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利用长期稻草还田定位试验和短期不同稻草还田模式试验,研究稻草还田对南方双季稻田土壤固碳、甲烷排放和综合碳汇的影响.结果表明:稻草还田能增加土壤有机碳,长期还田的耕层土壤碳汇年增长率为0.07tC.hm-2.a-1,土壤有机碳的表观转化率随着稻草还田量的增加而减少.稻草还田导致稻田甲烷排放量显著增加,其中,NPK添加稻草(NPK+RS)处理早、晚稻期间甲烷排放通量比仅施NPK分别增加了75.0%和251.5%(P<0.01).稻田甲烷排放随着稻草还田量的增加而增加,在水稻产量和耕作方式相近的条件下,稻草(茬)的甲烷表观转化率接近.综合土壤固碳和甲烷排放的稻田净碳汇,NPK+RS处理负碳汇效应显著,基本与其水稻生物固碳接近,比稻草不还田处理(NPK)增加158.3%;不同还田模式中,稻草覆盖免耕处理能显著减少甲烷排放,其净碳汇(负值)比高桩翻耕处理减少50.9%,有利于水稻高产稳产.
The effects of straw incorporation on soil carbon sequestration, methane emission and carbon sequestration in paddy fields of southern China were studied using long-term straw locating experiments and short-term different straw returning patterns.The results showed that straw incorporation increased soil organic carbon, The annual growth rate of carbon sink in long-term topsoil was 0.07tC.hm-2.a-1, and the apparent conversion of soil organic carbon decreased with the increase of straw returning amount. (NPK + RS) increased the methane emission flux by 75.0% and 251.5% (P <0.01) compared with that of NPK alone (P <0.01) , The apparent conversion rate of straw (stubble) is close to that of rice under the similar conditions of rice yield and tillage method.The combination of NPK + RS and NPV + , Which is almost the same as the carbon fixation rate of rice and 158.3% higher than that of non-return treatment of straw (NPK). In different return patterns, no-tillage treatment with rice straw can significantly reduce methane emission and its net carbon sink (negative value) Plowing reduction of 50.9%, is conducive to high and stable yield of rice.