4 6.3 5.0 4.9 5.0 5.3 5.3 th 10.8 15.0 15.9 12.6 13.4 14.8 2.5 19.2 12.4 9.7 7.6 12.2 12.7 12.5 u 1.9 6.1 2.1 1.8 3.0 3.3 0.6 4.8 3.2 2.3 2.1 1.9 2.8 1.7 zr/nb 6.61 4.57 6.90 6.62 7.46 7.92 4.78 5.79 6.48 5.71 6.62 7.33 7.37 7.44 isotope (87sr/86sr) i 0.70502 0.70577 0.70477 0.70486 0.70628 0.70478 0.70553 0.70450 0.70538 0.70416 0.70447 0.70446 0.70474 (143nd/144nd) i 0.51277 0.51285 0.51266 0.51281 0.51279 0.51262 0.51285 0.51286 0.51284 0.51277 0.51261 0.51280 0.51274 mekelle university issn: 2073-073x 35 microsoft word 1. cover pages nata et al., (mejs) volume 1 (1): 36 – 58, 2009 groundwater suitability for irrigation: a case study from debre kidane watershed, eastern tigray, ethiopia *nata tadesse1, k. bheemalingeswara1 and asmelash berhane2 1department of earth science, college of natural and computational sciences, mekelle university, p.o. box 1604, mekelle, ethiopia (* tafesse24603@yahoo.com) 2department of larmep, college of dry land agriculture and natural resource management, mekelle university, mekelle, ethiopia abstract the present paper tries to assess groundwater suitability for irrigation purpose in debre kidane watershed (45.09 km2), northern ethiopia. the goal was to evaluate the suitability of the groundwater for irrigation, examine the water types and to investigate possible long and short term impact on groundwater quality. thirty six water samples each were collected in rainy and dry (irrigation) seasons from the active shallow hand dug wells. the well selection for detailed study and water sampling was done using stratified followed by random sampling technique. the number of wells selected for study is accounting 10% of the total available hand dug wells in the area. parameters such as electrical conductivity (ec), ph, total dissolved solids (tds), temperature and other physical properties were recorded in the field. major anions and cations (ca2+, mg2+, k+, na+, co32-, hco3-, cl-, so42and no3-) were analyzed in the laboratory. chemical data suggests that the water type in the area though varies from mg-hco3, ca-hco3, mg-cl, na-hco3 to khco3, predominantly it is mixed cation-hco3 type in the rainy season; and ca-hco3 (piper diagram) and na-hco3 (stiff diagram) in irrigation season. dominance of na in irrigation season and increase in sodium absorption ratio (sar) are primarily due to possible increase of na absorption in the soil replacing ca. according to the guidelines for irrigation water quality, the groundwater is suitable for irrigation with some minor exceptions. in rainy season, 89% of the samples fall under the water class “good” and 11% “permissible” whereas in irrigation season only 30% are classified as “good” and 70% under “permissible” class. toxicity in terms of sar and salinity though presently under control and there is no specific toxicity effect on vegetables and field crops, however, there are indications of their increase in due course of time if proper measures are not taken. keywords: groundwater, irrigation, salinity, sar, toxicity, water quality, hand dug well, ethiopia. 1. introduction water occurring either as surface or subsurface water is the mankind’s most vital and versatile natural resources. surface water exists in rivers, lakes, ponds, and oceans. surface water mainly rainwater by percolating through soil and weathered rock horizons occupies the subsurface permeable layers and develops into a groundwater. due to its interaction for longer period of mekelle university issn: 2073-073x 36 mailto:tafesse24603@yahoo.com nata et al., (mejs) volume 1 (1): 36 – 58, 2009 time with soil, weathered and fresh rock materials which in turn vary in composition, groundwater compared to surface water provides a wide range of variation in its composition. thus, the utility of groundwater depends not only on its abundance but also on its quality. groundwater utilization for irrigation and domestic purposes has been at a maximum compared others, like livestock and, industrial use etc., particularly due to food security problems and global climatic changes. thus groundwater has become an important source for irrigation and it has become an integral part of the irrigation strategy “to overcome food scarcity” in many developing countries including in african continent. such efforts have helped to expand irrigation with time particularly from 1950’s the expansion has been rapidly increasing (rosegrant et al., 1999). currently, it accounts for about 72% of global water withdrawals and about 90% in the case of developing countries. according to the ministry of water resources (2002), ethiopia is endowed with huge natural water resources, which include 122 billion m3 annual surface runoff and 2.9 billion m3 of groundwater. however, the county’s water resource has contributed little to the country’s socioeconomic development, because major part of the surface runoff is not utilized and at the same utilization of groundwater for irrigation is still in infantile stage. in the case of the tigray region the main economic means is rain fed agriculture. the region is characterized by undulating topography and experiences arid to semi-arid conditions with highly erratic and unreliable rainfall. thus the region is not in a position to cover the annual food requirement of its people. to alleviate the challenges of food insecurity in the country promotion of irrigated agriculture was given priority (mekuria, 2003). thus, hand dug well construction has become one of the activities both by the individuals as well as the government on a sustainable basis. implementation of this technology does not need high investment and skilled work force instead a household can easily adopt and practice it. however, the issue of sustainability in terms of quality and quantity which changes with time and type of practices in the field, demands attention. the changing conditions have provided impetus to develop irrigation using groundwater. debre kidane watershed in tigray is one such area where about 360 shallow hand dug wells were constructed primarily to overcome the moisture scarcity. the households benefited from these dug wells and started cultivating and producing different high value crops even two times a year. availability of water by itself is not a guaranty for sustainable development, but, its fitness to mekelle university issn: 2073-073x 37 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 specific purpose like irrigation, domestic and industries is important. since economic advantage alone cannot sustain the practice, the issues like ecological and social are to be taken in to account in the development and management of the irrigation schemes. quality of water should be made part of such studies. ultimately the knowledge of irrigation water quality is critical to understand what management changes are necessary for long-term and short term productivity particularly for crops that are sensitive to changes in quality (bohn et al., 1985; fao, 1985; brady, 2002). the present paper examines the quality of groundwater used for irrigation in debre kidane watershed (fig.1) and tries to a) determines suitability of groundwater for irrigation purpose; b) investigate the water types; c) record water salinity, sodicity if any; d) determine the possible sources for such variations; and, e) examine possible future trends in the toxicity. 1.1 description of the study area debre kidane watershed is located in the eastern tigray, north ethiopia. geographically, it is found bounded between 545000 – 553000m e and 1535000 – 1544000m n, and has an aerial coverage of 45.09 km2 (fig. 1) with a mean altitude of 2200 meters above sea level. the mean annual rainfall in the area is about 524.08 mm (nata, 2003). monthly rainfall is concentrated mostly in the mid of june to the mid of september. the drainage is well developed and originates from the elevated areas in the northeast and flow towards south west (fig. 1). northeastern elevated areas form the main recharge source for groundwater in the area. the mean annual temperature is 18.1ºc and the yearly average maximum and minimum temperatures are 25.1ºc and 10.8ºc, respectively. the annual range of temperature is 3.7ºc (nata, 2003). the dominant crops grown in the area are barley (hordeum vulgare), wheat (tritcum asteivum), teff (eragrostive teff), maize (zea mays), finger millet (pennisetum americanum), beans (phaseolus vulgaris) and peas (pistum sativum). soil texture observed in the field are sandy, light clay, silty, loamy sand, and loam. dominant soil texture being silt loam (nata et al., 2008). major soil of the watershed from along the inlet and outlet is vertisols, cambisol, leptosol, and alluvisol. in the study area the types of aquifers are localized, confined and unconfined types. confined aquifers are located in the discharge areas of the basins and the unconfined types are found in the recharge areas. out of the observed hand dug wells, 72.5% are located in unconfined aquifers and the remaining are in the confined aquifers (nata et al., 2008). mekelle university issn: 2073-073x 38 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 tigray amhara afar 40393837 12 13 14 15 0 18 miles 0 1 kilometer 1535000 1544000 545000 553000 n n (a) (b) streams figure 1. location and drainage map of the watershed (nata et al., 2007). (source for a: disaster prevention and preparedness agency (dppa), 2006) mekelle university issn: 2073-073x 39 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 2. geology and aquifer condition of the study area the area consists of three types of rock units, the low-grade metamorphosed proterozoic basement rocks and overlying sedimentary rocks comprising sandstone and tillite of paleozoic age and recent alluvial deposits (fig. 2) (nata et. al., 2007). a brief account of the rock types and the aquifer characteristics is given below. 2.1 geology 2.1.1 basement rocks these are the dominating rock type in the area and their outcrops are found in northern, northeastern, eastern, southeastern, central, southwestern, and northwestern parts of the study area. they occupy both low in the southern parts and high elevated areas in the northern parts and show flat to steep slopes. they cover 22.8% of the area (nata et. al., 2007). the basement rocks are composed of metavolcanics and metasediments. the most conspicuous foliation trend is north-south with deviations to northeast and northwest. apart from foliations, fractures are also present and are irregularly spaced in the rock. in some places they show light to dark grey, light to dark brown and reddish color. dominant minerals present in these low grade greenschist facies rocks include: mafic minerals, chlorite, quartz, feldspars and opaque in metavolcanic rocks and quartz, chlorite, feldspar, muscovite, pyrite, limonite in metasediments (nata et. al., 2007). 2.1.2 sandstone this rock unit accounts for about 8.4% of the total study area (nata et. al., 2007). the outcrops of these rocks are found in the southern and southeastern parts of the study area. they occupy higher elevations in the topography, show steep slopes, cliff forming, and overlie the basement rocks. the rock out crops is very limited as they are covered by alluvium. however, as it was observed from the geological logs of the hand dug wells, it extends from southeast to the central, southwestern, western and northwestern parts of the study area. its maximum thickness which is observed at the southeastern periphery of the watershed is of about 160 meters (nata et. al., 2007). it is composed of white, coarse grained, cross-bedded, calcareous sandstone containing lenses of siltstone, grit and polymict conglomerate with sub-rounded to well-rounded pebbles, cobbles and boulders. clasts of granite, gneisses are scattered erratically and are seen in many places. the lower part of the sandstone is white in color with medium grained angular grains and at places mekelle university issn: 2073-073x 40 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 strongly cemented by clay minerals. upper part is the glacial unit, shows features of a glaciofluvial deposit, angular, poorly sorted grains of quartz and lenses of conglomerate. the rock is porous, highly weathered and show presence of fractures, joints and cross bedding. among structures, joints are prominent and show presence of two sets of joints in sandstone which lies n15ºe and n25ºw (nata et al., 2007). the tillite unit is not found as an outcrop in the study area. however, as it was observed from the lithologs of the hand dug wells, this rock is found underlying the alluvium in the northern, northeastern, eastern, southeastern, southern southwestern parts of the watershed (nata et al., 2007). it is characterized by dark grey color, poorly sorted texture, the presence of big boulder and its unstratified nature. on the basis of the logs of the hand dug wells, its maximum thickness is about 4.5m. the rock is dominated by quartz with limited amount of feldspar and varying amounts of clay, silt and ferruginous and calcareous cementing material (nata et al., 2007). 2.1.3 alluvial deposits in the watershed alluvial deposits are found covering wide area both in the highlands and the lowlands. they are also found as thin strips along the margins of the major rivers and their tributaries. the alluvium is accounting for about 68.8% of the area. the relative abundances and stratigraphic relations of the sediments, however, are generally not uniform through out the watershed. toward the mountains front that is nw and e and topographically high areas in the central parts of the study area, where river gradients are high due to steep slopes, the alluvial sediments, in general, are dominated by sub-angular to sub-rounded coarse grained quartz. in the western parts of the watershed, where the gradient of the rivers decreases down slope, the alluvial deposit is characterized by the presence of medium to fine grained sand with variable content of silt and clay. the maximum thickness of the alluvium is about 3.50 m. 2.2 hydrogeology 2.2.1 aquifer types and characteristics different rock types and unconsolidated sediments which host water and act as aquifers have been classified into two based on the type of porosity and permeability and their extent. 1. localized aquifers with intergranular porosity and permeability (unconsolidated sediments: alluvial sediments along the margins of the major river and its tributaries); and, mekelle university issn: 2073-073x 41 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 2. less extensive aquifers with intergranular and fractured porosity and permeability (consolidated sediments and basement rocks: sandstone, tillite and basement rocks). a brief account of the hydrogeological characteristics of the different rocks and unconsolidated sediments of the watershed is given below with a particular reference to their water storage and transmission capacities (fig. 3) (nata et al., 2008). figure 2. geological and hand dug well location map, debre kidane, eastern tigray .2.1.1 basement rocks impervious, nevertheless local pockets of groundwater reservoir occurs 0 1 kilometer legend sandstone alluvium basement rocks 1535000 1544000 545000 553000 n hand dug well (nata et al., 2007). 2 these rocks are generally in the weathered layer and fracture zones. geological and hydrogeological logs of nine hand dug wells in the western and central parts of the watershed indicate that the weathered and fractured zones are the main sources of groundwater supply in the basement rocks with discharges of hand dug wells range from 0.4 to 1.5 l/s. mekelle university issn: 2073-073x 42 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 2.2.1.2 sandstone terized by highly weathered and fractured nature. these weathered and nt major parts of the area overlying both the basement and sedimentary . methodology hand dug wells that are functional for irrigation purpose was carried out. the rock is charac fractured zones as a whole reaches up to a maximum depth of about 4 m. however, in this rock secondary porosity is significant due to fracturing. fracturing has increased the void space as well as its capacity for water transmission and enhanced its usefulness to the water supply. however, at places it is reduced due to high degree of cementation and in turn permeability and productivity. this rock is considered to host a highly potential aquifer in the flat areas (northern and northeastern parts of the watershed) compared to the steeply to gentle dipping rocks which act as a conduit rather than being an aquifer in the southern and southeastern parts of the area. in the case of tillite presence of considerable amounts of silt and clay as minerals and as ceme reduces the intergranular permeabilities drastically and makes the rock impervious and hamper water movement. at places, however, the fractures provide secondary porosity and permeability and hence make the rock permeable for groundwater flow and storage, 2.2.1.3 alluvial deposits these recent deposits cover rocks. they vary in thickness as well as in composition in the plateau areas and along the margins of the rivers and tributaries. the alluvial deposits mainly comprise of clay, silt, sand and gravel sized particles in different proportion. these deposits have an average thickness 3.50 m. in the western part of the study area, these deposits can be considered as potential water bearing formation due to their primary porosity and location whereas due to their location in the southern parts the alluvium act as a conduit rather than being an aquifer (fig. 3). 3 initially inventory of all during inventory in situ measurement of electrical conductivity, temperature of the groundwater and air temperature for each well were carried out. since the electrical conductivity values were measured in situ at a temperature different from the standard 25 °c, an adjustment of the electrical conductivity values of the water was made by multiplying the respective measured electrical conductivity value by the factor corresponding to the temperature at which the measurement was made. mekelle university issn: 2073-073x 43 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 0 1 kilometer n 1535000 1544000 545000 55300 legend medium productive area poor productive area 0 high productive area figure 3. groundwater potential in the study area (after nata et al., 2008). o determine the number of water samples for chemical analyses stratified and random sampling ochemistry laboratory of applied geology t techniques were utilized. the in situ measured and corrected electrical conductivity values of the groundwater were grouped into different water classes based on quality classification of water for irrigation (wilcox, 1955). then after, 36 water samples were selected randomly from the different water classes for chemical analyses. since majority of the wells in the area are present in the alluvium in the river valley, the wells selected for sampling are also restricted to this part of the area. thirty six water samples each were collected from hand dug wells in both rainy season and irrigation (dry) season. apart from temperature, other physical parameters like turbidity, colure, taste and odor were also measured at each site. for the purpose of chemical analysis the water samples were collected in one liter plastic bottles after thorough wash. all the water sample locations are shown in the figure 2. the water samples were analyzed in the ge department, mekelle university, mekelle. the samples were analyzed for calcium (ca2+), magnesium (mg2+), potassium (k+), sodium (na+), bicarbonate (hco3-), chloride (cl-), sulfate mekelle university issn: 2073-073x 44 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 (so42-), and nitrate (no3-). besides, ph and electrical conductivity in μs/cm at 25 °c were also measured. the cations were analyzed using atomic absorption spectrophotometer and the anions using uv-spectrophotometer (varian spectra, 50b). the data are presented in the form of graphs. piper, stiff and box and whisker diagrams were used for representing and comparing water quality analyses in this study fao (1985 and 1989) guidelines are used to evaluate the suitability of the groundwater of the watershed for irrigation. the guidelines were proposed for evaluating the potential of an irrigation water to create soil or crop problems. various thematic maps such as location, digital terrain model of the watershed, drainage, geological, and hydrogeological were produced by using arcview 3.3 and coreldraw 12 software’s. 4. results 4.1 electrical conductivity, ph and total dissolved solid (tds) ec values were recorded in 36 functional hand dug wells indicate that electrical conductivity values range from 0.05-2.0 dsm-1 with a mean of 0.945 dsm-1. the values measured for 36 groundwater samples vary from 0.27 dsm-1 to 0.96 dsm-1 with an average of 0.53 dsm-1 at 25oc for rainy season. the same during irrigation season range from 0.399 to 1.696 dsm-1 at 25oc with a mean of 0.877 dsm-1 at 25oc. the ec values in groundwater are much higher during irrigation season up to 65% compared to the same of the rainy season (fig. 4). hydrogen ion concentrations (ph) range from 7.70 to 8.60 during rainy season and 7.22 to 8.39 during irrigation season. the average ph value in rainy and irrigation season is 8.12 and 8.01, respectively. total dissolved solid (tds) values in both the seasons for groundwater range from 274.34 to 1092.2 mg/l. in general, tds values for groundwater in both rainy and irrigation seasons are less than 1000 mg/l. 4.2 cations among cations, calcium is the most abundant element and varies from 8 to 60 mg/l during rainy season with a mean concentration of 35.03 mg/l. during irrigation season, the most abundant cation is ca2+ followed by na+, k+ and mg2+. the highest measured calcium concentration is 91 mg/l and the lowest is 30 mg/l, and the mean concentration is 64.92 mg/l. in comparing the mekelle university issn: 2073-073x 45 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 concentration of calcium in the rainy season to that of irrigation season, it is found that the concentration of calcium increased by about 50% in the irrigation season. in the case of magnesium the concentrations during the rainy season range from 6 to 42 mg/l with an average value of 20.15 mg/l. while in dry season the concentrations of magnesium (mg2+) range from 8 to 41 mg/l with an average value of 22.25 mg/l. in general, without exception ca2+ is dominant over mg2+ and magnesium do not show any significant change in concentration. during rainy season na+ values range from 8 to 140 with a mean concentration of 43.33 mg/l (fig.5). in dry season the values range from 18 to 193 with a mean concentration of 54.56 mg/l. in the irrigation (dry) season, the concentration of sodium is increased by about 25% compared to the rainy season. k+ values very low and do not show any variation and hence not considered here. figure 4. ec of groundwater samples in rainfall and irrigation season (rfrainy season; irrirrigation (dry) season). na concntration (mg/l) 0.0 50.0 100.0 150.0 200.0 250.0 w 10 3 w 16 w 39 w 34 w 18 7 w 27 1 w 13 0 w 49 w 15 6 w 22 7 w 16 7 w 26 0 w 32 9 w 23 6 w 31 4 w 15 2 w 31 8 w 11 0 wells code n a( m g/ l) rain season irrigation figure 5. na concentration in the rainy and irrigation seasons. mekelle university issn: 2073-073x 46 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 4.3 anions 4.3.1 bicarbonate (hco-3) and carbonate (co32-) in the study area, carbonate is found mainly in the form of bicarbonates and is the most abundant ion among anions. during rainy season, the concentrations of bicarbonate (hco-3) range from 82.88 to 477.50 mg/l with an average value of 230.28 mg/l. the same during dry season range from 170.80 to 547.00 mg/l with a mean value of 342.38 mg/l. the mean concentration of bicarbonate in irrigation season is increased by about 12% compared to the rainy season. in both seasons the carbonate (co32-) concentrations are very low and all are below 6.7 mg/l. 4.3.2 chloride (cl-) in the study area chloride is the second abundant anion next to bicarbonate. chloride values range from 9.5 to 133.4 mg/l in the rainy season with a mean concentration of 50.71 mg/l. in the irrigation season, the concentrations of chloride (cl-) range from 6.5 to 156.1 mg/l with an average value of 45.41 mg/l. chloride ion do not show any significant seasonal variation (fig. 6). chloride concntration 0 20 40 60 80 100 120 140 160 180 w 10 3 w 16 w 39 w 34 w 18 7 w 27 1 w 13 0 w 49 w 15 6 w 22 7 w 16 7 w 26 0 w 32 9 w 23 6 w 31 4 w 15 2 w 31 8 w 11 0 wells code c l ( m g/ l ) water (rf) water(irr) figure 6. chloride ion concentration in the rainy and irrigation seasons (rfrainy season; irrirrigation (dry) season)). 4.3.3 sulphate (so4-2) sulphate is the third most abundant anion next to bicarbonate and chloride in the study area. the values range from 7.2 to 51.80 mg/l in the rainy season with a mean concentration of 25.03 mg/l. in the irrigation season, the concentrations of sulphate (so42-) range from 15.12 to 86.09 mg/l with an average value of 36.35 mg/l. mekelle university issn: 2073-073x 47 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 4.3.4 nitrate (no3-) the measured nitrate concentrations range from 0.5 to 43.9 mg/l in the rainy season with a mean concentration of 9.74 mg/l and range from 3.00 to 57.98 mg/l for dry season with an average value of 16.47 mg/l (fig.7). figure 7. nitrate values in water from hand dug wells (rfrainy season; irrdry season). 4.4 water type to understand the chemical type of water, different diagrams such as piper, stiff, and box and whisker diagrams were used to plot the data. the purpose of plotting data in various diagrams is to see how much effective they are for irrigation data and what additional information they provide compared to piper diagram. before plotting the proportions of both the anions and cations they were converted from ppm to epm. samples collected in both rainy and irrigation season were plotted in these piper, stiff and box and whisker diagrams. they are shown in figure 8 (piper); figure 9 (stiff) and figure 10 (box and whisker). according to these plots groundwater type in the study area varies from mg-hco3, ca-hco3, mg-cl, na-hco3 to khco3 type. during rainy season, the dominant water type is ca-hco3 and is indicated by 42% of the samples, followed by mghco3 by 30%, nahco3 by 22%, mg-cl by 3% and k-hco3 by 3% samples. in irrigation season the ca-hco3 is the dominant type indicated by 69% of the samples and is followed by na-hco3 type by 24% and mghco3 type by 7% samples. interestingly, piper diagram shows hco3 and mixed cation type for rainy season and ca-nahco3 type for dry season. whereas stiff diagram shows ca-hco3 type for rainy season and nahco3 for dry season and box and whisker plot indicates ca-hco3 type for both the seasons. mekelle university issn: 2073-073x 48 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 figure 8. piper diagram for the water samples a. rainy and b. irrigation season. figure 9. stiff diagrams (a) ca -hco3 water type and (b) na-ca-mg-hco3-cl type. figure 10. box and whisker plot for water samples, (a) rainy and (b) irrigation season. mekelle university issn: 2073-073x 49 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 4.5 sodium absorption ratio (sar) sar (todd, 1980) was calculated using aqua chem 4.0 software. the values range from 0.35 to 6.51 with an average value of 1.51 for rainy season. the mean, minimum and maximum sar during the irrigation season is 1.44, 0.49 and 5.63, respectively. 5. discussion 5.1 physical and chemical characteristics groundwater being subsurface water derives its contents from different sources like soil, weathered rock, fresh rock and fertilizer with which it will be in contact during infiltration or percolation. this will be aided by the climate (ex. temperature); co2 either free or dissolved state in soil and time duration. variations in the content of groundwater often associated with irrigation practices, temperature, co2 and time as the main lithological source generally remain constant. such changes are prominent during rainy and dry seasons where both quality and quantity will be affected. during rainy season supply of water being more its ability to carry suspended material will be more compared to ions due to limited amount time duration. the data collected on color, taste etc in the field, shows that about 12% of the samples are muddy or turbid in rainy season with red/brownish color due to the presence excessive amount of suspended matter. whereas it was found that the water was transparent in dry season. regarding other parameters, there was no problem of odder or taste or aroma in samples in both the seasons. furthermore, a major part of the water in rainy season leaves the catchment as run off and the remaining part will percolate through irrigated soil, alluvial cover and weathered rock to recharge groundwater. so the shallow hand dug wells get recharge prominently from two different routes, 1) drainage channels with sand dominated channel sediments, and 2) irrigated soil, non-irrigated soil and weathered rock. thus sheet flow and stream water supply dominate rainy season while soil infiltration during dry season. this is well reflected in the compositional variations observed in the water samples collected during rainy and dry seasons. such as ca, hco3, no3 and so4 are dominant in the dry compared to the rainy season. the reason for such variations is partly natural and partly anthropogenic. ec, ph and tds data suggest though shows variation in their values the majority of the values lie within the acceptable range for irrigation purpose (fao, 1989). according to fao (1989) mekelle university issn: 2073-073x 50 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 irrigation water quality guidelines, normal ph range is 6.5 to 8.4. out of the total analyzed groundwater samples in both sampling seasons, 97% of them are within this normal range. in the case of carbonate and bicarbonate ions, which are derived from the dissolution of carbonate minerals and available carbonic acid in the soil horizons, are within the acceptable range according to fao (1985) water quality guidelines for irrigation purpose. the acceptable range for bicarbonate acceptable range is 1-10 meq/l for bicarbonate and 0-0.1 meq/l for carbonate. therefore, the groundwater of the watershed has no restriction in use for irrigation purposes. chloride values being <4 meq/l in the samples collected in rainy season and also the same values in all the samples except one for dry season indicating that if the groundwater of the watershed is considered for surface irrigation use, no chloride toxicity will rise. however, a groundwater from one well needs slight to moderate restriction on use. according to fao (1985), water with a sulphate concentration of 0-20 meq/l is considered as a usual range in irrigation water. in the study area, the concentration is not above 1.0 meq/liter. therefore, it is recommended for use for irrigation purpose without restriction. unlike most other elements in groundwater, nitrate is not derived primarily from the minerals (rocks) that make up the groundwater reservoir. instead, nitrate enters groundwater as part of nitrogen cycle in the earth’s hydrosphere and biosphere. in groundwater natural nitrate concentrations generally range from 0.1 to 10 mg/l (davis and dewiest, 1966). nitrate nitrogen (no3 – n) content greater than 30 mg/l is considered harmful and is severely restricted to use for irrigation purposes (fao, 1989). out of the total analyzed groundwater samples (fig. 8), 31% in rainy season and 3% in irrigation season have a concentration of nitrate nitrogen (no3 – n) below 5 mg/l. groundwater from these wells is not hazardous and needs no restriction on use (fao, 1989). 3% in rainy season and 8% in irrigation season have a concentration of nitrate nitrogen (no3 – n) greater than 30 mg/l. groundwater from these wells is hazardous and needs severe restriction on use. in the remaining 66% in rainy season and 89 % in irrigation season, the groundwater of the watershed have a concentration of nitrate nitrogen (no3 – n) between 5 and 30 mg/l. groundwater from these wells needs slight to moderate degree of restriction on use. the source for this ion seems to be anthropogenic. in the case of ca, mg and na the concentration being in the range of 0-20 meq/l for ca2+, 0-5 meq/l for mg2+ and 18-193 ppm for na. these values though are within the acceptable range for mekelle university issn: 2073-073x 51 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 irrigation (fao, 1985) purpose, some of the samples showing higher values for na in dry season which is well reflected in the stiff diagram (fig. 9), seems is an indicator towards increasing na with time and in turn sar. sodium ion is mainly derived from the breakdown of silicate minerals particularly feldspars (albite) and generally get mobilized in water in dissolved state and hence will be lower its content in the stream and shallow hand dug well as well in the rainy season. it is also well reflected in its concentrations during rainy season. but during irrigation (dry) season the values are higher because the well gets its recharge mainly from the soil and rock sources in addition from drainage channels. the reason for such increase of na content may be because 1) it gets more time to interact with the source material soil and rock; 2) the irrigated soil is becoming sodium-rich gradually due to its absorption replacing ca; 3) availability of more minerals in the weathered front and alluvium for interaction and dissolution. though the reasons are common for other cations as well in the case of na, absorption process seems to be prominent. 5.2 salinity hazard in the rainy season, out of the analyzed thirty six groundwater samples, twenty eight samples have an electrical conductivity values below 0.7 ds/m and the remaining eight samples have an electrical conductivity ranging from 0.72 to 0.96 ds/m (fig. 4). in irrigation (dry) season, out of the analyzed thirty six groundwater samples, eleven samples have an electrical conductivity values below 0.7 ds/m and the remaining twenty five samples have a range from 0.71 to 1.70 ds/m. therefore, based on electrical conductivity values, two types of groundwater are recognized in the study areagroundwater which is not hazardous and needs no restriction on use and groundwater which needs slight to moderate degree of restriction on use. the first type groundwater can be used for irrigation for almost all crops and for almost all kinds of soils. no soil or cropping problems will rise. very little salinity may develop which may require slight leaching; but it is permissible under normal irrigation practices except in soils of extremely low permeabilities. to achieve a full yield potential using the second type, gradually increasing care in selection of crop and management alternatives are required. 5.3 water infiltration rate (sodicity) an infiltration problem related to water quality occurs when the normal infiltration rate for the applied water or rainfall is appreciably reduced and water remains on the soil surface too long or infiltrates too slowly to supply the crop with sufficient water to maintain acceptable yields. mekelle university issn: 2073-073x 52 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 although the infiltration rate of water into soil varies widely and can be greatly influenced by the quality of the irrigation water, soil factors such as structure, degree of compaction, organic matter content and chemical make-up can also greatly influence the intake rate. the two most common water quality factors which influence the normal infiltration rate are the salinity of the water and its sodium content relative to the calcium and magnesium content. high salinity water will increase infiltration. low salinity water or water with high sodium to calcium and magnesium ratio will decrease infiltration. both factors may operate at the same time. the infiltration rate generally increases with increasing salinity and decreases with either decreasing salinity or increasing sodium content relative to calcium and magnesium the sodium adsorption ratio (sar). therefore, the two factors, salinity and sar provide information on its ultimate effect on water infiltration rate. 5.3.1 rainy season out of the analyzed thirty six groundwater samples, 1) five samples show sar values between 3 and 6 and electrical conductivity between 1.2 and 0.3 ds/m at 25 ºc; 2) twenty three samples have a computed sar ranging from 0 to 3 and an electrical conductivity value ranging from 0. 7 to 0.2 ds/m at 25 ºc; and 3) seven samples have a computed sar values ranging from 0 3 and a corresponding electrical conductivity greater than 0.7 ds/m at 25 ºc. in this season in general two types of water are recognized: groundwater which needs slight to moderate degree of restriction on use (i.e., groundwater from both the five and twenty three samples) and a groundwater which is not hazardous and needs no restriction on use, which is a groundwater from the last seven samples (fao, 1989). 5.3.2 irrigation season out of the analyzed thirty six groundwater samples, 1) eleven samples have sar values ranging from 3 to 6. however, these eleven samples are classified in to two groups based on their respective electrical conductivity values. of the eleven samples two of them have an electrical conductivity greater than 1.2 dsm-1 at 25 ºc, indicating no restriction on use and in the nine samples their respective electrical conductivity values are in the range of 1.2-0.3 dsm-1 at 25 ºc, indicating that the groundwater from these hand dug wells needs slight to moderate restriction on use; 2) the remaining twenty five samples have a computed sar values ranging from 0 to 3. however, these twenty five samples are classified in to two groups based on their respective electrical conductivity values. out of the twenty five samples, eighteen samples have an mekelle university issn: 2073-073x 53 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 electrical conductivity value greater than 0.7 dsm-1 at 25 ºc, indicating no restriction in using this water, and the remaining seven samples have an electrical conductivity value ranging from 0.7 to 0.2 dsm-1 at 25 ºc, indicating that the water needs slight to moderate degree of restriction on use. in addition, wilcox diagram (wilcox, 1955) was also used to evaluate the potential of the groundwater to create hazard of salinity and sodicity. accordingly, three classes of water are recognized in the rainy season: s1-c1 (low sodium/alkali and low salinity hazards), s1-c2 (low sodium/alkali and medium salinity hazards) and s1-c3 (low sodium /alkali and high salinity hazards). as shown in figure 11, out of the analyzed samples 14% of them are in the class of s1c1 (low sodium /alkali and low salinity hazards), 80% in the class of s1-c2 (low sodium /alkali and medium salinity hazards) and the remaining 6% in s1-c3 (low sodium /alkali and high salinity hazards). in the irrigation season two classes of water are recognized: s1-c2 and s1-c3. as shown in figure 12, out of the analyzed samples 30 % of them are in the class of s1-c2 and the remaining 70 % are in the class of s1-c3. figure 11. irrigation water classes using wilcox diagram (rainy season). mekelle university issn: 2073-073x 54 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 sample data figure 12. irrigation water classes using wilcox diagram (irrigation season). 5.4 toxicity problems 5.4.1 rainy season with the exception of five samples, in all the remaining thirty one samples the sar values are well below 3, indicating no sodium toxicity will rise by using the groundwater from these hand dug wells for surface irrigation (fao, 1989). in the five samples the sar values lie within the range from 3 to 9, suggesting the necessity of slight to moderate degree of restriction on use of the groundwater from these five hand dug wells for surface irrigation. the likelihood of sodium toxicity hazards is high if the groundwater from these five hand dug wells is considered for use. in the case of sar, the values below 9 indicate low or little danger for sodium and use on sodium sensitive crops must be cautioned; between 10 and 17 medium hazard; 18 and 25 highly hazard and above ≥ 26 very high hazard (grattan, 2002). 5.4.2 irrigation season out of the analyzed thirty six groundwater samples, in the twenty five samples the sar values are well below 3, indicating no sodium toxicity will rise by using the groundwater from these hand dug wells for surface irrigation (fao, 1989). in the remaining eleven samples the computed sar values lay within the range from 3 to 9, suggesting the necessity of slight to moderate degree of restriction on use of the groundwater from these eleven hand dug wells for mekelle university issn: 2073-073x 55 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 surface irrigation. the likelihood of sodium toxicity hazards is high if the groundwater from these eleven hand dug wells is considered for use. 5.5 water classes the suitability of the groundwater for irrigation is also examined based on wilcox (1955) classification scheme. accordingly, in the rainy season the groundwater is categorized into two groups: good and permissible. out of the total analyzed samples, 89% of the groundwater is in good class and the remaining 11% is in permissible class. in the irrigation season, out of the total analyzed samples, 30% of them are in good class and 70% is in the permissible class. table 1. quality classification of water for irrigation (irrigation season) (after wilcox, 1955). ec (ds/m) mean stdev no. wells water class (todd, 1980) degree of restriction (fao, 1985) % 0.25-0.75 0.59 0.11 11 class 2, good none 30% 0.75-2.00 0.99 0.22 25 class 3, permissible slight moderate 70% the data generated in this study are limited. the effect of lithologies on the chemistry of water and also seasonal variation could not be understood because of non-exposure of the rock and the wells studied are mainly confined to very shallow hand dug wells not deeper wells. so the data is discussed mainly in terms of its suitability for irrigation purposes and possible toxic effects if any. 6. conclusions in general, in most part of the study area the groundwater quality is suitable for irrigation. if the groundwater is considered for irrigation use, no serious soil or cropping problems will arise. in few areas, however, the groundwater needs slight to moderate degree of restriction on use. in these areas farmers has to be advised on how they should manage and utilize the groundwater for their irrigation activities. gradual increase of na due to absorption may cause sodicity problem hence necessary measures are to be taken to control it. to maximize the opportunity of the utilization hand dug wells for irrigation, the following recommendations are suggested: mekelle university issn: 2073-073x 56 nata et al., (mejs) volume 1 (1): 36 – 58, 2009 ● detail groundwater potential of the watershed should be investigated to overcome the overexploitation of groundwater and to know the maximum limit of abstraction; ● soil quality analysis should be conducted to see the effect of groundwater utilization for irrigation on soil quality; ● recharging measures should be given due attention by the community to maintain and maximize the discharge; and, ● impact assessment study is suggested to see the significance of hand dug wells utilization on livelihoods of the households. 7. acknowledgements we thank the department of earth sciences, mekelle university, for providing geochemistry laboratory facilities to carry out the water analysis work. thanks are also due to all those friends who helped during field and lab work and for going through the manuscript many times and providing many constructive criticisms. 8. references bohn, h. l., brain, l. m., george, a. & o’connor. 1985. soil chemistry, second edition. john wiley & sons, new york, pp. 234-248. brady, n. c. 2002. the nature and properties of soil, upper addle river, 13th edition. macmillan, new jersey, pp. 413-436. davis, s.n. & dewiest, r. j. m. 1966. hydrogeology. john wiley & sons, new york, pp. 463. fao. 1985. water quality for agriculture. food and agricultural organization (fao) of the united nations. fao, irrigation and drainage paper, no.29, rome. fao. 1989. water quality for agriculture. fao, rome, pp. 163. grattan, s. r. 2002. irrigation water salinity and crop production. university of california. (http://www.avocadosource.com/links/ salinity/grattanstephen2002_abs.htm -7k –) (accessed on august 12, 2005). mekuria tafesse. 2003. small-scale irrigation for food security in sub-saharan africa. report and recommendations of a cta study visit ethiopia, 20–29 january 2003, cta working document number 8031, the acp-eu technical centre for agricultural and rural cooperation (cta), the netherlands. mekelle university issn: 2073-073x 57 http://www.avocadosource.com/ nata et al., (mejs) volume 1 (1): 36 – 58, 2009 ministry of water resources. 2002. water sector development program 2002-2016 report. the federal democratic republic of ethiopia, ministry of water resources, addis ababa, ethiopia. nata tadesse. 2003. hydrogeological investigation and environmentally sound plans for the development of groundwater in the weri river basin, tigray, ethiopia. ph.d. thesis, institute of applied geology, university of natural resources and applied life sciences (boku), vienna (unpubl.). nata tadesse, ahmed mohammed & essayas tsegaye. 2007. comparison on aquifer characterization of abrha-weatsbha area and debre kidane watershed, tigray. report, department of applied geology, mekelle university, mekelle (unpubl.). nata tadesse, asmelash berhane & bheemalingeswara, k. 2008. initiatives, opportunities and challenges in shallow groundwater utilization: a case study from debrekidane watershed, hawzien woreda, tigray region, northern ethiopia. agricultural engineering international: the cigr ejournal. manuscript lw 08 008, vol. x, p. 22. rosegrant, m.w. & clauidi ringler. 1999. impact food security and rural development of reallocating water from agriculture, environment and production technology division, international food policy research institute (ifpri); eptd discussion paper, no.47, usa. todd, d. k. 1980. groundwater hydrology. john wiley & sons, new york, pp. 525. wilcox, l. v. 1955. classification and use of irrigation waters, u.s. dept. agric. circ. 969, washington, d.c., pp. 19. mekelle university issn: 2073-073x 58 research article http://dx.doi.org/10.4314/mejs.v10i1.7 momona ethiopian journal of science (mejs), v10(1):89-108, 2018 ©cncs, mekelle university, issn:2220-184x submitted on: 09-01-2018 accepted on: 16-03-2018 indirect estimation of selected measures of fertility and marital fertility from information on cwr (0-9): an application to india /states /districts krishna murthy ponnapalli1* and ravi kant soren2 1institute of population studies (ipost), mekelle university, p.o.box 231, mekelle, ethiopia (*pkmurthy2001@yahoo.com). 2international institute for population studies (iips), deonar, mumbai-400 088, india. abstract fertility is one of the important components of population change, the other two being mortality and migration. when vital statistical data on number of births is readily available it is estimated directly using various direct measures of fertility such as the crude birth rate (cbr). when the information on number of births is not directly available, fertility is measured using the census information on child woman ratios (cwr) of various types. cwr has several limitations, but gained importance with the attempts made by rele in 1963, and followed by several other researchers such as hauer and his co-authors in 2013 deriving tfr from it. in the present study yet another attempt is made to use cwrs to derive not only tfr but also other summary indicators such as the tmfr. a set of simple mathematical formula have been used to estimate the fertility and marital fertility using the cwr of the ages 0-9. the 2011 census age-sex data of districts in india was used to derive a set of fertility estimates for total, rural and urban areas of all districts. further, these estimates of 2011 have been compared with the estimates of 2011 earlier made by guilmoto and rajan to analyse the robustness of the estimates. keywords: fertility, child women ratio, indirect estimation, age-sex data, tfr, tmfr, india. 1. introduction the commonly used measures such as rates, ratios, percentages and probabilities in mathematics and statistics also play a great role in understanding various demographic phenomenon’s such as fertility. fertility is one of the important components of population change, the other two being mortality and migration. when vital statistical data on number of births is readily available it is estimated directly using various direct measures of fertility such as the crude birth rate (cbr). when the information on number of births not directly available fertility is measured using the census information on child woman ratios (cwr) of various types. cwr has its own merits and demerits. when using the child woman ratio (children 0-4/ women 15-49) as an indicator of fertility we assume that children enumerated by the time of the census in the age group 0-4 are the actual number of children born 5 years ago and those surviving. the logic behind is that it is assumed that mortality is negligible on the children 0-4 and the women 15-49, and also assume that no migration during the last five years of the census enumeration date; then the children 0-4 http://dx.doi.org/10.4314/mejs.v10i1.7 mailto:pkmurthy2001@yahoo.com krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 90 issn: 2220-184x enumerated at the census date equals to those born 5 years ago and surviving till today and thus, nothing but the number of births taken place during the past five years. when a child women ratio is constructed using this data then the cwr0-4 refers to 2.5 years before the census date as c0-4 here refers to the average number of births during the five year period before the census. if there is considerable amount of the impact of mortality and migration on the child women ratio, one has to adjust the measure for the above. experience shows that one may use the child women ratio as a rough indicator of fertility without much problem, assuming a negligible impact of mortality and migration. rele (1976, 1987) suggested use of various types of child woman ratios (cwrs) to estimate more sophisticated indicators such as tfr and grr indirectly. recently, hauer et al. (2013) suggested another simple method to estimate tfr from the information on cwr. when the infant mortality is comparatively insignificant, and also no migration among the women and dependent children the method suggested by them is observed to give plausible estimates of tfr. smith (1992) suggested various measures of fertility simply by means of exploiting the interrelationships existing among different measures. inspired by the above works namely by hauer et al. (2013); smith (1992); and rele (1976, 1987), this paper makes an attempt to suggest a new methodology which does not require serious assumptions, not much input data but gives robust estimates of various measures of fertility even for sub-national populations in the absence of essential information on number of births but just by using the cwrs. the data required for estimation of various measures of fertility and mortality is traditionally collected from three important sources namely: censuses, civil registration system, special surveys such as sample registration system (srs) in india. all the above three sources have their own merits and demerits. census and special surveys provide the information on children and women also and so following rele (1976) one may compute a variety of child women ratios as per the need such as cwr0-4(c0-4/w15-49), cwr5-9(c5-9/w20-54), cwr0-9(c0-9/w15-54), where c stands for children, w stands for women. the advantage of this method is that it is possible to derive fertility measures even for the smallest area like village as cwr available at the local level. growing importance for decentralized planning in india and other countries over time made the governments and many a researcher to search for alternative ways of obtaining reliable estimates of fertility and mortality at below state level units such as districts, natural regions of a state, krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 91 issn: 2220-184x selected cities, etc. recent special surveys of india namely national family health survey (nfhs), district level household survey (dlhs), annual health survey (ahs) and others are best examples for such an alternative ways. like the traditional sources, the above alternative sources of information also have their merits and demerits. indirect estimation of fertility and mortality using different alternative data sources, alternative methodologies and mixed methods/data sources thus started playing an important role in many of both developed and developing countries. a review of existing literature on indirect estimation of fertility and mortality carried out by several scholars in india and abroad clearly indicates that there is still a need for the development of new procedures and use of new data sources: (1) for a better understanding of the fertility and mortality processes at sub-state level units such as districts in india, (2) for a better evaluation of data gathered on fertility and mortality from various newly developed data sources such as srs, nfhs, dlhs, etc., (3) for better assisting the various governments in their needs for the decentralized planning and policy implementation. however, most of the sophisticated indirect techniques suggested so far require stringent assumptions, huge amount of input data and thus make them not much applicable to derive estimates for below the state level such as the districts, towns, villages in india. further, to the knowledge of the present researchers (1) no researcher tried to make use of the marital status distribution data of india especially of the 2011 census in deriving indirectly the fertility measures like cbr, tfr, gmfr and tmfr (2) no attempt was made by any researcher to provide the above indirect estimates for the rural and urban areas of various districts. thus the present study aims (1) to provide a new, simple and also innovative thought provoking approach for the derivation of various fertility measures/formulae which no one tried before; (2) to make use of the marital status distribution of age-sex data of 2011 census data to derive a new set of fertility indicators for districts in india. to be specific, the objectives of this study are (1) to develop a simple indirect technique for estimating cbr, tfr and tmfr and other related fertility measures from the information on the age-sex and marital status distribution of the population; (2) to derive plausible estimates of the above measures for districts/states/uts in india using 2011 census age-sex marital status distribution data; and (3) to provide above estimates even for rural and urban areas of all districts in india. in the following sections the paper presents the details of the data sources, methodological details and analysis of the results. krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 92 issn: 2220-184x 2. data and methodology 2.1. data the data required for the present study on children of ages 0-9 years and women (or females) of ages 15 to 54 years, is collected from the marital status data by age-sex distribution of the 2011 census of the registrar general of indi (rgi). soft copy of the 2011 census age-sex marital status distribution of data of various states/uts/districts in india was downloaded from the site http://www.censusindia.go.in. the quality of age-sex data of 2011 census seems to be good and has been improved over the period due to increasing literacy among women and a great exposure to mass media such as televisions, mobiles, etc. 2.2. methodology the methodology suggested in this study is explained as below: in simple terms, to derive various fertility measures indirectly let us define at first that c0-9 = child population of ages 0 to 9 tp = total population of both sexes tfp15-54 = total female population of the ages 15 to 54 mfp15-54 = married female population of ages 15-54 cbr = crude birth rate gfr = general fertility rate tfr = total fertility rate grr = gross reproduction rate gmfr = general marital fertility rate tmfr = total marital fertility rate then, one can derive various fertility measures indirectly using the following formulae: cbr = ((c0-9/10)/tp) x 1000 gfr = ((c0-9/10)/tfp15-54) x 1000 tfr = (gfr/1000) x 35 grr = tfr x (1/(1+ srb)) = (tfr/2.05) ; srb = sex ratio at birth gmfr = ((c0-9/10)/mfp15-54) x 1000 tmfr = (gmfr/1000) x 40 the present methodology involved using various types of child/women or child/population ratios. the results obtained using the above formulae may be affected by some of the assumptions made by the researchers. http://www.censusindia.go.in/ krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 93 issn: 2220-184x in the above formulae of cbr, 10 represents the number of years and refer to the fact that children of ages 0 to 9 years were born 10 years before the census date. following hauer et al. (2013) dividing c0-9 by 10 leads to an indirect estimate of the number of births, assuming that the impact of mortality and migration is very negligible. similar is the explanation in case of other measures. gfr is normally derived using tfp aged 15-49. here in deriving gfr we considered tfp15-54, as its numerator consists of c0-9 and taking tfp15-54 is meaningful. the formula given here for grr calculation is generally considered as an indirect estimation procedure. this approach is mostly used by demographers as normally this formula also lead to a good estimate of grr. in the grr formulae, the factor 2.05 is obtained by considering 105 male births for 100 female births. when sex ratio at birth is available one may us the actual sex ratios at birth. but the above assumption of 1.05 srb is acceptable in general. following smith (1992) it is also suggested here to use the figures 35 and 40 in the formulae of tfr and tmfr respectively; and they are merely the assumed values of the reproductive life time of a typical woman of any developing country such as india. one may use in fact 35 in case of tmfr also (instead of 40) but on the safer side it is assumed here that the currently married women on an average may take some more time than the other in completing their fertility time period, especially in the developing countries of asia and africa. all the fertility estimates provided here for districts in india were derived using the 2011 census data, however refer to the year 2006.5 or approximately the year 2007. because as a matter of fact all the fertility estimates we derive using children 0-9 that refer to the births centered between 0-9 years before the census date. it is assumed that the input data was not affected (or affected negligibly) by infant mortality and migration factors in the previous 10 years. this assumption we may make to be realized sometimes may not be applicable to areas such as jammu and kashmir where continuous disturbances are existing and the input data also affected. so, one should be cautious while interpreting the results for such areas as jk and its sub-regions. 3. results and discussion 3.1. testing the validity of the estimates validity of the derived estimates of cbr and tfr is made by comparing them with that of the indirect estimates of cbr and tfr earlier derived by guilmoto and rajan (2013). guilmoto and krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 94 issn: 2220-184x rajan (2013) used a modified version of the reverse survival method (mrsm) earlier suggested by bhat (1996). figure 1. comparison of estimates of cbr from mrsm with the present procedure. figure 2. comparison of the estimates of tfr from mrsm using the present procedure. krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 95 issn: 2220-184x comparison of the regression lines fitted between tfr and cbr made by the two indirect estimation procedures (see figs 1 and 2) clearly indicates that cbr and tfr estimates derived by using the present methodology are quite comparable. the percent variation explained by the simple linear regression model i.e., r2 is observed to be very high (0.96) in both cases. thus, other derived measures may also be considered acceptable for all practical purposes. appendix (table 1) provides cbr, tfr and tmfr estimates indirectly derived by the present methodology for the total, rural and urban of all india, states and districts for the time period 2007 derived using the cwr(0-9) values of the 2011 census. tfr and cbr values used in the figures 1 and 2 are taken from the same table. 3.2. analysis of the results for convenience state level estimates were provided graphically in figures 3, 4 and 5 for the indicators of cbr (per 1000 population), tfr (per woman) and tmfr (per woman) for total, rural and urban areas. results in the diagrams are as expected and are self-explanatory. figure 3. indirect estimates of cbr india and selected states-2007. figure 4. indirect estimates of tfr -india and selected states-2007. krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 96 issn: 2220-184x figure 5. indirect estimates of tmfr -india and selected states-2007. important conclusions that we may arrive at are: (1) whatever indicator you may consider, urban fertility is always observed to be less than the rural fertility. interestingly, in case of kerala for both rural and urban areas fertility remain to be the same due to obvious reasons. (2) states of north india especially bihar, jharkhand, madhya pradesh, rajasthan and uttar pradesh always showed high fertility when compared to other states in india, irrespective of the fertility indicator you may consider. 3) a special mention has to be made here in case of the state of jammu and kashmir (jk). guilmoto and rajan (2013) also obtained almost similar results as observed here. while interpreting the result for jk the above authors pointed out that the reported age distribution of jk is not acceptable for fertility estimation due to obvious reason of low data quality. thus to state, jk results at the state and district level provided here may also be accepted with a caution. 4. conclusion this study suggested a new and innovative methodology to estimate tfr and related measures using a simple ratio that is child women ratio of ages 0-9. using the age-sex marital status distribution of india data of 2011 census it provided the tfr, tmfr and related indirect estimates for india / states /uts /districts. various estimates obviously refer to the year 2007, instead 2011 census year. a comparison of the estimates arrived at here, with that of guilmoto and rajan (2013) estimates of cbr and tfr derived using the 2011 age-sex distribution data indicates that they are quite comparable. as expected, urban fertility is observed to be lower than krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 97 issn: 2220-184x the rural fertility, among all districts in india. it is to conclude that the simple and innovative indirect method suggested here even it depends on few meaningful assumptions, may succeed in providing plausible estimates even for sub-state units, rural-urban regions, and religious groups, etc. if data permits. thus the simple methodology presented here which use a simple ratio has wide implications and seems to be experimented further for its proper use and importance. the present methodology may be applicable to other developing countries in the world like that of ethiopia, if (1) data permits and (2) the assumptions made also acceptable to some extent. the present method firstly allows estimation of fertility indicators even for the smallest units of analysis, secondly allows to test the accuracy of estimates arrived at by other methodologies, and thus seems to serve as a useful indirect technique for fertility analysis. 5. acknowledgements the authors are thankful to the anonymous reviewers for their constructive comments. 6. reference bhat, p. n. m. 1996. contours of fertility decline in india: a district level study based on the 1991 census. in: k. srinivasan (ed.) population policy and reproductive health, new delhi: hindustan publishing corporation, isbn -10: 8170750423, pp.96-179. guilmoto, c. z. & rajan, s. i. 2013. fertility at the district level in india: lessons from the 2011 census, economic and political weekly, epw vol. xlviii no. 23(8):59-70 and appendix tables on cbr and tfr. hauer, m., baker, j & brown, w. 2013. indirect estimates of total fertility rate using child woman/ratio: a comparison with the bogue-palmore method. plos one, 8(6):1-7, e67226 (from www.plosone.org). rele, j.r. 1976. fertility analysis through extension of stable population concepts. westport, connecticut: greenwood press. (originally published in 1967 by international population and urban research, university of california, berkeley) rele, j.r. 1987. fertility levels and trends in india, 1951-81. population and development review, 13(3): 513-530. smith, d. p. 1992. formal demography. plenum press, isbn: 978-0-306-43869-1, ebook isbn: 978-1-4899-2465-0, pp.228-234. https://www.tib.eu/en/search/?tx_tibsearch_search%5bquery%5d=isbn%3a%288170750423%29 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 98 issn: 2220-184x appendix table 1 : indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr india (in) 19.8 2.5 3.9 21.2 2.8 4.2 16.7 2.0 3.1 jammu & kashmir (jk) 22.5 3.0 5.3 24.4 3.3 5.8 17.5 2.2 4.1 kupwara (jk) 30.0 4.9 9.3 30.5 4.9 9.2 26.5 5.0 9.6 badgam (jk) 28.4 4.1 8.2 29.5 4.3 8.7 20.7 2.9 5.6 leh(ladakh)(jk) 12.9 1.8 3.5 14.7 1.9 3.7 9.6 1.6 3.0 kargil (jk) 20.1 2.7 5.3 20.9 2.8 5.4 14.1 2.0 4.1 punch (jk) 24.8 3.5 5.6 25.5 3.6 5.7 16.8 2.3 4.0 rajouri (jk) 23.7 3.3 5.2 24.6 3.4 5.3 13.5 2.2 3.7 kathua (jk) 19.8 2.5 4.0 20.4 2.6 4.1 15.8 1.9 3.1 baramula (jk) 22.9 3.1 5.9 24.1 3.3 6.3 17.1 2.3 4.4 bandipore (jk) 22.7 3.1 6.0 23.7 3.2 6.3 17.7 2.2 4.5 srinagar (jk) 17.8 2.1 4.2 20.0 2.4 4.6 17.8 2.1 4.2 ganderbal (jk) 24.2 3.4 6.3 24.2 3.4 6.3 24.2 3.3 6.1 pulwama (jk) 22.8 2.9 5.6 22.9 2.9 5.6 21.9 3.0 6.0 shupiyan (jk) 22.1 2.8 5.2 22.4 2.8 5.2 16.7 2.2 4.3 anantnag (jk) 26.6 3.7 7.0 27.8 3.9 7.4 23.2 3.0 6.1 kulgam (jk) 23.1 2.9 5.5 23.8 3.1 5.7 19.9 2.5 4.6 doda (jk) 24.3 3.3 5.3 24.9 3.4 5.5 18.1 2.4 4.1 ramban (jk) 26.9 3.9 6.2 27.4 4.0 6.3 15.9 2.1 3.6 kishtwar (jk) 24.2 3.3 5.5 24.8 3.4 5.6 16.0 2.0 3.8 udhampur (jk) 21.7 2.9 4.4 23.3 3.1 4.7 14.9 2.0 3.2 reasi (jk) 24.9 3.5 5.6 25.6 3.7 5.7 17.6 2.2 3.7 jammu (jk) 15.9 1.9 3.1 17.8 2.1 3.5 14.0 1.7 2.7 samba (jk) 17.6 2.1 3.4 18.0 2.2 3.5 15.8 1.9 3.2 himachal pradesh (hp) 16.6 1.9 3.1 16.8 2.0 3.1 14.2 1.6 2.7 chamba (hp) 19.7 2.4 3.9 20.1 2.4 4.0 14.3 1.7 3.0 kangra (hp) 15.9 1.8 2.9 16.0 1.8 2.9 14.2 1.6 2.8 lahul & spiti (hp) 14.6 1.8 3.3 14.6 1.8 3.3 na na na kullu (hp) 16.8 2.0 3.2 17.0 2.0 3.2 14.5 1.7 2.7 mandi (hp) 16.5 1.9 2.9 16.7 1.9 2.9 13.3 1.5 2.4 hamirpur (hp) 15.7 1.8 2.7 15.8 1.8 2.7 13.8 1.5 2.5 una (hp) 16.6 2.0 3.2 16.7 2.0 3.2 15.8 1.9 3.1 bilaspur (hp) 15.8 1.9 2.9 15.9 1.9 2.9 14.7 1.7 2.7 solan (hp) 17.0 2.1 3.2 17.3 2.1 3.2 15.5 2.0 3.1 sirmaur (hp) 19.1 2.4 3.9 19.5 2.4 4.0 15.9 1.8 3.0 shimla (hp) 14.9 1.7 2.8 15.6 1.8 2.9 12.9 1.4 2.5 kinnaur (hp) 14.4 1.9 3.1 14.4 1.9 3.1 na na na punjab (pb) 16.2 2.0 3.2 16.5 2.0 3.3 15.8 1.9 3.0 gurdaspur (pb) 16.3 2.0 3.3 17.0 2.1 3.4 14.5 1.7 2.9 kapurthala (pb) 15.7 1.9 3.1 16.0 1.9 3.2 15.0 1.8 2.9 jalandhar (pb) 15.2 1.8 3.0 15.2 1.8 3.1 15.2 1.8 2.9 hoshiarpur (pb) 15.7 1.8 3.1 15.9 1.9 3.1 15.0 1.7 2.9 shahid bhagat singh nagar (pb) 15.1 1.8 3.0 15.0 1.8 3.0 15.6 1.8 3.0 fatehgarh sahib (pb) 15.4 1.9 3.0 15.1 1.8 2.9 16.0 1.9 3.1 ludhiana (pb) 16.1 1.9 3.1 15.4 1.9 3.1 16.5 2.0 3.1 moga (pb) 15.9 2.0 3.2 15.9 2.0 3.3 15.9 1.9 3.1 firozpur (pb) 17.8 2.2 3.5 18.3 2.3 3.6 16.5 2.0 3.2 muktsar (pb) 16.7 2.1 3.2 16.7 2.1 3.2 16.9 2.0 3.2 faridkot (pb) 16.4 2.0 3.2 16.4 2.0 3.2 16.3 2.0 3.1 bathinda (pb) 15.8 1.9 3.0 15.5 1.9 3.0 16.3 1.9 3.0 mansa (pb) 16.2 2.1 3.2 16.2 2.1 3.3 16.1 1.9 3.1 patiala (pb) 16.3 2.0 3.1 17.2 2.1 3.3 14.9 1.7 2.8 amritsar (pb) 16.5 2.0 3.2 18.0 2.2 3.6 15.2 1.8 2.9 tarn taran (pb) 18.0 2.3 3.6 18.1 2.3 3.7 16.9 2.1 3.4 rupnagar (pb) 15.6 1.9 3.0 15.9 1.9 3.1 14.7 1.7 2.8 sahibzada ajit singh nagar (pb) 16.8 2.0 3.1 17.1 2.1 3.2 16.5 1.9 3.0 sangrur (pb) 16.0 2.0 3.1 15.7 2.0 3.1 16.6 2.0 3.2 barnala (pb) 16.1 2.0 3.1 15.7 2.0 3.1 16.9 2.1 3.2 chandigarh (ch) 16.4 2.0 3.2 20.5 2.9 4.1 16.3 2.0 3.2 chandigarh (ch) 16.4 2.0 3.2 20.5 2.9 4.1 16.3 2.0 3.2 uttarakhand (ut) 19.7 2.4 4.0 20.6 2.6 4.2 17.6 2.1 3.6 uttarkashi (ut) 20.7 2.7 4.2 21.1 2.7 4.3 16.7 2.0 3.3 chamoli (ut) 19.4 2.4 3.9 19.8 2.4 3.9 17.5 2.3 3.7 rudraprayag (ut) 19.6 2.3 3.7 19.8 2.3 3.7 16.1 2.2 3.5 tehri garhwal (ut) 20.2 2.5 4.0 20.6 2.5 4.0 17.3 2.1 3.4 dehradun (ut) 17.4 2.1 3.5 19.3 2.4 4.0 15.8 1.9 3.1 garhwal (ut) 18.1 2.2 3.5 18.4 2.2 3.6 17.0 2.0 3.3 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 99 issn: 2220-184x pithoragarh (ut) 19.1 2.3 3.6 19.3 2.4 3.6 18.3 2.1 3.4 bageshwar (ut) 19.8 2.4 3.7 20.0 2.4 3.8 16.7 1.9 3.3 almora (ut) 18.9 2.3 3.7 19.5 2.3 3.8 13.8 1.6 2.9 champawat (ut) 21.1 2.7 4.3 21.6 2.8 4.4 18.5 2.2 3.8 nainital (ut) 18.9 2.3 3.9 19.8 2.5 4.1 17.6 2.1 3.6 appendix table 1: indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr udham singh nagar (ut) 20.5 2.6 4.3 20.8 2.7 4.4 19.9 2.4 4.2 hardwar (ut) 21.8 2.9 4.8 23.8 3.3 5.4 18.4 2.3 3.8 haryana (hr) 19.2 2.4 3.7 19.9 2.6 3.9 17.9 2.2 3.4 panchkula (hr) 17.2 2.1 3.3 18.7 2.4 3.7 16.0 1.9 3.0 ambala (hr) 16.3 2.0 3.1 17.1 2.1 3.3 15.4 1.8 2.9 yamunanagar (hr) 17.5 2.2 3.4 18.3 2.3 3.6 16.2 1.9 3.1 kurukshetra (hr) 17.4 2.1 3.4 18.1 2.2 3.5 15.5 1.8 3.0 kaithal (hr) 18.6 2.4 3.7 18.9 2.5 3.8 17.7 2.2 3.4 karnal (hr) 18.7 2.3 3.6 19.4 2.5 3.8 17.0 2.0 3.2 panipat (hr) 20.2 2.6 3.9 20.8 2.7 4.2 19.4 2.4 3.7 sonipat (hr) 18.7 2.4 3.7 19.0 2.5 3.8 18.0 2.2 3.4 jind (hr) 18.4 2.4 3.6 18.7 2.5 3.7 17.6 2.1 3.3 fatehabad (hr) 18.6 2.4 3.7 18.9 2.4 3.7 17.5 2.1 3.4 sirsa (hr) 17.7 2.2 3.4 17.9 2.3 3.5 16.9 2.0 3.2 hisar (hr) 18.0 2.3 3.5 18.5 2.4 3.6 16.9 2.1 3.2 bhiwani (hr) 18.8 2.4 3.6 19.0 2.5 3.7 17.8 2.2 3.4 rohtak (hr) 17.7 2.2 3.5 18.3 2.4 3.7 16.7 2.0 3.2 jhajjar (hr) 17.9 2.3 3.4 17.9 2.3 3.5 17.9 2.2 3.3 mahendragarh (hr) 17.6 2.2 3.3 17.6 2.2 3.3 17.4 2.1 3.2 rewari (hr) 18.1 2.2 3.3 18.0 2.3 3.3 18.3 2.2 3.4 gurgaon (hr) 18.9 2.3 3.5 20.2 2.6 3.8 18.3 2.2 3.3 mewat (hr) 32.0 5.2 7.5 32.7 5.4 7.7 26.7 3.8 5.7 faridabad (hr) 20.0 2.5 3.8 23.3 3.1 4.7 19.2 2.3 3.5 palwal (hr) 24.3 3.4 5.0 25.3 3.7 5.3 20.6 2.6 4.1 nct of delhi (dl) 17.4 2.1 3.4 19.5 2.4 3.8 17.3 2.1 3.4 north west (dl) 17.9 2.2 3.5 19.7 2.5 3.9 17.8 2.2 3.5 north (dl) 16.9 2.0 3.4 20.2 2.5 3.8 16.9 2.0 3.4 north east (dl) 19.5 2.4 3.9 22.8 3.0 4.5 19.5 2.4 3.9 east (dl) 16.5 1.9 3.1 14.9 1.7 2.7 16.5 1.9 3.2 new delhi (dl) 13.3 1.5 2.6 na na na 13.3 1.5 2.6 central (dl) 15.5 1.8 3.3 na na na 15.5 1.8 3.3 west (dl) 16.4 2.0 3.2 20.2 2.5 3.7 16.4 2.0 3.2 south west (dl) 16.8 2.0 3.1 18.6 2.3 3.4 16.7 2.0 3.1 south (dl) 17.6 2.1 3.4 20.8 2.8 4.4 17.6 2.1 3.4 rajasthan (rj) 22.4 3.0 4.3 23.5 3.2 4.6 19.0 2.3 3.6 ganganagar (rj) 19.0 2.4 3.7 19.7 2.5 3.8 17.3 2.1 3.3 hanumangarh (rj) 19.3 2.5 3.6 19.6 2.5 3.6 18.2 2.2 3.4 bikaner (rj) 24.4 3.4 4.8 26.9 4.0 5.5 19.6 2.5 3.7 churu (rj) 22.6 3.0 4.3 23.1 3.2 4.4 21.2 2.7 4.0 jhunjhunun (rj) 19.7 2.5 3.7 19.6 2.5 3.7 19.7 2.5 3.8 alwar (rj) 22.9 3.1 4.4 23.8 3.3 4.6 18.9 2.3 3.6 bharatpur (rj) 24.3 3.5 5.1 25.4 3.7 5.3 19.9 2.5 4.0 dhaulpur (rj) 25.8 3.9 5.7 26.7 4.1 5.9 22.4 3.0 4.8 karauli (rj) 23.8 3.5 4.9 24.1 3.6 5.0 22.2 3.0 4.5 sawai madhopur (rj) 22.0 3.0 4.2 22.6 3.1 4.3 19.8 2.5 3.8 dausa (rj) 22.9 3.2 4.6 23.4 3.3 4.7 19.5 2.5 3.8 jaipur (rj) 20.4 2.6 3.8 22.3 3.0 4.2 18.7 2.2 3.5 sikar (rj) 20.6 2.6 3.9 20.8 2.7 3.9 20.3 2.5 3.9 nagaur (rj) 22.3 2.9 4.2 22.5 3.0 4.2 21.6 2.7 4.1 jodhpur (rj) 23.7 3.3 4.7 26.2 3.8 5.3 19.0 2.3 3.5 jaisalmer (rj) 27.6 4.3 5.9 28.6 4.5 6.2 21.2 2.9 4.1 barmer (rj) 27.3 4.2 5.9 27.8 4.3 6.1 20.9 2.7 4.0 jalor (rj) 24.9 3.5 5.1 25.2 3.6 5.2 21.6 2.9 4.3 sirohi (rj) 23.9 3.2 4.8 25.2 3.5 5.2 18.4 2.3 3.6 pali (rj) 21.2 2.8 4.2 21.7 2.9 4.4 19.5 2.4 3.7 ajmer (rj) 21.1 2.7 3.9 23.4 3.1 4.3 17.8 2.1 3.3 tonk (rj) 20.9 2.7 3.8 21.2 2.8 3.8 19.7 2.3 3.9 bundi (rj) 20.8 2.7 3.8 21.4 2.8 3.9 18.5 2.2 3.5 bhilwara (rj) 21.6 2.8 3.8 22.3 2.9 4.0 19.2 2.3 3.3 rajsamand (rj) 22.0 2.9 4.0 22.6 3.0 4.2 18.4 2.2 3.3 dungarpur (rj) 24.8 3.3 5.0 25.3 3.4 5.1 18.2 2.1 3.3 banswara (rj) 25.7 3.5 5.1 26.3 3.6 5.3 18.0 2.1 3.0 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 100 issn: 2220-184x chittaurgarh (rj) 19.9 2.5 3.4 20.3 2.6 3.5 18.1 2.1 3.2 kota (rj) 18.8 2.3 3.5 20.2 2.6 3.9 17.8 2.1 3.3 baran (rj) 21.5 2.8 4.1 22.0 3.0 4.3 19.4 2.4 3.7 jhalawar (rj) 21.4 2.8 3.9 21.7 2.9 3.9 19.4 2.4 3.6 udaipur (rj) 23.6 3.1 4.5 25.4 3.5 4.9 16.1 1.9 2.9 pratapgarh (rj) 24.7 3.3 4.7 25.3 3.4 4.9 17.7 2.1 3.2 uttar pradesh (up) 22.7 3.1 4.9 23.8 3.4 5.2 19.1 2.4 4.1 saharanpur (up) 21.8 2.9 4.9 22.7 3.1 5.2 19.8 2.5 4.4 muzaffarnagar (up) 22.7 3.1 5.1 23.3 3.3 5.3 21.4 2.8 4.7 bijnor (up) 22.5 3.0 5.2 22.8 3.1 5.3 21.5 2.8 5.2 appendix table 1: indirect estimates of cbr,tfr & tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr moradabad (up) 24.1 3.4 5.8 25.7 3.8 6.2 20.8 2.7 4.8 rampur (up) 24.0 3.4 5.8 25.2 3.7 6.1 20.4 2.6 4.9 jyotiba phule nagar (up) 23.9 3.3 5.4 24.5 3.5 5.5 22.0 2.8 5.0 meerut (up) 21.0 2.8 4.5 22.6 3.1 5.1 19.5 2.4 4.1 baghpat (up) 21.7 3.0 4.8 21.7 3.1 4.9 21.5 2.8 4.6 ghaziabad (up) 20.9 2.7 4.4 23.3 3.3 5.3 19.8 2.5 3.9 gautam buddha nagar (up) 21.4 2.9 4.3 23.0 3.3 4.9 20.3 2.6 3.9 bulandshahr (up) 22.6 3.1 5.0 23.0 3.2 5.1 21.2 2.7 4.6 aligarh (up) 22.8 3.2 5.0 23.8 3.5 5.3 20.7 2.7 4.5 mahamaya nagar (up) 23.0 3.3 5.1 23.5 3.4 5.2 21.0 2.8 4.5 mathura (up) 23.0 3.4 5.1 24.2 3.7 5.5 20.0 2.7 4.2 agra (up) 22.3 3.0 4.8 24.8 3.6 5.4 19.3 2.4 4.0 firozabad (up) 22.6 3.2 5.0 23.5 3.4 5.3 21.0 2.8 4.6 mainpuri (up) 22.5 3.2 5.1 22.9 3.3 5.2 20.1 2.5 4.3 budaun (up) 26.1 4.0 6.2 26.9 4.3 6.4 22.7 3.1 5.3 bareilly (up) 23.2 3.3 5.4 25.2 3.8 6.0 19.6 2.6 4.5 pilibhit (up) 22.4 3.1 5.1 23.2 3.3 5.2 19.0 2.4 4.3 shahjahanpur (up) 24.6 3.6 5.6 25.8 4.0 5.9 19.5 2.5 4.4 kheri (up) 24.3 3.5 5.4 24.9 3.7 5.5 19.7 2.5 4.2 sitapur (up) 24.4 3.6 5.5 24.9 3.8 5.6 20.3 2.6 4.6 hardoi (up) 23.5 3.5 5.4 24.1 3.7 5.5 20.0 2.6 4.4 unnao (up) 20.9 2.9 4.7 21.4 3.1 4.9 18.3 2.3 3.9 lucknow (up) 17.7 2.2 3.7 21.5 3.0 4.9 15.7 1.8 3.2 rae bareli (up) 21.2 2.8 4.6 21.7 2.9 4.7 17.0 2.0 3.5 farrukhabad (up) 23.3 3.3 5.3 24.5 3.6 5.6 19.3 2.4 4.2 kannauj (up) 22.9 3.3 5.4 23.2 3.4 5.5 21.3 2.8 4.9 etawah (up) 21.0 2.9 4.5 21.9 3.1 4.8 18.0 2.2 3.7 auraiya (up) 21.4 3.0 4.7 21.9 3.1 4.9 19.2 2.4 4.0 kanpur dehat (up) 20.5 2.9 4.6 20.7 2.9 4.7 19.2 2.5 4.1 kanpur nagar (up) 16.7 2.1 3.5 20.2 2.8 4.6 14.9 1.8 3.1 jalaun (up) 20.0 2.7 4.1 20.6 2.9 4.2 18.2 2.3 3.7 jhansi (up) 18.9 2.4 3.6 20.3 2.7 3.8 17.0 2.1 3.3 lalitpur (up) 24.9 3.6 4.9 25.8 3.8 5.1 19.2 2.4 3.7 hamirpur (up) 20.8 3.0 4.5 21.3 3.1 4.6 18.8 2.4 3.9 mahoba (up) 21.8 3.2 4.7 22.3 3.3 4.8 19.8 2.7 4.2 banda (up) 24.0 3.6 5.3 24.8 3.9 5.6 19.4 2.5 4.1 chitrakoot (up) 25.7 3.9 5.7 26.2 4.1 5.9 20.5 2.7 4.4 fatehpur (up) 22.1 3.1 4.9 22.5 3.2 5.1 18.8 2.3 4.0 pratapgarh (up) 21.6 2.8 4.4 21.8 2.8 4.5 18.6 2.3 3.9 kaushambi (up) 25.1 3.8 5.9 25.4 3.8 6.0 22.0 3.0 5.0 allahabad (up) 22.1 3.0 4.8 24.0 3.4 5.2 16.4 2.0 3.5 bara banki (up) 23.5 3.4 5.4 23.8 3.5 5.5 20.3 2.7 4.7 faizabad (up) 21.8 2.9 4.6 22.6 3.0 4.8 16.9 2.1 3.8 ambedkar nagar (up) 21.5 2.8 4.7 21.7 2.9 4.7 20.1 2.6 4.7 sultanpur (up) 22.3 3.0 4.6 22.5 3.0 4.6 18.3 2.2 3.8 bahraich (up) 27.1 4.1 5.9 27.7 4.2 6.0 21.0 2.7 4.7 shrawasti (up) 27.3 4.1 5.5 27.4 4.1 5.6 22.5 3.0 4.9 balrampur (up) 27.1 4.0 5.9 27.5 4.1 6.0 21.5 2.8 4.9 gonda (up) 24.8 3.5 5.2 25.2 3.6 5.3 19.1 2.4 4.1 siddharthnagar (up) 27.5 4.0 5.9 27.8 4.0 6.0 23.4 3.1 5.2 basti (up) 23.7 3.2 5.1 24.1 3.3 5.1 17.8 2.2 3.7 sant kabir nagar (up) 24.6 3.4 5.4 24.8 3.5 5.4 21.9 2.9 4.8 mahrajganj (up) 23.8 3.3 4.8 24.0 3.4 4.9 19.7 2.5 4.1 gorakhpur (up) 21.3 2.8 4.4 22.4 3.0 4.6 16.5 2.0 3.4 kushinagar (up) 23.9 3.3 5.1 24.1 3.4 5.1 20.2 2.7 4.4 deoria (up) 22.6 2.9 4.6 23.0 3.0 4.7 19.6 2.5 4.1 azamgarh (up) 23.1 3.0 4.8 23.2 3.0 4.8 21.6 2.8 5.0 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 101 issn: 2220-184x mau (up) 23.4 3.2 5.2 23.4 3.2 5.0 23.3 3.1 5.7 ballia (up) 22.1 3.0 4.7 22.3 3.1 4.7 19.8 2.6 4.2 jaunpur (up) 22.7 3.0 4.6 22.9 3.0 4.6 20.3 2.5 4.4 ghazipur (up) 23.1 3.2 4.9 23.3 3.3 5.0 20.7 2.7 4.6 chandauli (up) 23.4 3.3 4.8 23.8 3.4 4.8 20.5 2.6 4.4 varanasi (up) 20.3 2.7 4.2 22.1 3.0 4.5 17.9 2.2 3.8 sant rvidas nagar (bhadohi) (up) 24.0 3.2 4.8 24.3 3.3 4.8 22.4 3.0 4.9 mirzapur (up) 23.8 3.4 5.0 24.5 3.5 5.1 19.8 2.6 4.2 sonbhadra (up) 25.2 3.6 5.1 26.6 3.9 5.5 18.3 2.2 3.5 etah (up) 23.6 3.4 5.3 24.1 3.5 5.4 20.5 2.6 4.4 kanshiram nagar (up) 24.9 3.7 5.7 25.7 3.9 5.9 21.9 2.9 5.0 bihar (br) 26.7 4.0 5.6 27.3 4.1 5.7 21.9 2.9 4.6 pashchim champaran (br) 28.6 4.4 6.1 29.1 4.5 6.2 23.9 3.3 5.1 purba champaran (br) 28.9 4.5 6.1 29.2 4.6 6.2 25.0 3.6 5.3 appendix table 1: indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr sheohar (br) 28.1 4.5 6.1 28.1 4.5 6.1 27.8 4.3 6.0 sitamarhi (br) 27.9 4.3 6.0 28.2 4.4 6.0 23.4 3.3 4.9 madhubani (br) 26.6 3.9 5.4 26.7 4.0 5.4 23.3 3.2 4.8 supaul (br) 28.7 4.3 5.8 28.9 4.4 5.8 24.4 3.5 5.0 araria (br) 29.6 4.5 6.3 30.0 4.6 6.3 24.3 3.4 5.1 kishanganj (br) 29.3 4.4 6.8 29.9 4.5 7.0 24.1 3.3 5.2 purnia (br) 28.8 4.4 6.3 29.6 4.6 6.5 22.6 3.1 4.8 katihar (br) 28.9 4.4 6.3 29.6 4.5 6.5 21.5 2.8 4.5 madhepura (br) 29.3 4.5 6.0 29.5 4.5 6.0 23.7 3.2 4.8 saharsa (br) 29.3 4.5 6.0 29.7 4.6 6.1 23.8 3.3 4.8 darbhanga (br) 26.7 4.0 5.6 27.2 4.1 5.7 21.8 2.9 4.5 muzaffarpur (br) 25.5 3.8 5.4 26.1 3.9 5.5 19.7 2.5 4.0 gopalganj (br) 25.9 3.6 5.3 26.1 3.6 5.4 23.7 3.2 5.0 siwan (br) 24.6 3.4 5.3 24.8 3.5 5.3 20.8 2.7 4.6 saran (br) 25.3 3.7 5.5 25.6 3.7 5.5 22.4 3.1 4.8 vaishali (br) 24.8 3.8 5.2 25.0 3.8 5.3 22.2 3.1 4.7 samastipur (br) 27.1 4.1 5.6 27.3 4.2 5.7 21.0 2.8 4.3 begusarai (br) 26.8 4.1 5.6 27.4 4.2 5.7 24.6 3.5 5.1 khagaria (br) 29.2 4.6 6.2 29.5 4.7 6.3 23.6 3.3 5.1 bhagalpur (br) 26.1 3.9 5.7 27.2 4.2 5.9 21.6 2.9 4.7 banka (br) 26.7 4.0 5.4 26.8 4.0 5.4 23.5 3.3 4.9 munger (br) 24.4 3.5 5.1 25.9 3.9 5.5 20.4 2.7 4.3 lakhisarai (br) 27.2 4.1 5.6 27.6 4.2 5.7 24.4 3.4 5.1 sheikhpura (br) 27.6 4.1 5.8 28.2 4.3 5.8 25.2 3.6 5.3 nalanda (br) 26.3 3.9 5.4 26.8 4.0 5.5 23.3 3.2 5.0 patna (br) 23.5 3.3 4.9 26.7 4.0 5.6 19.4 2.5 4.0 bhojpur (br) 24.7 3.6 5.2 25.3 3.7 5.2 21.6 2.9 4.7 buxar (br) 25.2 3.7 5.3 25.6 3.8 5.4 21.5 2.9 4.6 kaimur (bhabua) (br) 26.8 4.0 5.6 27.0 4.1 5.7 22.2 3.1 4.7 rohtas (br) 25.2 3.6 5.2 25.7 3.8 5.3 21.9 3.0 4.8 aurangabad (br) 26.1 3.8 5.4 26.4 3.9 5.5 23.1 3.1 5.0 gaya (br) 26.0 3.8 5.4 26.8 4.0 5.5 20.3 2.7 4.4 nawada (br) 26.3 3.8 5.3 26.7 3.9 5.3 23.0 3.1 4.9 jamui (br) 26.6 3.9 5.2 26.9 3.9 5.3 23.4 3.2 4.8 jehanabad (br) 25.9 3.8 5.3 26.3 3.9 5.3 22.7 3.1 4.7 arwal (br) 26.3 3.9 5.4 26.4 3.9 5.4 25.4 3.7 5.4 sikkim (sk) 16.2 1.9 3.4 16.7 2.1 3.6 14.6 1.6 2.8 north district (sk) 16.6 2.2 3.9 16.2 2.2 3.8 19.9 2.4 4.4 west district (sk) 18.0 2.2 3.8 18.1 2.2 3.8 15.9 1.8 3.3 south district (sk) 16.8 2.0 3.5 17.2 2.1 3.6 14.8 1.6 2.8 east district (sk) 15.0 1.7 3.1 15.5 1.9 3.3 14.4 1.6 2.8 arunachal pradesh (ar) 22.7 2.9 5.0 23.8 3.1 5.3 18.9 2.2 3.9 tawang (ar) 17.3 2.5 4.9 19.7 2.7 5.3 9.0 1.9 3.3 west kameng (ar) 20.2 2.7 4.4 20.9 2.9 4.6 17.5 2.0 3.5 east kameng (ar) 27.9 3.7 6.0 28.1 3.7 6.0 27.1 3.6 6.1 papum pare (ar) 21.1 2.4 4.3 23.4 2.9 5.0 19.3 2.1 3.8 upper subansiri (ar) 22.8 2.7 4.9 23.2 2.8 5.0 20.6 2.5 4.5 west siang (ar) 20.1 2.5 4.4 20.9 2.7 4.7 17.5 2.1 3.6 east siang (ar) 19.4 2.3 4.2 20.0 2.4 4.5 17.9 2.0 3.5 upper siang (ar) 20.9 2.9 4.9 20.9 3.0 5.1 20.9 2.5 4.3 changlang (ar) 24.9 3.3 5.4 26.0 3.5 5.7 17.4 2.1 3.5 tirap (ar) 26.2 3.6 6.1 27.7 4.0 6.6 19.5 2.4 4.2 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 102 issn: 2220-184x lower subansiri (ar) 19.2 2.2 4.4 19.5 2.2 4.5 17.2 1.8 3.7 kurung kumey (ar) 27.7 3.5 6.0 27.7 3.5 6.0 28.3 3.9 6.7 dibang valley (ar) 20.0 2.6 4.9 20.6 2.8 5.1 18.8 2.4 4.6 lower dibang valley (ar) 22.0 2.7 4.7 23.5 3.0 5.0 16.3 1.9 3.5 lohit (ar) 23.8 3.1 5.0 25.1 3.4 5.4 19.5 2.3 4.0 anjaw (ar) 24.0 3.6 5.9 24.6 3.6 5.9 11.3 2.1 4.5 nagaland (nl) 21.8 2.7 5.6 22.8 2.9 5.9 19.2 2.2 4.7 mon (nl) 23.8 3.2 6.4 24.0 3.2 6.5 22.4 2.8 5.7 mokokchung (nl) 16.3 1.9 4.2 16.5 2.0 4.3 15.5 1.9 3.9 zunheboto (nl) 21.5 2.7 5.7 21.9 2.7 5.7 20.1 2.5 5.8 wokha (nl) 18.3 2.1 4.7 18.9 2.2 4.8 16.1 1.8 4.2 dimapur (nl) 19.8 2.3 4.5 21.4 2.6 5.1 18.4 2.1 4.0 phek (nl) 24.8 3.2 6.5 25.5 3.3 6.6 20.9 2.7 5.5 tuensang (nl) 26.6 3.6 7.2 27.5 3.8 7.4 23.0 2.9 6.2 longleng (nl) 25.6 3.4 6.3 25.9 3.5 6.3 23.8 3.1 5.9 kiphire (nl) 28.6 3.9 7.0 29.1 4.0 6.9 26.5 3.5 7.1 kohima (nl) 20.1 2.4 5.5 21.4 2.7 6.1 18.5 2.1 4.8 peren (nl) 23.8 3.1 6.1 23.7 3.1 6.1 24.2 3.0 6.1 manipur (mn) 19.2 2.3 4.3 19.9 2.4 4.6 17.5 2.0 3.7 senapati (mn) 20.0 2.4 5.3 20.0 2.4 5.3 19.7 2.2 4.5 appendix table 1: indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr tamenglong (mn) 20.2 2.4 5.1 20.1 2.4 5.1 20.8 2.5 5.0 churachandpur (mn) 19.7 2.3 4.6 19.9 2.4 4.7 16.8 1.9 3.8 bishnupur (mn) 19.1 2.3 4.0 19.5 2.3 4.1 18.5 2.2 3.9 thoubal (mn) 20.9 2.5 4.4 21.6 2.6 4.5 19.7 2.3 4.1 imphal west (mn) 17.1 1.9 3.5 18.7 2.2 3.8 16.1 1.8 3.4 imphal east (mn) 18.9 2.2 4.0 20.3 2.4 4.3 16.8 1.8 3.5 ukhrul (mn) 19.7 2.4 5.3 19.8 2.5 5.3 19.0 2.3 5.1 chandel (mn) 17.7 2.0 4.0 17.1 1.9 3.9 21.6 2.7 5.1 mizoram (mz) 21.8 2.6 5.1 25.1 3.3 5.8 18.7 2.1 4.5 mamit (mz) 25.0 3.3 5.8 25.7 3.4 5.9 21.8 2.7 5.2 kolasib (mz) 22.6 2.8 5.4 25.1 3.3 5.9 20.7 2.5 5.0 aizawl (mz) 18.6 2.1 4.4 21.9 2.8 5.3 17.7 1.9 4.2 champhai (mz) 23.3 2.9 5.6 24.4 3.2 5.8 21.6 2.6 5.2 serchhip (mz) 20.6 2.5 5.2 22.4 2.8 5.7 18.8 2.2 4.7 lunglei (mz) 22.3 2.8 5.2 25.7 3.4 5.9 17.8 2.1 4.3 lawngtlai (mz) 26.8 3.5 5.9 28.0 3.8 6.0 20.9 2.5 5.1 saiha (mz) 23.9 3.0 5.7 26.0 3.5 6.0 21.3 2.5 5.3 tripura (tr) 18.0 2.1 3.3 19.3 2.3 3.6 14.1 1.5 2.4 west tripura (tr) 16.0 1.8 2.8 17.4 2.0 3.2 13.8 1.5 2.4 south tripura (tr) 18.5 2.2 3.3 19.3 2.3 3.5 14.0 1.5 2.3 dhalai (tr) 21.4 2.7 4.2 22.0 2.8 4.3 16.2 1.8 2.9 north tripura (tr) 20.3 2.4 4.1 21.3 2.6 4.3 15.3 1.7 2.9 meghalaya (ml) 26.8 3.5 6.5 28.8 4.0 7.0 18.8 2.1 4.6 west garo hills (ml) 24.9 3.2 5.5 25.9 3.4 5.7 17.3 1.9 3.9 east garo hills (ml) 25.9 3.3 5.8 26.8 3.5 5.9 20.5 2.4 4.9 south garo hills (ml) 27.1 3.7 6.4 27.4 3.8 6.4 23.6 3.0 5.7 west khasi hills (ml) 31.3 4.6 8.3 31.6 4.7 8.3 29.1 3.9 8.1 ribhoi (ml) 28.6 4.0 7.1 29.2 4.0 7.2 23.3 3.2 6.3 east khasi hills (ml) 23.6 2.9 6.0 28.8 3.9 7.7 17.2 1.9 4.1 jaintia hills (ml) 31.6 4.5 8.3 32.5 4.7 8.5 19.7 2.2 5.0 assam (as) 21.7 2.7 4.3 22.7 2.9 4.6 15.1 1.7 2.8 kokrajhar (as) 22.4 2.8 4.4 22.9 2.9 4.5 14.7 1.6 2.7 dhubri (as) 26.9 3.7 5.3 28.1 3.9 5.6 16.5 1.9 3.2 goalpara (as) 24.4 3.1 4.8 25.0 3.3 5.0 20.4 2.4 3.9 barpeta (as) 24.7 3.3 4.8 25.6 3.5 5.0 14.6 1.6 2.8 morigaon (as) 24.9 3.3 5.0 25.5 3.4 5.2 17.4 2.0 3.2 nagaon (as) 23.7 3.1 4.8 24.9 3.3 5.1 15.7 1.8 3.0 sonitpur (as) 21.2 2.6 4.2 21.8 2.7 4.4 14.4 1.6 2.7 lakhimpur (as) 21.9 2.7 4.3 22.4 2.8 4.5 17.0 1.9 3.1 dhemaji (as) 22.3 2.8 4.4 22.6 2.9 4.5 18.0 2.1 3.4 tinsukia (as) 20.2 2.4 4.0 21.5 2.6 4.4 14.9 1.7 2.8 dibrugarh (as) 18.2 2.1 3.5 19.1 2.2 3.8 13.9 1.5 2.6 sivasagar (as) 18.0 2.1 3.4 18.3 2.1 3.5 14.9 1.7 2.7 jorhat (as) 16.9 1.9 3.2 17.5 2.0 3.4 14.2 1.6 2.6 golaghat (as) 18.7 2.2 3.6 19.1 2.3 3.7 14.6 1.6 2.7 karbi anglong (as) 23.1 2.9 4.9 23.8 3.0 5.1 17.4 1.9 3.5 dima hasao (as) 21.8 2.7 4.9 23.7 3.0 5.5 17.3 2.0 3.6 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 103 issn: 2220-184x cachar (as) 21.3 2.6 4.5 22.5 2.8 4.9 15.9 1.8 3.1 karimganj (as) 24.6 3.2 5.5 25.5 3.4 5.8 15.6 1.7 3.2 hailakandi (as) 24.4 3.2 5.5 25.1 3.3 5.7 14.5 1.6 2.9 bongaigaon (as) 22.8 2.9 4.4 24.2 3.1 4.7 14.9 1.6 2.7 chirang (as) 22.4 2.8 4.4 22.8 2.8 4.5 17.1 2.0 3.2 kamrup (as) 19.5 2.4 3.8 20.0 2.5 3.9 14.0 1.5 2.7 kamrup metropolitan (as) 14.7 1.6 2.7 18.6 2.2 3.6 13.9 1.5 2.5 nalbari (as) 18.2 2.2 3.6 18.7 2.3 3.7 13.8 1.5 2.6 baksa (as) 19.3 2.3 3.7 19.3 2.3 3.7 18.2 2.2 3.4 darrang (as) 24.6 3.2 4.9 25.2 3.4 5.0 15.1 1.7 2.8 udalguri (as) 20.2 2.4 4.0 20.5 2.5 4.1 14.6 1.6 2.7 west bengal (wb) 17.1 2.0 3.0 18.5 2.2 3.3 14.1 1.6 2.5 darjiling (wb) 15.9 1.8 3.0 17.0 1.9 3.3 14.1 1.5 2.6 jalpaiguri (wb) 17.6 2.0 3.3 18.3 2.1 3.5 15.5 1.8 2.8 koch bihar (wb) 17.9 2.2 3.2 18.5 2.2 3.3 13.0 1.4 2.3 uttar dinajpur (wb) 23.9 3.2 4.9 24.7 3.4 5.2 18.1 2.2 3.5 dakshin dinajpur (wb) 17.0 2.0 3.0 17.8 2.1 3.1 12.4 1.4 2.1 maldah (wb) 22.3 2.9 4.3 22.7 3.0 4.4 20.0 2.5 3.8 murshidabad (wb) 20.9 2.6 3.8 20.9 2.6 3.8 20.9 2.6 4.1 birbhum (wb) 18.6 2.2 3.2 19.1 2.3 3.3 15.5 1.7 2.7 barddhaman (wb) 15.8 1.8 2.7 16.2 1.9 2.7 15.3 1.7 2.7 nadia (wb) 15.2 1.8 2.6 16.2 1.9 2.8 12.4 1.4 2.1 north 24 parganas (wb) 14.3 1.6 2.5 17.0 2.0 2.9 12.3 1.4 2.1 hugli (wb) 14.2 1.6 2.4 15.1 1.7 2.5 12.9 1.5 2.3 bankura (wb) 17.0 2.1 3.0 17.3 2.1 3.0 13.3 1.5 2.3 appendix table 1: indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr puruliya (wb) 20.2 2.6 3.8 20.6 2.7 3.9 17.6 2.1 3.3 haora (wb) 15.7 1.8 2.8 16.8 2.0 2.9 15.1 1.7 2.7 kolkata (wb) 11.4 1.3 2.2 na na na 11.4 1.3 2.2 south 24 parganas (wb) 18.5 2.2 3.2 19.5 2.4 3.4 15.4 1.7 2.6 paschim medinipur (wb) 17.0 2.0 2.9 17.4 2.1 3.0 13.9 1.5 2.5 purba medinipur (wb) 17.0 2.0 2.9 17.1 2.0 2.9 15.8 1.8 2.8 jharkhand (jh) 23.6 3.2 4.8 25.1 3.5 5.1 18.9 2.3 3.8 garhwa (jh) 26.3 4.0 5.5 26.6 4.0 5.6 21.8 3.0 4.5 chatra (jh) 27.2 3.9 5.5 27.5 4.0 5.6 21.9 3.0 4.8 kodarma (jh) 26.3 3.7 5.2 27.2 3.9 5.3 22.8 3.1 4.5 giridih (jh) 26.9 3.9 5.2 27.3 4.0 5.3 22.0 2.8 4.5 deoghar (jh) 25.5 3.6 4.9 26.7 3.9 5.2 19.7 2.5 3.9 godda (jh) 26.2 3.8 5.3 26.5 3.8 5.3 21.3 2.8 4.2 sahibganj (jh) 27.5 3.9 5.7 28.3 4.1 5.8 22.6 3.1 4.8 pakur (jh) 27.9 3.8 5.6 28.2 3.9 5.7 24.0 3.2 5.1 dhanbad (jh) 20.4 2.7 4.2 22.3 3.0 4.5 19.1 2.4 4.0 bokaro (jh) 20.9 2.7 4.1 22.9 3.1 4.5 18.6 2.3 3.7 lohardaga (jh) 24.8 3.4 5.5 25.5 3.6 5.7 20.1 2.5 4.4 purbi singhbhum (jh) 