Effect of Mucuna Green Manure Rate Applied on Maize Grain Yield During the Application Season

Abstract

Maize yield in Kenya is constrained by inadequate supply of nitrogen and there is need to search for locally available and potentially low-cost N sources. Consequently, on-farm research was carried out in southwest Kenya in the period 2002-2005. The objective was to evaluate effect of Mucuna pruriens green manure biomass application rate on maize grain yield in sandy clay soil. Treatments evaluated were: mucuna green manure applied at rates of 0, 30, 60, 120, 240 and 480 kg N ha-1; and inorganic fertilizer-urea at 0, 30, 60 and 120 kg N ha-1. The experimental design was randomized complete block with four replications. Results obtained showed that mucuna application rate of 30 kg N ha-1 did not significantly improve maize grain yield. Its application at 60 kg N ha-1 significantly increased maize grain yield only in seasons when rainfall was high notably in long rains. But, mucuna green manure applied at a rate of 120 kg N ha-1 significantly improved maize grain yield in both short and long rain seasons when rainfall amounts received were variable. Application of mucuna green manure at higher rates of 240 and 480 kg N ha-1 made no further significant increase in maize grain yield. Therefore, application rates lower than 120 kg N ha-1 equivalent of mucuna green manure biomass may be inadequate and would require supplementation with inorganic fertilizer N if maize grain yield is to be increased. Key words: Maize, grain yield, green manure, mucuna, biomass, fertilizer