To assess the quality of commercial organic fertilizers in Uganda market, a quick survey was conducted to establish the organic fertilizers being sold in Container village market in Kampala Capital City. Different products were found being sold as organic fertilizers. Four of these fertilizers are two solid (Biochar and Fertiplus) and two liquid (Biogrow and Digrow) selected for a field study. Field trials to assess the performance of the fertilizers and local farmyard manure on bush beans (Phaseolus vulgaris) were conducted at two locations (Kabanyolo and Nkozi) for two successive seasons in 2017 and 2018 using a randomized complete block design in four replications. Forty days after planting, fresh and dry weights were estimated while biomass and grain yield were determined at harvest. The results showed inconsistencies. For example, although Biochar was found to significantly (P=0.043) increase the mean fresh weight of bush beans in season 1 (2017) at both sites (Kabanyoro and Nkozi), this was not the case in season 2 (2018). Similar performance was found with the other treatments. The mean biomass did not increase significantly (P>0.05) in season 1 (2017) and season 2 (2018) at both locations. The results in season 2 (2018) showed no significant (P>0.05) increase in the mean yield. These results were attributed to the extreme weather conditions experienced in both seasons (severe drought during season 1 and heavy rains that led to prolonged vegetative growth during season 2). These field trials should be repeated under controlled environment to minimize the weather effect.

Ferralsols form a dominant type of soil on which most crops are grown in the Lake Victoria agro-ecological zone. Soil acidity has been recognized among the most important agricultural problems in such soils, which adversely affect crop production and productivity. A study was conducted with the objective of determining the effect of applying low rates of lime and chicken manure on selected soil chemical properties. Using a Split Plot Factorial Randomized Complete Block Design, agricultural lime (0.0, 0.5, 1.0, 1.5 & 2.0 t•ha −1 ) as the main plot and chicken manure (0.0, 1.0, 2.0 & 3.0 t•ha −1 ) as sub-plot were applied, replicated three times. The test crop was common bean var. NABE 15. The experiment was conducted for three rainy seasons, two seasons on-station and one season on-farm on Ferralsol soil in the Lake Victoria crescent of central Uganda. The results showed that applying low rates of lime with chicken manure significantly (p < 0.05) increased pH, CEC, P, N, K, BS and Mn changes at Mukono but not Masaka. A strong positive significant (r 2 = 0.987) relationship with pH change was obtained when 0.5 t•ha −1 lime was applied with the four chicken manure rates in Mukono. From the study, we recommend the application of small quantities of lime at 1.0 t•ha −1 with either 2.0 or 3.0 t•ha −1 chicken manure.

An experiment was conducted to determine the effect of applying low rates of lime and chicken manure on bean (var. NABE 15) growth and yield on Ferralsols. Using split plot factorial randomized complete block design, lime (0.0, 0.5, 1.0, 1.5 and 2.0 t ha -1 ) as the main plot and chicken manure (0.0, 1.0, 2.0 and 3.0 t ha -1 ) as sub plot, were replicated three times. The experiment was conducted for three rainy seasons, two seasons' on-station and one season on-farm using promising combinations from the onstation experiments. In Mukono, increased grain yield of 117% over the control was observed at 2.0 t ha -1 lime with 1.0 t ha -1 manure. Applying 1.5 t ha -1 lime with 2.0 or 3.0 t ha -1 manure resulted in a yield increase of 81.1 and 103.6% over the control respectively. Applying 0.5 t ha -1 lime or 1.0 and 2.0 t ha -1 manure alone caused minimal yields. In Masaka 0.5 t ha -1 lime with 3.0 t ha -1 manure, resulted in 95% yield increase over the control. The control and 0.5 t ha -1 lime yielded the least. All the BCRs were less than one; there was net gain in nutrients (NPK) for the subsequent crop.