[Effects of winter cropping mode on soil organic carbon and carbon management index of double rice paddy].

To explore the effects of winter crops recycling into paddy field on soil carbon pool, we cultivated rape, Chinese milk vetch, ryegrass and potato in winter season after harvesting double-season rice, with fallow as control (CK). The contents of soil organic carbon (SOC) and labile organic carbon (LOC) in the harvest of early and late rice were measured, and the stable carbon, activity of carbon pool, carbon pool index, carbon pool activity index and carbon pool management index (CMI) were calculated. Results showed that winter cover crops returning increased SOC content by 1%-8% and 3%-18% after harvest of early rice and late rice, respectively in comparison with CK. Cultivating rape, Chinese milk vetch and ryegrass all increased the LOC content, with enhancement of 16.2%-84.2% and 24.4%-28.1% after harvest of early rice and late rice, respectively. The CMI of all winter crop treatments presented a growth ratio of 1.4%-41.8% compared to CK. In conclusion, the cultivation of winter crop and recycling to field promoted soil carbon fixation and soil quality, among which the ryegrass and Chinese milk vetch showed better comprehensive effect.