The project has identified actual and potential legume productivity in East-Africa for the major producing areas.

Legume productivity in East-Africa

Opportunities exists for introducing legumes in food production systems in Sub-Saharan Africa (SSA), because legumes diversify food intake and have a high nutritional value. In addition, inclusion of legumes in cereal cropping systems can increase cereal yields, due to their capability of fixing atmospheric N. Therefore, inclusion of legumes in the cropping systems is climate smart, as they may enhance productivity at given mineral nitrogen fertilizer rates. Yield gap assessment provides insight in opportunities to increase productivity of legume crops. Yield gap is the difference between the yield which farmers actually obtain and the potential yield. For the yield potential we use the water-limited yield potential, which is the yield with optimal crop growth (i.e. optimal soil management, no nutrient deficiencies, and no yield reductions by weeds, pests and diseases), but water can be limiting as no irrigation is assumed. Within the Global Yield Gap Atlas (GYGA, yieldgap.org), the yield gaps for several cereal crops (e.g. maize, sorghum, millet, rice, wheat) in SSA have already been determined and mapped. We investigated the yield gaps of the main legume crops in East-Africa for the major producing areas and scaled-up the results from locations to country level, following the GYGA protocols, and compared differences between countries.

We focused on the main legume crops in East-Africa. For Ethiopia these were common bean (Phaseolus vulgaris L.); Kenya: pigeon pea (Cajanus cajan L.); Tanzania: common bean, chickpea, cowpea (Vigna unguiculata L.), pigeon pea and groundnut (Arachis hypogaea L.). Results can be accessed via the GYGA website, yieldgap.org.

Fig. 1 The relative yield gap (ReYg, i.e., actual yields as a percentage of the water-limited potential) per country for chickpea, common bean, cowpea, groundnut, and pigeon pea

The relative yield gap (i.e., actual yields as a percentage of the water-limited potential) of most legumes in the three countries is large, i.e. between 68% and 88% (Fig. 1). In absolute terms, yield gaps of all these legume crops in the three countries vary between 1.6 t/ha and 2.6 t/ha. We thus identified actual and potential legume productivity, and those results will be used to devise climate-smart maize-legume practices in East-Africa for a range of stakeholders and users, including extension agencies, agri-business (incl. fertilizer industry) and social enterprises.

Nanyan Deng1 & Marloes van Loon2

1 University of Nebraska Lincoln, United States 2 Plant Production Systems, Wageningen University & Research, The Netherlands