Maintenance of Maize Yield and Soil Fertility With Hairy Vetch Intercropping but Reduction by Rye Versus Maize Monoculture

ABSTRACT Monoculture maize threatens food security by reducing yields and depleting soil fertility. Incorporating unharvested forage grasses into maize fields through intercropping, offers a promising strategy to stabilize grain production while simultaneously enhancing soil health. However, it remains unclear how cover crop species and the intercropping period affect cereal yield and soil fertility. In this study, maize yield, soil physicochemical properties and enzyme activity were measured under maize monoculture, and maize‐hairy vetch ( Vicia villosa Roth ) and maize‐winter rye ( Secale cereale ) intercropping within the intercrop sown either concurrently with maize (S1) or at maize two‐leaf stage (S2) in 2022 and 2023. We found that hairy vetch maintained maize yield whereas winter rye significantly decreased maize yield by 18.4% compared with 2‐year maize monoculture. Intercropping with hairy vetch and winter rye decreased soil bulk density, and increased soil particle porosity, available N and potassium levels and urease and catalase activity. Compared to maize monoculture, intercropping with hairy vetch significantly enhanced the soil total nitrogen content and invertase activity. Furthermore, intercropping with hairy vetch and winter rye significantly improved the soil fertility index, which was higher at S1 than that at S2. A 2‐year field experiment indicated that intercropping of hairy vetch maintained maize yield and enhanced soil fertility with intercrop sowing at S1. These findings are valuable for the broader adoption of intercropping to maintain crop yields, improve soil fertility and support long‐term sustainability.