Economic analysis of maize–bean production using a soil fertility replenishment product (PREP-PAC) in Western Kenya

Abstract

The Phosphate Rock Evaluation Project (PREP) is testing PREP-PAC, a soil fertility replenishment product specifically designed to ameliorate nutrient-depleted "patches" symptomatic of the worst maize-bean intercrops of smallholders’ fields in western Kenya. PREP-PAC contains two kg Minjingu rock phosphate, 0.2 kg urea, legume seed, rhizobial seed inoculant, seed adhesive and lime pellet, is assembled and is sold for Ksh. 42 (US $ 0.76) and is intended for 25 m2 areas. PREP-PAC was tested on 52 farms in four districts of western Kenya during 1998 and compared with adjacent control plots. Farmers selected either a local bush or climbing variety (cv. Flora) of Phaseolus vulgaris as an intercrop with maize (Zea mays). Use of the combined PREP-PAC and climbing bean package increased maize and bean yields by 0.72 and 0.25 t ha-1, respectively (P < 0.001), resulting in a 161% return on investment. Total revenue from low pH soils (<5.2) was Ksh. 25 for the control and Ksh. 47 for PREP-PAC. In moderate soil pH >(5.3), total revenue was Ksh. 31 for control and Ksh. 68 for PREP-PAC (P < 0.05). Opportunity exists to distribute an affordable soil fertility restoration package among smallhold farmers but the profitability from its use is dependent upon soil conditions and accompanying legume intercrops.