Browsing by Author "Osunbitan JA"

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    Application of the AquaCrop model in decision support for optimization of nitrogen fertilizer and water productivity of soybeans
    (2021) Adeboye OB; Schultz B; Adeboye AP; Adekalu KO; Osunbitan JA
    Modelling of the effects of water and different levels of nitrogen on evapotranspiration and water productivity of rainfed soybeans is very important in optimising resource use in the production of the crop. The objective of the study was to model evapotranspiration, soil water storage and water productivity of rainfed soybeans under different levels of nitrogen fertilizer by using the FAO AquaCrop model. Field experiments were conducted at the Teaching and Research Farms of Obafemi Awolowo University, Nigeria in the rainy seasons of 2015 and 2016. There were five levels of nitrogen, which are 00, 25, 50, 75 and 100% of the recommended nitrogen applications and two varieties of soybeans, which produced a 2 by 5 factorial experimental design. The data of the wetter year 2015, were used for calibration of the AquaCrop model because AquaCrop is water driven. The 2016 data were used for the validation. The AquaCrop model simulated canopy cover with R2 and EF > 0.90, d-index ≥ 0.99. The model captured the trend of the soil water storage well, R2 and EF ≥ 0.70. The AquaCrop model simulated soil water storage below wilting point for seasonal rainfall less than 600 mm, and it did not overestimate it. The model predicted evapotranspiration with R2 and EF ≥ 0.89, d-index = 1.00. Above ground biomass was overestimated even though R2 ≥ 0.98. Although, nitrogen stress reduced seed yield and water productivity, there was no under or over estimation of the seed yields. They were predicted with low error under the different levels of nitrogen fertilizer, R2 ≥ 0.99, EF and d-index ≥ 0.99. The AquaCrop model is suitable for simulating canopy cover, soil water storage, evapotranspiration, and seed yield of rainfed soybeans with different levels of nitrogen fertilizer under temporal distribution of seasonal rainfall. Therefore, it can serve as a useful tool for smallholder farmers in predicting productivity of soybeans and optimising resource allocation, land and water use in the tropical farming systems. We recommend simulation of the effects of pest on biomass, seed yield and water productivity by subsequent versions of the AquaCrop model. In addition, incorporating an economic sub-unit in the model will enable users to make financial decisions.
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    Effect of compost extract processing parameters on the growth and yield parameters of Amaranthus and Celosia Vegetables
    (2021) Oyewusi TF; Osunbitan JA
    In an effort to provide a more affordable fertilizer alternative to farmers, the effect of compost extract processing parameters was investigated on the growth and yield parameters of vegetables. In order to extract nutrients from compost, composted chicken manure was steeped in a container of a predetermined water and subjected to three processing parameters (compost to water ratio, steeping time and water temperature) at different levels. The compost extract produced was used for production of Amaranthus and Celosia vegetables through fertigation by pot experiment in a screenhouse. The growth and yield parameters of the vegetables were determined using standard procedures. The results showed that highest values of growth and yield parameters were obtained in vegetables with fertigation of compost extract compared to the control. The three processing parameters of the applied compost extract significantly (p < 0.05) affected growth and yield parameters of both vegetables. The maximum growth and yield parameters for both vegetables occurred with fertigation of extract made under compost to water ratio of 1:3 when steeped for 72 h at 25 °C water temperature. Therefore, compost extract is well suitable for vegetables production.
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    Investigation into physico-chemical properties of compost extract as affected by processing parameters
    (2021) Oyewusi TF; Osunbitan JA; Ogunwande GA; Omotosho OA
    In a view to convert the abundant chicken manure generated which constitute environmental hazard into a more useful form, investigation was carried out on efficient extraction of nutrients from composted chicken manure into compost extract which will serve as an alternative to inorganic fertilizer. Chicken manure was co-composted with sawdust using a passively aerated composting method. The resultant compost was subjected to 3×3×3 processing parameters: compost rate (10, 15 and 20 t/ha), steeping time (24, 48 and 72 h) and water temperature (25, 35 and 45 °C). The resulting extract was analyzed for its physico-chemical properties (pH, EC, TC, TN, TP, TK, Ca, Mg and Na) using standard procedures. The results showed that compost extract gave higher amount of nutrients when compared to particulate compost and was significantly (p < 0.05) affected by compost rate, steeping time and water temperature. In conclusion, suitable conditions for physico-chemical properties of the compost extract were obtained at 20 t/ha compost rate at 72 h steeping time and 25 °C water temperature.
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    Investigation into the suitability of well water near cassava processing areas for drinking and irrigation purposes
    (2021) Oyewusi TF; Osunbitan JA; Taiwo A
    Water used for domestic and irrigation purposes are sometime contaminated by organic and inorganic pollutants from cassava processing centres. Accordingly, groundwater from ten randomly wells were analyzed for pH, turbidity, total suspended solids (TSS), total dissolved solids (TDS), electrical conductivity (EC), sodium adsorption ratio (SAR), CN−, Na+, K+, Ca++, Mg++ and NO3− ion concentrations and the microbial content to determine the suitability of these waters for drinking and/or irrigation purposes. The qualitative analysis reveals that all the ten sites recorded permissible of limits for TDS (<500 mg/l for drinking purposes). Also, all the sites had permissible limits for EC values (<750 dSm−1 recommended for irrigation water) and thus can be used for irrigation with adequate attention on irrigation duration and frequency, drainage and crop species. However, none of the groundwater samples satisfy the World Health Organization (WHO) guidelines of 0.1 mg/l cyanide value and zero coliform bacterial count for drinking water quality and are therefore not recommended for drinking.