What do we really know about the impacts of improved grain legumes and dryland cereals? A critical review of 18 impact studies
Improved grain legume and dryland cereal (GLDC) varieties hold potential to intensify smallholder agriculture and improve livelihoods in semi-arid regions of sub-Saharan Africa and South Asia. To assess the empirical evidence base for these potential benefits, we review 18 GLDC impact studies and identify gaps in current knowledge on GLDC impacts. Results from this synthesis reveal that all five reasonably well-identified adoption studies estimate significant, positive effects of improved GLDC adoption on yields, profits, or household welfare. Another well-identified study focuses on nutritional impacts of improved GLDC consumption and measures positive effects on iron-deficiency in school children. Macro-level welfare estimates based on economic surplus models (eight of the 18 studies) are largely invalidated because of their dependence on poorly-identified household-level impact estimates. Four additional studies rely on correlations and expert interviews. Overall, impact studies focus on chickpea and groundnut, as opposed to other GLDC crops. Studies are geographically concentrated in Ethiopia, India, and Tanzania, and are heavily focused on estimating economic impacts, with few studies assessing potential environmental, nutritional or social impacts. Recommendations are offered to improve methodological approaches in future impact assessments of GLDC crops.