CONTACT : ODO JOEL INYA odojoel@gmail.com 79 Abstract Environment pollution is a bur ning topic of the day. Air, water and soil are being polluted alike. Soil being a "universal sink" bears the greatest burden of environmental pollution. It is getting polluted in a number of ways. There is urgency in controlling the soil pollution in order to preserve t he soil fertility and increase the productivity. In this re search work, the microbial and physioche mical assessment of soil contaminated with cassava waste water were studied using standard-based method and standard analytical methods. A total of 6 soil sample s were obtained from Naka road, North bank and Gboko road. Three of the soil samples were contaminated with cassava waste water and the remaining three soil samples were used a s control. The isolation a nd enumeration of micr obial population was carried out using standard-ba sed methods. Standard analytical methods were used to assay for physicoc hemical properties. T he highest bacterial count of 3.40x103 , 2.85x103 and 2.70x103 CFU/g for Naka road, Gboko r oad and North bank respectively w hile for uncontaminated soil were 4.70x104 , 2.90x104 and 2.70x104 CFU/g for North bank Naka road, and Gboko road respectively. There is significant difference in the total viable count between c ontaminated and uncontaminated (P<0.05). The fungal counts for the polluted and c ontrol soil ranged from fungi count 1.16 x 103 ±5.70 x 101 to 1.4×103±2.82×103 CFU/g, re spectively. The fungal counts were significantly lower tha n the bacterial counts (p < 0.05). The bacteria isolates were pseudomonas spp, Bacillus spp, Micrococcus spp, Klebsiella spp, Escherichia coli, Staphylococcus spp, and Proteus spp and for the fungi isolates were Aspergillus spp, Geotrichum spp, Mucor spp and Rhizopus spp. The pre sent study shows that the cassava effluent can have an increasing or limiting effect on the microbial diversity of the polluted soil which could also be attributed to the simultaneous impact on the physicochemical parameters of the soil. Therefore the release of Cassava waste water into the environment should be disc ouraged; processor should be traine d on simple treatment technique on e fflue nts that will make it less harmful to the environment. And there nee d for public awareness on the danger of releasing effluents into the environment. ISSN : 2580-2410 eISSN : 2580-2119 Microbial and Physicochemical Assessment of Soil Contaminated with Cassava Waste Water in Makurdi Metropolis Ebah Esther Eneyi 1, Odo Joel Inya 2*, Obochi Irene Ijakuwa 1 1 Department of Fisheries and Aquaculture University of Agriculture, Makurdi, Nigeria. 2 Departments of Microbiology, University of Agriculture, Makurdi, Nigeria . OPEN ACCESS International Journal of Applied Biology Keyword Cassava; Physicochemical; Microbial; Contamination Article History Received April 4, 2022 Accepted December 14, 2022 International Journal of Applied Biology is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly c ited. International Journal of Applied Biology, 6(2), 2022 80 Introduction Environment pollution is a burning topic of the day. Air, water and soil are being polluted alike. Soil being a "universal sink" bears the greatest burden of environmental pollution. It is getting polluted in a number of ways. There is urgency in controlli ng the soil pollution in order to preserve the soil fertility and increase the produc tivity. Polluti on may be defined as an undesirable change in the physical, chemical and biological characteristics of air, water and soil which affect human life, lives of other useful living plants and animals, industrial progress, living conditions and cultural assets. A pollutant is something which adversely interfers with health, comfort, property or environment of the people. Generally most pollutants are introduced in the envi ronment by sewage, waste, accidental discharge or else they are by-products or residues from the production of something useful. Due to this our precious natural resources like soil, water and air are getting polluted (Mohammed et al., 2014) Microorganisms are very small forms of life that can sometimes live as single cells, although many also form colonies of cells. A microscope is usually needed to see individual cells of these organisms. Many more microorganisms exist in topsoil, where food sources are plentiful, than in subsoil. They are especially abundant in the area immediately next to plant roots called the (rhizosphere), where sloughed-off