Polyculture and Food Security in a Variable Climate: A Case Study From Northern Malawi.

Integration of legumes into maize (Zea mays) cropping systems can be an important source of soil fertility in African smallholder agriculture.  Pigeonpea (Cajanus cajan) is a semi-perennial grain legume that fixes more atmospheric nitrogen than it exports in harvested biomass, and is ecologically suitable for integration into maize-based systems in many regions of sub-Saharan Africa.  However, for maize / pigeonpea systems to be of use to food-insecure smallholder farmers, they must be capable of meeting household food needs under a highly variable and changing climate.  We explore the potential of maize / pigeonpea rotations and intercropping systems, as well as sole maize, to meet the calorie and protein needs of smallholder farming households in Ekwendeni, northern Malawi.  We used the Agricultural Production Systems Simulator (APSIM) with multiple decades of climate data to simulate crop production under variable climatic conditions.  By combining crop simulation with surveys of smallholder farming households, we determined the chance of maize / pigeonpea systems and maize monocrop meeting household needs.  We find that maize / pigeonpea intercropping systems are most likely to meet household calorie and protein needs, followed by maize / pigeonpea rotation and maize monocrop.