Straw incorporation is strongly recommended in rice paddy to improve soil quality and mitigate atmospheric carbon dioxide (CO2), via increasing soil organic carbon (SOC) stock. However, straw application significantly increased methane (CH4) emission during rice cultivation, and then its incorporation area was not expanded effectively. To find the reasonable straw management practice which can reduce CH4 emission without productivity damage, the effect of straw incorporation season and method on CH4 emission was investigated at six different textured paddy fields in South Korea for 2 years. A straw was applied right after rice harvesting in autumn, and the other right before rice transplanting in spring. In the autumn application, straw was applied with two different methods: spreading over soil surface or mixing with soil. Straw application significantly increased seasonal CH4 flux by average 28–122% over 197–590 kg CH4 ha−1 of the no-straw, but its flux showed big difference among straw applications. Fresh straw application before transplanting increased seasonal CH4 flux by approximately 120% over the no-straw, but the autumn application reduced its CH4 flux by 24–43% over 509–1407 kg CH4 ha−1 of the spring application. In particular, the seasonal CH4 flux was approximately 24% lower in straw mixing with soil after autumn harvesting than 423–855 kg CH4 ha−1 in straw spreading over surface. However, CH4 fluxes were not significantly discriminated by soil and meteorological properties in the selected condition. Straw application slightly increased rice grain yield by approximately 4% over the no-straw, but rice productivity was not statistically different among straw applications. Spring straw application increased CH4 intensity which means seasonal CH4 flux per grain yield by the maximum 220% over the no-straw. Autumn straw application significantly decreased CH4 intensity by average 24–65% over the spring straw application. In particular, CH4 intensity in straw mixing with soil treatment was not statistically different with the no-straw. Therefore, autumn straw application with mixing inner soil could be a reasonable straw management practice to decrease CH4 emission impact with improving soil productivity.

中文翻译：

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秸秆还田对稻田甲烷排放的影响：转化因子和智能秸秆管理

强烈建议在稻田中加入稻草，以通过增加土壤有机碳（SOC）的含量来改善土壤质量并减轻大气中的二氧化碳（CO2）。然而，稻草的施用显着增加了水稻种植过程中甲烷（CH4）的排放，因此其吸收面积没有得到有效扩大。为了找到可以减少CH4排放而又不损害生产力的合理秸秆管理实践，在韩国六个不同的稻田中研究了秸秆掺入季节和方法对CH4排放的影响，为期2年。秋季水稻收获后立即使用稻草，春季水稻移植之前则使用稻草。在秋季施用中，用两种不同的方法施用秸秆：在土壤表面铺展或与土壤混合。秸秆施用显着增加了季节性CH4的通量，比无秸秆的197–590 kg CH4 ha-1多了28-122％，但秸秆施用的通量显示出很大的差异。移栽前施用新鲜秸秆比不施秸秆增加了季节性CH4通量约120％，但秋季施用比春季施用509-1407 kg CH4 ha-1减少了CH4通量24-43％。特别是，秋季收获后的秸秆与土壤混合时，季节性CH4通量比散布在地表的秸秆中的423–855 kg CH4 ha-1低约24％。但是，在所选条件下，CH4通量不能通过土壤和气象特性明显区分。施用秸秆比不施用秸秆可使稻谷产量略微提高约4％，但是稻草的应用在稻米生产上没有统计学差异。春季秸秆施用增加了CH4的强度，这意味着每粒产量的季节性CH4通量比无秸秆时最多增加220％。与春季秸秆施用相比，秋季秸秆施用显着降低了CH4强度，平均降低了24-65％。尤其是，秸秆还田与土壤处理的CH4强度与无秸秆在统计学上没有差异。因此，秋季秸秆还田与内部土壤混合可能是减少CH4排放影响并提高土壤生产力的合理秸秆管理实践。与春季秸秆施用相比，秋季秸秆施用显着降低了CH4强度，平均降低了24-65％。尤其是，秸秆还田与土壤处理的CH4强度与无秸秆在统计学上没有差异。因此，秋季秸秆还田与内部土壤混合可能是减少CH4排放影响并提高土壤生产力的合理秸秆管理实践。与春季秸秆施用相比，秋季秸秆施用显着降低了CH4强度，平均降低了24-65％。尤其是，秸秆还田与土壤处理的CH4强度与无秸秆在统计学上没有差异。因此，秋季秸秆还田与内部土壤混合可能是合理的秸秆管理实践，以减少CH4排放的影响并提高土壤生产力。