Maize yields from rotation and intercropping systems with different legumes under conservation agriculture in contrasting agro-ecologies

Abstract

Maize (Zea mays L.) is a key food security crop in Eastern and Southern Africa (ESA). Maize yield gaps are large in the smallholder farming systems of ESA but can be closed by a combination of improved crop varieties and sustainable cropping systems. On-farm trials were conducted in five countries of ESA over a seven-year period to assess the effects of different cropping systems on maize productivity. Cropping systems tested were conventional practice (Conv_sole) compared with variants of conservation agriculture (CA) such as sole maize (CA_sole), intercropping (CA_intercropping) and rotation (CA_rotation). Maize yield varied with cropping system and agro-ecological conditions. In highlands, CA_intercropping (3709 kg ha−1) outperformed Conv_sole (3456 kg ha−1), CA_sole (3596 kg ha−1) and CA_rotation (3545 kg ha−1) with similar legumes in the cropping system. The CA_rotation (3050 kg ha−1) out-yielded the other treatments (2645−2864 kg ha−1) in lowlands where similar legumes were grown in the cropping system. Without rotation practices, CA_sole (3596 kg ha−1) outperformed the conventional and CA_intercropping treatments (2954−3036 kg ha−1) in highlands with similar legumes in the cropping system. In lowlands, CA_intercropping (2802 kg ha−1) out yielded the other treatments (2485−2658 kg ha−1). The highest maize yield was from CA systems with groundnut (3609 kg ha−1) and common bean (3307−3576 kg ha−1) under rotation and intercropping practices, respectively. Maize-pigeon pea intercropping (35 %) and maize-groundnut rotation (31–43 %) under CA had the highest maize yield advantages over the conventional practices. The most stable maize yields were from the maize-common bean systems under CA. There is scope for promoting CA cropping systems integrated with grain and forage legumes to address maize productivity challenges on smallholder farms of ESA.