cells and chemicals released by roots provide ready food sources. These organisms are primary dec omposers of organic matter, but they do other things, such as provide nitrogen through fixation to help growing plants, detoxify ha rmf ul chemicals (toxins), suppress disease organisms, and produce products that might stimulate plant growth. Soil microorganisms have had another di rect importance for humans —they are the source of most of the antibiotic medicines we use to fight diseases (Fred and Harold, 2009). Soil microorganisms can be grouped into bacteria, actinomycetes , fungi, algae, protozoa, and nematodes. Apart from the dead plant or ani mal residues in soils, Soil Organic Manure is composed of a significant content of living microorganisms and their dead fractions. The humus fraction is resistant to microbial decomposition and persists for thousands of years contri buting to the long -lived carbon pool in soils. Soil microorganisms are involved i n the decomposition of soil organic matter, and the rate of decomposition depends both on the nature of microorganisms in soil and the nature of organic matter sources. Enhancing the activities of soil fungi has been recognized as one of the potential options for reducing Soil Organic Carbon turnover, thereby increasing carbon sequestration. Melanin, chitin, and glomalin are examples of fungal-derived recalcitrant residues that tend to exist for a long time in soils. Apart from the humification process, soil microorganisms are involved in mineralization of Soil Organic Manure, thereby resulting in the loss of carbon from soils (Thangavel et al., 2019). Cassava (ManihotesculentaCrantz, synonymous with ManihotutilissimaRhol) belongs to the family Euphorbiaceae. The tubers are quite rich in carbohydrates (85 -90%) wi th a very small amount of protein (1.3%) in addition to cyanogenicgluc oside (Linamarin and Lotaustiallin) which are present in cassava (Nwabueze and Odunsi, 2007). This high carbohydrate content makes cassava a major food item especially for the lower income earners in most tropical countries especially Africa and Asia (Dess e and Taye, 2001). Cassava is a starchy food for more than 300 million people in many tropical countries of the world. Cassava food products are the most important staples of rural and urban household in Southern Nigeria. In Nigeria, traditional foods processed at home in small scale cottage operation constitute the principal mode of utilization of cassava (Inges, 1982). International Journal of Applied Biology, 6(2), 2022 81 It is generally believed to have originated from Brazil in South America. Cassava has spread to many other tropical countries like West Indians, South East Asia, and other West Africa, especially in Nigeria, Sierra Leone and Liberia. In Nigeria, cassava is extensively cultured and classified into two kinds: namely Sweet cassava ( Manihotesculenta) and Bitter cassava (Manihotutilisssima). Bitter cassava contains glucoside which forms hydrocyanic acid during processing. Hydrocyanic acid can be removed by cooking or fermenting in water for specific period. There are varieties of cassava which differ significantly in their colour, stem and period of maturity (IITA, 2011). Cassava processing plant also known as cassava mill was invented in 1919 and planted in 1934 and is extensively used in Nigeria, especially in the southern part where cassava is a major agricultural produce. It is used to grind peeled cassava tubers which are drained for 2-4 days and then baked over fire in pans to produce Garri - a major staple food (FAO, 2006). The edible tubers are processed into various forms which include chips, pellets, cakes and flour. The flour could be fried to produce Garri or steeped in water to ferment and produce fufu when c ooked (Oyewole and Afolami, 2001). The produc tion and consequent consumption of cassava have increased extensively in recent times. The increased utilization of processed cassava products has increased the environmental pollution associated with the disposal of effluents. The highly offensive odour emanating from the fermenting effluent calls for regulation in the discharge of waste generated (Akanniet al., 2006). In most areas, cassava mills are mainly on small scale basis, owned and managed by individuals who have no basic knowledge of environmental protection. Though on small scale basis, there are many of them, which when put together, create enormous impact on the environment. C assava also contains much pollutant such as