Conservation Agriculture: Maize-legume Intensification for Yield, Profitability and Soil Fertility Improvement in Maize Belt Areas of Western Ethiopia

Conservation agriculture (CA) relies on soil management systems that include three basic principles aiming to produce high crop yields while reducing production costs, saving labor cost, avoiding crop risk failure, maintaining soil fertility and conserving moisture. On-farm experiments were conducted in two district of Western Ethiopia between 2010-2012. There were six treatments on eight farmers’ field corresponding to different maize-bean cropping systems under CA including conventional practice (CP) for maize as control Rainfall variability and cropping systems with CA significantly affected yield of bean and maize. Significantly higher yield of early maturing haricot bean either planted as sole or intercrops were recorded in 2012 cropping season as compared to late maturing soybean. In high moisture stress season, a significant reduction of both bean and maize yields were recorded. In the rotation system, soybean used as precursor instead of haricot bean significantly improved yield performance of maize. Maize-bean intercropping considerably gave the highest production, increased water use efficiency and maximum net income as compared to crop rotation or continuous production in CA or farmers practices. However, maize-common bean intercrop is better in terms of yield and water use efficiency though soybean-maize intercrops is better in good rainy season. In intercropping systems, delaying bean planting after 25 days of maize planting significantly reduced yield as compared to that obtained after simultaneous planting. CA practices reduced by more than 31-42% total labor time required for ploughing as compared to that under CP. Up to half of labor time for weeding could be reduced due to CA practices. In particular, intercropping had the highest contribution for weed control. Though CA-based maize-bean intercropping followed by sole maize production had the highest net benefit, sole bean production after rotation gave the highest net return per unit cost that could be strategies for sustainable crop production and improvement. Continuous production of legume crops and maize mono cropping reduced soil pH though not significant. However, crop rotation and intercropping in combination with CA improved cation exchange capacity, soil pH, organic carbon and even total nitrogen though not significantly changed. Therefore, intercropping and crop rotation practices could be the best promising technologies that would improve for sustainable production and soil improvement.