Straw enhanced CO2 and CH4 but decreased N2O emissions from flooded paddy soils: Changes in microbial community compositions.

To explore microbial mechanisms of straw-induced changes in CO 2 , CH 4 , and N 2 O emissions from paddy field, wheat straw was amended to two paddy soils from Taizhou (TZ) and Yixing (YX), China for 60 d under flooded condition. Illumia sequencing was used to characterize shift in bacterial community compositions. Compared to control, 1–5% straw amendment significantly elevated CO 2 and CH 4 emissions with higher increase at higher application rates, mainly due to increased soil DOC concentrations. In contrast, straw amendment decreased N 2 O emission. Considering CO 2 , CH 4 , and N 2 O emissions as a whole, an overall increase in global warming potential was observed with straw amendment. Total CO 2 and CH 4 emissions from straw-amended soils were significantly higher for YX than TZ soil, suggesting that straw-induced greenhouse gas emissions depended on soil characteristics. The abundance of C-turnover bacteria Firmicutes increased from 28–41% to 54–77% with straw amendment, thereby increasing CO 2 and CH 4 emissions. However, straw amendment reduced the abundance of denitrifying bacteria Proteobacteria from 18% to 7.2–13% or increased the abundance of N 2 O reducing bacteria Clostridium from 7.6–11% to 13–30%, thereby decreasing N 2 O emission. The results suggested straw amendment strongly influenced greenhouse gas emissions via alerting soil properties and bacterial community compositions. Future field application is needed to ascertain the effects of straw return on greenhouse gas emissions. [ABSTRACT FROM AUTHOR]