disease causing pathogens e.g. bacteria and fungi. Disposal of agricultural by -products such as cassava waste from processing activities is a concern in Nigeria. There is an appreciable high level of contami nation arising from the discharge of effluents on agricultural soil hence the need for proper treatment before discharge and conversion of these cassava wastes into biosorbent that can remove toxic and valuable metals from the effluent. Effluent is a liquid or solid waste, especially chemicals produced by factories or from agricultural products or domestic waste. Effluents usually contain a wide variety of chemicals, debris and various microorganisms which are mostly emptied on soil or carried away through special underground pipes called Sewers. Types of effluents include industrial effluent, agricultural effluents, domestic effluent and storm effluent (Cheesbrough, 2005). The aim of this study is to determine the Microbial and Physiochemical assessment of soil contaminated with cassava waste water in Makurdi Metropolis, Benue State. Materials and Methods Study Area This study was carried out in Makurdi Local Government Area. Makurdi local Government Area has a population of 300,000 persons (NPC, 2006), and lies between latitudes 7º40¹N and 7º53¹ N of the equator, and between longitudes 8º22¹E and 8º35¹E of Greenwich Meridian. It is a163km radius circle, covering 804km² land mass. Climatically, Makurdi falls within the tropical, sub-humid, wet and dry climate which has two distinct seasons, namely wet and season and dry season. The wet season starts from April and lasts till October, while the dry season starts in November and lasts till March. Rainfall ranges from 775 millimeters to1792 millimeters, with a mean a nnual value of 1190 millimeters. International Journal of Applied Biology, 6(2), 2022 82 Sampling Techniques A total of 6 soil samples were obtained from Naka road, North bank and Gboko road. Three of the soil samples were contaminated with cassava waste water and the remaining three soil samples were used as control. The samples were collected using sterile containers and were transported to the laboratory for analysis. Chemicals and reagents Nutrient agar, Macconkey agar, Potato dex trose agar (PDA), distilled water, Acetone, Simon’s citrate agar, Urea agar, peptone water, hydrogen peroxide, lacto phenol cotton blue, and picric acid. Equipments, Apparatus and instruments Weighing balance, Test tubes and test tube rack, wire loop, Heating mantle, conical flask, Petri dish, pH meter, Sprayer, measuring Cylinder, Aluminum Foil, Spectrophotometer, Syringe, Incubator, pressure pot, Sample Bottle, Spirit La mp, Cotton wool, Microscope and microscope slide. Enumeration of Total Heterotrophic Bacteria and Fungi Samples of the polluted soil were serially diluted in ten fol ds. Total viable heterotrophic aerobic counts were determined by plating in duplicate using pour plate technique. T hen the molten nutrient agar, eosin methylene blue agar at 45 0C and was potato dextrose agar was poured into the petri dishes containing 1mL of the appropriate dilution for isolation of the total heterotrophic bacteria and fungi, coliforms and Escherichia coli respectively. They were swirled to mix and colony count was taken after i ncubating the plates at 300C for 48hrs and culture growth was preserved by sub culturing the bacterial isolates into nutrient agar slant which was used for biochemical tests. Characterization and Identification of Bacterial and Fungal Isolates Bacterial isolates were characterized and identify after studying their Gram reaction as well as cell micro morphology. Other tests like spore formation, motility, and catalase production. Citrate utilization, oxidative/fermentative utilization of glucose, indole production, methyl red-Voges Proskauer reaction, urease and coagulase production, starch hydrolysis, production of H2S from tri ple sugar iron (TSI) agar and sugar fermentation were carried out according to the methods described by Ochei and Kolhatkar (2008) . Fungal isolates were examined macroscopically and microscopically using the needle mounts technique. Their identification was performed according to the scheme of APHA (2005). Determination of the Physicochemical Parameters A number of physicochemical parameters of the contaminated soil samples were determined. These include pH, conductivity, nitrate, phosphate, sulphate, oil content and exchangeable cations. The pH was measured using pH meter; conductivity was measured using