Theses and Dissertations

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Theses and Dissertations (Soil Science)

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    Open Access
    Land Evaluation under Different Environmental and Geological Conditions in Southern Nigeria.
    (Obafemi Awolowo University, 1985) Aiboni, Victoria; Ashaye, T. I.
    Soils of Ibadan and Remo were evaluated for the cultivation of yam and cassava. The soils in farmers' plots in both sites were characterized by their morphological, physical, chemical and mineralogical properties. The slope, climatic and other land surface features limiting the cultivation of yam and cassava were also identified. Actual and potential land productivity indices were developed based on the soil, slope and climatic characteristics limiting the cultivation of yam and cassava at both sites. Ibadan site is underlain by Precambrian basement complex rocks whilst Remo site overlies cretaceous sedimentary rocks. Twelve soil series were identified in Ibadan site and nine in Remo site. Forty-five plots under yam and cassava were selected in Ibadan site and sixty-nine in Remo site to cover the various soil series. The farm, management level was assessed with questionnaire and direct observation of individual farm land. Parameters considered in the land productivity index are soil depth, drainage, soil texture, surface stoniness, slope, annual rainfall, primary nutrients, organic matter, base saturation, mineral reserve and nature of clay mineral. Productivity index was developed with appropriate ranges in percentage to reflect individual factor. Soil fertility and potential productivity indices were also developed. Land productivity index range from 3.77 to 60.91 and 19.82 to 48.27 for Ibadan and Remo, respectively. Cassava yield ranged from 6.30 to 11.50t/ha and 5.23 to 7.26t/ha for Ibadan and Remo, respectively. Yam yield ranged from 3.75 to 6.00t/ha and 6.20 to 8.00t/ha in Ibadan and Remo, respectively. The wide range of indices recorded for Ibadan soils is a reflection of the complexity of the parent material. Correlation coefficients between calculated and measured yield are r = 0.81 and 0.77 for yam and cassava in Ibadan site and r = -0.95 and -0.22 for yam and cassava in Remo site. The poor correlation of yields in Remo site may be due to the greater response of these soils to management. Chi-squared analysis indicates the independence between measured and calculated yield in both sites.
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    Open Access
    Soil Test and Nitrogen, Phosphorus and Potassium Requirement of Maize in Southwestern Nigeria.
    (Obafemi Awolowo University, 1985) Adebusuyi, Benson Adekunle; Aduayi, E.A.; Sobulo, R.A.
    Soil testing as a fertilizer advisory service to farmers is not common in Nigeria. Method of sample treatment and time of sampling in relation to fertilizer treatment need to be properly established. In order to shorten the time required for analysis, a multi-element extractant has to be developed to cover more than one element at a shaking time. This study was undertaken to evaluate suitable and rapid methods for a soil testing programme. Simultaneous extraction of P and K at a shaking time of 5 minutes was carried out. Bray II was recommended for the simultaneous extraction of P and K. The field trial was conducted at five locations viz: Ikenne, Akure, Agbede, Ilorin and Ilora. Available nitrogen, NO3-N was the best index of N availability in soil for short period of four weeks but the poorest under continuous cropping. Soil N critical levels were established with deficient values of 20 ppm NO3-N, 0.05% total N and 0.7% carbon while the critical values were 30 ppm NO3-N, 0.11% total. N and 1.26% carbon. Field correlation and calibration studies was used to establish soil critical P and K. Maize responded to N fertilizer at Ilorin, a savanna zone up to 150 Kg N/ha but lower response to N was observed in forest zone. The critical soil P levels at about 90% relative yield in the field and glasshouse were 9.5 and 12 ppm P while the corresponding deficient levels at 50% relative yield were 6 and 7.5 ppm P respectively. The critical soil K by Bray I, Bray II and NH4 0AC in the field study was higher than greenhouse value with a range of 0.33 - 0.38 me K/100g. The critical N, P and K concentration in maize leaf. The tissue at four and eight weeks stage were compared. The relationship between the tissue content at four weeks and relative yield was better than at eight weeks while the critical values were 3.2%, 0.4% and 3.9% N, P and K at four weeks respectively and 2.80%, 0.29% and 2.50% N, P and K for eight weeks respectively.