18.7 2.2 3.6 20.7 2.6 4.1 17.0 2.0 3.3 palamu (jh) 24.9 3.6 5.2 25.5 3.8 5.3 20.5 2.7 4.3 latehar (jh) 27.2 3.9 6.0 27.6 4.0 6.1 21.8 2.9 4.7 hazaribagh (jh) 23.7 3.2 4.7 24.6 3.4 4.9 18.9 2.3 3.9 ramgarh (jh) 20.8 2.7 4.2 22.0 2.9 4.4 19.2 2.4 3.9 dumka (jh) 23.7 3.2 4.6 24.1 3.2 4.6 18.8 2.4 3.7 jamtara (jh) 23.7 3.2 4.6 24.2 3.3 4.7 18.8 2.4 3.7 ranchi (jh) 20.2 2.6 4.2 22.3 3.0 4.8 17.5 2.1 3.6 khunti (jh) 23.3 3.1 5.1 23.8 3.2 5.2 19.0 2.3 4.0 gumla (jh) 24.7 3.4 5.7 25.0 3.5 5.7 19.6 2.4 4.4 simdega (jh) 22.6 3.0 5.2 22.8 3.1 5.3 19.0 2.3 4.4 pashchimi singhbhum (jh) 24.9 3.2 5.6 26.1 3.5 5.9 18.4 2.2 3.9 saraikela-kharsawan (jh) 21.6 2.8 4.5 21.9 2.9 4.7 20.7 2.5 4.0 odisha (orissa) (or) 18.4 2.2 3.6 19.0 2.3 3.7 15.7 1.8 2.9 bargarh (or) 15.6 1.8 3.0 15.6 1.8 3.0 16.0 1.8 3.0 jharsuguda (or) 16.1 1.9 3.2 15.5 1.8 3.2 17.1 2.0 3.3 sambalpur (or) 16.4 1.9 3.3 16.7 2.0 3.4 15.7 1.7 2.9 debagarh (or) 18.4 2.2 3.6 18.5 2.3 3.7 17.0 2.0 3.4 sundargarh (or) 18.5 2.2 3.7 19.8 2.4 4.1 16.2 1.8 3.1 kendujhar (or) 20.8 2.6 4.1 21.1 2.6 4.2 19.2 2.3 3.8 mayurbhanj (or) 20.7 2.6 4.1 21.1 2.7 4.2 15.0 1.7 2.8 baleshwar (or) 18.3 2.2 3.4 18.6 2.3 3.5 16.2 1.8 2.9 bhadrak (or) 17.8 2.1 3.5 17.7 2.1 3.5 18.0 2.1 3.6 kendrapara (or) 16.4 1.9 3.2 16.4 2.0 3.2 16.0 1.9 3.2 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 104 issn: 2220-184x jagatsinghapur (or) 14.3 1.7 2.7 14.2 1.7 2.7 15.3 1.7 2.8 cuttack (or) 15.1 1.8 2.9 15.6 1.9 3.0 13.8 1.5 2.6 jajapur (or) 17.1 2.0 3.4 17.1 2.0 3.4 17.5 2.0 3.3 dhenkanal (or) 17.0 2.0 3.2 17.2 2.1 3.3 14.8 1.7 2.8 anugul (or) 17.5 2.1 3.3 17.8 2.2 3.4 15.5 1.7 2.8 nayagarh (or) 16.4 2.1 3.0 16.5 2.1 3.0 14.9 1.8 2.7 khordha (or) 15.6 1.8 2.9 16.5 2.0 3.1 14.6 1.6 2.6 puri (or) 15.2 1.8 2.9 15.3 1.8 3.0 14.3 1.6 2.7 ganjam (or) 17.8 2.2 3.4 18.6 2.3 3.6 14.9 1.7 2.9 gajapati (or) 22.6 2.8 4.6 23.5 3.0 4.8 15.6 1.8 3.0 kandhamal (or) 22.6 2.9 4.8 23.2 3.0 4.9 16.8 1.9 3.3 baudh (or) 20.3 2.6 4.1 20.5 2.6 4.1 15.5 1.8 3.1 subarnapur (or) 17.5 2.2 3.6 17.6 2.2 3.7 15.9 1.9 3.1 balangir (or) 18.7 2.4 3.8 19.1 2.4 3.9 15.9 1.8 3.0 nuapada (or) 20.9 2.7 4.1 21.0 2.7 4.2 18.2 2.1 3.5 kalahandi (or) 20.5 2.6 4.0 20.9 2.7 4.0 16.8 1.9 3.2 rayagada (or) 23.3 2.9 4.7 24.5 3.1 5.1 16.3 1.8 3.0 nabarangapur (or) 24.8 3.3 4.8 25.3 3.4 4.9 18.4 2.2 3.6 koraput (or) 23.9 3.1 4.7 25.3 3.3 5.0 17.1 1.9 3.2 malkangiri (or) 26.0 3.5 5.3 26.5 3.6 5.4 20.1 2.5 4.1 chhattisgarh (ct) 20.7 2.6 4.1 21.6 2.7 4.3 17.9 2.1 3.5 koriya (ct) 20.8 2.6 4.0 22.8 2.9 4.4 16.6 1.9 3.2 surguja (ct) 23.2 3.1 4.6 23.8 3.2 4.7 18.5 2.2 3.6 jashpur (ct) 20.5 2.6 4.1 20.6 2.6 4.2 18.7 2.2 3.9 raigarh (ct) 18.9 2.3 3.6 19.1 2.4 3.7 18.0 2.1 3.5 korba (ct) 20.4 2.5 4.0 21.7 2.8 4.3 18.1 2.1 3.4 janjgir champa (ct) 20.2 2.6 4.3 20.4 2.7 4.3 18.7 2.2 3.8 bilaspur (ct) 22.1 2.9 4.5 23.5 3.1 4.8 18.2 2.1 3.6 kabeerdham (ct) 24.7 3.3 4.8 25.1 3.3 4.8 21.1 2.6 4.1 rajnandgaon (ct) 19.9 2.4 3.9 20.5 2.5 4.0 17.0 2.0 3.4 appendix table 1: indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr durg (ct) 18.7 2.2 3.6 19.9 2.5 3.8 16.7 1.9 3.1 raipur (ct) 20.5 2.5 4.0 21.4 2.7 4.3 18.9 2.2 3.6 mahasamund (ct) 18.7 2.3 3.6 18.7 2.3 3.6 18.1 2.1 3.6 dhamtari (ct) 18.5 2.2 3.6 18.8 2.3 3.6 17.0 1.9 3.3 uttar bastar kanker (ct) 19.6 2.4 4.0 20.0 2.4 4.0 16.6 1.8 3.3 bastar (ct) 22.3 2.7 4.5 23.2 2.9 4.7 16.8 1.9 3.4 narayanpur (ct) 25.6 3.3 5.8 27.0 3.6 6.1 17.9 2.1 4.0 dakshin bastar dantewada (ct) 23.1 2.8 4.8 23.9 2.9 5.0 19.8 2.4 4.0 bijapur (ct) 26.3 3.3 5.6 26.8 3.4 5.7 21.9 2.7 4.8 madhya pradesh (mp) 21.7 2.9 4.3 23.0 3.1 4.6 18.1 2.2 3.5 sheopur (mp) 24.3 3.4 4.8 25.0 3.5 4.9 21.0 2.7 4.3 morena (mp) 22.3 3.1 4.5 22.9 3.3 4.7 20.3 2.6 4.0 bhind (mp) 21.0 2.9 4.3 21.4 3.1 4.4 19.8 2.6 3.9 gwalior (mp) 18.9 2.4 3.7 22.3 3.1 4.6 16.8 2.0 3.3 datia (mp) 20.5 2.8 4.0 21.0 2.9 4.1 18.9 2.4 3.8 shivpuri (mp) 24.1 3.5 4.9 25.0 3.7 5.1 19.9 2.5 4.0 tikamgarh (mp) 23.0 3.2 4.4 23.6 3.3 4.5 20.2 2.6 4.0 chhatarpur (mp) 23.4 3.4 4.9 24.5 3.7 5.2 19.8 2.6 4.1 panna (mp) 23.5 3.4 5.0 24.2 3.5 5.1 19.0 2.4 4.0 sagar (mp) 21.7 3.0 4.5 23.1 3.3 4.8 18.6 2.3 3.9 damoh (mp) 22.1 3.0 4.4 23.0 3.2 4.5 18.4 2.3 3.8 satna (mp) 21.9 2.9 4.4 22.8 3.1 4.6 18.7 2.3 3.7 rewa (mp) 21.8 2.9 4.4 22.5 3.1 4.6 18.2 2.2 3.6 umaria (mp) 23.2 3.0 4.5 24.2 3.2 4.7 18.1 2.1 3.5 neemuch (mp) 19.3 2.4 3.5 20.0 2.5 3.5 17.6 2.1 3.3 mandsaur (mp) 19.7 2.5 3.5 20.3 2.6 3.6 17.5 2.1 3.2 ratlam (mp) 21.8 2.8 4.1 23.7 3.2 4.5 17.5 2.1 3.3 ujjain (mp) 20.0 2.5 3.7 21.7 2.9 4.0 17.2 2.1 3.2 shajapur (mp) 21.4 2.9 4.0 21.8 3.0 4.1 19.7 2.5 3.7 dewas (mp) 21.4 2.8 4.0 22.4 3.0 4.3 18.8 2.3 3.5 dhar (mp) 23.9 3.1 4.6 24.6 3.3 4.8 20.9 2.6 3.9 indore (mp) 18.5 2.2 3.4 21.2 2.7 3.9 17.6 2.1 3.2 khargone (west nimar) (mp) 23.4 3.1 4.7 24.2 3.3 4.8 18.8 2.3 3.7 barwani (mp) 27.6 3.9 5.6 28.9 4.2 5.9 20.1 2.5 4.0 rajgarh (mp) 22.1 3.0 4.2 22.5 3.1 4.3 20.7 2.6 4.1 vidisha (mp) 23.9 3.4 5.1 24.9 3.8 5.4 20.4 2.6 4.1 bhopal (mp) 18.6 2.3 3.6 23.7 3.3 5.0 17.4 2.1 3.3 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 105 issn: 2220-184x sehore (mp) 22.0 3.0 4.4 22.7 3.2 4.6 19.1 2.4 3.8 raisen (mp) 22.8 3.2 4.7 23.3 3.3 4.9 20.9 2.7 4.2 betul (mp) 19.6 2.4 4.0 20.6 2.6 4.2 15.6 1.7 3.0 harda (mp) 21.4 2.8 4.2 22.3 3.0 4.4 18.1 2.2 3.6 hoshangabad (mp) 19.4 2.5 3.9 20.7 2.8 4.2 16.4 1.9 3.3 katni (mp) 21.9 2.8 4.2 23.0 3.1 4.5 17.5 2.1 3.4 jabalpur (mp) 17.5 2.1 3.4 20.1 2.6 3.8 15.6 1.8 3.0 narsimhapur (mp) 19.0 2.4 3.6 19.5 2.5 3.7 16.5 2.0 3.2 dindori (mp) 22.4 2.8 4.2 22.6 2.8 4.2 18.4 2.1 3.5 mandla (mp) 20.5 2.5 3.9 21.2 2.6 4.0 15.9 1.8 3.2 chhindwara (mp) 19.1 2.3 3.9 20.1 2.5 4.1 15.8 1.8 3.2 seoni (mp) 19.3 2.4 3.8 19.8 2.4 3.9 16.0 1.8 3.2 balaghat (mp) 18.5 2.2 3.6 18.9 2.2 3.7 15.9 1.8 3.1 guna (mp) 24.4 3.4 4.9 25.5 3.7 5.1 21.1 2.7 4.1 ashoknagar (mp) 24.1 3.4 4.8 24.8 3.6 5.0 21.1 2.7 4.2 shahdol (mp) 21.6 2.7 4.0 22.8 2.9 4.2 17.1 2.0 3.3 anuppur (mp) 20.4 2.5 3.8 21.6 2.7 4.0 17.3 2.0 3.3 sidhi (mp) 24.9 3.4 5.0 25.3 3.5 5.1 20.7 2.6 4.1 singrauli (mp) 25.5 3.6 5.2 26.8 3.9 5.5 20.1 2.5 3.9 jhabua (mp) 29.7 4.3 6.1 30.6 4.5 6.3 20.8 2.5 4.0 alirajpur (mp) 29.5 4.2 6.5 30.2 4.4 6.7 21.3 2.6 4.3 khandwa (east nimar) (mp) 23.0 3.1 4.7 24.1 3.3 4.9 18.6 2.3 3.8 burhanpur (mp) 23.2 3.1 4.7 25.2 3.5 5.1 19.2 2.4 3.9 gujarat (gj) 18.7 2.3 3.5 20.2 2.6 3.8 16.7 2.0 3.0 kachchh (gj) 21.7 2.8 4.3 23.2 3.1 4.7 18.9 2.3 3.5 banas kantha (gj) 23.8 3.1 4.6 24.5 3.3 4.8 19.4 2.3 3.6 patan (gj) 20.2 2.6 3.8 21.1 2.7 4.0 16.8 2.0 3.1 mahesana (gj) 17.2 2.1 3.1 17.8 2.2 3.2 15.6 1.8 2.7 sabar kantha (gj) 20.3 2.6 3.8 20.8 2.6 3.9 17.7 2.1 3.2 gandhinagar (gj) 17.4 2.1 3.0 18.3 2.2 3.2 16.3 1.9 2.8 ahmadabad (gj) 16.9 2.0 3.0 20.3 2.6 3.7 16.2 1.9 2.9 surendranagar (gj) 20.0 2.6 3.9 21.3 2.8 4.2 16.6 2.0 3.1 rajkot (gj) 16.8 2.0 3.0 17.6 2.2 3.3 16.2 1.9 2.8 jamnagar (gj) 18.0 2.2 3.5 18.8 2.4 3.7 17.0 2.0 3.1 porbandar (gj) 16.9 2.1 3.2 17.9 2.2 3.4 15.9 1.9 3.0 appendix table 1: indirect estimates of cbr,tfr & tmfr-total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr junagadh (gj) 17.1 2.1 3.4 17.6 2.2 3.5 16.2 1.9 3.1 amreli (gj) 17.0 2.1 3.4 17.3 2.2 3.5 16.2 1.9 3.1 bhavnagar (gj) 19.5 2.4 3.9 20.9 2.7 4.3 17.5 2.1 3.3 anand (gj) 17.6 2.2 3.2 18.3 2.3 3.3 16.1 1.9 2.9 kheda (gj) 18.4 2.3 3.3 18.9 2.4 3.4 16.5 2.0 3.1 panch mahals (gj) 21.7 2.8 4.2 22.2 2.9 4.3 18.6 2.2 3.4 dohad (gj) 27.5 3.8 5.6 28.1 3.9 5.8 20.6 2.5 3.9 vadodara (gj) 17.4 2.1 3.1 19.9 2.5 3.6 15.0 1.7 2.6 narmada (gj) 19.4 2.4 3.7 19.9 2.5 3.8 14.8 1.7 2.8 bharuch (gj) 17.1 2.1 3.2 17.6 2.2 3.4 16.2 1.9 2.9 the dangs (gj) 26.1 3.4 5.1 27.2 3.7 5.2 17.1 2.0 3.8 navsari (gj) 14.9 1.7 2.7 14.8 1.7 2.7 15.0 1.7 2.7 valsad (gj) 18.4 2.3 3.4 19.5 2.4 3.6 16.7 2.0 3.1 surat (gj) 17.3 2.2 3.2 16.6 2.0 3.1 17.5 2.2 3.2 tapi (gj) 16.3 1.9 2.9 16.3 1.9 2.9 16.4 1.9 3.0 daman & diu (dd) 15.5 2.3 3.5 18.1 2.3 3.9 14.6 2.3 3.4 diu (dd) 18.7 2.2 4.1 21.5 2.7 5.0 15.5 1.7 3.1 daman (dd) 14.6 2.3 3.3 15.2 2.0 3.0 14.5 2.4 3.4 dadra & nagar haveli (dn) 21.2 2.9 4.3 22.7 3.1 4.8 19.4 2.7 3.7 dadra & nagar haveli (dn) 21.2 2.9 4.3 22.7 3.1 4.8 19.4 2.7 3.7 maharashtra (mh) 17.1 2.1 3.2 18.0 2.3 3.4 16.0 1.9 3.0 nandurbar (mh) 21.6 2.8 4.3 22.4 2.9 4.4 17.7 2.2 3.6 dhule (mh) 19.5 2.5 3.8 20.4 2.7 4.0 17.2 2.1 3.4 jalgaon (mh) 18.1 2.3 3.5 18.7 2.4 3.6 16.9 2.0 3.2 buldana (mh) 18.3 2.3 3.5 18.4 2.4 3.5 17.6 2.1 3.4 akola (mh) 16.8 2.1 3.3 17.0 2.1 3.3 16.5 1.9 3.2 washim (mh) 18.3 2.4 3.6 18.4 2.4 3.6 18.3 2.3 3.6 amravati (mh) 15.7 1.9 3.1 16.1 2.0 3.2 15.0 1.7 2.9 wardha (mh) 14.4 1.7 2.8 14.6 1.8 2.8 14.0 1.6 2.6 nagpur (mh) 15.3 1.8 2.9 15.9 1.9 3.1 15.1 1.7 2.8 bhandara (mh) 15.3 1.8 3.0 15.6 1.9 3.0 14.3 1.6 2.8 gondiya (mh) 15.7 1.8 3.0 15.9 1.9 3.0 14.8 1.7 2.8 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 106 issn: 2220-184x gadchiroli (mh) 16.7 2.0 3.2 16.9 2.0 3.2 14.8 1.6 2.8 chandrapur (mh) 15.2 1.8 2.8 15.6 1.9 2.9 14.5 1.6 2.6 yavatmal (mh) 17.2 2.1 3.3 17.5 2.2 3.4 15.8 1.8 3.0 nanded (mh) 19.8 2.6 3.9 20.1 2.7 3.9 19.0 2.3 3.7 hingoli (mh) 20.2 2.7 3.9 20.3 2.7 3.9 19.7 2.5 3.9 parbhani (mh) 20.0 2.7 3.9 20.2 2.7 3.9 19.7 2.5 3.9 jalna (mh) 20.7 2.8 4.1 20.9 2.9 4.1 19.9 2.5 3.8 aurangabad (mh) 20.4 2.6 3.8 20.8 2.8 4.0 19.8 2.4 3.6 nashik (mh) 19.4 2.4 3.6 20.2 2.6 3.8 18.2 2.2 3.4 thane (mh) 17.3 2.1 3.2 20.7 2.6 3.9 16.2 1.9 2.9 mumbai suburban (mh) 14.4 1.7 2.8 na na na 14.4 1.7 2.8 mumbai (mh) 12.9 1.6 2.7 na na na 12.9 1.6 2.7 raigarh (mh) 16.5 1.9 3.0 16.5 2.0 3.1 16.5 1.9 2.8 pune (mh) 16.5 1.9 2.9 16.9 2.1 3.1 16.1 1.9 2.9 ahmadnagar (mh) 17.6 2.2 3.2 17.8 2.3 3.3 16.7 2.0 3.0 bid (mh) 19.5 2.6 3.8 19.5 2.7 3.8 19.4 2.4 3.7 latur (mh) 18.8 2.5 3.8 18.8 2.6 3.8 18.7 2.3 3.6 osmanabad (mh) 17.8 2.4 3.6 17.7 2.4 3.6 18.4 2.3 3.6 solapur (mh) 17.9 2.2 3.4 18.4 2.4 3.5 16.8 2.0 3.2 satara (mh) 15.4 1.9 2.8 15.4 1.9 2.9 15.4 1.8 2.8 ratnagiri (mh)) 14.5 1.7 2.8 14.5 1.7 2.8 14.9 1.7 2.7 sindhudurg (mh) 12.7 1.5 2.5 12.6 1.5 2.5 13.3 1.5 2.5 kolhapur (mh) 15.3 1.8 2.7 15.3 1.9 2.8 15.2 1.7 2.7 sangli (mh) 15.8 1.9 2.9 15.9 2.0 2.9 15.5 1.8 2.8 andhra pradesh (old)(ap+ts) 16.1 1.9 2.9 16.3 2.0 3.0 15.6 1.7 2.8 telangana state (ts) 16.5 2.0 3.0 16.6 2.0 3.1 16.4 1.9 3.0 adilabad (ts) 17.0 2.1 3.3 17.8 2.2 3.4 14.9 1.7 2.8 nizamabad (ts) 16.6 2.0 3.1 16.4 2.0 3.0 17.1 2.0 3.3 karimnagar (ts) 13.6 1.6 2.5 13.3 1.6 2.5 14.4 1.6 2.6 medak (ts) 17.8 2.2 3.3 17.9 2.2 3.4 17.5 2.0 3.1 hyderabad (ts) 17.3 2.0 3.3 na na na 17.3 2.0 3.3 rangareddy (ts) 17.2 2.0 3.0 18.0 2.3 3.5 16.8 1.9 2.9 mahbubnagar (ts) 19.3 2.4 3.6 19.7 2.5 3.7 17.3 2.0 3.3 nalgonda (ts) 15.9 1.9 2.9 16.0 2.0 2.9 15.4 1.7 2.8 warangal (ts) 14.8 1.8 2.7 15.0 1.8 2.8 14.3 1.6 2.6 khammam (ts) 15.2 1.7 2.7 15.4 1.8 2.8 14.6 1.6 2.5 andhra pradesh (new) (ap) 15.7 1.8 2.8 16.1 1.9 2.9 14.9 1.6 2.6 srikakulam (ap) 15.7 1.8 2.9 15.8 1.9 2.9 14.7 1.6 2.6 vizianagaram (ap) 15.5 1.8 2.8 15.8 1.9 2.9 14.2 1.6 2.5 appendix table 1: indirect estimates of cbr,tfr & tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr visakhapatnam (ap) 15.6 1.8 2.7 17.1 2.0 3.1 14.0 1.5 2.4 east godavari (ap) 15.1 1.7 2.7 15.4 1.8 2.7 14.4 1.5 2.5 west godavari (ap) 14.6 1.7 2.6 14.8 1.7 2.6 13.7 1.5 2.4 krishna (ap) 14.3 1.6 2.5 14.4 1.7 2.6 14.1 1.5 2.5 guntur (ap) 15.1 1.7 2.6 15.3 1.8 2.7 14.7 1.6 2.6 prakasam (ap) 16.6 2.0 2.9 17.0 2.1 3.0 15.1 1.7 2.6 sri potti sriramulu nellore (ap) 15.3 1.7 2.7 15.8 1.8 2.8 13.9 1.5 2.5 y.s.r. (ap) 17.0 2.0 3.1 17.2 2.1 3.1 16.7 1.9 3.0 kurnool (ap) 18.6 2.2 3.4 19.1 2.4 3.5 17.4 2.0 3.2 anantapur (ap) 16.2 1.9 2.9 16.4 2.0 3.0 15.9 1.8 2.9 chittoor (ap) 15.7 1.9 2.9 16.0 1.9 2.9 14.9 1.7 2.7 karnataka (ka) 16.8 2.0 3.1 17.3 2.1 3.3 16.1 1.8 2.9 belgaum (ka) 18.7 2.3 3.5 19.4 2.5 3.7 16.6 1.9 3.0 bagalkot (ka) 20.6 2.6 4.0 21.4 2.7 4.1 18.9 2.2 3.6 bijapur (ka) 20.9 2.7 4.1 21.4 2.8 4.2 19.3 2.3 3.7 bidar (ka) 19.3 2.5 4.0 19.3 2.6 4.1 19.5 2.4 3.9 raichur (ka) 21.1 2.6 4.1 21.8 2.7 4.2 19.1 2.2 3.7 koppal (ka) 20.8 2.6 4.2 21.1 2.7 4.2 19.2 2.3 3.7 gadag (ka) 17.7 2.1 3.4 18.0 2.2 3.5 17.1 2.0 3.3 dharwad (ka) 17.0 2.0 3.2 17.9 2.2 3.4 16.4 1.9 3.1 uttara kannada (ka) 15.1 1.8 2.9 15.2 1.8 2.9 15.0 1.7 2.9 haveri (ka) 17.5 2.1 3.4 17.4 2.1 3.4 17.7 2.1 3.5 bellary (ka) 20.0 2.4 3.8 20.7 2.6 4.0 18.8 2.2 3.4 chitradurga (ka) 16.0 1.9 2.9 16.0 1.9 2.9 15.6 1.7 2.8 davanagere (ka) 16.2 1.9 3.0 16.2 1.9 3.0 16.3 1.8 2.9 shimoga (ka) 15.3 1.7 2.8 15.5 1.8 2.8 14.8 1.6 2.7 udupi (ka) 12.7 1.4 2.4 12.8 1.4 2.4 12.5 1.4 2.3 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 107 issn: 2220-184x chikmagalur (ka) 13.6 1.5 2.4 13.5 1.5 2.4 14.3 1.5 2.6 tumkur (ka) 14.4 1.7 2.6 14.2 1.7 2.6 15.2 1.7 2.7 bangalore (ka) 15.4 1.7 2.6 16.1 1.9 2.8 15.3 1.7 2.6 mandya (ka) 14.0 1.6 2.5 13.7 1.6 2.4 15.0 1.6 2.6 hassan (ka) 13.7 1.6 2.4 13.4 1.5 2.3 14.8 1.6 2.6 dakshina kannada (ka) 14.5 1.6 2.8 14.8 1.6 2.9 14.2 1.5 2.7 kodagu (ka) 14.7 1.7 2.7 14.7 1.7 2.7 14.6 1.6 2.7 mysore (ka) 14.8 1.7 2.6 15.2 1.8 2.7 14.3 1.5 2.5 chamarajanagar (ka) 14.3 1.6 2.5 14.2 1.6 2.5 15.0 1.6 2.7 gulbarga (ka) 20.6 2.6 4.2 21.2 2.8 4.4 19.3 2.3 3.8 yadgir (ka) 23.2 3.0 4.8 23.7 3.2 4.9 21.1 2.6 4.4 kolar (ka) 16.2 1.9 3.0 16.0 1.9 3.0 16.5 1.9 3.1 chikkaballapura (ka) 15.4 1.8 2.7 15.0 1.8 2.7 16.8 1.9 3.0 bangalore rural (ka) 15.4 1.8 2.8 15.2 1.8 2.8 15.9 1.8 2.8 ramanagara (ka) 14.4 1.7 2.7 13.7 1.6 2.6 16.5 1.9 3.1 goa (ga) 14.2 1.6 2.7 14.0 1.6 2.7 14.3 1.7 2.8 north goa (ga) 13.6 1.6 2.6 13.5 1.6 2.6 13.7 1.6 2.6 south goa (ga) 15.0 1.7 2.9 14.7 1.7 2.9 15.1 1.7 2.9 lakshadweep (ld) 16.2 1.9 3.2 18.5 2.3 3.7 15.6 1.8 3.1 lakshadweep (ld) 16.2 1.9 3.2 18.5 2.3 3.7 15.6 1.8 3.1 kerala (kl) 15.0 1.7 2.6 15.1 1.7 2.7 14.9 1.7 2.6 kasaragod (kl) 16.9 1.9 3.1 16.4 1.8 3.0 17.6 1.9 3.1 kannur (kl) 15.3 1.7 2.6 15.2 1.7 2.7 15.4 1.7 2.6 wayanad (kl) 16.5 1.9 2.9 16.5 1.9 2.9 16.5 1.8 2.8 kozhikode (kl) 15.7 1.7 2.6 16.2 1.8 2.7 15.4 1.7 2.6 malappuram (kl) 19.9 2.2 3.4 19.9 2.2 3.4 19.9 2.2 3.4 palakkad (kl) 15.4 1.8 2.8 15.6 1.8 2.8 15.0 1.7 2.7 thrissur (kl) 14.0 1.6 2.5 14.2 1.6 2.5 14.0 1.6 2.4 ernakulam (kl) 13.4 1.6 2.4 13.0 1.6 2.4 13.6 1.6 2.4 idukki (kl) 14.0 1.6 2.5 14.0 1.6 2.5 14.7 1.7 2.7 kottayam (kl) 13.1 1.6 2.5 13.1 1.6 2.5 13.0 1.5 2.5 alappuzha (kl) 13.2 1.5 2.3 13.3 1.5 2.3 13.1 1.5 2.3 pathanamthitta (kl) 12.0 1.4 2.2 12.0 1.4 2.2 12.1 1.4 2.2 kollam (kl) 14.1 1.6 2.4 13.9 1.5 2.4 14.3 1.6 2.4 thiruvananthapuram (kl) 13.4 1.5 2.3 14.0 1.5 2.4 13.0 1.5 2.3 tamil nadu (tn) 15.0 1.7 2.7 15.4 1.8 2.8 14.5 1.6 2.5 thiruvallur (tn) 15.5 1.7 2.6 15.7 1.8 2.8 15.3 1.7 2.5 chennai (tn) 14.0 1.5 2.4 na na na 14.0 1.5 2.4 kancheepuram (tn) 15.2 1.7 2.7 15.6 1.7 2.8 15.0 1.6 2.5 vellore (tn) 16.0 1.8 2.9 16.2 1.9 3.0 15.6 1.7 2.9 tiruvannamalai (tn) 16.1 1.9 2.9 16.3 1.9 3.0 15.3 1.7 2.8 viluppuram (tn) 17.1 2.0 3.1 17.3 2.0 3.2 15.9 1.8 2.8 salem (tn) 14.7 1.7 2.6 15.1 1.8 2.7 14.3 1.6 2.5 namakkal (tn) 13.0 1.5 2.3 12.8 1.5 2.4 13.1 1.5 2.3 erode (tn) 12.7 1.4 2.2 12.5 1.4 2.2 13.0 1.4 2.2 appendix table 1: indirect estimates of cbr,tfr &tmfr -total, rural and urban areas-india/states/uts/districts-2007 total 2007 rural 2007 urban 2007 india/states/uts/districts cbr tfr tmfr cbr tfr tmfr cbr tfr tmfr the nilgiris (tn) 13.6 1.5 2.4 13.2 1.4 2.3 14.0 1.5 2.5 dindigul (tn) 14.7 1.7 2.6 14.8 1.7 2.6 14.4 1.6 2.5 karur (tn) 14.2 1.6 2.5 14.3 1.7 2.6 14.0 1.5 2.4 tiruchirappalli (tn) 14.7 1.7 2.7 15.5 1.8 2.9 13.9 1.5 2.5 perambalur (tn) 15.8 1.8 2.8 15.8 1.8 2.8 15.7 1.7 2.7 ariyalur (tn) 16.1 1.9 2.9 16.2 1.9 3.0 15.4 1.7 2.8 cuddalore (tn) 15.8 1.8 2.8 16.5 1.9 3.0 14.6 1.6 2.6 nagapattinam (tn) 15.1 1.7 2.8 15.1 1.7 2.8 15.0 1.7 2.7 thiruvarur (tn) 14.3 1.6 2.6 14.2 1.6 2.6 14.4 1.6 2.5 thanjavur (tn) 14.7 1.6 2.7 15.0 1.7 2.8 14.2 1.5 2.5 pudukkottai (tn) 16.4 1.9 3.0 16.6 1.9 3.1 15.7 1.7 2.8 sivaganga (tn) 15.2 1.7 2.7 15.2 1.8 2.8 15.0 1.7 2.6 madurai (tn) 15.1 1.7 2.7 15.9 1.8 2.9 14.7 1.6 2.5 theni (tn) 14.3 1.6 2.5 14.5 1.7 2.6 14.0 1.6 2.4 virudhunagar (tn) 15.1 1.7 2.7 15.6 1.8 2.9 14.6 1.6 2.5 ramanathapuram (tn) 15.4 1.8 2.7 15.2 1.8 2.7 15.8 1.8 2.8 thoothukkudi (tn) 15.5 1.8 3.0 15.5 1.8 3.1 15.6 1.8 2.8 tirunelveli (tn) 15.4 1.8 2.9 15.9 1.9 3.0 15.0 1.7 2.7 kanniyakumari (tn) 14.2 1.6 2.6 14.6 1.7 2.7 14.1 1.6 2.6 dharmapuri (tn) 16.3 1.9 2.9 16.5 2.0 2.9 15.2 1.7 2.7 krishnagiri (tn) 16.8 2.0 3.0 16.7 2.0 3.0 17.1 1.9 2.9 coimbatore (tn) 13.3 1.5 2.2 12.3 1.4 2.1 13.6 1.5 2.3 krishna murthy, p and ravi kant, s. (mejs) volume 10(1):89-108, 2018 © cncs, mekelle university 108 issn: 2220-184x tiruppur (tn) 13.9 1.5 2.3 12.2 1.4 2.1 15.0 1.6 2.4 puducherry (py) 15.4 1.7 2.8 16.3 1.8 3.0 15.0 1.6 2.7 yanam (py) 16.8 1.9 3.1 na na na 16.8 1.9 3.1 puducherry (py) 15.2 1.7 2.8 16.4 1.8 3.0 14.7 1.6 2.6 mahe (py) 15.5 1.7 2.6 na na na 15.5 1.7 2.6 karaikal (py) 16.0 1.8 3.0 16.2 1.8 3.1 15.8 1.8 2.9 andaman & nicobar islands (an) 15.6 1.8 2.9 16.0 1.9 3.0 14.8 1.7 2.6 nicobars (an) 15.8 2.0 3.5 15.8 2.0 3.5 na na na north & middle andaman (an) 16.5 1.9 3.0 16.6 2.0 3.1 13.3 1.4 2.4 south andaman (an) 15.1 1.7 2.7 15.5 1.8 2.8 14.9 1.7 2.6 source: estimates prepared by the researchers; na: not available; uts: union territories © cncs mekelle university water balance and groundwater quality of koraro area, tigray, northern ethiopia dessie nedaw department of earth science, college of natural and computational sciences, p.o. box 231, mekelle university, mekelle, ethiopia (dessienedaw@yahoo.com) abstract achieving the millennium development goals (mdg) has been given a paramount importance by both regional and federal governments in ethiopia. in this direction some stations in hawzen woreda, tigray regional state, extremely poor, have been selected as model areas to test the achievement of the mdg. this paper focuses koraro tabia (or station), one of the millennium villages where shortage and bad quality water is a challenge. water balance and the hydro chemical characteristics of groundwater have been investigated in order to assess the water potential and quality in the area. hydrometeorological information has been used to calculate water balance parameters and the recharge amount. accordingly, the mean annual rainfall, actual evapotranspiration, bare land evaporation, runoff and groundwater recharge was found to be 548.5 mm, 431.3 mm, 372 mm, 71.33mm and 56.7mm respectively. twelve water samples were collected from hand dug wells and springs located in different lithologies and were tested for major anions, cations, and some trace metals in ethiopian geological surveys central geological laboratory. mean electrical conductivity of water samples from different sources varies significantly. the mean electrical conductivity for the hand dug wells is found to be 5170 µs/cm and that of springs is 209 µs/cm. piper diagram revealed that groundwater in the hand dug wells is of sodium sulfate type and spring water are calcium bicarbonate type. the results indicate that groundwater from the hand dug wells is of very poor quality with high salinity and sulfate content and does not fit for human consumption. therefore, it is recommended to avoid water for drinking purpose from hand dug wells constructed in shale dominated areas and in the alluvial deposits underlain by shale. moreover, groundwater recharge is also insufficient in the area due to the impervious shale unit. hence, an adaptive management method is suggested for efficient use of water and a mechanism to isolate the bad quality water while trying to construct water supply scheme for drinking in the area. key words: groundwater, water balance, water quality, koraro, ethiopia. 1. introduction global fresh water demand is alarmingly increasing with increase in population and civilization. as industrial, agricultural and domestic pollution threaten existing supplies water will become increasingly precious resource. ethiopia surface water and groundwater resources have been regarded as high giving a name to the country as the water tower of east africa (said, 1993). this is factually true when considering half of the country, particularly the western and south western parts of the country. the endowment can be used for productive purpose that can transform the countries socio dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 111 economy (selashi, 2007). unfortunately its uneven distribution in space and time coupled with poor management and development of the resource lead the country to a repeated famine resulting from drought (fao, 2005). the tigray regional state is situated in the northern part of ethiopia, where drought and subsequent famine was common in the past. the study site, koraro tabia which is found in the tekeze basin, is characterized by intermittent rivers which are dry 8 to 9 months with arid and semi arid climatic condition. koraro town is one of the millennium villages which are established in the year 2005. surrounded by an arid landscape and set on eroded soil, the millennium village of koraro, with a population of 55,000 faces an enormous challenge (ngigi, 2009). water availability for domestic use and irrigation was a major obstacle to development, in spite of two rivers running through the cluster of villages. the limited accessible water sources were unsafe for human consumption because of contamination. sixty percent of the hand-dug wells were contaminated. the closest river was 2 to 4 km away from most homesteads. the flow of the streams was seasonal and communities had to rely on groundwater, accessed by scooping sand or digging holes in the dry riverbed. this traditional source often yields unsafe water due to contamination associated with poor sanitation (ngigi, 2009). the water supply for domestic use is entirely dependent on groundwater. both the cattle and human population get water from the available groundwater resource which is not studied systematically. moreover, the community has complained about the taste of water from the existing hand dug wells. these issues are addressed in this paper in terms of quantity and quality of groundwater, recharge from hydrological perspective, and suggest suitable viable options. to meet this objective a systematic study was carried out in the study area to 1) estimate available groundwater recharge using water balance method; 2) make a systematic hydrogeochemical investigation and 3) assess the water quality for drinking and irrigation purposes. 2. description of the study area 2.1 location and accessibility the study area is located in the eastern zone of tigray regional state within tekeze basin (figure 1). it is situated some 27 km south west of hawzen town and covers an area of 58.9 km2. the utm location is between 1530000m-1537000m n to 527000m-533000m e. the area is accessed through dry weather road which runs from hawzen through megab westward. dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 112 figure 1. location map of the study area (filled circle represents a study area). 2.2. topography, drainage, land use and land cover topography expresses the physical features of a surface area including relative elevation and position of natural features. the area is characterized by a highly elevated land mainly composed of sandstone in southeast and east, and a relatively flat and lower elevation portion in the west and northwest (figure 2). the highest and lowest elevation of the area is 2300m above sea level (a.s.l) and 1600m a.s.l, respectively (figure 3). the catchments area has been categorized into study area dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 113 three classes based on slope: area with gentle slope accounts for 40.2%, that of moderately steep (intermediate slope) 43% and steep slope 16.7%. the gentle slope land mostly dominate central part of the study area while, the steep and moderately steep slopes dominate the eastern and some part of the western area. figure 2. digital elevation model of the study area. figure 3. west east topographic cross section of the study area. the area portrays a dendritic drainage pattern with drainage density of 3 km/km2 (figure 4). the seasonal stream named as tewulah has tributaries such as tenseka, dagbatat, af tsebib. dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 114 land use is the manner in which human beings employ the land and resources. the land use and land cover of the area is grouped in to four divisions, namely cultivated about 43 %, bushes and shrubs about 39%, bare land about 16% and settlement 2%. figure 4. drainage pattern of the study area. 2.3 geological and hydrogeological setting the major lithological units in the study area are metavolcanics, tillites, sandstones and recent deposits (alluvial and colluvial). stratigraphicaly, metavolcanic rocks are found at the base overlain by edegarbi tillites and enticho sandstones. moreover recent quaternary deposits with variable thickness are found overlying all these successions in the lowlands (figure 5). 2.3.1 metavolcanic rocks the metvolcanic rocks cover most of the western half of the study area (41% of the surface area). the rocks are characterized by mafic composition with foliations, joints and fractures. these structural features facilitate recharge to the groundwater system in the area. the hydrogeological significance of this rock is mainly concentrated on areas which are highly weathered and with dense fracturing. 2.3.2 tillites dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 115 the glacial deposit in the area is characterized by fine materials ranging from clay to silt with imbedded boulders. they are found in contact with the metavolcanics as small patches. this deposit accounts for 4% of the mapped area in the northeastern and southwestern parts. because of the nature of the depositional environment the rocks are poorly sorted. its significance as aquifer is low because of its low permeability but act as an aquitard as evidenced by the contact springs. 2.3.3 sandstones this formation is mostly found at the mountainous area overlying the glacial deposit or the metavolcanics. sandstone accounts for 20% of the mapped area and are found mainly on the eastern part of the area. sandstones are characterized by reddish colure and cliff formation. the grain size ranges from fine to medium and are highly compacted. the sandstones are highly fractured and in some cases with a primary porosity. most of the springs in the area emerge at the contact of the sandstone with the underlying tillite or metavolcanic rocks. hydrogeologically the sandstones are the main recharge area for the springs developed for water supply in koraro tabia. 2.3.4 recent deposits (quaternary deposits) this unit occupied flat to gentle land and the deposits are transported from the surrounding hills by gravity and fluvial processes. alluvial deposits are restricted to low lying areas close to river course. the sediments are made of clay and silt and, quartz rich sand with variable thickness. this unit covers most part of the central area with coverage of 35%. in some instances these deposits are found overlying layered thin siltstone, clay stone, thick mudstone intercalated with gypsum. the mudstones are largely exposed in the southwestern part of the study area which is around the newly established koraro town. hydrogeologically both the location and the lithology favors for groundwater resource development using shallow wells. consequently, most of the hand dug wells are located in this area. the koraro village lies on glacial sediments which consist of mudstones and shales with some granite boulders exposed at places (plate 1). and it is surrounded by rocks of metamorphic varieties towards the north and northwest; there are erosion remnants of sandstones on south and south east of the village. dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 116 plate 1. photograph showing the lithologies present in and around koraro village. figure 5. geological map and water sample location. 3. methodology to achieve the above mentioned objective a desk work has been conducted on the available information, topographic maps, areal photographs and digital elevation model. moreover, hydrometeorological data have been collected and analyzed to estimate groundwater recharge. glacial sediments / koraro village sandstone basement rocks (metavolcanics & h llit ) dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 117 the potential evapotranspiration from vegetation covered area is estimated using thornthwaite method where as the evaporation from bare soil is estimated by taking 20% of evaporation calculated using the penman method. the actual evapotranspiration is calculated by applying the thornthwaite and mather method. the runoff is estimated using the rational method. the groundwater recharge is calculated by applying the soil moisture water balance method. field measurement has been conducted on ph, electrical conductivity and total dissolved solids. twelve water samples were collected and analyzed for major ions and some trace metals at the geological survey laboratory, addis ababa. to verify accuracy of the analytical results duplicate samples were also collected from the same sample site and given to the laboratory. the chemical data thus obtained was processed using aquachem, arcview and other relevant software. 4. results and discussion 4.1 water balance in order to estimate the water balance of a given hydrological basin each of the hydrometeorological elements has been quantified. accordingly, rainfall, actual evapotranspiration, runoff and groundwater recharge have been estimated. 4.1.1 rainfall in order to analyze the rainfall condition of the area sixteen years data were collected from hawzen meteorological station (1992 – 2007). accordingly, the total annual rainfall of the area was estimated to be 548.5mm (table 1). the dry season are observed from september to june whereas the rainy seasons extend from june to september. a small rainy season is observed in otherwise dry season on the months of april and may. 4.1.2. actual evapotranspiration in order to calculate the actual evapotranspiration, other meteorological elements such as temperature, humidity, wind speed and sunshine hours have been analyzed. dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 118 4.1.2.1. temperature and humidity six years temperature data were considered (2002-2007) for hawzen station. accordingly, the lowest mean monthly temperature (14.5 °c) is recorded in january and the highest mean monthly temperature is recorded in may (20.6 °c) (table 1). the moisture content of air expressed in weight per unit of volume is called the absolute humidity. relative humidity is used to characterize the area. looking the values tabulated below the area is mainly characterized by a dry air except july and august (table 1) 4.1.2.2. wind speed wind speed has a strong influence on the rate of evaporation, and evapotranspiration. the wind speed from the mekelle air port meteorological station has been used to evaluate the bare soil evaporation. the 12 year data of wind has been averaged as follows (table 1). 4.1.2.3. sunshine hour sunshine hour has a direct relationship with the solar radiation received on a certain area which in return has an impact on daily evaporation. the sunshine hours as recorded from mekelle station has been presented in table 1. table 1. monthly meteorological elements used for water balance calculation. 4.1.2.4. evapotranspiration (et) from vegetation covered area for the study area, potential evapotranspiration rate was evaluated using the thornthwaite method. the mean monthly gross potential evapotranspiration is calculated for the basin (table 2). monthly variation of potential evapotranspiration (pet) indicates variation in monthly air temperature. as it can be seen from the table, highest monthly value of pet in the catchment area generally come just before the onset of rainy season. based on this method the mean annual pet of the study area is 813 mm (table 2). month jan feb mar apr may jun july aug sept oct nov dec rainfall (mm) 4 3.7 23.4 35.9 30.7 42.6 160.6 188.3 32.3 12.9 9.7 4.4 mean temp (oc) 14.5 17 20 20 20.6 20.2 18 17.8 17.5 17 16.8 16.3 r.h (%) 43.8 38.2 39.7 39.8 37.1 39.8 68.6 74.3 49.5 42.9 44.7 42.5 wind speed (m/s) 3.6 4.2 5.3 3.9 3 2.3 1.9 1.7 1.8 3.1 3.5 3.7 daily sunshine hour 9.67 9.9 8.2 9.1 9.73 7.2 5.5 5.3 7 9.6 9.9 9.7 dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 119 table 2. estimated potential evapotranspiration in the study area. jan feb mar apr may jun july aug sept oct nov dec temperature 14.5 17 20 20 20.6 20.2 18 17.8 17.5 17 16.8 16.3 pet 45 60 80 80 85 82 66 65 63 60 59 55 latitude correction 0.94 0.97 1.00 1.04 1.07 1.08 1.08 1.05 1.02 0.98 0.95 0.93 corrected pet 42.3 58.2 80 83.2 90.95 88.56 71.28 68.25 64.26 58.8 56.05 51.15 the actual evapotranspiration is computed from the pet, precipitation and the soil moisture availability as presented by thorentwaite and mather (thorenthwaite and mather, 1957). the soil moisture availability is calculated from accumulated potential water loss and available water capacity. the available water capacity (awc) has been computed from the vegetation type and soil type. accordingly, the following combination of land cover and soil type has been recognized. sandy loam with cereal crops with area coverage of 14.51 km2, fine sand with cereals 10.79 km2, bush and shrub with fine sand with an area of 22.93 km2. each combination has awc value of 150, 75 and 100 respectively. accordingly, the actual evapotranspiration of each land cover and soil type combination is calculated (table 3). considering all the land cover type and taking the weighted mean of the actual evapotranspiration in proportion to the area coverage the actual evapotranspiration has been found to be 431.3 mm per year for the vegetation covered area. table 3.estimated actual evapotranspiration for the different land use and soil type combinations. 4.1.2.6 evaporation from bare land and settlement area the evaporation from the bare land and settlement which accounts for 18% of the surface area coverage has been calculated using penman method (penman, 1948). twenty percent of the penman evaporation has been assumed to be the evaporation rate considering the lower amount of precipitation (548.5 mm/year) and a higher rate of runoff in the area (71.33 mm/year). accordingly the evaporation from these areas has been assumed to be 0.2 *1860 mm = 372 mm per year. month jan feb mar apr may jun jul aug sep oct nov decannual area coverage(km2) aet for awc of 150 15 15 31 41 35 45 70 68 61 45 33 22 481 14.51 aet for awc of 75 7 6 24 36 31 43 70 68 59 36 22 11 412 10.79 aet for awc 100 10 9 26 37 32 43 70 68 60 40 27 15 437 22.93 dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 120 4.1.3 runoff estimating runoff from rain fall measurement is very much dependent on the time scale being considered. due to absence of flow data in the area, the volume of runoff was determined by use of runoff coefficient method. value of runoff coefficient for different types of land use is used in the calculation of runoff coefficient for the study area. the runoff coefficient (c ) of the koraro catchments with an area of 58.9 km2 is determined to be 0.13. accordingly the runoff has been found out to be 4.2mcm = (71.33 mm/year). 4.1.4 water balance calculation water balance, is the relationship between the inflow water from precipitation and the out flow of water by evapotranspiration, groundwater recharge and stream flow. in the study area, the soil moisture water balance method has been used for the estimation of the natural ground water recharge of the area. since the calculation is made on annual bases, net change in soil moisture storage is assumed to be zero. moreover subsurface water exchange with neighboring basins is assumed to be zero. hence the water balance equation for the catchments area is simplified as follows. p = aet + e + i +q ---------------------------(4.1) where p: mean annual precipitation on the basin; e: evaporation from the bare land and settlement aet: mean annual actual evapotranspiration from the basin q: mean annual run off from the basin i: infiltration (recharge) from the above budget equation the amount of water that infiltrate in to the catchment area as a ground water accretion was calculated. i = p-(aet + e+q) ------------------------------(4.2) i = 548.7mm/yr – ((431.3mm/yr*0.82)+(372 mm/yr *0.18)+( + 71.33mm/yr)) = 56.7 mm/yr from the above calculation the safe yield of the basin can be assumed to be 50 percent of the total estimated recharge which is 28.35mm/year or 1.67 mcm. therefore, 1.67 mcm of groundwater can be safely abstracted with out adversely affecting the system. dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 121 4.2 hydrochemistry 4.2.1 accuracy of chemical analysis result a total of 12 samples including the duplicates; kow1, kodssp1, kow2, kow4, kodsw2, kow3, bs2 from hand dug wells, kosp1. kosp2, kosp3, bs1 from springs and kodsw1 from river bed were collected from the study area on 3/14/2009 (figure 6 and tables 4, 5 & 6). to evaluate the accuracy of the chemical analysis results three methods were used. first the values of the blind samples are compared to their twin. the error was found to be 0.02% and 0.08%. secondly the balance between cations and anions measured by the electro neutrality has been examined and it has shown a value of less than 5 for 75 % of the samples the average neutrality value was found to be 4.1 %. ( ) ( ) 100⋅ + − = sumanionssumcations sumanionssumcations neutralityelectrol ............(4.3) third technique used to check accuracy of chemical analysis is to compare calculated conductivity with measured electrical conductivity (ec) with the following relationship (c.a.j. appelo et.al, 1996). )/(100/)/( cmseclmeqcationsanions µ==∑ ∑ .................(4.4) the error ranges from 0.006 % to 0.18%. accordingly, the chemical analysis result was found to be good so further interpretation has been conducted from the analysis result. 4.2.2 general characteristics of the water samples from the study area the field ph for the samples ranges from 6.89 in kosp3 to 9.14 in kodsw2 with an average ph value of 7.6. 4.2.2.1 water samples from the hand dug wells out of the 12 samples seven of them were collected from the area which is covered by thin quaternary alluvial deposits underlain by the tillite intercalated with marl and shale. these samples are collected both from existing hand dug wells and shallow wells which are dug for the purpose of this investigation (table 4.). the major geologic materials exposed in the wells are shale and marl units overlain by alluvial deposits. the electrical conductivity (ec) of most samples is more than 3000 µs/cm which makes them to be grouped as brackish water. in general, the samples were found to be dominated by sodium, sulfate and chloride (table 4, and figure 6). dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 122 the ec value ranges from 2650 µs/cm in kodsw2 to 6970 µs/cm in kow1 with an average of 5170 µs/cm (table 4). among the cations the dominant element is sodium which ranges from 530 mg/l in kodssp1 to 1280 mg/l in kow2 with an average concentration of 786 mg/l. the next dominant cation is calcium followed by magnesium. the range of calcium is from 5 mg/l in kodsw2 to 370 mg/l in kow1 and that of magnesium is from 0.9 mg/l in kodsw2 to 360 mg/l in kow1. the average concentration of ca+2 was found to be 176 mg/l where as that of mg+2 was found to be 167 mg/l. potassium ranges from 3 mg/l to 14 mg/l with an average concentration of 5.2 mg/l. iron manganese, zinc and aluminum were also measured but their concentration was found to be insignificant. among the anions the dominant ion was found to be sulfate which ranges from 101 mg/l in (kodsw2) to 2671 mg/l in (kow1), with an average concentration of 1424 mg/l. the next dominant anion is bicarbonate which ranges from 305 mg/l in kow1 to 1149 mg/l in kodsw2 with an average concentration of 732 mg/l. chloride is the third dominant anion in the area ranging from 137 mg/l in kodsw2 to 929 mg/l in kow1 with an average concentration of 637 mg/l. next to chloride the dominant anion was found to be nitrate which ranges from 0.4 mg/l in kow4 to 35 mg/l in kow1. 4.2.2.2 samples from springs four water samples were collected from springs which emerge out from the sandstone formation which make up the cliffs in the south eastern parts of the study area. the samples are namely kosp1, kosp2, kosp3, and bs1 (table 5). the ec of all the samples in this terrain are less than 300 µs/cm indicating the water to be fresh in contrast to the other groups of water. the ec ranges from 170 µs/cm in kosp1 to 256 µs/cm in kosp2 with an average value of 209 µs/cm. the samples were found to be calcium bicarbonate type (table 5 and figure 6). the dominant cation is calcium and the concentration ranges from 21 mg/l in kosp1 to 33 mg/l in kosp3. next to calcium, sodium is found to be abundant ranging in value from 6 mg/l in kosp1 to 9 mg/l in kosp3. among the anions bicarbonate (hco3) was found to be the most abundant and ranges in concentration from 61 mg/l in kosp1 to 107 mg/l in kosp2 with an average concentration of 83.5 mg/l. next to bicarbonate, sulfate was found to be abundant and ranges from 14 mg/l in kosp1 to 34 mg/l in kosp2 with an average concentration of 22 mg/l. next to sulfate, chloride was found to be dominant with a concentration ranging from 12 mg/l in kosp1 dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 123 to 15 mg/l in kosp2 with an average concentration of 14 mg/l. next to chloride the dominant anion was found to be nitrate it ranges from 1.4 mg/l in kosp2 to 3.5 mg/ l in kosp1. 4.2.2.3 water sample collected from a river bed sand deposit one sample has been collected from the alluvial cover in a river bed in tewlah river. the sample is labeled as kodsw1 (table 6). the electrical conductivity of this sample was found to be 952 mg/l. the most abundant cation was found to be calcium with 110 mg/l next to calcium, sodium was found to be most abundant with 50 mg/l. the most abundant anion was found to be hco3 with a concentration of 295 mg/l followed by sulfate with a concentration of 107 mg/l. 4.2.3 total hardness of the water samples analytical hardness is calculated using the following formula: mgcah 1.45.2 += --(4.5) accordingly the hardness was found to range from 470 to 2406 in the hand dug wells and from 64.8 to 107.12 in the springs. there is a clear distinction of the water samples from the hand dug well and the springs. figure 6. piper plot for water samples a) hand dug well, b) spring samples. dessie, n (mejs) volume 2 (2):110-127, 2010 © cncs mekelle university 124 sample id type utme utmn ph ec tds na k ca mg f cl b hco3 no3 so4 sio2 m m us/cm mg/l bs2 na-mg-ca-so4-cl 527646 1532585 7.68 7040 5630 830 3 380 390 1.2 944 <0.17 329 36 2666 25 kodssp1 na-mg-so4-cl 527630 1533202 7.93 4270 3230 530 14 130 170 1.3 563 4.1 468 0.16 1311 19 kodsw2 na-hco3 524675 1529716 9.14 2650 2173 575 2 5 0.9 9.5 137 0.68 1149 <0.04 101 36 kow2 na-so4-cl-hco3 528517 1533677 7.17 6630 5058 1280 3 110 110 1.3 797 1.2 1000 14 1673 34 kow1 na-mg-ca-so4-cl 527646 1532585 7.71 6970 5536 810 3 370 360 1.2 929 0.77 305 35.4 2671 25 kow3 na-so4-hco3-cl 530409 1535405 8.13 3680 2839 660 3 40 90 4.1 335 8.7 864 0.53 795 19 kow4 na-cl-hco3-so4 529469 1533245 7.35 4950 3659 820 6.2 200 50 0.53 755 4.5 1013 0.41 749 30 average 7.87 5170 4018 786.4 4.9 176 167 2.73 637 3.325 732.6 14.42 1424 26.9 table 4. chemical analysis results and water types of samples collected from hand dug wells. sample id water type utme utmn ph ec tds na k ca mg f cl b hco3 no3 so4 sio2 m m us/cm mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l mg/l bs1 ca-hco3-cl 529160 1532221 7.16 170 144.41 6 1 21 3.4 0.14 15 <0.17 61 3.5 13 10 kosp1 ca-hco3-cl 529160 1532221 7.07 169 142.61 6 0.6 21 3 0.14 12 <0.17 62 3.5 14 10 kosp2 ca-hco3-so4 528328 1529731 7.35 239 223.02 7 2 32 4 0.23 15 <0.17 107 1.4 34 8 kosp3 ca-hco3-so4 529810 1531505 6.89 256 223.02 9 3 33 6 0.25 15 <0.17 104 2.4 28 11 average 7.1 209 183.3 7 1.7 27 4.1 0.2 14 83.5 2.7 22 9.8 table 5. chemical analysis results and water types of samples collected from springs. sample id water type utme utmn ph ec tds na k ca mg f cl b hco3 no3 so4 sio2 m m us/cm mg/l mg/l kodsw1 ca-na-mghco3-cl-so4 529537 1535253 7.64 952 713.77 50 3 110 24 1.3 83 <0.17 295 4.1 107 18 table 6. chemical analysis result and water type of sample collected from river bed sand. © cncs mekelle university 125 4.3 water quality 4.3.1 drinking water quality in general, the spring water samples have excellent quality where as the hand dug wells have very poor quality as per the world health organization recommendation. in the hand dug wells boron ranges from 0.68 mg/l to 8.7 mg/l which is well beyond the recommended value 0.3 mg/l mowr (2002). long term exposure to high boron concentration will lead to gastrointestinal irritation. chloride is found to be more than the guideline value, 533 mg/l in most of the hand dug wells resulting in undesirable test. sodium concentration in the hand dug well ranges from 530 mg/l to 1280 mg/l. the guideline value of mowr is 358 mg/l. therefore the concentration is way beyond the standard. high sodium in general results undesirable taste. sulphate in the hand dug well ranges from 795 mg/l to 2671 mg/l this is much higher than the guideline value which is 483 mg/l. normally high sulphate concentration results in noticeable taste. 4.3.2 irrigation water quality the concentration and composition of dissolved constituents in water determine its quality for irrigation use. the characteristics of an irrigation water that appear to be most important in determining its quality are: (1) total concentration of soluble salts (2) relative proportion of sodium to other cations (3) concentration of boron or other elements that may be toxic (united states salinity laboratory staff, 1954). the effect of total dissolved solids could be safely appraised using electrical conductivity. accordingly, water with less than 750 µs/cm is satisfactory for irrigation, waters in ranges of 750 µs/cm to 2250 µs/cm are widely used, and satisfactory crop growth is obtained under good management and favourable drainage conditions, but saline conditions will develop if leaching and drainage are inadequate. use of waters with conductivity values > 2,250 µs/cm is the exception and very few instances can be cited where such waters have been used successfully used (united states salinity laboratory staff, 1954). the conductivity of the waters in the hand dug well ranges from 2650 µs/cm to 6970 µs/cm. therefore, the hand dug wells were found unsuitable for irrigation purpose. sodium occurs in almost all irrigation water. it is the most injurious of the major cations. the danger of high sodium water in irrigation agriculture is examined using sodium adsorption ratio (sar). sar value between 2 and 10 indicates little danger from sodium; between 7 and 18 medium hazard; highly hazardous between 11 and 26 and very highly hazardous above 26 © cncs mekelle university 126 (fetter, 2001). most of the hand dug wells has a sar value greater than 11 coupled with high salinity. this make the water in most of the hand dug well to be highly hazardous. boron is a constituent of practically all natural waters, the concentration varying from traces to several parts per million. it is essential to plant growth, but exceedingly toxic at concentrations only slightly above optimum. in the study area, most of the hand dug wells were found to have a concentration above 1ppm indicating to be the waters highly hazardous. 4.3.3. classification of irrigation waters the irrigation water classification of samples in the us salinity laboratory diagram is given in the following figure (wilcox, 1955). all the hand dug wells are found to be very high salinity and very high sodium water which renders them to be unsuitable for irrigation. the spring waters are excellent for irrigation (figure 7). figure 7. wilcox diagram for irrigation water classification, koraro area (note: electrical conductivity of some samples which were more than 5000 µs/cm has been reduced to 5000 µs/cm only for the purpose of plotting. 5. conclusions as per the finding of this work, the groundwater recharge is low. it accounts only 10% of the precipitation. this is mainly because of the high evapotranspiration rate, and low permeability of © cncs mekelle university 127 the surface materials associated with high temperature and lower humidity. the groundwater quality from the hand dug wells dug in the shale are extremely poor both for drinking and irrigation purpose where as that of springs is excellent. the development of the koraro village as a successful millennium village depends completely on the wise utilisation of the existing water in a more efficient way. therefore, one should make every effort possible to increase the groundwater recharge through different artificial recharge mechanism. moreover groundwater development should avoid the shale unit as much as possible when water is sought for drinking or irrigation. the subsurface and sand storage dam constructed is a good example of both increasing the recharge and avoiding the bad quality water. 6. references appelo, c.a.j & postma, d. 1996. geochemistry, groundwater and pollution, a.a, balkema, rotterdam. fao. 2005. fao’s information system for water and agriculture (aquastat), http://www.fao.org/nr/water/aquastat/countries/ethiopia/index.stm fetter, c. w. 2001. applied hydrogeology. prentice-hall, inc. upper saddle river, new jersey. mowr. 2002. ethiopian guideline specification for drinking water quality. ministry of water resource, addis ababa. penman, h.l. 1948. natural evaporation from open water, soil and grass. proceedings of the royal society of london, series a, 193:120-145. said, r. 1993. the river nile, geology, hydrology and utilisation, pergamon press, uk, 282p. seleshi, b. 2007. water challenges, innovations and interventions for ethiopia, think tank paper on water resource (unpubl). stephen nigigi. 2009. http://blogs.millenniumpromise.org/index.php/2009/09/14/koraroinnovative-projects-for-a-better-use-of-precious-water/. thornthwaite, c. w & mather, j. k. 1957. instructions and tables for computing potential evapotranspiration and the water balance. publ. in climatology, new jersey, vx (3), 185-311. united states salinity laboratory staff. 1954. diagnosis and improvement of saline and alkali soils, u.s.d.a., agricultural handbook no. 60pp. wilcox, l.v. 1955. classification and use of irrigation waters. u.s. dept. agri., cir. 969, 19pp. microsoft word 1. front cover page with issn nos characterization of distributive and standard ideals in semilattices rama ravi kumar,e.s.,1* venkateswara rao, j2 and srinivas kumar, v3 1*department of mathematics, v. r. siddhartha engineering college, vijayawada, a.p., india (*srrkemani@yahoo.co.in) 2 department of mathematics, college of natural and computational sciences, p. o. box 231, mekelle university, mekelle, ethiopia (venkatjonnalagadda@yahoo.co.in) 3department of mathematics, j.n.t.u.h, college of engineering, j.n.t.u., kukutpally, hyderabad 500 085, a.p., india (srinu_vajha@yahoo.co.in) abstract this paper investigates the concepts of distributive ideal, dually distributive ideal and standard ideal in a join semilattice. it concerns with the property of ideals in a distributive semilattice. we obtain a characterization theorem for distributive (dually distributive) and standard ideal in a join semilattice. we establish the necessary and sufficient condition for a distributive ideal to be standard ideal. finally, we bear out the fundamental theorem of homomorphism and isomorphism theorem of standard ideal. keywords: distributive ideal, distributive semilattice, dually distributive ideal, standard ideal, join semi lattice. [ams subject classification (2000): 06a12, 06a06, a6b99)] 1. introduction the concept of distributive ideal, standard ideal and neutral ideal in a lattice l has been introduced and studied by hashimoto (1952); and gratzer and schmidt (1961). properties of distributive ideals of birkhoff (1967) are considered in our work. in this paper we studied the notion of distributive (dually) ideal and standard ideal in a semilattice of gratzer (1978) and produced a characterization theorem of standard ideal. the necessary and sufficient condition for a distributive ideal to be standard ideal was produced. finally, the fundamental theorem of homomorphism and isomorphism theorem of standard ideal were proved. 2. methodology hashimoto (1952) and gratzer and schmidt (1961) have defined standard and distributive ideal and standard and distributive element in a lattice l and an example of standard ideal as a principal ideal. also, they afforded a result that if “s” is a standard element and if “a” is an arbitrary element of lattice, then a s is a standard element of the principal ideal (a] and this result is not valid for distributive elements. the properties of distributive ideals birkhoff (1967) were considered for our work and we investigated the notion of distributive (dually) ideal, © cncs, mekelle university issn:2220-184x mailto:srrkemani@yahoo.co.in mailto:venkatjonnalagadda@yahoo.co.in http://in.mc83.mail.yahoo.com/mc/compose?to=srinu_vajha@yahoo.co.in rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 standard ideal in a semilattice of gratzer (1978) and produced a characterization theorem of standard ideal. we established the necessary and sufficient condition for a distributive ideal to be standard ideal. finally, we obtained the fundamental theorem of homomorphism and isomorphism theorem of standard ideal. 3. distributive ideals 3.1. definition a semilattice is a partially ordered set (s, ≤) in which any two elements in s have the least upper bound in s. 3.2. definition a semilattice is a non empty set s with binary operation ∨ defined on it and satisfies the following: idempotent law : a ∨ a = a for all a in s, commutative law : a ∨ b = b∨a for all a, b in s, associative law : a∨ (b∨ c) = (a ∨ b) ∨ c for all a,b,c in s. 3.3. theorem in a semilattice s, define a ≤ b if and only if a ∨ b = b for all a, b in s. then (s, ≤) is an ordered set in which every elements has a least upper bound, conversely, given an ordered set p with that property, define a ∨ b = l.u.b.(a, b). then (p, ≤) is a semilattice. 3.4. definition a non empty subset d of a semilattice s is called an ideal if (i) for x in d, y in d ⇒ x ∨ y in d , (ii) for x in d, t in s and t ≤ x ⇒ t in d. 3.5. theorem if i(s) denotes the set of all ideals of a semilattice s, then i(s) is a lattice with respective to the following: (i) d1≤ d2 if and only if d1 ⊆ d2 © cncs, mekelle university issn:2220-184x 21 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 (ii) d1 ∨ d2 = { x in s / x = x1 ∨ x2 , where x1 is in d1, x2 is in d2} (iii) d1 ∧ d2 = {x in s / x is in d1 and x is in d2}; where d1, d2 are in i(s). 3. 6. definition the smallest ideal containing x in s is denoted by (x] and is given by (x] = { s in s / s ≤ x}. such ideal is called principal ideal generated by x. 3.7. definition an ideal d of a semilattice s is called distributive ideal if and only if d ∨ (x ∧ y) = (d ∨ x) ∧ (d ∨ y) for all x, y in i(s). 3.8. definition an ideal d of semilattice s is called dually distributive ideal if and only if d ∧ (x ∨ y) = (d ∧ x) ∨ (d ∧ y) for all x, y in i(s). 3.9. remark the following example shows that an ideal need not be a distributive or dually distributive. consider the semilattice s = {1,a,b,c,an ……, a1,a0 } given in figure 1. o o c o oo o a0 1 b a figure 1. semilattice ideal need not be a distributive (dually distributive). clearly d={ a0, a1….. an,a}, x={ a0, a1….. an,b}, and y={ a0, a1….. an,c} are ideals of s. now x ∧ y = {a0, a1…….. an} , d ∨ (x ∧ y) = {a0, a1…….. an, a}, d ∨ x = s and d ∨ y = s. therefore (d ∨ x) ∧ ( d ∨ y) = s and (d ∨ x) ∧ ( d ∨ y) ≠ d ∨ (x ∧ y). hence d is not a distributive ideal of the semilattice s. o a1 an © cncs, mekelle university issn:2220-184x 22 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 also x ∨ y = s , d ∧ (x ∨ y) = {a0, a1…….. an, a}, d ∧ x = {a0, a1…….. an}, d ∧ y = {a0, a1…….. an} and (d ∧ x) ∨ (d ∧ y) = {a0, a1…. an}. therefore d ∧ (x ∨ y) ≠ (d ∧ x) ∨ (d ∧ y) hence d is not a dually distributive ideal of the semilattice s. 3.10. result if d1 and d2 are distributive ideals then d1 ∨ d2 is also distributive. 3.10.1. proof : let d1 and d2 are distributive ideals of s. then for any two ideals x and y of s, (d1 ∨ d2 ) ∨ ( x ∧ y) = d1 ∨ (d2 ∨ (x ∧ y)) = d1 ∨ [(d2 ∨ x) ∧ (d2 ∨ y)] (as d2 is distributive) = [(d1 ∨ (d2 ∨ x)] ∧ [d1 ∨ (d2 ∨ y)] (as d2 is distributive) = [(d1 ∨ d2) ∨ x] ∧ [(d1 ∨ d2 )∨ y] therefore d1 ∨ d2 is a distributive ideal. 3.11. definition a semilattice s is said to be directed below if a, b ∈ s, then there exists c such that c ≤ a, c ≤ b. 3.12. definition a semilattice s is called distributive if and only if w ≤ a ∨ b, where w, a, b in s ⇒ there exists x, y in s such that x ≤ a, y ≤ b and w = x ∨ y. 3.13. theorem a semilattice s is distributive if and only if (i) s is directed below. (ii) the lattice i(s) of all ideals of s is a distributive lattice. 3.13.1. proof : suppose a semilattice s is distributive. (i) to prove that s is directed below: © cncs, mekelle university issn:2220-184x 23 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 let a, b are in s. then a ∨ b ∈ s. since a ≤ a ∨ b and s is distributive there exists x, y in s such that x ≤ a, y ≤ b and a = x ∨ y.trivially y ≤ x ∨ y = a. therefore for a, b in s there exists y in s such that y ≤ a, y ≤ b so that s is directed below. (ii) to prove that the lattice i(s) is distributive: now x ∨ y ∈ d1 ∨ (d2 ∧ d3) ⇔ x ∈ d1, y ∈ (d2 ∧ d3) ⇔ x ∈ d1, y ∈ d2 and y ∈ d3 ⇔ x ∈ d1 , y ∈ d2 and x ∈ d1 , y ∈ d3 ⇔ x ∨ y ∈ d1 ∨ d2 and x ∨ y ∈ d1 ∨ d3 ⇔ x ∨ y ∈ (d1 ∨ d2) ∧ ( d1 ∨ d3). therefore d1 ∨ ( d2 ∧ d3) = (d1 ∨ d2) ∧ (d1 ∨ d3). also x ∨ y ∈ (d1 ∧ d2) ∨ (d1 ∧ d3) ⇔ x ∈ d1 ∧ d2 , y ∈ d1 ∧ d3 ⇔ x ∈ d1 and x ∈ d2 , y ∈ d1 and y ∈ d3 ⇔ x ∈ d1 , y ∈ d1 and x ∈ d2 , y ∈ d3 ⇔ x ∨ y ∈ d1 and x ∨ y ∈ d2 ∨ d3 ⇔ x ∨ y ∈ d1 ∧ ( d2 ∨ d3). therefore d1 ∧ ( d2 ∨ d3) = (d1 ∧ d2) ∨ (d1 ∧ d3) and i(s) is a distributive lattice. conversely, suppose that s is directed below and i(s) is distributive lattice. let w ≤ a ∨ b where a, b, w ∈ s. now (w] = (w] ∧ ((a] ∨ (b])= ((w] ∧ (a]) ∨ ((w] ∧ (b]) = a0 ∨ a1,where a0 ∈ (a], a1 ∈ (b]. hence there exists a0, a1 in s such that a0 ≤ a; a1 ≤ b and (w] = a0 ∨ a1. therefore s is distributive semilattice. 3.14. definition a binary relation θ on a lattice l is called congruence relation if (i) θ is reflexive : x ≡ x (θ) for all x in l (ii) θ is symmetric : x ≡ y (θ) ⇒ y ≡ x (θ) for all x, y in l (iii) θ is transitive : x ≡ y(θ) and y ≡ z(θ) ⇒ x ≡ z(θ) for all x, y, z in l (iv) θ satisfies substitution property : x ≡ x1(θ) and y ≡ y1(θ) ⇒ x ∨ y ≡ x1 ∨ y1(θ) and x ∧ y ≡ x1 ∧ y1 (θ) for all x, y, x1, y1 in l. 3.15. theorem let d be an ideal of semilattice s. then the following conditions are equivalent. © cncs, mekelle university issn:2220-184x 24 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 (i) d is distributive. (ii) the map ϕ : x → d ∨ x is a homomorphism of i(s) onto [d) = {x in i(s) / x ≥ d}. (iii) the binary relation θd on i(s) is defined by x ≡ y (θd) if and only if d ∨ x = d ∨ y,, where x, y in i(s) is a congruence relation. 3.15.1. proof: let d be an ideal of semilattice s. to prove that (i) ⇒ (ii): suppose (i) holds. then d∨ (x ∧y) = (d ∨ x) ∧ (d ∨ y) for all x, y in i(s) define a map ϕ : x → d ∨ x by ϕ (x) = d ∨ x. → (1) for x, y in i(s), ϕ ( x ∨ y) = d ∨ (x ∨ y) = (d ∨ d) ∨ (x ∨ y) = d ∨ [d ∨ (x ∨ y)] = d ∨ [d ∨ x ∨ y] = d ∨ (d ∨ x) ∨ y)] = (d ∨ x) ∨ (d ∨ y) = ϕ (x) ∨ ϕ (y). similarly, ϕ (x ∧ y) = d ∨ (x ∧y) = (d ∨ x) ∧ (d ∨ y) = ϕ (x) ∧ ϕ (y). therefore ϕ is homomorphism. next let x in [d). then x ≥ d so that ϕ (x) = d ∨ x = x. therefore for any x in [d), there exists x in i(s) such that ϕ (x) = x so that ϕ is homomorphism of i(s) onto [d). to prove (ii) ⇒ (iii): suppose the map ϕ: x → d ∨ x is a homomorphism of i(s) onto [d) = { x in i(s) / x ≥ d}.define the binary relation θd in i(s) as x ≡ y (θd) if and only if d ∨ x = d ∨ y where x, y in i(s). we shall show that the relation is congruence: (a) for any x in i(s), d ∨ x = d ∨ x trivially so that x ≡ x (θd) for all x in i(s). therefore θd is reflexive. (b) for x, y in i(s), x ≡ y (θd) ⇒ d ∨ x = d ∨ y ⇒ d ∨ y = d ∨ x ⇒ y ≡ x (θd). therefore θd is symmetry. (c) for x, y, z in i(s), x ≡ y (θd) and y ≡ z (θd) ⇒ d ∨ x = d ∨ y and d ∨ y = d ∨ z ⇒ d ∨ x = d ∨ z ⇒ x ≡ z (θd). therefore θd is transitive. (d) substitution property: suppose x ≡ x1 (θd) and y ≡ y1 (θd) for x, y, x1, y1 in i(s). then d ∨ x = d ∨ x1 and d ∨ y = d ∨ y1. → (2) © cncs, mekelle university issn:2220-184x 25 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 βy (1) and (2) and since ϕ is a homomorphism, d ∨ (x ∨ y) = ϕ (x∨ y) = ϕ (x) ∨ ϕ (y) , = (d ∨ x ) ∨ (d ∨ y ) = (d ∨x1 ) ∨ (d ∨ y1 ) = ϕ (x1) ∨ ϕ (y1) = ϕ (x1∨ y1) = d ∨ (x1 ∨ y1). therefore x ∨ y ≡ (x1 ∨ y1)θd . similarly we can prove that x ∧ y ≡ (x1 ∧ y1)θd. therefore θd is a congruence relation. to show that (iii) ⇒ (i): suppose the binary relation θd defined by x ≡ y (θd) if and only if d ∨ x = d ∨ y is a congruence relation. for x, y in i(s), d ∨ (d ∨ x) = (d ∨ d) ∨ x = d ∨ x ⇒ d ∨ x ≡ x (θd) ⇒ x ≡ d ∨ x (θd) by symmetry. similarly we can prove y ≡ d ∨ y (θd). then by substitution property x ∧ y ≡ [ ( d ∨ x) ∧ ( d ∨ y)] (θd). hence d ∨ ( x ∧ y) = d ∨ (d ∨ x) ∧ (d ∨ y) = (d ∨ x) ∧ (d ∨ y). therefore d is distributive. 3.16. result let d be an ideal of semilattice s. then by applying the principle of duality to 2.15 we can have the equivalence of the following conditions. (i) d is dually distributive. (ii) the map ϕ : x → d ∧ x is a homomorphism of i (s) onto (d] = {x in i(s) / x ≤ d.} (iii) the binary relation θd on i(s) is defined by x ≡ y (θd) if and only if d ∧ x = d ∧ y, where x, y in i(s) is a congruence relation. 3.17. definition an ideal d of a semilattice s is called standard ideal if ( ) ( ) (x d y x d x y∧ ∨ = ∧ ∨ ∧ ) for all x,y ∈ i(s). the following example shows that every ideal need not be a standard ideal. © cncs, mekelle university issn:2220-184x 26 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 3.18. example let s = {a0, a1, a2,….. an,a, b,c,d,1} be the semilattice as shown in figure 2 and let d = {a0, a1, a2,….. an,a} s. ⊆ then for all x, y ∈ d, x ∨ y = a and a ∈d. next let x ∈ d, t∈s and let t ≤ x. now t ≤ x and x ∈d implies that t = ai , 0 ≤ i ≤ n or t = a. in either case t a ∈ d and d is an ideal of s. similarly we can show that x = {a0, a1, a2,….. an, b}and y = {a0, a1, a2,….. an, c}, are ideals of s. now x y∧ = {a0, a1, ….. an} ; = s, d y∨ x d∧ ={a0, a1,…. an}, ={a(x d y∧ ∨ ) 0, a1,…. an, b}=x and ( ) ( )x d x y∧ ∨ ∧ ={a0, a1,…. an}. therefore ( )x d y∧ ∨ ≠ ( ) ( )x d x y∧ ∨ ∧ , shows that x is not a standard ideal. figure 2. semilattice ideal need not be a standard ideal. 3.19. theorem let l be lattice and let θ be the binary relation on l defined by: x ≡ y(θ) if and only if x ≤ y. if θ is reflexive and symmetric, then θ is a congruence relation if and only if the following three properties are satisfied for all , ,x y z in l. (i) ( ) ( ) ( )x y x y x yθ θ≡ ⇔ ∧ ≡ ∨ (ii) ( ) ( ) ( ), and x y z x y y z x zθ θ θ≤ ≤ ≡ ≡ ⇒ = (iii) ( ) ( ) ( ) and andx y x y x t y tθ θ≡ ≤ ⇒ ∧ = ∧ ( ) ( ) for all t lx t y t θ∨ = ∨ ∈ © cncs, mekelle university issn:2220-184x 27 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 3.19.1. proof: let the binary relation θ defined on a lattice l by: ( )x y θ≡ if and only if x y≤ be reflexive and symmetric. assume that θ is a congruence relation. we prove that θ satisfies the properties (i), (ii) and (iii). (i) let ( )x y θ≡ . then x y≤ and this implies x y x∧ = and x y y∨ = so that ( ) (x y x y )θ∧ ≡ ∨ .conversely, suppose ( ) ( )x y x y θ∧ ≡ ∨ . then x y x y∧ ≤ ∨ and this implies x y x∧ ≤ or ( )x y x θ∧ ≡ . since θ is symmetric we have ( )x x y θ≡ ∧ . since θ is a congruence relation, this gives ( )x y θ≡ . (ii) let x y z≤ ≤ , then x y≤ and y z≤ and this implies ( )x y θ≡ and ( )y z θ≡ . since θ is a congruence relation θ is transitive, so that ( )x z θ≡ (iii) let ( )x y θ≡ and x y≤ , then for t ∈ l, x t y t∨ ≤ ∨ implies ( ) ( )x t y t θ∨ ≡ ∨ and similarly x t y t∧ ≤ ∧ for t in l, we have ( )x t y t θ∧ ≡ ∧ . conversely, suppose θ satisfies the properties (i), (ii) and (iii). we shall show that θ is a congruence relation. given θ is reflexive and symmetric. let ( )x y θ≡ and ( )y z θ≡ . then x y≤ and y z≤ and these imply x y z≤ ≤ . by property (ii) we have ( )x z θ≡ .therefore θ is transitive. let ( )1x x θ≡ and ( )1y y θ≡ so that 1 x x≤ and 1y y≤ . this together with the property (iii) gives 1 1x y x y∨ ≡ ∨ and also ( )1 1x y x y θ∧ ≡ ∧ for 1 1, , , lx y x y ∈ . thus θ satisfies substitution property. hence, θ is a congruence relation. 3.20. theorem let d be an ideal of a semilattice s. then, the following conditions are equivalent. (1) d is standard ideal. © cncs, mekelle university issn:2220-184x 28 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 (2) the binary relation dθ on i(s) defined by ( )dx y θ≡ if and only if ( ) 1x y d x y∧ ∨ = ∨ for some is a congruence relation. 1d d≤ (3) d is distributive and for all x, y ∈ i(s) d x d y, d x =d y∧ = ∧ ∨ ∨ implies x = y 3.20.1. proof: suppose d is an ideal of a semilattice s. define the binary relation dθ on i(s) as ( )dx y θ≡ if and only if ( ) for some 1x y d x y∧ ∨ = ∨ 1d d≤ . (1) => (2) it is sufficient to prove that (i) dθ is reflexive (ii) dθ is symmetric (iii) ( )dx y θ≡ ( ) ( )x y x y θ⇔ ∧ ≡ ∨ (iv) ( ) ( )x y z, x y and y zd dθ θ≤ ≤ ≡ ≡ ⇒ ( )x z dθ≡ (v) x and y≤ ( )x y dθ≡ ⇒ ( )x z y z dθ∧ ≡ ∨ for all x, y, z ∈ i(s) (i) let x, y ∈ i(s) be arbitrary. then, by the definition of dθ we have (x ∨ x) ∨ d1 = x ∨ x for 1x=d d≤ ( )x x dθ⇒ ≡ for all x ∈ i(s). thus dθ is reflexive (ii) for x, y ∈ i(s), x ≡ y(θd) (x ∧ y) ∨ d⇒ 1 = x ∨ y  for some d1 ≤ d. for some d( ) 1y x d = y x⇒ ∧ ∨ ∨ 1 ≤ d ( )y dx θ⇒ ≡ . thus dθ is symmetric. (iii) for some d( ) ( ) 1x y x y d = x ydθ≡ ⇔ ∧ ∨ ∨ 1 ≤ d ( ) ( ) ( ) ( )1x y x y d x y x y⇔ ∧ ∧ ∨ ∨ = ∧ ∨ ∨⎡ ⎤⎣ ⎦ for some d1 ≤ d, and by taking we have x=x y and y= x y∧ ∨ ( x ∧ y ) ∨ d1 = x ∨ y for some d1 ≤ d ⇔ ( )x y= x y dθ∧ ∨ (iv) suppose , x y z≤ ≤ ( ) ( )x y and y zd dθ θ≡ ≡ and ( ) 1x y d x y⇒ ∧ ∨ = ∨ ( ) 2y z d y z∧ ∨ = ∨ for d1, d2 ≤ d. now, 1 2x d = y and y d z∨ ∨ = . © cncs, mekelle university issn:2220-184x 29 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 since, x ≤ y and y ≤ z we have, ( ) ( )1 2 1 2x d d x d d∨ ∨ = ∨ ∨ 2 z∨ = ) = y d for . 1 2d d d∨ ≤ then, = z = x ∨ z ( ) ( ) (1 2 1 2x z d d x d d∧ ∨ ∨ = ∨ ∨ therefore ( )x z dθ≡ . (v) suppose and x y≤ ( )x y dθ≡ ( ) 1x y d = x y⇒ ∧ ∨ ∨ for some d1 ≤ d. since x y≤ ⇒ x z y z∨ ≤ ∨ ( ) ( )( ) ( ) ( )1x z y z d x z y z⇒ ∨ ∧ ∨ ∨ = ∨ ∨ ∨ therefore ( ) . ( ) (x z y z dθ∨ ≡ ∨ ) similarly we can prove that ( ) ( ) ( )x z y z dθ∧ ≡ ∧ . therefore dθ is a congruence relation. to show that (2) (3): ⇒ suppose the binary relation dθ on i(s) defined by ( )x dy θ≡ if and only if for some d( ) 1x y d = x y∧ ∨ ∨ 1 ≤ d is a congruence relation. first we prove that d is a distributive ideal. . for all x,y∈ i(s) we have x ≤ d x ∨ ⇒ x ∧ ( d x) = x [ x ∧ ( d x)] d = x d (*1) ∨ ⇒ ∨ ∨ ∨ ⇒ also x (d ∨ x) = x d (*2) ∨ ∨ ⇒ so from (*1) and (*2) we get [x ∧ ( d x)] d = x (d x) ∨ ∨ ∨ ∨ this together with the definition of dθ implies x ≡ (d x)( ∨ dθ ) (1) ⇒ similarly one can show that ( ) ( )y d y dθ≡ ∨ ⇒ (2) since dθ is a congruence relation, we have x ∧ y ≡ [ ( d x) ∧ (d y)]( ∨ ∨ dθ )  ( ) ( ) ( ) ( ) ( ) ( )x y d x d y d= x y d x d y⇒ ∧ ∧ ∨ ∧ ∨ ∨ ∧ ∨ ∨ ∧ ∨⎡ ⎤⎣ ⎦ ( by the def of dθ ) ( ) ( ) (x y d= d x d y⇒ ∧ ∨ ∨ ∧ ∨ ) since ( ) ( )x y d x d y∧ ≤ ∨ ∧ ∨ . therefore ( ) ( ) ( ) ( )x y d=d x y d x d y∧ ∨ ∨ ∨ = ∨ ∧ ∨ for all x, y ∈ i(s) therefore d is a distributive ideal. next let us assume that d x=d y∧ ∧ and , for all x, y d x=d y∨ ∨ ∈ i(s) we shall show that x = y. © cncs, mekelle university issn:2220-184x 30 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 from (1) we have ( ) ( ) ( )x y d x d y dθ∧ ≡ ∨ ∧ ∨⎡⎣ ⎤⎦ (since dθ is congruence relation) ≡ [d ∨ x)  ∧ (d ∨ x)]( dθ ) (since d ∨ x = d y) ∨ ( ) (d x )dθ= ∨ ( )x dθ≡ (by (1)) but ( )x y x dθ∧ ≡ ( )( ) ( )1x y x d = x y x⇒ ∧ ∧ ∨ ∧ ∨ for some 1d d≤ ( ) 1x y d x⇒ ∧ ∨ = . ( since x ∈ i(s) and i(s) is a lattice) (3) ⇒ also , ( )1 1d x y d x≤ ∧ ∨ = 1d d≤ ⇒ 1d d x=d y≤ ∧ ∧ 1d d y y⇒ ≤ ∧ ≤ 1d y⇒ ≤ and . 1 1 1d x, d y d x y≤ ≤ ⇒ ≤ ∧ so . but by (3),( ) 1x y d x y∧ ∨ = ∧ ( ) 1x y d x∧ ∨ = . therefore and im x=x y∧ plies x ……..(4) y≤ similarly, we can show that y ≤ x ……………(5) therefore from (4) and (5) we have x = y. to show that (3) (1): ⇒ suppose d is distributive and for all x,y∈ i(s) d x=d y, d x=d y∧ ∧ ∨ ∨ implies x = y. we shall show that d is standard ideal or ( ) ( ) (x d y x d x y∧ ∨ = ∧ ∨ ∧ ) for all x,y∈ i(s). for x, y ∈ i(s), let b = and c = (x d y∧ ∨ ) ( ) ( )x d x y∧ ∨ ∧ . we have (x ∧ d) ( x ∧ y ) ≤ x and (x ∧ d) ( x ∧ y ) ≤ d y so that ∨ ∨ ∨ (x ∧ d) ( x ∧ y ) ≤ x ∧ ( d y) or c ≤ b. ∨ ∨ this gives d ∧ c ≤ d ∧ β …….(1) now d ∧ x ≤ d and d ∧ x ≤ (d ∧ x) ∨ ( x ∨ y) = c. ( ) ( ) d x d c d b=d x d y d d y x=d x ⇒ ∧ ≤ ∧ ≤ ∧ ∧ ∧ ∨⎡ ⎤⎣ ⎦ = ∧ ∨ ∧ ∧⎡ ⎤⎣ ⎦ therefore . d b=d c∧ ∧ also since d is distributive ( ) ( ) ( )( )d b=d (x d y ) d x d d y∨ ∨ ∧ ∨ = ∨ ∧ ∨ ∨ ( ) ( )d x d y= ∨ ∧ ∨ © cncs, mekelle university issn:2220-184x 31 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 ( )= d x y∨ ∧ ( )( ) ( )= d d x x y∨ ∧ ∨ ∧ (by absorption property) ( )( ) ( )= d x d x y∨ ∧ ∨ ∧ ( ) ( )=d x d x y d c ∨ ∧ ∨ ∧ = ∨ therefore . d b = d c∨ ∨ hence, and . d b=d c∧ ∧ d b = d c∨ ∨ so by (3) b = c and d is a standard ideal. 3.21. theorem every standard ideal in a semilattice s is a distributive ideal but converse is not true. 3.21.1. proof: by the theorem, 2.20 every standard ideal in a semilattice s is a distributive ideal. in the semilattice s = {a0, a1, a2,….. an,a, b,c,d,1}as shown in figure 3 the ideal d = {a0, a1, a2,….. an,1} is a distributive ideal but not a standard ideal. figure 3. semilattice distributive ideal is not a standard ideal. 3.22. theorem the necessary and sufficient condition for a distributive ideal d to be standard in a semilattice s is that d ∧ x = d ∧ y and d ∨ x = d ∨ y for all x, y ∈ i(s) implies x = y. 3.22.1. proof: immediate from the theorem 2.20. © cncs, mekelle university issn:2220-184x 32 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 3.23 statement suppose ϕ is a homomorphism of a semilattice s on to a semilattice s1 and d is a standard ideal of s. the binary relation θd defined by x ≡ y(θd) if and only if ϕ(x) = ϕ(y) where x, y ∈ s, is such that (i) θd is a congruence relation on s (ii) s/θd is a semilattice (iii) s/θd ≅ s1 3.23.1. proof: (i) first let us show that θd is a congruence relation on s. since ϕ(x) = ϕ(x) for x ∈ s, by definition of θd, we have x ≡ x (θd). thus θd is a reflexive. suppose x ≡ y(θd) for x, y ∈ s.then ϕ(x) = ϕ(y) or ϕ(y) = ϕ(x), which implies that y ≡ x (θd). thus θd is symmetric. suppose x ≡ y(θd) and y ≡ z(θd) for x, y, z ∈ s. then ϕ (x) = ϕ(y) and ϕ(y) = ϕ(z) so that ϕ(x) = ϕ(z) which implies x ≡ z(θd). thus θd is transitive. suppose x ≡ x1 (θ) and y ≡ y1(θ) .then we have ϕ (x) = ϕ(x1) and ϕ(y) = ϕ(y1) now ϕ (x ∨ y) = ϕ(x) ∨ ϕ(y) (as ϕ is homomorphism) = ϕ(x1) ∨ ϕ(y1) = ϕ(x1 ∨ y1) (as ϕ is homomorphism). this implies x ∨ y ≡ (x1 ∨ y1) (θd). similarly, ϕ(x ∧ y) = ϕ(x) ∧ ϕ(y) = ϕ(x1) ∧ ϕ(y1)=ϕ(x1 ∧ y1) implies x ∧ y ≡ x1 ∧ y1(θd). therefore θd satisfies substitution property. hence θd is a congruence relation. (ii) to prove s/θd is a semilattice let s/θd = { [x] θd / x ∈ s}. define ∨ on s/θd by [x] (θd) ∨ [y] (θd) = (x ∨ y) (θd) where [x] (θd), [y] (θd) ∈ s/θd. since x, y ∈ s, x ∨ y ∈ s as s is a semilattice which implies (x ∨ y) (θd) ∈ s/θd. therefore s/θd is a semilattice. (iii) to prove s/θd ≅ s1, let us define a map ψ : s/θd → s1 by ψ ([x] (θd)) = ϕ(x) for [x] (θd) ∈ s/θd. © cncs, mekelle university issn:2220-184x 33 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 for [x] (θd), [y] (θd) ∈ s/θd, [x] (θd) = [y] (θd) ⇒ x ≡ y(θd) ϕ(x) = ϕ(y) ⇒ ⇒ ψ ([x] (θd)) = ψ ([y] (θd)). therefore ψ is well defined. further, for [x] (θd), [y] (θd) ∈ s/θd, ψ ([x] (θd)) = ψ ([y] (θd)) ⇒ ϕ(x) = ϕ(y) ⇒ x ≡ y (θd) [x] (θ⇒ d) = [y] (θd). this show ψ is one-one. let z1∈ s1. then there exists z ∈ s such that ϕ(z) = z1, since ϕ is onto. so [z] (θd) ∈ s/θd and ψ ([z] (θd)) = φ(z) =z1. therefore, for z1∈ s1, there exists [z] (θd) ∈ s/θd ,such that ψ ([z] (θd)) = z1 so that ψ is onto. finally, let us show that ψ is homomorphism. for [x] (θd), [y] (θd) ∈ s/θd we have ψ ([x] (θd)) ∨ [y] (θd)) = ψ ((x ∨ y) (θd)) = ϕ (x ∨ y) = ϕ(x) ∨ ϕ(y) = ψ ([x] (θd)) ∨ ψ ([y] (θd)). therefore ψ is an onto homomorphism.hence s/θd ≅ s1. 3.24. theorem let s be a semilattice, i is an ideal of s and d is a standard ideal of s such that d ⊆ i. then (i) i is a standard ideal in s and if and only if i/d is a standard ideal in s/d (ii) s/i ≅ (s/d) / (i/d) 3.24.1. proof: let s be a semilattice, i is an ideal of s and d a standard ideal of s such that d ⊆ i. (i) let i be a standard ideal in s. to prove that i/d is a standard ideal in s/d, it is sufficient to prove that i/d is the homomorphic image of i. now, define ϕ : s → s/d by ϕ(x) = [x] θd, where x ∈ s. as in theorem 2.23 one can see that ϕ is an onto homomorphism. if we restrict ϕ from i to i/d, we have ϕ(i) is an onto homomorphic image of i and ϕ(i) = i/d, which implies ϕ(i) = i/d is a standard ideal. conversely suppose that i/d is a standard ideal of s/d. © cncs, mekelle university issn:2220-184x 34 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 for x, y ∈ i(s), let y ,x be the homomorphic images of x and y respectively under the map ϕ : s → s/d. since i/d is a standard ideal in s/d, we have yx ≡ (θi/d) (from characterization theorem for standard ideal) ⇒ ( ) yxiy x 1 ∨=∨∧ for some i/dii1 =≤ ⇒ (x ∧ y) ∨ i1 = x ∨ y for some i1 ≤ i. ⇒ x ≡ y(θi) ⇒ i is a standard ideal in s. (ii) to prove that s/i ≅ (s/d)/(i/d) define g: s → (s/d)/(i/d) by g(x) = [ x ] θ(i/d) where x ∈ s. for x = y where x, y ∈ s. ⇒ [ x ] θ(i/d) = [ y ] θ(i/d) ⇒ g(x) = g(y). therefore g is well defined. to show that g is onto, let [ x ] θ(i/d) ∈ (s/d)/(i/d). then x ∈ s/d for some x ∈ s and g(x) = [ x ]θ(i/d) . therefore g is onto. finally, for x, y ∈ s, g(x ∨ y) = [ yx ∨ ] θ(i/d) = [ x ] θ(i/d) ∨ [ y ] θ(i/d) = g(x) ∨ g(y). this shows that g is a homomorphism clearly ker g = i, so that by fundamental theorem of homomorphism s/i ≅ (s/d)/(i/d). 3.25. theorem a semilattice s is distributive ⇔ every ideal d of s is a standard ideal. 3.25.1. proof: assume that in a semilattice s every ideal d is a standard ideal. then by the theorem 2.20, d is a distributive ideal and ( ) ( ) ( )d x y d x d y∨ ∧ = ∨ ∧ ∨ for all x, y ∈ i(s). this is true for all d so that i(s) is a distributive lattice. this implies that s is a distributive semilattce by theorem 2.13 conversely, suppose that a semilattice s is a distributive semillatice and d is an ideal of s. now s is a distributive semilattice of i(s) ⇒ i(s) is a distributive lattice, by theorem 2.13 ⇒ every element in i(s) is standard, since i(s) does not contain n5 or m3 ⇒ every ideal d of s is a standard ideal. 4. conclusion © cncs, mekelle university issn:2220-184x 35 rama ravi kumar,e.s., venkateswara rao, j and srinivas kumar,v (mejs) volume 3 (1):20-36, 2011 in this paper, we investigated the notions of distributive (dually) ideal and standard ideal in a semilattice, and established a characterization theorem of standard ideal. we ascertain that set of all ideals of a semilattice is a lattice. we attain the equivalent conditions for a semilattice (ideal of a semilattice) to be distributive (dually distributive). we confirm that every ideal need not be a standard ideal. we define a congruence relation on a lattice and achieve its equivalent conditions. we get hold of the equivalent conditions for an ideal of a semilattice to be a standard ideal. we set up that every standard ideal in a semilattice is a distributive ideal but converse is not true. we take the necessary and sufficient condition for a distributive ideal to be standard in a semilattice. we concluded with the result that a semilattice is distributive if and only if every ideal of it is a standard ideal. 5. references birkhoff, g. 1967. lattice theory. amer. math. soc., callog publication, xxv providence, r.i. gratzer, g.1962. a characterization of neutral elements in lattices. magyar tub akab. mat. kutato int kozi., 7:191-192. gratzer, g. 1978. general lattice theory. academic press inc. gratzer, g & schmidt, e.t.1961.standard ideals in lattices. acta math. sci. hung., 12: 17-86. hashimoto, j. 1952. ideal theory for lattices. math. japan, 2:149-186. hossain, m.a & noor, a. s. a. 2007. modular and standard filters of a directed above meet semilattice. thammasat. int.j.sc.tech., 12(4):1-5. © cncs, mekelle university issn:2220-184x 36 microsoft word 1. cover pages haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 tillage frequency, soil compaction and n-fertilizer rate effects on yield of teff (eragrostis tef (zucc) trotter) in central zone of tigray, northern ethiopia haftamu gebretsadik1, mitiku haile2 and *charles f. yamoah2 1tigray agricultural research institute, axum agricultural research centre, p.o. box 230, axum, tigray, ethiopia. 2department of larmep, college of dry land agriculture and natural resource management, mekelle university, p.o. box 231, mekelle, ethiopia (*yamoahcf@yahoo.com). abstract in ethiopia, teff is grown for its grain and straw. there is a dearth of information with respect to plowing, compaction and fertilization on vertisols in central zone of tigray. therefore, this study was conducted to determine the effects of plowing frequency, soil compaction and n on teff yields. the experimental design was a split-split plot where main plot was plowing frequency with three levels (once, twice and thrice); sub-plot was compaction with two levels (with and without compaction) and sub-sub plot was n-fertilizer rate with four levels (0kg n/ha, 46kg n/ha, 69kg n/ha and 92kg n/ha). there were three replications. results showed that plowing frequency had no significant effect on most of the yield components except on tillering when the soil is compacted. maximum average number of tillers per plant (2.75) was obtained from compacted plots plowed two times. compaction affected almost all yield and yield components significantly. higher number of tillers per plant (2.64) from non compacted plots and higher stand cover (about 94%) from compacted plots were found. in addition, maximum biomass (4210.617 kg/ha) and grain (1221.98 kg/ha) yields were obtained from compacted plots due to enhanced soil to seed contact resulting in increased plant population. nitrogen fertilizer significantly increased grain yield and yield components. maximum stand cover (94.78%), plant height (92.16cm), panicle length (37.75cm), biomass yield (4724 kg/ha) and grain yield (1387.9 kg/ha) were found from plots receiving 92kgn/ha. partial budget analysis of n fertilizer rates indicted that higher marginal rate of return (525%) were found by applying 69kg n/ha. it is recommended that farmers use 69kg n/ha so as to get economically feasible returns and yield. keywords: compaction, fertilizer n, plowing frequency, teff, vertisol. 1. introduction tef (eragrostic teff (zucc.) trotter) is annual c4 grass that belongs to the family poacea (kebede, et al., 1989). the crop exhibits high variability within regions of cultivation and between plants of the same accession (tadesse, 1993). it is primarily self pollinated and provides naturally inbred lines, though intermittent cross pollination introduces new genetic material to mekelle university issn: 2073-073x 82 mailto:yamoahcf@yahoo.com haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 existing teff population (nicole, 1999). teff is a staple cereal crop in ethiopia. it is grown both for its grain and straw.. in ethiopia, teff performs well in ‘weina dega’ agro-ecological zones or medium altitude (17002400 m above sea level) (nicole, 1999; deckers et al., 1998). according to deckers et al. (1998), the mean temperature and optimum rainfall during the growing season range from 10oc to 27 oc and 450 to 550mm, respectively. the length of growing period (lgp) or the number of days to maturity of teff, considering rainfall and evapo-transpiration of 2-6 mm/day ranges from 60 to 180 days (depending on variety and altitude) with an optimum of 90 to 130 days (deckers et al., 1998). the first plowing for teff production in most part of the country is done as soon as the previous crop is harvested. in less weed prone areas, it is done after the onset of the small (belg) or main (kiremt) rainy seasons (fufa et al., 2001). teff needs high tillage frequencies as compared to other cereal crops in ethiopia. also, it requires firm, level seedbed, free from clods and stumps (deckers et al., 1998). with respect to teff cultivation on vertisols, several plowings are necessary, occasionally as much as 12 times, relative to nitosols (deckers et al., 1998). according to kenea et al. (2001), the tillage frequency for teff in ethiopia ranges from 3 times in nazareth to 12-times in western wellega. though research results indicated teff grain yield increased with increasing number of plowings (iar, 1998). others recommended tillage frequency for teff to be 3-5 times (melesse, 2007), 5-9 times especially in high rainfall areas (tarekegn et al., 1996) and 4-times (nyssen et al., 2000). generally, the tillage frequency is not consistent from region to region, from soil type to soil type and from farmer to farmer. this suggests further research on tillage frequency for teff. due to shrink-swell characteristics of vertisols, teff seeds broadcasted on them during sowing need moderate soil compaction to enhance their attachment with the soil. most teff growing farmers on vertisols trample their teff seedbed either before planting or soon after; in both occasions using cattle, sheep, goats and/or donkeys (tadesse, 1969). according to tari (2007), trampling makes seedbed firm and flat, prevents the soil surface from quick drying, provides a thin coverage of broadcasted seeds, prevents seeds from desiccation and consequently enhances good germination and seedling establishment (tari, 2007; fufa et al., 2001). in addition, the results of comparative studies conducted for three years at debre zeit (dzarc, 1989) on two soil types (inceptisol and vertisol) also revealed that the effect of seedbed trampling by humans mekelle university issn: 2073-073x 83 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 and oxen on grain yield was not significant except at chefe donsa where a significant yield increase was obtained (fufa et al., 2001). melesse (2007) reported the necessity of teff seedbed trampling and recommended the use of subsoilers to break hard pans. according to tari (2007), some farmers in central and north-western zones of tigray trample their teff seedbed using human feet when the land is small and there is less availability of animals. major factors affecting teff fertilizer recommendation are water logging, seasons of planting, cropping history, lodging and weed growth (kenea et al., 2001). the actual rate of fertilizer used by farmers is below the blanket recommendation i.e. 100kg dap/ha and 100kg urea/ha set by the ministry of agriculture and rural development (kenea et al., 2001). generally, the recommended rate of fertilizer for teff is 25 to 40 kg n/ha and 30 to 40kg p2o5/ha on light soils such as nitosols, luvisols and cambisols, and 50-60kg n/ha and 30-35 kg p2o5/ha for heavy soils such as vertisols (deckers et al., 1998). compaction narrows soil pores and reduces water infiltration which result in water logging problem in vertisols. such water logging causes n losses by denitrification. therefore, determining the optimum rate of n under those agronomic practices is necessary. 2. materials and methods 2.1. site description the research was conducted in northern ethiopia, central zone of tigray, wereda la’elay maichew and tabia hatsebo. it is 5 km east of axum town (38034’ and 39025’ east, and 13015’ and 14039’ north). altitude is of 2050 m and classified as sub humid agro-ecology where most of the middle altitude crops such as teff, wheat, fababean are commonly grown. the rainfall ranges from 300 to 800mm/annum. the major arable crop in the area is teff that is mostly widely distributed soil type in the area. 2.2. the experimental design a split-split plot design with three replications was used. the main factor was three plowing frequencies (once, twice and thrice); the sub factor was two compaction levels (with and without compaction) and the sub-sub factor was four rates of nfertilizer (0kgn/ha (control), 46kg n/ha, 69kg n/ha and 92kg n/ha). the teff variety dz-01-974 (dukem) was used and sown at a rate of 30kg/ha. treble super phosphate (tsp) was used as a source of p and applied uniformly to all plots at rate of 60 kg p2o5/ha (a national recommendation of p for teff grown on vertisols). mekelle university issn: 2073-073x 84 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 those plots, which received three plowing frequencies, were plowed first at the beginning of the cropping season; second two months after and the third at sowing. the plots, which received two plowing frequencies, were plowed first, at the beginning of the season and at sowing. the plots, which received one plowing, were plowed only at sowing. sub plots were compacted by trampling with human labor soon after sowing and broadcasting urea and tsp fertilizers. the n fertilizer rates were applied to the sub-sub plots of each compacted and non-compacted plots, half at sowing and the rest at top dressed at time of the crop tillering (i.e. one month after sowing). penetrometer resistance was measured for each sub plots at sowing (0-30 cm) soil depth. penetrometer readings were recorded at 5cm interval along the soil depth. bulk density was determined by the core sample approach. stand percentage, which refers to the percentage of the plot area covered by teff seedlings, was estimated when the teff seedlings reach three to four leaves age. plant height, panicle length and tillering potential were measured by randomly selecting 10 plants per plot. both biomass and grain yields were measured after sun drying for one week. harvest index (hi) was calculated by the formula defined by fleischer et al. (1989): hi = grain yield (kg/ha) x 100 total biomass yield (kg/ha) 2.3. partial budget analysis variable cost of n fertilizer was largely used for partial budget analysis. price fluctuations during the production season were considered. marginal rate of return, which refers to net income obtained by incurring a unit cost of fertilizer, was calculated by dividing the net increase in yield of teff due to the application of each rate to the total cost of n fertilizer applied at each rate. this enables us to identify the optimum rate of n fertilizer for teff production. 