conductivity meter. Sulphate, nitrate and phosphate were determined using Barium chloride (Turbid metric), Cadmium reduction and Ascorbic acid methods respectively. All analyses were in accordance with APHA (2008). International Journal of Applied Biology, 6(2), 2022 83 Biochemical Tests Catalase test: This test was carried out to determine the ability of the test organism to produce enzyme that breaks down hydrogen peroxide to oxygen and water. A drop of hydrogen peroxide was added to the growths isolated on the subculture plate and observation was made after 10-20 seconds. Observation of white bubbles confirms positive, while no bubbles with original color gives negative result (Cheesbrough, 2005). Urease test: This test was done to determine the ability of the test organism to produce enzyme urease, which breaks down urea to ammonia and carbon dioxide. 2ml of urea agar was measured in to a sample bottle, slanted and allow cooling and jelling to occur. The test organism was collected, inoculated on the medium and incubated for 24 hour, after which a pink color was observed for positive and no color change for negative (Cheesbrough,2005). Indole test: This test was done to differentiate Gram negative bacilli. 2ml of peptone water was dispensed in to a sterilized sample bottle and the test organism was inoculated. This was incubated for 24-48 hours at 35-370c after which 0.2ml of Kovac’s reagent was added and mixed. A positive test gives pink coloration at the top of the medium, while no color change is an indicative of negative test (S, 2000). Citrate test: This test was carried out to determine the ability of the test organism to utilize citrate as its sole source of carbon. Si mon’s citrate agar medium was dispensed in a sample bottle and sterilize for 15 minutes at 1210C. The organism was collected and inoculated incubated for 24 hours at 370C. Microscopy: After 48 hours of incubation the suspended organisms were seen and were used to prepared smears on clean slides. The slides was cleaned with alcohol, the test organism was placed on each of the clean slides using a sterilized wire l oop and each slide were stained with lactophenol for about 1 minutes. The slide was subjected to the observation of the suspected organism under oil immersion objective lens (x100) of a bright field microscope (Baseyet al., 2000). Results The mean viable, coliform and fungi count of soil samples contaminated with cassava waste water as presented in Table 1, the total heterotrophic bacteria and fungi count range from 2.70 x 103±8.49 x 102 to 3.4×103±8.49×103 CFU/g and fungi count 1.16 x 103 ±5.70 x 101 to 1.4×103±2.82×103 CFU/g. Control soil on the other hand ranges from 2.70 x 104±1.56 x 103 for Gboko road to 4.0×104 ±2.83×103 CFU/g for Naka road samples and 2.5×104 ±7.49×103 CFU/g typically there is significant variation(p<0.05). Table 2, presents the prevalence of isolates across locations. Table 3, presents the cultural morphology and biochemical characteristics of bacteria isolates. Seven genera of bacteria were identified in this study Pseudomonas spp, Klebsiella spp, Bacillus spp, Escherichia coli, Staphylococcus spp, and Proteusspp. Table 4, presents the morphology and characteristics of fungi isolates. Four (4) genera of fungi were identified in this study: Aspe rgillus spp, Geotrichum spp, Mucor spp and Rhizopus spp. Table 5, presents the physicochemical parameter of soil samples which were; Temperature, Soil pH, Colour and Texture. International Journal of Applied Biology, 6(2), 2022 84 Table 1. Total Viable, Coliform and Fungi Count of Samples from the Study Locations Location TVC TCC TFC Naka Road 3.40 x 103 ±8.49 x 102b 1.60 x 103 ±8.49 x 102b 1.16 x 103 ±5.70 x 101c North bank 2.70 x 103±8.49 x 102b 2.00 x 103 ±1.13 x 103b 3.00 x 103±1.69 x 103c Gboko Road 2.85 x 103 ±3.54 x 102b 2.15 x 103 ±4.94 x 103b 1.40 x 104±2.82 x 103b Control( Naka Road) 2.90 x 104±9.90 x 103b 4.90 x 104±1. 41 x 103a 1.90 x 103±4.29 x 102c Control( Naka Road) 4.00 x 104±2.83 x 103a 5.95 x 104±1.20 x 104a 2.50 x 104±7.49 x 103a Control( Gboko Road) 2.70 x 104±1.56 x 103a 5.40 x 104±2.82 x 104a 1.22 x 104±1.13 x 103a P- Value 0.008 0.001 0.002 Table 2. Prevalence of Isolates across Locations Isolates L1 L2 L3 C1 C2 C3 Total Pseudomonas spp 0(0.00) 0(0.00) 0(0.00) 1(1.56) 2(3.13) 1(1.56) 4(6.35) Bacillus spp 1(1.56) 1(1.56) 2(3.13) 3(4.69) 1(1.56) 2(3.13) 10(15.63) Micrococcus 0(0.00) 1(1.56) 0(0.00) 1(1.56) 2(3.13) 1(1.56) 5(7.81) Klebsiella spp 0(0.00) 1(1.56) 0(0. 