Effects of tillage systems on greenhouse gas emission of wheat-maize double cropping system in North China Plain

Greenhouse gas (GHG) emissions from agro-ecosystem have been widely concerned as a hot issue. Tillage methods significantly affect GHG emissions in the farmland. This study was conducted on double cropping system of winter wheat and summer corn in North China with four treatments (conventional tillage CT, conventional tillage with straw retention CTS, no-tillage with straw retention NTS, rotary tillage with straw retention RTS). In order to study tillage effects on field GHG emissions, CO2, N2O and CH4 emissions fluxes were collected. Results showed that soils of each the treatment were net sources of CO2, but RTS and NTS consumed atmospheric CH4, while N2O emission exhibited high annual flux in all the treatments except RTS; soil moisture contents in NTS were maximum (19.3%) and significantly higher compared to the other treatments (at P<0.05 level); CO2 emission fluxes (g CO2 m(-2) y(-1)) were generally in the order of CTS (6460.3) > CT (5568.4) > RTS (5421.2) > NTS (4200.1); integrated evaluation of field greenhouse effect indicated that it was mainly caused by CO2, with CH4 and N2O as subsidiary components; total greenhouse effect under different tillage treatments was followed NTS < RTS < CT < CTS in North China Plain.