3. results and discussion 3.1. penetration resistance and bulk density there is no significant difference in penetration resistance between compacted and noncompacted plots as well as within each soil depth in both plots. the average penetration resistance (mpa) in both compacted and non-compacted plots is 0.83 and 0.77, respectively. maximum penetrometer resistance is observed at soil depth of 10-15cm in compacted and 20mekelle university issn: 2073-073x 85 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 25cm in non-compacted plots. ehlers et al. (1983) indicated that a penetrometer resistance of 3.6 mpa and above under tilled field could impede root growth of oats which is similar to root system of teff. in addition, any penetrometer resistance over 2.0 mpa can significantly reduce root growth and development (ishaq et al., 2001; oussible et al., 1992). therefore, the average penetration penetrometer from the compacted plots of 0.83 mpa is lower than the values mentioned in the literature. this means compaction of the plots does not affect the root penetration of teff. however, there is slight change in bulk density of both plots, 0.79g/cm3 in non-compacted plots against 0.98g/cm3 in compacted plots. table 1. main effects of plowing frequency, compaction and n-fertilizer rates on tillering potential and stand cover. factors tillering potential (tiller/plant) stand percentage plowing frequency p1=once 2.33 90.75 p2=twice 2.67 91.25 p3=thrice 2.38 92.208 se 0.116 1.500 lsd ns ns cv (%) 18.77 3.55 compaction non compacted 2.64a* 88.56b compacted 2.28b 94.25a se 0.094 0.520 lsd 0.259 5.374 cv (%) 18.77 3.55 n-fertilizer rate 0kgn/ha 2.28 83.06c 46kgn/ha 2.50 92.72b 69kgn/ha 2.67 95.06a 92kgn/ha 2.40 94.78ab se 0.134 0.735 lsd ns 3.441 cv (%) 18.77 3.55 *means not connected by the same letters are significantly different at alpha 0.05. mekelle university issn: 2073-073x 86 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 3.2. yield and yield component 3.2.1. stand cover and tillering plowing frequency did not show any significant effect on tillering potential, and stand cover of teff. however, compaction has significant effect on these yield attributes. this may be due to its influence on absorption of nutrients and moisture by the crop. relatively, higher stand cover were found from compacted plots but higher average number of tiller per plant was found from non compacted plots. the higher stand cover from the compacted plots is due to the good attachment of teff seeds with the soil which might have resulted in efficient use of nutrients and moisture as well as improved germination. except in stand cover, the three n-fertilizer rates did not show significant difference from the control in number of tillers per plant. highest stand cover (95%) was obtained from application of 69 kg n/ha. interaction of plowing frequency and compaction significantly affect tillering potential of teff (table.1). relatively higher number of tillers per plant (~3 tillers/plant) was found from plots plowed two times and compacted than the others (table 2). in addition, interaction of compaction with n rates significantly affect tillering because compaction enables teff plants to properly utilize the applied n fertilizer (table 3). table 2. interaction effect of plowing frequency and compaction on tillering potential of teff. plowing frequencies compaction p1 p2 p3 c0 2.67ab* 2.58ab 2.67ab c1 2.00b 2.75a 2.08ab *means not connected by the same letters are significantly different at alpha 0.05. where: p1 = plowing first, p2 = plowing twice, p3 = plowing thrice, c0 = non-compacted plots and c1 = compacted plots, lsd0.05 = 0.575, se = 0.163, cv (%) = 18.8 mekelle university issn: 2073-073x 87 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 table 3. interaction effect of compaction and n-fertilizer rate on tillering potential of teff compaction n-rate (kgn/ha) non compacted compacted 0 2.56ab* 2.00b 46 2.44ab 2.56ab 69 2.22b 3.11a 92 2.44ab 2.33ab *means not connected by the same letters are significantly different at alpha 0.05. where, lsd0.05 = 0.426, se = 0.190, cv (%) = 18.8 interaction effect of compaction and n fertilizer on ground cover was significant. therefore, compaction promotes emergence of teff seedlings through efficient utilization of soil nutrients i.e. the applied n and moisture. relatively, greater ground cover was obtained from compacted plots receiving higher n fertilizer rates (table 4). table 4. interaction effect of compaction and n-fertilizer rate on stand cover of teff. *means not connected by the same letters are significantly different at alpha 0.05. compaction n-rate (kgn/ha) non compacted compacted 0 78.33d 87.78c 46 90.00bc 95.44a* 69 93.33ab 96.78a 92 92.56ab 97.00a 3.2.2. plant height and panicle length only n fertilizer rate caused significant effect in yield attributes. both plowing frequency and compaction had not any significant effect on plant height and panicle length (table 5). teff plants with higher plant height (92cm) and panicle length (38cm) were found by applying high amount n fertilizer (92kgn/ha) (table 5). this is because high nitrogen usually favors vegetative growth of teff which results in taller teff plants heights having relatively greater panicle length. mekelle university issn: 2073-073x 88 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 3.2.3. biomass yield, grain yield and harvest index (hi) there were no significant differences among plowing frequencies in biomass yield, grain yield and harvest index of teff (table 6). though iar (1998) as cited in fufa et al. (2001), reported an increase in grain yield of teff with an increase plowing frequency, such report contradicts our present findings. table 5. main effects of plowing frequency, compaction and n-fertilizer rates on plant height and panicle length. factors plant height (cm) panicle length (cm) plowing frequency 0nce 79.63 34.27 twice 78.75 33.98 thrice 80.77 34.38 se 0.973 0.58 lsd ns ns cv (%) 5.39 7.46 compaction non compacted 79.05 34.85 compacted 80.38 33.68 se 0.793 0.47 lsd ns ns cv (%) 5.39 7.46 n-fertilizer rate 0kgn/ha 57.73d 27.42d 46kgn/ha 81.82c 35.10c 69kgn/ha 87.16b 36.80b 92kgn/ha 92.16a* 37.75a se 1.12 0.67 lsd 1.58 0.95 cv (%) 5.39 7.46 *means not connected by the same letters are significantly different at alpha 0.05. mekelle university issn: 2073-073x 89 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 table 6. main effects of plowing frequency, compaction and n-fertilizer rates on biomass yield, grain yield and harvest index. factors biomass yield (kg/ha) grain yield (kg/ha) harvest index (hi) plowing frequency once 3726.67 1095.09 0.291 twice 3753.80 1098.24 0.289 thrice 4011.48 1206.30 0.300 se 108.64 37.14 0.004 lsd ns ns ns cv (%) 13.23 15.15 6.00 compaction non compacted 3450.679b 1044.4b 0.297 compacted 4210.617a* 1222a 0.289 se 88.70 30.33 0.003 lsd 125.40 42.89 ns cv (%) 13.23 15.15 6.00 n-fertilizer rate 0kgn/ha 2368.27d 665.8d 0.279b 46kgn/ha 3758.77c 1120.6c 0.298a 69kgn/ha 4471.48b 1358.5a 0.304a 92kgn/ha 4724.07a 1387.9a 0.293ab se 125.44 42.89 0.005 lsd 177.40 60.70 0.007 cv (%) 13.23 15.15 6.00 *means not connected by the same letters are significantly different at alpha 0.05. there were significant differences between compacted and non-compacted plots in both biomass (p = 0.0007) and grain yields (p = 0.0035) but not of harvest index (table 6). this agrees with research results from chefe donsa that a significant grain yield of teff was obtained from seedbed compaction (fufa et al., 2001). greater biomass (4211 kg/ha) and grain (1222 kg/ha) yields were obtained from compacted plots than non-compacted plots. the reason for the high yield from compacted plots was due to early emergence and seedling growth as well as high teff ground cover. nitrogen fertilizer significantly (p = 0.0001) improved biomass and grain yield in the control plots and harvest index (p = 0.001) (table 6). the biomass (4,724 kg/ha) and grain (1388 kg/ha) yields were obtained by applying 92 kg n/ha. however, greater harvest index (0.304) was obtained by applying 69kg n/ha which means that more grain yield per unit biomass was obtained from plots receiving this rate. mekelle university issn: 2073-073x 90 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 3.3. partial budget analysis of n-fertilizer rate the partial budget analysis indicates that high marginal rate of return (525%) was obtained by applying 69kg n/ha (table 7). this means that the income obtained by applying 69kg n/ha for teff was more than 5 times a unit total n-fertilizer cost. it is also fair to farmers to use 46kg n/ha for it can bring comparable income which is more than 5 times total n-fertilizer cost. the latter seems to support the nationally recommended n-fertilizer rate for teff. this analysis is done by considering only grain yield of teff. if we add the value of the straw, the return will become more than the already estimated income. table 7. partial budget analysis for n-fertilizer rates. n-fertilizer rates (ni) total cost and total income 0kgn/ha 46kgn/ha 69kgn/ha 92kgn/ha cost 1. labor cost • fertilizer weighing and taking to field 0.00 30.00 30.00 30.00 • fertilizer application 0.00 30.00 30.00 30.00 2. fertilizer cost 0.00 400.00 600.00 800.00 total cost (tc) 0.00 460.00 660.00 860.00 income economic (grain) yield (kg/ha) 666 1121 1359 1388 income (birr/ha) 3330 5605 6795 6940 change in cost (∆c) 0.00 460 660 860 change in income (∆i) 0.00 2275 3465 3610 marginal rate of return (mrr = (∆i)/(∆c)*100) 0.00 494.6% 525% 419.8% where, 1. ∆c = cost of each rate subtracted from cost of the control 2. ∆i = income of each rate (birr/ha) subtracted from the income of control 3. labor costs were calculated by assuming 15birr/labor/day mekelle university issn: 2073-073x 91 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 4. incomes were calculated by assuming 500birr/100kg of teff. 4. conclusion and recommendation plowing frequency did not affect most of the yield and yield attributes of teff. however, it affected tillering of teff when combined with compaction. incidentally, this factor alone did not increase the number of tillers per plant. generally, frequent plowing is not a major factor to increase teff productivity on vertisols, but it is important to control weeds. compaction resulted in low tillering but high ground cover. this means compaction did not favor tillering of teff but it encourages ground cover. interaction between compaction and n also influenced tillering and ground cover of teff. optimum returns were found from biomass and grain yields on compacted plots. the overall outcome of compaction is that it affects teff productivity on vertisols. nitrogen encourages ground cover with the application of 69kg n/ha. high rate of nitrogen (92kg n/ha) resulted in taller plants with relatively longer panicles and greater average biomass and grain yields. the partial budget analysis shows that application of 69kg n/ha can bring an income which is more than five times the cost of n-fertilizer. farmers should not plow their land more than three times as more frequent plowing do not enhance teff productivity on vertisols. plowing three times is appropriate for weed control. compaction contributes to teff productivity by facilitating good seed-soil contact on vertisols hence, farmers should be encouraged to practice it. application of 69kg n/ha gave optimum biomass and grain yields of teff and hence farmers have to use this rate for teff production on vertisols. as an alternative, farmers can also use 46kgn/ha to get comparable income from the crop on vertisols. generally, this implies that farmers can apply n-fertilizers at a rate ranging from 46-69kg n/ha to get optimum teff yield on vertisols. 5. references deckers, j.a., nachtergaele, f.o. & spaargaren, o.c. (eds.). 1998. world reference base for soil resource: introduction. acco leuven/amersfoort. belgium, pp.165. dzarc (debre zeit agricultural research centre). 1989. annual research progress report for 1988/89. debre zeit, ethiopia. mekelle university issn: 2073-073x 92 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 ehlers, w., popke, v., hesse, f. & bohm, w. 1983. penetration resistance and root growth of oats in tilled and untilled loam soil. soil tillage research, 3:261-275. fleischer, j.e., barnes, a.r. & awubila, b. 1989. grain yield and nutritive value of crop residues from three varieties of maize (zea mays l.) crop. in: a. n. said and b.h. dzowela (eds.), overcoming constraints to efficient utilization of agricultural byproducts as animal feed. proceedings of the 4th annual workshop held at the institute of animal research. mankon station, bameda, cameroon, 20-27 october, 1987, africa research network for agricultural by-products (arnab), addis ababa, ethiopia. pp. 239-255. fufa hundera., tesfaye bogale., hailu tefera., kebebew asefa., tiruneh kefyalew., abbera debelo & seifu ketema. 2001. agronomy research in teff. in: hailu tefera, getachew belay & m. sorrels (eds.), narrowing the rift: teff research and development. ethiopian agricultural research organization (earo), addis ababa, ethiopia, pp.167176. iar. 1998. holleta agricultural research center, progress report for the period april 1997 to march 1998. iar, addis ababa, ethiopia. ishaq, m., ibrahim, m., hassan, a., saeed, m. & lal, r. 2001. sub-soil compaction effects on crops in punjab pakistan. ii. root growth and nutrient uptake of wheat and sorghum. soil tillage research, 60:153-161. kebede, h., johnson, r.c. & frris, d.m. 1989. photohsynthetic response of eragrostis tef. to temperature. physiol. plant, 77:262-266. kenea yadeta, getachew ayele & workneh negatu. 2001. farming research on teff: small holders production practices. in: hailu tefera, getachew belay and m. sorrels (eds.), narrowing the rift: teff research and development. ethiopian agricultural research organization (earo), addis ababa, ethiopia, pp.9-23. melesse temesgen. 2007. conservation tillage systems and water productivity implications for small holder farmers in semi-arid ethiopia. phd dissertation, delft university of technology, the netherlands. nicole, d.j. 1999. teff and fingermillet: archaeobotanical studies of two indigenous east african cereals. master thesis. simon fraser university. mekelle university issn: 2073-073x 93 haftamu et al., (mejs) volume 1 (1): 82 – 94, 2009 nyssen, j., poesen, j., mitiku haile, moeyersons, j. & deckers, j. 2000. tillage erosion on slopes with soil conservation structures in the ethiopian highlands. soil and tillage research, 57(3): 115-127. oussible, m., crookstone, p.k. & larson, w.e. 1992. sub-surface compaction reduces the root and shoot growth and grain of wheat. agron. j., 84:34-38. taddesse ebba. 1969. tef (eragrostis tef): the cultivation, usage and some of the known diseases and insect pests. part-2. debre zeit agricultural research station. bulletin no. 60, haile slassie i university, college of agriculture, dire dawa, ethiopia. tadesse, d. 1993. study on genetic variation of landraces of teff (eragrostis tef(zucc.) trotter) in ethiopia. genetic resources and crop ewfutim, 40: 10 1-104. tarekegne, a., gebre, a., tanner, d. g. & mandefro, c. 1996. effect of tillage systems and fertilizer levels on continous wheat production in central ethiopia. in: d. g, tanner., t. s. payne & o. s. abdalla (eds.), the ninth regional wheat workshop for eastern, central and southern africa, addis ababa, ethiopia, cimmyt, pp.56-63. tigray agricultural research institute (tari). 2007. axum agricultural research center. progress report for the period from february 2006 to december 2007. mekelle university issn: 2073-073x 94 momona ethiopian journal of science (mejs), v4(2):29-39, 2012, ©cncs, mekelle university, issn:2220-184x effect of bio-inoculants applied to m5 mulberry under rain-fed condition on growth and cocoon traits performance of silkworm, bombyxmori l. waktole sori 1 * and bhaskar, r. n 2 1 department of sericulture, college of agriculture and veterinary medicine, p. o. box 307, jimma university, jimma, ethiopia ( * waktoletufa@yahoo.com/waktolesg@yahoo.com) 2 college of sericulture, uas (b), chintamani-563 125, india abstract nutrition plays a pivotal role in sericulture. it improves the growth, development, health, feed consumption and conversion of silkworm thereby improving the commercial traits. silkworm, bombyx mori l., is a monophagous insect that drives almost all required nutrients for its growth and development from mulberry leaf. application of the required nutrient in the required amount to mulberry plant is, therefore, very essential for the successful silkworm growth and cocoon production. the present investigation was carried out at the department of sericulture, gkvk, uas, bangalore, india in 2007 with an objective to determine the effect of three bio-inoculants application to m5 mulberry plant on silkworm (pm x csr2) growth, development and coocoon traits. the feeding experiment was laid-out in completely randomized design (crd)with eight treatments replicated three times. the result revealed that the larval growth variables and cocoon traits were significantly better when developing worms were fed on mulberry leaves raised by applying the recommended doses of nutrients. however, the recommended rate of chemical fertilizers application was found either the same or on par with 25 per cent reduced nitrogen and phospherous (np) application when supplemented with bio-inoculants (azotobactersp., aspergillus awamori and trichodermaharzianum). this indicate that 25 per cent reduction of np application does not adversely affect larval growth and cocoon traits when supplemented with the above three microbes. key words: bio-inoculants, cocoon traits, growth variables, m5 mulberry, rain-fed. 1. introduction mulberry, morus alba l., is a sole food plant for silkworm, bombyx mori l. good quality leaf production in mulberry is highly dependent on supply of various inputs especially nitrogen and phosphorus fertilizers (nasreen et al., 1999). singhal et al. (1999) opined that quality of mulberry leaf fed to silkworms is the most important factor that influences successful cocoon production by mulberry silkworm. use of inorganic fertilizers has increased mulberry yield leading to better silkworm productivity (bose and majumder, 1999). but it has been realized that, in the past, this was achieved at the expense of soil health. moreover, some portions of the nutrients applied to the soil are still bound to be unused as they are not available to the plant. this increased the cost of mulberry leaf production. in addition, continuous supplementation of chemical fertilizers to mulberry is hazardous to environment. further, with the application of inorganic fertilizers alone, mailto:waktoletufa@yahoo.com mailto:waktolesg@yahoo.com http://www.scialert.net/fulltext/?doi=ajas.2011.190.195&org=12#687994_ja waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 30 issn:2220-184x particularly in unbalanced manner, problems such as diminishing soil productivity and multiple nutrient deficiencies appears (krishna and bongale, 2001). the deficiency of essential nutrients in the soil has been found to cause nutritional, anatomical and histological disorders in mulberry (shankar, 1990). in effect, complementing inorganic nutrients with bio-inoculants and farm yard manure (fym) is a cost effective means to achieve the desired ends by overcoming the problems of soil degradation and poor leaf production in mulberry sericulture. bio-inoculants are carrier based preparations containing beneficial micro-organisms in a viable form intended for soil or seed application and designed to improve the soil fertility and help the plant growth by increasing their number and biological activity in the rhizosphere (rao, 1998). many nitrogen fixing microorganisms are known to secrete plant growth promoting substances like indole acetic acid (iaa), gibberellic acid (ga) and vitamins besides fixation of atmospheric nitrogen (fallick et al., 1989; el-ruan et al., 1973). usage of n fixers and p solubilizers is known to improve the quality of mulberry leaf besides saving the application of „n‟ and „p‟ chemical fertilizers to certain extent under irrigated mulberry (katiyar et al., 1996). according to goswami (1997) nitrogen fixing bio-inoculants can add 20 to 400 kg n per hectare where as p solubilizing bio-inoculants can solubilize 20-30 kg p2o5 per hectare under optimum conditions depending up on the crop and agro-ecological conditions. further he stated, these crop benefiting bio-inoculants are known to secrete plant growth promoting substances and vitamins needed for improved crop growth and are also known to produce certain antibiotic substances, which help in suppressing the incidence of several root borne pathogens as well as foliar diseases. umesh (1999) reported that conjunctive use of biofertilizers (azotobacter) at the rate of 10 kg/ha with 50 per cent recommended n has a positive effect on cocoon production and silk parameters. venkataramana et al. (2001) studied the integrated effect of triacontanol (a naturally occurring plant growth promoting substance) and azotobacter bio-fertilizer (800 g mixed with 40 kg of fym) on silkworm cocoon yield. accordingly, 7.3 kg more cocoons per 100 disease free laying (dfl) with a profit of rs.10 (0.2 us$) per kg of cocoon was obtained over the control. integrated organic manures packages of practices which included azotobacter, vam, seriphos, vermicompost and green manure application to v-1 mulberry and in turn feeding the leaves to csr2 and csr4 bivoltine silkworm breeds resulted to improved rearing and grainage parameters of silkworms similar to the standard fertilizers application (jagadeesh et al., 2005). waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 31 issn:2220-184x according to sannappa et al. (2005) and raje gowda (1996) application of organic fertilizers to mulberry had a significant influence on cocoon yield, shell ratio, silk productivity and single cocoon filament length. however, information on the effect of bio-inoculants on rain-fed mulberry growth and its subsequent influence on silkworm growth and cocoon production are scanty. thus it was deemed necessary to investigate the effect of bio-inoculants application to rain-fed m5 mulberry variety on growth, development and cocoon traits of mulberry silkworm (pm x csr2),b. mori l. 2. material and methods influence of bio-inoculants (azotobacter sp. @ 20kg/ha/year, aspergillusawamori @ 25 kg/ha/year and trichodermaharzianum @ 20 kg/ha/year), fym @ 12 mt/ha/year and inorganic fertilizers (if) (n, p and k @100:50:50 kg/ha/year and reduced doses plus the above bioinoculants) applied to m5 mulberry on growth, development and cocoon traits of silkworm b. mori (pm x csr2) was studied at gandhi krishi vignana kendra (gkvk), university of agricultural sciences (uas), bangalore (b) in the department of sericulture premises. the bioinoculants were obtained from bio-fertilizers scheme, department of agricultural microbiology, uas (b), gkvk. the treatment details are indicated in table 1. table 1. details of the treatments used for the experiment. notation treatment details t1 standard check: r. npk* + r. fym** t2 75% np through chemical fertilizers + 25% np through aspergillus awamori and azotobacter sp. + r. fym + r. k*** t3 50% np through chemical fertilizers + 50% np through a. awamori and azotobacter sp. + r. fym + r. k t4 75% np through chemical fertilizers + 25% np through a. awamori , azotobacter sp. and trichoderma harzianum + r. fym + r. k t5 50% np through chemical fertilizers + 50% np through a. awamori , azotobacter sp. and t. harzianum + r. fym + r. k t6 r. npk only through fym t7 r. npk only through chemical fertilizers t8 control: no application of any fertilizer key: *r. npk: recommended nitrogen, phosphorus and potash (100:50:50kg/ha/yr). **r. fym: recommended farm yard manure (12 mt/ha/yr). ***r. k: recommended potash (50kg/ha/yr). waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 32 issn:2220-184x mulberry leaves raised by application of the above treatments were fed to silkworm, b. mori, larvae four times a day (6:30 a.m., 11:30 a.m., 3:30 p.m. and 8:30 p.m.) for two rearings (crop i & ii). the larvae were provided with chopped leaf during young stage (i to iii instars) and whole leaf during late-age (iv & v instars) of their growth. bed cleaning was done according to recommended schedule (once during i-instar before first moult; twice during ii-instar after first & before second moults; thrice during iii-instar after second moult, middle of third instar & before 3 rd moult; and every day during iv & v instars) (dandin et al., 2003). as the larvae grew, the required spacing was appropriately provided. in order to control the incidence of diseases, vijetha (recommended bed disinfectant) was dusted at the rate of 5.5 kg/100 disease free layings (dfls) after bed cleaning and 30 minutes before feeding resumes as per the recommendation given by dandin et al. (2003). one dfl was maintained for one treatment per replication; three replications were used for each treatment. observations on silkworm growth variables and cocoon traits were recorded following standard procedures as follows: 2.1. larval weight (g/10) ten larvae were randomly selected from each treatment replication wise at the end of each instar and their weight was recorded using electronic balance. the average larval weight was recorded. besides, on the fifth day of fifth instar, average weight of ten larvae from each treatment replication wise was also computed and recorded. 2.2. larval duration larval duration starting from hatching of the eggs up to 90 per cent of worms attain spinning was recorded as total larval duration. each instars‟ larval duration was also recorded. 2.3. effective rate of rearing (err) (%) err was calculated using the formula: err (%) = (no. cocoons harvested/ number of larvae brushed) x 100 2.4. mean cocoon weight (g/10) after five days of spinning, ten cocoons were harvested from each replication treatment wise and mean cocoon weight was recorded using electronic balance. 2.5. shell weight (g/10) ten cocoons which were used to obtain cocoon weight were cut open and pupae along with the exuviae were removed. then shell weights was recorded and mean shell weight was computed. 2.6. shell ratio waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 33 issn:2220-184x the shell ratio was calculated by using the formula: shell ratio (%) = (weight of cocoon shell/ weight of whole cocoon) x 100 2.7. silk filament length (m) after sorting, the cocoons were stifled by using hot air oven at 90 o c for 20 min. the stifled cocoons were deflossed by hand and used for reeling to record post cocoon parameters. three cocoons from each replication were taken and reeled individually on a single cocoon reeler (epprouvette). the total number of revolution was recorded and converted in to meter by using the formula: l = r x 1.125 where, „l‟ is total length of the filament in meter per cocoon „r‟ is number of revolutions recorded by epprouvette „1.125‟ is circumference of epprouvette the average filament length of three cocoons of each replication was calculated and recorded. 2.8. denier denier was computed using the formula: denier = (silk filament weight (g)/ silk filament length (m)) x 9000 (constant value) 2.9. silk productivity (sp) sp was computed using the formula: sp (cg/day) = shell weight (centigram)/ fifth instar larval duration (days) all data recorded were analyzed statistically for the test of significance using fisher‟s method of “analysis of variance”. the level of significance of “ftest” was at five per cent (cochran and cox, 2000). 3. results the study revealed that application of bio-inoculants, fym and inorganic fertilizers in combination, to the soil and in turn feeding of mulberry leaves produced from such garden to silkworms (pm x csr2), exhibited significantly different results on growth (moulting and larval duration, feeding period, larval weight and effective rate of rearing (err)) and other cocoon traits (cocoon weight, shell weight, shell ratio, filament length, denier and silk productivity) (α = 5%). minimum of 90.19 and 91.34 h (moulting duration), 9.14 and 9.07 days (fifth instar larval duration), 26.52 and 25.61days (total larval duration) and 22.71 and 21.81 days (feeding period) waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 34 issn:2220-184x was recorded from the standard check in the first and second crops, respectively which was found on par with t4 (90.71 and 91.73 h; 9.17 and 9.50 days; 26.55 and 26.19 days; and 22.76 and 22.37 days, respectively) (table 2). table 2. influence of feeding mulberry leaves raised by applying bio-inoculants on rearing parameters of b. mori (pm x csr2). treatments total moulting duration (h) fifth instar larval duration (days) total larval duration (days) feeding period (days) err (%) crop i crop ii crop i crop ii crop i crop ii crop i crop ii crop i crop ii t1 90.19 91.34 9.14 9.07 26.52 25.61 22.71 21.81 92.40 98.00 t2 91.18 92.01 9.20 9.54 26.68 26.26 22.88 22.43 90.29 96.98 t3 92.02 92.93 9.22 9.71 26.77 26.77 22.95 22.90 87.42 96.58 t4 90.71 91.73 9.17 9.50 26.55 26.19 22.76 22.37 91.30 97.71 t5 91.74 92.74 9.21 9.58 26.69 26.32 22.91 22.46 88.09 96.81 t6 93.11 94.18 9.25 9.79 26.84 26.84 22.96 22.91 86.51 96.12 t7 92.84 95.84 9.24 9.83 26.82 27.08 22.95 23.09 86.61 95.95 t8 95.02 96.32 9.26 10.71 28.14 28.27 24.51 24.26 81.08 83.14 f-test * * * * * * * * * * sem± 0.23 0.95 0.024 0.018 0.042 0.134 0.136 0.134 0.462 0.331 lsd @ 5% 0.70 2.89 0.074 0.053 0.129 0.405 0.413 0.407 1.401 1.004 cv (%) 0.44 1.77 0.458 0.311 0.274 0.868 1.022 1.020 0.909 0.602 key: t1standard check (rnpk + rfym), t275% np through if and 25% through a. awamori and azotobacter sp. + rfym + rk t3-50% np through if & 50% np through a. awamori and azotobacter sp. + rfym+rk t4 t2 + trichodermaharzianum, t5 t3 + trichodermaharzianum, t6 rnpk from fym, t7 rnpk only from if, t8 control. table 3. influence of feedingm5 mulberry raised through application of bio-inoculants on larval weight (g/10) of silkworm, b. mori (pm x csr2) treatments instars mature larval weight i ii iii iv v (5 th day) crop i crop ii crop i crop ii crop i crop ii crop i crop ii crop i crop ii crop i crop ii t1 0.0163 0.017 0.209 0.21 0.9700 1.17 5.0733 5.69 21.4000 31.69 22.83 27.87 t2 0.0157 0.016 0.206 0.21 0.9593 1.14 4.7233 5.34 20.2867 29.89 20.70 27.51 t3 0.0147 0.015 0.203 0.20 0.9430 1.10 4.3467 5.00 19.3300 28.68 20.30 26.59 t4 0.0163 0.017 0.208 0.21 0.9653 1.15 4.8033 5.36 20.4700 31.51 21.71 27.83 t5 0.0147 0.015 0.205 0.21 0.9527 1.13 4.5100 5.28 19.4400 29.30 20.54 26.62 t6 0.0143 0.014 0.202 0.19 0.9340 1.06 4.1167 4.88 17.8400 26.87 19.29 25.76 t7 0.0147 0.014 0.202 0.19 0.9347 1.05 4.2400 4.88 18.9800 26.55 19.50 25.69 t8 0.0143 0.014 0.198 0.18 0.8777 1.01 3.9333 4.31 15.8200 23.44 15.58 22.18 f-test * * * * * * * * * * * * sem± 0.0002 0.0007 0.0007 0.008 0.0131 0.039 0.0378 0.247 0.2639 0.545 0.506 0.607 waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 35 issn:2220-184x lsd @5% 0.0007 0.0020 0.0021 0.024 0.0396 0.117 0.1147 0.749 0.8004 1.653 1.536 1.842 cv (%) 2.5494 7.398 0.5837 6.673 2.4029 6.068 1.4656 8.395 2.3809 3.313 4.373 4.006 on the other hand, maximum of 92.40 and 98.00 per cent (err) (table 1), 0.0163 and 0.017 g/10 (i instar larval weight), 0.209 and 0.210 g/10 (ii instar larval weight), 0.970 and 1.170 g/10 (iii instar larval weight), 5.073 and 5.690 g/10 (iv instar larval weight), 21.40 and 31.69 g/10 (v instar 5 th day larval weight), 22.83 and 27.87 g/10 (mature larval weight) were observed in the standard check from the two rearings (crop i & ii), respectively. this treatment was either the same or on par with t4 (table 3). table 4. influence of feedingm5 mulberry cultivated by the application of bio-inoculants on silkworm, b. mori (pm x csr2) cocoon variables. treatments cocoon yield (g/dfl) single cocoon weight (g) single shell weight (g) cocoon shell ratio (%) crop i crop ii crop i crop ii crop i crop ii crop i crop ii t1 640.88 691.11 1.57 1.67 0.30 0.37 19.11 22.72 t2 577.33 626.55 1.52 1.59 0.27 0.35 17.76 22.06 t3 520.89 569.12 1.42 1.51 0.24 0.33 16.90 21.68 t4 638.32 684.91 1.57 1.62 0.30 0.36 19.11 22.43 t5 548.56 570.83 1.46 1.57 0.26 0.34 17.81 21.66 t6 511.16 563.35 1.36 1.48 0.23 0.30 16.91 20.45 t7 514.03 545.21 1.41 1.43 0.24 0.29 17.02 20.28 t8 437.10 469.05 1.29 1.39 0.20 0.25 15.50 17.95 f-test * * * * * * * * sem± 6.97 4.798 0.013 0.0096 0.008 0.0058 0.495 0.331 lsd @ 5% 21.15 14.555 0.038 0.0291 0.025 0.0175 1.502 1.004 cv (%) 2.20 1.409 1.49 1.0852 5.647 3.0762 4.917 2.709 table 5. post cocoon parameters of silkworm, b. mori as influenced by feeding of m5mulberry raised through the application of bio-inoculants. treatments single filament length (m) denier silk productivity (cg/day) crop i crop ii crop i crop ii crop i crop ii t1 870.51 924.03 2.17 2.14 3.28 4.08 t2 839.16 911.13 2.36 2.47 2.93 3.67 t3 783.83 859.05 2.76 2.72 2.60 3.40 t4 868.68 922.53 2.28 2.30 3.27 3.79 t5 807.81 900.61 2.56 2.50 2.82 3.55 t6 752.48 857.25 2.87 2.83 2.49 3.06 t7 780.14 815.23 2.88 3.20 2.60 2.95 t8 711.90 735.55 3.29 3.67 2.16 2.33 f-test * * * * * * waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 36 issn:2220-184x sem± 6.88 12.33 0.06 0.08 0.09 0.06 lsd @ 5% 20.87 37.39 0.174 0.238 0.277 0.175 cv (%) 1.49 2.47 3.780 4.994 5.734 2.982 the direct influence of bio-inoculants application along with organic manures and chemical fertilizers has significant influence on cocoon and post cocoon variables of pm x csr2 silkworm breed both in the first and second crops. maximum cocoon yield (640.88 & 691.11 g/dfl), single cocoon weight (1.57 & 1.67 g), shell weight (0.30 & 0.37 g), cocoon shell ratio (19.11 & %) (table 4), single filament length (870.51 & 924.03 m)and silk productivity (3.28 & 4.08 cg/day)(table 4) were registered in the batch of worms reared on mulberry leaves from standard check, which was statistically non-significantly different from25 per cent reduced np and bioinoculants supplemented treatment (t4). the lowest of all the above growth and cocoon traits were obtained from control batch (table 1, 2, 3 & 4). on the other hand, minimum filament denier of 2.17 and 2.14 was registered in the batch of worms reared by feeding of mulberry leaves raised by the application of rnpk and rfym (t1), which was on par with t4 (2.28 and 2.30). maximum filament denier of 3.29 and 3.67 was recorded from the control (table 5). 4. discussion the present study revealed that application of bio-inoculants, fym and if in combination, to the soil of mulberry garden and in turn feeding of mulberry produced from such garden to silkworm, b. mori (pm x csr2 breed) exhibited significant results on growth (moulting duration, larval duration, feeding period, larval weight and err), cocoon (cocoon yield & weight, shell weight, &cocoon shell ratio) and post cocoon (single filament length, filament denier & silk productivity) variables. however, minimum moulting duration, fifth instar larval duration, total larval duration, feeding period, and denier was recorded from the standard check in the first and second crops, respectively which was found on par with 25 per cent reduced np application supplemented with bio-inoculants. on the other hand, maximum err, larval weights, cocoon yield, single cocoon weight, cocoon shell ratio, single filament length and silk productivity were registered from the standard check fed batches of silkworms both in crop i and ii, respectively. this treatment was either the same or on par with t4 (bio-inoculants at 20 kg/ha of azotobacter + 25 kg/ha of a. awamori + 20 kg/ha of t. harzianum + 75 per cent recommended np each through chemical fertilizer with full recommended dose of fym and k). these results are in close conformity with the findings of umesh (1999) who opined the conjunctive use of waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 37 issn:2220-184x azotobacter and half the recommended dose of n had positive influence on cocoon and silk productivity in mulberry silkworm under irrigated condition. an increase of 7.3 kg/100dfl in cocoon yield was reported by venkataramana et al. (2001) when triacontanol and azotobacter were integrated in mulberry cultivation. further, integrated organic manures packages of practices which included azotobacter, vam, seriphos, vermicompost and green manure in v-1 mulberry cultivation didn‟t negatively affected the rearing and grainage parameters of csr2 and csr4 bivoltine silkworm breeds (jagadeesh et al., 2005). according to sannappa et al. (2005) application of fym @ 20 mt/ha/yr + azotobacter @ 20kg/ha/yr + npk @ 300: 120: 120kg/ha/yr to mulberry resulted in higher cocoon yield (291.6g/200 larvae), shell ratio (19.96%), silk productivity (3.503 cg/day) and cocoon filament length (666.0 m). raje gowda (1996) reported that, mean cocoon and shell weight, shell percentage and filament length as well as other economic parameters of silkworm, b. mori are significantly better when inorganic fertilizers are integrated with bio-fertilizers (a. awamori and aspergillus sp.) than inorganic fertilizers alone. favorably the beneficial effect of bio-inoculants can be envisaged from the present findings, under rain-fed condition, which clearly demonstrate the realization of silkworm growth, development and cocoon improvement on par with the standard check. thus supplementation of bio-inoculants along with fym and if to mulberry can result to the required ultimate cocoon productivity without significant sacrifices. therefore, np can be reduced to the tune of 25 per cent without affecting the silkworm, b. mori, growth, development and cocoon productivity. this may be due to the fact that, the inoculation of bio-inoculants had resulted in availing the macro-and micronutrients to mulberry root thereby maintaining the quality of mulberry leaves which provided all the required nutrients to the larvae, hence better growth and cocoon productivity. 5. conclusion silkworm, b. mori, larval growth and cocoon traits, both quantitatively and qualitatively, are not significantly affected when chemical fertilizers (nitrogen and phospherous (np)) application to mulberry plant is reduced by 25 per cent when the same is supplemented with bio-inoculants (azotobactersp., aspergillusawamori and trichodermaharzianum at 20, 25 and 20 kg/ha/year, respectively). thus in view of the current increase in price of chemical fertilizers and waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 38 issn:2220-184x environmental concerns on the negative impact of such chemical fertilizers, sericulturist can use these microbials to maintain the productivity of mulberry garden thereby silk cocoon. 6. acknowledgement the authors acknowledge the financial assistance of ministry of education, ethiopian government and uas, bangalore for hosting the study. 7. reference bose, p.c & majumder, s.k. 1999. nitrogen fertilizer recommendation of mulberry (morus alba l.) based on the mitscherlich-bray concept. sericologia, 35(2): 331-336. cochran & cox. 2000. experimental design procedures for the behavioral sciences. cole publishing company, 319-380pp. dandin, s. b., jayaswal, j & giridhar, k. 2003. handbook of sericulture technologies, csb, bangalore, 259p. el-ruan, s.m., khodain, a.f.a & el-moscing, m.m. 1973. effect of gibberlic acid, indole acetic acid, some vitamins and some amino acids in nitrogen fixation of azotobacter chroococum. proceedings of egyptian academy of sciences, 24: 63-67. fallick, e., okon, y., epstein, e., goldman, a & fischer, m. 1989. identification and quantification of iaa and iba of azospirillum brasilense inoculated with maize roots. soil biol. biochemistry, 21: 147-153. goswami, n.n.1997. concept of balanced fertilization, its relevance and practical limitations. fertilizer news, 42:15-19. jagadeesh, n., philomena, k. l., magadum, s.b & kamble, c.k. 2005. studies on generation of bivoltine seed cocoons by integrated eco-friendly technology package. progress of research in organic sericulture and seri-byproduct utilization, 142-147. katiyar, r.s., das, p.k., bhogesha, k & choudhury, p.c. 1996. effect of dual inoculation (bacterial biofertilizers and va mycorrhiza) on growth and yield of mulberry under irrigated condition. annual report, csr & ti, mysore, 29p. krishna, m& bongale, u.d. 2001.role of organic manures on growth and quality of mulberry leaf and cocoons. indian silk, 40 (2): 11-12. nasreen, a., cheema, g.m & ashfaq, m.1999. rearing of silkworm bombyx mori l. on alternative food parts. pakistan journal of biological sciences, 2: 843-845. waktole, s and bhaskar, r. n (mejs) volume 4(2):29-39, 2012 © cncs, mekelle university 39 issn:2220-184x raje gowda. 1996. response of mulberry to sources of p as influenced by „p‟ solubilizing micro-organisms in relation to cocoon production. m.sc. (seri.) thesis, univ. agril. sci., bangalore, 198p. sannappa, b., doreswamy, c., ramakrishna n., govindan, r & jagadish, k.s. 2005. influence of sources of organic manures applied to s-36 mulberry on rearing performance of silkworm (pm x csr-2). progress of research in organic sericulture and seribyproduct utilization, 131-136pp. shankar, m.a. 1990. nutritional management of mulberry and its effect on silkworm growth, development and silk quality. phd. thesis, uas, bangalore, 410p. singhal, b.k., malav, r., sarkar, a & datta, r.k. 1999. nutritional disorders of mulberry (morus spp.): iii. leaf nutrient guide for secondary nutrients. sericologia, 39 (40): 599609. rao, s. n. s. 1998. bio-fertilizers in agriculture. oxford and ibh publishing co., new delhi, 155p. umesh, m.d. 1999. response of rfs135 and m5 varieties to azatobacter inoculation in relation to growth, yield of mulberry and cocoon production under dry-land alfisols. m.sc. (agil. mic.) thesis, uas, bangalore, 98p. venkataramana, p., sanathkumar, y. n., das, p. k & datta, r. k. 2001. studies on the integrated effect of triacontanol and azotobacter bio-fertilizer on mulberry leaf and silkworm cocoon yield. indian journal of sericulture, 40 (1): 71-75. implication of using mathematics tools to the understanding of teachers in teaching mathematics research article http://dx.doi.org/10.4314/mejs.v15i1.6 momona ethiopian journal of science (mejs), v15(1): 78-88, 2023 ©cncs, mekelle university, issn:2220-184x submitted on: 6 th december 2019 revised and accepted on: 5 th february 2023 implication of mathematical tools to teachers’ method of teaching high school mathematics: the case of mekelle zone, tigray, ethiopia tsegay tesfay*, abreha tesfay and tsge bayrau department of mathematics, college of natural and computational sciences, p. o. box 231, mekelle university, mekelle, ethiopia (*tsegay.tesfay2@mu.edu.et, abrehatwmu@gmail.com, tbtsge2002@gmail.com). abstract education with science and mathematics as its major components determines the level of welfare of people and a nation. nowadays, great attention is given to technological advancements and mathematics education. hence, this paper explicitly discusses the use of mathematics laboratories and their implication for teaching mathematics, finding out the practices and impact on teaching mathematics and teachers’ frequency of using teaching aids (manipulatives) in high schools of mekelle zone. manipulatives are valuable aid to teachers that can be used by analyzing students’ concrete representations of mathematical concepts. in addition to this, topics like geometry and measurement are topics that are frequently taught using tools. on the contrary, solving equations, relations, and functions is rarely taught using these manipulatives. this study indicates that there is no direct correlation between teachers’ teaching experience years and the use of manipulatives in their classrooms. it is, therefore, recommended that mathematics teachers should get training and workshops on the use of teaching aids (manipulatives), useful software like (geogebra, sketchpad, and other timely used technologies) and other methods of teaching mathematics in mathematics laboratories. keywords: tools, mathematics laboratory, manipulative, models, mekelle, ethiopia. 1. introduction developing countries like ethiopia have been facing problems in designing and implementation relevant educational policy to disseminate quality education and training. the issues are mainly indications of the teaching-learning processes. education with science and mathematics as its major components determines the level of prosperity and welfare of people and a nation at large. in the case of ethiopia, the promotion of science, mathematics, engineering, and technology education (science and technology) is visible at all levels of the education system (general education, tvet and higher education). within general education system in ethiopia (grades 112), science and mathematics education is essential for cultivating a generation of scientists and for poverty reduction of the population. greater understanding of the relevance of science and mathematics education for development is the foundation of any effort to improve science and mathematics. mailto:tsegay.tesfay2@mu.edu.et mailto:tsegay.tesfay2@mu.edu.et tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 79 issn: 2220-184x however, there is a general dissatisfaction in the quality of education. the results are in general unsatisfactory. students fail to grasp the spirit of the subject and often unable to apply their knowledge to advanced work or to practical problems. generally, students are afraid of studying mathematics (bezabih, 2008). and the society and most students view mathematics as a collection of rigid rules and mysterious procedures that seem to be unrelated to each other and require total mastery with little or no understanding. a lot of research studies worldwide had been done on the methods of teaching mathematics comparing one another and emphasizing the student-centered approach for better performance. yet, the problem is still recurring, to offer quality training and education and achieve its national educational goal. ethiopia has been continually revising its curriculum to suit it to the needs of society. these include, among other things, content organization, methodologies of teaching, teacher preparation (capacity building) and implementation strategies. the implementation of active learning method is imperative to develop the problemsolving skills and increasing competencies of the students when learning at various levels. yet, here we again need to know how to implement that active learning which is one of the strategies of teaching. the secondary schools are the stepping stones to colleges and university education. however, the results in mathematics and physics are low as compared to the other subjects here in mekelle, ethiopia. hence, it is believed that students understand abstract mathematical ideas better when they solve problems through manipulatives. hence, the team tried to investigate the use of mathematics laboratory and modern manipulative in teaching mathematics and teachers’ practices in using teaching aids (algebra tails, dies, geoboards, etc) in high schools. the results of this study obtained from 45 high school mathematics teachers in mekelle, therefore, will provide information about the problems that high school teachers face in making use of teaching aids and software packages which can help to teach mathematics in high schools. the result may also be input to support the educational process of mekelle zone by providing solutions for the current problems experienced by students, teachers, school authorities, and government bodies at different levels. before the rapid development of technology, the teaching process was reduced to the teachers’ verbal presentation of material and using chalk to write on the blackboard. although speech remains the most important asset in the teacher’s work, today’s teaching process is difficult to imagine without the use of different modern teaching and learning resources tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 80 issn: 2220-184x (bušljeta, 2013). the contribution of these resources to the teaching and learning process is diverse. since students are surrounded by visual representations and audiovisual and auditory materials daily, owing to media such as television and the internet, it is difficult to imagine today’s educational process without the use of various teaching and learning resources. but, in countries like ethiopia, most public and private schools do not use technology in teaching mathematics. in this light, a study was conducted to assess the availability of mathematical tools in schools, analyze the extent of using mathematical tools by high school teachers, analyze the implication of using mathematical tools (manipulatives) to teachers’, understanding in their instructional process, and recommend possible intervention mechanisms. 2. literature review for the last two decades, many trials and amendments have been made at all educational levels to suit the goals of education to the needs of the society (oecd, 2010). since high school education is the basis, governments made special emphasis on the re-alignment of school curriculum with universities. the study of mathematics has long been recognized worldwide as important in the understanding of other subjects like chemistry, biology, and physics. (education, education sector development program, 2010) the subject mathematics and its teaching and learning processes are essential components of mathematics education in almost all schools and at all levels. with this major idea in mind, these components should, therefore, be supported by research results in the area. thus, the documents we have tried to review focuses on research related to the attitude of teachers towards mathematics (including numbers and their operations), learning environment in the classroom, and the use and effectiveness of technology (including hands on materials and software packages) in mathematics classrooms. for example, by 1990, basic cognitive research on the important roles of representations in learning abstract mathematics and science concepts had largely concluded that the application of technology must be domain specific to be effective (kaput, 1992). thus, summaries of different research works and positions of researchers on these issues are considered in this review. 2.1. role and impact of using manipulatives one way to help slow learner pupils’ understand mathematical concepts or ideas are to use the laboratory approach (loh, 2002). in this approach, the learner can have hands-on experience tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 81 issn: 2220-184x through the manipulation of concrete materials from which he/she can see how some ideas or concepts have come about. all types of students need to develop the ability to select appropriate manipulatives, electronic tools and computational tasks to investigate mathematical ideas and to solve problems. using manipulative to construct representations help students to • see arrangements and relationships, • make connections between the tangible and the abstract, • test, revise and confirm their reasoning and this helps students check the solution, and • remember how they have solved a problem and communicate their reasoning to others. as a result, this helps to encourage active participation in the classroom. manipulatives are necessary tools for supporting the effective learning of mathematics by all students. these concrete learning tools invite students to explore and represent abstract mathematical concepts in varied, concrete, tangible and visually rich ways. in addition, technology makes possible for students to see connections between multiple representations of a concept and to gain insights into abstract entities such as functions (merrilyn goos, 2007). in parallel, doing mathematical concepts using manipulatives make classrooms active and it encourages teamwork with an active participation of all the members of the group. different studies concluded that mathematics achievement is increased through the longterm use of concrete instructional materials and that students’ attitudes towards mathematics are improved when they have instruction using concrete materials provided by teachers knowledgeable about their use. manipulative materials can (1) help students understand mathematical concepts and processes, (2) increase students’ flexibility of thinking, (3) be used creatively as tools to solve new mathematical problems, and (4) reduce students’ anxiety while doing mathematics. manipulatives are also valuable aids to teachers. by analyzing students’ concrete representations of mathematical concepts and listening to their reasoning, teachers can gain useful insights into students thinking and providing support to help enhance their thinking. mathematics teachers have intended to use mathematical tools which support mathematical activities. such materials as algebra models, kites, dies, geoboards and other locally made teaching aids are essential for advancing the teaching methods. tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 82 issn: 2220-184x 2.2. mathematics laboratory mathematics laboratory is a specific place with relevant and up-to-date equipment known as instructional materials manipulatives, designated for the teaching and learning of mathematics and other scientific or research works. mathematics laboratory can contribute to the learning of the subject in the following sense: 1. it provides an opportunity to students to understand and internalize the basic mathematical concepts through concrete objects and situations. 2. it enables students to verify or discover several geometrical properties and facts using models or paper cutting and folding techniques. 3. it helps students to build interest and confidence in learning the subject. 4. the laboratory provides an opportunity to exhibit the relatedness of mathematical concepts with everyday life. 5. it provides greater scope for individual participation in the process of learning and becoming autonomous learners. 6. it provides scope for greater involvement of both the mind and the hand which facilitates cognition. 7. the laboratory allows and encourages the students to think, discuss with each other and the teacher and assimilate the concepts in a more effective manner. 8. it enables the teacher to demonstrate, explain and reinforce abstract mathematical ideas by using concrete objects, models, charts, graphs, pictures, posters, etc. 3. data analysis and discussion 3.1. data collection method data was collected from 7 high schools and preparatory schools of mekelle zone. among all teachers working in these high schools, 45 teachers including department heads were selected randomly and purposefully for the department heads. the study team has employed mixed research approach (quantitative and qualitative) which included both closed and open-ended questions. table 1 highlights the social and demographic characteristics of the 45 respondents from mekelle city from seven high school and preparatory school teachers. tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 83 issn: 2220-184x table 1. demographic characteristics. s. no. observation points values frequency percent 1 sex male 30 66.7% female 15 33.3% 2 age 20-30 4 8.9% 30-40 26 57.8% 40-50 13 28.9% above 50 2 4.4% 3 educational level diploma 0 0.0% bsc/ bed 40 88.9% msc/ med 5 11.1% phd 0 0.0% 4 experience below 3 years 0 0.0% 3-6 years 1 2.2% 6-9 years 1 2.2% 9-12 years 9 20.0% above 12 years 34 75.6% table 1 indicates that about 75.6 % of the teachers have 12 and above years of teaching experience and 89% of them are bsc/ bed holders. the data show majority of the teachers are with required qualification to teach high school mathematics (grade 9 & 10). 3.2. discussion and results table 2 shows that nearly 87% of the teachers responded that teaching using mathematical tools is very interesting. the number of respondents who said students feel that mathematics is an easy subject when it is taught by tools is 36 teachers out of 45. table 2. feelings and rate. s. no. questions observations frequency percent 1. how do you rate teaching mathematics using teaching aid? interesting 39 86.7% moderate 5 11.1% boring 1 2.2% 2. what do students feel when they are taught mathematics by the help of teaching aid in? easy 36 80.0% moderate 8 17.8% hard 1 2.2% table 3 indicates the responses on whether there is a separate room for mathematics laboratory in their school or not. accordingly, 97.8 % said that there is no separate lab room for mathematics. even if standards of the ministry of education show that a school should have a separate room for mathematics laboratory, almost all schools don’t have a laboratory. tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 84 issn: 2220-184x table 3. existence of laboratory. s. no. questions observations frequency percent 1 is there any separate classroom for mathematics laboratory in your school? yes 1 2.2% no 44 97.8% table 4 indicates that 75 % of the respondents did not take any additional training or workshop on the use of manipulatives like algebra models and other mathematics tools which help them teach mathematics with teaching aids. table 4. attending for a workshop. s. no. questions observations frequency percent 1 have you ever attended any training/ workshop on algebra models using teaching aids? yes 11 25 % no 33 75 % table 5 and figure 1 indicate that a relatively large number of teacher respondents replied that they use mathematical tools for topics such as measurement and geometry as well as probability. it can be observed from table 5 that topics such as number theory and solving equations are taught without using tools. table 5. topics in relation to the frequency of using mathematical tools. s. no. observation rate frequency percent 1 number system and number theory never at all 19 43.2% rarely (once in a topic) 12 27.3% sometimes (two or three times per week) 12 27.3% all through the topics 1 2.3% 2 solving equations and computations never at all 25 56.8% rarely (once in a topic) 8 18.2% sometimes (two or three times per week) 10 22.7% all through the topics 1 2.3% 3 measurement and geometry never at all 1 2.2% rarely (once in a topic) 8 17.8% sometimes (two or three times per week) 21 46.7% all through the topics 15 33.3% 4 relations and functions never at all 9 20.5% rarely (once in a topic) 12 27.3% sometimes (two or three times per week) 20 45.5% all through the topics 3 6.8% tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 85 issn: 2220-184x 5 coordinate geometry never at all 6 13.6% rarely (once in a topic) 16 36.4% sometimes (two or three times per week) 17 38.6% all through the topics 5 11.4% 6 data collection and analysis never at all 11 24.4% rarely (once in a topic) 13 28.9% sometimes (two or three times per week) 19 42.2% all through the topics 2 4.4% 7 probability never at all 3 6.7% rarely (once in a topic) 11 24.4% sometimes (two or three times per week) 21 46.7% all through the topics 10 22.2% figure 1. bar charts for different components. table 6. rating of topics with frequent use of teaching aids. s. no. questions observations frequency percent 1. from all the topics in table 5, rate three topics in which you use teaching aids frequently? number system and number theory 3 6.8% solving equations and computations 1 2.3% measurement and geometry 22 50.0% relations and functions 7 15.9% coordinate geometry 3 6.8% data collection and analysis 0 0.0% probability 8 18.2% tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 86 issn: 2220-184x from results of table 6, only 22 (50%) respondents said that they use teaching aids frequently when they teach topics such as measurement and geometry as well as probability (18.2%). from these sample data, it can be observed that math teachers are not using teaching aids when teaching different topics/ chapters. from table 7, 36 (80%), 28 (62.2%) and 41 (93.2%), respectively, have replied they did not take any software training, no internet service in their school and they did not apply any software for teaching mathematics. table 7. response on technology related questions. s. no. questions observations frequency percent 1 is there an ict lab in your school? yes 28 62.2% no 17 37.8% 2 have you ever taken any software training that helps you teach mathematics? yes 9 20.0% no 36 80.0% 3 do you have an internet service in your school? yes 17 37.8% no 28 62.2% 4 have you ever used any software to teach mathematics? yes 2 4.5% no 41 93.2% 3 1 2.3% table 8. response on training related questions. s. no. questions observations frequency percent 1. deepening mathematics knowledge no need 1 2.3% less important 7 15.9% moderately needed 10 22.7% highly needed 26 59.1% 2. understanding students participation in mathematics no need 6 13.3% less important 11 24.4% moderately needed 14 31.1% highly needed 14 31.1% 3. training on how to use technology in mathematics instruction no need 2 4.4% less important 8 17.8% moderately needed 12 26.7% highly needed 23 51.1% 4. training on how to assess students learning in mathematics no need 3 6.8% less important 7 15.9% moderately needed 15 34.1% highly needed 19 43.2% 5. training on how to teach mathematics in a class that includes students with special needs no need 2 4.4% less important 5 11.1% moderately needed 18 40.0% highly needed 20 44.4% tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 87 issn: 2220-184x table 8 presents trainings are necessary in different areas. therefore, according to the respondents, on deepening mathematical knowledge (contents) is highly needed (59.1%), the use of technology (51.1%), assessment of student learning (43.2%) and treatment of students with special needs (44.4%) is highly needed for math teacher. 4. conclusion and recommendations 4.1. conclusions from the discussions made on this study, one can observe that most high school teachers of mekelle zone are not using manipulatives to the required level. it can be observed that some mathematics teachers also perceive that there is no need a laboratory for teaching mathematics. and all schools in mekelle do not have a separate room for mathematics laboratory. those teachers who use mathematics tools (manipulatives) are still using for some specific topics like geometry and measurement (shapes of figures, angles, etc). the aids mostly used are locally made and they are not accurately measured. on the other hand, most teachers never use teaching aids (manipulatives) for topics like number system and number theory, solving equations and computations and rarely use these tools for relations and functions, data collection and analysis. in this study, it is possible to conclude that there is no direct correlation with the use of tools and number of years of teaching experience. 4.2. recommendations based on the results of this study, governmental, and non-governmental organizations should share their part to equip high schools with internet access and other technologies. so, teachers should be acquainted with new teaching aids. based on the results of this study, the following recommendations are made. 1. mathematics laboratory should be established in each school. and it should be equipped with different materials such as algebra models, geoboard, and other softwares like (geogebra, sketch pad) and many other locally made objects. 2. high school and preparatory school teachers should be given on job training for the use of new technology in teaching mathematics. this may be done depending on selected topics/chapters and grade levels they teach. tsegay tesfay, abreha tesfay and tsge bayrau (mejs) volume 15(1):78-88, 2023 © cncs, mekelle university 88 issn: 2220-184x 3. curriculum planers in teacher education should modify courses which are related to teaching mathematics. higher institutions should support these high schools and preparatory schools by developing new tools for teaching mathematics. 4. since teaching with tools is good, teaching aids in the educational system should be formal, institutionalized for making, distributing and training for teachers. 5. school administrators of the local region should establish an office for facilitating, distributing mathematical tools. 5. acknowledgements we would like to thank mekelle university for the financial support. secondly we thank staffs of mathematics department for support and informal guidance. finally, our special thanks go to regional bureau of education for sending the high school teachers. and at last, we duly acknowledge the anonymous reviewers for their critical comments that helped in improving the quality of the paper. 6. conflict of interests no conflict of interests 7. reference bezabih, m. 2008. best methods and techniques of teaching mathematics. adisababa: mega. bušljeta, r. 2013. effective use of teaching and learning resources. historical and pedagogical journal, 55–69. education, m. o. 2010. education sector development program. adisababa: federal ministry of education. kaput, j. 1992. technology and mathematics education. new york: macmillan. loh, c. y. 2002. the laboratory approach to teaching mathematics: some examples. singapore: institute of education. merrilyn goos, g. s. 2007. teaching secondary school mathematics. australia: allen & unwin. oecd. 2010. mathematics teaching and learning strategies. corrigenda: oecd microsoft word 1. cover pages daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 multidimensional and multi-parameter fortran-based curve fitting tools daniel tsegay and *alem mebrahtu department of physics, college of natural and computational sciences, mekelle university, p.o. box. 3044, mekelle, ethiopia (*alem.mebrahtu@mu.edu.et) abstract the levenberg-marquardt algorithm has become a popular method in nonlinear curve fitting works. in this paper, following the steps of levenberg-marquardt algorithm, we extend the framework of the algorithm to two and three dimensional real and complex functions. this work briefly describes the mathematics behind the algorithm, and also elaborates how to implement it using fortran 95 programming language. the advantage of this algorithm, when it is extended to surfaces and complex functions, is that it makes researchers to have a better trust during fitting. it also improves the generalization and predictive performance of 2d and 3d real and complex functions. keywords: levenberg-marquardt algorithm, nonlinear curve fitting and least square fitting technique. 1. introduction levenberg-marquardt (lm) algorithm is an iterative technique (levenberg, 1944; kelley, 1999; avriel, 2003; marquardt, 1963; bates & watts, 1988; box, et al., 1969; and gill, et al., 1981) which helps in locating the discrepancy between a given model and the corresponding data. such functions are usually expressible as sum of squares of nonlinear functions. the lm algorithm has become a standard technique for nonlinear least-square problems (lourakis, 2005; lampton, 1997; arumugam, 2003; coope, 1993; and madsen, et al., 2004) and can be thought of as a combination of steepest descent and the gauss-newton methods. the paper is presented as follows: in section one, we present a brief introduction about the lm algorithm. in section two we discuss about the least square fitting technique. section three elaborates vanilla gradient descent method. in the fourth section we present newton’s method. a more detailed discussion of lg algorithm is presented in section five. section six discusses about the implementation of the lm algorithm. in the last section we present a brief summary of the paper. mekelle university issn: 2073-073x 95 mailto:alem.mebrahtu@mu.edu.et http://en.wikipedia.org/wiki/donald_marquardt daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 1.1. least-square’ fitting technique suppose we have a set of experimental data points n ix{ , ,iy ,l ,if iσ } , where ,…, n for which we need to make a fitting. here 1=i ix ( ),..., ii yx≡ are the data coordinates, is the data value and if iσ �is the data error bar. next we take a model which can estimate the values of as a function of and a set of internal variable parameters : . f ix ( ,..., ii yx≡ ) ( )mpppp ,...,, 21≡ ( )pxf , let us construct the chi-square function: ∑∑ == =⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − ≡ n i i n i i ii pr pxff p 1 2 2 1 2 )( ),( )( σ χ (1) where ( ) i cii ci pxff pr σ , )( − = is called residue function. the goal of the least square method is to determine the parameters of the regression function p ( )pxf , so as to minimize the squared deviations between and if ( )pxf i , for all data points: ni l1= . if we assume that all measured values of are normally distributed with standard deviations given by if ,iσ then ‘statistically-the-best’ match would correspond to the minimal value of . thus, the suitable model is essentially the one which gives the minimum value of the chi-square with respect to the parameters. that is why the method itself is called the ‘least-square’ technique. of course, the error bars are determined not only by a statistical noise, but also by systematic inaccuracies, which are very difficult to estimate and are not normally distributed. however, to move on, we assume that they are some how accounted for by the values 2χ iσ . other approaches that are useful in determining the best-fit parameters for non-linear functions by minimizing iteratively include newton’s method and gradient descent method. ( pxf , ) 2χ 1.2. vanilla gradient descent method the gradient descent method is simply an instinctive moving in the ‘steepest descent’ direction, which is apparently determined by the minus-gradient: ∑ = ∂ ∂ = ∂ ∂ −≡ n i k ci ci k c k p pr pr p p 1 2 )( )( )( 2 1 χ β ( ) ( ci k n i cii px p fpxff , , 1 2 1 , ∂ ∂ )−= ∑ = σ mekelle university issn: 2073-073x 96 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 or = ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mβ β β m 2 1 ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ m cm m c m c cmcc cmcc p pr p pr p pr p pr p pr p pr p pr p pr p pr )()()( )()()( )()()( 21 22 2 2 1 11 2 1 1 l momm l l ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ )( )( )( 2 1 cm c c pr pr pr m . (2) in compact form [ ] )( 2 1 2 prj t=∇−= χβ , where is called jacobian matrix of the residue which is defined in eqn. 1. the onehalf coefficient is put to simplify the formulas. to improve the fit, we can shift the parameters j )( ci pr ,kkckc ppp δ+→ where kk tconsp βδ ×= tan = ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mp p p δ δ δ m 2 1 ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ × m tcons β β β m 2 1 tan . (3) the steepest descent strategy is justified, when one is far from the minimum, but suffers from slow convergence in the plateau close to the minimum, especially in the multi-parameter space. logically we would like large steps down the gradient at locations where the gradient (slope) is small (near the plateau) and small steps when the gradient is large not to rattle out of the minimum. moreover, it has no information about the scale or the value of the constant and one can see that kk tconsp βδ ×= tan has a problem with the unit dimensions. 1.3. newton’s method newton's method is an algorithm used for finding roots of equations in one or more dimensions. let us expand using a taylor’s series around the current points, , we get )(2 pχ∇ ( )mcccc pppp ,..., 21≡ )()( 22 cpp χχ ∇=∇ + higher order terms (4) [ ] +∇⋅ )(22 c t pp χδ mekelle university issn: 2073-073x 97 http://en.wikipedia.org/wiki/newton%27s_method http://en.wikipedia.org/wiki/algorithm http://en.wikipedia.org/wiki/root_(mathematics) http://en.wikipedia.org/wiki/equation http://en.wikipedia.org/wiki/dimension daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 =∇ )(2 pχ ⎥ ⎦ ⎤ ⎢ ⎣ ⎡ ∂ ∂ ∂ ∂ ∂ ∂ m ccc p p p p p p )( ,, )( , )( 2 2 2 1 2 χχχ l + + higher order terms, ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mmmm m m ααα ααα ααα l momm l l 21 22221 11211 ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mp p p δ δ δ m 2 1 where kckk ppp −=δ , [ ]mt pppp δδδδ ,,, 21 l= and α = ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ ∂∂ ∂ mmmm m m pppppp pppppp pppppp 22 2 22 1 22 2 22 22 22 12 22 1 22 21 22 11 22 χχχ χχχ χχχ l momm l l . note that k c p p ∂ ∂ )(2χ is the gradient vector of with respect to evaluated at and 2χ kp cp lx c kl pp p ∂∂ ∂ ≡ )( 2 1 22 χ α is the second order gradient vector of (is called hessian matrix) evaluated at . 2χ cp near the current points , we can approximate the value of up to the second order, as + . cp )( 2 pχ )()( 22 cpp χχ ∇=∇ [ ] )(22 c t pp χδ ∇⋅ assuming the chi-square function is quadratic around and solving for the minimum values of the parameters by setting , we get the update rule (the next iteration point) for newton’s methods: cp p 0)(2 =∇ pχ [ ][ ] )(2 c t pp χδα −∇= ⇔ ∑ = = m l klkl p 1 βδα (5) [ ] [ ] )(21 c t pp χαδ ∇−= − ⇒ [ ] )(21 cc ppp χα ∇−= − . (6) the chi function (which is quadratic) to be minimized has almost parabolic shape. the hessian matrix, which is proportional to the curvature of , is given by 2χ mekelle university issn: 2073-073x 98 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 lk c kl pp p ∂∂ ∂ ≡ )( 2 1 22 χ α = [ ] ⎭ ⎬ ⎫ ⎩ ⎨ ⎧ ∂∂ ∂ −− ∂ ∂ ∂ ∂ ∑ = lk ci cii ci k ci n i i pp pxf pxff p pxf p pxf ),( ),( ),(),(1 2 11 2σ (7) (the one-half here is also added for the sake of simplicity). the components klα of the hessian matrix in eqn. (7) depends both on the first derivative, k ci p pxf ∂ ∂ ),( , and second derivative, lk ci pp pxf ∂∂ ∂ ),(2 , of the basic function with respect to their parameters. the second derivative can be ignored when it is zero, or small enough to be negligible when compared to the term involving the first derivative. in practice, this is quite often small enough to neglect. if one looks at eqn. (7) carefully, the second derivative is multiplied by[ ]),( cii pxff − . for the successful model, this term should just be the random measurement error of each point. this error can have either sign, and should in general be uncorrelated with the model. therefore, the second derivative terms tend to cancel out when summed over time . inclusion of second derivative term can in fact be destabilizing if the model fits badly or is contaminated by outlier points that are unlikely to be offset by compensating points of opposite sign. so, instead of eqn. (7) we shall define the α-matrix simply as: i ∑ = ∂ ∂ ∂ ∂ ≡ n i l ci k ci i kl p pxf p pxf 1 2 ),(),(1 σ α which is equivalent to [ ] == jj tα ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∑∑∑ ∑∑∑ ∑∑∑ === === === n i m ci m ci i n i ci m ci i n i ci m ci i n i m cici i n i cici i n i cici i n i m cici i n i cici i n i cici i p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf p pxf 1 2 1 2 2 1 1 2 1 2 2 1 22 2 1 12 2 1 1 2 1 21 2 1 11 2 ),(),(1),(),(1),(),(1 ),(),(1),(),(1),(),(1 ),(),(1),(),(1),(),(1 σσσ σσσ σσσ l momm l l . (8) after computing, numerically or analytically, the gradient and hessian matrices for the current set of parameters, one can immediately move to the minimum by shifting the parameters ,kkk ppp δ+→ where the displacement vector kpδ is determined from the linear system derived in eqn. (5), i.e., mekelle university issn: 2073-073x 99 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mmmm m m ααα ααα ααα l momm l l 21 22221 11211 = ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mp p p δ δ δ m 2 1 ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mβ β β m 2 1 ⇔ = ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mp p p δ δ δ m 2 1 1 21 22221 11211 − ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mmmm m m ααα ααα ααα l momm l l ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mβ β β m 2 1 . (9) one of the problems associated with newton’s method (levenberg, 1944; kelley, 1999; madsen, et al., 2004; and lawson & r.j. hanson, 1974) is its divergence after successive iterations. at the instant when diverges we would like to retreat to its previous value and then decrease the steps, )(2 ppc δχ + )(2 cpχ pδ and try again. -8 -4 0 4 8 0 40 80 120 160 200 -8 -4 0 4 8 χ 2(p 1 ,p 2 ) 'n ew ton's m ethod' is efficient near the m inim um 's teepest d escent' is efficient far from the m inim um p 2p 1 figure 1. graph of the chi function: the chi-square (χ2) function versus two arbitrary experimental parameters p1 and p2. 1.4. the levenberg-marquardt algorithm in order for the chi-square function to converge to a minimum rapidly, one needs a large step in the direction along with the low curvature (near the minimum) and a small step in the direction with the high curvature (i.e. a steep incline). the gradient descent and gauss-newton iterations provide additional advantages. the lm algorithm is based on the self-adjustable balance between the two minimizing strategies: the vanilla gradient descent and the inverse hessian methods. mekelle university issn: 2073-073x 100 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 coming back to the steepest descent technique is dimensionless but 2χ kβ has the same dimension as kp 1 , as indicated in eqn. (3). the constant of proportionality between kβ and kpδ must therefore have the dimension of . for instance, if the parameter is measured in , then 2 kp kp kg kβ has obviously the units of so the constant must have a dimension of . therefore the unit cannot be the same for all parameters since they are generally measured in different units ( in seconds, in meter… in ampere). marquadt surmised that the components of the hessian matrix must hold at least some information about the order-of– magnitude scale and dimension. among the components of 1−kg 2−kg 1p 2p mp α -matrix the reciprocal of the diagonal elements have these dimensions. hence he suggested that this must set the scale of the constant. to avoid the scale becoming too large, it is divided by a dimensionless positive damping term, 1− kkα λ (being positive ensures that kpδ is a descent direction). eqn. (3) is then replaced by = ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mp p p δ δ δ m 2 1 ⎥ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ − − − 1 1 1 00 00 00 1 22 11 mm α α α λ l momm l l ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mβ β β m 2 1 . (10) in more compact form, .1 k kk kp βλα δ = in order to combine eqns. (9) and (10), marquardt defined a diagonally-enhanced new α′ matrix: ( ,1 )λδαα klklkl +=′ where the value of the kronicker delta function is given by such that ⎩ ⎨ ⎧ = ≠ = lkfor lkfor kl 1 0 δ ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ ′′′ ′′′ ′′′ mmmm m m ααα ααα ααα l momm l l 21 22221 11211 = ( ) ( ) ( )⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ + + + λααα αλαα ααλα 1 1 1 21 22221 11211 mmmm m m l momm l l (11) mekelle university issn: 2073-073x 101 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 where λ is a dimensionless constant, and klα is replaced with klα ′ in eqn. (5) which yields or ∑ = =′ m l kkl p 1 1 βδα . (12) = ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mp p p δ δ δ m 2 1 ( ) ( ) ( ) 1 21 22221 11211 1 1 1 − ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ + + + λααα αλαα ααλα mmmm m m l momm l l ⎥ ⎥ ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎢ ⎢ ⎣ ⎡ mβ β β m 2 1 for very small value of λ , the displacement vector ,kpδ obtained from eqn. (12) is close to the one, obtained by the pure inverse hessian technique, eqn. (9), which is a good step in the final stages of the iteration, near the minima. if (or very small), then we can get (almost) quadratic final convergence. however, if 02 =χ λ is very large, then the matrix klα ′ is forced in to being diagonally dominant, so eqn. (12) goes over to be identical to eqn. (10), this is good if the current iterate is far from the solution. it means that, by increasing the parameter λ we approach the ‘steepest descent’ limit (i.e. a short step in the steepest descent direction). thus, the damping term λ influences both the direction and the size of the step, and this leads us to make a method without a specific line search. to reduce the computational errors (especially near the minimum point), it is recommended to find the derivatives of the model function analytically. let’s first prepare the lm algorithm, with flow chart. the minimization process is iterative. one starts with a reasonably small value of ( px ,2χ ) λ . at every successful iteration: ( )22 curmew χχ < , it is reduced by a factor of 10, moving towards the ‘inverse hessian’ regime. otherwise it retreats to the ‘steepest descent’ regime by being increased by a factor of 10. the stop criteria are necessary to avoid an endless iteration cycle. when one or more combination of the following stopping criteria are satisfied, then the fitting process stops: i. when the total number of iterations entered by the user attains. ii. when the minimum value of to exit iteration attains. )(2 cpχ iii. when the absolute shift of the chi square, )()( 22 cc ppp χδχ −+ below some a certain threshold or decreases by negligible amount. the program can also be set to ‘pause’ when a start to diverge then continues after press enter key. )(2 ppc δχ + mekelle university issn: 2073-073x 102 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 figure 2. the lm algorithm with a flow chart. he update rule is used as follows. if the error goes down following an update, it implies that our uadratic assumption on is working and reduce t 2χ λq (usually by a factor of 10) to reduce the fluence of gradient descent. on the other hand, if the error goes up, we would like to follow the radient more and so in g λ is increased by the same factor. if the initial guess is good but does ot fall down to the required minimum value, we have to change the initial value of 2χ λn slightly. mekelle university issn: 2073-073x 103 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 2. implementation of the lm algo ithm in this paper gauss’s elimination and gauss’s jordan matrix inversion methods are used to determine the shift parameters. among the several tests made on real and complex non linear functions, only three examples are illustrated to see how much this method is effective and faster than the other methods. 2.1. test on real three dimensional wave func the first test is applied to two dimensional data coordinate r tion ( )ii yx , and data value where , e.g., at . table 1. experimental data for irregularly shaped surface. if 2101−=i )6.452,1,7(7 777 =−=−== fyxi ix -7 -6 -5 -4 -3 -2 -1 1 2 3 4 5 6 7 iy -7 -1.029 6.743 13.3 15.99 14.91 12.72 19.56 33.59 14.18 3.027 2.91 2.546 2.389 -8.428 -6 384 -7.211 0.544 6.464 7.324 2.644 -6.841 -20.33 4.615 5.203 10.67 13.85 11.29 4.334 -3. -5 -9.661 -5.837 -3.782 -5.371 -10.97 -22.67 -49.52 40.49 21.73 18.62 17.54 13.99 8.64 3.572 -4 -1 2-7.136 -8.94 -11.96 5.41 -18.64 -26.28 -52.5 54.98 26.54 16.56 12.09 9.181 8.176 8.796 -1.112 -6.983 -13.68 -17.6 -16.22 -15.65 -27.89 40.53 16.97 5.508 0.567 0.605 3.058 9.637 -3 -2 26 5.997 4.853 -0.665 -7.916 -11.2 -4.794 3.837 10.87 5.224 2.158 8.837 10.48 10. 4.33 -1 6.452 7.76 2.596 -0.96 10.17 22.71 41.83 30.86 21.57 19.46 13.81 14.99 11.16 0.942 0 1.905 14.72 12.53 6.545 21.22 31.66 47.46 47.46 31.66 21.22 6.545 12.53 14.72 -1.905 1 -0.942 11.16 14.99 13.81 19.46 21.57 30.86 41.83 22.71 10.17 0.96 2.596 -7.76 -6.452 -5.997 4.33 10.26 10.48 8.837 2.158 -5.224 10.87 3.837 4.794 11.2 7.916 0.665 -4.853 2 3 -9.637 -3.058 0.605 -0.567 -5.508 -16.97 -40.53 27.89 15.65 16.22 17.6 13.68 6.983 1.112 4 -8.796 -8.176 -9.181 -12.09 -16.56 -26.54 -54.98 52.52 26.28 18.64 15.41 11.96 8.94 7.136 5 -17.54 -18.62 -21.73 -40.49 49.52 22.67 10.97 5.371 3.782 5.837 9.661 -3.572 -8.64 -13.99 6 3.384 -4.334 -11.29 -13.85 -10.67 -5.203 -4.615 20.33 6.841 2.644 7.324 6.464 0.544 7.211 7 8.428 2.389 -2.546 -2.91 3.027 14.18 33.59 19.56 12.72 14.91 15.99 -13.3 6.743 1.029 mekelle university issn: 2073-073x 104 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 mekelle university issn: 2073-073x 105 re g o ri l s f e) n ic c t lu pxf (yellow) before iteration. figu 3 (a). raphs f expe menta value i (blu and umer al or ompu ed va es ),( c figure 3 (b). graphs of experimental values if (blue) and numerical or computed values ),( cpxf (yellow) after iteration daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 from the above results (table.1), one can easily see that the data (surface) follows the wave function having the form ( ) )cos()sin(1),,,,(), 322 3 1321 xypx p y ppppyxfp −− + == . the lm approach, in ord ))sin( ( yxp xf we have then made a fitting, using er to find the values of the parameters cos( ( )3,21 ,, ppp that best fit ),( pxf i with if (see fig. 3 (a) and (b)). ension is 2=q and the numbers of parameters are 3in this case the dim =m . after initializing ( )3,2p1 ,, pp the values found from the iteration are 0.02 =χ , ,0.71 =p 0.112 =p and . the function now have the from 0.543 =p ( ) )cos()sin(11 )cos( 54 1 )11sin( 7),( 2 xyx y y x yxf −− + = . as one can see from the above results, the lm model is highly useful when it is implemented to com -shaped surfaces. what is also important here is here that selecting an appropriate type of function (such as sine, power, decay, etc functions) and lambda. the shift parameters are not that much changed by normalized random errors only minimum of chi-function increases. hence, based on the above two figures (figs. 3 (a) and (b)), one can conclude that new equations/relations and modifications to the already existing formulas can be obtained from experimental data having disturbed/complicated surfaces. 