Effects Of Commercial Chemical Products On Maize Yield In Different Agro-Ecological Zones In Kenya

ABSTRACT

Crop production in Central and Western Kenya is mainly restricted by nitrogen (N) and phosphorus (P) deficiency and limited investment capacity in N and P inputs by smallholder farmers. Nutrient inputs to the soil are often utilised inefficiently due to environmental factors, soil related factors (e.g., P fixation by sesquioxides) and management factors. Integrated soil fertility management (ISFM) practices aim at maximizing the use efficiency of applied nutrients. This study sought to test the efficacy of manufactured chemical products that may be used as fertilizers in different agro-ecological zones in Kenya. Such products included seed P coatings, foliar application with P and micronutrients and urease/nitrase inhibitors that slow N release. Experiments with alternative P formulations were carried under greenhouse conditions (Accele-grow, Agroleaf HP, Aton AZ, Broadacre, Myconate, Teprosyn Zn/P, Turbo-seed Zn and Turbo-top) using a randomized complete block design (RCBD) and also in multi-locational field trials with farmer groups in Bondo and Meru South districts in Kenya in two consecutive seasons. The products (Agroleaf HP, Teprosyn Zn/P and Turbo-top) were applied in combination with triple super phosphate (TSP) fertilizer at 13 kg P ha-1, as the P supplied through the products was assumed insufficient to attain adequate crop yields. Response to P was assessed by including treatments with P addition at 0, 13 and 26 kg P ha-1. The N inhibitor products (Agrotain and Super U) were evaluated only under field conditions in a multi-locational trial where a farmer group equalled to one replicate in Meru South district during two consecutive seasons. Response to N was evaluated by including treatments with N in form of urea at 0 and 46 kg N ha-1. In the greenhouse trial, none of the products significantly (P