Optimizing maize–bean cropping systems for sustainable intensification in southern Ethiopia

Declining productivity and scarcity of cultivable land in smallholder systems call for exploring sustainable intensification options to increase productivity. Field experiments were conducted at five sites (Sites 1–5) of the Sidama region, southern Ethiopia, in 2018 and 2019 to determine the effects of cropping systems on maize (Zea mays L.) and common bean (Phaseolus vulgaris L.) productivity. The intercropping of common bean with maize at varying planting times (simultaneous, relay) and number (frequency) of legume intercropping (once or twice) per growing season were compared with monocultures of the components in randomized complete block design with four replications. Cropping system affected the agronomic parameters (pod number plant−1 and 100-seed weight) of common bean, more so than maize. Specifically, the results revealed that cropping systems affected both maize and bean yields, although the magnitude of the effect varied with sites. The highest maize yield was recorded in fertilized monoculture maize at Sites 1, 2, and 5, and in relay and sequential bean intercropping at Sites 3 and 4, respectively. Moreover, the highest bean yields were obtained in double common bean monoculture whereas, the lowest yields were recorded in relay intercropping. The total land equivalent ratio (LER) ranged from 1.2 to 1.8 and partial LER of maize was higher than that of the common bean. Sequential intercropping (Sites 1, 2, and 5) and relay intercropping (Sites 3 and 4) were economically more beneficial than the other cropping systems. Therefore, farmers could benefit more from maize–bean intercropping systems than monocultures in areas where maize is a staple crop.