00) 2(3.13) 3(4.69) 2(3.13) 8(12.50) Escherichia coli 1(1.56) 0(0.00) 1(1.56) 1(1.56) 1(1.56) 0(0.00) 4(6.35) Staphylococcus specie 1(2.86) 1(2.86) 0(0.00) 2(5.71) 0(0.00) 1(2.86) 5(7.81) Proteus spp 0(0.00) 0(0.00) 1(1.56) 1(1.56) 2(5.71) 1(1.56) 5(7.81) Aspergillus spp 1(1.56) 0(0.00) 1(1.56) 1(1.56) 1(1.56) 1(1.56) 5(7.81) Geotrichum spp 0(0.00) 1(1.56) 0(0.00) 2(5.71) 1(1.56) 0(0.00) 5(7.81) Mucor spp 0(0.00) 0(0.00) 0(0.00) 1(1.56) 0(0.00) 1(1.56) 4(6.35) Rhizopus 2(5.71) 1(1.56) 2(5.71) 2(5.71) 2(5.71) 3(4.69) 2 (3.13) Total 6(9.38) 6(9.38) 7(10.94) 17(26.56) 15(23.44) 13(20.31) 64(100) Key: L1 – Naka Road L3 – Gboko Road C2- Control 2 s pp-s peci es L2 - North Bank C1- Control 1 C3- Control 3 International Journal of Applied Biology, 6(2), 2022 85 Table 3. Morphology and Biochemical Characteristics of Bacteria Isolates. Colony colour Colony shape Morphology Gram’s reaction Cat Cit Urease Indole Oxidase H2S Suspected organisms Cream Ci rcul ar Cocci + + + - - - - Staphylococcus s pp Green Metal l i c Sheen Ci rcul ar Rod - + - - + - - Escherichia col i Yel l ow Ci rcul ar Rod + + + - - - - Micrococcus s pp Mucoi d Ci rcul ar Rod - + - + - - - Klebsiella s pp Green Ci rcul ar Rod - + + - - + - Pseudomonas s pp Pal e Ci rcul ar Rod - + + + - - + Proteus s pp Whi te Irregul ar Rod + + + - - - - Bacillus s pp Key: H2S- Hydrogen Sul phi de Ci t- Ci trate uti l i zati on Cat- Catal as e producti on Rxn- Reacti on Table 4. Macroscopic and Microscopic Characteristics of Fungi Macroscopic Microscopic Fungi isolates Velvety filamentous white growth that sporulates black powdery spores Long septate with conidiophores bearing brown spores and phialide at its apex Aspergillus spp Whitish smooth circular and raised colony or growth Presence of arthrospore spores with rounded end Geotrichum spp White and wooly aerial growth that darkens as its sporulates Non-septate hyphae with straight sporangiophore with many spherical spores. mucor spp Long hyphael growth which sporulated within two days to turn to black spore Non-septate, branched mycelium with round shaped sporangia Rhizopus spp Key: s pp – s peci es Table 5. Physicochemical Parameters Sample Temperature(ºc) Soil pH Colour Texture Naka road 28 8.0 Brown Silt North bank 29 7.0 Dark-brown Coarse Gboko Road 25 7.5 Dark fine Control soil 1 30 8.2 Brown Silt Control soil 2 32 8.5 Dark-brown x Coarse Control soil 3 31 8.4 Dark Fine International Journal of Applied Biology, 6(2), 2022 86 Discussion Environment pollution is a burning topic of the day. Air, water and soil are being polluted alike. Soil being a "universal sink" bears the greatest burden of environmental pollution. (Mohammed et al., 2014). The impact of Cassava waste water on the physiochemical and microbial quality of the soil around Cassava processing zone constitute great concern as it alters the natural environment. This effluent is released indiscriminately into the environment without any form of treatment. This activity of Cassava processor has serious impact on the soil as these effluents contain chemical that may affect the biotic components of the soil. The result of this study reveal that the Microbial population (Total viable count, total coliform count and total fungi count) reduced significantly in soil contaminated with Cassava effluent when compa red with control soil from the same area, although thi s contra dict the findings of Igbinosa and Igiehon (2015) whose findings indicated that there is significant increase observed in the microbial density of the polluted soil.Total viable count for contami nated soil where 3.40x103 , 2.70x103 and 2.85x103 CFU/g for Naka road, North bank and Gboko Road respectively while for unconta minated soil were 2.90x10 4 , 4.70x104 and 2.70x104 CFU/g respectively. There is significant difference in the total viable count between contami nated and uncontaminated (P<0.05).Altho ugh Igbinosa and Igiehon (2015) observed that the fungal counts of the polluted soil were significantly lower than the bacterial counts generally(P<0.05). This results shows that Cassava waste effluent negatively affect the microbial population. This may be attributed to the negative impact of harsh chemicals like cyanide that is present in the effluent a nd other chemical by-products of cassava fermentation. This finding agrees with (Oti, 2002 and Goodley,2004). Also the Study identified Pseudomonas specie, Bacillus micrococcus, Klebsiella, Escherichiacoli, Staphylococcus and Proteus as bacteria genera found in the study area while AspergillusSpecie