Rotational Effects Of Legumes On Maize Yield

Application of inadequate quantities of fertilizers limits maize yield in Ghana. Experiments were conducted to determine the effect of Mucuna pruriens, Canavalia ensiformis, and soybean (Glycine max (L.) Merrill) on maize (Zea mays L.) grain yield under 4 mineral fertilizer N levels in a rotational system. The legumes were established in April of 1996 and 1997 at Ejura in the forest-savanna transition zone of Ghana. During August of the respective years, the vegetation on the plots was slashed with a cutlass. Maize was planted in all the plots with blanket P and K application. Fertilizer N was applied as urea at four rates (0, 30, 60 and 90 kg N/ha) to the maize in split applications at 1 and 5 weeks after planting. Mucuna and Canavalia produced more than 3 t/ha of biomass within 4 months. Mean maize grain yields after the legumes without fertilizer N were 2.3, 1.6 and 1.0 t/ha for Mucuna, Canavalia and soybean, respectively. Maize grown after legumes responded to fertilizer N and this is an indication that the legumes didn’t supply the entire N required by maize for optimum yield. The highest marginal rates of return of maize grown after canavalia and soybean were at 90 kg N/ha whilst that of mucuna was at 60 kg N/ha. It was concluded that planting Mucuna and maize in rotation is the best among the systems considered in terms of monetary gain and soil organic matter addition and the application of 60 kg N/ha to maize planted after Mucuna was the most efficient management option.