Straw and residual film management enhances crop yield and weakens CO(2) emissions in wheat–maize intercropping system

Higher CO(2) emissions and lower crop productivity are becoming thorny problems and restricted sustainable development of agriculture in arid inland areas. Intercropping has been shown to enhance crop productivity. However, Intercropping generally requires more input that led to an increase in CO(2) emissions. It is unknown whether designing tillage and film mulching in reduction could decrease soil CO(2) emissions in intercropping. Therefore, we integrated no tillage combined with residual film mulching and straw returning into wheat–maize intercropping. The maximal soil CO(2) fluxes (F(s)) with intercropping was decreased by 12–21% compared to sole maize. Residual film mulching combined with straw returning (NTSMI) significantly reduced average F(s) during the entire period of crop growth by 14–15%, compared with the conventional tillage (CTI). Soil CO(2) emissions (CE) with intercropping was 18–20% less than that with sole maize and the NTSMI reduced CE by 12–16% compared to the CTI. The NTSMI boosted total grain yields (GY) by 14–17%, compared with the CTI. Wheat–maize intercropping significantly enhanced soil CO(2) emission efficiency (CEE) by 33–41% in comparison to sole maize, and CEE with NTSMI was increased by 29–40% than that of CTI. A quadratic function for aboveground biomass (BA) combined with two linear functions for soil temperature (T(s)) and soil water-filled pore space (WFPS) was suitable for the monitored results. A multiple regression model composed of the above three factors can explain 73–91% of the F(s) variation. Crop biomass accumulation at the time of maximal F(s) was less with intercropping compared with sole maize. The structural equation indicated that the BA synergistic effect on CEE through combining negative effects on CE and positive effects on GY in intercropping. In conclusion, no tillage with straw returning and residual film mulching in wheat–maize intercropping was confirmed to be an optimum management practice to reducing soil CO(2) emissions and enhancing soil CO(2) emission efficiency in arid inland agroecosystem.