Effects of micro-sprinkling with different irrigation levels on winter wheat grain yield and greenhouse gas emissions in the North China Plain

Increasing scarcity of irrigation water is threatening global wheat production and sustainability. Accordingly, the water-saving irrigation regime has been strongly advocated to reduce irrigation water consumption. However, studies about greenhouse gas (GHG) emissions from the winter wheat cropping system with water-saving irri-gation are rare. In this study, five irrigation regimes, wherein the supplementary irrigation brought soil water content in the 0-40 cm profile to 65% (K65) field water capacity (FC), 70% (K70) FC, 75% (K75) FC, 80% (K80) FC, and 85% (K85) FC at the joining and anthesis stages in 2019-2022. K75 improved the leaf area index at the grain-filling stage and dry matter remobilization pre-anthesis and dry matter assimilation post-anthesis. Corre-spondingly, 5.48-23.96% increases in grain yield were observed for K75 compared with K65, K70, and K85 treatments, mainly attributable to increased number of kernels and 1000-kernel weight. Compared with the K80 and K85 treatments, K75 treatment had the most prominent effect on the instability of soil carbon, nitrogen, and moisture content, as reflected in decreased cumulative emissions of soil N2O (5.15-15.65%) and CH4 (6.07-44.07%). It also decreased the global warming potential (6.17-19.53%). However, there were no signif-icant differences among K65, K70, and K75 treatments. In addition, the K75 treatment decreased greenhouse gas intensity (GHGI) by 5.04-25.25% compared with K65, K70, K80 and K85 treatments. Collectively, based on the combined effects of grain yield and greenhouse gas emissions improvement, we recommend K75 as a sustainable irrigation regime that can improve grain yield and decrease greenhouse gas emissions.