Intensifying cropping systems through doubled-up legumes in Eastern Zambia

Declining soil fertility and negative impacts of climate effects threaten the food security of millions in Africa. Conservation Agriculture (CA) is a promising strategy to address these challenges. However, lack of viable economic entry points and short-term benefits for smallholders limit its adoption. Legume intensification can possibly increase the output per unit area, thus making the system more attractive. Rotations of maize with intensified legume systems were tested for three consecutive years under ridge and furrow (RF) tillage and CA to investigate: (a) increases in productivity of legumes and the subsequent maize crop; (b) changes in land equivalent ratios (LERs) and; (c) improved total system productivity. Results showed an increase in legume yields when growing two legumes simultaneously, leading to greater LERs (ranging between 1.13 and 1.29). However, there was only a significant season and not a main treatment effect as CA did not outperform RF in both phases of the rotation. Full populations of companion legumes improved overall system productivity, yielding 76.8 GJ ha(-1) in a more conducive season while sole cropping of pigeonpea yielded only 4.4 GJ ha(-1). We conclude that the doubled-up legumes systems have great potential to improve household food security when integrated into current smallholder farming.

Automated summary

The study found that growing two legumes simultaneously can increase unit area yield and improve overall system productivity, while Conservation Agriculture did not outperform traditional ridge and furrow tillage in the rotation phase. Planting full populations of companion legumes can significantly enhance system productivity.