Effects of tillage and cropping systems on yield and nitrogen fixation of cowpea intercropped with maize in northern Guinea savanna zone of Ghana

Abstract

Published information is scanty on the response of crops in mixed cropping systems to the various tillage systems practised by farmers in the northern savanna zone of Ghana. A field experiment assessed the yield and nitrogen (N) fixation of cowpea (Vigna unguiculata (L.) Walp) intercropped with maize (Zea mays L.) on four different tillage systems at Nyankpala in the Northern Region of Ghana. The experiment was laid in a split-plot design with four replications. The main factor was tillage systems comprising conventional (Con), bullock plough (BP), hand hoe (HH) and zero tillage (ZT). The sub-factor was cropping systems (CRPSYT) which consisted of sole maize, sole cowpea, maize/cowpea inter-row cropping system, and bare fallow in 2000. The last-named was replaced by maize/cowpea intra-row cropping system in 2001. The results showed that Con and BP, which produced over 10 cm plough depth, significantly reduced soil bulk density that favoured significant (P