Methane emission from paddy soils as affected by wheat straw returning mode

To study influence of wheat straw returning mode on CH4 emission from paddy soils, a field experiment was conducted at Jurong, Jiangsu Province, China in 2006. Five treatments, no wheat straw applied (CK), wheat straw evenly incorporated into the topsoil (WI), wheat straw buried in ditches (WD), wheat straw strip-mulched onto the field surface (WM) and wheat straw burned in-situ (WB), were laid out in a randomized block design. Results showed that seasonal CH4 emissions ranged from 6.9 to 28.1 g CH4 m(-2). Wheat straw incorporation significantly increased CH4 emission. No significant difference was observed between Treatments WI and WD in total CH4 emission. Compared with Treatment WI, Treatment WM reduced total CH4 emission by 32% and Treatment WB by 42%. Treatment WM was about 27% higher than Treatment CK in grain yield. Based on the findings, the best management of wheat straw prior to rice cultivation is strip-mulching wheat straw onto the field surface, which largely reduced CH4 emission from rice fields with no decrease in rice yield.