Effects of long-term no tillage and straw return on greenhouse gas emissions and crop yields from a rice-wheat system in central China

Extensive attention has been attracted to no tillage and straw return due to its carbon sequestration and greenhouse gas (GHG) emissions alteration properties. However, the impacts of perceived long-term no tillage and straw return on GHG emissions and crop yields in the rice-wheat system remain unclear. A six-year field experiment was conducted to investigate the temporal impacts of no tillage and straw return on soil organic carbon (SOC), CH4 and N2O emissions, and crop yields. Significant effects of no tillage and straw return on SOC were observed after 5 years of the experiment. The influence of no tillage and straw return on N2O and CH4 emissions and crop yields presented temporal disparities. No tillage significantly increased N2O emission by 28.9%, but reduced CH4 emission by 18.3% during 6-year field experiment relative to conventional tillage. Moreover, no tillage had no significant effect on the annual crop yield. By contrast, straw return remarkably increased N2O emissions, CH4 emissions and annual crop yield by 41.2%, 47.5% and 4.1% over the 6-year field experiment relative to straw removal. Besides, no tillage significantly decreased net global warming potential (GWP) by 27.7%, and had no significant effect on net ecosystem economic budget (NEEB). Inversely, straw return markedly increased the net GWP by 46.2% and the NEEB by 3.4%. Together, these results showed that agricultural strategy of long-term no tillage with straw return is likely to result in low GHG emissions and high crop yields and economic profit in rice-wheat system, suggesting the potential benefit of no tillage with straw return for GHG mitigation and food security.