2.2. test made on complex two dimensional function in e plicated llipsometery the complex ratio δψ== j s p e r r tanρ is measured, commonly expressed in terms of the two real parameters ψ and δ i.e. δψ= jetanρ . the inversion of this formula to get suitable value of real and imaginary part of the refractive index is some what ifficult to do analytically, and even numerically inversion of comp algorithm is not yet well developed. e homo s air and glass with r= d lex functions using lm let us consider an oblique reflection and transmission of optical plane wave at the planner interface between two semi-infinit geneou optically isotropic media complex index of refraction jkn + . the ratio of the complex reflection coefficient, n ρ , is the angle of incident by related to =ψ= δjetanρ ( ) ( ) θθ θθθsin 2⎢ ⎡ cossin sincos 22 2 22 0 jkn jkn r r +− ⎥⎦ ⎤ ⎣ −+− . mekelle university issn: 2073-073x 106 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 the algorithm has been tested on an actual data taken in a psa-ellipsometry on acrylic glass sample for a wave length of light nm450 . after successive iterations the following results has been recorded. table 2. experimental data and computed values of ρ and n . values found from the successive iterations thi tmeasuremen data coordinate ( )deg/ alexperiment error actual ),( nii θρρ − data values computed values iiθ if ρ= ),(),( npxf ici = θρ 1 52+j0 -0.11 j0.00134 1j1.31 -4.2445958e-05j2.2291672e-0 726-1.1721756e-0 77083e-03 5 2 54+j0 j0.00135 j1.3587392e-03 05+j8.7391818e-06 -0.06301-6.2998131e-02-1.1868775e3 55+j0 -0.03577j0 -3.5782781e-021.2781471e.00135 j1.3766416e-03 05+j2.6641530e-05 4 56+j0 -0.00847j0.00143 -8.5111084e-03j1.3926749e-03 4.1108578e-05j3.7325081e-05 n=4 ,1=q ,1=m j0.3 31 +== np c 10-ej7.0279005-09-1.1195837e chi = 9-1.32188e abs(chi) = 3-1ej2.90234271.50009620 n += initialization the real and imaginary part of the refractive index of the glass found from the iteration is 1.5000962 nr = and 2710.0029k = respectively. the fitted values of the reflection 0234 coefficient have up to 5 decimal precision (one can also get high precision by selecting perfection and machine error. plex function is, we only solve the derivative of appropriate lambda till the errors arise only form the experiment im the interesting thing doing with com ),( nθρ with respect to i.e. n dn nd ),(θρ to find and (not rn k rdn n ),(θρ and dk n ),(θρ ) . during interpolation and extrapolation, unlike the aitkens and lagrange interpolations, graphs erpolated using lm follow path (with ). int model the right little regression mekelle university issn: 2073-073x 107 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 40 55 60 65 70 -0.4 45 50 -0.5 -0.3 -0.2 .1 0.0 0.1 0.2 0.3 0.4 -0 -0.0015 -0.0014 -0.0013 -0.0012 -0.00 -0.0010 * indicates expe 271) rimental (where n=1. j0.00290234 extrapolated graph for the complex function ρ(θ,n) value 5000962+ r ea l o f ρ ( ρ r ) 11 im ag in ar y of ρ ( ρ i ) angle of incident θ/deg figure 4. extrapolated graph for the complex function ),( nθρ with * and ▪ representing experimental and numerical values respectively. 2.3. test on complex two dimensional power unction the third test was made on complex three dimensional power functions (their derivatives are logarithmic functions). consider the following experimental data: f table 3. experimental data on 2d power functions. i ix iy if 1 6+j2 1j 6 151.1271 j 41.47818 2 5+j8 29+j 0 -318.893 j 710.7169 3 -3+-j0.5 -7+j 1 34.97808 j 96.72046 4 -4+j 2 0+j 5 61.8854 j 24.1816 5 -5+j 5 -9.9j 3 260.2891 j 413.5324 6 -6j 1 -4+j 1 14.13067 j 120.9102 n =6 mekelle university issn: 2073-073x 108 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 ( ) 434321 21,,,,, pxypyxppppyxf pp +++=the data is fitted with the function . for this case the value of and2=q 4=m . during initialization of the parameters with , jp 5.021 −= jp 5.022 += , 5.0023 jp += and 5.024 jp += (equivalent to ), the appropriate value of5.0,5.0,5.0,5.0,2,2,2 −=cp λ used near is . figure 5 (a). graphs of the experimental and nume cal data at different number of iterations. figure 5 (b). graphs of the experimental and numerical data at different number of iterations. 001.0 0012.0 ri mekelle university issn: 2073-073x 109 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 figure 5 (c). graphs of the experimental and numerical data at different number of iterations. figure 5 (d). graphs of the experimental and numerical data at different number of iterations. the function becomes ( ) ( ) ( ) 39505.0,,,,, 26.014321 jxyjyxppppyxf j +−+−++= − . from the figs. 5 (a)-(d), we can see that the lm is not affected by the order of the data (ascending or descending). mekelle university issn: 2073-073x 110 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 based on the above results we can conclude that the lm algorithm is popular method and has the following advantages (i) the parameters converge rapidly around the minimum in multi dimensional surfaces with complicated landscapes. (ii) even though the initial guess is poor, lm fits partly/most of the parameters to make fresh start. (iii) the convergence speed needed to reach the minimum, is not significantly influenced by the number of parameters. (iv) the shift parameters are not that much changed by normalized random errors. only the minimum of the chi-function increases. (v) normalized random errors do not bring much change on the convergence speed, etc. like any other non-linear optimization techniques, the lm algorithm method in finding global a better guess). 3. summary we extended the framework of the lm algorithm to real and complex multi-dimensional functions. the results show that lm is very efficient when gradient descent and newton’s methods separately failed to converge. in this paper we developed two programs (one for real and the other for complex or imaginary values) that work for any number of parameters, any number of dimensions and coordinate systems: cartesian, curvilinear etc. we believe that the algorithm also provides a concert support when someone wants to make a check at the instant of a fitting or when solving complex functions. last but not least the lm method develops user’s trust on the algorithm during fitting complicated surfaces and/or graphs. 4. acknowledgements we would like to acknowledge the moral support of all our staff members at the department of ph sciences, mekelle university. we are also gratef l for the referees (internal and external) and the ethiopian journal of science for their critical and co minimum is not guaranteed (this however can be secured by initializing parameters with ysics and the material support of the same department, college of natural and computational u editors of the momona nstructive comments and to the opportunity the journal has given us to publish our paper in the first volume. mekelle university issn: 2073-073x 111 daniel & alem (mejs) volume 1 (1): 95 – 112, 2009 5. references arumugam, m. 2003. emprr: a high-dimensional-based piecewise regression algorithm. pp. avriel, m. 2003. nonlinear programming: analysis and methods. dover publishing. isbn 0bates, d s, d. g. 1988. nonlinear regression and its applications. wiley, new york. press, new york,. kelley, 1-433-8. ampton, m. 1997. damping-undamping, strategies for the levenberg-marquardt nonlinear ares method. computers in physics journal, 11(1): 110 – 115. niversity of denmark. arquardt, d. 1963. an algorithm for least-squares estimation of nonlinear parameters. mathematics, 11: 431–441. 4-16. 486-43227-0. . m.& watt box, m. j., davies d. & swann, w.h. 1969. non-linear optimisation techniques. oliver & boyd. coope, i. d. 1993. circle fitting by linear and nonlinear least squares. journal of optimization theory and applications, 76 (2), plenum gill, p. r., murray, w. & wright, m. h. 1981. the levenberg-marquardt method §4.7.3 in practical optimization. academic press, london, pp. 136-137. c. t. 1999. iterative methods for optimization, siam frontiers in applied mathematics, 18, isbn 0-8987 l least-squ lawson, c.l. & hanson, r.j. 1974. solving least squares problems. prentice-hall. levenberg, k. 1944. a method for the solution of certain non-linear problems in least squares. the quarterly of applied mathematics, 2: 164–168. lourakis, i. a. 2005. a brief description of the levenberg-marquardt algorithm implemented by levmar, institute of computer science foundation for research and technology hellas (forth), vassilika vouton. madsen, k., nielsen, h.b. & tingleff, o. 2004. methods for non-linear least squares problems, informatics and mathematical modeling. 2nd edition, technical u m siam journal on applied mekelle university issn: 2073-073x 112 tadesse et al (mejs) volume 1 (2): 4-16, 2009 intestinal helminthes infections and re-infections with special emphasis on schistosomiasis mansoni in waja, north ethiopia *tadesse dejenie1, tsehaye asmelash2 and mekonnen teferi1 1department of biology, college of natural and computational sciences, mekelle university, po box 231, mekelle, ethiopia (*taddej2002@gmail.com) 2department of parasitology and microbiology, mekelle university, po box 231, mekelle, ethiopia abstract to determine the status of infection and re-infection caused by schistosoma mansoni in a small town of waja, northern ethiopia, stool samples were collected from primary school children in two rounds (in mid june and mid september 2004) and were examined using the kato thick smear method. in addition, water bodies that might serve as biotopes for the intermediate host snails were located and searched using scoops. during the first survey, the prevalence of s. mansoni among the 224 children (119 male and 105 females) sampled was 27.1%. s. mansoni prevalence increased from 27.1% to 36.4% (p< 0.05), during the 2nd survey, three months following the treatment of the positive cases. similarly, an increase in the prevalence of t. trichiura was observed (from 16 to 30.7%), whereas that of ascaris lumbricoides decreased during the second survey (from 50 to 42.8%) (p<0.003). s. mansoni prevalence was higher in males than in females during both surveys (35.3% vs 18.1% 1st survey; and 51% vs 32.6% in the 2nd survey (p < 0.05). the profile of infection with s. mansoni in the various age groups showed a peak infection rate in the age group 15-19 years (41.2%) followed by the age group 10-14 (24%) and the least affected were the 5-9 age groups (18.5%) (p<0.002). the risk of decreasing schistosomiasis mansoni is discussed and the possible prevention and control measures are suggested. key words: schistosoma mansoni, infection, re-infection, intensity 1. introduction in many developing countries, one of the most prevalent and most important helminthes is the blood flukes, schistosomes (razendaal, 1997). dorit, et al. (1991) reported that schistosomiasis is considered to be in par with malaria and hookworm infections that cause serious illnesses in humans. in agreement with this, ruppert and barnes (1994) pointed out that schistosomiasis can be an important disabling human disease, which may also result in death. schistosomiasis is one of the most important human parasitic diseases in terms of socioeconomic and public health importance in tropical and subtropical areas. it ranks second to malaria, the most prevalent water borne disease and one of the greatest risks to health in rural areas of developing countries (rozendaal, 1997). © cncs mekelle university tadesse et al (mejs) volume 1 (2):4-16, 2009 reports of who showed that 74 tropical countries are endemic for schistosomiasis and over 200 million people in the rural and agricultural areas are estimated to be infected and 500 to 600 million people are considered to be at risk of becoming infected (rozendaal, 1997). schistosomiasis is responsible for 50,000 deaths annually (dupre et al., 1999). in ethiopia, the optimum range for distribution of s. mansoni has been reported as 1500 to 2000masl (lo et al., 1988). in tigray, various studies have been conducted on the prevalence, distribution and infection foci of schistosoma mansoni infection (alemayehu et al., 1998; birrie, 1994; woldemichael and kebede, 1996), but none of them studied re-infection of s. mansoni infections. in a recent study, 87% infection was recorded for tumuga (tadesse and beyene, 2009), which is 1450mas and only five kilometers far from waja. this might be attributed to the higher water contact of the children in timuga. waja-wuha, which is a nearby water body has high density of cercaria-infected snail intermediate host. this is considered a cause for the situation the preventive measure to be taken depends on our understanding of the extent of the problem in the different regions of the country. hence, a survey of schistosoma mansoni infection and re-infection in waja, northern ethiopia was carried out. this study intends to assess the prevalence of intestinal schistosomiasis so as to recommend the effective means of control in waja. thus, the objectives of this research is a) to examine the present epidemiological profile of schistosoma mansoni and identify new endemic foci, b) to have basic information on infection and re-infection of schistosoma mansoni in waja and c) to identify water bodies with the intermediate hosts biomphalaria pfeifferi. 2. materials and methods 2.1. description of the study area the study was conducted in a small town, waja, located in southern tigray, near the border between tigray region and the amhara regional state. waja is found between latitude 120 and 150 n, 380 10′ and 400e longitude. lying at an average altitude of 1450 masl, the town has about 5000 inhabitants; most of them are engaged in subsistent agriculture. it has one primary school and a health centre. © cncs mekelle university 5 tadesse et al (mejs) volume 1 (2):4-16, 2009 2.2. study design the study involved two longitudinal surveys in a randomly selected sample of children aged 6-14 years from the only primary school in the town. the primary school children were selected to represent the community they live in as prevalence of infection in school-aged children, which can be used as an index for assessing community prevalence (guyatt et al., 1999). the first survey was conducted in mid july, 2004 and all children who were found positive for any intestinal parasites were treated. three months later (mid september 2004), we re-visited the school and re-examined the same children that could be traced. in other words, those who were negative and the positives (after being treated) were used as a cohort for the re-infection study (second survey). at the beginning of the study, the objectives were explained to the school principal, other concerned authorities and students. students who volunteered to participate and fulfil the following inclusion criteria were listed as prospective donors of faecal sample: • live in the town, never had gone away far from waja; • never had treatment for any intestinal helminth infections during the last 3 months; • students attending classes at the time of sample collection. from the list containing the names of prospective donors, a total of 224 students were selected using random start to identify the sample population (only during the first sampling). 2.3. sample collection and processing after the lists of donors were drawn up, students were supplied with plastic sheet to bring about 5 gm of faeces. in the first survey (n= 224) and in the re-infection study, only 194 students stool samples (31 students were absent from school during the second sampling collection) were processed by kato thick smear technique (peters et al., 1980). the prepared slides were transported to mekelle university for microscopic examination, for further cross checking and quality control. positive samples were rated as eggs per gram of stool in order to determine the intensity of infection. in this infection and re-infection study, prevalence was estimated from the proportion of infection as compared with the total population examined. intensity of infection was estimated from the number of eggs per gram of faeces (epg). egg count for the different parasites was used as recommended by who (razendaal, 1997) for the purpose of © cncs mekelle university 6 tadesse et al (mejs) volume 1 (2):4-16, 2009 classification of intensity of infection in the community into light, moderate and heavy infections. cut off value for classification of intensity of infection by montresor et al. (1999) was used. accordingly for s. mansoni infection is: light = 1-99epg, moderate = 100-399epg, heavy = >400 epg. to determine the occurrence and distribution of the snail intermediate hosts, live snails and shells were collected by scooping from waja wuha (the big river on the northern side of waja town) in order to establish whether or not local transmission occurs. biomphalaria pfeifferi, the main intermediate vector for s. mansoni were placed in a transparent vial and placed in a sunny area to observe the shading of motile cercaria of s. mansoni. all positive cases for any type of intestinal parasite were treated with appropriate antihelminthic drugs. those with s. mansoni were treated at each subsequent sampling with praziquantel 40 mg/kg body weight, single dose. data were entered into a computer and analyzed using spss version 11.1. the chi-square test of significance was applied. significance was determined on a 5% significance level (p-values < 0.05). 3. results a total of 224 (119 male and 105 female) students were examined in the first screening for intestinal helminthes. of these, 194 (86.6% 103 males, 92 females) were traced and examined during the second survey, which was conducted three months later. at base line (first round), over 65% of the schoolchildren were infected with one or more intestinal helminthes. this has increased to 72.2%, three months following the treatment of positive cases (p < 0.03) (table 1). in other words, fecal examination after three months of the initial treatment indicated that 72.2% of the study population remained infected or became re-infected by this time (there is evidence from recent study of efficacy of praziquantel in treating s. mansoni infected individuals by tadesse et al. unpublished data). just over 27% of the school children were found infected with s. mansoni during the first round (baseline) of the study. the prevalence of s. mansoni infection showed a significant increase during the second survey (from 27.1% to 36.4% (p < 0.05) (fig. 1). we did not do © cncs mekelle university 7 tadesse et al (mejs) volume 1 (2):4-16, 2009 water contact studies of the school children. nevertheless, the data showed that re-infection rates were not improved following single treatment and natural re-exposure. table 1. proportion of the students who were positive for one or more intestinal helminth parasite species in both infection and re-infection sampling in waja, 2004. female male total sampling period examined positive no (%) examine positive no (%) examine positive no (%) june 2004 sampling 105 69 (38.8) 119 78 (34.82) 224 147 (65.62) sept. 2004 sampling (after initial treatment) 92 60 (30.9) 103 80 (41.2) 194 140 (72.16) similarly, an increase in the prevalence of trichuris trichiura infection was observed (from 16% to 30.7%). at baseline, the prevalence of a. lumbricoides was 50%, but it decreased to 42.8% in the re-infection study (p< 0.003) (fig. 1). figure 1. infection and re-infection of s. mansoni, a. lumbricoides and t. trichiura. both at baseline (35.3% males &18.1% females) and during the second survey (51% males and 32.6% females), s. mansoni prevalence was significantly higher in males than in females (p<0.05) (fig. 2). nevertheless, there was no significant difference in prevalence of the other intestinal parasites between the sexes, both during the first and second surveys. © cncs mekelle university 8 tadesse et al (mejs) volume 1 (2):4-16, 2009 figure 2. s. mansoni infection and re-infection in waja school children with respect to sex. the number of students examined with respect to the age group was 27 in the age group 5-9, 146 in the age group 10-14 and 51 in the age group 15-19 years for the first sampling. for the re-infection, the number of students examined was 24, 126 and 44, respectively. figure 3. s. mansoni infection and re-infection in waja school children with respect to age. at baseline, the prevalence of s. mansoni infection prevalence was highest in the age group 15-19 (41.2%) (p< 0.002) followed by the age group 10-14 (24%), and in 5-9 years © cncs mekelle university 9 tadesse et al (mejs) volume 1 (2):4-16, 2009 (18.5%) (fig.3). during the follow up survey, however, the peak was observed in the age group 5-9 (58.5%) followed by the 15-19 (45.5%) and the least infection rate was in the age group 10-14 (38.1%) (p<0.08). s. mansoni intensity epg 0-99 100-399 >400 % in te ns ity 0 5 10 15 20 25 30 infection reinfection figure 4. intensity of s. mansoni infection in epg (eggs per gram of faeces). the intensity of s. mansoni infection was compared at baseline and after 3 months following the treatment of positive cases. as indicated in fig. 4, higher intensity was observed during the second survey. it can be clearly seen that both moderate and heavy intensity of infection was observed during the second sampling survey (p<0.02). besides, higher intensity of s. mansoni infection was observed in males than in females at both surveys (p<0.005) (fig. 5). a. infection epg 1-99 100-399 >400 % in te ns ity 0 5 10 15 20 25 30 35 male female b. reinfection epg 1-99 100-399 >400 0 5 10 15 20 25 30 male 2 female 2 figure 5. intensity of s. mansoni infection among sexes in epg (eggs per gram of feces). key: light infection = 1-99 epg, moderate infection = 100-399epg and heavy infection = >399epg, abbreviations: a = s. mansoni infection intensity, b = s. mansoni re-infection intensity. © cncs mekelle university 10 tadesse et al (mejs) volume 1 (2):4-16, 2009 the intensity of s. mansoni infection with respect to age revealed that the peak for light infection was in the age group 15-19 (p < 0.03) (fig. 6) whereas in the re-infection survey, there was significant difference among the age groups (p > 0.05). b. intensity reinfection age in years 5-9 10-14 15-19 % in en si ty 0 5 10 15 20 25 30 35 light moderate heavy a. inensity of infection 5-9 10-14 15-19 % in te ns ity 0 10 20 30 40 50 light moderate heavy age in years figure 6. intensity of s. mansoni infection with age in both infection and re infection key: light infection = 1-99epg, moderate infection = 100-399epg and heavy infection = >399epg, abbreviations: a = s. mansoni infection intensity, b = s. mansoni re-infection intensity 4. discussion intestinal helminthic infection is one of the major health problems in ethiopia. the knowledge of the prevalence and distribution of intestinal helminth infection has been gradually increasing. various studies have been conducted on all intestinal parasites spp. or specifically on schistosoma mansoni infection in ethiopia. in tigray, a variety of surveys have been done (tadesse and beyene, 2009; mc-connel and armstrong, 1976; birrie et al., 1993; woldemichael and kebede, 1996; alemayehu et al., 1998; kiloos et al., 1978). however, prevalence studies in relation to infection and re-invention is limited or none. the present study aimed at determining the infection and re-infection of s. mansoni in waja. overall prevalence of intestinal helminth parasite infections was 65.62% and 72.16% in both infection and re-infection respectively. the prevalence of s. mansoni was also consistent, that is, 27% and 34% in infection and re-infection study respectively. the © cncs mekelle university 11 tadesse et al (mejs) volume 1 (2):4-16, 2009 results show that in spite of the decrease in the prevalence of schistosoma mansoni after treatment, increase in rate during re-infection was observed. this high rate of infection after treatment could be attributed to the fact that the re-infection sampling was done immediately after the rainy and hot season, which might have some impact in facilitating the rate of prevalence of re-infection (birrie et al., 1998). besides, soon after the first sample collection, schools were closed and students didn’t go to school rather they were engaged in farm and related activities that might increase the chance to have contact with water bodies. on the other hand, water and vegetation nearby water bodies increase during the rainy season, and flood (flashing the water bodies) decrease with the decrease of rain beginning mid of august. the relatively high temperature, humid environment and presence of water may lead to an increase in the intermediate host population, which on the other hand increases the production of cercaria (the infective stage of the s. mansoni). this might indicate that more effort is needed than only treating infected individuals to achieve a continuous drop in prevalence, incidence, and re-infection rates. in s. mansoni infection, more males were infected than females in both infection and reinfection studies. similar findings were reported by different investigators (birrie et al., 1994; woldemichael and kebede, 1996; lemma, 1969). but in the recent finding in tumuga (tadesse and beyene, 2009) sex related difference in infection was not consistent. the limitation of the present work is the limited age range of the study population, because the target population was primary school children with the age range of 5-19 years. even then, significant age related differences could be discerned. the peak of s. mansoni infection was seen in the age group 15-19 and then followed by the age group 59 and least infection was in the age group10-14. similar pattern of age related difference was also observed in both infection and re-infection studies. other reports in contrary to this, indicate that the peak of infection in the age group 10-14 and the least peak in the age group 5-9 (which is usually associated with low water contact of this age group) were in different parts of the country (erko, 1988; birrie et al., 1997) and from the same region (tadesse and beyene, 2002; alemayehu et al., 1998). © cncs mekelle university 12 tadesse et al (mejs) volume 1 (2):4-16, 2009 analysis of the intensity of infection in the age groups showed the peak of light infections to be in the age group 15-19. the intensity decreased in the age group 5-9 and the least affected were 10-14 years old children. this is in contrary to the reported finding in tumuga (tadesse and beyene, 2009) and bahir dar that showed the peak of all light, moderate and heavy intensity of infection in the age group 10-14 (erko et al., 1991). on the other hand, it was the 5-9 age group, which was harboring the highest s. mansoni infection. though this result is contrary to different reports (tadesse and beyene, 2009; erko et al. 1991), this observation might be correct due to the fact that they will have the highest contact with water if children once start contacts with infected water. besides, abel et al. (1991) reviewed an evidence suggesting that for individuals having frequent contacts with water infested with the cercaria of schistosoma mansoni, both infection intensities and re-infection after treatment depend, in large part, on their intrinsic susceptibility/resistance to infection, suggesting a role of genetic factors. these are age groups which have the responsibility to look after cattle which gives ample time for water contact, increasing the likelihood of infection. due to the high susceptibility and high contact with infected water, all children including age groups 5-9 year are considered to be equally susceptible to infections of s. mansoni. in a. lumbricoides infection, younger children had higher infection rates than the older ones. this indicated that younger children were more exposed to infections, which could be transmitted due to the contamination of the environment, especially the soil where the children usually played in the open fields and ate food without washing hands. thus, as age increases, susceptibility to intestinal nematode infection decreases possibly due to improved personal hygiene as reported by alemayehu et al. (1998). in general, the result showed that children are much more rapidly re-infected than adults as reported in other studies also (tadesse and beyene, 2009; erko et al., 1991). in addition, from this study it can be concluded that single time mass treatment may not be effective means of controlling schistosomiasis mansoni in an endemic area due to very frequent re-infection and different risk factors that expose to infections. this finding demonstrates that additional measures such as proper environmental sanitation and vector control are needed to control human schistosomiasis. besides, treating infected individuals, continuous cleaning of the canals to eliminate the snail © cncs mekelle university 13 tadesse et al (mejs) volume 1 (2):4-16, 2009 intermediate host of s. mansoni is recommended (agula’i, which is found in tigray region, with more than 100 years of traditional irrigation practice had no snail intermediate host of s. mansoni, could be taken as vivid evidence, tadesse and tsehaye in preparation). so the pattern of community canal-water interaction may have a role in many traditional, cultural and occupational factors that should be taken into consideration in any effective long-term control programme. 5. acknowledgments this study was financially supported by the flemish institutional university cooperation (vlir), through the vlir inter-institutional cooperation between mekelle university and flemish universities. we especially thank students and teachers of waja primary school for their support during data collection. 6. references abel, l., demenais, f., prata, a., souza, a. e & dessein, a. 1991. evidence for the segregation of a major gene in human us-susceptibility/resistance to infection by schistosoma mansoni. am. j. hum. genet., 48:959 970. alemayehu, t., ye-ebiyo, y., ghebreyesus, t. a & wtten, k. h. 1998. malaria, schistosomiasis, and intestinal helminths in relation to micro-dams in tigray, northern ethiopia. parassitologia., 40: 259-267. birrie, h. 1986. survey of schistosomiasis mansoni in borkena river basin, ethiopia. ethiop med j., 24: 159-168. birrie, h., ayele, t., tedla, s & abebe, f. 1993. transmission of schistosoma mansoni in three ecological settings in ethiopia. i. epidemiological aspect. ethiop. j. health dev., 7: 63-69. birrie, h., weldemichael, t., redda, a & chane, t. 1994. the status of s. mansoni and snail hosts in tigray and northern wollo regions, northern ethiopia. ethiop med j., 32:245-254. birrie, h., medhin, g., erko, b., beshah, g & gemechu, t. 1997. intestinal helminth infections among the current residents of the future finchaa sugar plantation area, western ethiopia. ethiop. j. health dev., 11: 219-228. © cncs mekelle university 14 tadesse et al (mejs) volume 1 (2):4-16, 2009 birrie, h., tedla, s., tilahun, g., kloos, h & eshete, h. 1998. schistosomiasis and its distribution in ethiopia and eritrea. in: h. burie, s. tedla and l. jemaneh (eds), schistosomiasis in ethiopia and eritrea, 2nd edition, institute of pathobiology, addis ababa university, 29 – 86 pp. chandiwana, s.k. christensen, n.o & frandsen, f. 1987. seasonal pattern in the transmission of schistosoma haematobium, s. mattheei and s. mansoni in the highland region of zimbawe. acta tropica, 44 (4): 433444. dorit, r.l, walker, w.f & barner, r.d. 1991. zoology. tokyo, sounders college publishing. toronto london sydney, p. 632. dupre,l., herve, schacht, a.,capron, a & riveav, g. 1999. control of schistosomiasis pathology and praziquantal treatment. j. inf. dis., 180: 454-463. erko, b. 1988. epidemiology of schistosomiasis in bahar dar, m. sc. thesis, addis ababa university, 60-67 pp (unpubl.). erko, b., tedla, s & petros, b. 1991. transmission of intestinal schistosomiasis in bahr dar, northwest, ethiopia. ethiop. med. j., 29: 199-211. fuller,g.k., lemma,a & haile, t. 1979. schistosomiasis in omo national park of south west ethiopia. am.j.trop. med. hyg., 28:526-530. guyatt, h.l., brooker, s & donnelly, c.a.1999. can prevalence of infection in school aged children be used as an index for assessing community prevalence? parasitology, 118 (3):257-268. kiloos, h., lemma, a & desole, g. 1978. schistosoma mansoni distribution in ethiopia: a study in medical geography. ann. trop. med. parasito., 72: 461-470. kiloos, h., lemma, a., kibru, b., gebre, a., mazengia, b., feleke, g & desole, g. 1980. intestinal parasitism in migrant farm labour populations in irrigation schemes in the awash valley, ethiopia, and in major labour source areas. ethiop. med.j., 18: 52-61. kiloos,h., desole, g & lemma, a. 1981. intestinal parasitism in seminomadic pastoralists and subsistence farmers in and around irrigation schemes in the awash valley, ethiopia, with especial emphasis on ecological and cultural associations. soc. sci. med., 15: 457 469. © cncs mekelle university 15 tadesse et al (mejs) volume 1 (2):4-16, 2009 lo, c.t., kloos, h & hailu, b. 1988. schistosomiasis. in: zein ahmed and h. kloos (eds.), the ecology of health and disease in ethiopia,. addis ababa: empda press, 196207 pp. mc-connel, e & armistrong, j.c. 1976. intestinal parasitism in fifty communities on central plateau of ethiopia. ethiop. med. j., 14: 159-168. montresor, a., gyorkos, t. w., crompton, d. w. t., bondy, d. a. p & savioli, l. 1999. monitoring helminth control programs. guide line for monitoring the impact of control programs aimed at reducing morbidity caused by soil-transmitted helminthes and schistosomes, with particular reference to school age of children. who/ cds / cpc / sip/99.3. geneva, who. peters, p.a., alamy, m.e., warren, k.s & mahmoud, a.a.f. 1980. quick kato smear for field quantification of schistosoma mansoni eggs. am. j. trop. med. hyg., 29 (2):217219. ritchie, l. s. 1948. an ether sedimentation technique for routine stool examination. bull. u.s. army med. dep., 8: 326-329. rozendaal, j .r. 1997.vector control methods for use by individuals and communities. geneva, who :337356. ruppert, e. e & barnes, r.d. 1994. invertebrate zoology. 6th ed. sounders college publishing. toronto london sydney tokyo, p. 245. tadesse dejenie & beyene petros. 2009. irrigation practices and intestinal helminth infections in southern and central zones of tigray. ethiop. j. health dev., (in press) tedros, g., mitiku h., witten, k., asfaw g., ambachew m., mekonnen y., hayly, t., lindsay, s & byass, p. 1999. community based incidence survey of schistosomiasis, report. (unpubl.). woldemichael, t & kebede, a. 1996. newly identified endemic areas of schistosomiasis mansoni in tigray, north ethiopia. ethiop. med. j., 34:73-81. © cncs mekelle university 16 © cncs mekelle university geological and geochemical variations in mid-tertiary ethiopian flood basalt province, maychew, tigray region, ethiopia kurkura kabeto* department of earth science, college of natural and computational sciences, p.o. box 231, mekelle university, ethiopia (*kurkura57@yahoo.com) abstract the paper presents the results of a comprehensive major element, trace element, and sr-nd-pbhf isotopic study of mid-tertiary volcanic sequences from the northwestern flood basalt province in ethiopia. the volcanic rocks studied range in composition from basanites, alkaline basalts, and ankaramites, which form the 1st three sequences at the base associated with basaltic agglomerate (sequence 1, 2 and 3) to transitional and tholeiitic basalts and picrites confined to the upper three sequences (sequences 4, 5 and 6). sequence 5 is bimodal with intermediate-felsic pyroclastic rocks intercalating the transitional-tholeiitic basalts. there is a good correlation of sequences with geochemical enrichments, such as an increase la/lun with tio2, and decrease in al2o3 and sio2 towards the base. the smooth increase of la/lun ratios in lower sequences reflect the general decrease of degree of partial melting that sampled heterogeneous packages of mantle plume materials. in the sr-nd isotopic diagram two clusters are formed one with restricted and lowsr(0.70356-0.70345) and nd(0.51290-0.51284) isotopic compositions, defined by sequence 1, and the other cluster with relatively higher 87sr/86sr (0.7052-0.7036) and 143nd/144nd (0.51296-0.5127) isotopic compositions defined by samples from sequence 2, and most other sequences with little scatter. the pb-isotopic compositions vary systematically within each sequence (from base to top), and each sequence clustered systematically in a different pb– pb– isotopic space with the highest 206pb/204pb (19.10-19.30) and 207pb/204pb (15.60-15.65) measured in sequence 1, quite differently from other sequences and from previously reported for northwestern ethiopian flood basalt province, and the lowest 206pb/204pb (18.20-18.56) and 207pb/204pb (15.51-15.55) measured in sequence 4. sequence 2 and 3 lavas display a similar 206pb/204pb and 207pb/204pb ranges falling between sequence 1 and 4. in contrast, sequence 6 samples displayed towards higher 206pb/204pb than sequence 2, 3, and 4, but with lower and higher 207pb/204pb than sequence 1 and 5 respectively. the lavas of sequence 1 and 4 have relatively less radiogenic 176hf/177hf than other sequences with slight scatter. the systematic geochemical variations in lavas are remarkable and reflects three mantle end component mixing with minimal crustal in put as a fourth component. the enriched sequence 1 has very similar geochemistry to himu-type ocean island basalts (oibs), and this end member ascribed to be the most enriched afar plume component 1, which is the most enriched afar plume component during initial continental break. the second enriched component is defined by sequence 2 and 3 samples and may reflect the second enriched component in ethiopian flood basalt, previously reported for the high-ti2 basalts assumed to be the enriched afar plume component, whereas the third component is the depleted component defined by sequence 4 partly overlap the range previously reported for low-ti basalts. keywords: flood basalts, geochemistry, sr-nd, pb-pb, hf-hf isotopes, afar plume, partial melting, crustal input. kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 5 1. introduction the mid-tertiary (~30 ma) ethiopian continental flood basalts form part of the larger afroarabian igneous province, which is related to the afar plume and the red sea-gulf of aden ethiopian rift triple junction. maychew, the area, of present study (fig. 1) forms part of the high-ti basalts of ethiopian flood basalt province. rocks here are composed of alkaline lavas (basanites, basalts, and ankaramites, with basaltic agglomerate) at the base, felsic volcanics in the middle, and transitional to tholeiitic mafic lavas at the top of the transitional sequence. pik et al. (1998, 1999) have classified the north-western ethiopian flood basalts into three distinct geochemical groups based on trace element and ti concentrations: low-ti basalts (lt), high-ti1 (ht1) basalts and high-ti2 (ht2) basalts. they recognized a suite of ‘low-ti’ (lt) basalts restricted to the northwestern part of the province (fig. 1) assumed to be derived from depleted mantle. they are characterized by relatively flat ree patterns and lower ti and incompatible trace element concentrations. alkali basalts found to the south and east of the province on the other hand show higher concentrations of incompatible elements and more fractionated ree patterns and related to the so-called ‘high-ti’ basalts (ht1 and ht2). in western ethiopian plateau, up to 2 km thick predominantly mafic lavas with minor felsic pyroclastics (fig. 1) make up the northern part of the ethiopian flood basalt sequence (e.g., hoffman, 1997; ayalew et al., 2002) and cover an area of ~ 106 km3 (rochette et al., 1998). the maychew area is located in the northern eastern corner of the western ethiopian plateau and covers an area of about 100 km2. at present there is no geochronological data available for maychew lavas to verify the sequential variations, but the earlier k-ar whole-rock age dating of basalts collected from 110 m and 140 m above base in maychew area gave 26.2 ma and 25.7 ma (jones, 1976), respectively. however, such a young age compared to the current refined and accepted mineral 40ar/39ar age of 30.9 and 29.2 ma for the northwestern ethiopian continental flood lavas (hofmann et al., 1997; coulie et al., 2003; kieffer et al., 2004) could be related to the unrecognized argon loss or gain in these intensely weathered formations. hence, at present 31-29 ma is accepted as a reasonable estimate for the maychew flood basalt sequence. as shown in figure 1, the maychew area is located between the adigrat area and chinese road section (a and c, in fig. 1) and the samples collected from these areas are dated between 31-29 ma. moreover, recently kieffer et al. (2004), dated plagioclase separate from alkaline picrite from bora kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 6 mountain (b in fig. 1, close to maychew area) at 30.99±0.13 ma. the dated sample is taken from lateral variation of ankaramite/ picrite of sequence 2 (fig. 2). the younger age of 29.2 ma (hofmann et al., 1997) is obtained from ignimbrite layers exposed at the topper part of the sequences, which is equivalent to sequence 5 described at maychew area. figure 1. location map of nw ethiopian plateau, afar rift and main ethiopian rift (from kuster et al., 2005). the approximate broken line separates the low-ti and high-ti flood basalt province (pik et al., 1998). despite a relatively large chemical database for the southern and western ethiopian plateau volcanics, there are still many parts of the plateau magmatism that are not studied. most studies on ethiopian rift and plateau magmatism have been carried out at a regional scale (pik et al., 1999, kieffer et al., 2004), and detailed investigations on single sections of the plateau are scarce. moreover, lack of a detailed geological map of any particular section of the ethiopian flood basalt province makes it difficult to correlate much of the existing high quality geochemical data from various parts of the ethiopian flood basalt province. this paper presents kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 7 geology map of part maychew area dominated by high-ti basalts (figs.1; 2 & 3). systematic rock sampling of selected sections was carried out. they are analysed for whole-rock major and trace elements, sr, nd, pb, and hf isotopic data using suitable procedures (nakamura et al., 2003) at pheasant memorial laboratory of the institute for study the earth’s interior, okayama university at misasa. the large data set of the volcanics thus obtained is discussed in the paper in addition to geology and stratigraphic sequence of the flows. 2. stratigraphic sequences, petrographic description of volcanics of maychew area geology of maychew area covered in this paper includes many lithological units (figs. 2 & 3) and the volcanic successions which reveal six cycles (referred as sequence, kabeto et al., 2004). out of six, four are related to mafic-agglomerate volcanism (exposed between 1800-2900 m a.s.l, sequences 1, 2, 3, and 4), in which basanites, and alkaline basalts and transitional ankaramites occupy the base (sequences 1, 2 and 3) followed by silica rich tholeiitic to transitional sequence 4. this is followed by sequence 5 of mafic-felsic volcanism (2900-3450 m) and that is covered by tholeiitic to transitional basalts of sequence 6 (3450-3780 m); and represent the last stage of flood basalt volcanism in the eastern part of northwestern ethiopian plateau flood basalts. the lower most mafic sequence (sequence 1) is in fault contact with cretaceous amba aradam sandstone, indicating that the base of the sequence is not exposed (figs. 2 & 3). the sequences lack major unconformities; although intercalations of 10-20 cm thick paleosols are common in some sequences otherwise volcanism and depositions were continuous (fig. 3). the lower three sequences (1, 2 & 3) are more disturbed and tilted at 4-25o towards se than upper 3 sequences (4, 5 & 6). however, along nne-ssw, nnw-sse, and ene-wsw striking normal faults they are also weakly tilted at about 3-4o, and disturbed. the altitude sub-division used above may vary depending on these normal faults throw, which is clear at bekura and tsibet mountains (figs. 2 & 3). there is evidence of deformation of the type that merla (1979) and brehe et al. (1987) used to differentiate the deformed lower and upper undeformed formations, however, such evidence was not observed in the northwestern part of the plateau (kieffer et al., 2004). in maychew area, there is a marked change in the morphology. sequence 1, 2, and 3 are marked by deformed and subdued topography. however, sequence 2 also display gently undulating kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 8 morphology and the steepness of the slope is passing from sequence 2 to 3 and the first sharp cliff marks sequence 4. the exposure of sequence 5 is marked by broken flat surface where the andesitic pyroclastics nearly eroded to flat surface (suitable agricultural land) and a resistant pediment made up of picrite and ankaramite. 2 sharp cliffs one in the middle and the other on top is marked by 15 to 10 m thick consolidated tuff and ignimbrite partly showing columnar joints. the last sequence forms tabular facies, in which flow units are about 12 m thick, alternate with braided lobes of pahoehe of ~1 to 3 m thick. the sequence 2 and 3 resemble the high-ti2 and the other sequences (4, 5, and 6) might be considered as high-tio2 1 of pik et al. (1998, 1999). however, sequence 1 is described for the first time in the ethiopian plateau geology (kabeto et al., 2004, 2006). there is systematic variation in the characteristics of the dominant volcanic rocks from the base (1800 m, mehoni plain) of the maychew volcanic sequence to the summit at the tsibet mountain (3780 m) (figs. 2 & 3) and these sequences are described below. 2.1. sequence 1: deeply weathered and often tilted basanite and basaltic agglomerate intercalations (~between 1800 and 2500 m). sequence 1 ranges in maximum thickness from 100150 m and mark the base of exposed flood basalt province (at mehoni plain and at the base of bekura mt.), and comprise many individual flows. typically occur as a series of stacked flows 26 m thick separated at places by paleosol horizons (5-20 cm). basanitic agglomerate layers are also common. the massive flows contain very few microphenocrysts (< 2%) of greenish elongated clinopyroxene (diopsidic) and fe-ti oxides with rare olivine mostly altered, in the groundmass of clinopyroxene, phlogophite, opaque, glass and rare plagioclase. 2.2. sequence 2: it ranges in thickness from 450-600 m (~ 2000-2500 m) and comprise many individual flows. it is strongly weathered and tilted. the alkaline basalt and ankaramite flows typically occur as a series of stacked flows 1-10 m thick separated commonly by patchy basaltic agglomerate (1-10 m) layers. the mafic lava flows of this sequence consist of four litho-types, ankaramite, aphanitic basalts, porphyritic basalts and basaltic agglomerates. porphyritic basalts and ankaramite predominates and often contain phenocryst (10-80%) of greenish and brownish clinopyroxene (zoned) and olivine, which are commonly iddingsitised. fe-ti oxides, plagioclase, clinopyroxene and glass form the microphenocryst and groundmass phases. few ankaramites contain abundant olivine phenocryst compared to clinopyroxene. the aphanitic flows are generally microcrystalline with few pyroxenes and altered olivine microphenocrysts and often kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 9 form the base and top of the sequence. 2.3. sequence 3: it consists of ankaramite, phyric basalts and agglomerate intercalations (~25002700 m) and ranges in thickness from 150-200 m. it comprises many individual massive cumulative ankaramites and porphyritic basalts (fig. 3). the lavas typically occur as a series of massive to blocky bodies of 30-40 m thick separated by patchy agglomerate (~2 m) and phyric basalt (2-3 m) layers. the ankaramites range in composition from pyroxene-rich at base to plagioclase-rich in the top and olivine gabbros at the middle that form intergranular/gabbroic texture consisting of dominantly ti-augite (3-6 mm), followed by plagioclase (2-3 mm), olivine and fe-ti oxides (1-2 mm), forming seriate texture. the top part of sequence 3 is plagioclase dominant basalt. 2.4. sequence 4: cliff forming aphyric to phyric basalts and basaltic agglomerate intercalations (~2700-2900 m), and has a maximum thickness of 200 m (fig. 2). the transitional to tholeiitic basaltic flows typically comprise many horizontally stratified flows of 1-5 m thick separated by patchy basaltic agglomerate (0.5-1 m). the lava flows consist of three litho-types, aphanitic, and slightly porphyritic basalts, and basaltic agglomerate. flows in this sequence typically contain up to 10% plagioclase phenocryst in a pilotaxitic groundmass of predominantly plagioclase microlites, pyroxene, and fe-ti oxides and glass now altered partly to chlorite and epidote. trachytic texture is common, and few samples contain microphenocryst of brownish clinopyroxene, fe-ti oxides, and olivine. 2.5. sequence 5: the sequence marks the bimodal volcanic activity in the northwestern ethiopian flood basalt province (~2900-3450 m). the pyroclastic rocks consist of two lithotypes: greenish to yellowish-grey andesitic tephera and grey trachy-rhyolitic ignimbrite. greenish to grey varieties form the basal part of the pyroclastic flow deposits, whereas welded variety form the top part even grading to thinly banded rhyolite (20-35 cm) flows at the top of the ignimbrite layers (fig. 2). in between the basal andesitic tephera and the top ignimbrite and rhyolite flows, phyric to aphyric basalts and picrite-ankaramite occur (fig. 2). greenish andesitic tephera variety predominates and they form crystal, rock, and glass fragments in glassy rarely devitrified and epidotized groundmass. the crystals are commonly plagioclase, aegirine-augite, and opaques possibly fe-ti oxides. in the ignimbrites, aegirine-augite and abundant sanidine with few opaque and anorthoclase, and rare rock fragments together form the fragmental part. kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 10 variably weathered and partly welded glassy ash forms the groundmass. olivine rich ankaramite show intergranular texture consists of dominantly olivine, clinopyroxene, and plagioclase. samples taken from aygi section is commonly olivine picrites, where olivine predominates over clinopyroxene and plagioclase, whereas from tsibet mountain section (figs. 2 & 3), clinopyroxene and plagioclase predominate over olivine and at places range to olivine gabbro composition similar to sequence 3 ankaramites. figure 2. schematic columnar section of maychew area (modified from kabeto et al., 2004). numbers on the left side are elevations in meter above sea level. abbreviation: sq1 = sequence1. the scale on the right of lithological column is in hundreds of meters. 2.6. sequence 6: the upper part of the flood basalt sequences in maychew area is marked by unimodal, 330 m thick transitional to tholeiitic basalt of sequence 6 (3450-3780 m), and comprise many series of horizontally stratified massive to blocky jointed 5-10 m thick lava sequence. porphyritic basalts which predominate the sequence consist of plagioclase (up to 20%) forming commonly glomeroporphyritic clots with rare clinopyroxene, olivine, and microphenocrysts of fe-ti oxides in the pilotaxitic groundmass of plagioclase, opaque, clinopyroxene, and glass. the groundmass in some thin sections is altered to chlorite. in rare kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 11 case olivine (3-5 mm) also form the dominant phenocryst phase. the petrographic study of maychew mafic lavas show systematic phenocryst assemblage variations starting from base to top, where at the base very few microphenocrysts of clinopyroxene characterizes sequence 1 (basanite). the predominance of clinopyroxene phenocryst with appearance of olivine in most samples typifies sequence 2. sequence 3 is characterized by appearance of plagioclase and predominance of clinopyroxene and olivine (ankaramite), whereas plagioclase predominate the phenocryst phase in sequence 4. olivine predominates the phenocryst phase over plagioclase and pyroxene in sequence 5; and plagioclase in sequence 6 with some variations. further, the geological traverses taken in seven different sections (fig. 2) indicate the missing of sequences from some sections. for example sequence 1 is absent in debri, tsibet, and belego sections, whereas sequence 5 is only exposed in tsibet, belego, aygi, and bolenta sections. moreover, bekura section lacks sequences 4, 5, and 6, and sequence 6 exposed on top of aygi and tsibet section (figs. 2 & 3). missing of the sequences in the area seems to be due to normal faulting and erosion. this suggests the need for detailed mapping in previously studied sections of the ethiopian plateau. figure 3. geological map of maychew area (numbers on the map indicate sequences as shown in figure 2. bora is 20 km nw and alage is 20 km north of the map area). kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 12 3. sampling strategy and analytical methods geological mapping activity and samples of all possible fresh volcanic rocks exposed within the study area were collected during three separate field seasons. seven different transects were selected within 100 km2, to enable detail mapping, and sampling a wide, a diversity of temporal and spatial chemical variations as possible in a high-ti zone of the flood basalt sequence. the samples were analyzed for whole-rock major and trace elements, and sr-, nd-, pb-, and hf isotopic data at the pheasant memorial laboratory (pml), institute for study the earth’s interior, okayama university at misasa. a total of 89 whole-rock samples were crushed using jaw crusher to coarse chips of 3-5 mm size, from which fresh chips were carefully hand-picked. they were rinsed with deionized water in an ultrasonic bath at least three times, and then they were dried at 100oc for 12 hours. the washed and dried chips were ground using an alumina puck mill. major elements, ni and cr data were obtained using x-ray fluorescence spectrometer (xrf) (phillips pw2400) on glass beads containing a lithium tetraborate flux (10 to 1 dilution of samples) (takei, 2002). loss on ignition (loi) was obtained gravimetrically. trace elements were determined by isotope dilution (id) and analyzed by inductively coupled plasma mass spectrometry (icp-ms) using a agilents 7500cs system fitted with a flow injection system (makishima & nakamura, 1997; makishima et al., 1997, 1999; yokoyama et al., 1999; moriguti et al., 2004). isotopes data for rb, sr, sm and nd were generated for the samples selected for srnd isotopic measurement, by isotope dilution thermal ionization mass spectrometry using a modified finningan mat261 instrument with nbs983 standard. trace element concentrations in caorich samples were measured by the al-addition methods as suggested by tanaka et al. (2007 & reference therein). all of the major and trace elements analyses were duplicated for each sample, and replicate analyses had <0.5 relative % and 3-5 relative % difference, for major and trace elements, respectively. the analytical procedures for chemical separation and mass spectrometry followed in the study are from yoshikawa & nakamura (1993) for sr isotope measurements; makishima & nakamura (1991) for nd; kuritani & nakamura (2002) for pb; and lu et al. (2007) for hf. to remove the effect of secondary alterations (after petrographic examinations) all powders for pband hfand some samples for sr-ndisotopic measurements were leached with 6n hcl at 70oc for about 9 hours, before acid digestions. kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 13 mass spectrometry was carried out with tims system in static multi-collection mode. normalizing factors to correct isotopic fractionation during spectrometer analysis are 86sr/88sr = 0.1194 for sr and 146nd/144nd = 0.7219 for nd. the isotopic composition of nist srm987 and lajolla standards are 87sr/86sr = 0.710190 and 143nd/144nd = 0.511863, respectively (makishima & masuda, 1993) and are reported relative to long-term (over 2 years) laboratory averages. for pb isotope measurements the correction of mass fractionation was carried out by the normal double spike method using a 207pb-204pb spike, as described by kuritani & nakamura (2003). the isotopic composition of nist srm981 pb standard gave an average (n = 5) of 206pb/204pb = 16.9424±11 (2σ), 207pb/204pb = 15.5003±12 (2σ), and 208pb/204pb = 36.7266±60 (2σ) (kuritani & nakamura, 2003). 176hf/177hf of the jmc475 and jmc14374 hf standards yield averages of 0.282150±6 (2σ, n=9) and 0.282187±8 (2σ, n=13), respectively during the course of analysis. all hf (makishima et al., 1999) isotope data for the samples are, however, reported relative to 176hf/177hf of the jmc475 = 0.282160. 4. results and discussion 4.1. classification of the volcanic flows/sequences according to the total alkali-sio2 classification diagram (fig. 4), mafic rock types range in composition from basanite, picrite-ankaramite, basalt to basalt-trachy-andesite. but transitional to sub-alkaline basalts predominate. in contrast with many continental flood basalts, the mafic rocks at maychew area do not entirely show tholeiitic affinities and also do not fall in the basalt field (fig. 4). based on the petrographic data and lithological assemblages the different mafic lavas are subdivided in to six sequences from base to top. general characteristics of the mafic rocks are illustrated in the total alkalis–silica (tas) diagram (fig. 4). the maychew sequences have compositions that plot, with some exceptions, in the alkaline and sub-alkaline field, respectively. according to the proposed classification of ethiopian flood basalts (piccerillo et al., 1979), the sequences 1 and 2 are alkaline in composition, whereas sequences 3 and 4 lavas have compositions that plot between alkaline (few) and sub-alkaline field, indicating transitional character. however, the sequence 4 shows higher sio2 contents and/or higher na2o + k2o (up to 5.2 wt.%) contents and some samples plot in the alkali field when compared to sequence 5 and 6 samples, which have lower sio2 and na2o + k2o (< 3.5 kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 14 wt.%) and plotted towards tholeiitic field line. these distinctions extend to other incompatible major and trace elements. in this study three samples from sequence 2, twelve samples from sequence 3, and five samples from sequence 5 are plotted in picrite field, having mgo contents > 12 wt.% and total alkalis < 3 wt.% (fig. 4), as per iugs classification (le bas, 2000). however, as per petrographic data these samples (picrite) since dominant in clinopyroxene, are assigned as ankaramitic picrites, whereas samples with olivine dominant as picrites. figure 4. total alkali silica classification of maychew lavas compared with the low-ti (lt) basalts (pik et al., 1998). the low-ti basalts (lt shaded, fig.4) (pik et al., 1998; kieffer et al., 2004) are compared with maychew lavas. 4.2. major element compositions of mafic rocks from the maychew flood basalt section general characteristics of the mafic rocks are illustrated in the total alkalis–silica (tas) diagram (fig. 4), and plots of the selected major and trace elements versus mgo shown in figure 5. the lavas from sequence 1 and 2 are referred as basanites because with two or three exceptions majority samples plot in the alkaline field. on the other hand, the lavas from sequences 3 and 4 are referred to as transitional ankaramite and basalt respectively as they plot in the transitional kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 15 field and from sequences 5 and 6 are referred to as tholeiitic picrites-ankaramite and basalts as they plot though within the transitional field but towards tholeiitic affinity. the maychew lava sequences can be broadly grouped from base to top as strongly alkaline, transitional, and tholeiitic and these subdivisions also well reflected in major oxides, trace element, and sr-, nd-, pb-, and hfisotopic compositional variations. the mafic lavas span a large range in mgo, from primitive (~23 wt. %) to evolved (~4 wt. %) compositions. in general, the ankaramites and picrites from sequences 3 and 5 show highest mgo content and the transitional basalts of sequence 4 the lowest. sequence 3 displays a wide variation in mgo content followed by sequences 5 and 2. sio2 content (figs. 4 & 5) for the maychew mafic lavas ranges from 42 to 54 wt. %, basanites < 45 wt.% (seq.1) and transitional basalts > 48 wt.% (seq.4). sio2, al2o3, tio2, and k2o (not shown) contents display broad negative correlations with mgo, whereas cao content in sequences 2, 3 and 5 shows initial negative correlation with mgo till the content reached 12 wt.%, afterwards the correlation becomes positive. sequences 1, 4 and 6 (if mgo rich sample is excluded) on the other hand display positive correlation compared to others indicating their differentiated nature. basanite (seq.1) shows significant compositional difference than other sequences i.e. lowest in sio2 and al2o3, highest in feototal, cao and mno (not shown) contents. further, alkaline basalt of sequence 2, also shows lower values for sio2 and al2o3 than the sequences upwards, but display higher feototal and tio2 contents. on the contrary, sequences 5 and 6 show lower values for tio2 and the highest for al2o3 with few exceptions that overlap sequences 4 and 3. k2o content is variable in most sequences, it is relatively higher in sequence 3 than sequence 4 at a given mgo content except with few overlap. similar difference can be inferred from contents of cao and tio2. major element chemical variations within each sequence can be largely explained by crystal fractionation involving olivine, clinopyroxene, iron-titanium oxides, and plagioclase, however, difference in tio2, cao, k2o, al2o3 and to some extent in sio2 and feototal among the six sequences reflect source variations or/and variable degrees of partial melting. in figure 5, major element vs. mgo, majority elements clearly show existence of compositional variations among sequences. however, in some cases there is an overlap e.g. sequence 3 and 2 overlap in more mafic compositions, but their evolved varieties differ in tio2, feototal, al2o3, and sio2 content. similarly, the sequences 3 and 4 indicate overlap in their evolved varieties in kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 16 mgo vs. al2o3, sio2, feototal and tio2, but they do differ in k2o and cao contents (fig. 5d). figure 5. mgo vs. selected major oxides for maychew lavas. lt, ht1, and ht2 and shield basalts are taken from pik et al. (1998); and kieffer et al. (2004). the notable compositional variation in sio2, al2o3, tio2, p2o5, feototal, and cao among the lavas will further demonstrate the existence of rather six sequences (1, 2, 3, 4, 5, and 6). kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 17 figure 6. mgo vs. selected trace elements for maychew lavas. the ht1 (small crossed rectangle), ht2 (shaded dots) and lt (small open circle) basalts are shown for comparison on c, e & f. ht2 overlaps fields of sequence 2 & 3, ht1 overlaps fields of evolved sequence 3, sequence 4, 5 and 6, whereas lt basalts do not overlap any of maychew sequences (when incompatible elements such as nb & la are considered). kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 18 the sequence 1 and 2 show the greatest relative enrichment in p2o5, feototal and tio5. in contrast, the upper sequences 3, 4, 5, and 6 shows relatively low p2o5, feototal, and tio2, but highly enriched in sio2 and al2o3. between 1 & 2, sequence1 shows lower sio2 (45-42 wt. %), al2o3 (12-8.5 wt.%) and tio2 (5.4-3.6 wt.%) and higher cao (15-12 wt.%) and feototal (18.216 wt.%) (figs. 4 & 5). compared to 4, sequence 3 shows higher p2o5, k2o and tio2 and lower al2o3 and cao than, however, their sio2, na2o (not shown) and feototal concentrations appear equally variable and scattered in both sequences. moreover, cao concentrations in sequence 4 lavas are higher than that of sequences 3 and 2 lavas with respect to mgo content. in the case of na2o and k2o, they are scattered considerably in all the sequences and suggest secondary redistribution of na and k. however, the extent of secondary alteration has also been evaluated using k2o/p2o5, which is > 1(not shown) in all types except for the three basanite samples from sequence 1, indicating minimum influence of subaerial weathering. k2o/p2o5 ratio is used in evaluating the effect of subaerial weathering in mafic lavas, where k is easily leached by secondary alteration and p is not. 4.3. trace element compositions of mafic rocks from the maychew flood basalt section the compatible elements ni and cr (fig. 6a & b) show perfect linear relationship with mgo and suggest the control of olivine, clinopyroxene, and cr-spinel. presence of olivine, clinopyroxene or/and cr-spinel well explains high contents of mgo, ni, and cr in picrite and ankaramite (seq. 5, 3 & 2). they are possibly mantle-derived melts having ~11% mgo (skovgaard et al., 2001). crystal fractionation is the preferred mechanism for cr depletion as its abundance is not expected to vary under conditions of increasing partial melting (pearce and norry, 1979). the incompatible elements la, nb, lu, sm, sr and rb (figs. 6c, d, e, h & f) with some scatter increase with decreasing mgo. the basanites (seq.1) at the base of maychew flood basalt section has the highest relative enrichments of incompatible trace elements (la & nb). the sequence 2, alkaline basalts and ankaramites, has intermediate contents and in the upper sequence 3, 4, 5 and 6 the trace elements sequentially depleted upwards with some scatter. basanites display relatively fractionated rare earth element (ree) patterns ((la/lu)n = 30-18 (subscript n denotes chondrite normalization) compared to other sequences (seq.2, la/lun = 169; seq. 3, la/lun = 14-7; seq. 4, la/lun = 9-6; seq. 5, la/lun = 10-6; seq. 6, la/lun = 7-5) (fig. 7d). so, there exist a good correlation of rock types with varying geochemical enrichments kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 19 such as an increase in (la/lu)n with tio2 and a general decrease in al2o3 and sio2 towards the base (figs. 6 & 7). figure 7. a). 87sr/86sr-143nd/144nd initial ratio plot, b). 87sr/86sr-143nd/144nd initial ratio plots comparing maychew lavas with volcanics in the region, c). 207pb/204pb-206pb/204pb, plot d) mgo vs la/lun plots for ethiopian flood basalt section at maychew [the data range for lt, ht1, & ht2 is from pik et al. (1999). afar group data range is from schilling et al. (1992). the red sea data is from vidal et al. (1991). arrows in c mimics way up. note: in b, dmdepleted mantle; himuhigh-µ; emenriched mantle; in c, nhrl northern-hemisphere reference-line; bk-06, ts03; and mh11a are samples which plots differently from the sequence. 4.4. isotope variations among the analyzed isotopes, sr-nd isotope data (fig. 7 a & b) when plotted, two clusters are formed, one with restricted and low sr (0.70356-0.70345) and nd (0.51290-0.51284) isotopic compositions, defined by sequence 1 samples, and the other cluster with relatively higher sr kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 20 igure 8. a). εhf-εnd, b). εhf vs 208pb/204pb initial, c). 208pb/204pb vs 206pb/204pb, and d). 208pb/204pb vs ce/pb plots for maychew flood basalt samples. c1, c2, c3, and c4 in b, indicate mixing components defined by the maychew lava sequence. the three afar plume mantle end components further elucidated in figure 8c where sequence 1 and 0 ma afar group 2 (schilling et al., 1992) displaced towards the highest 206pb/204pb ratios. in figure 8d most samples are plotted within and above the proposed mantle range, however, some samples are (lower part of sequence 3 and upper part of sequence 4 & 5) are displaced towards c4, crustal component. symbols for maychew lavas are as in figures 4 & 7. (0.7052-0.7036) and nd (0.51296-0.5127), defined by sequence 2. other sequences show more scattered patterns. f kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 21 b isotopic compositions (figs. 7c & 8) also show a systematic variation from base to top, with equence 1 having the most radiogenic signature (206pb/204pb = 19.10-19.30, 207pb/204pb = 15.605.65) while sequence 4 indicating lower values (206pb/204pb = 18.20-18.56, 207pb/204pb = 15.515.55). sequences 2 and 3 lavas display similar 206pb/204pb and 207pb/204pb ratios. sequence 6 amples on the other hand though show lower 207pb/204pb (fig. 7c) values, they are higher 06pb/204pb than in the samples from sequences 2, 3, 4 and 5. similarly lavas of sequence 1 and 4 re relatively less radiogenic 176hf/177hf than sequence 2 (fig. 8a). in other sequences the data how slight scattered pattern (fig. 7c). these variations are quite different from what has reviously been reported for northwestern ethiopian flood basalt province (pik et al., 1999). . conclusion • the ht1+ht2 zone of northwestern ethiopian flood basalt province show sequential compositional variations (seq 1-seq 6). the sequence 2 & 3 are similar to ht2 of pik et al (1998), whereas sequence 4 overlaps the ranges of ht1 basalts of pik et al (1998). • • geochemical variations in lavas are interpreted to reflect mixing of three mantle components, with minimal crustal in-put as a fourth component. o m the second enriched com flood basalt, p s 1 1 s 2 a s p 5 sequence 1, basanites is described for first time in this study and enriched in incompatible elements more than the ht2 basalts. sequence 5 and 6 show different chemical variations in isotopic ratios than ht1 and ht2. smooth increase of (la/lu)n ratios down the sequence reflect the general decrease of degree of partial melting of heterogeneous packages of mantle materials. the systematic • the enriched sequence 1 has very similar geochemistry to himu-type ocean island basalts, and this ascribed as end member t the ost enriched afar plume component 1 involved in the initial continental break-up. • the second enriched component is defined on the basis of the geochemistry of the samples from sequences 2 & 3 which reflect ponent in ethiopian previously described (pik et al., 1999) as high-ti2 basalts assumed to be the afar plume component. • the third component would be the depleted one as defined by samples from sequence 4, kurkura, k (mejs) volume 2 (1): 4-25, 2010 © cncs mekelle university 22 al., 1999). e between the 1st and 2nd enriched afar plume components might be due to • 6. ack ku r (jsps) ry in japan’ to ise o editor d 7. ref ayalew gu, g & pik. r. 2002. source, genesis, and berhe, of the cenozoic magmatic province in w and se ethiopia. j. coulie` tive k–ar and ar/ar dating of ethiopianand yemenite oligocene volcanism: hofmann, c., courtillot, v., feraud, g., rochette, p., yirgu, g., ketefo, e & pik, r. 1997. ones, p. 1976. age of the lower flood basalts of the ethiopian plateau. nature, 261: 567–569. which partly overlaps the range previously reported for low-ti basalts (fig. 8; pik et • the differenc variable lithospheric signatures, with the 2nd enriched afar plume component having more lithospheric material. the forth component is crustal signature (fig. 8d) which invariably affected all the lava sequences. crustal signatures are quite prominent in sequences 3 & 4 compared to others. nowledgements rku a kabeto acknowledges financial support from japanese society for promotion of science and also by the program for the ‘center of excellence for the 21st centu i, kayama university. i thank prof. talat ahmad and dr. k. bheemalingeswara, and the r. tadesse for their constructive comments on the manuscript. erences d., barrey, p., marty, b., reisberg, l., yir timing of giant ignimbrite deposits associated with ethiopian continental flood basalts. geochemica et cosmochimica acta, 66: 1429-1448. s.m., desta, b., nicoletti, m & tefera, m. 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digestion. chemical geology, 157: 175-187. kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 screening some tef [eragrostis tef (zucc.)trotter] accessions/varieties for salt tolerance during germination and seedling stage *kinfemichael geressu asfaw1 and fisseha itanna2 1department of biology, college of natural and computational sciences, mekelle university, p.o. box 231, mekelle, ethiopia (*kinfe_michael2006@yahoo.com) 2 department of biology, addis ababa university, p.o. box 1176, addis ababa, ethiopia (fissehai@yahoo.com) abstract salinity is a continuing problem in the arid and semi-arid tracts of the world. it could be alleviated using irrigation management and/or crop management. however, the former approach is outdated and very expensive. nevertheless, the latter is economical as well as efficient, and it enables to produce salt tolerant crop lines. but prior to that there is a need to confirm the presence of genetic based variation for salt tolerance among different species or varieties of a particular crop that can thrive under unreliable agro-ecological situations; tef [eragrostis tef (zucc) trotter] is one of such crops. thus fifteen lowland tef genotypes (10 accessions and 5 varieties) were tested during germination and seedling stage at 2ds/m, 4ds/m, 8ds/m, 12ds/m and 16ds/m salinity levels. distilled water (0ds/m) was used as a control. data analysis was carried out using sas package. germination percentage (gp), germination rate (gr), seedling shoot length (ssl) and seedling root length (srl) were measured. the analyzed data showed significant variation among most parameters recorded for accessions and varieties (p < 0.01) and for treatments (p < 0.001). germination rate and seedling root length were more salt affected than final germination percentage and seedling shoot length respectively. the main cause for reduced and delayed germination percentage was osmotic effect. the ion effect was also learned to be minimal. most accessions and varieties failed to germinate at 12ds/m and 16ds/m salinity levels. thus, these salt concentrations were not important in screening tef genotypes for salt tolerance. varieties such as dz-01-1281, dz-cr-358 and accession 236512 were found to be salt sensitive. however, variety dz-cr-37 and accessions 237186, 237131 and 212928 were found to be salt tolerant. the rest accessions and varieties were intermediate in their salt tolerance. the study affirmed the presence of broad intraspecific variation among tef accessions and varieties for salt tolerance but more in the former. key words: accessions, germination, nacl, salinity, eragrostis tef. 1. introduction salt-affected soils are found throughout the world. that is why brandy and weil (2002) claimed that no continent is free from the problem. salt-affected soils are serious threats to crop production in the arid and semi-arid tracts of the world (verma and yadava, 1986). globally, a total land area of 831 million hectares is salt-affected. african countries like kenya (8.2mha), nigeria (5.6mha), sudan (4.8mha), tunisia (1.8mha), © cncs mekelle university kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 tanzania (1.7mha) and ghana (0.79mha) are salt-affected to various degrees (fao, 2000). in ethiopia, salt-affected soils are prevalent in the rift valley and the lowlands. the awash valley in general and the lower plains in particular are dominated by salt-affected soils (tadele gebresellassie, 1993). for example, soil salinity has caused a significant abandonment of banana plantation and showed a dramatic spread to the adjacent cotton plantation of melka sadi farm (fentaw abegaz, 1995). studies by hailay tsige et al. (2000) also indicates that of the entire abaya state farm, 30% has already been saltaffected. this problem is expected to be severe in the years to come. this is because under the prevailing situation of the country, there is a tendency to introduce and implement large-scale irrigation agriculture so as to meet the demands of the everincreasing human population by elevating productivity (tekalign mamo et al., 1996). in the absence of efficient ways of irrigated water management, salt build up is an inevitable problem. the possible solution is either using physical practice (irrigation frequency and leaching, irrigation methods, cyclic use of multi-quality waters, fertility management and amendments) or biological practice (attainment of salt tolerant species and cultivating through biological approaches) (gupta and minhas, 1993). since physical practice (irrigation management) is not economically feasible, according to el-khashab et al., (1997), there is a need to concentrate on the biological approach or crop management (ashraf and mcneilly, 1988). nevertheless, to proceed with this approach, affirming the presence of genetic based variation for salt tolerance in a particular crop is a requisite (marler and mickelbart, 1993). thus in doing so, one has to focus on crops that have been cultivated for a long period of time in a country, and are able to provide reliable yield under unreliable agro-climatic conditions and make ranking first against area coverage, demand and market value. tef [eragrostis tef (zucc) trotter] is one of such crops, which has been cultivated in the country as a cereal crop for quite long (purseglove, 1972). furthermore, tef can be adapted to a broader range of agro-climatic environments. it can grow in altitudes ranging from sea level to 2800m.a.s.l, under different moisture, soil, temperature and rainfall regimes. it can tolerate anoxic situations better than maize, wheat and sorghum. it has © cncs mekelle university 18 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 ease of storage, tolerance to weevils and other pests.the straw is preferred to any other cereal straws and can fetch premium price (seyfu, 1993). according to mengesha et al.(1965), it contains higher amount of a number of minerals than wheat, barley or grain sorghum. as compared to other cereals, the largest cultivated land area is covered by tef. moreover, the area used for tef production is increasing from time to time (hailu and seyfu, 2000). for example, it covered 1,818, 375 (in 2001/02) and 1,989,068 (2003/04) hectares of land which is 28.5 and 28.4 percent of the area covered respectively by the whole cereals in each production year (csa, 2004). generally, tef is a reliable cereal an under unreliable climate. that is why, in many areas where recurrent moisture stress occurs, tef production replaces the production of maize and sorghum (seyfu ketema, 1993). therefore, this article attempted to screen 15 genotypes (10 accessions and 5 varieties) of tef [eragrostis tef (zucc.)trotter] in the germination and seedling stage. 2. materials and methods seeds of 10 tef accessions were obtained from the institute of biodiversity conservation (ibc) whereas 5 tef varieties were supplied by debre zeit agricultural research center (dzarc), ethiopia. the specific tef genotypes used in the research were accessions 55017, 205217, 212611, 212928, 229747, 231217, 236512, 236514, 237131, 237186, and varieties dz-cr-358, dz-01-196, dz-01-1281, dz-01-168 and dz-cr-37. the accessions were adapted to altitude ranging from 1150 – 1550 meters a.s.l. where as the varieties were adapted to altitudes from 1400 – 2400 meters a.s.l. germination experiment was conducted from december 14, 2003 to january 24,2004 at melkassa agricultural research centre (marc) using a 1996 model fitotron plant growth chamber where 75% relative humidity, 200c temperature, 114 µmolm-2sec-1 incandescent and florescent light and 12 hours day/night duration were maintained (azhar and mcneilly,1987). the experiment assessed the germination response of tef genotypes to different nacl salinity levels. the nacl concentrations used were 2ds/m, 4ds/m, 8ds/m, 12ds/m and 16ds/m; distilled water (0ds/m) was used as a control. these salinity levels were obtained by dissolving 1.17g, 2.34g, 4.68g, 7.02g and 9.36g nacl in one litre distilled water respectively. glass petri dishes with a diameter of 10cm were © cncs mekelle university 19 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 lined with whatman no.3 filter paper and were arranged in a randomized complete block design (rcbd) with four replications. each petri dish was supplied with 5ml of the respective treatment solution. in such a way 20 tef seeds were planted. treatment application was made continued every other day and germination count was started after 72 hours of sowing and continued until the 13th day. a seed was considered to have germinated when both the plumule and the radicle emerged > 0.5cm. after 13 days, overall shoot and the longest root length of ten randomly selected seedlings from each replicate were measured using a draftsman ruler (azhar and mcneilly, 1987). germination rate (gr): the average number of days needed for plumule or radicle emergence was calculated as (lemma desalegne, 1996): nt3 + nt6+ nt9+ nt12 germination rate (gr) = total number of seeds germinated where: tn = number of seeds germinated at day 3, 6, 9, 12 n = days (3, 6, 9, 12) similarly, seedling shoot-to-root ratio (srr) was calculated as the ratio of seedling shoot length (ssl) to seedling root length (srl). 3. statistical analysis data analysis was carried out by sas package where two ways analysis of variance (anova) and correlation analysis were employed. prior to data analysis, shoot-to-root ratio (srr) was log transformed. at 12ds/m and 16ds/m, almost all accessions and varieties collapsed after germination. consequently, the incomplete data obtained from these salinity levels had been excluded from the data analysis of germination rate (gr), seedling shoot length (ssl), seedling root length (srl) and shoot-to-root ratio (srr). 4. results 4.1. final germination percentage (fgp) the analysis of variance (anova) showed significant variation for accessions and varieties (p < 0.001) and treatments (p < 0.001). genotype * treatment interaction effect was also found to be significant (p < 0.001). except variety dz-cr-358 all genotypes © cncs mekelle university 20 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 (both accessions and varieties) achieved more than 85% final germination percentage at 2ds/m. moreover, this salt concentration stimulated seed germination in variety dz-011681. at 4ds/m, all accessions and varieties attained more than 75% final germination percentage (fgp) except accession 236514 (56%) and variety dz-01-1281 (32.5%). at 8ds/m, varieties like dz-01-1281(5%) and dz-cr-358 (10%) and accessions 236514 (30%), 236512 (25%) and 231217 (35%) achieved only from 5 to 35% final germination percentage (fgp). however, the rest accessions and varieties attained from 40 to 91.3% final germination percentage (fgp). at 12ds/m, tef genotypes germinated from 7.5% to 83.8% but variety dz-01-1281 failed to germinate. on the other hand, at 16ds/m the final germination percentage reduced from 50 to 98.7% and accession 231217 and variety dz-01-1281 failed to germinate. 0 20 40 60 80 100 120 r o n k m s c e d t a h g y p accessions/varietie s f in al g er m in at io n p er ce n ta g e ( f g p ) 0ds/m 2ds/m 4ds/m 8ds/m 12ds/m 16ds/m figure 1. effects of different salinity levels (0, 2, 4, 8, 12 and 16ds/m) on final germination percentage (fgp) of tef [eragrostis tef (zucc.)trotter] accessions and varieties. (key to accessions: a = 231217, c = 212611, e = 229747, g = 236514, h = 236512, m = 55017, n = 237186, o = 237131, r = 212928 and s = 205217; key to varieties: d = dz-01-196, k = dz-cr-37, p = dz-01-1281, t = dz-01-168 and y = dzcr-358). every salinity level resulted in reduced germination percentage in most accessions and varieties. nevertheless, the drop was sharp and rapid in accessions like 236512, 232117 © cncs mekelle university 21 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 and 236514 as well as in varieties such as dz-cr-358 and dz-01-1281 at 8ds/m, 12ds/m and 16ds/m salinity levels (fig. 1). 4.2. germination rate (gr) the analysis of variance (anova) for germination rate (gr) showed significant variation among accessions (p < 0.001) and treatments (p < 0.001). every salt treatment delayed the emergence of plumule and radicle compared to the control. however, the influence became pronounced with higher salt concentrations (fig.2). from the entire genotypes considered, accessions 231217 and 236514, and varieties dz-01-1281 and dz-cr-358 were the most salt-affected as compared to the control. however, accessions 212928, 237131, 237186 and variety dz-cr-37 were the least salt-affected genotypes. 0 2 4 6 8 10 12 14 r o n k m s c e d t a h g y p acce ssion/varie ty g er m in at io n r at e (g r ) 0ds/m 2ds/m 4ds/m 8ds/m figure 2. effects of different salinity levels (0, 2, 4 and 8ds/m) on germination rate (gr) of tef [eragrostis tef (zucc.)trotter.] accessions and varieties. (key to accessions: a = 231217, c = 212611, e = 229747, g = 236514, h = 236512, m = 55017, n = 237186, o = 237131, r = 212928 and s = 205217; key to varieties: d = dz-01-196, k = dz-cr-37, p = dz-01-1281, t = dz-01-168 and y = dz-cr-358). 4.3. average seedling shoot length (ssl) the analysis of variance (anova) revealed significant variation among accessions (p < 0.001) and treatments (p < 0.001) for average seedling shoot length (ssl). © cncs mekelle university 22 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 genotype*treatment interaction effect was also significant (p < 0.01) reflecting all the accessions and varieties responding differently to salt stress with respect to average seedling shoot length (ssl). increased salinity levels resulted in a decreased average seedling shoot length (ssl) in accessions 231217, 236512 and 236514 and varieties dzcr-358 and dz-01-1281. nevertheless, average seedling shoot length (ssl), brought about no influence in accessions 212928, 237131 and 237286 and varieties dz-01-196, dz-01-1681 and dz-cr-37 by salt stress up to 8ds/m. 4.4. average seedling root length (srl) the analysis of variance (anova) confirmed the presence of significant variation in average seedling root length (srl) among genotypes (p < 0.001) and treatments (p < 0.001). lower salt concentrations caused stimulated seedling root length (srl). for example, average seedling root length (srl) was stimulated at 2ds/m in accessions 205217, 237131 and 237186 and at both 2ds/m and 4ds/m in variety dz-cr-37. nevertheless, higher salt concentrations resulted in a reduced average seedling root length (srl). at 8ds/m a reduction of 72.7, 73, 75, 87.5 and 88.9 percent was observed in accessions 236514, 236512, 231217 and varieties dz-01-1281 and dz-cr-358 respectively as compared to the control. on the other hand, average seedling root length (srl) of accession 237186 and 212928, variety dz-cr-37, accession 237131 and variety dz-01-1681 decreased by 31.9, 38.6, 44.7, and 48.8 percent respectively at 8ds/m salinity level as compared to the control. 