Legacy effects of legume-based cropping combined with straw management enhance subsequent wheat yield and improve topsoil quality

Context Integrating legumes into intensive cereal-based cropping systems is crucial for sustainable agriculture. Research question The legacy effects of legume-based diversification (intercropping and rotation) combined with straw management on subsequent wheat yield and soil quality remain poorly understood. Methods A five-year field experiment was conducted in the North China Plain comparing maize–wheat with four legume-based systems including maize/soybean strip intercropping–wheat, maize/peanut strip intercropping–wheat, soybean–wheat, and peanut–wheat rotations, all subjected to two straw management (incorporation vs. removal). Results Legume-based systems increased subsequent wheat yield by 7.8% and showed 21.8% lower adjusted coefficient of variation (aCV) over the four harvest years (2022–2025). The yield advantage becoming more pronounced in later years (e.g., 9.9% in 2024 and 15.9% in 2025). Higher subsequent wheat yield under legume-based systems coincided with greater total dissolved nitrogen (TDN) and available phosphorus (AP), higher nutrient-acquisition enzyme activities, and improved topsoil (0–20 cm) quality. Compared with straw removal, straw incorporation increased the relative wheat yield advantage of the legume-based systems over maize–wheat system by 40.2% and increased their topsoil quality index by 7.3%. Notably, under straw incorporation, variation in topsoil quality index was most strongly associated with microbial biomass and enzyme activities, whereas under straw removal it was more strongly associated with dissolved nutrient availability. Conclusion Integration of legume-based systems with straw incorporation increased subsequent wheat yield and was accompanied by improved topsoil quality. Significance This study highlights the advantages of legume-based systems in increasing subsequent wheat grain yield and their potential contribution to soil quality.