Regenerative benefits of legume–wheat intercropping systems on soil quality and resource-use efficiency under deficit irrigation in Egypt
Abstract
Soil degradation and water scarcity are major constraints to sustainable cereal production in arid and semi-arid regions. Legume–wheat intercropping may simultaneously improve soil quality and resource-use efficiency, but its regenerative performance under deficit irrigation remains insufficiently quantified. A two-year field experiment was conducted during 2021/22 and 2022/23 in El-Minia Governorate, Middle Egypt, using a split-plot design with three replications. Three irrigation regimes—100%, 85%, and 70% of crop evapotranspiration (ETc)—were evaluated in combination with sole wheat and wheat intercropped with faba bean, pea, or fahl clover. Soil organic matter, available N, P, and K, soil pH, Soil Quality Index (SQI), crop yield, land equivalent ratio (LER), water equivalent ratio (WER), and change in water use (DWU) were assessed. All legume–wheat intercropping systems significantly improved soil organic matter and available macronutrients relative to sole wheat. Faba bean–wheat generally produced the greatest improvements in soil properties and SQI. The beneficial effects of intercropping persisted under severe deficit irrigation (70% ETc). Pea–wheat achieved the highest total LER (1.39) and WER (1.26), together with the highest wheat grain yield and a DWU of -20.48%. Legume–wheat intercropping enhanced soil quality, land-use efficiency, and water-use efficiency under deficit irrigation. The results demonstrate that integrating legumes with wheat can provide a practical regenerative strategy for improving productivity and resilience of wheat-based systems in water-limited environments.