Integrative effects of soil tillage and straw management on crop yields and greenhouse gas emissions in a rice-wheat cropping system

Significant efforts have been made to assess the impact of tillage regimes on crop yields and/or greenhouse gas (GHG) emissions across single crop growing season. However, few studies have quantified the impact across a whole rotation cycle in multiple cropping systems. Utilizing on a long-term tillage experiment with the rice wheat rotation system in East China, we examined the GHG emissions under different tillage practices with or without crop straw incorporation. Results showed that compared to the no-straw control, straw incorporation increased wheat yield by 28.3% (P < 0.05), irrespective of tillage practices, but had no significant effect on rice yield. Although straw incorporation did not significantly affect CH4 emissions during the wheat season and N2O emissions during the whole rice wheat cycle, it significantly stimulated CH4 emissions by 98.8% (P < 0.01) during the rice season. Also, there were no significant differences in CH4 and N2O emissions between tillage practices during the wheat season. Compared to plowing, rotary tillage increased CH4 emissions significantly by an average of 38.8% (P < 0.01) but had no significant impacts on N2O emissions during the rice season. Across the rotation cycle, annual yield-scaled global warming potential of CH4 and N2O emissions under no-tillage plus rotary tillage was 26.8% (P < 0.01) greater than that of rotary tillage plus plowing with or without straw incorporation. Significant interactions between soil tillage and straw management practices were found on annual GHG emissions, but not on crop yields. Together, these results indicate that plowing in the rice season plus rotary tillage in the wheat season may reduce GHG emissions while increasing crop yield in rice wheat cropping areas. (C) 2014 Elsevier B.V. All rights reserved.