Higher Cereal and Legume Yields Using Ca-bentonite on Sandy Soils in the Dry Eastern Uganda: Increased Productivity versus Profitability

Moisture stress grossly limits crop yields in sub-Saharan Africa. Ca-bentonite holds and avails water for plant uptake. However, despite its availability and increasing droughts in Uganda, its use is limited, partly due to inadequate empirical evidence about its benefits. This 3-season on-farm study assessed the benefits accruing from Ca-bentonite use. Crops included: maize (Longe 10H), finger millet (Seremi-2), sorghum (SESO-3), green-grams (Mauritius) and groundnuts (Serenut 6). Treatments were: Ca-bentonite (2.5 t ha -1 ), Ca-bentonite combined with manure (FYM) and/or phosphate (DAP/SSP), replicated five times in CR design. Ca-bentonite (2.5 t ha -1 ) increased the grain yields of maize, millet, sorghum, green-grams and groundnuts by 11, 20, 14, 17 and 5% above the control. Bentonite combined with DAP/SSP and/or FYM increased maize, finger millet, sorghum, green-grams and groundnuts yields by 14-82%, 22-42%, 23-42%, 32-42% and 4-26%, respectively. Higher grain yields were partly attributed to increased soil moisture following bentonite application. Compared to other crops, bentonite was more profitable when used on the higher priced groundnuts. Considering the high bentonite cost, application on high value crops, blending with other materials and policy support are recommended, to make this locally available resource economically viable for smallholder farmers, thereby help them cope better with increasing droughts.