Supplementary file 1_Sorghum–legume intercropping for sustainable intensification in Sub-Saharan Africa: a systematic review.docx

Here we show that research on sorghum–legume intercropping is concentrated in Eastern (50.7%) and Western Africa (37.0%), with cowpea dominating the evidence base. Cowpea was evaluated in 61.6% of studies, followed by soybean (23.3%), common bean (17.8%), groundnut (15.1%), pigeon pea (9.6%), mung bean (8.2%) and Bambara groundnut (6.8%); individual studies could evaluate more than one legume species. Row intercropping and additive planting designs predominate, particularly the 1:1 (41 studies), 2:1 (18), 1:2 (17) and 2:2 (10) sorghum-to-legume arrangements, although no configuration consistently maximized performance across environments, demonstrating that management recommendations are context-specific.

Land equivalent ratio (LER) values ranged from 0.37 to 3.18, with 34 of the 37 reporting studies (91.9%) recording values greater than one. Reported environmental benefits included increased total soil nitrogen, soil organic carbon and available phosphorus, experimentally measured biological nitrogen fixation of 37.5–164.8 kg N ha⁻¹, and Striga hermonthica reductions of 32.6–99.7%. Quantitative economic analyses, reported in only seven studies, generally indicated greater profitability under intercropping.

Social evidence was limited and focused mainly on dual-purpose grain and fodder production, production stability and farmer participation. However, environmental, economic and social outcomes remained substantially less studied than agronomic productivity. These findings indicate that sorghum–legume intercropping can contribute to sustainable intensification, although its performance depends on crop combination, management and production environment.</p>