Soil and Fertilizer Institute of Hunan Province, Hunan Academy of Agriculture Science, Changsha, China.
J Sci Food Agric. 2012 Mar 30;92(5):1038-45. doi: 10.1002/jsfa.5550. Epub 2012 Jan 6.
Soil organic carbon (SOC) sequestration, methane emission, and the net carbon sink represented by rice straw incorporated into soil (RIS) were studied using long-term experimentation with rice straw incorporated into soil (LRIS) and short-term experimentation with different patterns of rice straw incorporated into soil (SPRIS).
Soil organic carbon could be improved by RIS combined with soil ploughing. The increased rate of SOC deposition per cultivated layer was 0.10 t C ha(-1) for 2.625 t ha(-1) straw incorporated each season in LRIS and 0.36 t C ha(-1) for 4.5 t straw ha(-1) season(-1) incorporated in SPRIS; the apparent SOC conversion by rice straw (stubble) was reduced as the amount of incorporated straw increased. However, RIS methane emission from paddy fields also significantly exacerbated the CH(4) emission flux observed during the early and late rice growing seasons, which was increased by 75.0% (P < 0.01) and 251.5% (P < 0.01), respectively, compared with combined application of nitrogen, phosphorus and potassium fertiliser (NPK). The apparent methane conversion of straw was almost uniform with a similar rice yield and soil cultivating mode. Among the patterns of RIS, methane emission was significantly reduced under straw covering untilled land, and this property led to the lowest apparent methane conversion.
RIS with ploughing and tilling resulted in negative carbon sequestration because of increased methane emissions. A combined NPK application with only rice stubble incorporation may be sustainable for a higher rice yield, but this approach has a reduced rate of negative carbon sequestration in the paddy field. Straw covering with no tillage was the best measure to realise high yield and low carbon emission for RIS.
采用长期稻草还田（LRIS）和短期不同稻草还田方式（SPRIS）试验，研究了土壤有机碳（SOC）固持、甲烷排放和稻草还田引起的土壤净碳汇（RIS）。
稻草还田结合耕翻可提高土壤有机碳。LRIS 中每季 2.625 t ha(-1)和 SPRIS 中每季 4.5 t ha(-1)稻草还田，使耕层土壤有机碳（SOC）沉积速率分别增加了 0.10 t C ha(-1)和 0.36 t C ha(-1)；随着还田量的增加，稻草（茬）表观 SOC 转化量降低。但稻田 RIS 甲烷排放使早稻和晚稻生长季 CH(4)排放通量分别显著增加 75.0%（P < 0.01）和 251.5%（P < 0.01），比氮磷钾（NPK）配施还田处理分别增加了 75.0%（P < 0.01）和 251.5%（P < 0.01）。稻草表观甲烷转化量受相似的水稻产量和耕翻方式影响，较为一致。在 RIS 不同方式中，稻草不耕翻覆盖处理甲烷排放量最低，表观甲烷转化量最低。
稻草还田并耕翻导致甲烷排放增加，引起负碳固持。仅还田稻茬而不配施 NPK 可能有利于水稻更高产量，但降低了稻田负碳固持率。稻草不耕翻覆盖是实现 RIS 高产量和低排放的最佳措施。
