Effect of Pre-Crop Type on Growth and Yield of Maize on Two Soils in the Guinea Savanna Zone of Ghana

Mucuna (black type) (Mucuna pruriens var. utilis), devil-bean (Crotalaria retusa), cowpea (Vigna unguiculata), maize (Zea mays L.) and sorghum (Sorghum bicolor Moench.) were grown as preceding crops to maize in a Ferric Luvisol and a Haplic Luvisol in the Guinea savanna zone of Ghana in June 2001. Their effects on growth, grain yield and arbuscular mycorrhiza formation of the following maize in a rotational system were assessed. A non-fertilized weedy fallow treatment was also included as control. Each of the legume pre-crops received 40 kg P ha-1 and 30 kg K ha-1 whereas the cereals received 60-40-30 kg N-P-K ha-1. The legume biomasses were incorporated into the soil in June 2002, two weeks before maize was planted and grown to maturity. Each of the legumes produced over 5 t ha-1 of biomass within the cropping season. Devil-bean tended to be the most efficient in increasing maize grain yield (4.04 t ha-1 in the Ferric Luvisol and 1.2 t ha-1 in the Haplic Luvisol). This is probably due to its relatively higher mean shoot N accumulation across the two locations (214 kg N ha-1) and its greater stimulation of mycorrhizal fungal colonization (25.5%) in the following maize, especially in the Haplic Luvisol. Devil-bean and mucuna generally enhanced maize stover growth. Devil-bean can, therefore, produce significant benefits when used as a preceding crop to maize in a rotational system