Optimizing tillage practice based on water supply during the growing season in wheat and maize production in northern China

Optimizing tillage practices to improve crop yield and crop water productivity (CWP) is essential for promoting sustainable dryland agriculture. This meta-analysis used the water supply during the growing season (WS, total soil water storage at sowing time, and growing-season precipitation) instead of mean annual precipitation (MAP), to assess the effects of different tillage practices on the yield and CWP of winter wheat and spring maize in northern China. The results showed that WS had a stronger correlation with crop yield than MAP, especially for winter wheat. Compared with conventional tillage, no-tillage combined with straw mulching (SM) increased winter yield by 36.56 % and CWP by 17.93 % when WS ≤ 650 mm, and subsoiling tillage increased winter wheat yield by 21.17 % and CWP by 9.29 % in winter wheat yield when WS > 650 mm. SM and subsoiling tillage performed better in regions with higher mean annual temperature (MAT) than that with lower MAT. For spring maize, no tillage, no-tillage combined with plastic film mulching (PM), subsoiling tillage and rotary tillage significantly increased yield and CWP under different WS conditions and the highest effect was showed in PM under higher WS condition; meanwhile, PM and subsoiling tillage performed good under various temperature conditions, while rotary tillage performed better in areas with lower temperature. Thus, the recommended tillage practice for spring maize is PM in northeast China, and subsoiling tillage in north-central and northwest China; for winter wheat, subsoiling tillage is recommended for north-central China, and SM is recommended for northwest China. Taken together, our results indicate that it is more accurate to use WS rather than the MAP to evaluate appropriate tillage practices in drylands. Furthermore, WS can also replace MAP for yield estimation and prediction.