Response of common bean (Phaseolus vulgaris l.) to lime and customized micronutrient fertilizer in Nandi County, Kenya

Low soil fertility associated with nutrient mining of both macro and micronutrients and soil acidity is a major constraint affecting crop production in Western Kenya. The objectives of this study were (i) to determine the effect of customized fertilizer and lime on common bean (Phaseolus vulgaris L.) growth and yield and (ii) to determine the effect of selected micronutrient (boron, zinc and molybdenum) with lime on their uptake and growth of common bean. In the first experiment, a field experiment was conducted on 2 sites of Kapkerer and Kiptaruswo, Nandi County. A 4 × 2 factorial experiment was set up in randomized complete block design. The treatments were Mavuno fertilizer (15:10:18: plus sulphur, calcium, magnesium, iron copper, boron and molybdenum) (0, 185 kg ha-1), Sympal fertilizer (0:23:15 calcium, magnesium, sulphur and zinc) (0, 125 kg ha-1), Diammonium phosphate fertilizer (positive control) (0, 62.5 kg ha-1) and lime (0, and 1.6 or 2.0 t ha-1 depending on specific lime requirement for the site). Yield, phosphorous uptake, below and aboveground biomass were determined. In the second experiment, a greenhouse experiment was conducted at Egerton University using soil from Kapkerer site. A 2 × 2 × 2 × 2 factorial experiment was set up in completely randomized design. The treatments were, boron (0, 3 kg ha-1), zinc (0, 1.5 kg ha-1) Mo (0, 0.6 kg ha-1) and lime (0, 1.6 t ha-1). Plant tissue analysis for micronutrient uptake (boron, zinc and molybdenum) above and below-ground biomass were determined. The results showed that application of lime increased above and belowground biomass, nutrient uptake and yield in common bean while combined application of Mavuno fertilizer with lime further enhanced common bean growth and increased yields by 42%, 30% and 27%, respectively, compared to control, Sympal and DAP. Application of DAP and Sympal in combination with lime did not have a significant effect on common bean yield. On the other hand, the application of boron with molybdenum significantly increased above and below-ground biomass by 24% and 32%, respectively, compared with the control. The application of boron and lime significantly increased aboveground biomass by 11%, while molybdenum with lime application significantly increased belowground biomass by 29%. The results for this study suggest that the use of Mavuno fertilizer formulation can significantly improve common bean productivity in Western Kenya smallholder systems, and inclusion of boron and molybdenum in the fertilizer and liming the soil is necessary for enhanced common bean productivity.