were fungi flora identified in this study. These bacteria and fungi species were isolated by previous authors (Knowles, 1988; Ehiagbonare et al., 2009). However, not all these soil microbial where found in the contaminated soil. Pseudomonas, KlebisiellaProteus specie and Trichodema were not found at all in the three area studied but were found in the control soil thereby suggesting that these microbial genera could not withstand the negative impact of the effluent. These findings of concern as disruption of the microbial constitute serious threat to the soil. The fungal counts for the polluted and control soil ranged from fungi count 1.16 x 103 ±5.70 x 101 to 1.4×103±2.82×103 CFU/g, respectively. This suggests that the cassava effluent has effects on the fungal diversity of the polluted soil. The fungal counts were significantly lower than the bacterial counts (p < 0.05); and this is in agreement with the report from Aiyegoro et al. (2007). Conclusion Based on the result of this study the following conclusions are reached. i. That release of Cassava waste effluents to the soil affects the microbial population as well as the microbial diversities of the soil. ii. This waste contains pollutants that also affect the physicochemical composition of the soil. International Journal of Applied Biology, 6(2), 2022 87 Recommendations i. The release of Cassava waste water into the environment should be discouraged. ii. Cassava processor should be trained on simple treatment technique on effluents that will make it less harmful to the environment. iii. There is the need for public awareness on the danger of releasing effluents into the environment. iv. Further research is recommended to find out ways for simple and affordable means of treatment and also ways of converting the effluent into useful substances (waste to wealth) that will benefit mankind. International Journal of Applied Biology, 6(2), 2022 88 References Aiyegoro, O. A., Akinpelu, D. A., Igbinosa, E. O. and Ogunmwonyi , H. I. (2007). Effect of cassava effluent on the microbial population dynamic and physicochemical characteristic on soil community. Sci Focus, 12: 98-101. American Public Health Association (APHA) Standard Methods for the Examination of Water and Wastewater. (2005)American Public Health Association, 20th ed. Washington USA, pp 5-17. Basey, J. M., Mendelow, T. N., Ramos, C. N. (2000). Current trends of community college lab curricula in biology: An analysis of inquiry, technology and content. J Bio. Educ. 34 (2): 80-86 Cheesbrough, M. (2005). District Laboratory Practice in Tropical Countries. Cambridge University Press, United Kingdom, pp. 30-41. Desse, G. and Taye, M. (2001). Microbial loads and Microflora of cassava (ManihotesculentaGrantz) and effects of cassava juice on some food borne pathogens. J. Food Technol. Afri.,6(1): 21-24. Ehiagbonare, J. E., Enabulele., S. A., Babatunde, B. B. and Adjarhore, R. (2009). Effect of cassava effluent on okada denizens. Sci Res Essay, 4: 310- 313. Food and Ag ricultural Organization, FAO. (2006). Impact of cassava processing on environment: FAO Corporate Documents Repository, 12(4): 56-98. Fred, M. and Harold, van Es. (2009). Building Soils for Better Crops, 3rd Edition, Sustainable Agriculture Research and Education Goodley, J. (2004). A Compendium DHI-Water and Environment. 4th Edn., FAO, Canada. International Institute of Tropical Agriculture, IITA. (2011). Cassava processing in Nigeria Research for Development, 15(7): 54-77. Knowles, C. J. (1988). Cyanide utilization and degradation by microorganisms. CIBA Foundation Symposium 140: 3-15. Nwabueze, T.U. and Odunsi, F. O. (2007) Optimization of process conditions from cassava (Manihotesculenta) Lafun production. Afri. J. Biotechnol., 6(5): 603-611. .Ochei, J.O. and Kolhatkar, A.A.(2008) Medical Laboratory Science: Theory and Practice, Tata McGraw-Hill Publishing Company Limited, New York, pp. 637-745. Oti, E. E. (2002). Acute toxicity of cassava mill effluent to the African catfish. Oyewole, O.B. and Afolami, O.A.(2001) Quality and preference of different cassava variety for Lafun production. J. Food Technol. Afri., 6(1): 27-29. Thangavel, R., Nanthis, B., Mary, B. K., Hasintha, W., Manjaiah, K., Cherukumalli, S. R., Sasidharan, S., Jörg, R. Y., Sik, O.U., Choudhur ya, H., Wangjk, C., Tangl X., Wangl, Z., Song m, O. W., Freeman I. I. (2019) Soil organic carbon dyna mics: Impact of land use changes and management practices: A review, Advances in Agronomy, Volume 156, 2019, Pages 1-107