Macro and micronutrient fertilization and soil amendments for combating poor soil responsiveness in Maize-Desmodium intercrop in western Kenya

Poor soil responsiveness (PRS) is a major constraint to sustained crop production in subSaharan Africa (SSA). Combating PRS can be achieved through a combined application of organic and inorganic resources aimed at supplying both macro and micro nutrients. In addition, micronutrient supplementation in such fertilization regimes can help in enhancing agronomic efficiencies of added nutrients. A field experiment was carried out in Sabatia and Hamisi sub-counties in Vihiga county, western Kenya, to determine the effects of different application rates of macronutrients nitrogen (N), phosphorus (P), potassium (K) and micronutrient (Zn) on maize (Zea mays) and desmodium (D. intortum) production in poor responsive soils. Both the macro and the micronutrients were sourced from Farm Yard Manure and NPK fertilizer and commercially available Zinc sulphate heptahydrate. This was undertaken during the long rains (LR) and short rains (SR) seasons’ of 2015. Treatments comprised of NPK fertilizer combined with FYM, each at different rates so as to supply an optimal rate of 100 kg N ha-1 and 30 kg P ha-1, 60 kg K ha-1 and 3 kg Zn ha-1. Three replications for each treatment in a Randomly Complete Block Design (RCBD) were implemented. Soils were sampled and analyzed for pH, N, P, K, Ca, Mg, Na and carbon at critical growth stages. Results showed that soils treated with a combination of NPK fertilizer, FYM, lime and Zn demonstrated better maize yield responses which were significant at (p<0.05) but the responses varied across sites. For the LR2015 season, the treatment with NPK, Lime, FYM and Zn yielded 7.5, 5.8, 6.6 and 7.3 t ha-1 in site 1 and 2 (Sabatia) and sites 3 and 4 in Hamisi sub-county, respectively. Desmodium did not show any clear responses across sites indicating a need to carry out further research on appropriate fertilization rates in a Maize-Desmodium intercrop. This technology can be adopted by farmers in Vihiga County, majority of whom practice intensified crop-livestock farming. By overcoming poor yields of food crops while addressing their nutritional value, poor soil responsiveness at farm level will be alleviated. In addition, the inclusion of micronutrient Zn in fertilization programmes can help in overcoming micronutrient deficiency prevalent in soils of Vihiga County.