4.5. seedling shoot-to-root ratio (srr) the analysis of variance (anova) for seedling shoot-to-root length ratio (srr) depicted significant variations for accessions/varieties (p < 0.001) and treatments (p < 0.001). genotype* treatment interaction effect was also learned to be significant (p < 0.001). this reflects that accessions and varieties responded to salt stress differently with respect to seedling shoot-to-root ratio (srr). as the salinity level increased, srr showed increment compared to the controlled part. this was quite pronounced in accessions 229747 (80%), 231217 (70.77%), 236512 (70%) and 236514 (64.47%) as well as in varieties dz-cr-358 (81.88%) and dz-01-1281 (81.54%) (fig.3). nevertheless, in accessions 212928 (40.63%) and 237186 (35.14%) the increment in srr as a result of higher salt concentration (8ds/m) was minimal. © cncs mekelle university 23 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 m s c r e a h g o n y d p t k accession/variety s ho ot -to -r oo t r at io ( s r r ) 0ds/m 2ds/m 4ds/m 8ds/m figure 3. effects of different salinity levels (0, 2, 4 and 8ds/m) on seedling shoot-toroot length ratio (srr) of tef [eragrostis tef (zucc.)trotter.] accessions and varieties. key to accessions: a = 231217, c = 212611, e = 229747, g = 236514, h = 236512, m = 55017, n = 237186, o = 237131, r = 212928 and s = 205217; key to varieties: d = dz01-196, k = dz-cr-37, p = dz-01-1281, t = dz-01-168 and y = dz-cr-358). 4.6. correlation analysis the correlation analysis showed a positive and significant correlation between average seedling shoot length (ssl) and average seedling root length (srl), and between germination rate (gr) and seedling shoot-to-root ratio (srr) (p<0.001). furthermore, final germination percentage (fgp) was significantly and positively correlated with both average seedling shoot length (ssl) and average seedling root length (srl). on the other hand, average seedling root length (srl) and final germination percentage (fgp) depicted a negative and significant correlation with seedling shoot-to-root ratio (srr) and germination rate (gr) (p<0.001). 5. discussion the positive significant correlation between ssl and srl as well as between gr and srr indicates that tef genotypes responded to salt stress more or less in a similar manner © cncs mekelle university 24 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 with respect to these parameters. the negative significant correlation between gr and srl might imply that the extended exposure of a particular genotype to salt stress could cause the entrance of excessive na+ and clinto the cells (dudeck et al., 1983). this might disturb membrane integrity owing to the replacement of ca2+ by na+ (suhayda et al., 1992) and in turn, it might lead to further entrance of na+ and out flow of important ions such as k+ (ashraf and waheed, 1993). on the other hand, the insignificant negative correlation between ssl and gr reflects that there was no excessive entrance of na+ into shoot cells. so, the average seedling root length (ssl) was more salt-affected than the average seedling shoot length (ssl). this is evident from the significant negative correlation between srl and srr as well as from the increment of srr in response to increased salt concentration. final germination percentage (fgp) was reduced by every salt treatment in most genotypes. likewise, similar results were reported in triticale (norlyn and epstein, 1983), oats (verma and yadava, 1986), rice (lee et al., 1998), durum wheat and tef (tekalign mamo et al., 1996). every salt treatment has delayed germination rate the effect being more pronounced with higher salt concentrations. this is in agreement with reports in intermediate wheat grass (hunt, 1965), spring wheat (ashraf and mcneilly, 1988), pearl millet (singh et al., 1999), perennial rye grass (horst and dunning, 1989), and sorghum (marambe and ando, 1995). moreover, the delay was remarkable in sensitive and intermediate accessions as compared to the tolerant genotypes. germination rate was more salt-affected than final germination percentage, which is consistent with previous report in triticale (francois et al., 1988). crop genotype may germinate effectively under salt stress; nevertheless, its seedling growth will be affected (azhar and mcneilly, 1987). contrary to this, accessions 237186, 237131 and variety dz-cr-37 that were the most salt tolerant genotypes in terms of final germination percentage (fgp) and germination rate (gr) showed promising seedling growth. it has already been reported that plant growth and development is dependent on crop stand establishment (verma and yadava, 1986), in turn the latter is a function of effective germination (horst and taylor, 1983) and seedling growth (ashraf and wheed, 1992). crops with higher germination percentage and low germination rate can establish themselves effectively on moderately saline soils (with 2ds/m – 10ds/m electrical © cncs mekelle university 25 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 conductivity) (lee et al., 1998). thus, even if it is difficult to extrapolate the research result obtained from controlled laboratory experiment directly to the field, the above genotypes have salt tolerance which enables them to germinate and establish on moderately saline areas. consequently, this would help to minimize grain yield loss that could emanate from inadequate crop stand establishment as a result of poor germination and seedling growth. thus these genotypes have agricultural significance for the entire world in general and for the country in particular. contrary to gorham and hardys’ (1990) generalizations that tef is salt sensitive and unable to regulate the influx of salt ions such as na+ and cleven at very low salinity levels; variety dz-cr-37 and accessions 212928 and 237186 were able to attain more than 75% final germination percentage (fgp) at 12ds/m. in contrast to previous report in soybean (abel and mckenzie, 1964), a broad intraspecific variation among tef accessions and varieties was obtained with the variations more pronounced in the former. therefore, this would allow more salt tolerant lines to be selected from the existing tef germplasm. salinity is a growing problem worldwide. thus to alleviate the existing and the upcoming problems, there should to be similar and profound studies on tef and other crops. 6. acknowlegements the authors are grateful to rpsud (research programme for sustainable use of dryland biodiversity) for financial assistance and marc ( melkassa agricultural research center) for equipment and laboratory provision. moreover, we are indebted to ibc (institute of biodiversity conservation) and dzarc (debre zeit agricultural research center) for supplying tef [eragrostis tef (zucc.) trotter] accessions and varieties respectively. furthermore, we thank professor tekalign mamo and mr. sintayehu hundie for their constructive advice and comments. 7. reference abel, h. g & mackenize j. a. 1964. salt tolerance of soybean varieties (glycine max l.) during germination and later growth. crop science, 4(2):1053-1056. © cncs mekelle university 26 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 azhar, m. f & mcneilly, t. 1987. variability for salt tolerance in sorghumn bicolor (l.) moench under hydroponic conditions. j. agronomy and crop science, 159: 269277. ashraf, m & mcneilly, t. 1988. variability in salt tolerance of nine spring wheat cultivars. j. agronomy and crop science, 160:14-21. ashraf, m & waheed, a. 1992. screening chickpea (cicer arietinum l.) for salt tolerance. j. agriculture in the tropics and subtropics, 93:45-55. ashraf, m & waheed, a. 1993. resposes of some local/exotic accessions of lentil (lens culinaris medic.) to salt stress. j. agronomy and crop science, 170:103-112. brady n c & weil, r. r. 2002. the nature and properties of soils. 13th edition. prentice-hall, upper saddle rivers, new jersey. central statistical authority. 2004. agricultural sample survey 2003/2004, volume i. report on area and production of crops (private peasant holdings, meher season). statistical bulletin 302, addis ababa, 127 pp. dudeck, a.e, singh, s., giordano, c.e., neel, t. a & mcconnell, d.b. 1983. effects of sodium chloride on cynodon turfgrasses. j. agronomy, 75 (6):927-930. el-khashab, a. a.m., elaidy, a.a., el-sammak, a. f., salama, m.i & rienger, m.1997. paclobutrazol reduces some negative effects of salt stress in peach. j. amer. soc. hort. science, 122(1):43-46. fao/agl. [online] available http://www.fao.orglag/agl/agll/spush/ topic? htm; november, 2000. fentaw abegaz, 1995. effects of subsurface drainage system on ground water table, soil salinity and crop yield in melka sadi pilot drainage scheme. in: woldeyesus sinebo, zerihun tadele and nigusie alemayehu (eds.), increasing food production through improved crop management. proceedings of the first and inaugural conference of the agronomy and crop physiology of ethiopia, 30-31 may 1995, iar, addis ababa, ethiopia,139-148 pp. francois, e. l., donovan, t. j., maas, e. v & rubenthaler, l. g. 1988. effects of salinity on grain yield and quality, vegetative growth, and germination of triticale. j. agronomy, 80(4):642-647. © cncs mekelle university 27 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 gorham, j & hardy, a. c. 1990. response of eragrostis tef to salinity and acute water shortage. j. plant physiology, 135(6):641-645. gupta, r & minhas p s. 1993. managing salt affected waters for crop production. in: s.d. singh (ed.), arid land irrigation and ecological management. scientific publishers, new delhi, 159-198 pp. hailay tsige, tadele g/sellasie & tekalign mamo. 2000. assessment of salinity/ sodicity problems in abaya state farm, southern rift valley of ethiopia. ethiopian journal of natural resources, 2(2):151-163. hailu tefera & seyfu ketema. 2000. production and improvement of tef in ethiopian agriculture. in: hailu tefera, getachew belay and m.sorrells (eds.), narrowing the rift: tef research and development. proceedings of the international workshop on tef genetics and improvement, 16-19 october 2000, addis ababa, ethiopia. horst, g. l & dunning, n. b. 1989. germination and seedling growth of perennial ryegrasses in soluble salts. j. amer. soc. hort. sci., 114(2):338-342. horst, g.l & taylor, r.m. 1983. germination and initial growth of kentucky blue grass in soluble salts. j. agronomy, 75(4):679-681. hunt, o. j. 1965. salt tolerance in intermediate wheatgrass. crop sci., 5(5):407-409. lee, k. s., choi, y. s & choi, y. w. 1998. varietal difference in salinity tolerance during germination stage of rice. korean j. crop science, 43 (1):11-14. lemma desalegne. 1996. salt tolerance in tomatoes (lycopersicon esculentum hill). a thesis submitted by lemma deslegne for the degree of doctor of philosophy. department of agricultural botany, school of plant science, university of reading, 245 pp. marambe, b & ando, t. 1995. physiological basis of salinity tolerance of sorghum seeds during germination. j. agronomy and crop science, 174:291-296. marler, t. e & mickelbart, m. v. 1993. growth and chlorophyll fluorescence of spondias purpurea l. as influenced by salinity. tropical agriculture (trinidad), 70(3) : 245-247. © cncs mekelle university 28 kinfemichael and fisseha (mejs) volume 1 (2):17-29, 2009 mengesha haile melak, pickett, c. r & davis, l. r. 1965. genetic variability and interrelationship of characters in tef, eragrostis tef (zucc.) trotter. crop science, 5(1): 155-157. norlyn, d. j & epstein, e. 1983. variability in salt tolerance of four triticale lines at ggermination and emergence. crop science, 24:1090:1092. purseglove, j. w. 1972. tropical crops: monocotyledons. longman group limited london. 607 pp. seyfu ketema. 1993. tef [eragrosits tef), breeding, agronomy, genetic resources, utilization and role in ethiopian agriculture. institute of agricultural research, 102 pp. singh, j. n., sharma, d. k & chillar, r. k. 1999. forage yield and chemical composition of pearl millet (pennisetum typhodes) as influenced by exchangeable sodium. j. agric. sci. camb., 111(3):465-467. suhayda, c. g., redmann, r.e., harvey, b. l & cipywnyk, a. l. 1992. comparative response of cultivated and wild barely species to salinity stress and calcium supply. crop science, 32(1):154-163. tadelle gebresellassie, 1993. degradation problems of irrigated agriculture: in: soil-the resource base for survival. proceedings of the second conference of esss, 2324 september 1993, addis ababa., ethiopia, 199-206 pp. tekalign mamo, richter, c & heiligatag b. 1996. response of some varieties of durum wheat and tef to salt stress. j. african crop sciences, 4(4):423-432. verma, s. p. o & yadava, r. b. r. 1986. salt tolerance of some oats (avena sativa l.) varieties at germination and seedling stage. j. agronomy and crop science, 156:123-127. © cncs mekelle university 29 hydrogeological investigation and groundwater potential assessment in haromaya watershed, eastern ethiopia nata tadesse1*, bheemalingeswara1, k and abdulaziz2, m 1department of earth science, college of natural and computational sciences, mekelle university, mekelle, ethiopia (*tafesse24603@yahoo.com) 2harari national regional state agricultural and rural development bureau, harar, ethiopia abstract the paper assesses groundwater quality and productivity in haromaya watershed, eastern ethiopia. continuous pumping test data, collected from seven boreholes was used to determine productivity of the aquifers. 14 water samples were tested for water quality. the aquifers on the basis of permeability, potential and extent of aquifers, are categorized into i) extended and shallow aquifers with intergranular porosity and permeability, and with moderate to high potential (alluvial and lacustrine sediments); ii) limited and shallow aquifers with fracture and/or karstic porosity and permeability, and with moderate potential (sandstone and limestone); and iii) limited and shallow aquifers with intergranular and fracture porosity and permeability, and with low potential (granite). on the basis of chemical data, the water is fresh except in lacustrine and swampy areas. hco3-, ca2+, na+ and mg2+ are the dominating ions in water from granite, sandstone and alluvium; and cl and so4 dominate in water from lacustrine sediments apart from hco3-, ca2+, na+ and mg2+. areas suitable for groundwater development in the area are discussed. keywords: aquifer, ethiopia, groundwater potential, haromaya, hydrogeochemistry. 1. introduction the study area, haromaya watershed in eastern ethiopia, is currently serving as a source of groundwater supply for the three major towns: harar, alemaya, awaday and haromaya university main campus, besides the rural areas where the farmers are also extracting groundwater for different purposes. sixteen functional boreholes and more than 160 hand-dug wells are found drilled in the watershed. in principle, the development of groundwater in an area should be preceded by an investigation of the groundwater resources. continued development thereafter will increase the importance of the groundwater as contributor for the socio-economic development of the area. however, this is not the case in the study area. besides in the area there is no regulation for the abstraction of water from these wells. also there is no predetermined prioritisation between different water uses and water users. all these practices expose the groundwater resources of the area to mismanagement and risk. © cncs mekelle university nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 1.1 description of the study area the study area, haromaya watershed, is located in oromiya regional state, eastern part of ethiopia, about 505 km east of addis ababa. geographically, the study area is bounded between latitudes 42° 05' 16'' n and 43° 55' 12'' n; and longitudes 9° 21' 40'' e and 9° 27' 13'' e with areal extent of about 50.3 sq. km (fig. 1). the area is located in the harerghe plateau in the southeastern highlands and lowlands physiographic unit of the country. the harerghe highlands lying in the eastern part of the country are generally known for their rugged topography, mountainous landscapes which govern the variations in regional geomorphology, soil sequences, ecological zones, quantity and quality of plant and animal life (tamire h., 1981). steep to very steep slopes, hilly and mountainous area, which covers 18% of the total area of the watershed, characterize the eastern and northeastern parts of the watershed. flat to gentle slopes, which cover 82% of the total area of the watershed and has a slope ranging 0-15%, characterize the remaining parts of the watershed. this physiographic unit includes a swampy area that lies in the southwestern part of the watershed. the slope of the watershed rises slowly in all directions away from the swampy area. the slope, landform and the configuration of the hills and peaks surrounding the study area have created a drainage network, which takes the surface flow towards the swampy area. the major streams are: lega-hidha, lega-ambo, lega-burqa and lega-bati and all the flows are intermittent. these streams are supplied by gullies, ephemeral streams, road channels and sometimes directly from overland flows of adjacent farmlands. the drainage pattern of the area is sparse dendritic type. the monthly air temperature of the watershed range from 3.8°c at december to 25.2°c in march, and the mean annual is 16.7°c (nata et al., 2006). the highest value of the minimum temperature is 13.6°c and the lowest value of the minimum temperature is 3.8°c, whereas the highest and lowest values of maximum mean temperatures are 25.20c and 22.5°c, respectively. the minimum mean and maximum mean temperatures are 9.6°c and 23.8°c, respectively. present research work was proposed to conduct hydrogeological investigation and assess groundwater potential of the haromaya watershed with following objectives. • identification of the major water bearing formations; • characterization of different aquifers; • determination of aquifer productivity: transmissivity and hydraulic conductivity; and ©cncs mekelle university 27 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 • determination of chemical-type and quality of water. figure 1. location map of the haromaya watershed. 2. methodology the methods used in this study include literature review, field investigation, laboratory analysis and data analysis using different software. aerial photographs and topographic maps at a scale of 1:50,000 (karsa and harar: with reference numbers 0941 d2 and 0942 c1, respectively) were studied carefully. the aerial photographs were used to identify the geological structures and trace them on to the topographic sheet of 1:50,000 scale. the topographic sheet was used as base map in the field to mark the lithologies, their contacts and trends and to develop detailed geological and hydrogeological maps of the area. primary geological and hydrogeolgical data were collected in the field after having the secondary data. hydrogeological field investigation was concentrated more on differentiating the rock units ©cncs mekelle university 28 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 of groundwater significance (such as the degree of fracturing of the rock units, the extent of weathering, the type and degree of cementation, the thickness of the formations, the grain size, shape and sorting, and the clay proportion) and in collecting hydrogeological information, i.e., locating of water points, collection of water samples, and measurement of discharge of wells. for determining the productivity of the aquifers within the study area continuous pumping test data from seven boreholes drilled in unconsolidated aquifer were used. in the watershed, due to the unavailability of the piezometer and recovery data, the analyses have been performed only for constant rate pumping test by using the pumping borehole data. the drawdown data of all boreholes have been analyzed using neuman method (neuman, 1975; cited in krešić, 1997): drawdown versus time. analyses of all data have been carried out using aquifertest software. the program contains analytical solutions for pumping and slug tests for confined, unconfined, and leaky confined aquifers. the classification of the aquifer productivity was carried according to sen (1995) based on transmissivity values. for hydrogeochemical investigation, 14 water samples (4 springs, 7 hand dug wells, and 3 boreholes) were collected for laboratory analyses. in-situ measurements of electrical conductivity (ec), temperature, ph, and total dissolved solids (tds) were made. the water samples were collected into properly cleaned and labeled one liter plastic bottles. the samples were again tested for ec, ph, temperature and tds in the laboratory to cross check the data. all the water samples were analyzed for major cations (ca+2, mg+2, na+, k+, total iron, mn+2, nh4+,) and anions (hco3-, cl-, so4-2, co3-2, f-, no2-, no3-, po4-3) in the water works design and supervision enterprise laboratory service, addis ababa. interpretation of all water chemistry data have been carried out using aquachem software. aquachem is a fully-integrated software package developed specifically for graphical and numerical analyses and interpretation of aqueous geochemical data sets. piper diagram was used for representing and comparing water quality analyses in the watershed. 3. geology the geology of the watershed is constituted by the rocks ranging in age from precambrian to recent. stratigraphically, from bottom to top, they are granite (precambrian), sandstone and limestone (mesozoic sedimentary rocks) and recent sediments (quaternary) (fig. 2). detailed description of these units is given below. ©cncs mekelle university 29 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 igure 2. geologic map of the haromaya watershed. .1 granite his rock forms part of the precambrian stratigraphy of ethiopian geology. it is an intrusive luton present within the basement gneissic rocks. it is mainly exposed in the north, ortheastern, eastern, southeastern, southern and central parts of the watershed. this unit covers bout 46.3% of the total area of watershed. the granite (batholith) rock is massive and shows ght pink color. it is characterized by well developed medium grained quartz and orthoclase rystals. it is cut across and intersected by a number of quartz veins having thickness of about 3 10 centimeters and with predominantly north-south orientation. the length of the veins ranges rom few cm to 1.5 m. granite, with the exception of the northern ridges, is highly weathered in ther parts of the watershed and shows light gray color. maximum thickness of the weathered ranite is about 25 m which is found in a river cut exposure in western parts of the watershed. .2 sandstone ed consist of two formations, the sandstone nd limestone. both together cover about 19.4 % of the total area of the watershed. sandstone pping in the eastern, northeastern, northwestern, western, and southwestern parts of f 3 t p n a li c to f o g 3 the mesozoic sedimentary successions of the watersh a unit is outcro ©cncs mekelle university 30 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 the watershed and overlie the basement granite, and occupies 14.3% of the mapped area. it shows yellowish to pink color and predominantly consists of fine to medium grained quartz. the rock shows well sorted, rounded grains, cross bedding and red color on the surface due to weathering. it is non-calcareous except at the top near the contact with the overlying limestone, where thin beds of limestone have developed. in the southwestern part, reddish brown massive mudstone intercalations are found in sandstone varying in thickness from 20 cm to 1 m. average thickness of the sandstone unit ranges from 20 to 200 m, and shows well developed vertical joints (nata et al., 2006). generally the sandstone is highly weathered and fractured, and found forming hills and ridges in the area. in all parts where it is exposed, it is found covered with shallow soil. the age of the sandstone is triassic (garland, 1972). 3.3 limestone the outcrops of this unit are present in the northeastern part of the watershed. it overlies the sandstone unit and cover about 5.1% of the mapped area having a maximum thickness of about 180 m (nata et al., 2006). the limestone is fossiliferous and micritic having very fine grained calcite crystals. it shows intercalations of thin beds of light brownish color marl varying in thickness from 3 to 5 m. it shows gray and light yellowish to black colors due to weathering. at places the unit is highly weathered and shows well developed karst topography. the rock occupies high elevations in the topography and forms steep cliffs in the area. this unit is regionally correlated with the upper hamanlei formation of the ogaden basin and the antalo formation of northern ethiopia, which is considered to be upper jurassic (mohr, 1963). 3.4 alluvial deposits the alluvial deposits are mainly found in the central part of the watershed as thin strips along the margins of the major rivers and their tributaries. these sediments constitute about 16.7% of the total area and show e-w alignment. they stretch from the eastern and northeastern parts from mountain to the swampy area. the relative abundance and stratigraphic relation the bottom of the of the sediments, however, are generally not uniform throughout the area. towards the mountain front, which is in the northeastern and eastern parts of the watershed, where steep topographic slopes exist and the gradient of the rivers is high, the alluvial sediments, in general, are dominated by sub-angular to sub-rounded coarse grained fragments with variable content of coarse grained sand. in the central parts of the watershed, where the gradient of the rivers ©cncs mekelle university 31 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 decreases down slope, the dominant alluvial deposit is medium to fine grained sand with variable content of silt and clay. 3.5 lacustrine deposits the lake sediments are found occupying the dried haromaya lake and also in the current shallow aquifers with intergranular porosity and permeability diments: alluvial and lacustrine sediments); .1.2 aquifer characteristics oirs are mainly controlled by the type of geology, degree ring or geological structures, and geomorphology of the area. in this section haracteristics of the different rocks and unconsolidated sediments of the onsolidated sediments the lacustri r water flowing from the nea the ma tributaries are the most common shallow aquifers which swampy area of the watershed. it covers about 17.7% of the total area. compositionally the deposits are comprised of clay and silt in different proportions. the sediments are characterized by well developed hexagonal cracks having an opening space ranging from 1 to 5 cm. 4. results and discussions 4.1 hydrogeology 4.1.1 aquifer types different rocks and unconsolidated sediments in the study area which behave as aquifers have been classified on the basis of permeability which they exhibit and the extent of the aquifer. they are: 1. extended and (unconsolidated se 2. limited and shallow aquifers with fracture and/or karstic porosity and permeability (sandstone and limestone); and 3. limited and shallow aquifers with intergranular and fractured porosity and permeability (granite). 4 groundwater occurrence and its reserv of geological weathe the hydrogeological c watershed have been discussed with particular reference to their water storage and transmission capacities. 4.1.2.1 unc recent sediments, which cover about 34.4% of the total mapped area in the form of ne and alluvium serve as one of the major storage volumes fo rby highlands. alluvial deposits in the central part of the watershed and as thin strips along rgins of the major rivers and their ©cncs mekelle university 32 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 can place to place depending on their grain size, sorting and thickness. lacustrine sediments on the grained with clay, and their thickness range from 3 to 18 m, most be tapped by large diameter hand dug wells. their permeability and productivity vary from other hand are dominantly fine being between 10 to 18 m (fig. 3). being rich in clay, the sediments have a very low permeability and productivity and serve as confining or semi-confining layers. the poor drainage characteristics of these sediments lead to water logging. figure 3. borehole log of the haromaya watershed (after abdulaziz and nata, 2006 ). 4.1.2.2 sandstone in the watershed there is no borehole that was drilled and found in this unit. however, five hand dug wells are found drilled on it. the assessment of permeability and productivity of the sandstone was carried out based on field observation and limited lithological logs due to lack of pumping test data from boreholes in the watershed. accordingly, the sandstone has moderate permeability and productivity. its moderate permeability and productivity is resulting from the limited shale intercalation, bedding planes and the deep vertical jointing. infiltration and recharge occur mainly through these joints and bedding planes. its lack of high degree of permeability and productivity is due to the varying medium to fine grain size and degree of ©cncs mekelle university 33 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 cementation. generally, in the sandstone, intergranular permeabilities are low but secondary in the watershed, in most places sandstone form hills and ridges. these landforms act as runoff imited infiltration can take place along fractures and joints, these landforms planes. however, the degree of gs characteristically emerge at the contact of the limestone with rvation. accordingly, this unit as a whole may be taken or productivity. this degree of productivity is associated mainly with the porosities and permeabilities due to fracturing are significant. s zones. even though l make the exploitation of groundwater resource of the formation quite limited because the groundwater availability in these types of landforms, in general, is very poor. however, a large number of high discharge springs characteristically emerge at the contact of the sandstone with the underlying basement rock. outside the watershed in the nearby area, the permeability and productivity of the sandstone were evaluated based on pumping test data of boreholes. accordingly, the sandstone has a moderate permeability and productivity. 4.1.2.3 limestone in the watershed, the limestone has appreciable secondary porosity and permeability as a result of fractures, solution structures and openings along bedding permeability and productivity of this formation is highly controlled by the landforms that it constitutes. the rock forms steep mountains and cliffs. these landforms act as runoff zones. even though limited infiltration can take place along fractures and joints, these landforms make the exploitability of groundwater resource of the formation quite limited because the groundwater availability in these types of landforms in general is very poor. however, a few number of high discharge sprin the underlying sandstone. in the watershed there is no hand dug wells and boreholes that were drilled and found in this unit. due to this, the assessment of the productivity of this unit as a whole was carried out based on field obse as an aquifer of po topography that it constitutes and to a lesser degree to the nature of the intercalated thin beds of marl. 4.1.2.4 granite the granite occurs as crosscutting intrusive bodies in the north, northeastern, eastern, southeastern, southern and central parts of the watershed, and is found covering 46.3% of the total area of watershed, having a maximum thickness of more than 100 m in the southeastern parts. the granite forms round shaped bodies and is affected by strong exfoliation due to the ©cncs mekelle university 34 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 weathering processes. however, the weathering processes affected only the shallow upper parts of the rock. following are the important features of granite which enhances its usefulness to the water supply: ● occurrence of weathering zone; ● occurrence of tectonic fractures; ● contact with the surrounding metamorphic rocks; and ● wide differences in composition, structure and texture and corresponding variability hydraulic parameters of the same rock. wells ranges from 0.7 to 3 l/s. most of the hand dug wells are dried within 15 minutes watering pump of 5 l/s discharge, indicating the low producti t of the productivity of the weathered layers and fractured imited lithological logs due to lack of p and fractur w permeability and productivity. this of the in the watershed there is no borehole that was drilled and found in this unit. however, more than ten hand dug wells are found in it. the weathered layers and fractures are the main sources of groundwater supply in granitic rock of the watershed. as a result, the extent of weathering and fracture characteristics decide its hydraulic conductivity and other properties. in all the hand dug wells the main aquifer is found to be weathered and fractured granite. the depth of the hand dug wells range from 3.7 to 25.0 m. the static water level ranges from 3 to 19 m. the discharge of the hand dug when they were discharged with de vity nature of the rock. assessmen zones was carried out based on field observation and l umping test data from boreholes in the watershed. accordingly, the weathered layers ed zones as a whole are estimated to have lo degree of permeability and productivity is due to the presence of medium to coarse grain sized particles and absence of secondary minerals in the weathered layers and limited infiltration that can take place along the fractures and joints. their lack of moderate and high degree of productivity is mainly due to the limited thickness of fractured zones and weathered layers, the presence of fine grained materials both in the weathered layers and the overlying alluvium and the landforms which they form. 4.2 aquifer productivity 4.2.1 hydraulic characteristics of unconsolidated sediment aquifers all the boreholes (20 boreholes) and 158 of hand dug wells are found drilled in the sediments. out of the twenty boreholes, four are abandoned and the rest are functional. the depths of the boreholes range from 13 to 66 m and the yields vary from 2 to 15 l/s. the depths of static water ©cncs mekelle university 35 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 level also vary from 2.2 to 14.0 m. among the boreholes and hand dug wells in the sediments of the watershed, only the performance of 16 boreholes have been checked by pumping test. however, pumping test data are available only for the seven boreholes of hare town water supply and sewerage authority. pumping test and recovery test data were not obtained for the other nine boreholes and for all the 158 hand dug wells, and quantitative estimates of the performance of these boreholes and hand dug wells have not been determined. the following is the result of the analyses of the pumping test data obtained from the seven boreholes. 1 borehole was drilled at elevation of 2018 m above seal level with a nducted for 72 hours at a nutes. the m was measured. according to the neuman drawdown the harer emergency well total depth of 47 m. the static water level is 2.2 m. the pumping test was co constant rate of 10.30 l/s. after a continuous 72 hours pumping, a volume of 2669.76 m3 water was pumped out and a drawdown of 10.3 m was measured. according to the neuman drawdown versus time method (fig. 4), a transmissivity of 5.23 x 10-4 m2/s and a hydraulic conductivity of 2.17 x 10-5 m/s have been computed. the harer emergency well 2 borehole was drilled at elevation of 2023 m above sea level with a total depth of 65 m. the static water level is 13.9 m. the pumping test was conducted for 24 hours at a constant rate of 4.46 l/s. after a continuous 24 hours pumping, a volume of 285.344 m3 water was pumped out and a drawdown of 4 m was measured. in this borehole the recovery was fast. according to harer town water supply and sewerage authority (2003) cited in abdulaziz and nata, 2006) report, the borehole recovered 92% of the total drawdown within 5 mi computed transmissivity and hydraulic conductivity values, by the neuman drawdown versus time method (fig. 5), are 1.4 x 10-3 m2/s and 5.2 x 10-5 m/s, respectively. the harer emergency well 3 borehole was drilled at elevation of 2015 m above sea level with a total depth of 39 m. the static water level is 3.78 m. the pumping test was conducted for 10 hours at a constant rate of 10 l/s. after a continuous 10 hours pumping, a volume of 360 m3 water was pumped out and a drawdown of 10.63 versus time method (fig. 6), a transmissivity of 5.2 x 10-4 m2/s and a hydraulic conductivity of 2.88 x 10-5 m/s have been computed. the harer emergency well 4 borehole was drilled at elevation of 2013 m above sea level with a total depth of 52.3 m. the static water level is 3.95 m. the pumping test was conducted for 21 hours at a constant rate of 18 l/s. after a continuous 21 hours pumping, a volume of 1360.8 m3 water was pumped out and a drawdown of 9.3m was measured. according to the neuman drawdown ©cncs mekelle university 36 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 versus time method (fig. 7), a transmissivity of 5.62 x 10-4 m2/s and a hydraulic conductivity of 3.11 x 10-5 m/s have been computed. figure 5. neuman plot of drawdown versus time at the pumping borehole well 2. figure 4. neuman plot of drawdown versus time at the pumping borehole well 1. igure 6. neuman plot of drawdown versus time at the pumping borehole well 3. f ©cncs mekelle university 37 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 figure 7. neuman plot of drawdown versus time at the pumping borehole well 4. igure 8. neuman plot of drawdown versus time at the pumping borehole well 5. figure 9. neuman plot of drawdown versus time at the pumping borehole well 6. f ©cncs mekelle university 38 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 figure 10. neuman plot of drawdown versus time at the pumping borehole well 7. the harer emergency well 5 borehole was drilled at elevation of 2014 m above sea level with a total depth of 53 m. the static water level is 2.89 m. the constant rate pumping test was conducted for 48 hours at discharge rate of 18 l/s. after a continuous 48 hours pumping, a volume of 3110.4 m3 water was pumped out and a drawdown of 8.91 m was measured. according to the neuman drawdown versus time method (fig. 8), a transmissivity of 5.78x10-4 m2/s and a hydraulic conductivity of 2.4 x 10-5 m/s have been computed. the harer emergency well 6 borehole was drilled at elevation of 2011m above seal level with a total depth of 44m. the static water level is 4.86m. the constant rate pumping test was conducted for 37 hours at a constant discharge of 16 l/s. after a continuous 37 hours pumping, a volume of 2131.2 m water was pumped out and a drawdown of 11.76m was measured. a3 ccording to the neuman drawdown versus time method (fig. 9), a transmissivity of 5.3 x 10-4 m2/s and a hydraulic conductivity of 1.6 x 10-5 m/s have been computed. the harer emergency well 7 borehole was drilled at elevation of 2020 m above sea level with a total depth of 44 m. the static water level is 5.65 m. the constant rate pumping test was conducted for 41 hours at an average discharge rate of 22 l/s. after a continuous 41 hours pumping, a volume of 3247.2 m3 water was pumped out and a drawdown of 13.72 m was measured. according to the neuman drawdown versus time method (fig. 10), a transmissivity of 6.83 x 104 m2/s and a hydraulic conductivity of 2.62 x 10-5 m/s have been computed. enerally, according to sen (1995) classification, the aquifer potential of unconsolidated ediment aquifers ranges from moderate to high. g s ©cncs mekelle university 39 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 watershed. figure 11. hydrogeological map of the haromaya ©cncs mekelle university 40 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 4.3 hydrogeochemistry he results of the geochemical analyses are shown in the tables 1 and 2 and in figures 12 15, nd are discussed below. .3.1 granite ive groundwater samples were analyzed from the granitic rock terrains of the watershed show lightly alkaline character. they are fresh (tds less than 1000 mg/l), neutral to slightly basic nd very hard (figs. 12a & 13a). alkalinity of the groundwater ranges from 193.8 to 354.9 mg/l aco3. except in one, other samples show above 300 mg/l caco3 alkalinity values (fig. 13a). n terms of temperature the groundwater samples show variation from 19.7ºc to 25.8ºc. among e anions, hco-3 is dominant over cland so42-. the measured bicarbonate (hco-3) oncentrations range from 236.4 mg/l to 433.0 mg/l (table.2; fig.14a). the anions cland so42 ccur in only minor concentrations. the highest measured chloride concentration is 46.6 mg/l nd the lowest is 12.4 mg/l. the highest measured sulfate concentration is 49.4 mg/l and the west is 17.33 mg/l. the bicarbonate concentration in granitic rock can be accounted for by the issociation of water under the presence of carbon dioxide. the prevailing ph (6.8 8.5) table.1) is also one of the factors for the existence of the bicarbonate as major dissolved organic constituents in the groundwater. over most of the normal ph range of groundwater (6 ), bicarbonate is the dominant carbonate species. the anions cland so42are not significant onstituents in silicate rocks. since their occurrence is normally be attributed to atmospheric ources, to the decomposition of organic matter in soil, and to the trace impurities in rocks and inerals, there is no such condition exists in granite. any possible increase of so42and clis lso restricted because of limited movement of groundwater. mong cations, alkaline earths elements are relatively higher in concentration (ca2+ and mg2+) ompared to alkalis (na+ and k+) (table.2; fig 14b). without exception, ca2+ is dominant over g2+. there is a dominance of na+ over k+, as sodium is more soluble than potassium, and the tter is generally more easily fixed on clay minerals in the rock matrix. hence k+ is the least bundant among cations. chemical character of water varies from ca hco3, ca na hco3, nd ca mg hco3 types (fig.15). though bicarbonate and alkaline earth elements are xpected to be contributed from the rock but slightly higher amounts of na compared to k is t a 4 f s a c i th c o a lo d ( in 9 c s m a a c m la a a e contributed from the overlying sediments. ©cncs mekelle university 41 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 figure 12. ph of the groundwater samples in (a) granite; (b) in sediment. figure 13. tds, alkalinity and total hardness for groundwater (a) granite; (b) sediment. figure 14. variation in anion (a) and cation (b) concentrations in water (note: water sample no. 1=hw alluvial; 2-4 = hw granite; 5-8=hw lacustrine; 9-10=sp sandstone; 11-12=sp granite; 13-15=sp alluvial). ©cncs mekelle university 42 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 figure 15. piper diagram of hydrochemical data in the haromaya watershed. the fluoride content which ranges from trace to 0.5 mg/l (table.2) is generally contributed from nce of inor amounts of biotite is expected to be the source for fluoride in the present case. among secondary and minor constituents or trace elements total iron and manganese, both show very low concentrations below 0.5 mg/l (table.2). these concentrations are low because of constraints imposed on the solubility of iron and manganese –bearing minerals or forming hydrous oxides of iron and manganese in the soil environment. nitrite and ammonia concentrations in water samples are insignificant compared to the other nitrate nitrogen species. in all the analyzed samples the concentrations of nitrite is nil, but nitrate concentrations range from 7 to 21.5 mg/l. the most abundant nutrient in water from all the samples is nitrogen in the form of nitrate. unlike most other elements in groundwater, nitrate is not derived primarily from origina the fluoride-bearing minerals like apatite, fluorite and biotite in the rocks. possible prese m the minerals in rocks that make up the groundwater reservoir. nitrate in groundwater generally tes from nitrate sources on the land surface, in the soil zone, or in shallow subsoil zones ©cncs mekelle university 43 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 where nitrogen-rich wastes are buried. natural nitrate concentrations in groundwater range from .1 to 10 mg/l (davis and dewiest, 1966). as shown in table 2, only in one hand dug well, the itrate conc itrate occurs at oncentrations well above 10 mg/l. here the presence of nitrate is mostly attributed to the open it latrines as there are no proper sewerage systems in the watershed. ammonia concentrations re also very low ranging from 0.15 to 0.25 mg/l and generally contributed from anthropogenic r the overlying organic rich sediments. hosphate (po43-) values are ranging from 0.041 to 0.123 mg/l. in general phosphate oncentration of groundwater in granitic rock terrains of the watershed is low, due to the resence of high concentration of calcium. the phosphate may be due to the presence of hosphorus-bearing minerals like hydroxylapatite (ca5(oh)(po4)3), strengite (fepo4.2h2o) and arisite (alpo4.2h2o) in the rocks. the dominant control on phosphorus in the groundwater one is the solubility of these slightly soluble phosphate minerals. .3.2 sandstone he chemistry of spring water in sandstone is slightly alkaline, fresh and very hard (tables. &2). ca2+ is dominant among cations and hco3among anions (fig.14 a&b). alkalinity values nges from 310.1 to 326.4 mg/l caco3 (table. 1) and temperature from 18.5 ºc to 24.5 ºc. in e sandstone aquifer the major ions in the groundwater calcium and bicarbonate assumed to be very low in water. imilarly, among anions, chloride and sulfate are also found in very small concentration. 0 n entration is below 5 mg/l. in the remaining four samples n c p a o p c p p v z 4 t 1 ra th from calcite dissolution. other cations magnesium, sodium and potassium are s chemical type of water is mainly ca mg hco3 type (fig.15). the measured fluoride concentrations are below 0.5 mg/l. natural concentrations of fin groundwater mainly depends on the availability of fin the rocks or minerals encountered by the water during its transport and on solubility constraints imposed on fluorite (caf2) or fluorapatite (ca5f(po4)3). the fact that nearly all groundwaters are undersaturated with respect to fluorite and fluorapatite suggests that the fcontent of groundwater is generally limited due to nonavailability of fin the rocks and sediments through which the groundwater moves rather than by the solubility these minerals (freeze and cherry, 1979). other anions like nitrite and ammonia show very low concentrations. though, nitrite values are almost nil, the highest concentration recorded for ammonia is 0.188 mg/l. on the other hand, the highest measured nitrate concentration is 19.5 mg/l. this amount of concentration is mostly ©cncs mekelle university 44 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 attributed to the open pit latrines as there are no proper sewerage systems in the watershed. the phosphate (po43-) concentrations are also insignificant. as shown in the table 2, among trace elements, both total iron and manganese show very low concentrations and insignificant. 4.3.3 sediments eight groundwater and spring water samples analysed from the sediments of the watershed indicate that they are slightly alkaline, fresh (except hw9), neutral ph and very hard (table.1; figs. 12b and 13b). in the case of the sample hw9, the water is brackish in character. alkalinity values ranges from 148.9 to 446.8 mg/l caco3. temperature values are ranging from 20.1 ºc to 24 ºc. ca2+ is the dominant cation, followed by sodium (na+), magnesium (mg2+) and potassium s a second abundant anion in nd hw-10 and clin sample hw-7. in the case of sample hw-9, clis the – mg hco3 and ca – na meters like phosphate (po43-), mn and fe (total) are insignificant in the groundwater from both the alluvial and lacustrine aquifers. (k+) ions in both the groundwater of the alluvial and lacustrine aquifers (fig.14b). hco3is the dominant anion and clthe second most abundant anion followed by so42in the groundwater from alluvial aquifer (fig.14a). here, the anions cland so42occur in only minor concentrations. however, in the groundwater from lacustrine aquifers hco3-, cland so42ions show variation in concentration in all the samples. with the exception of sample hw9, in all other samples hco3is the dominant anion followed by so42a samples hw-8 a dominant anion and so42the second most abundant anion followed by hco3-. water samples from lacustrine sediments in general show high concentrations for the anions cland so42-. this high concentration of cland so42in the groundwater is mostly attributed to the dissolution of chloride and sulfate from lacustrine marl and evaporites, which can contribute salinity to the groundwater in this aquifer system. fluoride concentrations are less than 1.2 mg/l in water from both the alluvial and lacustrine aquifers. the highest measured fluoride concentration is 1.1 mg/l. chemical types of groundwater from the alluvial aquifer are ca hco3 types; and from the lacustrine sediment are ca – na hco3 – cl, ca – mg – na hco3 – so4, na – ca – mg – cl – so4 and na ca – mg hco3 – so4 types (fig.15). nitrite and ammonia concentrations in groundwater from both alluvial and lacustrine aquifers are insignificant. though groundwater is free from nitrite, it indicates presence of nitrate whose concentration is around 17.5 mg/l. in the case of ammonia, the highest value recorded is 0.65 mg/l. nitrate concentration is mostly attributed to the open pit latrines as there are no proper sewerage systems in the watershed. other analysed para ©cncs mekelle university 45 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 5. conclusion • as part of hydrogeological investigation different types of aquifers are noted and demarcated. • on the basis of the relationship between hydraulic properties and geology in the area, the aquifer rocks have been classified in to low, medium and high potential for groundwater. • among different aquifers, the one associated with unconsolidated sediments have to high potential; followed by the sandstone having moderate potential and h 3 moderate granite with low potential; and limestone characterized by weak and poor potential aquifers. • hydrogeochemical data indicate that the water in general is fresh except the water in lacustrine sediments and swampy areas as indicated by ec and tds. • hydrogen ion concentrations though vary between 7 and 8; neutral values are observed in water from granite and sandstone; and slightly basic in lacustrine and swampy areas. bicarbonate values that are closely related to ph though broadly follow the same trend show variations in the rocks and sediment. • high concentrations of sulphate and chloride in lacustrine and swampy areas thoug are assumed to be due to increased residence time and they do not show any relation with hydrogen ion concentration. • among cations ca2+ and among anions hco3are the dominating ions. • nitrate, ammonia and fluoride though low concentration, nitrate may increase with time from anthropogenic sources. iron and manganese as expected are very low in concentration. • water from the rocks and sediment clearly indicate variation in their chemical character. hco3-, ca2+, na+ and mg2+ are the dominating ions in water from granite, sandstone; and cl and so4 dominate in water from lacustrine sediments apart from hco -, ca2+, na+ and mg2+. • any future development of groundwater should be concentrated on the moderate to high degree potential aquifers. • further investigations are to be done to establish lateral extent and vertical thickness of the moderate to high degree potential aquifers; and to know the presence of additional multilayer aquifers, their respective thickness and productivity. ©cncs mekelle university 46 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 6. acknowledgments the hare town water supply and sewerage authority is duly acknowledged for funding this research project and also providing the necessary data. thanks are also due to all those friends he field and laboratory work and for going through the manuscript many tim 7. r f abdula davis, freeze, garland 72. explanation of the geological map of adigrat sheet (nd 37-7), 1:250,000 krešić, r modeling, lewis mohr, nata, t . 2006. water balance of haromaya basin, şen, z. tamire forest conditions in hararghe high lands, alemaya. who helped during t es and providing many constructive comments. e erences ziz, m & nata, t. 2006. optimum groundwater utilization and management in lake alemaya watershed, eastern ethiopia. mekelle university, mekelle, ethiopia. s.n & dewiest, r.j.m. 1966. hydrogeology. john wiley and sons, new york, 463 pp. r.a & cherry, i.a. 1979. groundwater, prentice hall, inc., new jersey. , c.r. 19 scale. ethiopian institutes of geological survey (e.i.g.s.), addis ababa. n. 1997. quantitative solutions in hydrogeology and groundwate publishers, boca raton. p.a. 1963. geological map of the horn africa, 1:2,000,000 scale. philip and jacey, london. ., dubey, n., mintesnot, k & shami, m oromiya, eastern ethiopia. b.sc thesis, mekelle university, mekelle, ethiopia. 1995. applied hydrogeology, crc press, boca raton. , h. 1981. soil, water and unpublished report, alemaya university, alemaya, ethiopia. ©cncs mekelle university 47 nata, t., bheemalingeswara, k and abdulaziz, m (mejs) volume 2 (1): 26-48, 2010 ©cncs mekelle university 48 table 1. location and som nt p eter the ae importa aram s of nalyzed water samples. sample id easting (m) northing (m) ec td alk (mg/l ness ater -bearing ation ( altitude m) ph (µs/cm) s (mg/l) alinit caco y (3) total hard mg/l caco3) w type f water orm hw-1 176750 104 -mg-3171 2101 7.62 664 408 324.4 384.1 ca hco3 alluvial hw-3 175571 104 -hc1113 2051 7.27 693 414 342.7 371 ca o3 granite hw-4 828104 104 708 -hc0460 2043 7.34 474 228.5 325.5 ca o3 granite hw-5 828272 104 528 -na-1936 2031 7.68 336 193.8 238.7 ca hco3 granite hw-7 170767 104 793 ca-na-1348 2018 7.54 500 255 345 hco3-cl lacustrine hw-8 172611 104 966 ca-mg-0355 2014 7.65 648 354.96 427.5 na-hco3-so4 lacustrine hw-9 171799 104 292 na-ca-0751 2011 7.38 0 1890 291.7 868 mg-cl-so4 lacustrine hw-10 173319 104 48 na-ca-2855 2020 7.68 4 318 148.9 151.9 mg-hco3-so4 lacustrine sp-1 178675 104 62 ca-mgands4507 2203 7.09 8 404 310.1 332.01 hco3 s tone sp-2 178049 104 66 41 ca-mgands4093 2181 7.15 9 8 326.4 349.4 hco3 s tone sp-4 177517 104 78 49 ca-mgranit3059 2113 7.06 0 4 346.8 386.3 hco3 g e sp-6 178840 104 73 44 ca-mgranit2810 2126 7 6 8 354.9 438.3 hco3 g e bh-0 174135 104 80 49 ca-mglluvi1428 2028 7.66 4 4 352.9 412.3 hco3 a al bh-1 173975 104 70 44 ca-nalluvi1732 2028 7.36 2 4 269.3 256.1 hco3 a al bh-7 173925 104 103 63 ca-mglluvi2432 2028 7.35 3 2 446.8 509.9 hco3 a al g ples. table 2. anion and cation concentrations (m /l) in groundwater and spring water sam hw-1 hw-3 7 h sp-4 sp-6 -1 hw-4 hw-5 hwhw-8 w-9 hw-10 sp-1 sp-2 bh-0 bh bh-7 na+ 11.7 19 1 10.7 6.5 61 32 28 5 70 290 52 6.3 7.3 31 51 k+ 1.4 1 2 8 1.3 .4 4.6 1.8 1.3 2.3 2.6 0.6 0.8 1.4 2 1.7 ca+2 91.4 121.8 7 .8 1 101.8 122. .6 106.1 8.3 108 96.6 82.7 35.7 93.1 91.35 7 126.2 76 152.3 mg+2 35.3 15.2 .7 29.9 29.9 .7 13.7 9.8 16 42.14 93.1 14.2 22.54 27.44 22.1 14 29.4 fe tot 0.03 trace tra e tr trace trace e trace ce trac trace ace 0.02 trace trace trace trac trace mn+2 trace trace t tra 5 trace trace 02 tracerace ce 0.0 0.02 0.05 trace trace trace trace 0. f 0.15 0.5 tra .5 0.15 trace 96 0.40.45 ce 0 0.8 0.5 1.1 trace 0.5 trace 0. 5 cl 14.3 19.95 2 .7 46 19 12.4 .1 46.6 8.5 63 42.8 1.7 35.2 9.5 8.6 31.4 37 57 no3 12.5 7 1 2 5 14.3 14.2 10 4.25 1.5 5 17.5 8.5 19.5 19.5 5 8 8 co3 -2 trace trace trace e tracetrace trace trace trace trace trace trace trace trace trace trac hco3 395.7 418.1 2 23 .1 3 35 37 423.1 43 .5 5478.7 6.4 311 43 5.9 181.7 8.3 398.2 3 430.6 328 5 so4 -2 11.28 17.33 19 6 3 46 1 .95 17.3 .5 24.49.5 .3 6 151. 7.5 71.5 1.5 11 26 3 24.75 71 7 po4 -3 0.08 0.103 0. 0.062 1 0 0. 0.0 0.062 0.041 08 0.06123 0.04 0.08 .041 0.062 041 62 0.246 0. 2 nh4 + 0.275 0.15 0.25 2 0 0.1 0.188 0.4 13 0.0.15 0.2 0.26 0.65 0.39 .13 88 0.15 0. 65 participatory technology and constraints assessment to improve the livelihood of beekeepers in tigray region, northern ethiopia gidey yirga* and mekonen teferi biology department, college of natural and computational sciences, p.o. box 3072, mekelle university mekelle ethiopia (*gidey1998ec@yahoo.com) abstract beekeeping is a long-standing practice in the rural communities of ethiopia and appears as ancient history of the country. a three–part assessment and diagnostic study (livelihood systems assessment, integrated honeybee management needs assessment and diagnostic survey) was undertaken from 2006-2008 in tigray, ethiopia to identify market and technological constraints facing the honey sub sector and asses bee pests and the control measures taken. information was gathered through pra, interview with key informants and integrated honeybee management diagnostic survey in the rural areas. the assessment and diagnostic activities were undertaken in six zones (western, north western, central, eastern, southern and southeastern zones of the region). one hundred nineteen beekeepers were randomly selected. information on the adoption of new technology, availability of honeybee pests, average annual harvest of honey, honeybee pest controlling measures, market and technological constraints etc. were sought from the beekeepers. honey yield was markedly different for the traditional and modern hives. on average, it was about 8-15 kg/hive and 20-30 kg/hive from the traditional and modern hives respectively. lack of adequate bee forages, poor market, lack of trained development agents, inadequate government support, bee pests and inadequate training are mainly the problems facing the honey sub sector in the region. there are different kinds of bee pests and predators. honey is harvested twice a year. from this study it was realized that almost all beekeeping practices are traditional except little intervention with improved beekeeping practices. key words: beekeeping, bee management, beehive, tigray. 1. introduction beekeeping is a long-standing practice in the rural communities of ethiopia and appears as an ancient history of the country (ayalew and gezahegn, 1991). beekeeping is an environmentally friendly and non-farm business activity that has immense contribution to the economies of the society and to a national economy as whole. ethiopia has a huge natural resource base for honey production and other hive products, and beekeeping is traditionally a well established household activity in almost all parts of the country. however, the benefit from the sub sector to the nation as well as to the farmers, traders, processors and exporter is not satisfactory (beyene and david, 2007). beekeeping as a business is a resent development in ethiopia. presently, honey is highly commercialized and its market surplus accounts for over 90 per cent of the total harvest. the © cncs mekelle university gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 large portion (70 per cent) of the marketed honey goes to the production of tej (beverage) and only around 30 per cent is used as a table honey. moreover, the volume of export in both honey and beeswax products has notably declined since the last decade. this is largely attributed to the deterioration in quality of the products, eu (european union) restriction and increasing demand in the domestic market (beyene and david, 2007). the total honey production of ethiopia is estimated up to 24000 metric tones; only a small amount of this is marketed. besides poor marketing conditions the main reason is that about 80 per cent of the total ethiopian honey production goes in to the local tej-preparation, a honey wine, which consumed as national drink in large quantities (hartmann, 2004). in ethiopia, beekeeping is a promising non-farm activity for the rural households. it contributes to the incomes of households and the economy of the nation. the direct contribution of beekeeping includes the value of the outputs produced such as honey, bee wax, queen and bee colonies, and other products such as pollen, royal jelly, bee venom, and propolis in cosmetics and medicine (arsd, 2000 and gezahegn, 2001). it also provides an employment opportunity in the sector. the exact number of people engaged in the honey sub-sector in ethiopia is not well known. however, it is estimated that around one million farm households are involved in beekeeping business using the traditional, intermediate and modern hives. it could also be observed that a large number of people (intermediaries and traders) participate in honey collection and retailing (at village, district and zonal levels). thousands of households are engaged in tej-making in almost all urban areas, hundreds of processors are emerging and exporters are also flourishing (beyene and david, 2007). honey and beeswax also play a big role in the cultural and religious life of the people of ethiopia. another very important contribution of beekeeping is through plant pollination and conservation of the natural environment. beekeeping is environmentally sustainable activity that can be integrated with agricultural practices like crop production, animal husbandry, horticultural crops and conservation of natural resources. thus, it would be one of the most important intervention areas for sustainable development of poor countries like ethiopia (gibbon, 2001). the contributions of beekeeping in poverty reduction, sustainable development and conservation of natural resources have been well recognized and emphasized by the government of ethiopia and non-governmental organizations (ngos). as the country is endowed with varied ecological zones and different flora, it has a huge potential for beekeeping. however, the roles of © cncs mekelle university 77 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 beekeeping as income generation or diversification for subsistence farmers and generating foreign exchange earnings have been very minimal. plentiful forage availability coupled with favourable and diversified agro-climatic conditions of ethiopia create environmental conditions conducive for the growth of over 7000 species of flowering plants which has supported the existence of large number of local bee colonies in ethiopia. it is estimated that over two million bee-colonies in the countries exists in the forest and crevices. the density of hives occupied by the honeybees on the land may be the highest, at the present moment, of any country in the african continent (ayalew and gezahegn, 1991). ethiopia's wide climatic and edaphic variability have endowed this country with diverse and unique flowering plants, thus making it highly suitable for sustaining a large number of bee colonies and the long established practice of beekeeping. nevertheless, the bees and the plants they depend on, like all renewable natural resources, are constantly under threat from lack of knowledge and appreciation of these endowments (girma, 1998). in general, the potential areas for honey and beeswax production in the country include southwestern, western and north-western parts of the country (arsd, 2000 and gezahegn, 2001). these are grouped into high, medium and low potential areas. many of the districts in tigray, wollo and hararege and in some other parts of the country which are covered with marginal forests do have relatively low potential in honey production (beyene and david, 2007). the principal resource base for beekeeping has, however, become seriously degraded in the course of time. the potential of the ethiopian landscape for honey and wax production does now, undoubtedly, only constitute a small fraction of its former wealth. moreover, the destruction of the remaining resource-base can be observed going on at a steadily accelerating pace (girma, 1998). based on the level of technological advancement three types of beehives are used for honey production in ethiopia. these are traditional, intermediate, and modern hives. a total of about 4,601,806 hives exist in the country of which about 95.5 per cent are traditional, 4.3 per cent transitional and 0.20 per cent modern hives (beyene and david, 2007). the traditional beekeeping accounts for more than 95 per cent of the honey and beeswax produced in the country. in ethiopia, honey has long tradition and cultural values, for instance as a gift in dowries during marriage, as an important ingredient for processing honey wine locally called tej © cncs mekelle university 78 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 brewery and beeswax is used to produce light particularly in the orthodox churches (beyene and david, 2007). in ethiopia, beekeeping is an integral part of the life style of the farming communities, and except for a few extreme areas, it is a common practice in every place where humankind has settled. in addition, ethiopia has probably the longest tradition of all the african counties in beeswax and honey marketing. the time is immemorial as to when and where marketing of honey and beeswax has been started in the country (beyene and david, 2007). the national average honey produced for the year 1997 to 2004 was estimated at 30 thousand metric tones, which accounted over 23 per cent of the total african production and about 2 per cent of world honey production (moard, 2005). production of beeswax was three thousand tons per annum placing the country among the four largest world beeswax producers (ibid, 2005). in the country, it is estimated that around one million farmer households participate in beekeeping. honey is produced mainly as a cash crop, which is serving as a source of additional cash income for hundreds of thousands of farmer beekeepers. honey is mainly produced for market. more than 95 per cent of the total produced is marketed, while the remaining is used for home consumption. in addition, a significant number of people are engaged in production and trading of honey at different levels and selling of honey wines (local beverage tej) which create job and self-employment opportunities for large number of citizens. export of honey and bee wax is estimated to contribute an average of 1.6 million usd to the annual national export earnings (ethiopian customs authority and export promotion agency, 2006). many factors are pointed out as causes for unemployment in rural areas of ethiopia. the commonly mentioned ones are drought; sever physical environmental degradations, very low levels of investment in the agricultural and non agricultural sectors, lack of non-farm employment activities, lack of skills and adequate initial capital to run income generating activities and poor rural-urban linkages. although the annual production of both honey and wax in ethiopia is large compared to other african countries, the system of production commonly exercised in the country is traditional. productivity of honeybees is very low and only an average of 8-15kg of honey could be cropped per hive per year. however, in areas where improved technology has been introduced, an average of 15-20 kg/hive/year has been recorded. ethiopia, having the highest number of bee © cncs mekelle university 79 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 colonies and surplus honey sources of flora, is the leading producer of honey and beeswax in africa. on a world level, ethiopia is fourth in beeswax and tenth in honey production (ayalew and gezehegn, 1991). in tigray region, northern ethiopia, apiculture is a good source of income for smallholder farmers, as both honey and bee colonies are in high demand. to increase the yield and improve the quality of honeybee resources in the region, the tigray government introduced modern (kenya top-bar) beehives and accessories. however, because this equipment is relatively expensive to buy, most smallholders could not increase their income as had been expected. some innovative beekeepers started to use alternative equipment and practices to manage their bee resources and to improve the quality of the products (hailu et al., 2007). the theme of this investigation was to examine the technological constraints, honeybee pests and their management, and asses the production systems under practice. figure 1. map of tigray showing the different sampled zones. © cncs mekelle university 80 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 2. materials and methods 2.1 study area the study area, tigray, is the northern most region of ethiopia located on the sudano-sahelian dry land zone. it covers an approximate area of 50 thousand square kilometer with an average population density of about 65 persons/km2 and population growth rate of about 3 per cent. most of the area is arid or semi-arid with annual precipitation of 450–980 mm. mostly the rain falls within the months of june, july and august, exhibiting high intensity and high temporal and spatial variability (berhanu, 1998). more than 85 per cent of the regional population lives in the rural areas and depends on mixed crop–livestock subsistence agriculture. 2.2 assessment and diagnosis a three-part assessment and diagnostic study was undertaken focusing on: 1) the honeybee production and beekeepers livelihood system 2) honeybee production needs and problems, and 3) pests affecting honeybee production and their management practices. this phase combined a macro-level analysis for understanding the dynamics of the overall integrated honeybee management (ihbm) livelihood system, with a micro-level analysis to identify specific technological needs and opportunities for honeybee production, particularly integrated pest management in honeybee. results of the livelihood systems assessment were used to identify whether honeybee production is a major source of cash income supporting the livelihood of a wide range of households/groups –bee keepers, traders and honey and wax processors. the results were also used to look for key technological and market constraints affecting honeybee production system. the assessment was used in the identification of windows of opportunities for participatory technology development (ptd) seeking to address technological constraints: incidence of pest and disease complex, quality of honey products and limited technological knowledge of the bee keepers. while nontechnological in nature, market-related constraints were likewise addressed in subsequent phases by developing capacity of farming households to cope with the dynamics of markets and prices. questionnaires were developed and administered to one hundred nine-teen randomly selected beekeepers in all zones of tigray to obtain data related to market and technological constraints, government support for the honeybees sub sector, bee pest management, adopted technologies etc. the researches’ direct observation of the area has also generated some data. key informant © cncs mekelle university 81 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 interviews were carried out to obtain information on the honeybee pests, pest management under practice, introduced technologies etc. the informants included community elders, extension workers working at the study sites and peasant administration (pa) officials. focused group discussions were held in study communities. the participants were representatives from different farmers, from various kushets, from different economic strata and from both sexes to maintain gender balance. the participants expressed their own feelings (perceptions), and offered their experiences regarding the issues under study. 3. results and discussion 3.1 honey marketing and quality 45.7 per cent of the bee keepers households responded “yes” for the question “is bee keeping a major source of cash income supporting the family livelihood ?” and the majority (54.3 per cent) “no”. this suggests that beekeeping is not a major source of cash income for many of the farmers but as a supportive income to meet their demand for cash to pay debts and for their living conditions. there was variation in the amount of money earned. the results also showed that the amount of money earned per year was generally low or too little to sustain the needs of the households. coupled with the low local demand for honey, the respondents noted that the income from honey production is unsteady. beekeepers sell the largest proportion of their honey during harvest at low price to meet their demand for cash to pay taxes, debts and other social obligations (beyene and david, 2007). the market for honey is generally poor, mainly due to a limited number of buyers, poor market infrastructure and poor market information. according to the households large quantities of honey are supplied to tej houses in their areas. another problem of the respondents was related to the production, pricing and marketing of honey. the beekeepers noted that the amount of honey harvested tends to fall below their expectations. prices offered for their honey are generally low. bees and beekeeping contributes to sustainable rural livelihoods not only through production and sale of honey and its bi-products, but also through maintenance of biodiversity and increase in crop production through bees pollinating services. in terms of nutritional and economic benefit to people, the role of bees in crop pollination is even more important than their role as producers of honey and other products. in the absence of pollinators mainly honey bees, vegetable and seed crops and tree crops yield loss was estimated to be 26 and 43 per cent, respectively (buchmann and nabham, 1995). bees are © cncs mekelle university 82 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 essential components of every ecosystem, maintaining biodiversity through pollination, and honey production is therefore highly sustainable. of the total beekeeping households interviewed, majority (72.3 per cent) (table 1) responded poor quality for the question “how do you classify the quality of honeybee products? good quality honey was harvested from modern hives and poor from the traditional ones. they produce a low quality product that they are forced to sell locally to wholesale buyers at prices much lower than in domestic commercial markets. this poor quality of honey is probably attributed to the bee forages and bee management practices. majority of the production practice are still very traditional and results in poor quality and quantity of honey. the type of hives used the methods of removing and storage of honey play a vital role in the quality of honey (crane, 1970, as cited by edessa negera, 2005). the knowledge and skill of honey production and honey and beeswax extraction of ethiopian farmers is still very traditional (moard, 2006). low productivity and poor quality of bee products are the major economic impediments for rural beekeepers (nuru, 1999). the total honey production of ethiopia is estimated up to 24000 metric tones; only a small amount of this is marketed. besides poor marketing conditions the main reason is that about 80 per cent of the total ethiopian honey production goes in to the local tej-preparation, a honey wine, which consumed as national drink in large quantities (hartmann, 2004). even though honey satisfies the local demand, it is so crude that it cannot compete in the international market (ministry of trade and industry, 1995). export of honey and beeswax is estimated to contribute an average of usd 1.6 million to the annual national export earnings (eepd, 2006). table 1 response of households for the question “how do you classify the quality of honeybee products? response number of respondents percentage good quality 33 27.7 poor quality 86 72.3 total 119 100.00 they were also asked, “are you aware that ethiopia is one of the major exporters of honey in the world? ethiopia is fourth in beeswax and tenth in honey production. 99 per cent responded “no” indicating that they do not realize that their country ethiopia is rich in honeybee and wax © cncs mekelle university 83 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 production. only one per cent of the respondents responded “yes” indicating that they were aware that ethiopia is a leading producer of honey in africa. 3.2 honey yield, production practices and honey bee flora honey yield was markedly different for the traditional and modern hives. on average, it was about 8-15 kg/hive and 20-30 kg/hive from the traditional and modern hives respectively. high variability in yield was observed within the farmers. this is most probably due to differences in management of bees, and from exogenous factors such as climate changes, pests and diseases.there is a significant difference between the mean yield obtained annually between the traditional and modern hives. even though apiculture presents an opportunity for small producers, for many beekeepers the potential to create a significant livelihood from selling honey remains out of reach. honey is produced at house hold level by beekeepers. harvesting is conducted ones or twice a year. this is probably attributed to the natural flora of the localities. as is the case in many other areas of the country, beekeeping in tigray is also mainly based on traditional systems. in tigray land degradation and removal of vegetation cover are very high. the principal bee flora for beekeeping has become seriously degraded in the course of time. the bees and the plants they depend on, like all renewable natural resources, are constantly under threat from lack of knowledge and appreciation of these endowments (girma, 1998). yet, despite such big challenges, there are a wide variety of plants which are used as honeybee flora. in some areas there is active planting of nectar yielding vegetation. in some places the beekeepers themselves have endeavoured to redress the situation by planting good honey plants near their hive colonies. despite such local improvements, which in some places are spectacular, the bee-keeping resource base is still deteriorating in some areas. the interviewed beekeepers responded that eucalyptus trees, herbs, weeds, cultivated crops, shrubs, and some woody plants are the main honey sources. 3.3 adoption of technologies great effort has been made by government extension package and relief society of tigray (rest) to adopt movable frame hive technology to the region to increase quantity and quality of honey production and for better management of bees. this recently introduced new technology has shown significant improvement in the management of hives, bees and production of honey and wax. the beekeepers were asked whether technology/innovations are available to improve © cncs mekelle university 84 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 the production of honeybee in tigray. majority of the respondents (89.9 per cent) (table 2) answered “yes” indicating that there are technologies for improving honey production in the region. the rest of the respondents (10.1 per cent) answered “no” indicating that they did not know that technologies are available for honey bee production in tigray. this indicates that lack of awareness on production technologies is also another concern that the regional government should address. table 2. response of household beekeepers to the question “are new technologies introduced available to improve the production of honeybee in tigray. response number of respondents percentage yes 107 89.9 no 12 10.1 total 119 100.00 81 respondents who had adopted new technologies of bee keeping were asked, “is there an increase in your production after you apply new technology/ innovation in honey bee keeping’’? they all answered yes; there is an increase in honeybee production after applying the new technologies. though the respondents had adopted modern methods of bee keeping, they still kept traditional beehives. they practice both traditional and modern methods of bee keeping. all the households applying the new technologies responded that there is a significance increase in their production after they apply the new method of beekeeping. however, their traditional beehives have not been completely replaced by the adoption of modern beehives. kerealem (2005) showed that adoption rate of improved box hives is low in ethiopia and highlighted the importance of investigating factors influencing the adoption of improved box hives. the large ucing honey using traditional hives (moard, 2003). traditional methods need to be replaced by the improved and modern scientific methods for better management. nevertheless, the use of improved modern beehives has not gained wide popularity mainly due to high cost. figure 2. centrifugal majority of beekeepers in the country are still prod honey extractor machine. © cncs mekelle university 85 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 there is a significant increase in honey production after they apply new technology. other new y table 3. adoption of new technology in time span in tigray region, northern ethiopia. technologies are also introduced including, mechanical centrifugal honey extractor (fig. 2), casting mould, sprayer, and bee smoker. the centrifugal honey extractor machines were imported from italy. in an attempt to reduce the cost of importing the machines, mesfin industrial engineering (a local industrial engineering) is now providing the machines. however, almost all of the locally made centrifugal honey extractors are not working properly. of the interviewed 119 beekeepers 81 beekeepers are applying new technology to enhance hone production and increase their income, of which only 15 have been using the technology for more than 5 years and the majority (66) have been using the technology for less than 5 years (table 3). although beekeeping is an old age practice in the region, adoption of recently introduced technology is very low and poor. however, adoption of the new technologies is a continuous process. bee-keeping in tigray is practiced in an unscientific and crude way. though new modern hive has been introduced in the region, it has not gained wide popularity due to high cost and lack of awareness. years number of respondents percentage less than a year 16 19.8 1-2 years 24 29.6 2-5 years 26 32.1 more than 5 years 15 18.5 .4 market and honey production constraints and technological constraints and problems 3 respondents were asked to state the market associated with honey and wax production practices. according to the beekeepers, the critical constraints and problems affecting honey production in tigray region include inadequate availability of production technologies, limited availability of bee flora mainly due to deforestation, lack of beekeeping knowledge/skill, and marketing accessibility. perhaps the main constraints limiting the expansion of beekeeping may be the limited flora attributed to land degradation and deforestation. yet, there is a potential for beekeeping in the region. sometimes training is given for those who have modern bee hives only in churches. however, farmer’s access to trainings is generally poor. other major constraint facing the sub sector is a weak © cncs mekelle university 86 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 market which led to lower contribution of honey sub sector (much lower than its potential) to the regional and national economy. the traditional beehives are not comfortable for sanitation and high level of production. there are critical needs to introduce new movable frame hive technology to increase quantity continues, honey and beeswax production will be seriously sted with insects and infected with disease pests. and quality of honey production and training on apiculture farming. modern bee-keeping is relatively expensive that requires a good financial base, which most farmers often lack. the movable frame hive is so expensive that poor beekeepers are not able to buy it. farmers are complaining that the cost of the modern hive is so expensive; at first the cost was 350 birr, but now, it costs about 650 birr excluding the interest. this increment in cost hinders poor farmers not to buy it. all these constraints are further aggravated by inadequate extension coverage, lack of special skills and limited research works in the beekeeping sector. inadequate vegetation coverage for bee colonies (bee forage), lack of proper bee management, and inadequate government support are other factors responsible for failure of large scale growth of apiculture in the region. most of the rural beekeepers cannot afford to invest in inputs, process, pack, and transport their products to market to maximize profit. moreover, lack of proper marketing channels, lack of trained development agents, poor market infrastructure are generally the major factors hampering the apiculture development in the region. lack of appropriate production technologies, weak market and absence of value chain development largely resulted in much lower contribution of the honey sub-sector, much lower than its potential (wilson, 2006 and tallonitire, 2006). if deforestation and land degradation affected. trees that provide bee forages are being cut by the farmers to extend the agricultural fields. according to the beekeepers response, limited supply of honey due to limited availability of bee forage (due to deforestation), shortage of honey bee colonies, back ward technology, in adequate government support, high cost of improved technologies, weak market infrastructure, low quality, poor pre and post harvest management, lack of market information are current problems facing the sub sector in the region. 