Effects of Conservation Tillage, Fertilizer Inputs and Cropping Systems on Soil Properties and Crop Yield in Western Kenya

Abstract

An on-farm experiment was conducted in Western Kenya (Busia district) in the long rain season of 2005 to investigate the effects of conservation tillage on soil properties and the crop yields. The experiment based on a split–split plot design with three replicates and six core treatments arranged in a factorial combination of nitrogen application and cropping systems was adopted. Maize variety IR (striga resistant) was planted as a test crop, soybean (SB20) variety as an intercrop and for maize–legume rotation. Soil pH, moisture content and organic carbon were analysed in soil whereas total P and N were analysed in the plant tissue. Conservation and conventional tillage systems combined with cropping systems (intercropping, rotation and continuous) at 0 and 60 kg N/ha application were tested. Residue incorporation was done to all plots. The soil was sampled before and after harvesting to compare the effects of the treatments. Weeding for conservation tillage plots was by hand pulling. Combinations of conservation tillage, continuous and with application of 60 kg N/ha, for maize gave the highest yield of 2.8 t/ha. The combination of conservation tillage, rotation and application of 60 kg N/ha gave 2.5 t/ha maize grain. Combination of conservation tillage rotational cropping system at 60 kg N/ha application gave the highest soybean yield (1.23 t/ha). Soil carbon showed that there was significant difference between the conservation tillage and conventional tillage as well as the increase of the soil carbon from initial level of 1.44% to the highest percentage soil carbon of 1.9%.