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    Open Access
    Nitrogen Nutrition of White Yam (Dioscorea rotundata Poir) Grown in Two Selected Locations of Southwestern Nigeria.
    (Obafemi Awolowo University, 1987) Okpon, Stephen Nelson; Aduayi, E. A.
    Soil physical and chemical evaluation was carried out in five selected locations of southern Nigeria viz: Ile-Ife in Oyo State, Ado Ekiti in undo State, Asaba in Bendel State, Abakaliki in Anambra State and Ogoja in Cross River State that are known to support the production of white yam (Dioscorea rotundata Poir). Of these five locations, Ile-Ife and Ogoja were selected for field experiments. Four rates of nitrogen (0, 40, 80 and 120 kg N/ha) as ammonium sulphate [(NH4)2SO4)] were applied to yams grown on ridges for three seasons. Soil physical and chemical investigations revealed that the inherent fertility of the soils which the farmers rely on for yams yield cannot provide sustained productivity. Ammonium sulphate fertilizer at 120 kg N/ha proved adequate for sustaining increased tuber yield of yams at Ile-Ife and Ogoja locations. The fact that the yams were collected in Ile-Ife and planted in Ile-Ife (forest zone) and Ogoja (Savanna zone) did not have any adverse effect on tuber yield and tuber quality in terms of crude protein, starch and glucose contents. These nutrient classes increased proportionately as the N- level increased. High accumulation of mineral nutrients in both the yam flour and the peels were observed for yams grown at Ile-Ife and Ogoja locations. Chemical analysis of the yam flour indicates that with judicious use of N- fertilizer, the nutritional value of the yam flour and peels could be substantially increased in the white yam. It was observed that increasing level of (NH412SO4 resulted in reduction in soil p11 from 6.7 to 5.3 and P from 11.6 to 4.5 ppm in Ogoja whereas it was less felt in Ife. Soil pH was reduced from 6.4 to 6.1 and P from 12.6 to 6.5 ppm in Ife. Statistical analysis showed N- from ammonium sulphate fertilizer highly correlated with yield, protein, starch and glucose.
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    Open Access
    Effect of Cowpea Mosaic Virus on Nodulation and Nitrogen Fixation in Cultivars of Cowpea Vigna Unguiculata (L.) Walp
    (2015-05-19) Samuel, Chinedum Johnson
    This study was carried out to assess the effects of Cowpea Mosaic Virus (CMV) infection on agronomic parameters, nodulation and N2 fixation in four cultivars of cowpea namely IFOB, Ife Brown, Obwell Standard and BPQ/C with and without Starter N application in the greenhouse. This was with the aim of screening for which Cowpea variety is naturally resistant to the Cowpea Mosaic Virus. The first experiment was set up using a Randomized Complete Block Design (RCBD) on treatments consisting of four cultivars of cowpea in two sets: (a) disease free and (b) infected with CMV, each replicated four times. The second experiment involved the assessment of the effect of Starter nitrogen (N) on nodulation and nitrogen fixation in cultivars of cowpea inoculated with CMV. The layout was also set up using RCBD and the treatment consisted of four cultivars of cowpea also in two sets: (a) inoculated with CMV plus Starter N and (b) the second set uninoculated without Starter N each replicated three times. Analysis of variance (ANOVA) was used to analyze the treatment effects. Means of the treatment effects were also compared using Duncans New Multiple Range Test (DNMRT) at 0.05 level of significance. Results of the study showed that plant height, days to 50% flowering, shoot, root and nodule dry weight, number of nodules, total nitrogen content and total nitrogen fixed by inoculated Ife Brown, Obwell Standard and BPQ/C were significantly reduced (P<0.05) with or without Starter N when compared with their corresponding uninoculated cultivars, except for IFOB which showed a high level of resistance to inoculation with CMV, with or without Starter N. This study also showed that there was no improvement in the performance of the infected cowpea cultivars in presence of Starter N. It was concluded that while Obwell Standard, BPQ/C and Ife Brown were susceptible to CMV with or without Starter nitrogen, IFOB was resistant.