3.5 honey bee pests and their management like all living organisms honeybees can be infe some of these pests are more deleterious to bee colonies than others, but it is important for the © cncs mekelle university 87 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 beekeepers to be able to recognize conditions which might be pest related and respond accordingly. ba figure 3. a. honeybee management option designed to float pests on the water; b. applications of ash and dirty engine oil to protect bee pests (insect repellents). beekeepers were interviewed on the presence of bee pests and their control and management strategies. according to the beekeepers response there are multitudes of honey bee pests including; ants (both black and red) and ant like insects (the greatest enemies), birds, spiders and lizards. traditionally, farmers have their own control means including the application of ash, rope around entrance of hives (hanging the predator’s neck), insect repellents (such as dirty engine oil), snap and light traps, mechanical killing of the pests etc. pests were also protected through placing the wooden top-bar beehives on a small can containing water so as to float pests on the water (fig. 3a). however, this pest management option is suitable only for the modern beehives. all the four legs of modern beehives are also protected by insect repellents such as dirty engine oil (fig. 3b). each leg of the stand is placed in a shallow container full of oil. several other insects are also protected by spreading wood ash around the stand of the beehives (fig. 3b). generally, as the pests are attracted to wards sweets such as honey sugar, nectar and bee’s body, beekeepers should be able reduce the damage and protect the hives through the above mentioned and other related management options. © cncs mekelle university 88 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 government should give enough attention and take beekeeping in to consideration as one of the strategies for reducing poverty and ensuring household food security. the regional government should provide regular training for beekeepers and facilitate financial services. the respondents were asked “are there agencies that helped in improving the honeybee production system in your woreda/kebele? of the total respondents only 37.8 per cent answered “yes” which implies there are agencies that helped the sub sector. the majority (62.2 %) answered “no” indicating that they were not helped to increase their honeybee production and enhance their incomes. this shows that there is inadequate government support to enhance apiculture in the region. according to the bee keeper’s response, rest (a local ngo) together with bureau of agriculture and natural resource development are now providing financial and technological supports to the honey sub sector. however, the support given to enhance honeybee and wax production is generally poor. several other insects attack honey bee colonies, including several species of ants, bee mites, bee louse (braula coeca). in his attempt to improve his living conditions, man has caused and is still causing great damage to nature. trees that support bee life are being destroyed. bee populations are also declining through large scale extensive agriculture. hence, man is perhaps the greatest pest of honeybee. 4. conclusions and recommendations we have identified the major constraints affecting honey and beeswax production in tigray regional state, ethiopia. these constraints include inadequate availability of production technologies, limited beekeeping knowledge, limited availability of vegetation, limited training and technical assistance in beekeeping and honey marketing. lack of proper bee management and marketing facilities are also problems facing the honey sub sector in the region. these constraints are further aggravated by inadequate extension coverage, lack of special skills and research undertaking in the beekeeping sector. because of these and other related factors, the region and the rural beekeeping households have not been sufficiently benefited from the honey sub sector. there have been a long tradition and culture of beekeeping in the region, nevertheless, productivity and production of honey bee is not developed yet. hence, the government should give enough attention and take beekeeping into consideration as one of the strategies for © cncs mekelle university 89 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 reducing poverty and ensuring food security, and further attain mdg (millennium development goals). adequate supply of modern beehives, encouraging participation of households in beekeeping and increasing their production through planting bee plants, facilitating financial services and regular training are critically important to increase production of honey and wax on a sustainable base in the region. adequate government support is required to increase incomes of beekeeping households. to empower the poor and promote improved honey production technologies, conservation of natural vegetation, introducing multi-purpose trees and potential bee forages should be strengthened to benefit the beekeepers. furthermore, training and technical assistance should be given at grass root level on regular bases. beekeeping in tigray is still very traditional with little intervention with modern production practices and is carried out in home gardens, in bushes, and area enclosures. the traditional beehives are made from wood, dung, and mud. beekeeping plays a major role in socio-economic development and environmental conservation. it is a source of food (e.g. honey). it contributes to the incomes of households. a significant number of people are also engaged in trading of honey at different levels and selling of honey wines (local beverage tej) which create job and self employment opportunities for large number of citizens. in tigray, deforestation, and overgrazing has nearly depleted the bee forage availability, ultimately resulting in low honey and beeswax production. however, there is still potential to increase honey production and to improve the livelihood of the beekeepers. the government also need to develop apiculture as one of the strategies to reduce poverty and ensure sustainable development. hence, to alleviate poverty, sustain development, conserve natural resource, and secure small producers livelihood, there is a strong need to help households engaged in beekeeping thorough; trainings, research, and provision of adequate and appropriate production technologies. 5. acknowledgments the authors gratefully acknowledge the support of norad ii for funding this research. we are also very grateful to the study area communities and development agents for their very kind support throughout the study. © cncs mekelle university 90 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 6. references arsd (apiculture research strategy document). 2000. apiculture research strategy document. earo (ethiopian agricultural research organization), addis ababa, ethiopia. ayalew, k & gezahegn, t. 1991. suitability classification in agricultural development, ministry of agriculture, addis ababa, ethiopia. berhanu, g.1998. the economics of soil conservation investments in the tigray region of ethiopia. ph.d thesis, department of agricultural economics: michigan state university, east lansing, usa, 258pp. beyene, t & david, p. 2007. ensuring small scale producers in ethiopia to achieve sustainable and fair access to honey markets. paper prepared for international development enterprises (ide) and ethiopian society for appropriate technology (esat), addis ababa, ethiopia. buchmann, s. l & nabham, g. p. 1995. the forgotten pollinators. island press, washington, dc, usa. 292pp. edessa, n. 2005. survey of honey production system in west shewa zone. proceeding of the 4th ethiopian beekeepers association (ema), ethiopia. eepd (ethiopian export promotion development), 2006. export of honey and beeswax. draft report. eepd, ministry of trade and industry, addis ababa, ethiopia. ethiopian customs authority and export promotion agency 2006. annual report for the year 2005. gezahegh, t. 2001. apiculture development strategies, ministry of agriculture and rural development, addis ababa, ethiopia. gezahegn, t. 2001. apiculture development strategies. ministry of agriculture and rural development, addis ababa, ethiopia. gibbon, p. 2001. agro-commodity chains: an introduction, speech to odi, summer meetings series, http://www.odi.org.uk/speeches/gibbon.pdf girma, d. 1998. non-wood forest production in ethiopia. addis ababa, ethiopia. available from: ftp://ftp. fao. org/decrep/fao/003/x6690e00.pdf. [accessed on 25 september, 2007] hailu, a., yohannes, g., abera, g & ann waters-bayer. 2007. participatory research that builds on local innovation in beekeeping to escape poverty, rural development news 1/2007. © cncs mekelle university 91 gidey, y and mekonen, t (mejs) volume 2 (1): 76-92, 2010 hartmann, i. 2004. the management of resources and marginalization in beekeeping societies of south west ethiopia. international conference on bridge scales and epistemologies, alexandria, 1. kerealem, e. 2005. honeybee production system, opportunities and challenges in enebse sar midir woreda (amhara region) and amaro special woreda (snnpr), ethiopia. msc thesis, alemaya university, alemaya, ethiopia (unpubl.). moard. 2005. annual reports addis ababa, ethiopia ministry of trade and industry. 1995. annual external trade statistics, 1984–1994, addis ababa, ethiopia. moard. 2003. honey and beeswax production and marketing plan. amharic version. moard, addis ababa, ethiopia. moard. 2006. annual reports series 2005, 2006, addis ababa, ethiopia. nuru, a. 1999. quality state of grading ethiopian honey. proceedings of the first national conference of the ethiopian beekeepers association, addis ababa, ethiopia. tallontire, a. 2006. partnerships in fair trade: reflections from a case study of café direct. development in practice, 10: 166–77. wilson, r. t. 2006. current status and possibilities for improvement of traditional apiculture in sub-saharan africa. bartridge house, umberleigh, uk. © cncs mekelle university 92 research article http://dx.doi.org/10.4314/mejs.v15i1.8 momona ethiopian journal of science (mejs), v15(1): 105-116, 2023 ©cncs, mekelle university, issn:2220-184x submitted on: 5 th april 2022 revised and accepted on: 25 th january 2023 psychological characteristics of professional soccer players and their comparison with amateur players murad sultanov* a.i. garayev institute of physiology, ministry of science and education republic of azerbaijan, baku, azerbaijan (*murad.sultan.81@mail.ru). abstract the purpose of this study was to test the association between personality traits and competitive anxiety among professional soccer players and amateur soccer players (n=78), whose ages ranged from 17 to 21 years. personality traits were defined using the eysenck personality questionnaire (translated and adapted version). participants completed the sport competition anxiety test by martens to assess their state of anxiety. the study revealed the dominance of sanguine and choleric temperament, corresponding to extraversion in the representatives of both groups. a one-way anova demonstrated a statistically significant difference (p ≤ 0.03) between the competitive anxieties of the two groups. the results of the stepwise linear regression analysis demonstrated a statistically significant relationship (p ≤ 0.0001) between competitive anxiety and both psychoticism and neuroticism among professional soccer players. according to the results, psychoticism and neuroticism predict the formation of competitive anxiety in professional soccer players. in soccer, the level of competition causes personality differences by psychoticism and neuroticism, however, extraversion is the factor of preexisting differences, which draw any players into a team sport. coaches should spend more time on competitive games among youth players because it can help to adapt the autonomic nervous system and reduce excessive levels of anxiety. keywords: soccer professional and amateur, personality traits, emotion regulation, behaviour and temperament. 1. introduction psychological characteristics, including personality traits and competitive anxiety, are relevant factors in sports performance (moore et al., 2013; franklin et al., 2015). because anxiety as an emotional state and fundamental characteristic of personality is analyzed in many spheres of human activities: in the professional selection, pedagogic process, sport, and other fields where human adaptive possibilities should respond to the special requirements. anxiety manifests with a triple cognitive, physiological, and behavioral response to stimuli that are perceived as dangerous or threatening. it is a feeling of agitation and restlessness in response to certain situations. in this case, anxiety can reveal itself in different forms: in one man, his activity increases, while another one, in contrast, becomes motionless; in addition, some person’s behavior becomes inadequate and unmotivated. as most scientists propose, such diversity in reactions is related to the temperament peculiarities of each person (sultanov and i̇smailova, 2019). mailto:murad.sultan.81@mail.ru murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 106 issn: 2220-184x it is generally known that the basis of temperament is the same as the basis for individual characteristics of conditioned reflex activity, namely, the properties of the nervous system. combinations of the three main properties of the nervous system by pavlov (strength, balance, and mobility) are recorded as types of the nervous system, or types of higher nervous activity (haslam et al., 2017). this indicates that anxiety acts as a feature of temperament, in which high indicators of anxiety are always combined with relatively high rates of neuroticism and, apparently, are underlain by this innate indicator of typology of higher nervous activity. in sports science, the personality of athletes is being actively studied due to increased psychophysiological loads on the athletes’ body and their influence on sports results. for example, the problem of tolerance to different competitive situations and its relationship with personality traits and as well as the level of competitive anxiety among team sports players. according to some evidence, highly successful athletes have positive thoughts, better concentration and are more task-oriented, and also have lower levels of anxiety (ahmad and safdar, 2020). previous studies in the context of competitive sports have shown a coincidence between personality traits and success (allen and laborde, 2014), a distinct personality profile of athletes compared to non-athletes (garcía-naveira and ruiz barquín, 2013), and personality differences between different types of sports (allen et al., 2013; parma et al., 2017). according to martens, numerous types of research have concluded that athletes with higher levels of competitive trait anxiety tend to perceive competitive situations as more threatening than athletes with lower levels of competitive trait anxiety. it seems that individuals with high trait anxiety have some sort of cognitive bias, which allows them to pick out more threat-related information (martens et al., 1990). in addition, when anxiety is not managed or explained correctly, athletes lose control, and their performance levels decrease (sangari et al., 2012). on the other hand, regular involvement in physical activity is associated with improved cognitive functions (etnier and chang, 2009; marchetti et al., 2015). furthermore, the physiological effects of regular physical activity are associated with “good” changes in brain anatomy (chaddock et al., 2011; voelcker-rehage and niemann, 2013). previous studies also noted that the descriptive methods with subject variables, which compare already-existing groups of athletes and non-athletes on personality, cannot distinguish whether certain kinds of people were drawn into sport (the gravitational or selection hypothesis) or whether participation in sport contributes to the differences between athletes and non-athletes (the developmental hypothesis) (elman and mckelvie, 2003). however, sport may expose athletes to repeated emotional highs and lows, allowing their autonomic nervous system murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 107 issn: 2220-184x to adapt, diminishing its lability, leading to a lowering in neuroticism. this implies that neuroticism may not differ much between athletes and non-athletes in the early stages of participation, but it may decline over time with athletes but remain constant with non-athletes. in addition, there is experimental evidence that exercise activity can lower trait anxiety (mckelvie et al., 2003). this fact is supported by another study, which determined that baseball and football members of teams were significantly higher on the activity and lower on the neuroticism-anxiety scales than the general college population (o’sullivan et al., 1998). therefore, the aim of this study: (i) to determine among professional soccer players’ and amateur soccer players individual-typological features, (ii) to compare professional soccer players with amateur soccer players according to personality traits and competitive anxiety, and it was hypothesized that professionals would be different from amateurs by personality traits or competitive anxiety, and (iii) to examine the predictive factors of anxiety in both groups. 2. methodology 2.1. participants the participants included soccer players and amateur sport students, who learned at an undergraduate level (bachelors) and studied from first to fourth courses. age of all persons was 17–21 years. the studies were conducted on thirty-nine professional soccer players (m = 18.27, sd = 0.95) and thirty-nine students (m = 18.41, sd = 1.10) of sports university, who trained in “soccer” speciality and interpreted as amateurs. the group of professional soccer players had more training hours per week (9 vs 4.5) and a more intensive training process than the group of amateur players. professional players participated in the national youth (under‐21) soccer championship, and some players were members of the national youth soccer team. all soccer players and students were men with normal hearing and normal vision. furthermore, they did not have any psychiatric or neurological disorders or cardiovascular disease history. 2.2. measures 2.2.1. temperament type and personality traits temperament types such as choleric, melancholic, phlegmatic, and sanguine were defined using the eysenck’s personality questionnaire (epq) (101-items). the testing technique was also designed to reveal the following factors, characterizing the structure of personality: psychoticism, extraversion, and neuroticism. the questionnaire was translated to azerbaijani language and adapted in the department of psychology at the state university. murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 108 issn: 2220-184x 2.2.2. competitive anxiety to assess the state of competitive anxiety participants completed the sport competition anxiety test (scat). the scat by martens (martens et al., 1990) is a 15-item inventory that measures trait anxiety in sport performers. respondents were required to indicate their agreement with each item by selecting their preferred answer from three categories: ‘rarely’, ‘sometimes’, and ‘often’. the scores on this test range from 10 to 30. evidence of the test’s convergent validity comes from studies that show that it is correlated with various general anxiety inventories (lavallee et al., 2012). 2.3. procedures to assess the type of temperament, personality traits, and competitive anxiety participants completed the epq and the scat on the sheets themselves before or after training sessions and gave them to the researcher. both tests were approbation in previous studies (sultanov and i̇smailova, 2019; sultanov, 2020). in the early, players completed the epq and afterward – the scat. all tests were held for nearly four months: from january to may. all tests were collected before the covid-19 lockdowns in azerbaijan. 2.4. ethics approval the study was conducted in accordance with the ethical principles of the declaration of helsinki. the researcher obtained a permit from club management to participate in the study of soccer players. university students received course credits for their participation in the study. in addition, each participant provided verbal consent for testing. the researches were approved by the scientific council of the institute of physiology on march 12, 2019 (protocol no. 2). 2.5. statistical analysis the shapiro-wilk test was used to verify the normality of the data among participants. yates’s chi-squared test was used to compare types of temperament: sanguine and choleric (extraversion) vs. phlegmatic and melancholic (introversion) between two groups. one-way anova and tukey hsd was used to compare the level of competitive anxiety between the groups. spearman’s rho was used to control for intercorrelations between predictors. a stepwise linear regression model was used to analyse personality traits as predictors of competitive anxiety. the level of significance was set at p<0.05. statistical analysis of the collected data was performed using spss statistics for windows, version 23.0. armonk, ny: ibm corp. (usa) and “statistics kingdom”. murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 109 issn: 2220-184x 3. results competitive anxiety by the scat demonstrated lower data among soccer players compared to groups of students (table 1). hence, the one-way anova demonstrated a statistically significant difference between the competitive anxieties of the two groups (f=5.04; p ≤ 0.03). tukey-kramer post-hoc test also demonstrated equal data (table 2). the research revealed dominance of the sanguine and choleric types of temperament, corresponding to extraversion in the representatives of both groups. the intercorrelation between personality traits as predictors of competitive anxiety was within the range of r <0.5 by spearman’s rho (tables 3 & 4). table 1. descriptive statistics and cronbach’s alpha for personality traits among soccer players. professional players amateur players parameters mean sd α mean sd α psychoticism 5.13 3.27 0.34 5.23 3.55 0.34 extraversion 15.36 3.30 0.46 15.56 3.53 0.49 neuroticism 12.26 4.99 0.86 12.36 4.66 0.73 scat 15.54 3.05 0.43 17.23 3.59 0.44 table 2. tukey hsd/tukey-kramer post-hoc test statistics. pair difference se q lower ci upper ci critical mean p-value x1-x2 1.6923 0.5332 3.174 0.1905 3.1941 1.5018 0.02772 table 3. intercorrelation between predictors using spearman’s rho among professional soccer players (note: r < 0.5). . parameters parameters 1 2 1. psychoticism 2. extraversion -0.08 3. neuroticism 0.47 -0.13 table 4. intercorrelation between predictors using spearman’s rho among amateur soccer players (note: r ≤ 0.3). parameters parameters 1 2 1. psychoticism 2. extraversion -0.05 3. neuroticism 0.30 0.10 murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 110 issn: 2220-184x additionally, the mean, standard deviation, and cronbach alpha values were calculated for each subscale in both groups (table 1). the internal consistency among some personality traits demonstrated a relatively low level of reliability. it is assumed that one of the causes of this low score might be connected to two different languages (azerbaijani and russian), which were used in the study. of course, some scales require further improvement. for instance, five of the 15-items in the scat questionnaire are “buffer” questions (iwuagwu et al., 2021). according to some evidence, it was established that low alpha might be the result of conceptual heterogeneity rather than low reliability (tavakol and dennick, 2011). the study revealed a joint association between competitive anxiety and both psychoticism, neuroticism. thus, results revealed two predictors of personality traits in the group of professional soccer players. in particular, there was a statistically significant association between neuroticism and the scat scores (p ≤ 0.0001). psychoticism also demonstrated a statistically significant association (p ≤ 0.0001) with competitive anxiety (table 5). on the other hand, regression analyses in the group of amateur soccer players’ neuroticism as a predictor of competitive anxiety was not observed. in addition, regression analyses demonstrated a statistically significant relationship between psychoticism and competitive anxiety, however, this result was on the border (p = 0.0485) and strongly different from the group of professional soccer players. moreover, regression analysis did not reveal any statistically significant relationships between extraversion and competitive anxiety in both groups. table 5. stepwise linear regression analysis of personality traits and competitive anxiety among professional soccer players. parameters f(2,38) r 2 adj. t b p neuroticism 20.49 0.34 2.52 0.40 0.0001 psychoticism 13.40 0.40 2.10 0.33 0.0001 4. discussion first of all, it should be noted that the categories of team and individual sports are conceptually different based on interdependency, with team sports conceptually requiring a higher degree of collaboration and social interaction (wold et al., 2013). on the one hand, it was established that in soccer if several players accomplish close function on the pitch in that case revealed characteristic the conjunction of the personality traits. however, in other team sports, such as murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 111 issn: 2220-184x american football, in which players function differently pretty widely, the rate of personality traits has not been pointed by a specific “type” that is inherent in participants or change of personality, which occurs during an activity of this sport (cratty, 1983). systematic sports activity and a high level of competitive practice might likely be the cause for restructuring the emotional regulation of behaviour and social interaction during professional sports activities in soccer players. thus, the correlation between psychoticism and neuroticism might indicate this relationship (table 3). on the other hand, this is reinforced by the fact that this connection (the high correlation between psychoticism and neuroticism) was not revealed in the study among amateur athletes (table 4). the low scores for competitive anxiety in professional soccer players over time compared to amateur soccer players is consistent with evidence that regular exercise reduces anxiety (ledwidge, 1980; mckelvie et al., 2003; eagleton et al., 2007). in addition, some studies have demonstrated that high levels of competitive anxiety are associated with poor performance (scanlan et al., 2005; smith and smoll, 1991). it is likely that experienced players keep clear of psychological problems caused by negative and conflicting intentions or behavior, and have less anxiety compared to non-athletes or less experienced athletes. practice and experience enable athletes to identify the sources of and methods that reduce competitive anxiety (mottaghi et al., 2013). however, it may also be due to environmental factors, which could affect and interplay with the temperamental traits of elite soccer players. this is because, the role of team players, and changes in their position in the game, might provide frequent personal interactions between team members. these contacts may provide proper emotional support (eysenck et al., 1982; doug et al., 2006). personality traits of soccer players such as psychoticism and neuroticism are determined by both genetics and environmental factors (laceulle et al., 2013; van kampen, 2009). however, practical equality in our study between professional soccer players and amateurs by extraversion parameter (table 1) agrees with eysenck’s theory (eysenck, 1967) that extraversion is based on cortical arousal and team sports provide arousal, which seeks the extraverts (colley et al., 1985). in this case, there are no differences in whether extraverts are professional players or amateurs. in addition, our results were similar to those of team sports in another study (eagleton et al., 2007), however, had differences compared to groups of amateur soccer players and nonathletes, and it is likely that in their one’s typology, amateur soccer players might differ from both professional athletes and non-athletes and hold the intermediate link. murad sultanov (mejs) volume 15(1):105-115, 2023 © cncs, mekelle university 112 issn: 2220-184x 5. conclusions the current study provided that competitive anxiety differs in soccer players who have professional sports activities, in contrast to amateur players. these differences were expressed by a lower level of competitive anxiety and available in professional players the predictors of competitive anxiety among personality traits. psychoticism and neuroticism predict the formation of competitive anxiety in professional soccer players. coaches should spend more time on competitive games and various tournaments especially among youth soccer players because it can help to adapt the autonomic nervous system and reduce anxiety during competition. in contrast, extraversion seems strongly based on genetics and does not change during sports participation. thus, among soccer players, the level of competition causes personality differences by psychoticism and neuroticism, however, extraversion is the factor of pre-existing differences which draw players into a team sport. future research is needed to replicate and extend the present findings because this sample was relatively small and consisted of youth players. 6. acknowledgements author duly acknowledges the reviewers for their inputs in improving the quality of the paper. 7. reference ahmad, s & safdar, f. 2020. goal orientation, motivation, and competitive anxiety in players of domestic cricket in pakistan. pakistan journal of psychological research, 87-105, http://dx.doi.org/10.33824/pjpr.2020.35.1.6. allen, m. s., greenlees, i & jones, m. 2013. personality in sport: a comprehensive review. international review of sport and exercise psychology, 6(1): 184-208, 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health, and life satisfaction among youth soccer players and adolescents in a reference sample. international journal of sport and exercise psychology, 11(4): 328-340, https://doi.org/10.1080/1612197x.2013.830433. https://doi.org/10.1016/s0005-7894(05)80370-3 https://doi.org/10.17223/15617793/454/25 https://doi.org/10.1002/tsm2.72 https://doi.org/10.5116%2fijme.4dfb.8dfd https://doi.org/10.2174%2f1745017900905010009 https://doi.org/10.1016/j.neubiorev.2013.01.028 https://doi.org/10.1080/1612197x.2013.830433 research article http://dx.doi.org/10.4314/mejs.v15i1.1 momona ethiopian journal of science(mejs), v15(1):1-16,2023 ©cncs, mekelle university, issn:2220-184x submitted on: 11 th february 2022 revised and accepted on: 30 th january 2023 impacts of fines at morupule coal mine, botswana onalethata saubi*, raymond s. suglo and bheemalingeswara konka department of mining and geological engineering, faculty of science and technology, botswana international university of science and technology, palapye, botswana (*onalethata.saubi@studentmail.biust.ac.bw, suglor@biust.ac.bw, bheemalingeswarak@biust.ac.bw) abstract morupule coal mine (mcm) classifies fines as coal particles that are less than 3.35mm in size. fines are one of the problems mcm is facing and have occasionally led to penalties from some customers. this paper quantifies the fines generated in mcm from the working face to the run-ofmine stockpile and its economic and environmental impacts. data about the wash plant's production losses were collected through an examination of missed deadlines, stoppages due to tail-end blockages, and conveyor belt breakdowns using company reports. data on coal dust concentrations were obtained from the mine. it was found that the overall haulage system generates about 27% of the fines of the coal produced monthly. the total monetary loss per shift from production and the wash plant is bwp 418,285. coal dust concentration underground is kept within acceptable limits due to strict engineering control measures while it exceeds the required levels on the surface and is difficult to control as it is exposed to the atmosphere. as a result, the vegetation around the mining concession is affected by coal dust. keywords: fine generation, dust production, coal degeneration, economic impact, environmental impact. 1. introduction coal degeneration is the reduction in the size of coal by comminution leading to smaller particle sizes (ramos and goodwin, 1987). several factors affect coal degeneration which includes the cutting techniques of the continuous miner, belt conveyor speeds and drop heights of the transfer points and comminution of coal at the processing plant. coal degradation results in coal dust that has environmental impacts such as water and air pollution, impacts on the health and safety of workers, and adverse effects on mining equipment and machinery (halt, 2014). handling operations from the working face to the stockpile increases the amount of fines generated since factors such as abrasion during conveying come into play. this makes coal degeneration one of the most significant problems in coal handling. dropping coal from high elevations generates more fines compared with dropping it from lower heights. according to tavares and de-carvalho (2012), the transfer points also play a significant role in coal degeneration. ramos and goodwin (1987) concluded that the degradation of coal materials at transfer chutes results from the change in energy imparted to the materials. at mailto:onalethata.saubi@studentmail.biust.ac.bw mailto:suglor@biust.ac.bw onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 2 issn: 2220-184x the same speed, more massive coal particles tend to disintegrate more than lighter ones due to their higher momentum. speeding up the conveyor belt results in discharge angles becoming relatively large leading to an increase in the spread of projected materials (ramos and goodwin, 1987). a feeder breaker is an underground primary crusher for crushing coal before it is loaded unto the conveyor belt. the time taken by the feeder breaker to crush is essential because the longer it stays in the feeder breaker, the more fines are produced. cutting coal with a continuous miner requires a high level of efficiency to minimise fines generation. the cutting efficiency of continuous miners is dependent on the type of drum, conditions of the cutting picks and the operator’s skill as interactions between the cutter head and the coal face are imperative. the parameters that influence cutting efficiency include rake angle, back clearance angle, angle of attack and line spacing (raghavan et al., 2014). fines generation has some serious economic impacts in a mine such as blocking of the tail end of the conveyors and blockages at the wash plant which forces the operations at the wash plant to be periodically stopped. this leads to losses in production. fines also increase the risk of coal dust explosions. as reported by raghavan et al. (2014), coal dust also reduces visibility along haul roads which can lead to accidents. coal fines create consolidation problems as they tend to stick to the surfaces and surrounding particles which leads to blockages in the coal flow during processing and at the power plant. moreover, long periods of exposure of mine workers to coal dust generated during mining could result in lung diseases like silicosis and coal worker's pneumoconiosis (meijers et al., 1991; attfield and morring, 1992; vallyathan, 1994; porter and fittipaldi, 1998). fines generation also affects the environment in terms of air quality, vegetation, and soil degradation. fine coal dust particles which settle on the soil affect the quality and ph of the soil. dust deposition on the leaves of plants decreases photosynthesis (for example, chloroplast content and stomatal blockage) and affects the colour of the leaves and plant growth (bhuiyan et al., 2010; zhengfu et al., 2010). besides mechanical factors, other researchers have studied fines generation considering coal lithotypes, microlithotypes, minerals and chemical elements present in coal (terchick et al., 1963; sciezska, 1985; falcon and falcon, 1987; spero, 1990; spero et al., 1991; huggins, 2002; hutchings, 2002; sykorova, 2005; nie et al., 2016; bai et al., 2017). mcm has suffered penalties from some customers because of high fines content in the coal supplied to them. the fines generated has also led to blockages in the tail end of conveyors which results in production delays. this study attempts to determine the quantity of fines generated in mcm, a coal mine in botswana. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 3 issn: 2220-184x in addition, the economic and environmental impacts of fines generated are also studied, and the measures taken to address the problem are elaborated. 1.1. mine case study morupule coal mine (mcm) is located along the serowe-palapye road in central botswana with coordinates 22.5071 ºs, and 27.0264 ºe (fig 1). the morupule area comprises karoo sedimentary rocks which form the eastern margin of the greater karoo basin developed to the west of morupule. these sedimentary rocks consist of shale, coal, and sandstone of the middle and lower ecca group. botswana has significant reserves of coal on the east side of the country, including the morupule deposit, with 40 million tonnes of recoverable reserves that are proven (machete, 2012). figure 1. location of morupule coal mine, central botswana (makoba et al., 2020). mcm is an underground mine which employs room and pillar mining method to extract coal. continuous miners are used for cutting the coal and loading it into shuttle cars, which haul the coal and dump it into feeder breakers which crush the coal into smaller sizes before it is transported to the surface by conveyor belts. the mine produces metallurgical and thermal coal. after the screening process, coal with fines goes to the wash plant, where the separation between coal and gangue takes place based on the differences in their densities. medium to large-sized coal onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 4 issn: 2220-184x goes through the comminution and sizing processes. the primary consumers of thermal coal are botswana power corporation (bpc), botswana ash and the namibian power utility company (nam power). bpc requires coal products ranging from 3.35 mm to 32 mm and only allows up to 32% fines (-3.35 mm) in the final product for easier handling at the power plant. 2. methodology several types of tests were performed on coal collected from the mcm. four samples, weighing 20 kg each, were obtained from the four mining sections namely, south main 3/1, sm4/8, sm 4/5, and east main 1/1 (fig 2). eight samples of 20 kg each were also collected, three from conveyor belts (cb1 from 18-114, cb2 from 18-113, and cb3 from 18-102), two from the lowest transfer points (ltp1 from 18-114 and ltp2 from 18-108), and two from highest transfer points (htp1 from 18-102 and htp2 from 18-101). in addition, one sample of 20 kg was taken from the runoff-mine (rom) stockpile. figure 2. location of sample points at morupule coal mine. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 5 issn: 2220-184x the wash plant's production losses were determined through an examination of missed deadlines, stoppages due to tail-end blockages, and conveyor belt breakdowns using the company’s reports. data on coal dust concentrations was also obtained from the mine. the flow chart for the methodology is shown in figure 3. figure 3. flow chart for the methodology. the relative influence of feeder breakers, belt speeds and transfer points on fines generation at the run-off-mine (rom) stockpile based on particle size distribution is evaluated by the cosine amplitude method (yang and zhang, 1997). this method is used to obtain similarity relations between various parameters. the strength of the relation between the dataset is given by equation (1): rij = ∑ 𝑋𝑖𝑘𝑋𝑗𝑘𝑚𝑘=1 √∑ 𝑋2𝑚𝑘=1 𝑖𝑘 ∑ 𝑋 2𝑗𝑘𝑚𝑘=1 ------------------------(1) where, xi and xj are the input and output datasets respectively, with m being the dataset number. 3. results and discussion 3.1. nature of coal and fines generation the curves on the particle distribution and concentration of fines show that more fines were produced from sm 3/1 ( 12.65%) section compared to the other sections (fig 4a and b). sm 3/1 onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 6 issn: 2220-184x coal is the most friable ( 31.25%) of all the sections while sm 4/5 coal is the least friable (about 2.81%) (fig 4c). figure 4. coal samples from the mcm: (a) particle size distribution curve, (b) fines (%), (c) friability (%), and (d) minerals present in four sections (vol.%) (saubi et al., 2022). the fines generation at mine sections and the friability test results compare well with mineral matter (fig 4d) where quartz and pyrite are the most dominant in the sm 4/5 coal compared to the other sections. the average particle size distribution (psd) of coal after sampling from the rom stockpile shows that the average quantity of fines generated by the system is < 3.35 mm (fig 5). figure 6 shows the relative influence of feeder breakers (fb), belt speeds (bs) and transfer points (tp) on fines generation at the rom stockpile based on particle size distribution is evaluated by the cosine amplitude method (cam). onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 7 issn: 2220-184x figure 5. psd of runoff mine stockpile coal at the mcm. d27 is the size of the sieve from which 27% of the coal is passing. figure 6. sensitivity analysis using cam at the mcm. according to strength values obtained from the application of the cam, (fig 6) feeder breakers have the least influence, followed by the speed of conveyors, and finally, transfer points (height) is the most influencing parameter on fines generation at the run-off-mine stockpile (rom). the production in tonnes and percent of coal fines generated at the wash plant (fig 7) shows that fines generation is one of the significant factors that accounted for the production targets of the mine not being met at the wash plant for most of the months. this suggests that a significant amount of coal gets washed away as waste in the form of fines at the wash plant. most customers accept coal products with a limited percentage of fines. when the proportion of fines in onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 8 issn: 2220-184x the stockpiles is more than 20% of the overall stockpile, then the targets cannot be met at the wash plant, as fines should make only 0.5% of the coal feed into the plant. for example, bpc requires coal products with less than 32% fines. on average from january to december 2019, the fines contributed 0.9% of coal fed into the wash plant at mcm which is higher than the acceptable limit of 0.5% per year (fig 7). the anomalies occurred in august and november 2019 when more fines were generated while less coal was produced. this is due to a relatively weak seam that was encountered during mining in those months from the sm 3/1 mining section. figure 7. coal wash plant product at the mcm. the downtime due to blockages recorded at individual conveyor belts (fig 8) shows that the main conveyor belts (i.e., 18-108, 18-111, 18-112) had higher downtimes than section conveyor belts. the main conveyor belt 18-103 has the highest downtime of 18.22 hr per month. this is because belt 18-103 is connected to the tail-end of the conveyor belt system at the mcm. hence, fine coal particles tend to clog or accumulate at the end of the pulleys resulting in severe blockages. figure 8. blockages for individual conveyors at the mcm. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 9 issn: 2220-184x 3.2. economic impacts fines generation leads to blockages at the tail end of conveyors, which forces operations to stop resulting in delays and production losses. the performance of the conveyor belts at the mcm (fig 9) indicates that conveyor belt blockage is the major cause of delays than other conveyor belt problems. these blockages result from the generated fines. the cumulative delay from the conveyors is 77.57 hours every month, that is, an average of 3.37 hr/shift. the average coal production at the mcm in an 8-hour shift is 4,100 tonnes. therefore, the delays due to conveyor belt blockages led to a production loss of 575 tonnes per shift. figure 9. the mcm conveyor belt performance. the production losses versus breakdown times (fig 10) show that production losses are directly proportional to breakdown times. this was the general trend in all the months. the leading cause of conveyor breakdowns was tail-end blockages due to fines accumulation. figure 10. relation between production losses and conveyor breakdowns at the mcm. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 10 issn: 2220-184x the total monetary loss is calculated based on the following observations: coal price = bwp 650/tonne actual output (wash coal) = 370,060 tonnes in a year fines (wash plant) = 11.11% in a year acceptable limit = 0.5%/monthly × 12 = 6% in a year loss (fines) = 11.11% 6% = 5.11% production loss = 575 tonnes/shift economic loss from production = p650/tonne × 575 tonnes/shift = bwp 373,750.00/shift economic loss from wash plant = ( p650 tonne × 5.11% × 370,060 tonnes/year 12 months yr × 23 shifts/month ) = bwp44,534.57/shift the total monetary loss per shift is bwp 373,750 + 44,534.57 = bwp 418,284.57. 3.3. environmental impacts an assessment of the environmental impact of dust generation is carried out with the use of a leopold matrix as shown in table 1 as an impact identification tool. this also includes evaluating the impact significance of dust generation on the health and safety of workers and equipment. table 1. leopold matrix for impact identification. valued components coal handling operations cutting of cm hauling by shuttle cars transporting coal by belts stockpiling coal human health 3 9 3 6 2 6 6 9 machinery 2 8 3 8 2 5 2 5 air quality 3 6 2 7 3 7 8 9 total 61 56 43 136 in the leopold matrix, the magnitude for cutting of the continuous miner is low since this activity only affects the area where the cm is cutting at the section. loading and dumping of shuttle cars have low magnitude as well since they involve only specific areas where loading and dumping operations are done. the magnitude is also low for haulage by conveyor belts because it onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 11 issn: 2220-184x only affects the locations around transfer points where fines are generated. stockpiling of coal has the highest magnitude since it is done on the surface, and the coal dust gets dispersed into the atmosphere over a large area around the mine. the importance of all the activities is directly linked to human health as coal dust has detrimental effects on human health, leading to severe diseases such as black lung and lung cancer. the magnitude for cutting of the cm, loading, and dumping by shuttle cars in the leopold matrix is low because it only affects the machines. still, the value or importance is high since these machines are critical to coal mining and handling and any breakdown or delay from the cms causes serious production losses. the magnitude for conveying by belts (on the surface) and stockpiling of coal in the leopold matrix is high since these activities are exposed to the atmosphere and affect a more significant area around the mine. its value is very high since the coal dust in the atmosphere has effects on human health, soil and vegetation in the mine and surroundings. summarising the impact significance shown by leopold matrix, human health is affected by all activities in coal handling operations. however, activities such as conveying coal by belts and stockpiling have the most significant impacts on air quality around the mine. coal handling operations of high magnitude (extent of impact) have led to more impact significance (product of magnitude and value). stockpiling of coal being an activity with the highest impact significance. coal screening, stockpiling, and conveying are the primary sources of particulate matter (coal dust) dispersion at collieries. mcm monitors the air quality of its underground operations as well as above ground for occupational reasons. the results of the coal dust monitoring taken above the surface are shown in figure 11. figure 11. surface coal dust concentration in mcm. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 12 issn: 2220-184x figure 11 shows that the air quality around the mine is 0.30 g/m3 and that the botswana waste management act limits for particulate matter of 0.1 g/m3 based on the annual averaging period were also exceeded. the conveyance by belts (on the surface) and stockpiling of coal are exposed to the atmosphere. therefore, other factors such as wind play a role in dispersing the fines over a large area thus affecting a more significant area around the mine. as a result of this, fine coal dust particles settle on the soil and affect the quality and ph of the soil. dust deposition on the leaves of plants decreases photosynthesis in the plants and affects the colour of the leaves and plant growth. it was observed that the leaves of the vegetation around the area had dull green colour and most plants had stunted growth (fig 12). figure 12. pictures showing the impact of coal dust on vegetation in the mcm area. 3.3.1. mitigating environmental impacts engineering controls in the mine are the principal methods used to reduce exposure to respirable coal mine dust. engineering control measures include diluting the dust generated by providing adequate ventilation at the coal face, controlling the respirable dust created and entrained (with improved shearer drum design of the cm), and suppressing the dust generated utilizing water. machines such as continuous miners and roof bolters are not significantly affected by coal dust since they are designed with dust collection systems. in cases where dust collectors of the roof bolters show accumulations of dust between the filters and blower, the dust is removed by backflushing the system with compressed air. the continuous miner is remote-controlled in most onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 13 issn: 2220-184x cases to enable the operators to avoid dusty areas and remain in fresh air to minimise their dust exposure. the cms are also equipped with sound non-clogging water filtration systems to avoid cases where dirt and dust particles in the water line clog the spray nozzles. regular bit replacement and routine inspections of the cutting drum are done to minimise fines generation. as shown in (fig 13), the dust level concentrations are kept within the acceptable limits in the mine as the dust concentrations underground were all < 2 mg/m3. the mcm ventilation standards which comply with the mines, quarries, works, and machinery act chapter 44 of botswana limits the dust concentration underground to 2 mg/m3. the mine workers wear approved personal protective equipment and uniforms that are laundered each day. the protective clothing is inspected and maintained to preserve its effectiveness. the concentration of respirable coal dust is determined as a time-weighted average (twa) by collecting samples over an 8-hour shift for up to a 40-hr work week. figure 13. underground coal dust concentration in mcm. when it is observed that the respirable dust concentrations exceed the recommended exposure limit (rel) for respirable coal dust, workers wear respirators for protection until adequate engineering controls or work practices employed return the atmosphere to normal levels. due to these strict measures at the mine to prevent coal dust dispersion and inhalation by mine workers, there has not been any reported cases of coal worker's pneumoconiosis. 4. conclusions in this study, an attempt is made to quantify fines generation in mcm and determine the economic and environmental impacts. it is found that the overall haulage system from the working face to onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 14 issn: 2220-184x the run-off-mine stockpile generates about 27% fines of the coal produced monthly. the total monetary loss per shift considering losses from production and the wash plant is about bwp 418,285. fines generation is kept within acceptable limits underground due to strict engineering control measures, while the coal dust concentrations on the surface exceed the required limits as the coal is exposed to the atmosphere and it is difficult to control the influence of wind on it. therefore, the dispersion of coal dust has affected the vegetation in the mining concession. 5. acknowledgements the authors wish to extend their appreciation to morupule coal mine for their support and cooperation in providing all the required data. 6. conflict of interests the authors declare no conflict of interest regarding this work. 7. reference attfield, m. d & morring, k. 1992. an investigation into the relationship between coal workers’ pneumoconiosis and dust exposure in us coal miners. american industrial hygiene association journal, 53(8): 486-492. bai, t., chen, z., aminossadati, s. m., rufford, t. e & li, l. 2017. experimental investigation on the impact of coal fines generation and migration on coal permeability. journal of petroleum science and engineering, 159: 257-266. bhuiyan, m. a., parvez, l., islam, m. a., dampare, s. b & suzuki, s. 2010. heavy metal pollution of coal mine-affected agricultural soils in the northern part of bangladesh. journal of hazardous materials, 173(1-3): 384-392. falcon, l. m & falcon, r. 1987. the petrographic composition of southern african coals in relation to friability, hardness, and abrasive indices. journal of the southern african institute of mining and metallurgy, 87(10): 323-336. halt, j. a. 2014. factors influencing material loss during iron ore pellet handling. michigan technological university. huggins, f. e. 2002. overview of analytical methods for inorganic constituents in coal. international journal of coal geology, 50(1-4): 169-214. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 15 issn: 2220-184x hutchings, i. m. 2002. abrasion processes in wear and manufacturing. proceedings of the institution of mechanical engineers, part j, j. engineering tribology, 216(2): 55-62. machete, m. 2012. a history of coal and the morupule colliery, 1973-2005. botswana notes and records, pp 45-59. makoba, m., moalosi, t., agachi, p. s., muzenda, e & mamvura, t. a., 2020. characterization of botswana coal from two coal fields: mabesekwa and mmamabula to determine its coal rank. studia universitatis babes-bolyai, chemia, 65(2):243-246. meijers, j. m., swaen, g. m., slangen, j. j., van vliet, k & sturmans, f. 1991. long‐term mortality in miners with coal workers' pneumoconiosis in the netherlands: a pilot study. american journal of industrial medicine, 19(1): 43-50. nie, b., liu, x., yuan, s., ge, b., jia, w., wang, c & chen, x. 2016. sorption characteristics of methane among various rank coals: impact of moisture. adsorption, 22(3): 315-325. porter, a. l & fittipaldi, j. j. 1998. environmental methods review: retooling impact assessment for the new century. army environmental policy inst champaign il. raghavan, v., murthy, c. s & sastry, v. r. 2014. analysis of stresses produced and dust generation during rock cutting by ansys software. int. j. environ. sci., 5(3): 595-606. ramos, c. m. & goodwin, p. j. 1987. degradation of sized coal at transfer points. bulk materials handling, 7(4): 23p. saubi onalethata, suglo raymonds & bheemalingeswara konka. 2022. fines generation and its impacts at morupule underground coal mine, botswana. book chapter in the proceedings of mediterranean geosciences union (medgu), medgu-21-p1306, advances in science, technology & innovation (asti), springer nature (under publication). sciezska, s. f. 1985. new concepts for determination of pulverised properties of coal. fuel, 64: 1132-1141. spero, c. 1990. assessment and prediction of coal abrasiveness. fuel, 69(9): 1168-1176. spero, c. d. j. r. k., hargreaves, d. j., kirkcaldie, r. k & flitt, h. j. 1991. review of test methods for abrasive wear in ore grinding. wear, 146(2): 389-408. sýkorová, i., pickel, w., christanis, k., wolf, m., taylor, g. h & flores, d. 2005. classification of huminite—iccp system 1994. international journal of coal geology, 62(1-2): 85-106. tavares, l. m & de carvalho, r. m. 2012. modelling ore degradation during handling using continuum damage mechanics. international journal of mineral processing, 112: 1-6. onalethata saubi, raymond s. suglo and bheemalingeswara konka (mejs) volume 15(1):1-16, 2023 © cncs, mekelle university 16 issn: 2220-184x terchick, a. a., shoenberger, r. w., perlic, b & de rusha, l. f. 1963. mechanical and related properties of some eastern coals. [29 refs]. conference, american chemical society 145th national meeting, new york, division fuel chemistry, american chemical society journal, 7(2): 5388714 (osti identifier). vallyathan, v. 1994. generation of oxygen radicals by minerals and its correlation to cytotoxicity. environmental health perspective, 102(10): 111-115. yang, y & zhang, q. 1997. a hierarchical analysis for rock engineering using artificial neural networks. rock mechanics and rock engineering, 30(4): 207-222. zhengfu, b. i. a. n., inyang, h. i., daniels, j. l., frank, o. t. t. o & struthers, s. 2010. environmental issues from coal mining and their solutions. mining science and technology (china), 20(2): 215-223. research article http://dx.doi.org/10.4314/mejs.v15i1.7 momona ethiopian journal of science(mejs), v15(1): 89-104, 2023 ©cncs, mekelle university, issn:2220-184x submitted on: 26 th july 2020 revised and accepted on: 31 st march 2023 design and analysis of urban land lease price predicting model using batch gradient descent algorithm kifle berhane niguse* department of computer science and engineering, mekelle institute of technology, mekelle university, p.o. box 231, mekelle, ethiopia (*kifle.berhane@mu.edu.et). abstract standard and econometric models are appropriate for causal relationships and interpretations among facets of the economy. but with prediction, they tend to over-fit samples and simplify poorly to new, undetected data. this paper presents a batch gradient algorithm for predicting the rice of land with large datasets. this paper uses a batch gradient descent algorithm to minimize the cost function, j(θ) iteratively with possible combinations of θ0 and θ1 the number of iterations i=1500 and learning rates,α of 0.01, 0.02, 0.03 for the linear regression case and i = 100, α =0.3, 0.2, and 0.1 for the multiple regression case. the paper uses octave-4.0.3(gui) for implementing 129 samples of the lease bid price of mekelle city as training sets and feature inputs of two and three for linear regression and multiple regressions. using α = 0.01, the best fitting parameters found by training the dataset are θ0 = 6.02 and θ1 = 2.30 with a cost of j=67.82. the model predicts with an accuracy of 92.6% using lr and 91.15% using mlr for a 315 m2 land size. as the learning rate increases, the fitting parameters θ0 and θ1 increase and decrease respectively with an equal cost but the model’s prediction error increments slowly. with multiple regression, as the learning rate lowers, the model under fits prediction drastically (with an accuracy of 60%) with gradient descent and predicts with an accuracy of 91.5% with ordinary equations. so, prediction with ordinary equations provides the best fit for multiple regressions. keywords: batch gradient descent algorithm, cost function, feature scaling, learning rate, machine learning, regression. 1. introduction human beings have been passing through different revolutionary ages to make their living standard better than what their ancestors had lived. the industrial revolution age, the information technology age, and now the data science and artificial intelligence (ai) era are among the dominant ones, to mention a few. these all brought significant economic changes for every household. recently, the role of data science and ai, more particularly machine learning (ml) along with artificial intelligence (ai), has caught the thoughtfulness of economists (athey and imbens, 2019). ml is a set of procedures (algorithms). it is functional for big datasets for prediction, classification, fraud detection, and product recommendation (athey, 2017). machine learning applications are ready to lend a hand in attaining improved forecasting that is indispensable for economic policy formulation and targeting (el naqa and murphy, 2015). ml is kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 90 issn: 2220-184x not much concerned with questions about identification. but it brings better results when the destination is a quasi-parametric approximation or with several covariates in comparison to the size of observations (giles, 2018). ml is used for development interventions and impact evaluations in measuring outcomes and targeting treatments (mckenzie, 2018). there is a gap in the measurement of fundamental statistics. machine learning is better for the problem at the macroand micro-level (elena badilo, 2019). specialists in ml are becoming curious about ml if it helps target interventions, i.e., deciding when and where/for whom to intervene (mckenzie, 2018). ml techniques can be helpful for econometricians. ml approaches are so powerful computationally. subsequently, the intermingled use of econometric models with ml approaches helps to yield a resounding estimation and hence more multifaceted models (kleinberg and ludwig, 2016). the correlation between land lease prices and the macroeconomy is an imperative and inspiring reason for predicting land lease values. land lease price implications are not only an issue for consumers and suppliers (mekelle city administration), but it also signposts the present-day economic condition. consequently, it is significant to predict these prices without bias to assist both the consumers and suppliers in making their decisions. standard economic models are well appropriate to consider causal relationships between different facets of the economy, but when it comes to prediction, they tend to over-fit samples and occasionally simplify poorly to new, undetected data. econometric models are relatively modest and relaxed to interpret; ml methods address enormous amount of aggregated data, frequently without forfeiting interpretation. econometrics is to create causation, while ml aims to make accurate and actionable predictions. a significant benefit of ml is that it considers empirical analysis as algorithms that estimate (evaluate) and compare several other models. this approach contrasts with econometrics, where the researcher picks a model based on principles and estimations once (giles, 2018). however, the growth of ml in social studies is so slowmoving. social scientists have slowly but steadily begun leveraging ml techniques to gain new insights from data (kleinberg and ludwig, 2016). it is common to see that most of the researches in economics are generally very fascinated causality questions (e.g., how do consumers get into financial distress?) (varian, 2016). despite, several policy problems have prediction questions that need to be addressed (e.g., which consumers will become financially distressed?) (gharehchopogh, 2013). there have been studies on retail sales forecasting, stock market price, gold prices and estimation of gdp with kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 91 issn: 2220-184x regression models prediction that check on the goodness of fit, model fit and specification, and statistical significance is explored using linear and multiple linear regressions (wu et al., 2003). other methods of ml predicting algorithms are like svr and flexible ann (employing a special adaptive regularization term) on travel-time prediction and the daily cash demand for atm, respectively (wang and zhu, 2010). however, none of these studies used batch gradient descent algorithm for optimal parameters estimation and the minimization of the mse or the cost. that is the reason the author is motivated to apply linear regression, multi-regression and ml algorithms (batch gradient algorithm) with the given training set and feature inputs of the land lease price of mekelle city administration to contribute on better prediction of macroeconomic questions by blending econometrics and ml approaches. the line of best fit would be, using the model coefficients, such that it would be as close as possible to the actual dataset by minimizing the sum of the squared distances between each dataset and the line ℎ𝜃(𝑥) = 𝜃0 + 𝜃1𝑥. once 𝜃0 𝑎𝑛𝑑 𝜃1 are known, the model can be used to predict the response (price). the objective of the research is to minimize the cost function iteratively using gradient descent algorithm with optimal learning rate; by taking possible combinations of 𝜃0 𝑎𝑛𝑑 𝜃1 and finally, design a price and profit predictive model for better predictability and analysis with new feature inputs of the city administration like that of land grade, land size, land location, bid price and so on. 2. methodology 2.1. conceptual framework the model comprehends machine learning algorithms, data training sets, and feature inputs to design a predictive model with low cost (mse), optimal fitting line, and fast learning (fig 1). specifically, the cost function, hypothesis function, and batch gradient descent algorithm are presumed for the ml algorithm. the row entities (data training set) are, based on the mekelle city land lease size of 140 m2, 175 m2, 250 m2, and 300 m2. the column elements (feature inputs) treated are land size, land grade, and bid price. pictorial presentation of the whole conceptual framework is presented in figure 1. 2.2. description of the study area data used for the study is a secondary data source collected from mekelle city administration in the form of reports. the study employed correlation and experimental quantitative research. it used correlation methods to show the relation between explained and explanatory variables. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 92 issn: 2220-184x figure 1. conceptual framework. quantitative analysis is applied to predict the cause-and-effect relationship between the dependent variable and independent variables. all these procedures use machine learning and econometric tools devised on linear regression and multiple regression models. because land lease bid in mekelle city is every three months, that is, discrete and equally spaced time intervals. the study is, thus, conducted using a time series data method. 2.3. research approach of the study because predicting prices of the land lease is numeral in their inquiry mode quantitative approach is used to capture the in-depth and enormous data and information for systematic analysis and understanding of the performance. as prices are predicted by linearly relating parameters (features) of the model, the research is correlational by its objective and experimental based on the nature of the investigation. octave-4.0.3(gui), notepad++, and mathlab are used to implement the experiment. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 93 issn: 2220-184x in this paper, the researcher tested instrument regression (univariate and multivariate) and experienced to see it work on the given dataset. regression parameters like that of are made to fit the dataset using batch gradient descent algorithm by tuning suitable learning rates and the number of iterations to achieve minimum cost or mean square error. the objective of linear regression is to minimize the cost function in equation (1). cost function: 𝐽(𝜃0, 𝜃1) = 1 2𝑚 ∑ (ℎ𝜃(𝑥𝑖) − 𝑦𝑖) 𝑚 𝑖=1 2 -------------------(1) where, the hypothesis function ℎ𝜃(𝑥) is given by the linear model: ℎ𝜃(𝑥) = 𝜃 𝑇𝑥 = 𝜃0 + 𝜃1𝑥1 --------------------(2) hence, the parameters of the model are the 𝜃𝑗 values. for the regression possible feature input taken are land lease size (m2), land grade and the bid price. these are the values that are adjusted to minimize cost function𝐽(𝜃). the researcher approached this achievement by • trying a number of blends of 𝜃0 𝑎𝑛𝑑 𝜃1, learning rate and number of iterations • attaining at the line equation that satisfy most of the dataset • use the finalized line equation for predicting the new set of input values hence, the cost function rescues in identifying the optimal equation with the right combinations of 𝜃0 𝑎𝑛𝑑 𝜃1 to realize best fitting line and optimized model. for each prospective line equation, the researcher: • tried to predict the ℎ𝜃 value and took the difference from the actual ℎ𝜃 value which gives the error possible with that particular equation. • repeated the same for all the sample datasets available • squared all the errors as the interest is in the magnitude of the error, and sometimes the positives and negatives may cancel out leading to no conclusion. • took the average by dividing with the number of sample dataset the value, thus, arrived for each possible line equation is compared to derive the optimal line equation. the one with lowest mean square error (mse) is the one which can be picked as the model for future predictions. to minimize the cost function 𝐽(𝜃0, 𝜃1), one approach to do this is using the batch gradient descent algorithm stated next. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 94 issn: 2220-184x gradient descent algorithm: repeat until convergence { 𝜃𝑗: = 𝜃𝑗 − 𝛼 𝜕 𝜕𝜃𝑗 𝐽(𝜃0, 𝜃1); 𝜕 𝜕𝜃𝑗 𝐽(𝜃0, 𝜃1) = 𝜕 𝜕𝜃𝑗 1 2𝑚 ∑ (𝜃0 + 𝜃1𝑥1 − 𝑦𝑖 𝑚 𝑖=1 ) 2 for j=0, 𝜃0 𝜕 𝜕𝜃0 𝐽(𝜃0, 𝜃1) = 1 𝑚 ∑ (𝜃0 + 𝜃1𝑥1 − 𝑦𝑖) 𝑚 𝑖=1 for j=1, 𝜃1 𝜕 𝜕𝜃1 𝐽(𝜃0, 𝜃1) = 1 𝑚 ∑ (𝜃0 + 𝜃1𝑥1 − 𝑦𝑖) 𝑚 𝑖=1 𝑥1} standard and econometric models are appropriate for causal relationships and interpretations between facets of the economy. but with prediction, they tend to over-fit samples and simplify poorly to new, undetected data. this paper presents a batch gradient algorithm for predicting urban lease prices with large datasets. the paper uses a batch gradient descent algorithm to minimize the cost function, j (θ) iteratively with possible combinations of 𝜃0 𝑎𝑛𝑑 𝜃1, the number of iterations i =1500 and learning rates α = 0.01, 0.02, and 0.03 for the linear regression case and i = 100, α = 0.3, 0.2, and 0.1 for the multiple regression case. the paper uses octave-4.0.3(gui) for implementing 129 samples of the lease bid price of mekelle city as training sets and feature inputs two for linear regression and three multiple regressions. using α = 0.01, the best fitting parameters found by training the dataset are 𝜃0=6.02 and 𝜃1=2.30 with a cost of j=67.82. the model predicts with an accuracy of 92.6% using lr and 91.15% using mlr for 315 m2 land size. it became clear that, as the learning rate increases, the fitting parameters 𝜃0and 𝜃1 increase and decrease respectively with equal cost, and the model’s prediction error increases slowly. with multiple regression, as the learning rate reduces, the model under fits prediction drastically (i.e., with an accuracy of 60%) with gradient descent and predicts with an accuracy of 91.5% with normal equation. so, prediction with normal equations provides the best fit for multiple regressions. { 𝜕 𝜕𝜃0 𝐽(𝜃0, 𝜃1) = 1 𝑚 ∑ (𝜃0 + 𝜃1𝑥1 − 𝑦𝑖) 𝑚 𝑖=1 for j=1, 𝜃1 𝜕 𝜕𝜃1 𝐽(𝜃0, 𝜃1) = 1 𝑚 ∑ (𝜃0 + 𝜃1𝑥1 − 𝑦𝑖) 𝑚 𝑖=1 𝑥1 } kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 95 issn: 2220-184x in batch gradient descent algorithm, each iteration performs the update: 𝜃𝑗: = 𝜃𝑗 − 𝛼 1 𝑚 ∑ (ℎ𝜃(𝑥𝑖) − 𝑦𝑖) 𝑚 𝑖=1 𝑥𝑖 𝑗 (simultaneously update θj for all j ) --------(3) for every step of gradient descent, the parameter 𝜃𝑗 comes closer to the optimal values that will achieve the lowest cost value that is 𝐽(𝜃0, 𝜃1). for multivariate linear regression, possible feature inputs can be land lease size (m2), land grade, and price per m2. the land sizes and the prices in this paper’s dataset are much bigger than the land grade, almost 100 times bigger. that deters the gradient descent algorithm does not converge quickly. to avoid this feature scaling is made, so that gradient descent converges more quickly. the working principle of multivariate linear regression is the mean values of each feature must be subtracted from the data set then scale (divide) the feature values by their respective standard deviations. the standard deviation is a way of measuring how much variation there is in the range of values of a particular feature. the gradient descent for multivariate linear regression remains the same as the univariate linear regression except that there will be more features. the hypothesis function and the batch gradient descent update will remain unchanged (see equations, 2 and 3). in the multivariate case, the cost function can be written in the form indicated by the equation (4). 𝐽(𝜃0, 𝜃1) = 1 2𝑚 (𝑋𝜃 − �⃗�)𝑇(𝑋𝜃 − �⃗�) ---------------------------------(4) where, x= [ 𝑥1 𝑇 𝑥2 𝑇 ⋮ 𝑥𝑚 𝑇 ] �⃗� = [ 𝑦1 𝑦2 ⋮ 𝑦𝑚 ] • m is the number of sample datasets (training set). • 𝒉𝜽(𝒙𝒊) is the predicted output value (price). • 𝒚𝒊 is the actual output value (takes a feature and estimates price). • 𝜶 is learning rate. • 𝒙 is input variable/features. • 𝒙𝒊 is i th training example. • 𝟏 𝟐 shows minimizing one half the mean squared error makes the octave/mathlab easy. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 96 issn: 2220-184x 2.4. methods of data processing and analysis the collected dataset is first cleared (edited) at central editing in case of missing values. next, it is coded and organized in vector-matrix form. finally, it is processed with lr, mlr, gradient descent algorithm, and normalization procedures. the data processing flow chart of the used algorithm is shown below in figure 2. figure 2. data processing flow chart. the quantitative dataset generated from the sample selected from mekelle city administration land lease bid price is analyzed by writing program codes using the octave software by changing relevant parameters like that of theta (𝜃), number of iterations and the learning rate alpha (α) using both univariate and multivariate lrs. predicted price, cost function value and gradient descent values are used in reporting and explaining the results. 3. results and discussions 3.1. results with linear regression 3.1.1. scenario-a: α = 0.01 and i* = 1500 with the learning rate of α = 0.01 and number of iterations, i* = 1500, the fitting parameters and the minimum cost (mse) value for the sample of land sizes 315 m2 and 140 m2 are found to be 𝜃0= 6.02, 𝜃1 = 2.30 and 𝐽(𝜃0, 𝜃1) = 67.38 respectively (fig 3a, b and c). with these gradient descent fitting parameters, the prices predicted with the experiment for the samples are found to be birr 13,274.74 and 9245.20 respectively (table 1) whereas the actual average prices are 14,330.31 and 12,228.97 respectively. the prediction errors are 7.4% and 24.4% for the sample kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 97 issn: 2220-184x land sizes of 315 m2 and 140 m2. hence, this model best fits with a prediction accuracy of 92.6% and 75.6% for the first and second samples respectively (fig 3a). the simulated results for cost and the contour for scenario-a are illustrated in figure 3. (a) (b) (c) figure 3. linear regression fit line, cost and contour for α = 0.01 and i* = 1500 (a) training data with linear regression fit (b) surface (c) contour, showing minimum. 3.1.2. scenario-b: α = 0.02 and i* = 1500 if the learning rate increases to α = 0.02 with number of iterations, i* = 1500, the fitting parameter 𝜃0 increases to 7.76 and 𝜃1 decreases to 1.57 and the minimum cost (mse) value remains same for the sample of land sizes 315 m2 and 140 m2 (fig 4 a, b and c). with these gradient descent fitting parameters, the predicted prices are birr 12,722.51and 9968.26 (table1) respectively. as a result, this model best fits with a prediction accuracy of 88.78% and 81.5% for the first and second samples respectively (fig 4a). the simulated results for price, cost and the contour for scenario-b are illustrated in figure 4. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 98 issn: 2220-184x (a) (b) (c) figure 4. linear regression fit line, cost and contour for α = 0.02 and i* = 1500 (a) training data with linear regression fit (b) surface (c) contour, showing minimum. 3.1.3. scenario-c: α = 0.03 and i* = 1500 if the learning rate is further increased to α = 0.03 with number of iterations, i* = 1500, the fitting parameter θ0 keeps increasing to 8.47 and θ1 decreases to 1.28 and the minimum cost (mse) value remains same for the sample of land sizes 315 m2 and 140 m2 (fig 5 a, b and c). with these gradient descent fitting parameters, the predicted prices are birr 12,499.09 and 10,260.81 (table 1) respectively. therefore, the prediction accuracies are 87.22% and 83.9% for the first and second samples respectively (fig 5a). the simulated results for price, cost and the contour for scenario-c are illustrated in figure 5. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 99 issn: 2220-184x (a) (b) (c) figure 5. linear regression fit line, cost and contour for α = 0.03 and i* = 1500 (a) training data with linear regression fit (b) surface (c) contour, showing minimum. 3.1.4. scenario-d: α = 0.01 and i* = 750 if the learning rate is further increased to α = 0.01 with number of iterations lowered to, i* = 750, the fitting parameter 𝜃0 decreases to 4.35 and 𝜃1 increases to 3.00 and the minimum cost (mse) value remains same for the sample of land sizes 315 m2 and 140 m2 (fig 6 a, b and c). with these gradient descent fitting parameters, the predicted prices are birr 13,805.13 and 8550.72 (table 1) respectively. therefore, the prediction accuracies are 96.34% and 70% for the first and second samples respectively (fig 6 a). the simulated results for price, cost and the contour for scenariod are illustrated in figure 6. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 100 issn: 2220-184x (a) (b) (c) figure 6. linear regression fit line, cost and contour for α = 0.01 and i* = 750 (a) training data with linear regression fit (b) surface (c) contour, showing minimum (i* = number of iterations). the quantitative output (for the model parameters, mse and price) obtained after considering scenarios a d are summarized in table1 for the case of lr. table1. model parameters and results for lr. scenario theta found by gradient descent cost (mse) predicted price (birr) for sample land sizes 𝜃0 𝜃1 𝐽(𝜃0, 𝜃1) 315 m 2 250 m2 175 m2 140 m2 a α = 0.01 6.02 2.30 67.38 13274.74 11778.05 10051.10 9245.20 i* = 1500 b α = 0.02 7.76 1.57 67.38 12722.51 11699.51 10519.11 9968.26 i* = 1500 c α = 0.03 8.47 1.28 67.38 12499.09 11667.73 10708.46 10260.81 i* = 1500 d α = 0.01 4.35 3.00 67.38 13805.13 11853.49 9601.60 8550.72 i* = 750 note: i* = number of iterations and α = learning rate. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 101 issn: 2220-184x 3.2. results with multiple regression for α = 0.3 and i* = 100, the fitting parameters computed from the experiment are 𝜃0 = 11110.98, 𝜃1 = 640.15, and 𝜃2 = 674.27 (table 2) for the minimum cost value. the predicted prices for the two sample land sizes (using batch gradient descent algorithm) are birr 13062.20 and 9745.72. the prediction accuracy is, therefore, 91.15% for the 315 m2 sample land size and 80% for 140 m2. this prediction accuracy and values of best fitting parameters remain almost the same for learning rates of 0.2, and 0.1 (table 2). table 2. model parameters and results for mlr. scenario theta found by gradient descent predicted price (birr) for sample land sizes 𝛉𝟎 𝛉𝟏 𝛉𝟐 315 m 2 140 m2 a α = 0.3 i* = 100 using gradient descent 11110.98 640.15 674.27 13062.20 9745.72 using normal equation 7701.69 10.25 304.58 13062.20 9745.72 b α = 0.2 i* = 100 using gradient descent 11110.98 640.15 674.27 13062.20 9745.71 using normal equation 7701.69 10.25 304.58 13062.20 9745.72 c α = 0.1 i* = 100 using gradient descent 11110.69 640.36 674.06 13061.89 9745.29 using normal equation 7701.69 10.25 304.58 13062.20 9745.72 d α = 0.01 i* = 100 using gradient descent 7044.00 513.94 525.91 8587.19 5959.41 using normal equation 7701.69 10.25 304.58 13062.20 9745.72 note: i* = number of iterations; α = learning rate. however, when the learning rate is small, i.e., when α = 0.01, the prediction accuracy is found to be so low, i.e., 60% and 49% for land size of 315 m2 and 140 m2 respectively with gradient descent algorithm. conversely, for α = 0.01, the model predicts with an accuracy of 91.15% for the 315 m2 sample land size and 80% for 140 m2, if normal equation is used. hence, the model predicts best with gradient descent algorithm when the learning rate, α = 0.3 and number of iterations, i* = 100 and it predicts best with normal equation with same accuracy as batch gradient descent algorithm when α = 0.01 and i* = 100. it can be inferred that at α = 0.3, 0.2, 0.1, and i* = 100, the batch gradient descent algorithm learns fast with an appropriate kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 102 issn: 2220-184x learning rate as shown in figure 7(a to d) in order of preference. when α = 0.01 and i* = 100, the algorithm learns so slowly even though the performance of price prediction is the same as with what the batch gradient algorithm does. (a) (b) (c) (d) figure 7. gradient descent convergence for (a): α = 0.3, i* = 100, (b): α = 0.2, i* = 100, (c): α = 0.1, i* = 100, and (d): α = 0.01, i* = 100. therefore, the best price predictor mode would be when α = 0.3 and i* = 100 (fig 7a) in 𝜃0 = 11110.98, 𝜃1 = 640.15, and 𝜃2 = 674.27 with a minimum cost value as shown in figure 7(a) with mlr. figure 7 shows how and when the gradient descent converges or diverges. the quantitative output (for the model parameters and price) obtained after considering scenarios a d is summarized in table2 for the case of mlr. 4. conclusion each iteration in this paper is performed simultaneously using the gradient descent update (algorithm). for every step of gradient descent, each fitting parameter gets closer to the optimal kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 103 issn: 2220-184x values that achieve the lowest cost value. the cost decreases with each step and iteration; the cost function has never increased and proved that the gradient descent algorithm functioned appropriately and converged to a steady state value that the algorithm terminates on. the final parameters’ values helped to make price predictions on new input features. when the sample training set becomes large, the cost function increases. learning rates are on a log scale such as 0.01. 0.02, 0.03, 0.1, 0.2, and 0.3 were in a better range. a too small learning rate led the batch gradient descent algorithm to converge slowly. a learning rate that is too small blows up and increases the value of the cost function. when the learning rate is too large, gradient descent overshoots the minimum failed to converge or diverge to some steady state cost value; the cost function was with a value of infinity. in the case of lr, using a learning rate of 0.01, the best fitting parameters found by training the dataset are 6.02 for theta1 and 2.30 for theta2 in order with a cost of 67.82; the model predicts with an accuracy of 92.6%. however, for mlr, the batch gradient descent algorithm converges fast with a learning rate of 0.3 and some iterations amounting to 100. the model achieves a prediction accuracy of 91.15% for the 315 m2 sample land size and 80% for 140 m2 with the best fitting parameters of 11110.98, 640.15, and 674.27 for theta0, theta1, and theta2 in order. this model predicts the price of urban land leases for mekelle city administration based on time series data trained with machine learning and econometric models unified for better optimality. designing such economic models enhances the predictability of important macroeconomic terms. as a result, consumers may be interested in how much to bid per square meter of the land lease in the city. the output of this research may support the government’s macroeconomic decisions, interventions, policy formulation, and targeting. 5. acknowledgments the author is highly indebted to mekelle city administration's core process of land management and development and to ms. seble assefa, urban land management expert at tigray regional state, for their generosity in the historical land lease prices datasets. the author is also thankful to maarig aregawi (assistant professor), mekelle institute of technology, mekelle university, teame hailemariam (assistant professor), college of business and economics, mekelle university, for their meticulous and relentless support and encouragement. kifle berhane niguse (mejs) volume 15(1):89-104, 2023 © cncs, mekelle university 104 issn: 2220-184x 6. reference athey, s. 2017. the impact of machine learning on economics. in: ajay agrawal, joshua gans, and avi goldfarb (eds.), the economics of artificial intelligence: an agenda, university of chicago press, isbn: 978-0-226-61333-8, http://www.nber.org/books/agra-1, conference volume, pp.507-547. athey, s & imbens, g. w. 2019. machine learning methods that economists should know about. annual review of economics, 11: 685-725. el naqa, i & murphy, m. j. 2015. what is machine learning? in: el naqa, i., li, r., murphy, m. (eds), machine learning in radiation oncology, 1: 3-11. elena badilo. 2019. the impact of machine learning on economics: what machine learning can (and cannot) do for economic research. chicago policy review. available at: https://chicagopolicyreview.org/2019/01/21/the-impact-of-machine-learning-oneconomicswhat-machine-learning-can-and-cannot-do-for-economic-research/ gharehchopogh, f. s. 2013. a linear regression approach to prediction of stock market trading volume: a cases study. international journal of managing value and supply chains, 4(3): 1-7. giles, a. 2018. machince learning and economics. financial conduct authority. availae at: https://spe.org.uk/site/assets/files/5204/adam_giles_slides.pdf kleinberg, j & ludwig, j. 2016. prediction policy problems. american economic review, 105(5): 491-95. mckenzie, d. 2018. how can machine learning and artificial intelligence be used in development interventions and impact evaluations? world bank blogs. available at:https://blogs.worldbank.org/impactevaluations/how-can-machine-learning-and-artificialintelligence-be-used-development-interventions-and-impact. varian, h. r. 2016. causal inference in economics and marketing. pnas.org, 113 (27): 7310-15. wang, l & zhu, j. 2010. financial market forecasting using a two-step kernel learning method for the support vector regression. annals of operation research, 174: 103-120 wu, chun-hsin., chia-chen, wei., da-chun, su., ming-hua, chang & jan-ming, ho. 2003. travel time prediction with support vector regression. proceedings of the 2003 ieee international conference on intelligent transportation systems : 2(2): 1438-1442. research article http://dx.doi.org/10.4314/mejs.v15i1.4 momona ethiopian journal of science (mejs), v15(1): 48-61, 2023 ©cncs, mekelle university, issn:2220-184x submitted on: 16 th october 2018 revised and accepted on: 8 th february 2023 willingness to pay for community-based health insurance and its correlates among households in wukro and setit-humera towns, northern ethiopia: a cross-sectional study goitom gigar1, gebremedhin berhe gebregergs2*, estifanos gebremeskel1, atakilti abrha3 and berihu mesfin1 1 tigray regional health bureau, mekelle, ethiopia. 