Ecosystem services in doubled-up legume systems

Abstract Legume-cereal intercropping systems have been practiced on smallholder farms in Africa as part of crop diversification and risk reduction. Alternative systems that accelerate the buildup of soil fertility through large amounts of nitrogen (N)-rich biomass are needed. The doubled-up legume technology is an intercropping system involving two compatible grain legume crops that have different root and shoot growth and architecture. The system is best exemplified by pigeon pea-groundnut intercropping system. The crops are planted at the same time, but the pigeon pea component has a much slower initial growth, resulting in little intraspecific competition. Groundnut matures and is harvested 4 months after planting, leaving pigeon pea to flower as a sole crop and maturing 2–3 months later. This system results in 20%–50% more biological N2-fixation inputs compared with sole cropping. Maize grown in rotations and at 50% of recommended N fertilizer produces comparable yields to full fertilization.