Response of greenhouse gases emissions and yields to irrigation and straw practices in wheat-maize cropping system

Global water shortages and appropriate crop residues management are the major issues threatening the sustainable development of agriculture, food security, and the environment. In this study, we conducted a one-year field experiment (in 2020–2021) to investigate annual yield, greenhouse gas (GHG) emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) in a wheat-maize cropping system. Straw practices were kept in the main plot, including straw incorporation (SI) and straw removal (SR). Irrigation practices were allocated into sub-plots, including surface drip irrigation (DI), sub-surface drip irrigation (SDI), partial rootzone irrigation (PRI), and flood irrigation (FP). All treatments were fertilized at the level of 210 kg N ha–1 for each season. The soil acted as a net sink for CH4 but as a source of N2O emissions during the annual crop growth period under all irrigation treatments. The highest direct GHGs, net GWP, and GHGI were found in FP compared with all other irrigation practices under SI or SR. SI significantly increased annual yield (5.0%), CH4 emission (17.1%) and ΔSOC (119.9%), but decreased N2O emissions (19.4%) and GWPd (19.6%), thus resulting in a net GWP reduction of 23.6% as compared to SR under SDI. Additionally, the best treatment for minimizing the negative environmental impacts was found in SDI, which reduced net GWP by 39.7% (P < 0.05), and decreased GHGI by 43.0% (P < 0.05) as compared to FP under SI. We conclude that sub-surface drip irrigation combined with straw incorporation simultaneously mitigates GHG emissions, improves yield, and enhances soil C sequestration, making it a suitable environment-friendly agricultural management practice for sustainable farming in northern China.