Agronomical performance and sustainability of direct-seeded upland rice–legume intercropping on contrasting tropical soils in the bimodal rainforest zone of Cameroon

Sustainable rainfed rice production is critical for food security and environmental protection in sub-Saharan Africa, where declining soil fertility and intensive tillage limit yields. This study assessed the performance of upland rice intercropped with legumes under direct seeding (no-till) versus conventional tillage in two contrasting soils (Haplic Ferralsol and Dystric Nitisol) in Cameroon’s bimodal rainforest zone. Growth dynamics, dry matter accumulation, nodulation, yield components, and intercropping efficiency indices were quantified to identify optimal soil-cropping system interactions. A split-plot design was used at each site with cropping system (conventional tillage and direct seeding with legume intercropping) as main factor, and rice variety (NERICA 8 and local “rice two months”) alone or intercropped with beans or cowpea) as secondary factor in three replications. Haplic Ferralsol significantly enhanced rice and legume performance, with sprouting > 80%, greater growth traits ( P < 0.05), and grain yields. Direct seeding of Rt intercropped with legumes achieved the highest productivity (Land Equivalent Ratio = 3.67; Monetary Advantage Index = 4.94). Dystric Nitisol’s high bulk density (1.675 kg dm⁻³) suppressed reproduction, though beans formed up to 83 nodules. Dry matter content rose 15–20% under Rt–bean systems. The direct seeding with legume intercropping on Haplic Ferralsol is productive, resource-efficient, and economically viable strategy to strengthen the resilience of rainfed rice production in Cameroon’s bimodal rainforest zone. Not applicable.