RESIDUE MANAGEMENT AFFECTS GREENHOUSE GAS EMISSIONS AND SOIL ORGANIC CARBON IN WHEAT-RICE ROTATION SYSTEM

Straw returning is an important factor in taking full advantage of the resources in the agricultural ecosystem. In this study, a field study was conducted to compare the greenhouse gas (GHG) emissions and soil organic carbon (SOC) under different rice (R) and wheat (W) straw returning modes (RDI, rice straw returned in wheat season and WDI, wheat straw returned in rice season) and ditch burying with different depths, viz., 20 cm (RD20 and WD20), 40 cm (RD40 and WD40) and 60 cm (RD60 and WD60) in a wheat-rice rotation system. Ditch burying treatments significantly decreased GHG emissions compared with RDI, while RD40 and RD60 had no significant difference in the total global warming potential (GWP) compared to RCK (no rice straw returning). The SOC and the carbon pool management index (CPMI) with RDI (WDI) were significantly higher than those with the other four treatments in the initial stage after straw returning. However, the difference in SOC and CPMI between R-DI, (WDI) and the other four treatments exhibited a decreasing trend. In addition, ditch burying treatments exhibited no significant difference in the crop yield in relation to CK. This result suggests that in eastern China, straw ditch burying should be a better approach to reducing GHG emissions and improving soil carbon quality without affecting the crop yield.