Cover Cropping and Nutrient Management Strategies for Maize Production in Western Africa

Introduction of cover cropping systems may be important to a stable food supply in sub‐Saharan Africa. We examined the effects of three cropping systems in a 2‐yr, four growing season study in Togo: continuous maize (Zea mays L.), maize–mucuna [Mucuna pruriens (L.) D.C.], and maize–pigeon pea (Cajanus cajan L.). Mucuna and pigeon pea were grown in 1‐ or 2‐yr cycles, and three N and two P fertilizer rates were factorially applied on maize. Use of mucuna and pigeon pea after maize in the first year reduced N and P fertilizer needs in the subsequent year. Cover crops increased maize grain yield by 37.5 and 32.1%, respectively, in the second year. Two‐year cumulative economic returns on maize production were optimal when cover crops were grown every other year (every fourth season), compared to continuous maize or annual cover crops. The April 2002 to December 2003 soil N budgets showed a gain of N (>400 kg ha−1) under all cropping systems. Initial soil nitrate (NO3)–N was reduced by 57.8% under the continuous maize system, but increased by 39 and 3.6% under the mucuna‐based and pigeon pea–based systems, respectively. Low (<20 kg ha−1) N losses occurred during the fallow period. Phosphorus losses occurred for all periods, but a mucuna‐based cropping system has potential for soil P replenishment. The relay of a mucuna cover crop into maize in one out of 2 yr was most economical and improved soil N and P status without commercial fertilizers.