2 school of public health, college of health sciences, mekelle university, mekelle, ethiopia (*bgebrish04@gmail.com). 3 ethiopian health insurance agency, addis ababa, ethiopia. abstract the study aimed to assess willingness to pay for community-based health insurance and its correlates among households in wukro and setit-humera towns, tigray, northern ethiopia for the year 2016. a community-based survey was conducted in wukro and setit-humera towns of the tigray region from august 30 to october 05, 2016. a total of 823 households were enrolled using a two-stage sampling. a structured, pre-tested, and interviewer-administered questionnaire was used. data were entered and analyzed using spss version 20. frequencies, mean, and median were calculated. bivariate and multiple variable logistic regressions were fitted. odds ratio with 95% ci was used to see the associations between selected independent variables and the outcome variable. willingness to pay for community-based health insurance (cbhi) in the two towns was 93.4% with 95% ci (91.6-95.0). the median amount of money that households are willingnessto-pay (wtp) was 11.1 usd. the mean amount of money an individual household is willing to pay was significantly higher in setit-humera than in wukro town. participants who knew their monthly income were two times more likely to be willing to pay for cbhi [adjusted odds ratio (aor) =2.6, 95% ci; 1.1, 8.1]; and willingness was higher among households who perceived that the cost of care is affordable in health facilities [aor=2.6, 95% ci; 1.02, 7.1]. the study has shown a high level of willingness to pay for health insurance. perceived affordability and knowledge of monthly income were significant factors that affect willingness to pay for communitybased health insurance. therefore, it can be operationalized in urban settings provided that the community is aware and sensitized focusing on the benefits of health insurance. besides, the premium needs to be carefully set to consider the community’s ability to pay. keywords: community health insurance, urban, willingness to pay, tigray, northern ethiopia. 1. introduction globally, 32% of health expenditure was out-of-pocket spending (who, 2015). in sub-saharan africa, people pay 60.2% of their health costs directly to healthcare providers out of their own pockets. the problem is serious in ethiopia in which the out-of-pocket (oop) expenditure goes as high as 78.1% (world bank, 2017). in many countries, the burden of oop spending is lowering goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 49 issn: 2220-184x health services utilization. furthermore, people who use health services may need to cut spending on basic needs such as food, clothing, housing, and children's education to meet health costs (oecd, 2011). different literature revealed that many people are willing to be enrolled and pay for community based health insurance (cbhi). in nigeria, the willingness ranged from 40 % to 72.7% (onwujekwe et al., 2010; oyibo et al., 2015), and in east africa, it ranges from 10% in kenya to 74% in rwanda (kimani et al., 2012; ina et al., 2016). however, the mean willingnessto-pay (wtp) amount is low and depended on many factors such as socioeconomic status, geographic differences, and past health expenditure for health care (onwujekwe et al., 2010; dong et al., 2005). there are desirable effects of extending health insurance coverage in many lowincome countries. this is because it reduces child work in the presence of parental health shocks in rwanda, and the scheme mitigates the health shocks effect of economic reforms on poor rural households in ethiopia (asfaw et al., 2004; woode et al., 2017). in two years of scheme operation in ethiopia, the cbhi uptake rate was 48 percent. at the same time, 82 percent of insured households renewed their subscriptions, and 25 percent of those who had not enrolled in the first year joined the scheme a year later (mebratie, 2015). in june 2014, cbhi scheme enrolment reached 52.4%, of which 44% were fee-paying and 8.4% received a waiver (ethiopian health insurance agency, 2014). in tigray, ethiopia, cbhi is already introduced in more than 20 districts and efforts are in progress to scale up region wide. previously, the willingness to cbhi and its determinants in a rural community of ethiopia have been investigated (yilma et al., 2014; fmoh, 2011, mebratie, 2015; ethiopian health insurance agency, 2014; obse et al., 2015). while there is a reason to believe that households in different contexts are volunteering to be enrolled in health insurance, determining the existence of willingness in the urban community is conceivable of great interest. thus, the present study is developed to assess the willingness to pay for community-based health insurance and its correlates among households in the urban community of wukro and setithumera, tigray, ethiopia. goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 50 issn: 2220-184x 2. methodology 2.1. study design, setting, and population a community-based cross-sectional study was carried out in wukro, and setit–humera, tigray, northern ethiopia from august 30 to october 05, 2016. wukro had a total population of 47611 in 10800 households. there were 4232 registered traders in the town. in setit-humera, there were 7794 households. it had a population of size of 34295, and 2585 traders. all households in the two urban districts were our study population. we interviewed heads of households that live for more than 6 months in the study area. 2.2. sample size and sampling technique we used a multi-stage (two-stage) sampling technique. of the 12 urban districts in the region, we included wukro and setit-humera purposively as they were the pilot areas selected for the implementation of community-based health insurance. first, two kebeles were selected randomly from each district. next, households were selected using the lottery method from the selected kebeles in both districts. four hundred twenty and 403 heads of households responded to the study in wukro and setit-humera, respectively. the overall response rate was 97.8%. we calculated the sample size using a single population proportion formula. we used a cbhi scheme enrolment rate, p= 52.4% (ethiopian health insurance agency, 2014), 95% confidence level, and 5% degree of precision. multiplying by the design effect of two and adding 10% for the non-response rate, the last sample size was 841. for a single population proportion, the formula to calculate the sample size is written below. n= (z α 2 ) 2 p(1−p) 𝑑𝑒𝑓 d2 ; where n=sample size; d = degree of precision; (z α 2 )= z sore for 95 % confidence level; p=proportion; def= design effect. n = (1.96)2(0.524)(0.476)∗2 0.052 = 765, then (10% none-response rate) =765×0.10=76. the final sample size was then: nf= 765+76=841 2.3. data collection tool and procedure data were collected using face-to-face interview techniques to collect information from each household. we used a structured and pre-tested questionnaire. the questionnaire was prepared in english and then translated into tigrigna. eighteen health professionals who have a bachelor of science were recruited from health facilities as data collectors. the head of each household was goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 51 issn: 2220-184x interviewed. data collectors and supervisors were trained for two days mainly on how to properly fill out the questionnaire, data collection techniques, and the purpose of the study. the study team supervised the data collection process. 2.4. data processing and analysis data were coded on the pre-arranged coding sheet by the study team. we cleaned and edited it manually. data were entered and analyzed using spss version 20. for normally distributed continuous data, results are presented using the mean ± standard deviation (sd), while for the skewed data, results are presented using the median (interquartile range, iqr). the descriptive results of categorical variables are presented as the absolute value (n) and percentage (%). bivariate and multiple variable logistic regressions were fitted. binary logistic regression requires the dependent variable to be dichotomous (e.g., yes vs no) and observations to be independent (worster et al., 2007). logistic regression is the appropriate regression analysis to conduct when the dependent variable is categorical (peng et al., 2002). as a predictive analysis, it describes data and explains the relationship between one dependent binary variable and independent variables. in our case, our dependent variable is ‘willingness to pay’, a categorical variable coded as yes= '1' and no= '0'. the independent variables included: socio-demographic and economic factors, healthrelated factors, perception, and knowledge. variables whose p-values are ≤ 0.2 during the bivariate analysis were fitted to the final multiple logistic regression model (backward step-wise) to adjust for potential confounders. in the final model, a p-value<0.05 was considered statistically significant. 2.5. ethics approval and consent to participate ethical clearance was obtained from the tigray regional health bureau. permission was sought from each selected district health office. informed oral consent was obtained from respondents as the majority of them were unable to read and write. enumerators explained the study objective to all participants. all the information obtained from the respondents was treated as private and confidential. 3. results 3.1. socio-demographic and economic characteristics of respondents a total of 823 individuals were enrolled in the study. four hundred and twenty (51%) were from setit-humera and 403(49%) were from wukro town. females comprised 449 (54.6%) and the goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 52 issn: 2220-184x majority, 757(92%) were orthodox christian. the average family size in the household was 4.2. the mean age of respondents was 39.6 years (sd±13.2 years). a quarter of the participants, 209 (25.6%), were in the age range of 18-29 years and 245 (30%) were in 30-39 years. more than half of the participants were married 476 (57.8%). five hundred seventy-three (69.7%) were illiterate (table 1). table1. socio-demographic characteristics of respondents in 2016. variable category frequency percent sex female 449 54.6 male 374 45.4 age 18-29 209 25.5 30-39 245 30.0 40-49 184 22.5 ≥50 180 22.0 marital status married 476 57.8 single 115 14.0 divorced 151 18.4 widowed 81 9.8 religion orthodox 757 92.0 muslim 61 7.4 catholic 2 0.2 protestant 3 0.4 educational status illiterate 573 69.7 literate 250 30.3 district wukro 420 51.0 setit-humera 403 49.0 house ownership owner 371 45.7 rented 414 51.1 dependent 26 3.2 one out of ten participants had no work at the time of data collection and 43.6% are engaged in sales and services. more than half (58.3%) of the respondents knew their family monthly income, and the median monthly income was 66.7 usd (interquartile range (iqr) = 72.2 usd). likewise, only 31% were a member of a local saving organization (idir), of which 228 (27.7%) respondents saved a median of 6.7 usd (iqr=5.2 usd) per year (table 2). goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 53 issn: 2220-184x 3.2. health-related characteristics of respondents of the total, 113 (13.7%) had a family member with a chronic illness. neuromuscular disorder (23.3%), kidney disease (21.4%), and tuberculosis (17.5%) were the most common diseases mentioned by heads of households. a hospital was the commonest (72.4%) place of care for people with chronic illness (table 3). among 395 (48.2%) respondents, at least one of their family members had an illness in the year 2016 (table 3). table 2. socioeconomic characteristics of respondents in 2016. variable category frequency percent occupation sales and services 354 43.6 unskilled manual 177 21.8 other 169 20.8 no work/unemployed 72 8.9 skilled manual 21 2.6 professional/technical/managerial 19 2.3 know monthly income no 332 41.7 yes 465 58.3 family monthly income ≤ 38.9 usd 119 25.6 39.0 – 66.7usd 120 25.9 66.8 – 111.1 usd 108 23.3 ≥111.2 usd 117 25.2 member of a local saving organization (idir) no 509 69.0 yes 228 31.0 amount of money saved per year ≤ 3.3 usd 84 38.1 3.4-6.7 usd 77 35.0 6.8-8.5 usd 3 1.4 ≥8.6 usd 56 25.5 note: 1usd = 18 et birr at the time of data collection table 3. health-related characteristics of respondents in 2016. variable category frequency percent presence of a family member with chronic illness no 710 86.3 yes 113 13.7 type of chronic illness (n=103) neuromamuscular disorders 24 23.3 kidney disease 22 21.4 tuberculosis 18 17.5 mental illness 14 13.6 asthma 7 6.8 goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 54 issn: 2220-184x cardiovascular disease 7 6.8 diabetic 6 5.8 hiv 4 3.8 cervical cancer 1 1.0 place of care for chronic illness hospital 76 72.4 health center 8 7.6 private facility 19 18.1 other 2 1.9 paid for medical care of chronic illness no 48 41.0 yes 69 58.1 illness in family member in 2016 no 425 51.8 yes 395 48.2 medical care sought at nowhere 2 0.3 hospital 282 41.2 health center 99 14.5 private facility 67 9.8 hc and hospital 96 14.0 hospital & private facility 79 11.5 hc & private facility 9 1.3 all the above 50 7.4 cost of care covered by self 620 89.9 waived 70 10.1 perceived affordability no 243 39.7 yes 369 60.3 note: hc= health center. table 4. descriptive result of selected scale variables among respondents in 2016. scale variables median (usd) interquartile range monthly income 66.7 72.2 saved money in idir 6.67 5.2 cost of medical care 11.1 28.9 wtp premium in wukro 7.8 5.5 wtp premium in humera 16.7 16.7 wtp premium (total) 11.1 15.6 note: wtp= willing to pay. as it is shown in table 4, the median amount of money paid for one medical care of chronic illness, as an oop expenditure, was 11.1 usd (iqr = 28.9). during the investigation of the cost of medical care for any illness (health problem) in the household, the median (iqr) cost for one goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 55 issn: 2220-184x medical care in public and private facilities was 5.6(5.3) and 22.2(22.2) usd, respectively. for respondents who used both facilities, the median (iqr) cost for one medical care was 16.7(29.4) usd. only 10 of the 305 (3.3%) respondents knew that the cost of care for their family was waived. seventy-nine (9.7%) had missed medical care due to a lack of money. 3.3. willingness to pay for health insurance in combination, the overall proportion of willingness to pay for cbhi in the two towns was 93.4% with a 95% ci (91.6-95.0). in setit-humera, 97.8% of the household heads were willing to pay for community-based health insurance, and in wukro, the willingness to pay was 89.3%. little variation was observed among men and women: 94.4% vs 92.7%, respectively. among the willing individuals, 65.2 % of them want to pay annually and 34.8% want to pay twice a year (table 5). the median amount of money participants can pay for the cbhi was 11.1 usd (iqr=15.6 usd). there was a significant difference in the median wtp money (p-value≤0.001) between the districts. respondents would like to pay a similar amount of money if the government decided it. table 5. willingness and amount of money individual households can pay per annum in 2016. variable category frequency percentage willing to pay no 54 6.6 yes 769 93.4 amount of money an individual is wtp ≤6.7 usd 188 22.8 6.8-11.1 usd 210 25.5 11.2-22.2 usd 174 21.1 ≥22.3 usd 143 17.4 did not mention 54 6.6 frequency preferred to pay annual 497 65.2 biannual 265 34.8 figure 1. source of information about community-based health insurance for participants in 2016. goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 56 issn: 2220-184x more than half, 57.6% (469/814), of the respondents heard about health insurance. the main sources of information were radio/television (54.7%) and friends (11.2%) (fig 1). 3.4. correlates of willingness to pay for community-based health insurance in multivariable logistic regression perceived affordability and knowledge of monthly income had statistically increased willingness to pay for community-based health insurance (table 6). table 6. factors associated with willingness to pay for health insurance in 2016. variables willing to pay cor (95% ci) aor (95% ci) yes no sex female 416 33 0.7 (0.3, 1.3) 0.5 (0.2,1.4) male 353 21 1 1 district wukro 375 45 1 1 setit-humera 394 9 5.3 (2.5, 10.9) * (1.8,0.5,6.2) perceived affordability no 226 17 1 1 yes 360 9 3 (1.3, 6.9) * 2.6(1.02,7.1) * know monthly income no 304 28 1 1 yes 449 16 2.6 (1.4,4.9) * 2.1(1.1,8.1) * illness of a family member no 391 34 1 1 yes 375 20 1.6 (0.9-2.9) 1.2 (0.4,3.3) heard about health insurance no 318 27 1 1 yes 446 23 1.6 (0.9-2.9) 2.7(0.9,8.6) note: *significant at p<0.05; cor-crude odds ratio; aor adjusted odds ratio. 4. discussion lack of health insurance in developing countries impedes access to health care. thus, cbhi has been considered an effective means to reach the poor (donfouet, 2012). since there has been an increased desire to extend the scheme, we investigated the willingness to pay among the urban community in northern ethiopia. this study showed that more than 90% of households in the two urban districts were willing to pay for community-based health insurance. this is higher than the proportion (52.4%) reported earlier by the ethiopian health insurance agency in the country (ethiopian health insurance agency, 2014) and other african countries (kimani et al.,2012; ina et al., 2016). but it was in line goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 57 issn: 2220-184x with a study conducted in bangladesh, where wtp for a cbhi scheme was 86.7% among informal workers (ahmed et al., 2016). this could be linked to a difference in the study population. in our study, we examined willingness in the urban community, while others focused on either rural or both setups. not only the decision to be enrolled but also the amount of money wtp for the scheme is very important. in the present study, the median amount of money household wtp was 11 usd. this amount is lower than the wtp in other african countries: cameroon and tanzania (donfouet et al., 2011; macha et al., 2014). across the countries, variations in socioeconomic status may be the likely explanation. in nigeria, the mean wtp per person per annum was 11.24 us dollars for urban households, which is in agreement with our findings. however, there is a difference in membership. in ethiopia, enrollment is allowed only at the household level (mebratie 2015) whereas in nigeria the membership decision is taken at an individual level (bukola, 2013). about 40% of the respondents had never heard about health insurance, although cbhi has been in operation in twenty rural districts in tigray (ethiopian health insurance agency, 2016). in support of this, obse et al. (2015) also reported that most participants of the fgds in addis ababa were not aware of the availability of health insurance. even, there is very limited knowledge among those who are currently insured. several studies have reported that affordability of premiums, low socioeconomic status, and poor quality of healthcare services offered to members, and limited referral services are major constraints to health insurance enrolment (onwujekwe et al., 2010; carrin et al., 2005; bonus, 2003; kamuzora et al., 2007). in our study, perceived affordability plays a crucial role in wtp for cbhi. the likely hood (odds) of willingness was four times higher among heads of households who perceive the cost of medical care is affordable. people who can afford to use health services frequently when they get sick. therefore, the scheme requires regular use of orthodox means of treatment (donfouet et al., 2011). in the current study, knowing monthly income was significantly associated with willingness to pay for health insurance, as knowledgeable household heads were two times more likely to be enrolled in the scheme. when people know their income, they might have saved money and planned expenses. in our setting, 65% of the respondents desired to pay annually. other studies showed that households do have enough willingness to pay if the payment mode is planned, conducive, and once per year (entele et al., 2016). goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 58 issn: 2220-184x in this study, income had no relation with wtp for the cbhi scheme. on the contrary, many studies such as onwujekwe et al. (2010); oyibo et al. (2015); entele et al. (2016); bärnighausen et al. (2007) revealed a positive correlation between wtp and income. in senegal, although community-based health insurance scheme reaches the poor in general, the poorest of the poor within the villages find it financially difficult to participate in the insurance (jutting, 2003). thus, social inclusion, a primary objective of the cbhi scheme, should not be overlooked. regarding the policy implications, the very high willingness-to-pay and the small differences in willingness-to-pay between the household head categories in table 5 seem to indicate that extending health insurance coverage is much needed in these two urban communities. 5. conclusion the study has shown a high level of willingness to pay for community health among household heads in an urban setting. the median amount of money wtp was 11 usd, and 65% of them want to pay annually. the mean willingness to pay money was significantly higher in setit-humera than in wukro. nearly half of the households had never heard of community-based health insurance. perceived affordability and knowledge of monthly income were significant factors that affect willingness to pay for community-based health insurance. the limitation of the study is that it was not triangulated by a qualitative study. social desirability bias might occur. respondents may not tell their exact monthly income. 6. recommendation we recommend intensive public awareness creation, and sensitization activities focusing on the benefits of health insurance before implementation. this is because there is limited knowledge about cbhi in the community. premiums must be set very carefully. it must take into account the willingness and ability to pay for the community. the government should introduce a premium subsidy for the poor as households who can't afford the cost of medical care were less willing to pay for this proposed scheme. 7. acknowledgments we would like to thank the tigray national regional state bureau of health and the ethiopian health insurance agency, mekelle branch for providing us with financial support. the authors are goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle university 59 issn: 2220-184x grateful to all of the district health office staff, the corresponding low-level administrators, and managers in the study area. finally, we would like to appreciate the study participants for their willingness and participation in the study. we sincerely thank both the reviewers for their helpful comments and the editors of the present journal for allowing us to publish the article in the prestigious journal. 8. conflict of interest there is no conflict of interest. 9. reference ahmed, s., hoque, m. e., sarker, a. r., sultana, m., islam, z., gazi, r., khan, j. a. m & lane, j. 2016. willingness-to-pay for community-based health insurance among informal workers in urban bangladesh. plos one, 11(2): e0148211, doi:10.1371/journal.pone.0148211 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health research, 4(3): 98-106, doi: 10.12691/aj phr-4-3-4. ethiopian health insurance agency. 2014. annual report. addis ababa, ethiopia ethiopian health insurance agency. 2016. annual report mekelle branch, mekelle, ethiopia fmoh. 2011. a directive to provide legal backing for the piloting and promotion of cbhi.addis ababa: ministry of health, ethiopia. ina, k., sabine, m., uzaib, s., theresa, k & david, c. 2016. the development of communitybased health insurance in rwanda: experiences and lessons. ministry of health. kigali. technical report, 9p, https://www.researchgate.net/publication/305721478. jütting, j. 2003. health insurance for the poor; determinants of participation in community-based health insurance schemes in rural senegal. oecd development centre working papers, no. 204, 30p, https://doi.org/10.1787/006580410672. kamuzora, p & gilson, l. 2007. factors influencing implementation of the community health fund in tanzania. health policy plan, 22(2): 95-102. kimani, j. k., ettarh, r., kyobutung, i. c., mberu, b & muindi, k. 2012. determinants for participation in a public health insurance program among residents of urban slums in nairobi, kenya: results from a cross-sectional survey. bmc health services research, 12: 66, doi: 10.1186/1472-6963-12-66. macha, j., kuwawenaruwa, a., makawia, s., mtei, g & borghi, j. 2014. determinants of community health fund membership in tanzania: a mixed-methods analysis. bmc health services research, 14: 538, https://doi.org/10.1186/s12913-014-0538-9. mebratie, a. d. 2015. essay evaluating a community-based health insurance scheme in rural ethiopia. phd thesis, international institute of social studies, 256p, http://www.ipskampdrukkers.nl/. mailto:microinsurance@ilo.org https://www.researchgate.net/scientific-contributions/ina-kalisa-2242291710?_sg%5b0%5d=xxugbrdocovent5p7lr3uwqbkeyc5hfvgaroaefm4unbms8mjxfl01wkueg7skufiuxduoo.6o2f_iovxrby8p3s4yqupllnr9wcbfc2ui2dk4w7pydnvscenghpsm4y_qo-myx6eb8-x6kauw6prk5bnaksyq&_sg%5b1%5d=7swvfd_z7sj6rlabtbsb8dlwchjtk18dgu_gz8remk6lgelvaaddbadwun_au5isbn7hweg.bx4yaotufwe-cozukppczfna-gbtzoa9r6w_f1zncvngntvurp4z8ulyxftfua4pqqe0y_-jrrgrezrx4qg0pw https://www.researchgate.net/scientific-contributions/sabine-musange-2203345843?_sg%5b0%5d=xxugbrdocovent5p7lr3uwqbkeyc5hfvgaroaefm4unbms8mjxfl01wkueg7skufiuxduoo.6o2f_iovxrby8p3s4yqupllnr9wcbfc2ui2dk4w7pydnvscenghpsm4y_qo-myx6eb8-x6kauw6prk5bnaksyq&_sg%5b1%5d=7swvfd_z7sj6rlabtbsb8dlwchjtk18dgu_gz8remk6lgelvaaddbadwun_au5isbn7hweg.bx4yaotufwe-cozukppczfna-gbtzoa9r6w_f1zncvngntvurp4z8ulyxftfua4pqqe0y_-jrrgrezrx4qg0pw https://www.researchgate.net/profile/uzaib-saya-3?_sg%5b0%5d=xxugbrdocovent5p7lr3uwqbkeyc5hfvgaroaefm4unbms8mjxfl01wkueg7skufiuxduoo.6o2f_iovxrby8p3s4yqupllnr9wcbfc2ui2dk4w7pydnvscenghpsm4y_qo-myx6eb8-x6kauw6prk5bnaksyq&_sg%5b1%5d=7swvfd_z7sj6rlabtbsb8dlwchjtk18dgu_gz8remk6lgelvaaddbadwun_au5isbn7hweg.bx4yaotufwe-cozukppczfna-gbtzoa9r6w_f1zncvngntvurp4z8ulyxftfua4pqqe0y_-jrrgrezrx4qg0pw https://www.researchgate.net/profile/david-collins-35?_sg%5b0%5d=xxugbrdocovent5p7lr3uwqbkeyc5hfvgaroaefm4unbms8mjxfl01wkueg7skufiuxduoo.6o2f_iovxrby8p3s4yqupllnr9wcbfc2ui2dk4w7pydnvscenghpsm4y_qo-myx6eb8-x6kauw6prk5bnaksyq&_sg%5b1%5d=7swvfd_z7sj6rlabtbsb8dlwchjtk18dgu_gz8remk6lgelvaaddbadwun_au5isbn7hweg.bx4yaotufwe-cozukppczfna-gbtzoa9r6w_f1zncvngntvurp4z8ulyxftfua4pqqe0y_-jrrgrezrx4qg0pw https://www.researchgate.net/publication/305721478 https://doi.org/10.1787/006580410672 goitom, g., gebremedhin, b. g., estifanos, g., atakilti, a and berihu, m (mejs) volume 15(1):48-61, 2023 © cncs, mekelle 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https://www.who.int/gho/health_financing/out_of_pocket_spending/en/ http://data.worldbank.org/indicator/sh.xpd.oopc.zs https://doi.org/10.1017/s1481803500014883 403 forbidden forbidden you don't have permission to access this resource. apache/2.4.46 (ubuntu) server at www.ajol.info port 443 research article http://dx.doi.org/10.4314/mejs.v15i1.3 momona ethiopian journal of science (mejs), v15(1): 32-47, 2023 ©cncs, mekelle university, issn:2220-184x submitted on: 26th august 2018 revised and accepted on: 27th january 2023 synthesis, physicochemical, and antimicrobial activity of copper and zinc complexes with n, o bidentate schiff base elias assayehegn1*, abraha tadese1, goitom g/yohannes1, samuel alemayehu2 and tesfamariam teklu1 1 department of chemistry, college of natural and computational sciences, mekelle university, p. o. box 231, mekelle, ethiopia (*assaye98@gmail.com, abrishmu08@gmail.com, goitish2500@gmail.com, betynatan@gmail.com). 2 department of biology, college of natural and computational sciences, mekelle university, p. o. box 231, mekelle, ethiopia. abstract this paper is intended to prepare new antimicrobial complexes with proven efficiency. the schiff base, through the condensation process of salicylaldehyde and p-toludine, and its cu and zn complexes were successfully synthesized. the schiff base and its complexes were characterized using molar conductivity, ultraviolet-visible (uv-vis), atomic absorption spectroscopy (aas), and fourier transform infrared (ftir) techniques. accordingly, these characterizations not only confirmed that the synthesized schiff base acted as n,o bidentate ligand (through azomethine nitrogen and phenoxide oxygen) and chelated with cu(ii) and zn(ii) in the metal-to-ligand ratio of 1:2 but also revealed the characteristic electronic-transition of π→π*/n→π* of the ligand, and ligand-metal charge transfer and d-d of the metal complexes. moreover, both cu and zn complexes recorded weak molar conductance of 54.12 and 51.41 s cm2 mol-1, respectively. further, their antibacterial activities were evaluated by disc diffusion assay against staphylococcus aureus (gram-positive), escherichia coli (gram-negative), and bacillus cereus (gram-negative) bacteria. for all microbial, the metal complexes recorded higher activities than the parent ligand; such increased activity of the complexes may be due to the chelation of the metal ion in the complexes, which enhances the lipophylic character favoring its permeation through the lipid layer of the cell membrane. such metal complexes can therefore be explored in the future as an option for decreasing the pathogenic potential of infecting bacteria. keywords: metal complex, schiff base, condensation reaction, antimicrobial activity, salicylaldehyde. 1. introduction organometallic-composites, organic and inorganic hybrid systems, represent a class of advanced materials with novel properties for a wide range of applicationsbiomedicine, food, cosmetics, agriculture, paints, catalysis, and textiles (emam, 2019; nazirkar et al., 2019; saranya et al., 2020; sathiyavimal et al., 2018; vasantharaj et al., 2019). such materials encompassed transition metals and macro-organic molecules; notably, schiff bases have been well-known counterparts. schiff bases, imine compounds with azomethine (c=n) functional group, are typically formed by the condensation of a primary amine and an aldehyde or a ketone; the resultant compound has a mailto:assaye98@gmail.com mailto:abrishmu08@gmail.com mailto:goitish2500@gmail.com mailto:betynatan@gmail.com elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 33 issn: 2220-184x general formula of r1r2c=nr3, where r1 is an aryl group, r2 is a hydrogen atom, and r3 is either an alkyl or aryl group (abdulkarem et al., 2017; hossain et al., 2018; rehman et al., 2019). despite their synthetic problem, a wide variety of ligands that vary in denticity, flexibility, nature of donor atoms, and electronic properties can be tuned. particularly, chelating ligands containing n, s, and o donor atoms are regarded as privileged ligands due to their ability to form stable complexes with a wide range of transition metals (cipurković et al., 2021; fasina et al., 2012; frei 2020; mehmet tuèmer et al., 1999; saranya et al., 2020; zhao et al., 2015). notably, schiff bases and their complexes are reported to possess a broad range of important biological activity like antimicrobial, antibacterial, antifungal, anticancer, anti-flammatory agents, anti-hiv, antimalarial, antiproliferative, antipyretic properties, anti-depressant and diuretic activities (lakshmanan et al., 2018; revathi and thambidurai, 2017; shiekh et al., 2013). for instance, a series of 1-(5-substituted-2-oxoindolin-3-ylidene)-4-(substituted-pyridin2-yl) thiosemicarbazide derivatives were screened and evaluated for in-vitro antibacterial and antifungal activity against b. subtilis, s. aureus, e. coli, p. aeruginosa, c. albicans, and a. niger; they were exhibited a moderate to antibacterial/fungal activities (arulmurugan et al., 2010). similarly, it is revealed that the me2dibenzo[b,l]dipyridyl[g,q][1,5,11,15]-tetraaza-6,10,16,20tetraoxocycloeicosane macro-cyclic complexes of mn(ii) and co(ii) have demonstrated antibacterial activities against e. coli, p. aeruginosa, b. cereus, s. aureus, and antifungal against c. albicans (kumar et al., 2015). meanwhile, antimicrobial resistance is alarmingly becoming a global concern with rapid increment in multidrug-resistant microbial. with the help of specific drug treatment, most diseases are cured; however, these days, some pathogens are uncured since they developed resistance to the specific treatment. for instance, staphylococcus aureus, and enterococcus became resistant to methicillin, and vancomycin antibiotic drugs, respectively (rafique et al., 2010; siddappa et al., 2014; srivastava et al., 2010; zhang and lippard, 2003). furthermore, this drug-resistance microbial class comprises enterococcus faecalis, m. tuberculosis, escherichia coli, shigella flexeneri, pseudomonas aeruginosa, salmonella typhi, and bacillus subtilis. even some fungal pathogens showed resistance features against candida albicans, aspergillus flavus, fusarium solani, and candida glaberata drugs (saha et al., 2009). consequently, there is an urgency to develop new and more effective drugs with low toxicity; otherwise, they will emerge elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 34 issn: 2220-184x as one of the most dangerous threats to the successful treatment of microbial/insecticidal diseases and human well-being. the aim of this paper, therefore, was to prepare new antimicrobial complexes with proven efficiencyincluding synthesizing and characterizing cu(ii) and zn(ii) metal complexes of schiff base derived from the condensation of salicylaldehyde with p-toludine. furthermore, investigating their antimicrobial activities against staphylococcus aureus, escherichia coli, and bacillus cereus by using the disc diffusion method was the other motive. 2. experimental design 2.1. chemicals important chemicals such as p-toludine (95%, sigma aldrich, usa), salicylildehyde (95%, sigma aldrich, usa), zncl2.6h2o (98%, sigma aldrich, usa), cucl2.2h2o (98%, sigma aldrich, usa), koh (fluka, switzerland), ethanol (nice, india), ether (finkem, india), acetone (loba, india), hcl (fluka, switzerland), h2so4 (fluka, switzerland) and dimethylsulphoxide (dmso, finkem, india) were purchased; all the chemicals were analytical grade and used without further purification. similarly, nutrient agar medium, mueller-hinton agar medium, inoculating wire loop, sterilized 6 mm paper discs, antibiotic zone scale, and ampicillin were deployed. the microorganisms for checking the antimicrobial activities were staphylococcus aureus (gram-positive), escherichia coli, and bacillus cereus (gram-negative), which were verified and donated from the microbiology division of mekelle university. 2.2. physical measurements melting points of the ligands and their metal complexes were determined by an open capillary method using electro-thermal melting point apparatus. similarly, their conductance measurements were carried out using an elico conductivity bridge and dip-type conductivity cell. notably, their elemental analyses and ftir spectra were recorded with an elemental vario el iii model and a perkin elmer spectrum bx ft-ir spectrophotometer (usa) as kbr pellets in the range of 4,000-400 cm–1, respectively. the electronic transition of the ligand and metal complexes were studied using a spectronic genesys 2pc uv-vis spectrophotometer (usa) in the range of 200-750nm. elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 35 issn: 2220-184x 2.3. syntheses methods 2.3.1. syntheses of schiff base the schiff base was synthesized by a modified procedure (khaled et al., 2013); specifically, 10 mmol of salicylaldehyde and 0.5 mol of ethanol were put in a 250-ml round bottom flask while stirring for 5 min in a hot water bath. to this mixture, 10 mmol of p-toludine was added and stirred for 10 min. then, it was transferred to a reflux setup and refluxed in a hot water bath (8090 oc) for 4 h after adding 0.5 mmol of conc. hcl. subsequently, the product was filtered and washed with cold ethanol, acetone, and ether. finally, it was recrystallized from ethanol. 2.3.2. syntheses of metal complexes the cu(ii) and zn(ii) complexes were prepared via a modified procedure (aiyelabola et al., 2012; khaled et al., 2013); typically, 2 mmol of the as-prepared schiff base and 0.5 mol of ethanol were put in the bottom flask while stirring in hot water-bath for 5 min. to this mixture, 1 mmol of zncl2.6h2o was added and stirred for 20 min. next, the as-obtained mixture was refluxed in a water bath (80-90 °c) for 5 h with stirring after adding 0.4 mmol naoh solution step-wise. then, the zn complex was filtered and washed thoroughly with water, ethanol, ether, and acetone. finally, it was dried in a desiccator. the same procedure was followed for preparing the cu complex except for replacing zncl2.6h2o with cucl2.2h2o. 2.4. evaluation of antimicrobial activity nutrient broth (peptone, 10; yeast extract, 5; nacl, 10 in (g/l)) was used for culturing of staphylococcus aureus, escherichia coli, and bacillus cereus; 10% dmso solution was used as a solvent. the media and glassware were autoclaved for 15 min at 121°c under 15 psi pressure. after cooling, a loop of each bacteria strain was inoculated in 50 ml autoclaved media and incubated at 37 °c for 24 h. then, 100 μl of the culture was uniformly plated on petri plates using a sterile rod. a sterilized circular paper disk (of 6 mm diameter) was placed in the center of petri plates in contact with the culture, and schiff base and complexes were pipetted onto it (khaled et al., 2013; shiekh et al., 2013). the concentration of schiff base and the complexes were varied at 500 μg/ml, 800 μg/ml, and 1 mg/ml. ampicillin was used as a standard drug. after 24 h of incubation at 37 °c, all plates were examined for possible inhibition zone in millimeters (mm). elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 36 issn: 2220-184x 3. results and discussion 3.1. the physical and chemical properties the schiff base, the ligand, was prepared through a condensation reaction of the carbonyl group of the salicylaldehyde and the –nh2 group of the toludine (scheme 1) with a 47% yield. since the reaction is slow and reversible, in favor of the forward reaction, hcl was added as a catalyst. while the complexes of cu(ii) and zn(ii) were prepared using metal-to-ligand in a 1:2 mole ratio; the ph of the reaction was adjusted by adding aqueous naoh. the presence of the base, naoh, enhances the nucleophilicity of the ligand and affords uni-negative chelation with metal ions (khaled et al., 2013), which boosts % yield of cu and zn complexes with 60% and 67% yield, respectively (table 1). form the series of solubility tests, it was found that the ligand is readily soluble in benzene; sparingly soluble in methanol, ethanol, and acetonitrile; but partially soluble in chloroform and petroleum ether. ch o oh h2n och3 salicylaldehyde p-toludine ref. 4hr 2ml hcl c oh h2o ligand scheme 1. formation of new schiff base n och3 h however, the cu and zn complexes are readily soluble in dmso and dmf; hardly soluble in ethanol, methanol, or chloroform; and insoluble in benzene. meanwhile, both the ligand and its cu/zn complexes decomposed above 280 and 350 °c, respectively (table 1) without showing melting point, which was similarly reported elsewhere (ahamad et al., 2012). chemically, the ligand and its complexes are stable in the atmosphere, revealing they are nonhygroscopic. however, the former is found sensitive to water; it hydrolyses to respective parent compounds. on the other hand, the ligand shows only a single spot on the tlc test, which indicates it is pure. contrarily, since the complexes are insoluble in most common solvents, they had not been tested. meanwhile, using volhard’s test, the chloride test for cu(ii) and zn(ii) complexes was found negative, indicating there is no chlorine ion either in the inner or outer sphere of the complexes (rama and selvameena, 2014). elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 37 issn: 2220-184x table 1. physical properties of the schiff base and its metal complexes. molecular formula molecular weight (g/mol) physical appearance color decompose (oc) yield (%) average inhibition zone (mm) l(c14h13o2n) 227.26 fine powder greenishyellow > 280 °c 47 2.56 cul2(h2o)4 ([cu(c14h12o2n)2(h2o)2].2h2o) 588.12 fine powder dark brown > 350 °c 60 7.91 znl2(h2o)2 ([zn(c14h12o2n)2(h2o)2]) 553.93 fine powder white > 350 °c 67 7.49 molar conductance was determined from conductivity measurement of the complexes in dmso at 24 °c using the relation λm= 10 3 l/c, where λm is the molar conductance of the complexes, l is the specific conductance, and c is the molar concentration of the metal complex solutions (mohamed et al., 2014). accordingly, the molar conductances of the cu and zn complexes were found to be 54.12 and 51.41 s cm2 mol-1, respectively, indicating their nonelectrolyte nature (mahal et al., 2015). moreover, rendering to the elemental analysis, it is noted that the experimental cu metal percentage is 9.47% which is close to the calculated value of 10.81% for the formula cul2(h2o)2.2h2o. similarly, the recorded experimental zn metal percentage of 10.96 % is close to the calculated value of 11.80% for the formula znl2(h2o)2. thus, the metal-to-ligand ratio is found to be 1:2 which is the same as the mole ratio used for the complex synthesis. figure 1. ftir spectrum of the ligand. elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 38 issn: 2220-184x 3.2.infrared spectra ftir is a powerful technique for determining the functional groups of the targeted molecule. the ftir spectrum of the ligand displays the characteristic vibration frequencies (fig 1) and reveals that the targeted schiff base has been synthesized. the broad band centered at 3435 cm-1 is inferred to be phenolic o-h with its intra/intermolecular hydrogen bonding around 3600 cm-1 (ali et al., 2018; cao et al., 2019). the strong sharp band located at 1617 cm-1 is attributed to the c=n stretching of the azomethine group; along with the absence of carbonyl bond (c=o) and amine (n–h), vibrations around 1744 and 1587 cm-1, respectively, it strongly confirms that the condensation reaction took place, leading to the formation of azomethine group (azamia et al., 2017; jia et al., 2021; revathi and thambidurai, 2017). figure 2. ftir spectra of cu (a) and zn complex (b). whereas, the c=c stretching of the aromatic ring is observed at 1488 cm-1. notably, the n-o stretching, around 1449 cm-1, is not reordered, indicating no oxidized nitrogen groups elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 39 issn: 2220-184x (azamia et al., 2017). the other strong band at 1255 cm-1 could be assigned to c-o stretching of the phenolic/methoxy group while the bands at 1149, 750, and 729 cm-1 correspond to the bending frequencies of o-h phenolic, c-h of the methoxy, and aromatic ring of the ligand, respectively (foorginezhad and zerafat, 2018; zhou et al., 2020). meanwhile, comparing the spectrum of the ligand with its cu(ii) and zn(ii) complexes, a significant shift of characteristics bands can be observed that reveals the complexation has occurred (fig 2). the band centered at 3422 and 3113 cm-1 can be assigned to the o-h stretching of the coordinated water in cu(ii) and zn(ii) complexes, of cul2(h2o)2.2h2o and znl2(h2o)2 formula; and its coordinated water molecule exhibits rocking, twisting and waging modes in the lower frequency region ranging from 1000-700 cm-1 (mohamed et al., 2014). like the ligand, the bands in the range of 2950-2360 cm-1 can be assigned to the c-h stretching of aromatic/methoxy groups of the complexes (chauhan et al., 2019). the characteristic stretching band of the c=n group in the free ligand, which was 1617 cm-1, is shifted to a lower frequency to 1590 and 1581 cm-1 in the cu(ii) and zn(ii) complexes, respectively (mahal et al., 2015). consequently, this negative shift in frequency of the c=n band of the free ligand deduces the involvement of the nitrogen atom of the azomethine group in complexation (cipurković et al., 2021; mahal et al., 2015; rama and selvameena, 2014). not only this, the positive shift of c-o stretching to 1261 in cu(ii) and 1258 cm-1 in zn(ii) indicates the deprotonation of the phenolic group, which was 1149 cm-1 in the ligand. subsequently, this happened when the oxygen atom of the phenoxide is attached to metal in the complex (akila et al., 2012; nazirkar et al., 2019). furthermore, another fingerprint of the metal complex has been disclosed in the less than 1000 cm-1 vibration frequency; the bands at 698 and 602 cm-1 in cu(ii), and 668 and 585 cm-1 in zn(ii) can be assigned for m–o, and m–n stretching, respectively (cipurković et al., 2021; el-yazeed and ahmed, 2019; ghobashy, 2017; mahal et al., 2015). therefore, the ftir analysis confirms that the ligand behaves as an n,o-bidentate in both complexes, coordinating via the nitrogen of the azomethine and oxygen of the phenoxide. the main characteristics of stretching bands for the schiff base and complexes of cu and zn are summarized in table 2. table 2. ftir spectral data of the ligand and its cu and zn complexes. samples υc=n (cm-1) υo-h (cm-1) υc-o (cm-1) υc-h (cm-1) υm-n (cm-1) υm-o (cm-1) ligand 1617 3550-2950 1255 3050 elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 40 issn: 2220-184x cu-l2 complex 1590 3530-2900 1261 2950 602 698 zn-l2 complex 1581 3400-2900 1258 2359 585 668 3.3.uv-vis spectra of the ligand and metal complexes uv-vis technique determines how the electron transition between the ligand moieties and the metal ion is. the uv-vis spectra of the ligand and complexes are presented (fig 3). according to, the ligand displays high-intensity bands at 28,248 cm-1 (354 nm) with a shoulder absorption of 27,472 (364 nm) which is fairly assigned to a combination of π→π* and n→π* transition characteristic of the azomethine chromophore, respectively. this once again confirms the successful preparation of the ligand with the c=n functional group. figure 3. uv-vis spectra of ligand (a) and cu(ii) complex (b). furthermore, the strong absorption at 33,333 cm-1 (300 nm) with weak multiple bands in the range of 42,553-36,231 cm-1 (235-276 nm) indicates n→π* transitions of the substituted benzene moieties and the aromatic group, respectively (mahal et al., 2015; mohamed et al., 2014; rama and selvameena, 2014). meanwhile, the electronic spectra of cu(ii) and zn(ii) complexes display important new prominent bands; for cu(ii) complex, high-intensity bands at 31,250 cm-1 (320 nm), and 24,875 cm-1 (402 nm) with a shoulder of 21,978 cm-1 (455 nm) are observed (fig 3b), inferring the charge transfer between the phenolic and azomethine chromophores of the ligand with cu metal, respectively. compared with free ligands, this is because of a bathochromic shift in the absorption frequencies of phenolic and azomethine chromophores, as the result of their involvement in complexation (amane et al., 2014; mahal et al., 2015). this reconfirms the coordination through phenolic oxygen and azomethine nitrogen elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 41 issn: 2220-184x with cu(ii). similarly, for the zn complex, the phenolic and azomethine bathochromic shift are spotted at 30,769 cm-1 (325 nm), and 24,096 cm-1 (415 nm). furthermore, the broad band centered at 14492 cm-1, (690 nm) for cu(ii) could be assigned to the combination of three possible transitions 2b1→ 2a1, 2b1→ 2b2, and 2b1→ 2e which strongly suggests a distorted octahedral geometry around cu(ii) (shiekh et al., 2013). moreover, the zn(ii) complex shows no d-d band absorption, because of its electronic configuration, d10 (amane et al., 2018; mohamed et al., 2014). 3.4. biological activity in assessing their potential antimicrobial agents, the antibacterial activity, in-vitro, of the ligand and its complexes at the concentration of 500 μg/ml, 800 μg/ml, and 1 mg/ml were tested against gram-positive staphylococcus aureus, gram-negative escherichia coli, and bacillus cereus bacteria while comparing with ampicillin, a control antibacterial drug. the antimicrobial result is displayed in figure 4. figure 4. the average microbial activity of as-prepared ligand (l), cu complex (cul2), zn complex (znl2), and ampicillin (a) against all bacteria (a), against staphylococcus aureus (b), escherichia coli (c), and bacillus cereus (d) bacteria at the concentration range of 500 μg/ml (blue color), 800 μg/ml (red) and 1 mg/ml(green). elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 42 issn: 2220-184x it can be seen that both cu(ii) and zn(ii) complexes demonstrate the higher biological activity with an average inhibition zone of 7.9 and 7.5 mm than the ligand (2.6 mm) against the three bacteria (fig 4a). this could reveal that coordinating metals within the ligand enhance the biological activity of the ligand as reported and reviewed elsewhere too (amane et al., 2014; prakash and adhikari, 2011; tobriya, 2014). such chelation enhances the lipophylic character favoring its permeation through the lipid membrane so which increases the activity of the metal complexes (shiekh et al., 2013) the specific performance of as-prepared powders against each staphylococcus aureus, escherichia coli, and bacillus cereus are displayed (fig 4b-d); evidently, it does not only indicate the fair performance comparing with ampicillin but also increment of activity as the function of their concentration. notably, all the samples record their highest performance at 1 mg/ml. the current observation may serve as a guide for studying the controlled release of these complexes which could be a promising future. 4. conclusion the schiff base and its cu(ii), and zn(ii) complexes were successfully synthesized via condensation of salicylaldehyde and toluidine, and a common reflux method, respectively. the ligand acts as n, o-bidentate through the coordination of azomethine nitrogen and oxygen of the phenoxide. further, their antibacterial activities were evaluated by disc diffusion assay against gram-positive staphylococcus aureus, gram-negative escherichia coli, and bacillus cereus bacteria. both cu(ii) and zn(ii) complexes displayed higher biological activity with an average inhibition zone of 7.9 and 7.5 mm than the ligand (2.6 mm) against the three bacteria; this performance is enhanced with the function of their concentration. in this regard, this study revealed that the metal complexes demonstrated higher activities than that of the parent ligand. such increased activity of the metal complexes may be due to the chelation of the metal ion, which enhances the lipophylic character favoring its permeation through the lipid layer of the membrane. to the extent that our results are concerned, these metal complexes can therefore be explored in the future as an option for decreasing the pathogenic potential of infecting bacteria. 5. acknowledgments the authors are grateful to mekelle university for the financial support of this research (registration no. cncs/rb54/2013), and to the reviewers for their constructive comments. elias, a., abraha, t., goitom, g., samuel, a and tesfamariam, t (mejs) volume 15(1):32-47, 2023 © cncs, mekelle university 43 issn: 2220-184x 6. conflict of interest no conflict of interest. 7. reference abdulkarem, a. a. 2017. synthesis and antibacterial studies of metal complexes of cu (ii), ni (ii) and co (ii) with tetradentate ligand. journal of biophyical chemistry, 8: 13–21, doi:10.4236/jbpc.2017.82002. ahamad, m., rao, r.m., rafi, m., mohiddin, g.j & sreeramulu, j. 2012. synthesis, spectral analysis and antimicrobial activity of novel dithiocarbamate schiff base metal complexes. archives of applied science research, 4(2): 858-862. aiyelabola, t.o., ojo, i.a., adebajo, a.c., ogunlusi, g.o., oyetunji, o & akinkunmi, e,o. 2012. synthesis, characterization and antimicrobial activities of some metal (ii) amino acids’ complexes. advances in biological chemisty, 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international journal of science and research, 3(9): 2012–4. vasantharaj, s., sathiyavimal, s., senthilkumar, p., lewisoscar, f & pugazhendhi, a. 2019. biosynthesis of iron oxide nanoparticles using leaf extract of ruellia tuberosa: antimicrobial properties and their applications in photocatalytic degradation. journal of photochemistry and photobiology b: biology, 192: 74–82. zhang, c.x & lippard, s.j. 2003. new metal complexes as potential therapeutics. current opinion in chemical biology, 7(4): 481-489. zhao, x., xue, l & zhang, c. 2015. schiff base copper(ii) and zinc(ii) complexes: synthesis, structures, and antimicrobial activities. synthesis and reactivity in inorganic, metalorganic, and nano-metal chemistry, 45(4): 516-520, doi: 10.1080/15533174.2013.841216. zhou, q., rather, l.j., ali, a., wang, w., zhang, y, haque, q.m.r & li, q. 2020. environmental friendly bioactive finishing of wool textiles using the tannin-rich extracts of chinese tallow (sapium sebiferum l.) waste/fallen leaves. dyes and pigments, 176: 108230, doi.10.1016/j.dyepig.2020.108230. quality assessment of the commonly prescribed antimicrobial drug, ciprofloxacin tablets, marketed in tigray, ethiopia getu kahsay1* and awot g/egziabher2 1* department of pharmaceutical chemistry, school of pharmacy, college of health sciences, mekelle university, p.o.box 1871, mekelle, ethiopia (*getu_kah@yahoo.com) 2 drug quality control and toxicology laboratory, ethiopian drug administration and control authority, p.o.box 5681, addis ababa, ethiopia abstract an attempt was made to assess the quality and compare the physicochemical equivalence of six brands of ciprofloxacin tablets marketed in tigray, ethiopia. six brands of ciprofloxacin tablets were used in the study. identity, weight uniformity test, disintegration test, dissolution test and assay for the content of active ingredients were performed using the methods described in the british pharmacopoeia. all the samples passed the identity, disintegration, and dissolution tests but ciflox failed to release 80% of the drug content within 30 minutes as stipulated in the pharmacopoeia. this product therefore does not comply with the bp 2004 dissolution tolerance limits. all of the brands examined pass the assay for content of active ingredient. this work revealed that the six brands included in the study complied with the physicochemical quality parameters except ciflox which failed to meet the pharmacopoeial specification for dissolution test. nevertheless the six brands showed that there is significant difference in the drug release in vitro (p<0.05). to justify the specification limits of the in vitro dissolution test, an attempt should be made to establish a meaningful correlation between in vitro release characteristics and in vivo bioavailability parameters. keywords: physicochemical properties; quality; bioequivalence; dissolution rate; hplc. 1. introduction the safety and efficacy of drug products can be guaranteed when their quality is reliable and reproducible from batch to batch. to ensure the requisite quality, drug manufacturers are required to test their products during and after manufacturing and at various intervals during the shelf life of the product (chow, 1997). the quality of medicines is an integral part of access in light of ensuring that the pharmaceutical products are fit for their intended use, comply with the requirement of the marketing authorization and do not expose consumers to risks. to attain this objective there must be a system of quality assurance, which incorporates aspects including product development, manufacture, distribution, and storage. many developing countries do not have an effective means of monitoring the quality of generic drug products in the market. this results in widespread distribution of substandard and/or counterfeit drug products. it was in view of this fact that the world health organization (who) issued guidelines for global standard and © cncs mekelle university getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 requirements for the registration, assessment, marketing, authorization, and quality control of generic pharmaceutical products (who, 1996; who, 2005). the combination of market forces, the low per capita spending on pharmaceuticals by most of the population and the lack of adequate resources for controlling and monitoring the quality of drugs on the market creates an environment favorable for introducing low quality drugs in developing countries. until very recently, the focus of developing country health advocates has been getting drugs into the supply chain at affordable prices. the quality of these drugs and the threat of counterfeit pharmaceuticals have been largely ignored. however, there is mounting evidence that counterfeit pharmaceuticals pose a serious threat to public health, especially in developing countries (pecoul et al., 1999; who, 2005). according to the united states food and drug administration (fda), bioavailability and bioequivalence of drug products, and drug product selection have emerged as critical issues in pharmacy and medicine during the last three decades. concern about lowering health care costs has resulted in a tremendous increase in the use of generic drug products; currently about one half of all prescriptions written are for drugs that can be substituted with a generic product (miller, 1990). in 1975, approximately 9% of all prescription drugs dispensed were generic versions. this percentage rose to 20% in 1984, and 40% in 1991. indeed substitution of generic drugs for brand name products is highly controversial and is often met with suspicion by health care providers and patients (covington, 1992; meredith, 2003). the fda has mandated that all generic drugs meet the same standards as the brand name drugs in strength, safety, purity and performance. however, there are substandard and/or counterfeit generic drugs that don’t satisfy the pharmacopoeial standards set for them. in several developing countries, drug quality is a source of concern. there is a general feeling that there is a high incidence of drug preparations, which are not of acceptable quality (ten ham, 1992). counterfeit pharmaceuticals comprise a significant and growing problem. pharmaceutical counterfeiting is a pervasive problem, impacting nations of every size and income level and drugs of every description (alubo, 1994; graciela, 2001). there are many reports of the availability of counterfeit medicines, not only in developing countries but also in europe and usa (shakoor et al., 1997). reports indicate that there are substandard drugs circulating in the market in different developing countries. marketing of such drugs has been widely reported in africa, asia, and latin america. © cncs mekelle university 94 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 in 2003, who reported that fake drugs reported between 1999 and 2002 include analgesics and antipyretics (6%), antimalarials (7%), anti-asthma and anti-allergy (8%), antibiotics (28%), hormones and steroids (18%) and other therapeutic categories (33%). thus, the aforementioned problems have resulted in a weak therapeutic efficiency, selection of resistance strains and poor quality of numerous drugs (menkes, 1997; newton et al., 2001; taylor et al., 2001). lack of competent regulatory authorities and poor quality control practices in some countries, have allowed the availability of poor quality drugs. these could be the widespread counterfeiting of medicines, decomposition of the active ingredient in drug dosage form due to high temperature and humidity of the storage condition, and inadequate quality assurance systems during the manufacture of pharmaceutical products (risha et al., 2003; kaymba et al., 2004; hebron et al., 2005). preliminary physicochemical assessment of drug products has a paramount importance in ensuring the quality of drug products. generic drug products must satisfy the same standards of quality, efficacy and safety as those applicable to the innovator products. in vitro dissolution testing can be a valuable predictor of the in vivo bioavailability and bioequivalence of oral solid dosage forms (itiola and pilpel, 1996). thus, the present study was carried out to evaluate the physicochemical quality and equivalence of six brands of ciprofloxacin tablets purchased from retail pharmacy outlets in mekelle using in vitro methods. the preliminary study was aimed at obtaining baseline data towards the establishment of bioequivalence of the tablets thereby rendering information for regulatory bodies as well as manufacturers to ensure the quality of these essential drug products through monitoring by post-marketing surveillance. 2. materials and methods 2.1 materials table 1 shows the detailed information on ciprofloxacin tablet formulations included in the study. the drugs were selected on the basis of being included in the ethiopian national drug list obtained from the ethiopian drug administration and control authority (daca). ciprofloxacin tablets were obtained from the retail outlets mainly from private pharmacies and drug stores in mekelle, tigray. the drug samples were anonymously purchased in their original package as supplied by the manufacturers and protected from direct sunlight. © cncs mekelle university 95 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 table 1. detailed information on ciprofloxacin 500 mg tablet formulations evaluated for quality. manufacturer brand name strengthbatch no mfg. date exp. date sunshine pharmaceuticals, ethiopia ciprofloxacin500 mg 07011201 jul-2004 jan-2009 kwang mayung pharma, korea floxine 500 mg 7008 mar-2007 mar-2010 addis pharmaceutical factory s.c, ethiopia ciflox 500 mg 2973 nov-2007 nov-2009 cadila pharmaceuticals ltd., india ciprodac 500 mg e6047 oct-2006 sep-2009 c.p.m contract pharma gmbh & co. kg, germany cipro-denk 500mg 1117 jul-2007 jul-2010 torrent pharmaceuticals ltd, india quintor 500 mg b3997017 feb-2007 jan-2011 2.1.1 instruments and equipment a high performance liquid chromatography (hplc), a pharma test dissolution tester, a uv/vis spectrophotometer, an ultrasonicator, an electronic micro balance, and a high performance thin layer chromatography (hptlc) aluminum sheets were used for the study. 2.1.2 chemicals and reagents the following chemicals and reagents were used in the study: acetonitrile and ammonia hplc grade, bdh (uk), dichloromethane, orthophosphoric acid, methanol and triethylamine, hplc grade, were obtained from sigma-aldrich (germany). water, double distilled and deionized inhouse. the ciprofloxacin hcl working standard, lot number xlm0725369 with purity or potency of 99.87% was obtained from aurobindo pharmaceutical industries (india). 2.2 methods six brands of ciprofloxacin 500 mg tablets were used in the study. identity, weight uniformity, dissolution test and assay for the content of active ingredients were done as described in the british pharmacopoeia (bp, 2004). all the assays were carried out in triplicate except the dissolution tests which were done six times as indicated in bp. dissolution profiles were constructed for each drug product. 2.2.1 identification test the identity of the drug was confirmed by high performance thin layer chromatography (hptlc) with silica gel 60f254 pre-coated (10x20) cm obtained from merck (uk). the mobile phase was consisted of a mixture of methanol, dichloromethane, ammonia and acetonitrile (40:40:20:10) as stated in bp 2004. a test solution of 0.05% w/v was prepared by mixing 750 ml of water with powdered tablets of ciprofloxacin equivalent to 2 gm of ciprofloxacin in ultrasonic © cncs mekelle university 96 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 bath for 20 minutes and further diluted to 1000 ml. a standard solution of ciprofloxacin hydrochloride was prepared by dissolving 58 mg with 100 ml of the mobile phase. a third solution, which was a 1:1 mixture of the reference and test solution, was prepared. a 10 µl of each of the solutions was applied separately as bands on pre-coated silica gel plate. the plates were placed in a suitable chromatographic chamber and the chromatogram was developed using the aforementioned solvent system. the plate was removed after the solvent has moved about three-fourth of the plate. the plate was dried in air for 15 minutes and examined under uv-light, 254 nm. the distance of each spot from the point of origin was marked with a pencil, measured and recorded. 2.2.2 weight uniformity test the test for uniformity of weight for each brand of ciprofloxacin tablets was carried out as described in bp 2004. the weights of twenty tablets were determined individually using an electronic micro balance; model aaa 250l, adams co. (uk). the mean tablet weight and standard deviation were calculated. 2.2.3 disintegration time (dt) test disintegration time test for the tablets was carried out according to the specification given in bp 2004. a 900 ml beaker was filled with 37 ± 0.5oc water. six tablets were placed into the basketrack assembly and connected to the disintegration apparatus. the apparatus and the timer were started simultaneously and the time required for each tablet to disintegrate was recorded and the average time calculated. 2.2.4 dissolution dissolution test was done according to bp 2004 specifications using dissolution apparatus type ii (paddle apparatus) obtained from pharma test (germany). vessels consisting of 900 ml of water as the dissolution medium were employed. the vessels were added to a circulating water bath maintained at 37 ± 0.5oc and allowed to equilibrate. once the desired temperature was attained, the tablets were added to the center bottom of the vessel and the paddle was rotated at 50 rpm. 10 ml samples of the dissolution medium were withdrawn from each vessel using a syringe after 10, 20, 30, 40, 50 and 60 minutes and an equivalent amount of the dissolution medium was immediately introduced as a replacement. the samples were filtered and suitably diluted with the dissolution medium. the concentrations were determined by measuring the absorbance at 276 nm using a uv/vis spectrophotometer, spectro genesis 5 (uk). solution of ciprofloxacin © cncs mekelle university 97 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 reference standard was also prepared using the dissolution medium and absorbance was measured. water was used as a blank. all the necessary corrections for dilution were made when calculating the percent of drug released and calibration curve for the dissolution was set. 2.2.5 assay of ciprofloxacin tablets all the eight drug products were assayed for the drug content according to the method outlined in the individual drug monographs of the british pharmacopoeia (bp, 2004). the assay was carried out using hplc. the hplc system consisted of a solvent pump (model lc-10at vp), an uvdetector (spd-10a vp), a system controller (scl-10a vp), a degasser (dgu-14a), a software (class vp version 5.02) all from shimadzu instruments (japan). a stainless steel column of ods (25 cm x 4.6 mm) obtained from teknokroma, s. coop. company ltd (spain, barcelona) was packed with stationary phase of 7 µm particle size; uv-vis detector at 278 nm; mobile phase: a mixture of acetonitrile and phosphoric acid the ph of which was adjusted to 3.0 with triethylamine (tea) in the ratio of 20:80 (v/v); flow rate of 2 ml/min; injection volume: 10 µl; and oven temperature: 40oc. twenty tablets were weighed and finely powdered. a quantity of the powdered tablets containing the equivalent of 0.5 gm of ciprofloxacin was added to 250 ml of water. the solution was sonicated for 20 minutes and filtered. a portion of the filtrate (25 ml) was withdrawn and diluted with sufficient amount of the mobile phase to give 100 ml solution. 58 mg of the reference standard was dissolved in 100 ml of the mobile phase. the solutions were made ready on the sample vials and 10 µl of each were injected to the system at intervals. the assays were repeated three times and the results presented were the mean of the three determinations. the content of ciprofloxacin was calculated from the peak areas of the chromatograms of the test and reference standard solutions and the declared content of ciprofloxacin in ciprofloxacin hydrochloride reference standard. 2.2.6 data analysis analytical data obtained from the experiments carried out were analyzed using origin® graphing and scientific analysis software program for manipulating and drawing of dissolution profiles; and grahpad instat demo software program for statistical comparisons of dissolution profiles. © cncs mekelle university 98 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 3. results and discussion 3.1 identification test of ciprofloxacin tablets the thin layer chromatographic (tlc) results for the identification of the drug samples are shown in table 2. the retention factor (rf) of both the sample and the reference substance was calculated and compared. the tlc plates were examined under uv-light of 254 nm. the results from table 2 revealed that the rf values of the samples and the reference standard were almost the same. thus, all the samples examined for the identity of the active ingredient passed the identification test as per the bp and usp/nf specifications. table 2. comparison of tlc retention factor (rf) values of different brands of ciprofloxacin tablets with a reference standard. brand name rf (sample) rf (standard) ciprodac 0.85 0.86 ciprodenk 0.86 0.86 ciprofloxacin 0.85 0.86 quintor 0.87 0.86 floxine 0.88 0.86 ciflox 0.86 0.86 3.2 weight uniformity test the results of weight uniformity test are depicted in table 3. the mean tablet weight, the number of tablets within and outside the bp specification limit range for the different products is included. weight uniformity test is required to assure that the drug content in each unit dose is distributed in a narrow range around the label strength. if the drug substance forms the greater part of the oral solid dosage form, any weight variation obviously reflects variation in the content of active ingredient. according to the specification outlined in bp 2004, the test for uniformity of weight for drug products where the strength is >250 mg (film coated tablets), a ±5% of the average pass the test for uniformity of weight. the results, thus, indicate that six of the products possess acceptable uniformity of weight as per the pharmacopoeia limit. moreover, the relative standard deviation of the products is less than 6 and the number of tablets outside the bp range is within the limit stipulated in the pharmacopoeia. © cncs mekelle university 99 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 table 3. uniformity of weight for the randomly selected ciprofloxacin 500 mg tablets (n=20). brand name mean (mg) of 20 determinations ±rsd (%) no. of tablets within the bp range no. of tablets outside the bp range ciprodac 752.50 3.33 18 2 ciprodenk 732.20 0.83 20 0 ciprofloxacin 760.80 5.34 19 1 quintor 749.51 0.50 20 0 floxine 738.05 0.95 20 0 ciflox 685.60 1.02 20 0 3.3 disintegration test the mean disintegration times of the different brands of the ciprofloxacin tablets included in the study is shown in table 4. as indicated in the table, the mean disintegration time for all the products was within the pharmacopoeia limit. for a drug to be absorbed from a solid dosage form after oral administration, it must first be in solution, and the first important step toward this condition is usually the break-up of the tablet; a process known as disintegration. according to the bp 2004, the time limit for disintegration of film coated tablets is <30 min. all the products comply with the outlined specification time for disintegration of film coated tablets. moreover all the drug products had a mean disintegration time of less than five minutes. table 4. disintegration time (dt) of randomly selected ciprofloxacin 500 mg tablets (n=6). brand name mean (min) of six determinations ±rsd (%) ciprodac 3.00 0.22 ciprodenk 2.00 0.10 ciprofloxacin 4.00 0.00 quintor 3.00 3.16 floxine 4.00 0.40 ciflox 4.00 1.00 3.4 assay of ciprofloxacin tablets the results for the mean percentage label claim of the different brands of ciprofloxacin 500 mg tablets included in the study are depicted in table 5. the products were assayed according to the method outlined in bp, 2004. in this, it is described that ciprofloxacin tablets should contain not less than 95.0% and not more than 105.0% of the stated amount. as indicated in table 5, all brands of ciprofloxacin tablets passed as per the bp specification. the highest percentage content was obtained for ciprodac (105.78) %, while the least drug content was obtained for ciflox © cncs mekelle university 100 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 (98.70) %. statistical comparison for drug content indicates that with 95% confidence interval, there is exists significant difference in the drug content among the different brands (p<0.05). 3.5 dissolution test the dissolution profile of the six brands is illustrated in figure 1 and their chromatograms are indicated in figures 2, 3 and 4; and for reference standards in figure 5. products with different formulations, different inactive ingredients, and different formulation design may have different dissolution profiles or release characteristics and therefore may have different bioavailability. in the present study, the dissolution profiles of the six products were tested according to the method described in the bp, 2004. it is stated that the amount of ciprofloxacin released within 30 minutes is not less than 80% of the stated amount. table 5. the percentage drug content of randomly selected ciprofloxacin 500 mg tablets (n=20). brand name mean percentage label claim (mean of triplicate determinations) ±rsd ciprodac 105.78 0.085 ciprodenk 101.95 0.048 ciprofloxacin 100.23 0.056 quintor 105.65 0.101 floxine 102.51 0.102 ciflox 98.700 0.102 figure 1. dissolution profiles of the different brands of ciprofloxacin tablets in water medium. all the brands of ciprofloxacin tablets studied released more than 80% within 30 minutes except ciflox which has released only 77.60 (±2.84). hence, five of the products complied with the bp © cncs mekelle university 101 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 and usp dissolution tolerance limits i.e. not less than 80% of the drug is released in 30 minutes but ciflox failed to release the stated amount. it was observed that ciprodenk with the smallest disintegration time (2 min) had a mean percentage drug release of 90.31% within 30 minutesthe maximum of all the brands investigated. this is in line with the general concept that fast disintegrating tablets release their drug substance easily and vice versa. figure 2. hplc chromatograms of the two brands of ciprofloxacin tablets with sample codes c001 and c002. sample code © cncs mekelle university 102 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 in general, the six brands showed differences in their drug release in vitro which could also result in differences in their bioavailability in vivo. however, in vitro testing only predicts the in vivo bioavailability and bioequivalence of oral solid dosage forms. it does not exclusively indicate the in vivo performance of a drug. the value of dissolution as a quality control tool for predicting in vivo performance of a drug product is significantly enhanced if an in vitro-in vivo relationship (correlation or association) is established (fda, 1997; sathe et al., 1997, 2001). figure 3. hplc chromatograms of the two brands of ciprofloxacin tablets with sample codes c003 and c004. © cncs mekelle university 103 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 figure 4. hplc chromatograms of the two brands of ciprofloxacin tablets with sample codes c005 and c006. © cncs mekelle university 104 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 figure 5. hplc chromatograms of the reference standard. 4. conclusion the study attempted to assess the quality of ciprofloxacin tablets and the physicochemical equivalence of the six brands. the physicochemical evaluation showed that all of the ciprofloxacin tablets tested for identity of the active ingredient, weight uniformity, and disintegration time complied with the pharmacopoeial specifications described in the bp and usp/nf. moreover, the ciprofloxacin tablets included in the study have mean drug content within the compendial tolerance limits. statistical comparison for drug content indicates that with 95% confidence interval, there is no significant difference among the brands (p<0.05). five brands complied with the bp and usp dissolution tolerance limits but ciflox failed to release the stated amount. in addition, the six brands showed that there is significant difference in the drug release in vitro (p<0.05). to justify the specification limits of the in vitro dissolution test, further study should be made to establish a meaningful correlation between in vitro release characteristics and in vivo bioavailability parameters. hence, the safety, quality and efficacy of essential drugs in the region, should be continuously monitored through post marketing surveillance practices. 5. acknowledgements the authors would like to thank mekelle university for the financial support and the ethiopian drug administration and control authority for providing laboratory facility for this research work. © cncs mekelle university 105 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 6. references alubo, s.o. 1994. death for sale: a study of drug poisoning and deaths in nigeria. soc. sci. med., 38: 97-103. british pharmacopoeia b. p, 2004. her majesty’s stationery office, london, vol. iii. chow, s. 1997. pharmaceutical validation and process controls in drug development. j. drug information., 31: 1195-1201. covington, t.r. 1992. generic drug utilization: overview and guidelines for product use. clin. res. reg. affairs, 9: 103-126. fda, 1997. center for drug evaluation and research (cder): guidance for industry: dissolution testing of immediate release solid oral dosage forms, pp. 6-8. graciela, i.r. 2001. argentina to crack down on pharmaceutical black market. the lancet, 358: 47. hebron, y., tetteyy, j.a., pournamdari, m & watson, d.g. 2005. the chemical and pharmaceutical equivalence of sulphadoxine/ pyrimethamine tablets sold on the tanzanian market. j. clin. pharm. ther., 30:575-581. itiola, o.a & pilpel, n. 1996. effects of interacting variables on the disintegration and dissolution of metronidazole tablets. pharmazie, 51: 987-989. kaymba, p.c., risha, p.g & shewiyo, d. 2004. the quality of essential antimicrobial and antimalarial drugs marketed in rwanda and tanzania: influence of tropical storage conditions on in vitro dissolution. j. clin. pharm. ther., 29: 331-338. menkes, d.b. 1997. hazardous drugs in developing countries. the market may be healthier than the people. british med. j., 315: 1557. meredith, p. 2003. bioequivalence and other unresolved issues in generic drug substitution. clin. ther., 25: 2875-2890. miller, sw & strom, jg. 1990. drug product selection: implications for the geriatric patient. the consultant pharmacist, 5: 30-37. newton, p., proux, s., green, m., smithuis, f., rozendaal, j., prakongpan, s., chotivanich, k., mayxay, m., looareesuwan, s., farrar, j., nosten, f & white, n.j. 2001. fake artesunate in southeast asia. the lancet, 357: 1948-1950. pecoul, b., chirac, p., trouiller, p & pinel, j. 1999. access to essential drugs in poor countries: a lost battle? am. j. med. ass., 281: 361-367. © cncs mekelle university 106 getu, k and awot, g.e (mejs) volume 2 (1): 93-107, 2010 risha, p.g., vervaet, c., vergote, g., bortel, l.v & remon, j.p. 2003. drug formulations intended for the global market should be tested for stability under tropical climatic conditions. european j. clinical pharmacology, 59: 135-141. sathe, p., tsong, y & shah, v.p. 1997. in vitro dissolution profile comparison and in vitro in vivo relation: carbamazepine case. adv. exp. med. biol., 432: 31-42. sathe, p., tsong, y & shah, v.p. 2001. in vitro dissolution profile comparison and in vitro in vivo relation: carbamazepine case. pharm. res., 18: 1729-1734. shakoor, o., taylor, r.b & berhens, r.h. 1997. assessment of the incidence of substandard drugs in developing countries. trop. med. int. health., 2: 839-845. taylor, r.b., shakoor, o & behrens, r.h. 2001. pharmacopoeial quality of drugs supplied by nigerian pharmacies. the lancet, 357:1933. ten ham, m. 1992. counterfeit drugs: implications for health. adverse drug reactions and toxicology reviews ii, pp. 59-65. who, 1996. technical report series no. 863. expert committee on specifications for pharmaceutical preparations. 34th report world health organization, geneva. who, 2005. regional strategy for improving access to essential medicines in the western pacific region 2005-2010. world health organization, geneva. © cncs mekelle university 107 research article http://dx.doi.org/10.4314/mejs.v15i1.5 momona ethiopian journal of science (mejs), v15(1): 62-77, 2023 ©cncs, mekelle university, issn:2220-184x submitted on: 24 th october 2018 revised and accepted on: 13 th february 2023 the effect of anethum graveolens on male fertility: systematic review and meta-analysis seid mohammed, birhane alem berihu* and tekleberhan beyene department of anatomy and histology, institute of biomedical sciences, college of health sciences, mekelle university, mekelleethiopia (mseid64@yahoo.com, *birhane.alem@mu.edu.et, teklitina@gmail.com). abstract the literature survey has reported that anethum graveolens extract is inescapably linked with fertility. recent studies showed that the aqueous extract of anethum graveolens extract has an adverse effect on male fertility by affecting serum testosterone level, sperm concentration as well as sperm motility. however, its evidence has not been established. the present paper tries to determine the level of evidence for the effect of dill (anethum graveolens) on male fertility. medline, cochrane library, pubmed, academic search complete, sport discus, science direct, scopus, web of science, and google scholar were searched to retrieve the literature used for this review. keywords utilized across the database search were dill, anethum graveolens, mice, male fertility, randomized control trial, and experimental. the search was limited to studies in animals; published in the english language. meta-analysis was conducted to examine the effect of anethum graveolens (dill) extract administration on male fertility. the overall methodological quality of evidence was assessed using the pedro scale. out of 25 studies, four trials met the inclusion criteria for this review. all the studies were included in the meta-analysis. of these, four studies were included for the analysis of sperm concentration, three studies for sperm motility, and two studies for serum testosterone hormone levels. the meta-analysis results suggested there were no significant differences between male fertility and other interventions in the effects of inducing male infertility. the number of studies regarding the current topic is scarce. the overall quality of evidence was very low. therefore, it is difficult to conclude whether the aqueous extract of dill seed has or has no adverse effect on male fertility. considering our meta-analysis, we recommended that there is a need for further investigation to provide adequate evidence for the effect of dill (anethum graveolens) on male fertility. keywords: anethum graveolens, dill, male fertility, randomized control trial, quesi experiment. 1. introduction the plant anethum graveolens is useful medicinal plant belonging to family umbelliferae and is a strong-smelling fennel-like, annual plant reaching a height of about four feet (monsefi et al., 2014). ethno medical value of anethum graveolens is tremendous in traditional medicine as different parts of the plant have been used as antibacterial, antioxidant, anti-hypercholesterolemia, and cancer chemo preventive effects. additionally, in folk medicine, it is commonly used to improve gastric irritation, indigestion, stomachache, insomnia, and colic (hosseinzadeh et al., 2002). studies reported that the anethum graveolens seed aqueous extracts decreases sexual potency and mailto:mseid64@yahoo.com mailto:*birhane.alem@mu.edu.et seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 63 issn: 2220-184x spermatogenesis in males (weiss and meuss, 2001; duke, 2002). high doses of anethum graveolens seed aqueous and ethanol extracts caused the significant increase in duration of the estrous cycle, diestrus phase and progesterone concentration (monsefi et al., 2006a; monsefi et al., 2006b). utilization of the anethum graveolens increases milk production and promotes menstruation (weiss and meuss, 2001).the anethum graveolens leaf is used as food flavoring and aroma (de carvalho and da fonseca, 2006; jana and shekhawat, 2011). the anethum graveolens seed stimulated progesterone secretion and affect menstrual cycle (monsefi et al., 2006a,b). it is undeniable that the increase of the population in the developing countries is an anxiety, therefore finding safe and effective family planning involving male can be very useful. lack of male involvement may be due to in part to the limited contraceptive choice that they have (mahmood and ringheim, 1996). so, it requires more research to develop new methods for them. thus, several medicinal herbs have tested on animal models. therefore, traditionally plants have been used to control fertility (mahmood and ringheim, 1996). recent studies suggest that anethum graveolens extract has the anti-fertility effect on the male reproductive functions (khouri and el-akawi, 2005; sailani and moeini, 2007). in contrast, some research suggests that anethum graveolens extract enhances the aphrodisiac activity and is not harmful to sperm and male reproductive organs (madhukar and rajender, 2009). prior to the present systematic review, there was no systematic review conducted to identify the level of evidence on the effect of the anethum graveolens on the male reproductive functions. it is reasonable to pool investigations to establish evidence on the effect of the anethum graveolens on the male reproductive functions. therefore, the objective of this systematic review and meta-analysis was to determine the level of evidence for the effect of dill (anethum graveolens) on male fertility. 