Effect of conservation agriculture management practices on maize productivity and selected soil quality indices under South Africa dryland conditions

Abstract

Conservation agriculture experiment was conducted under irrigated and dryland conditions during 2007/2008-summer cropping season to determine a suitable soil-crop management practice for increase maize yield. The study consisted of tillage practices (conventional, minimum and zero), cropping systems (sole and intercrop plots) and fertilizer regimes (unfertilized control, low, adjusted low and optimum) as treatments. Minimum and zero tillage practices constituted the conservation agriculture tillage practices while supplementation of low fertilizer rate with seed inoculation using growth enhancing microbial inoculant constituted the adjusted low fertilizer rate. Fertilizer application gave a significant (P < 0.05) maize grain yield increase at both trial sites. Maize grain yield ranged from 1254 to 3683 kg ha-1 and from 1738 to 3199 kg ha-1 under supplementary irrigation and dryland non-irrigated condition, respectively. The highest maize grain yield obtained at optimum fertilizer rate did not differ significantly from that of adjusted low rate under dryland and inherent low soil nutrients condition. Although the adjusted low fertilizer rate gave no maize grain yield advantage over the low rate in soil with fairly high native nutrients, it however resulted in better crop responses and conservation of some of the soil properties studied under low-nutrients soil status. Zero tillage as a conservation agriculture practice gave the highest maize grain yield of 2805 and 2776 kg ha-1under supplementary irrigation and dryland conditions, respectively. It also resulted in better conservation of soil nutrients resource than the conventional tillage practice. Key words: Conservation agriculture, fertilizer regimes, cropping systems, maize yield, seed inoculation.