Synergistic Improvement in Wheat Yield, Water and Nitrogen Use Efficiency in Wheat-Maize Rotation Systems: A...

Agricultural practices (APs) comprehensively regulate crop growth; however, comprehensive studies evaluating the effects of APs on crop yield, water use efficiency (WUE), and nitrogen use efficiency (NUE) remain scarce, particularly regarding determining optimal APs for winter wheat in wheat-maize rotation systems. Here, this study conducted a meta-analysis based on 305 studies globally (4009 pairs of observations), focusing on five APs: irrigation, fertilization, tillage, residue utilization, and mulching. And the results indicated that APs significantly increased winter wheat yield (31.1%), NUE (14.7%), and WUE (27.6%), with fertilization showing the most pronounced effects at 43.7%, 16.9%, and 44.7%, respectively. Specifically, compared to no fertilization, combined organic and mineral fertilizer produced the highest yield increase (141.5%); among conventional fertilization, biochar addition showed the best yield increase (19.1%). Slow-controlled/-release fertilizer and inhibitor addition increased NUE by 17.7% and 26.6%, respectively, and residue utilization and mulching improved WUE (by 17.3% and 33.2%). Moreover, in cold and arid regions (mean annual temperature [MAT] < 13 °C and total annual precipitation [TAP] < 550 mm), APs showed stronger promotion of wheat yield and WUE, while in warm and humid regions, the increase in NUE was more significant (15.3-16.1%). When experiment duration was ≥5 years, APs resulted in the highest yield increase (47.9%), while NUE and WUE increased in short-term experiments. Although APs with high nitrogen application rates resulted in a greater yield increase (51.5%), fertilization significantly reduced NUE above 198 kg N ha^-1. Structural equation modeling revealed that, among APs, climatic conditions, soil properties, and management factors, APs were the primary driver of changes in yield and WUE, while NUE was mainly regulated by management factors. Overall, these findings provided an empirical basis for optimizing agricultural practices in wheat-maize systems and offer guidance for developing site-specific policy design.