2. methods 2.1. protocol and registration protocol followed as per the cochrane guidelines and conducted based on preferred reporting items for systematic reviews and meta-analyses (prisma) checklist (deeks et al., 2008). seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 64 issn: 2220-184x 2.2. data sources and search strategy this review was conducted according to the cochrane guidelines and has been presented based on the preferred reporting items for systematic reviews and meta-analyses checklist. mendeley, cochrane library, pubmed, academic search complete, science direct, and google scholar were searched to retrieve the papers for this review. keywords utilized across database search were anethum graveolens, male fertility, mice, randomized control trial, and experimental study. as subject headings varied between the databases, various combinations of these keywords were used. the search was limited to the studies in an animal, published in the english language. a search of bibliographies of acquired studies was also performed. authors have independently conducted the database searches. in addition, four relevant journals (fig 1) and reference lists of included studies were manually searched. the database searching was performed since september 2017. figure 1.the process of study selection according to the prisma flow diagram. 2.3. types of studies to retrieve the papers for this review, studies using the randomized controlled trials (rcts) and quasi experimental study were included in this study. only articles published in the english language limited to animal studies were included in this study. for the present review, the focus is seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 65 issn: 2220-184x being about the effect on male fertility (effect on sperm concentration, sperm motility, and testosterone hormone level). research articles conducted on animals using extracts in addition to anethum graveolens extract were included. brief trial reports, abstracts, and proceedings from the conference were excluded from the study. 2.4. intervention the intervention of interest was the effect of the anethum graveolens extract on sperm concentration, sperm motility, and testosterone hormone. studies with anethum graveolens administration did as the only intervention or with other interventions were included if the same other interventions were applied in the control group. if the exclusive effect of anethum graveolens extract administration could not be defined in studies involving multiple interventions, those were excluded from the study. 2.5. comparison control groups included no treatment or any form of intervention. 2.6. outcome measures assessment of sperm concentration, sperm motility, and other testosterone abnormalities were the main outcome measures. studies showing abnormalities as at least one of outcome measures were included. 2.7. data extraction authors have independently reviewed all articles for eligibility (fig 1). for conducting the metaanalysis, outcome data were assessed for eligibility, and scores were extracted from relevant included studies. data was extracted from the included studies (table 1) with the standardized form and checked the data to ensure accuracy. any disagreements regarding the study inclusion of two reviewers were resolved through discussion. the following were recorded from each trial where available: intervention characteristics (anethum graveolens extract dose, control condition, and additional treatments); participant characteristics (sex , age, and weight); study characteristics (author and publication year); outcomes (time of outcome assessment and unit of outcome assessment); and evaluation of each domain of the cochrane risk of bias assessment tool (sequence generation, allocation concealment, blinding, incomplete outcome data, and selective outcome reporting) (deeks et al., 2008). the outcome was decreased sperm concentration, sperm motility diminished and decreased testosterone hormone level. seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 66 issn: 2220-184x table 1. characteristics of the included studies. study study design intervention outcome measure reported results (shojaee, ghasemi et al., 2014) randomized control trial anethum graveolens seeds extract the effects of anethumgraveolens l. on the reproductive system of male rat and crem gene expression in testis of the rat. anethum graveolens has specific inhibitory effects on sperm parameters and reproductive functions of male rats, which is probably performed by a reduction of the level of crem expression. (maliheza man and sara, 2007) quasiexperimental study anethum graveolens seeds extract the infertility effect of anethumgraveolens the administration of anethum graveolens seeds aqueous extract did not have antifertility effects in adult male rats. (azarpoor and sarami, 2013) randomized control trial anethum graveolens leaf extract the effects of anethum graveolens juice (pj) consumption on sperm quality, spermatogenic cell density, antioxidant activity and testosterone level of male healthy rats anethum graveolens increase in epididymal sperm concentration, sperm motility, spermatogenic cell density and diameter of seminiferous tubules and germinal cell layer thickness, and it decreased abnormal sperm rate (iamsaard, prabsattroo et al., 2013) randomized control trial anethum graveolens extracts effect of anethumgraveolens extracts on the mounting frequency, histology of testis and epididymis, and sperm physiology anethum graveolens significantly increased the mounting frequency, at testis of the mice treated with anethum graveolens showed high levels of phosphorylated protein. anethum graveolens extract did not affect the sperm concentration, acrosome reaction, and histological structures of testis and epididymis. 2.8. assessment of methodological quality and risk of bias authors have used the pedro scale to assesses 11 items related to the study internal validity and statistical reporting, except for the first one (eligibility criteria), which is not computed in the total score. each item is scored as either present (1) or absent (0), leading to a maximum score up to 10. as shown in table two the methodological quality of the included studies was assessed using the pedro scale. a study with the score of 6 or above was considered of high quality (herd and meserve 2008) whereas that with the score of 5 or below was noted as low quality. the risk of bias in the included studies was assessed using 7 criteria recommended by the cochrane collaboration (higgins et al., 2011). the results of assessing the risk of bias were planned a priori to be used in evaluating the quality of evidence and in sensitivity analysis where appropriate. seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 67 issn: 2220-184x 2.9. data analysis a standard mean difference (smd) with 95% confidence interval (ci) was an effective measure used for the outcome. a weighted mean difference (wmd) with 95% ci was used to synthesize the level of sperm concentration, sperm motility, and testosterone. the data synthesis has been done with an intention to treat basis. the random effect model was used throughout the review for calculating wmds and smds. the inconsistency of data was examined by looking at the graphical display of the results and by using an i2. the i2 is provided with the forest plots as a useful estimate of heterogeneity. as recommended, an i2 of 50 % or more indicates high inconsistency of data (deeks et al., 2008). meta-analyses were conducted to examine the effects of anethum graveolens extract on sperm concentration, sperm motility, and testosterone level in comparison with control groups. publication bias was assessed by graphically examining the symmetry of a funnel plot. review manager 5.3 was used for all analyses and generating the funnel plot. the forest plot is a figure that appears in the results section of a systematic literature review. it's a graphic representation of the findings of multiple studies that investigated the same scientific question and measured the same outcome. funnel plots are a visual tool for investigating publication and other bias in meta-analysis. they are simple scatterplots of the treatment effects estimated from individual studies (horizontal axis) against a measure of study size (vertical axis). 3. results 3.1. type of studies and their characteristics the process of the selecting studies to be included in this meta-analysis and systematic review is illustrated in figure 1. four articles from a total of 25 records were included in this systematic review. the characteristics of the included studies are presented in table 1. three studies were rcts, and one study was quesi experimental published in the english language. 3.2. interventions variety in comparison interventions was shown in the present meta-analysis. these included effects of both daily administrations of anethum graveolens seeds and leaf extract on male rats. 3.3. primary outcomes studies analyzed in this review revealed that dill (anethum graveolens) shows no significant effect on sperm concentration, sperm motility, and testosterone level. seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 68 issn: 2220-184x table 2. pedro scale criteria. authors of study pedro scale criteria pedro 1 2 3 4 5 6 7 8 9 10 11 (shojaee, ghasemi et al. 2014) y y n n y n y n y n 5 (malihezaman and sara 2007) n n y n y n y n y n 4 (azarpoor and sarami 2013) y y y y n y y y y y 9 (iamsaard, prabsattroo et al. 2013) y y n y y n y n y n 6 note: y: criteria met. n: criteria not met. 1. eligibility criteria were specified 2. subjects were randomly allocated to groups 3. the allocation was concealed 4. the groups were similar at baseline 5. there was blinding of all subjects 6. there was blinding of all administration who administered the intervention 7. assessors blinding. 8. adequate data collection. 9. intention to treat analysis 10. between-group statistical comparison 11. point measures and measures of validity. 3.4. methodological quality and risk of bias the results for pedro score of each study are presented in table 2. the scores ranged from 4 to 9. two studies were considered of low quality (shojaee et al., 2014; malihezaman and sara, 2007) while other two studies of high quality (iamsaard et al., 2013; azarpoor and sarami, 2013). three criteria which were eligibility criteria were specified, intention to treat analysis, point measures and measures of validity were unsatisfied in all studies. figure 2 shows the summary of assessing the risk of bias. studies successfully perform low risk of selection bias, allocation concealments, blinding of participants, personnel, and performance bias. there was risk of reporting bias, attrition bias, and detection bias across the included studies. 3.5. publication bias it was difficult to determine if there was publication bias from the funnel plot because of the small numbers of studies (fig 3). seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 69 issn: 2220-184x figure 2. risk of bias graph: review authors' judgments about each risk of bias item presented as percentages across all included studies. figure 3. funnel plot of comparison: effect of the anethumgraveolens seed extract on sperm concentration. 3.6. effect of the dill (anethum graveolens) on male fertility four different studies were considered for this meta-analysis (shojaee et al., 2014; malihezaman and sara, 2007; azarpoor and sarami, 2013; iamsaard et al., 2013). as heterogeneity was evidenced in all meta-analyses (heterogeneity: τ =8.63; χ2 = 55.4, df = 3 (p <0.00001); i² =95%), (fig 2), the random effect model was used, and it generated the weights from inverse-variance weighting. in terms of the effects of dill (anethum graveolens ) on sperm concentration in seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 70 issn: 2220-184x comparison with the control group, four studies were identified (malihezaman and sara, 2007; azarpoor and sarami, 2013; iamsaard et al., 2013; shojaee et al., 2014). the overall estimate of the effect on sperm concentration suggested that there was no significant difference between exposed and control group for the reduction of sperm concentration (smd: -1.13, 95% ci: -4.382.13, p: 0.50) (fig 4). similarly, the overall estimate of the effect on sperm motility suggested that there was no significant difference between exposed and control group for the reduction of sperm motility (smd: -0.80, 95% ci: -1.64-0.03, p: 0.06) (fig 5). figure 4. forest plot of comparison: effect of the anethumgraveolens seed extract on sperm concentration. figure 5. forest plot: effect of the anethumgraveolens seed extract on sperm motility. figure 6. forest plot of comparison: effect of the anethumgraveolens seed extract on serum testosterone hormone level. study or subgroup azarpoor a. 2013 shojaee p. 2014 lamsaard et al 2013 monsefi m. 2007 total (95% ci) heterogeneity: tau² = 8.63; chi² = 55.41, df = 3 (p < 0.00001); i² = 95% test for overall effect: z = 0.68 (p = 0.50) mean 31.47 217.89 39 6.26 sd 1.11 2.23 9.56 0.16 total 10 8 10 10 38 mean 67.49 219.67 30 3.91 sd 1.29 2.45 8.46 0.85 total 10 8 10 10 38 weight 8.0% 31.0% 31.2% 29.8% 100.0% iv, random, 95% ci -28.67 [-38.62, -18.72] -0.72 [-1.74, 0.30] 0.95 [0.02, 1.89] 3.68 [2.13, 5.23] -1.13 [-4.38, 2.13] experimental control std. mean difference std. mean difference iv, random, 95% ci -50 -25 0 25 50 favours [experimental] favours [control] study or subgroup monsefi 2007 azarpoor 2013 shojaeeb p. 2014 total (95% ci) heterogeneity: chi² = 53.66, df = 2 (p < 0.00001); i² = 96% test for overall effect: z = 1.88 (p = 0.06) mean 78.78 27.7 64.63 sd 1.88 1.31 1.32 total 10 10 8 28 mean 78.33 55.39 75.32 sd 3.8 2.17 1.07 total 10 10 10 30 weight 91.0% 2.6% 6.4% 100.0% iv, fixed, 95% ci 0.14 [-0.73, 1.02] -14.80 [-19.99, -9.60] -8.59 [-11.89, -5.28] -0.80 [-1.64, 0.03] year 2007 2013 2014 experimental control std. mean difference std. mean difference iv, fixed, 95% ci -100 -50 0 50 100 favours [experimental] favours [control] study or subgroup monsefi 2007 shojaee p. 2014 total (95% ci) heterogeneity: tau² = 4.40; chi² = 14.11, df = 1 (p = 0.0002); i² = 93% test for overall effect: z = 0.39 (p = 0.70) mean 3.38 0.689 sd 1.14 0.032 total 10 8 18 mean 2.41 0.823 sd 0.9 0.076 total 10 8 18 weight 51.2% 48.8% 100.0% iv, random, 95% ci 0.90 [-0.03, 1.84] -2.17 [-3.48, -0.86] -0.60 [-3.61, 2.42] experimental control std. mean difference std. mean difference iv, random, 95% ci -100 -50 0 50 100 favours [experimental] favours [control] seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 71 issn: 2220-184x the overall estimate of the effect on serum testosterone level suggested that there was no significant difference between exposed and control group for the reduction of testosterone level (smd: -.60, 95% ci: -0.61-2.42, p: 0.70) (fig 6). the overall quality of evidence was very low (table 2). therefore, it is difficult to conclude whether the aqueous extract of dill has or no effect on male fertility. 4. discussion this systematic review and meta-analysis were conducted to determine the level of evidence for the effect of the extract of the dill (anethum graveolens) on male reproductive function. the results of the meta-analysis suggest that there is very low-quality evidence of no difference in the effect of the extract of the dill (anethum graveolens) on male fertility as compared to control group. on the other hand, the results of each study separately suggest that the extract of the dill (anethum graveolens) has shown antifertility effect (cruz‐casallas et al., 2005; khouri and el-akawi, 2005; sailani and moeini, 2007), although no significant difference is shown when analyzed based on reproductive parameters such as sperm concentration, sperm motility, and serum testosterone level. as the number of studies included in the analyses is very small (n =4), it is reasonable to think that these slightly conflicting results might show scarcity of studies regarding the effects of anethum graveolens on male fertility in demonstrating actual effects. two studies included in this meta-analysis (shojaee et al., 2014; azarpoor and sarami, 2013) have demonstrated that the administration of anethum graveolensto male mice induces reduction in the concentration of sperm in the center of seminiferous tubules. shojaee et al. (2014) have reported that there was a reduction in the diameter of seminiferous tubules following administration of the anethum graveolens. viable sperm is an essential component of any successful reproduction and the success of reproduction process is dependent on a supply of highquality gametes (cruz‐casallas et al., 2005). approximately 50% of infertility issues are attributable to malefactors. a number of different factors may result in similar reductions of sperm count or motility and affect sperm morphology (madhukar and rajender, 2009). one study on the administration of aqueous extract of anethum graveolens showed a significant reduction in the number and motility of sperm (sailani and moeini, 2007), this may be due to the influence of the extract on the cell cycle, cell division and expression of genes necessary for the spermatogenesis. it is also possible that these changes might be a result of changes in the microenvironment of seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 72 issn: 2220-184x epididymis and creation of a toxic microenvironment presence in anethum graveolens seed extract, thus influencing sperm count and motility (shojaee et al., 2014). it could also infer that the treatment may act directly or indirectly on the pituitary gland secretary function causing to a decrease in the androgen (sailani and moeini, 2007). it has been demonstrated that the process of spermatogenesis and the accessory reproductive organs functions are androgen dependent (khouri and el-akawi, 2005). therefore, any changes in the androgen production would reflect and explain the decrease in the number of sperms (sailani and moeini, 2007). at present, there are no truly dependable criteria for estimating sperm quality. in human, mammals, and fish, the length of time and intensity of spermatozoa motility, the percentage motile sperm and sperm density are all parameters that have been measured in an attempt to assess sperm quality (billard and cosson, 1992). moreover fertilizing capacity is the most conclusive way of testing sperm quality (billard et al., 1995). spermatozoa motility is the most commonly used criterion to evaluate semen quality (bozkurt et al., 2006). however, spermatozoa motility varies in rigor and duration not only among male but also within an individual male depending on the ripeness, age and time of sampling. the highest motility of the spermatozoa is observed at the peak of the breeding season (terner, 1986). in many species, sperm is stored to maintain a uniformly high sperm count even with a high ejaculatory frequency. in man, there is no storage, so sperm count is essentially a reflection of production rate, albeit modified by abstinence period. this difference between humans and other animals might sound incidental, but it is fundamentally important with regard to fertility (sharpe, 2003). a study done on ruta graveolens which is a similar species with anethum graveolens revealed that this medicinal plant significantly reduces sperm concentration (sailani and moeini, 2007). modern experiments have shown some effects exerted by ruta graveolens on male reproductive system and spermatozoa. a two-month oral administration of ruta graveolens aqueous extract in male albino rats suppressed testosterone levels, decreased sexual and aggressive behaviors, reduced sperm motility and count (khouri and el-akawi, 2005). sperm count reductions due to ruta graveolens have been reported in other studies (sailani and moeini, 2007). naghibi et al. (2010) have previously reported the immediate immobilizing effect of the ruta graveolens aqueous extract on human spermatozoa in vitro conditions (harat et al., 2008). the similar pattern has also been reported by other members of the family rutacea (gijon et al., 1995; clarke et al., 2006; harat et al., 2008). seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 73 issn: 2220-184x studies demonstrated that administration of anethum graveolens extract showed a reduction in testosterone hormone (shojaee et al., 2014). testosterone is synthesized from cholesterol in the leydig cells. the secretion of testosterone is under the control of lh and the mechanism by which lh stimulates the leydig cells involves the increased formation of cyclic amp via the serpentine lh receptor. testosterone exerts an inhibitory feedback effect on pituitary lh secretion (matthiesson et al., 2006). it appears that reduction in testosterone level causes a reduction in the inhibitory action of testosterone on lh secretion, thus the secretion of lh increase. along with testosterone, fsh is responsible for the maintenance of gametogenesis. fsh acts on the sertoli cells to facilitate the spermatogenesis (matthiesson et al., 2006). based on the studies, anethum graveolens extract has anti-fertility effect on the male reproductive functions, in contrast, our meta-analysis suggested that no statistical differences were observed between anethum graveolens extract administration and male fertility as compared to the control group. there are some issues to be considered in our meta-analyses. firstly, each study has relatively small sample sizes, resulting in only 76 participants in total whereas 200 subjects are considered as a sparse number in terms of grade system (gould et al., 2012). this might also have impacted on the difference between using absolute values and change scores. this difference suggests that there might be differences in assessment of the effect of the extract of the dill (anethum graveolens) on male reproductive function and control groups at baseline. however, such difference was not statistically different due to wide standard deviation caused by a small number of participants. secondly, the results are based on studies with low methodological quality, which may cause some biases. thirdly, the research design varies between studies and the three studies included were of randomized control trial (shojaee et al. 2014; iamsaard et al., 2013; azarpoor and sarami, 2013) and one study was quesi experimental (malihezaman and sara, 2007). two out of four studies demonstrated the short-term effects (acute and sub-acute effect) of the treatment of extract of the dill (anethum graveolens) intervention (iamsaard et al., 2013; malihezaman and sara, 2007) while two studies investigated the effect of the extract of the dill (anethum graveolens) administration for seven weeks and eight weeks (shojaee et al., 2014; azarpoor and sarami, 2013). fourthly, the duration of clinical symptoms was unclear in all the four studies. finally, the long-term effect anethum graveolens administration is unknown in addition to the exclusion of the nonenglish articles; therefore, language bias may not be ruled out. these factors could result significant seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 74 issn: 2220-184x influence on the results of this review. these limitations and the above-mentioned factors could make the validity of current results suspicious. 5. conclusions and recommendations the amounts of studies concerning the current topic are scarce. in addition, most of the included studies were considered of low methodological quality. these could lead to overestimating or underestimating the effect of anethum graveolens administration on male fertility. therefore, strong recommendations can’t be made for the effect of anethum graveolens extract on male fertility. to provide the evidence-based anti-fertility effect of the anethum graveolens extract, more research, especially high qualities randomized control trials, regarding the current topic are needed. also, it is important to set a valid demonstration, including acute, sub-acute, sub chronic, chronic investigation and employ both non-specific and specific determinations where feasible. abbreviations ag: anethum graveolens; rcts :randomized controlled trials; crem: testicular responsive element modulator ; pj : (punica granatum) graveolens juice; smd: standard mean difference; ci: confidence interval; wmd: weighted mean difference; df: degree of freedom; amp: adenosine mono phosphate molecule; lh: luteinizing hormone; fsh: follicular stimulating hormone; pedro: the physiotherapy evidence database 6. acknowledgements praise is to the almighty; i would like to extend my at most gratitude to my advisor, mr. birhane alem berihu (assistant professor of human anatomy) for his unreserved support and provision of valuable advice and ideas as of his golden time. i also thank mekelle university college of health sciences, institute of biomedical science, and human anatomy unit for giving me an educative opportunity to pave my future career. i would like also to share my gratitude with my classmates and my friends from my heartfelt thanks for their continuous support and strong encouragement throughout the finalizing of this systematic review. 7. conflict of interests no conflict of interests. https://en.mimi.hu/biology/adenosine.html#maintitle https://en.mimi.hu/biology/molecule.html#maintitle seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 75 issn: 2220-184x 8. reference azarpoor, a & sarami, a.t. 2013. the effect of anethum graveolens seed extract on testis and spermatogenesis in male wistar rats. international journal of agriculture and crop sciences, 6(21): 1429. 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produce this terpene. food chemistry, 95(3): 413-422. deeks, j.j., higgins, j.p., altman, d.g. & cochrane statistical methods group, 2019. analysing data and undertaking meta‐analyses. cochrane handbook for systematic reviews of interventions, pp.241-284. duke, j. a. 2002. handbook of medicinal herbs. crc press, 896p, https://doi.org/10.1201/9781420040463. gijon, e., cartas, l., lorenzana-jimenez, m & garcia, x. 1995. immobilization of frog sperm by exposure to ruta chalepensis extract. in proceedings of the western pharmacology society, 38: 53-54. gould, m.k., garcia, d.a., wren, s.m., karanicolas, p.j., arcelus, j.i., heit, j.a & samama, c.m. 2012. prevention of vte in nonorthopedic surgical patients: antithrombotic therapy and prevention of thrombosis: american college of chest physicians evidence-based clinical practice guidelines. chest, 141(2): e227s-e277s. https://doi.org/10.1201/9781420040463 seid mohammed, birhane alem berihu and tekleberhan beyene (mejs) volume 15(1):62-77, 2023 © cncs, mekelle university 76 issn: 2220-184x harat, z.n., sadeghi, m.r., sadeghipour, h.r., kamalinejad, m & eshraghian, m.r. 2008. immobilization effect of ruta graveolens l. on human sperm: a new hope for male contraception. journal of ethnopharmacology, 115(1): 36-41. herd, c.r & meserve, b.b. 2008. a systematic review of the effectiveness of manipulative therapy in treating lateral epicondylalgia. journal of manual & manipulative therapy, 16(4): 225-237. higgins, j.p., altman, d.g., gøtzsche, p.c., jüni, p., moher, d., oxman, a.d., savović, j., schulz, k.f., weeks, l & sterne, j.a. 2011. the cochrane collaboration’s tool for assessing risk of bias in randomised trials. bmj, 343, 343 doi: https://doi.org/10.1136/bmj.d5928. hosseinzadeh, h., karimi, g & ameri, m. 2002. effects of anethum graveolens l. seed extracts on experimental gastric irritation models in mice. bmc pharmacology, 2(1): 1-5. iamsaard, s., prabsattroo, t., sukhorum, w., muchimapura, s., srisaard, p., uabundit, n., thukhammee, w & wattanathorn, j. 2013. anethum graveolens linn.(dill) extract enhances the mounting frequency and level of testicular tyrosine protein phosphorylation in rats. journal of zhejiang university science b, 14: 247-252. jana, s & shekhawat, g.s. 2011. plant growth regulators, adenine sulfate and carbohydrates regulate organogenesis and in vitro flowering of anethum graveolens. acta physiologiae plantarum, 33: 305-311. khouri, n.a & el-akawi, z. 2005. antiandrogenic activity of ruta graveolens l in male albino rats with emphasis on sexual and aggressive behavior. neuroendocrinology letters, 26(6): 823-829. madhukar, d & rajender, s. 2009. hormonal treatment of male infertility: promises and pitfalls. journal of andrology, 30(2): 95-112. mahmood, n & ringheim, k. 1996. factors affecting contraceptive use in pakistan. the pakistan development review, 35(1): 1-22. malihezaman, m & sara, p. 2007. effects of aqueous extract of anethum graveolens on male reproductive system of 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and technology, 7(9): 1883-1886. terner, c. 1986. evaluation of salmonid sperm motility for cryopreservation. the progressive fish‐culturist, 48(3): 230-232. weiss, r.f & meuss, a.r. 2001. weiss's herbal medicine. isbn: 9781588900692, 158890069x, thieme publisher, 362p. © cncs mekelle university knowledge, attitude, and practice of voluntary counseling and testing for hiv among university students, tigray, northern ethiopia alemayehu bayray* department of nursing, college of health sciences, mekelle university, po box 231, mekelle, ethiopia (*alemayehub35@gmail.com) abstract the aim of this study was to assess the knowledge, attitude, and practice of voluntary counseling and testing (vct) for hiv in mekelle, tigray, ethiopia with a view of suggesting measures for increased up takes in university students. institution based cross-sectional study design was used. respondents were selected by simple random sampling method. a total of 425 students were included. the data was collected from april 1-10, 2008 by trained health workers using a self administered structured questionnaire which was adopted from behavioral survey surveillance (bss). a total of 413 students participated (with the response rate of 97%). in which 145 (35.1%) accounted for females. their age ranged from 18-30, with the median age of 20. majority 145(35.1%) of the respondents preferred the vct service to be given in youth clubs followed by government institutions 105(25.4%).the female respondents were found to have a significant association to accept vct for hiv with the or=1.95(1.27,2.99). in this study females were more knowledgeable and willing to vct for hiv than that of the males. still cost of vct matters, in which the respondents prefer to be tested at youth clubs and government hospitals. therefore, both sexes should have to be empowered to accept vct for hiv through peer initiated vct services at all levels of care including in universities. key words: vct, knowledge, behavior, practice. 1. introduction almost three quarters (72%) of all adult and child deaths in sub-saharan africa in 2005 have occurred due to aids (edhs, 2005). the devastating effect of hiv/aids in ethiopia has become more and more visible with time, and the life expectancy is estimated to have fallen from 50 years to 42 years. today 42% of the hospital beds in the country are estimated to be occupied by aids patients, draining the scarce resources allocated to the health sector. according to edhs 2005, 14% of adults (15-49 years) were reported infected with hiv in 2005 though its prevalence among adult men had been only 0.9%. further, infection levels are found to be higher in urban areas (5.5% among adults) compared to rural areas (0.7%) (edhs, 2006). in the recent years, number of people living with hiv has increased in every region in the world. it was particularly higher in east asia and in eastern europe and central asia, where the number in 2006 was over one fifth (21%) higher than in 2004. in many parts of the globe significant alemayehu, b (mejs) volume 2 (1): 108-118, 2010 number of adult women (15 years or older) are (than ever before) also reported to be living with hiv. in sub-saharan africa, for every ten adult men there are about 14 adult women infected with hiv. across all age groups, 59% of people living with hiv in sub-saharan africa in 2006 were women (unaids, 2002). hiv prevention programs must be differentiated and locally adapted to the relevant epidemiological, economic, social, and cultural contexts in which they are implemented. hiv prevention is for life, therefore, both delivery of existing interventions as well as research and development of new technologies require a long term policies of prevention should be in place and have to address norms & beliefs, recognizing both the key role they may play in supporting prevention efforts and the potential they have to fuel hiv transmission. a 2003 report from the global hiv prevention working group revealed that less than one in five persons is at risk of hiv and had access to basic hiv prevention services globally. it also revealed that only one in ten people living with hiv has even been tested for the virus. increased coverage with anti-retroviral treatment is expected to reduce the mortality and morbidity due to aids worldwide and will simultaneously provides countless new hiv prevention opportunities through client initiated and provider initiated routine (often of voluntary and confidential) good quality hiv counseling, testing and referral (unaids, 2002; moh, 2000). voluntary counseling and testing (vct) for hiv is acknowledged in the international arena as an effective and pivotal strategy for hiv/aids in terms of prevention and care. research conducted in kenya, tanzania, and trinidad by family health international in collaboration with unaids, who & the center for aids prevention studies (caps) at the university of california have shown that vct is an effective strategy for facilitating change in behavior. vct is also an important entry point for care and support. these findings have boosted interest and support for vct as a valuable component of comprehensive hiv/aids programs among international organization, including the national aids programs of many countries and donors (moh, 2000). vct is more than drawing and testing blood and offering a few counseling sessions. it is a vital point of entry to other hiv/aids services, including preventing motherto child transmission; preventing and clinically managing hiv-related illnesses, tuberculosis control, psychosocial and legal support (moh, 2000, 2002). vct provides benefits for those who test positive as well as those tests negative. vct alleviates anxiety, increases client’s perception of their vulnerability to hiv, promotes behavioral change, © cncs mekelle university 109 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 facilitates early referral for care and support, including access to antiretroviral therapy and helps reduce stigma in the community. it offers holistic approach that addresses hiv in the broader context of people’s lives, including poverty and its relationship to risky practices (unaids 2000). yet, several researches have been conducted to identify those factors that affect acceptance of vct in ethiopia. a study in north and south gondar administrative zones revealed that 82% of the respondents were willing to accept vct. the results of the behavioral variables showed that significance of relevant to their friends, families, religions leaders & couples were found to have statistically significant for vct acceptance (mengesha admasu, 2006). another study conducted in harar town about utilization of vct services, perceived barriers and preference of adolescents 15 – 24 yrs of age, majority of them (83.3%) felt that they were at either no or low risk of acquiring hiv and 92.2% responded that they have heard about vct, the most frequent and preferred source of information for vct being radio/television (59.2%). only 21.9% of adolescents reported that they had ever been tested for hiv. the commonly given perceived barriers of hiv tests were low risk perception and fear of stigma and discrimination if the follows test positive, more than half (55%) of adolescents preferred to be counseled by professionally of any sex but older than their age (lemessa, 2005 ). determinants of vct utilization among youth in jijiga town, ethiopia also identified that most commonly cited reason for vct utilization among the cases was to know their hiv status (61.6%) and for not being tested them among controls was fear to get the result (zenebu,2005). therefore, this study aimed to assess knowledge, attitude and practice of vct among university students. 2. methodology 2.1 description of the study area the study area mekelle is the capital city of tigray administrative region located about 776 kms north of addis ababa on addis ababa-adigrat national highway. it is one of the ethiopian towns growing rapidly in infrastructure and population. it is a special administrative city which consists of 10 kebelies, and a municipality. several governmental and nongovernmental services are given to the community. there are three governmental health centers and one referral and training hospital. further, voluntary counseling and testing (vct) service is given in © cncs mekelle university 110 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 five centers (trbh, 2005/6). mekelle university is one of the twenty one universities in ethiopia which currently enrolled more than ten thousand students. 2.2 study design a crosssectional survey was conducted to assess knowledge, attitude, and practice of vct for hiv among university students in mekelle, tigray, ethiopia. students of mekelle university (faculty of business, economics and law) were taken as study population. all the students who were volunteered to participate in the survey were included. the sample size was determined using the single population proportion formula with the following assumptions: positive attitude towards vct=50 %( to obtain the maximum sample size), degree of precision= 5%, level of confidence = 95% (z= 1.96), non-response rate 10%, the calculated sample size was 425. and these subjects were selected by a simple random sampling method after listing the name of the students alphabetically as a sample frame. the number of subjects to be selected from each class room was proportional to the population size of the class room. the response rate was 99%. the subjects who were absent during the study period were replaced by others. socio-demographic variables: sex, age, educational status, religion, ethnicity, acceptance of vct for hiv (knowledge, behavior/practice) 2.3 sample collection and processing to gather relevant information pertinent to the assessment of knowledge, attitude, and practice of vct for hiv among the university students a structured questionnaire was used. this self administered questionnaire was adopted from the ethiopian behavioral survey surveillance (bss) questionnaire. it includes three parts; the first section enquires about personnel data including age, sex, ethnicity, religion, marital status, and education level. the second part elicits awareness of existence of vct and vct services and its utilization, while the third part explores the normative beliefs of the respondents including their significant others (hapco, 2002). the study instrument was validated using a pre-test of randomly selected students of the university. the result of the pre-test study was used to modify content and wording of the questionnaire. four qualified nurses administered the questionnaire to the sample population. the questionnaire was prepared in english, which was translated to tigrinya language by experts. the data collectors were trained for two days about the purpose of the study and validity of filling the format properly and sincerely. the quality of data collection was supervised by the principal investigator during the data collection process. review and cross examination of the filled © cncs mekelle university 111 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 questionnaires was done daily by the assistant supervisors and the principal investigator; and necessary corrections and adjustments were made. the data collection took 10 days. table 1. socio-demographic characteristics of respondents (n=413), mekelle university, tigray, ethiopia, april, 2008. variables frequency(n=413) percent (%) sex male female 268 145 64.9 35.1 age <= 18 1924 25-30 66 343 4 15.9 83.1 0.9 educational status year i year ii year iii year iv 219 104 84 6 53 25.2 20.3 1.4 religion orthodox protestant catholic muslim others 266 88 29 20 10 64.4 21.3 4.8 7.0 2.4 ethnicity tigrian amhara oromo snnpr others 147 133 76 44 13 35.6 32.2 18.4 10.5 3.1 the raw data was entered into a computer and analyzed using spss version 13.0 statistical soft ware package. descriptive statistics was depicted using absolute numbers, simple percentages, range, and measures of central tendency (mean, median) as appropriate. the logistic regression used to test the significance of associations between categorical groups and other important associations (or, c.i, & p-value) was also calculated and the results were presented and interpreted, those who scored above the mean i.e. 17.8 were considered knowledgeable. those who scored above the mean i.e. 16.77 were considered to have good behavior or practice. © cncs mekelle university 112 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 table 2. preferences of the respondents for vct services offered, mekelle university, tigray, ethiopia, (n=413) april, 2008. preferred vct services n % govt. health institutions 105 25.4 private health institutions 49 11.9 ngos' 69 16.7 youth club 145 35.1 others 45 10.9 total 413 100 table 3. primary importance of vct services reported, mekelle university, tigray, ethiopia, (n=413) april, 2008. primary importance n % every body 251 59.6 commercial sex workers 7 1.7 drivers 4 1.0 students 12 2.9 pregnant women 32 7.6 all adults 49 11.6 children 31 7.4 couples for marriage 11 2.6 young people 9 2.1 people with multiple partners 9 2.1 total 413 100 table 4. respondents’ perception on how to behave if someone knows he/she is hiv positive mekelle university, tigray, ethiopia, (n=413) april, 2008. perceived behavior n % stop sexual intercourse 57 13.5 prevent pregnancy 17 4.0 plan for marriage 9 2.1 divorce 11 2.6 use a condom 25 5.9 seek medical help 78 18.5 commit suicide 40 9.5 tell others about his/her status 54 12.8 teach others 84 20.0 take care of him/herself 21 5.0 be religious 9 2.1 others 16 3.8 total 413 100 © cncs mekelle university 113 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 3. results a total of 413 people responded to the questionnaire out of 425 proposed study participants (with the response rate of 97%) in which females were 145 accounting 35.1%. 266 (64.4%) are from orthodox religion, 219 (52%) are from i year and 147(35.6%) are ethnically tigrians. their age is ranged from 18-30 years with the median age of 20 (table 1). among the respondents about 35.1% preferred the vct service to be given in youth clubs followed by 25.4% who preferred government institutions (table 2). many of them prioritized the primary importance of vct for hiv, and 251(59.6%) agreed for every body to have the test followed by all adults 49(11.6%), (table 3). eighty four (20%) of the respondents believed that if some one has tested hiv positive he/she should have to teach others about the condition followed by 78(18.5%) whom they preferred to seek medical help (table 4). (* refers to association) table 5. socio-demographic variables vs knowledge of the respondents, mekelle university, tigray, ethiopia, (n=413) april, 2008. knowledge of vct for hiv variables yes n (%) no n (%) crude or, 95%, c.i. adjusted or, 95%, c.i. sex male female 113(42.2) 81(55.9) 155(57.8) 64(44.1) 1 1.74(1.16,2.60)* 1 1.95(1.27,2.99)* educational status year i year ii year iii year iv 96(43.8) 60(57.7) 34(40.5) 4(60.0) 123(56.2) 44(42.3) 50(59.5) 2(40.0) 1 1.72(1.07, 2.40)* 0.86(0.51, 1.00) 1.88(0.31, 12.00) 1 1.72(1.05,2,82)* 0.84(0.49,1.45) 2.76(0.43,17.49) ethnicity tigray amhara oromo snnpr others 71(53.4) 68(46.3) 31(40.8) 19(43.2) 5(38.5) 62(46.6) 79(53.7) 45(59.2) 25(56.8) 8(61.5) 1 0.75(0.47,1.00) 0.60(0.34,1.00) 0.66(0.33,1.00) 0.55(0.17, 1.01) 1 0.88(0.54,1.45) 0.49(0.26,1.00) 0.64(0.31,1.32) 0.49(0.15,1.70) religion orthodox protestant catholic muslim others 107(40.2) 51(58.0) 14(70.0) 17(58.6) 5(50.0) 159(59.8) 37(42.0) 6(30.0) 12(41.4) 5(50.0) 1 2.05(1.26,3.00)* 3.47(1.29,9.00)* 2.11(0.97,4.00) 1.49(0.42,5.00) 1 2.56(1.49,4.37)* 3.88(1.39,10.75)* 2.49(1.09,5.72)* 2.53(0.67,9.58) © cncs mekelle university 114 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 further statistical analysis was done to check whether the socio-demographic characteristics of the respondents were associated with the knowledge about vct for hiv, and, female respondents were found to have a significant association with the or=1.95(1.27,2.99), pvalue=0.001 (table 5). statistical analysis was also done on whether the socio-demographic characteristics of the respondents were associated with the behavior/practice of vct for hiv, and no significant associations were found with the or=0.62(0.40, 1.00) for females and or=0.51(0.31, 1.01) for year ii students (table 6). (* refers to association) table 6. socio-demographic variables vs behavior/practice of the respondents, mekelle university, tigray, ethiopia, (n=413) april, 2008. behavior/practice of vct for hiv variables yes n (%) no n (%) crude or, 95%,c.i. adjusted or, 95%, c.i. sex male female 124(46.3) 81(55.9) 144(53.7) 64(44.1) 1 0.68(0.45,1.00) 1 0.62(0.40,1.00) educational status year i year ii year iii year iv 100(45.7) 65(62.5) 38(45.2) 2(20.0) 119(54.3) 39(37.5) 46(54.8) 4(80.0) 1 0.50(0.31,1.00) 1.01(0.61,3.00) 3.36(0.37,3.23) 1 0.51(0.31,1.01) 0.99(0.58,1.67) 2.59(0.27,24.33) ethnicity tigray amhara oromo snnpr others 75(56.4) 64(43.5) 37(48.7) 20(45.5) 9(69.2) 58(43.6) 83(56.5) 39(51.3) 24(54.5) 4(30.8) 1 1.68(1.05,2.00)* 1.36(0.77,2.00) 1.55(0.78,3.00) 0.58(0.17,1.00) 1 1.51(0.92,2.47) 1.58(0.87,2.86) 1.58(0.77,3.24) 0.54(0.15,1.94) religion orthodox protestant catholic muslim others 117(44.0) 51(58.0) 16(80.0) 15(51.7) 6(60.0) 149(56.0) 37(42.0) 4(20.0) 14(48.3) 4(40.0) 1 0.57(0.35,0.79) 0.20(0.06,0.1.00) 0.733(0.34,1.01) 0.52(0.14,1.00) 1 0.55(0.33,1.02) 0.19(0.06,1.04) 0.85(0.38,1.89) 0.49(0.12,1.90) 4. discussion the study had tried to look into the socio-demographic characteristics that might influence the knowledge, behavior/practice and preferences of vct for hiv among mekelle university students. voluntary counseling and testing for hiv is acknowledged within the international arena as an effective and pivotal strategy for both prevention and care in hiv/aids. majority 145(35.1%) of the respondents preferred the vct service to be given in youth clubs followed by government institutions 105(25.4%), and these could be because of the free service © cncs mekelle university 115 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 given at the youth club and the cheap payment in government hospitals and fear of stigma and discrimination. similarly, in harar majority of the adolescents preferred to be counseled by professionals of any sex but older than their age (lemessa, 2005). many of the respondents prioritized the primary importance of vct for hiv and agreed for everybody 251(59.6%) to have the test followed by all adults 49(11.6%); eighty four (20%) of the respondents believed that if someone has tested hiv positive he/she should have to teach others about the condition followed by 78(18.5%) whom they preferred to seek medical help. nearly eighty five percent of the respondents were willing to accept vct for hiv, and this was online with the study conducted in gondar (mengesha, 2006), in which 82% of the respondents were willing to accept vct. two hundred and forty one (58.4%) of the respondents believed that a person would not necessarily accept vct, unless he/she is planning marriage or to go abroad, in addition 102(24.2%) of the respondents said that hiv/aids has treatment, this is mainly related to lack of knowledge that may be thinking the haart (highly active anti-retroviral therapy) completely treats hiv/aids cases. after further statistical analysis female respondents were found to have more knowledge as compared with the male respondents with the or=1.95(1.27, 2.99), p-value=0.001, similarly year ii students were having significant association with the or=1.72(1.05, 2.82), and p-value of 0.002, this has an agreement with the study done on “utilization of vct services in harar town ethiopia” by lemessa (2005) in which female were found to have knowledge about vct. in another study by mengesha (2006) conducted in north and south gondar, it contradicts the above view and concludes that there is no significant difference between male and female in their knowledge about vct for hiv. the statistical analysis done on whether the socio-demographic characteristics of the respondents were associated with the behavior/practice of vct for hiv, and no significant associations were found with the or=0.62(0.40, 1.00) for females and or=0.51(0.31, 1.01) for year ii students, etc. and this could be as a result of small sample size included in this study. one of the main factors influencing vct for hiv was consequences of the test result that might lead in to stigma and discrimination leading to depression and hopelessness. © cncs mekelle university 116 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 5. conclusion in this study females were more knowledgeable and willing to vct for hiv than that of the males. still cost of vct matters, in which the respondents prefer to be tested at youth clubs and government hospitals. the other socio-demographic characteristics of the respondents in this study did not influence the acceptance of vct for hiv. both sexes should have to be empowered to accept vct for hiv through peer initiated vct services at all levels of care including in universities. governmental and non-governmental institutions should have to work on providing the vct service for the youth in a very cheap and extensive manner so as to increase the uptake of the vct for hiv. even though the study does not reflect the contribution of the socio-demographic characteristics of the respondents, much emphasis should have to be given in reducing stigma and discrimination of the group undergoing vct for hiv. 6. acknowledgement several people have indifferent and valuable ways contributed to the creation of this study. their assistance and input is acknowledged with appreciation. special thanks to: mekelle university, the interviewers, the interviewees, and the supervisor for devoting your time, sharing your knowledge and personal information, norad ii project for sponsoring this research and my families for their indifferent patience, and psychological support through out the study. 7. references edhs. 2006. preliminary report central statistical agency, addis-ababa, ethiopia. hapco. 2002. behavioral survey surveillance (bss) study in ethiopia. pp. 54-64. lemessa, o. 2005. utilization of vct services, perceived barriers and preferences of adolescents of 15-24 years of age in harar town, eastern ethiopia. pp.34-39. moh. 2004. aids in ethiopia, 5th edition, addis-ababa, ethiopia, pp.17-20. moh. 2000. guidelines for the prevention and control of selected epidemic diseases in ethiopia, department of disease prevention and control, moh, ethiopia, pp.71-81. moh, 2002 national guidelines for vct in addis-ababa, ethiopia. © cncs mekelle university 117 alemayehu, b (mejs) volume 2 (1): 108-118, 2010 mengesha admasu & yohanse fanta. 2006. factors affecting acceptance of vct in north and south gondar administrative zones, epha, addis-ababa, ethiopia. policy on hiv/aids of the federal democratic republic of ethiopia, august, 1998, 54-63. tigray regional health bureau, zonal health profile, 2005/06, pp.13-17. unaids. 2000. voluntary counseling & testing (vct), unaids technical update. 1st edition. pp. 23-28. who/unaids. 2002. report on the global hiv/aids. pp. 21-29. technical consultation on vct. 2004. models for implementation and strategies for scaling of vct services, geneva. unaids, report on the global hiv/aids epidemic. 4th edition, pp. 45-60. zenebu, y & yemane, berhane. 2005. determinants of vct utilization among youth in jijiga town, ethiopia. pp. 3-9. © cncs mekelle university 118 research article http://dx.doi.org/10.4314/mejs.v15i1.2 momona ethiopian journal of science(mejs), v15(1):17-31,2023 ©cncs, mekelle university, issn:2220-184x submitted on: 17 th august 2017 revised and accepted on: 13 th january 2023 detection of total fumonisins produced by fusarium verticillioides (sacc) isolates from maize kernels in ethiopia hadush tsehaye1,2*, leif sundheim2,3, arne tronsmo4, may bente brurberg2,3, dereje assefa1 and anne marte tronsmo2 1 department of dryland crop and horticultural sciences, p.o. box 231, mekelle university, mekelle, tigray, ethiopia (*had031@yahoo.com; hadush.tsehaye@gmail.com). 2 department of plant sciences, p.o. box 5003, norwegian university of life sciences, no1432 ås, norway. 3 biotechnology and plant health division, norwegian institute for bioeconomy research, p.o. box 5003, no-1431 ås, norway. 4 department of chemistry, biotechnology and food science, norwegian university of life sciences, p.o. box 5003, no-1432 ås, norway. abstract fusarium verticillioides is the most common fungal pathogen of maize in ethiopia. many strains of this pathogen produce fumonisin myotoxins that are harmful to human and animal health. this study was conducted to determine the fumonisinproducing ability of isolates of f. verticillioides isolated from maize kernels collected from different maizegrowing areas of the country. eighty f. verticillioides isolates were grown on autoclaved maize cultures for one month, and the fumonisin content was quantified using enzyme linked immunosorbent assay (elisa). all the 80 isolates evaluated were able to produce detectable levels of total fumonisins in the maize culture with values ranging from 0.25 to 38.01 mg of the toxin per kg of culture material (fungal biomass and maize kernels). the mean levels of total fumonisins produced by the f. verticillioides isolates were not significantly (p>0.05) different among maizegrowing areas, however, the total fumonisins levels produced by isolates obtained from the same area as well as agroecological zones were wide-ranging. the results indicate that the majority (57.5%) of the f. verticillioides isolates associated with maize grains in ethiopia produced total fumonisins >4 mg/kg, while 35% of the isolates produced total fumonisins <2 mg/kg. the widespread occurrence of higher fumonisinproducing strains across all maize growing areas in ethiopia indicates a possible food safety risk. thus, efforts should be made to prevent the spread of this fungus with good agronomic practices and to implore all possible ways to avoid maize contamination with fumonisin both in the field and in storage. keywords: agroecological zones, fumonisin, maize, kernel, food safety, ethiopia. 1. introduction maize (zea mays) is one of the major staple foods in ethiopia. it is second after teff (eragrostis tef zucc.) in area coverage (2.12 million ha), and has the highest average yield (3.2 tones/ha) than any other crop in the country (fao, 2015). the crop is grown in several agroecological zones of ethiopia, from moisture deficit semi-arid to moisture surplus areas (mosisa et al., 2012). fusarium verticillioides (sacc.) nirenberg is the most common fungal pathogen of maize in ethiopia (amare ayalew, 2010; hadush tsehaye et al., 2016). this fungus causes stalk and ear rot in maize and it is a prolific producer of dangerous mycotoxins known as mailto:had031@yahoo.com mailto:hadush.tsehaye@gmail.com hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 18 issn: 2220-184x fumonisins (munkvold and desjardins, 1997; picot et al., 2010). fusarium verticillioides is the most important fungal pathogen of maize in warmer climatic conditions worldwide (picot et al., 2010) and high amount of fumonisins are frequently found in maize and maize based products (bryla et al., 2013; sundheim and hadush tsehaye, 2015). this mycotoxin has also been reported at low levels in several other agricultural commodities such as sorghum, rice, wheat, barley, beans, asparagus and medicinal plants (bryla et al., 2013; sundheim and hadush tsehaye, 2015). in ethiopia, previous assessment of maize kernel samples collected from different maize growing areas indicated a widespread occurrence of fumonisin at concentrations ranging from 0.03 to 4.5 mg/kg (amare ayalew, 2010; hadush tsehaye et al., 2016). at least 28 different fumonisin molecules, which are extracted from natural samples or produced by fungi in artificial culture media in the laboratory, are known. these are classified into a, b, c and p series based on their chemical structures (falavigna et al., 2012; picot et al., 2010). members of the fumonisin b series (mainly fb1, fb2 and fb3) are the analogues that often occur in great quantities in naturally contaminated maize samples (bryla et al., 2013; stępień et al., 2011). fumonisin b1 is the most important one, as it accounts for more than 70% of all fumonisins found in naturally contaminated food and feed (nelson et al., 1991). among the minor fumonisin analogues, the c series are known to occur on moldy as well as normal non-moldy maize grains, while members of the fumonisin a and p series are secondary metabolites produced in trace amount on artificial culture media in the laboratory (falavigna et al., 2012). the pure chemical substance of fumonisin is a white hygroscopic material, which is very soluble in water and aqueous solutions of methanol or acetonitrile (bryla et al., 2013; picot et al., 2010). structurally, the fumonisins that belong to the b-series, are characterized by a 20 carbon aminopolyhydroxy-alkyl chain, which is di-esterified with propane-1,2,3tricarboxylic acid (bryla et al., 2013). due to their structural similarity with sphingolipid intermediates (sphinganine and sphingosine), fumonisins can inhibit the enzyme ceramide synthase and disrupt sphingolipid metabolism (wang et al., 1991). sphingolipids are major components of the cell membrane and they are important components of many signaling pathways (wang et al., 1991). contamination of agricultural produce by fumonisin is a growing concern globally, as it causes adverse effects on human and animal health (bryla et al., 2013; picot et al., 2010). upon consumption of contaminated feed, fumonisins may cause a fatal brain lesion known as leucoencephalomalacia in horses (kellerman et al., 1990) and pulmonary edema in pigs (harrison et al., 1990). fumonisins are nephrotoxic, hepatotoxic, carcinogenic and embryohadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 19 issn: 2220-184x toxic in laboratory animals (bryla et al., 2013; gelderblom et al., 1996). in humans, long-term consumption of fumonisin contaminated food has been linked with high incidence of esophageal cancer and it is considered as a risk factor for liver cancer (sun et al., 2007). fumonisin has also been implicated for neural tube defects among populations consuming fumonisin-contaminated maize (missmer et al., 2006). the amount of fumonisin produced varies among f. verticillioides isolates, and not all isolates produce the toxin (alakonya et al., 2008; atukwase et al., 2012; covarelli et al., 2012). the potential of a strain to synthesize fumonisin has been associated with the presence of the fumonisin biosynthesis gene cluster (fum) (proctor et al., 2003). additional genes outside the fum gene cluster are also known to regulate fumonisin biosynthesis, including fcc1, fck1, pac1, zfr1, gbp1, gbb1, cpp1, area, fst1 and fvve1 (picot et al., 2010; sagaram et al., 2006). furthermore, fumonisin biosynthesis by f. verticillioides strains can be affected by environmental factors. prevailing temperature, relative humidity, ph and nutrient status of the substrate on which the fungus grows, have been reported to influence the expression of fum genes and fumonisin production by fusarium strains (picot et al., 2010; sagaram et al., 2006). differences in toxin production profile among f. verticillioides isolates could reveal essential differences in the risk for mycotoxin contamination, with potential implication for human and animal health (proctor et al 2006). considering the great variation in maize genotypes and agroecological conditions in ethiopia (mosisa et al., 2012), f. verticillioides populations are expected to show high variation in fumonisin producing ability. at present, little is known about fumonisins production ability of f. verticillioides isolates in ethiopia. to the best of our knowledge, there has been no research done on this issue in the country before. a good information on fumonisin biosynthesis potential of fungal strains coming from different geographic regions and agroecological zones could help predict the risk of contamination by mycotoxins in these areas. therefore, this study was aimed at examining the total fumonisins (the sum of fb1, fb2 and fb3) production capability of f. verticillioides strains isolated from maize kernels produced under different agroecological conditions in ethiopia. 2. materials and methods 2.1. fungal isolates a total of 80 f. verticillioides isolates, isolated from maize kernel samples collected from 20 major maize growing areas of ethiopia in 2012, were used in this study (fig 1). a total of 200 maize kernel samples of 1 kg size were collected from the 20 different maize growing areas, with 10 randomly selected samples from each area. sampling sites within areas were separated hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 20 issn: 2220-184x at least by 1 km and at most by 5 km from each other. the sample collection areas represented seven major agroecological zones of ethiopia, and their characteristics with respect to elevation, temperature, rainfall and major annual crops are presented in table 1. figure 1. agroecological zones of ethiopia where maize kernels were collected, from which the f. verticillioides isolates were isolated. table 1. summary of characteristics of the agroecological zones of ethiopia where maize kernel samples were collected for isolation of f. verticillioides strains. agroecological zones elevation (masl) a temp (c) b annual rainfall (mm) c major crops d tepid humid mid-highlands (h3) 1600 3000 17 22.5 1800 2200 co, m, w, rt warm moist lowlands (m2) 400 2000 22.5 25 600 1400 s, m, t tepid moist mid-highlands (m3) 1000 3600 17 20 1000 1400 w, t, b, m, pu warm sub-moist lowlands (sm2) 400 2000 20 25 600 1000 s, m, t, fg cool sub-moist mid-highlands (sm4) 2800 4000 15 20 600 1000 b, w, t, pu warm sub-humid lowlands (sh2) 400 2000 22.5 28 1000 1800 s, m, co tepid sub-humid mid-highlands (sh3) 1000 3200 20 22.5 1400 1800 s, m, w, co, rt note: a masl = meters above sea level. b temp = average temperature (>30 years data). c annual rainfall, long-term (>30 years data). d major crops =coffee (co), maize (m), teff (t), wheat (w), sorghum (s), barley (b), finger millet (fg), pulses (pu), roots and tuber crops (rt) (potato, sweet potato, yams, ‘ensete’). (source: moard, 2005). maize kernels were disinfected by soaking in 1% sodium hypochlorite (naocl) for 2 minutes and washed twice in sterile, distilled water. for isolation of fusarium species, maize kernels (fifty kernels from each sample) were placed on petri dishes containing a modified hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 21 issn: 2220-184x czapek-dox iprodione dichloran agar (czid), where the fungicides propiconazole 0.375 mg/l and fenpropimorph 1.125 mg/l were used (halstensen et al., 2006). the petri dishes with maize kernels (five kernels per petri dish) were incubated for 5-7 days at 25°c in the dark. the identity of fusarium colonies was confirmed by first growing on spezieller närstoffarmer agar (sna) for 7-10 days at 20°c under alternating near-ultraviolet (nuv)/white fluorescent light (12 h) and dark (12 h). a spore suspension from the resulting colonies was prepared in sterile water and spread onto water agar (wa) plates for single spore isolation. the plates were incubated at room temperature (22°c) for 16-20 h and single germinating conidia were removed and transferred to new sna plates, containing a filter paper, to obtain monosporic cultures (leslie and summerell, 2006). sub-culturing was made on pda (difco, madison, usa) and carnation leaf agar (cla) plates, incubated at 20c with alternating photoperiod (12 h near uv/white fluorescent light, followed by a 12 h dark period) for 2 – 6 weeks. the morphological identification was performed according to the procedure described by leslie and summerell (2006). for confirmation of morphological identification, sequencing part of the translation elongation factor 1-alpha (ef-1α) gene was done for randomly selected (six) isolates, as described by o’donnell et al. (1998). sequence data were assembled and analyzed using the clc main workbench software 6.9 (aarhus, denmark). the consensus sequences were checked for similarity against the genbank (ncbi-national centre for biotechnology information) and the fusarium-id database. the f. verticillioides isolate mrc826, obtained from the south african medical research council, known as a high fumonisin producer (vismer et al., 2004), was used as a reference isolate. 2.2. preparation of maize kernels substrate to determine the amount of total fumonisins produced by each isolate, autoclaved whole maize kernels of an improved open pollinated maize variety, melkassa-4, obtained from the tigray seed agency, was used as cultivation medium. initially, maize kernels (100 g of kernels and 100 ml of sterile water in 500 ml glass jars) were soaked for one hour and autoclaved at 121°c for one hour (vismer et al., 2004). the moisture level of the maize kernels was measured with a moisture analyzer (perten instruments, model: am5100, sweden) and was approximately 45% at the time of inoculation. 2.3. inoculum preparation and culture growing condition for spore production, each f. verticillioides isolate was sub-cultured by transferring a small (6 mm) disc of mycelia onto a petri-dish containing mung bean agar (mba) (dill-macky, 2003). the plates were incubated at 22°c for 7-10 days, with alternating photoperiod (12 h nuv-light hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 22 issn: 2220-184x followed by 12 h dark periods). conidia of the different f. verticillioides isolates were suspended in sterile water, and the concentration of the conidia was adjusted to 106 conidia/ml after counting the conidial concentration in a kova glasstic slide spore counting chamber. the conidial suspension (1 ml) was inoculated into the maize cultures in 500 ml glass jars. the cultures were incubated in the dark for 4 weeks at 25°c, with brief manual shaking on daily bases during the first two weeks. 2.4. extraction and determination of fumonisin after four weeks of incubation, the culture materials (entire fungal mass and maize substrate) were dried in a forced air incubator at 60°c for three days. the dried samples were finely ground to powder using an ultra-centrifugal mill (zm-200, retsch gmbh & co. kg, germany). the samples were stored at -20°c and thawed at room temperature (22°c) for about 14 hours prior to fumonisins extraction and determination. the extraction was done by thoroughly mixing 5g of the ground samples with 25 ml of 70% methanol using a shaker (1000 rpm) for 3 min. the extract was filtered through a whatman no. 1 filter paper and the collected filtrate was used in determining the total fumonisins using an enzyme linked immunosorbent assay (elisa) kit (ridascreen®fumonisin, r-biopharm ag, darmstadt, germany), according to the manufacturer’s instructions. analysis of the results of ridascreen® enzyme immunoassay was done using rida®soft win software (art. nr. z9999, rbiopharm ag, darmstadt, germany). fumonisins concentrations above the highest standard were further diluted, and the results obtained were multiplied by the dilution factor. the minimum limit of detection for the kit was 0.025 mg/kg, and all the samples were analyzed and recorded in duplicate wells. 2.5. statistical analysis statistical analysis for comparison of fumonisin levels produced by the f. verticillioides isolates per maize growing area and agroecological zone were performed with one-way anova using spss (2013) version 22 (ibm spss statistics 22, armonk, new york). one sample t-test was used to compare the mean levels of total fumonisins produced by the test isolates and the south african reference isolate (mrc826). differences in fumonisin production ability between the test isolates and the south african reference isolate were also computed using microsoft excel (2013). descriptive statistics were used to present the mean, median, quartiles, minimum and maximum fumonisins levels per agroecological zones. all statistical test were performed at a probability level of p = 0.05. hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 23 issn: 2220-184x 3. results total fumonisins produced by f. verticillioides isolates from maize kernels grown in ethiopia are presented in table 2. fumonisins were detected in cultures of all the 80 f. verticillioides isolates evaluated. there was variation in the quantity of total fumonisins produced by the isolates evaluated and ranged from 0.25 to 38 mg of the toxin per kg of culture material (fungal biomass and maize kernels). isolates collected from the same area as well as from different areas varied in the level of the toxins produced in the culture medium. isolate sr-6952, collected from sire area had produced the highest concentration of total fumonisins (38 mg/kg), while isolates sr-3133 and sr-6351 collected from the same area had produced very low levels of total fumonisins (0.66 mg/kg and 1.82 mg/kg, respectively). similarly, varying ranges in fumonisin concentration were observed among isolates collected from the other areas as well (table 2). table 2. levels of total fumonisins produced in vitro by f. verticillioides isolated from maize kernels grown in ethiopia. isolate name source area fumonisins (mg/kg) a isolate name source area fumonisins (mg/kg) a ag-122 agaro 1.82 aw-412 hawassa 10.42 ag-131 agaro 10.29 j-332 jimma 8.40 ag-411 agaro 1.26 j-512 jimma 18.88 ag-431 agaro 34.86 j-541 jimma 23.22 ag-6632 agaro 5.87 j-6811 jimma 0.71 ab-6921 alaba 4.61 km-131 kemmisse 4.94 ab-6821 alaba 1.95 km-142 kemmisse 2.79 ab-522 alaba 10.14 km-313 kemmisse 27.9 al-6111 alamata 35.91 km-322 kemmisse 6.83 al-4432 alamata 1.87 km-351 kemmisse 4.32 al-3443 alamata 1.87 kr-231 korem 24.80 al-6811 alamata 1.71 kr-252 korem 11.87 al-5843 alamata 11.23 kr-6743 korem 3.129 am-212 ambo 1.36 mc-212 maichew 1.38 am-6552 ambo 2.73 mc-234 maichew 12.68 am-6444 ambo 24.8 mc-422 maichew 12.22 ar-212 dedessa 24.96 mc-112 maichew 1.95 ar-6441 dedessa 22.88 mc-431 maichew 33.81 ar-312 dedessa 9.60 ml-313 melkassa 1.71 bk-1122 bako 0.60 ml-6341 melkassa 1.82 bk-2734 bako 8.64 ml-6533 melkassa 1.97 bk-6521 bako 31.29 ml-6842 melkassa 0.25 bk-3741 bako 11.34 nk-112 nekemte 9.42 bd-112 bedele 1.57 nk-242 nekemte 23.68 bd-331 bedele 0.95 nk-432 nekemte 10.24 bd-413 bedele 1.14 nk-6232 nekemte 1.62 bd-422 bedele 1.03 nk-6633 nekemte 25.60 ds-121 dessie 0.99 s-3133 sire 0.66 hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 24 issn: 2220-184x ds-132 dessie 2.16 s-322 sire 22.88 ds-322 dessie 0.92 s-6351 sire 1.82 ds-693 dessie 37.38 s-6952 sire 38.01 gd-6351 gedeo 10.27 ws-112 welayta-sedo 3.32 gd-6531 gedeo 2.67 ws-6232 welayta-sedo 1.70 g-112 gibe 7.84 ws-121 welayta-sedo 4.56 g-421 gibe 33.54 ws-6332 welayta-sedo 23.20 g-61011 gibe 30.08 z-111 ziway 34.02 g-6331 gibe 14.09 z-311 ziway 1.77 aw-121 hawassa 18.48 z-6812 ziway 4.31 aw-222 hawassa 34.10 z-512 ziway 5.96 aw-231 hawassa 18.88 mrc-826 south africa 95.5 aw-314 hawassa 1.33 * note: a fumonisins concentrations presented in mg/kg culture material (fungal biomass and maize kernel). * fumonisins concentration in the control culture was <0.025 mg/kg. table 3. summary of total fumonisins produced by f. verticillioides strains isolated from maize kernels grown in different areas and agroecological zones in ethiopia. isolate sourcearea agroecological zone a number of isolates tested fumonisins levels (mg/kg) range mean ± sem b agaro sh3 5 1.26 – 34.86 10.8 ± 6.2 alaba sh3 3 1.95 – 10.14 5.6 ± 2.4 alamata sm2 5 1.22 – 35.91 10.5 ± 6.6 ambo m3 3 1.36 – 24.80 9.6 ± 7.6 bako sh3 4 0.60 – 31.29 13.0 ± 6.7 bedele h3 4 0.95 – 1.57 1.2 ± 0.1 dedessa m2 3 9.06 – 24.96 19.0 ± 4.8 dessie m3 4 0.92 – 37.38 10.4 ± 9.0 gedeo m3 2 2.67 – 10.27 6.5 ± 3.8 gibe sh2 4 7.84 – 33.54 21.4 ± 6.2 hawassa m3 5 1.33 – 34.10 16.6 ± 5.4 jimma h3 4 0.71 – 23.22 12.8 ± 5.1 kemmisse m2 5 2.79 – 27.90 9.4 ± 4.7 korem sm4 3 3.13 – 24.80 13.3 ± 6.3 maichew sm4 5 1.38 – 33.81 12.4 ± 5.9 melkassa sm2 4 0.25 – 1.97 1.5 ± 0.4 nekemte sh3 5 1.62 – 25.60 14.0 ± 4.6 sire sh3 4 0.66 – 38.01 15.8 ± 9.0 welayta-sedo sh3 4 1.70 – 23.20 8.2 ± 5.0 ziway sh3 4 1.77 – 34.02 11.5 ± 7.6 mrc826 1 95.5 95.5 uninoculated control <0.025 <0.025 note: a agroecological zonesh3: tepid humid mid-highlands; m2: warm moist low-lands; m3: tepid moist mid-highlands; sh2: warm sub-humid low-lands; sh3: tepid sub-humid mid-highlands; sm2: warm sub-moist low-lands; sm4: cool sub-moist mid-highlands (source: moard, 2005) b sem: standard error of means, mean fumonisins levels produced by f. verticillioides isolates did not differ statistically (p>0.05) between maize growing areas. table 3 shows the summary of total fumonisins produced by f. verticillioides isolates collected from different areas in ethiopia. although it was not statistically significant (p>0.05), hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 25 issn: 2220-184x the mean fumonisins levels produced by isolates from gibe, dedessa, and hawassa were higher than the levels produced by isolates obtained from the other areas. for isolates from gibe, the fumonisin levels ranged from 7.84 to 33.54 mg/kg (mean value: 21.4 mg/kg), isolates from dedessa ranged from 9.6 to 24.96 mg/kg (mean value: 19 mg/kg) and isolates from hawassa produced 1.33 to 34.1 mg/kg fumonisin, with mean value 16.6 mg/kg. on the other hand, isolates from bedele and melkassa produced very low amounts of fumonisins. fumonisin production by isolates from bedele ranged from 0.95 to 1.57 mg/kg (mean value: 1.2 mg/kg), whereas those from melkassa varied from 0.25 to 1.97 mg/kg with mean value of 1.5 mg/kg. table 4. summary of total fumonisins produced by f. verticillioides isolates isolated from maize kernels grown in ethiopia in relation to some critical values set by the codex alimentarium commission (cac, 2014) and concentrations compared to a reference isolate from south africa. fumonisin levels (mg/kg) a number of isolates proportion from total isolates differences with reference isolate (%) b >20 20 25 60.0 76.0 >4 46 57.5 60.0 95.5 <2 28 35 98.0 99.7 above detection (>0.025) 80 100 p-value 0.001 note: a fumonisin level 4 mg/kg is the maximum tolerable fumonisins level in unprocessed raw maize grain, and 2 mg/kg is the maximum level in maize flour and meal based on the codex alimentarium commission (cac, 2014). b percentage difference in levels of total fumonsins produced by the test isolates compared to the reference isolate (mrc826) computed on microsoft excel, while one sample t-test statistical analysis is performed using spss. total fumonisins produced by the f. verticillioides isolates were compared with some critical values recommended by the codex alimentarium commission in maize for human consumption (cac, 2014), as presented in table 4. of all the isolates tested in this study, 57.5% produced total fumonisins in concentrations at >4 mg/kg, which is above the maximum tolerable limit in unprocessed maize recommended by the joint fao/who codex committee on contaminants in foods (cac, 2014). the total fumonisins levels produced by some of the f. verticillioides isolates was quite low, with 35% of the isolates producing fumonisins levels at <2 mg/kg. only 25% of the isolates produced fumonisins at >20 mg/kg. one sample t-test analysis revealed that all the f. verticillioides isolates showed significantly lower (p<0.001) fumonisins production level than the south-african reference isolate (mrc826). observed differences were in the range of 60%-99.7% compared to the reference isolate (table 4). figure 2 shows total fumonisins levels produced by the f. verticillioides isolates collected from different agroecological zones of ethiopia, presented in box and whisker plot, hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 26 issn: 2220-184x depicting the median, mean, quartiles, the minimum and maximum values. when the data were combined and analyzed according to the agroecological zones of ethiopia, the highest mean total fumonisins production was observed in isolates originating from the warm sub-humid lowlands (21.4 mg/kg), followed by isolates from the warm moist-lowlands (13 mg/kg) (fig 2). isolates from the warm sub-moist lowlands produced the lowest amount of fumonisin (mean 6.4 mg/kg). figure 2. box and whisker plot showing levels of total fumonisins produced by f. verticillioides isolates isolated from maize kernels grown in different agroecological zones of ethiopia. boxes represent the interquartile range between the first and third quartiles (25th and 75th percentiles, respectively) and the horizontal line inside denotes the median. whiskers denote the minimum and maximum observations. circular dotes denote mean fumonisins values. data from 20 areas are summarized into their respective agroecological zones. (note: aagroecological zonesh3: tepid humid mid-highlands; m2: warm moist lowlands; m3: tepid moist mid-highlands; sh2: warm sub-humid lowlands; sh3: tepid sub-humid mid-highlands; sm2: warm sub-moist lowlands; sm4: cool submoist mid-highlands (source: moard, 2005)). 4. discussion the present study revealed a widespread occurrence of fumonisins producing f. verticillioides in maize in ethiopia, as all the 80 isolates evaluated produced fumonisins. these findings agree with the report of reyes-velázquez et al. (2011) in mexico, who stated that all f. verticillioides isolates obtained from different maize hybrids able to produce fumonisins. likewise, all f. verticillioides isolates, grown on sterile rice grain, evaluated in brazil by de oliveira rocha et al. (2011) produced fumonisin b1. in contrast, covarelli et al. (2012) reported fumonisins producing ability of 25 f. verticillioides isolates in italy and 20% of them did not produce hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 27 issn: 2220-184x detectable level of fumonisins, despite of containing the fum gene cluster. this was explained to mutation or altered expression of the fum gene clusters. in kenya, alakonya et al. (2008) observed that 26% of the f. verticillioides isolates did not produce detectable level of fumonisin in maize cultures. however, they were only considered the quantification of fumonisin fb1 instead of total fumonisins as in the present study. a wide-range of variation in total fumonisins production among f. verticillioides isolates was observed in this in vitro study. the detected variation in fumonisin production among isolates could be due to variations in the inherent genetic characteristics of the isolates. previous molecular studies of f. verticillioides isolates revealed a positive relationship between the fum gene cluster and fumonisin production (picot et al., 2010; sagaram et al., 2006). the amount of transcription products from the key fum genes, fum1, fum6, fum8 and fum21 positively correlates with fumonisin accumulation, but disruption of these genes results in significant reduction in fumonisin production (proctor et al., 2003; sagaram et al., 2006). isolates with functionally active fum genes may produce higher total fumonisins (fb1+fb2+fb3) than other isolates that can only produce either of the fb types. a high level of sequence variation inside the fum gene cluster can also explain for inter and intraspecific variation in fumonisin production by fusarium species (stępień et al., 2011). the occurrence of high fumonisins concentration producing isolates, compared to others across all the areas investigated, demonstrated that the distribution of fumonisins producing f. verticillioides strains is not linked to specific geographic regions. potent strains appeared widespread and uniformly distributed all over the maize growing areas. the reason for the highest mean total fumonisins observed in isolates originating from the warm sub-humid lowlands may be due to selection of high fumonisin producing strains by chance from this agroecological zone. the observed variation in fumonisin production by f. verticillioides isolates obtained from the same geographical areas was in accordance with the results obtained elsewhere (alakonya et al., 2008; covarelli et al., 2012; de oliveira rocha et al., 2011). the levels of fumonisins observed in this study were lower compared to those reported in uganda (19.4 – 99.8 mg/kg) (atukwase et al., 2012), in south africa (1500 4200 mg/kg) (vismer et al., 2004), in italy (1 – 115 mg/kg) (covarelli et al., 2012) and in mexico (24.5 – 7190 mg/kg) (reyes-velázquez et al., 2011). however, reyes-velázquez et al. (2011) used higher inoculum concentrations (107 spores/ml) compared to the current study. depending on the criteria of nelson et al. (1991), f. verticillioides strains can be categorized into three groups, high fumonisins producers (above 500 mg/kg), intermediate (50 to 500 mg/kg) and low producers (trace to 49 mg/kg). based on the above criteria, all of the hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 28 issn: 2220-184x strains isolated from maize kernels and evaluated in this study were probably low fumonisins producers. total fumonisins levels produced by a substantial proportion of the f. verticillioides isolates tested in the current study were above the maximum limit that is considered unsafe for human consumption. the maximum tolerable levels of total fumonisins (fb1+fb2+fb3) recommended by the joint fao/who expert committee on food additives (jecfa) are 4 mg/kg in raw maize and 2 mg/kg in maize flour and meal (cac, 2014). the widespread existence of isolates producing fumonisin levels above the maximum tolerable limit indicates a potential risk for food safety. this should not be underestimated taking into consideration the fact that f. verticillioides is the most frequently isolated fusarium species in maize kernels (amare ayalew, 2010; hadush tsehaye et al., 2016). the concentrations of fumonisins produced may become higher when stressful environmental conditions prevail, which are more suitable for fumonisins synthesis. climate change effects such as increased temperature and limited water availability, may stress host plants and favor growth of mycotoxigenic f. verticillioides strains. 5. conclusion the results revealed that fumonisins producing f. verticillioides strains occur across all maize growing areas in ethiopia. although the concentrations produced by some of the isolates in the current study were generally low, the widespread occurrence of fumonisins producing strains, capable of producing the toxin above the maximum tolerable levels, in maize intended for human consumption indicates a possible food safety risk. thus, efforts should be made to prevent the spread of this toxigenic fungus as well as to develop sound management practices including implementation of good agricultural practices and explore all possible ways to avoid maize contamination with fumonisins. it is also very important to prevent introduction of more toxigenic strains with import of germplasms from abroad. 6. acknowledgments this study was financially supported by the norwegian agency for development cooperation (norad) via the inter university collaboration between mekelle university (mu), hawassa university (hu) and the norwegian university of life sciences (nmbu) through the muhu-nmbu project. the authors wish to thank dr. hester f. vismer (south african medical research council) for supplying the reference isolate (mrc826). hadush, t., leif, s., arne, t., may, b. b., dereje, a and anne, m. t (mejs) volume 15(1):17-31, 2023 © cncs, mekelle university 29 issn: 2220-184x 7. conflict of interest there is no conflict of interests. 8. reference alakonya, a., monda, e & ajanga, s. 2008. variation in in vitrofumonisin b1 production by differentfusarium verticillioides isolates in kenya. american-eurasian journal of agriculture and environmental sciences, 4: 368-371. amare ayalew 2010. mycotoxins and surface and internal fungi of maize from ethiopia. african journal of food, agriculture, nutrition and development, 10: 4110-4122. atukwase, a., muyanja, c & kaaya, a.n. 2012. potential for fumonisin production by the strains of gibberella fujikuroi species complex isolated from maize produced in uganda. journal of biological sciences, 12: 225-231. bryła, m., roszko, m., szymczyk, k., jędrzejczak, r., obiedziński, m.w & sękul, j. 2013. fumonisins in plant-origin food and fodder-a review. food additives and contaminantspart a, 30: 1626-1640. cac. 2014. report of the eighth session of the codex committee on contaminants in foods. codex alimentarius commission (cac). geneva, 14 -18 july 2014. available at: http://www.codexalimentarius.org, downloaded 13 august 2016. covarelli, l., stifano, s., beccari, g., raggi, l., lattanzio, v.m.t & albertini, e. 2012. characterization of fusarium verticillioides strains isolated from maize in italy: fumonisin production, pathogenicity and genetic variability. food microbiology, 31: 1724. de oliveira rocha, l.d., reis ,g.m., da silva, v.n., braghini, r., teixeira, m.m.g & correa, b. 2011. molecular characterization and fumonisin production by fusarium verticillioides isolated from corn grains of different geographic origins in brazil. international journal of food microbiology, 145: 9-21. dill-macky, r. 2003. inoculation methods and evaluation of fusarium head blight resistance in wheat. in: leonard k. j. and bushnell w. r. 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