Nitrogen effects on maize yield following groundnut in rotation on smallholder farms in sub-humid Zimbabwe

Abstract

Rotating maize (Zea mays L.) with groundnut (Arachis hypogaea L.) has been proposed as a way to maintain soil fertility and prevent maize productivity declines in the smallholder cropping systems of
sub-humid Zimbabwe. Field experiments with fertilizer-N on maize in rotation with groundnut were conducted at three locations with sandy typic Kandiustalf soils. The specific objectives were to (i) evaluate the response to fertilizer-N of maize in rotation with groundnut compared with continuous maize and, (ii) determine the fertilizer-N replacement value of groundnut. Maize grain yields were increased up to 0.7 tha-1 following groundnut compared with continuous maize when no fertilizer was applied to both cropping systems. Maize yield response to fertilizer-N was higher after groundnut than continuous maize. The small groundnut yields were associated with little yield improvement for a subsequent maize crop. Fertilizer needs on maize were reduced by 0 - 64 kgNha-1 when maize followed groundnut.