Browsing by Author "Ebanyat Peter"

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Maize Response to Fertilizer and Nitrogen Use Efficiency in Uganda
(American Society of Agronomy, 2012) Kaizzi C. Kayuki; Byalebeka John; Semalulu Onesmus; Alou Isaac; Zimwanguyizza Williams; Nansamba Angella; Musinguzi Patrick; Ebanyat Peter; Hyuha Theodore; Wortmann S. Charles
Maize (Zea mays L.) is an important smallholder crop in Uganda. Yields are low because of low soil fertility and little fertilizer use. Yield response to nutrient application and economically optimal rates (EOxR, where x = N, P, or K) and N use effi ciency (NUE) were evaluated. Twenty-two trials were conducted in four agroecological zones. Yield was consistently increased with N application. Mean maize yield with no N applied (N0) was 1.79 Mg ha–1 and increased by 120% with N application. Mean EONRs were 45 to 24 kg ha–1 N with fertilizer use cost to grain price ratios (CPs) of 10 to 30. With N applied, the mean increase in yield due to P application was 0.28 Mg ha–1 and mean EOPRs were 9 to 1 kg ha–1 P with CPs of 10 to 50. Yield was not increased with K application. Profi tability was greater for N than P application. Mean aboveground biomass N with 0 and 150 kg ha–1 N applied was 46.3 and 94.3 kg ha–1, respectively. Mean N concentration and N harvest index at the EONR were 1.60 and 63.8%, respectively, and higher than for N0. Mean recovery effi ciency, partial factor productivity, and agronomic effi ciency declined with increasing N rate and were 66%, 86 kg kg–1, and 41 kg kg–1, respectively, at the EONR. Fertilizer N use can be very profi table, with high NUE, for smallholder maize production in Uganda, and the fi nancial capacity of smallholders to use fertilizer will increase with reduced CP
Optimizing Smallholder Returns to Fertilizer Use: Bean, Soybean and Groundnut
(2011) Byalebeka John; Kaizzi C. Kayuki; Semalulu Onesmus; Alou Isaac Newton; Zimwanguyizza Williams; Nansamba Angella; Odama Emmanuel; Musinguzi Patrick; Ebanyat Peter; Hyuha Theodore; Kasharu Appollo K.; Wortmann Charles S.
Smallholder African farmers commonly lack the financial means to purchase enough fertilizer for application at the economical optimal rates (EOR), or the rates for maximization of net returns ha−1, to all of their land. Research was conducted for bean (Phaseolus vulgarisL.), soybean (Glycine maxL.) and groundnut (Arachis hypogaeaL.) to establish a basis for determining the combinations of crops, nutrients, and application rates to optimize net returns to fertilizer use and the benefit:cost ratio (BC) in Uganda. Yield response to nutrient application, EORs, and equations for estimating BC were determined. Eleven to 17 trials were conducted for each crop. Mean yields were increased by 92%, 111%, and 92% for N applied to bean, and P applied to soybean and groundnut, respectively, at 15kgha−1, with less yield responses for P applied to bean and K applied to soybean and groundnut. Mean yield peaked at 1.81, 1.92, and 1.71Mgha−1for bean, soybean, and groundnut, respectively. Mean EOR varied with fertilizer cost relative to grain price (CP) and were 27–42kgha−1N for bean, and 13–29kgha−1P with higher rates for groundnut compared with bean. The greatest BC was for N applied to bean followed, in decreasing order, by P applied to soybean or groundnut, P applied to bean, and K applied to groundnut or soybean. Consideration of the six sets of crop–nutrient response functions developed enables optimization of smallholder investment in fertilizer by identifying the crop, nutrient, and application rate combinations that maximize net returns on investments in fertilizer use. This approach is applicable for smallholder crop production globally where farmers cannot purchase enough fertilizer to apply at EOR.We studied fertilizer response for bean, soybean, and groundnut in Uganda. Smallholders often have little money for fertilizer. They need to optimize returns on their small investment. Returns were highest for N applied to bean and P applied to soybean and groundnut. Information is given for selecting crop/nutrient/rate combinations for high net returns. This gave 100% more net return compared with maximizing net returns per hectare. The methodology is adaptable to smallholder farming situations globally.
Sorghum Response to Fertilizer and Nitrogen Use Efficiency in Uganda
(American Society of Agronomy, 2012) Kaizzi C. Kayuki; Byalebeka John; Semaluluo Onesmus; Alou Isaac; Zimwanguyizza Williams; Nansamba Angella; Musinguzi Patrick; Ebanyat Peter; Hyuha Theodore; Wortmann S. Charles
Sorghum [Sorghum bicolor (L.) Moench] is important for smallholder production in semiarid parts of Uganda. Grain yields are low because of low soil fertility. Little fertilizer is used. Yield response to N, P, and K application, economically optimal rates for N, P, and K (EONR, EOPR, and EOKR, respectively), and N use effi ciency (NUE) were evaluated at 11 site-seasons. Mean sorghum yield with no N applied (N0) was 0.69 Mg ha–1 and was consistently increased by a mean of 230% with N application. Mean EONRs were 34 to 18 kg ha–1 N with fertilizer use cost to grain price ratios (CPs) of 10 to 30, respectively. Mean EOPRs were 11 to 2 kg ha–1 P with CPs of 10 to 50, respectively. Sorghum did not respond to K application. Net economic returns were greater for N than P application. Mean aboveground biomass N with 0 and 90 kg ha–1 N applied was 31.3 and 75.9 kg ha–1, respectively. Grain N concentration, N harvest index, and internal NUE at the EONR were 1.67%, 53.2%, and 31.8 kg kg–1, respectively, and higher than for N0. Mean recovery effi ciency, partial factor productivity, and agronomic effi ciency declined with increased N rate and were 135%, 79 kg kg–1, and 52 kg kg–1, respectively, at the EONR. Th e profi t potential of fertilizer N use is high for smallholder sorghum production in Uganda. Policy interventions to reduce fertilizer cost and improve grain marketing effi ciency will enable smallholders to increase fertilizer use for substantial increases in sorghum production.