秸秆还田模式对农田土壤碳库特性及产量的影响

为探明南方稻麦两熟制农田秸秆还田模式对土壤总有机碳、活性有机碳、碳库管理指数和稻麦产量的影响,论文通过8 a的水稻-小麦轮作田间定位试验,设置了4个秸秆还田模式处理：秸秆不还田（CK）、秸秆稻麦季均还田（RW）、仅麦秸稻季还田（W）、仅稻秸麦季还田（R）。结果表明,与CK处理相比,秸秆还田显著提高了0~20 cm土壤的总有机碳、活性有机碳、稳定态有机碳（P<0.05）;不同秸秆还田模式处理之间的土壤总有机碳、稳定态有机碳差异均不显著（P>0.05）,RW处理的活性有机碳、碳库活度指数、碳库管理指数与R处理无显著差异性（P>0.05）,显著大于W处理（P<0.05）;RW与R处理的水稻产量均值无显著差异性（P>0.05）,显著大于W处理;活性有机碳、碳库管理指数与水稻产量均值呈极显著相关（P<0.01）,与小麦产量均值关系不密切（P>0.05）;上述结果表明,与稻麦两季还田模式相比,南方稻麦两熟制农田实施仅稻秆麦季还田模式,并不影响作物稳产性与土壤地力的提升。

Effects of Patterns of Returning Straw to Field on Soil Carbon Pool and Yield in Rice-wheat Double Cropping Systems

Straw returning helps to decrease the environment pollution, moreover, the rational utilization of straw resources benefits sustainable development of soil fertility, soil conservation, and the agricultural ecosystem. An eight-year field experiment was conducted in Suzhou City, Jiangsu Province to study the effect of different patterns of straw returning to field on labile organic (LOC), carbon pool management index (CPMI) and crop yields in a typical rice-wheat rotation region—the Taihu Lake region. The experiment consisted of four patterns of returning straw to the field: rice straw alone (named as “R”), wheat straw alone (named as “W”), straw of both rice and wheat (named as “RW”) and no straw returning to field (CK). The results indicated that returning straw significantly increased the content of total organic carbon (TOC), LOC, and non-labile organic (NLOC) at the soil depth of 0-20 cm interval compared to no straw returning treatment. The TOC significantly increased by 15.34%-16.97%, and the LOC content significantly increased by 16.62%-27.39% (P<0.05). No significant difference on TOC or NLOC was observed among different treatments. There were no significant differences of LOC, CPI, CPMI between the treatments of RW and R, while the value of LOC, CPI, CPMI of RW were higher in the treatment of W. The mean rice yield increased by 4.53% in RW and 4.07% in R treatment respectively compared to CK treatment (P<0.05), and no significant difference was observed between W and CK treatments. There were no significant differences of LOC between RW and R treatments (P>0.05), while significant differences were observed between the treatments of RW and W (P<0.05). LOC and CPMI were significantly correlated to the mean yield of rice (P<0.05), while they were not correlated with mean yield of wheat (P>0.05). It was concluded that compared with the mode of returning both rice and wheat straws to field, the mode of only returning rice straw to field in the wheat growing season does not affect the crop yield stability and soil fertility improvement. However, it is recommended to reduce or avoid returning wheat straw in a rice-wheat double cropping system in South China.