Sorghum–legume intercropping for sustainable intensification in Sub-Saharan Africa: a systematic review

Abstract

Sub-Saharan Africa faces declining soil fertility, increasing climate variability and persistent food insecurity, highlighting the need for production systems that increase productivity while maintaining environmental sustainability. Sorghum–legume intercropping has long been promoted as a climate-resilient strategy, yet evidence on its management and contribution to sustainable intensification has not been systematically synthesized. This is the first systematic review to evaluate sorghum–legume intercropping across Sub-Saharan Africa within an integrated sustainable intensification framework encompassing agronomic, environmental, economic and social dimensions. Studies published between 2000 and 2025 were systematically identified using predefined eligibility criteria. Information on management practices, geographical distribution, and productivity, environmental, economic and social outcomes was extracted and synthesized using a narrative approach because of substantial methodological heterogeneity among studies. 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.