While rice production may need to increase to keep pace with the growing demand, efficient and sustainable management is needed to mitigate methane emissions from rice paddy fields, which still contribute substantially to the global methane budget. Field mid-season drainage is a popular water management strategy that reduces emissions by shortening the period of time the field spends in anaerobic conditions; however, it is still unclear how drainage timing affects its overall effectiveness. Here we combine observations from field experiments with a methane emission model to analyze how the time at which the field is drained controls the reduction in methane emissions. We show that an optimal drainage timing maximizes the mitigation efficiency of the drainage, defined as the reduction in methane emissions due to a mid-season drainage relative to the emissions in a continuous flooding management. We then estimate maximum mitigation efficiencies and optimal drainage timings across the experiments and shed light on the role of organic amendment. The average optimal drainage timing for organically amended fields is earlier than for non-amended ones (20 and 50 days after transplanting, respectively), promoting an average CH₄ emissions reduction of about 45% and 35%, respectively. The potential increase in mitigation efficiency obtained by optimizing drainage timing highlights the important role of this strategy in a sustainable management of rice cultivation, where rice yield and N₂O emissions may impose further constraints on water management.

尽管可能需要增加稻米产量以跟上不断增长的需求，但仍需要有效和可持续的管理来减轻稻田产生的甲烷排放，这仍然为全球甲烷预算做出了巨大贡献。田间季间排水是一种流行的水管理策略，可通过缩短田间在厌氧条件下的时间来减少排放。然而，目前尚不清楚排水时间如何影响其整体效果。在这里，我们将田间试验的观察结果与甲烷排放模型结合起来，以分析田间排空的时间如何控制甲烷排放量的减少。我们显示最佳的排水时机可最大程度地提高排水效率，定义为相对于连续洪水管理中的排放，由于季中排水而减少的甲烷排放量。然后，我们估算了整个实验过程中的最大缓解效率和最佳排水时间，并阐明了有机改良剂的作用。有机改良田的平均最佳排水时间要早于非改良田（分别在移植后20天和50天），从而促进了平均CH的排放。_4种排放量分别减少了约45％和35％。通过优化排水时间可以潜在地提高缓解效率，这突出表明了该策略在水稻种植可持续管理中的重要作用，因为水稻产量和N ₂ O排放量可能对水管理施加进一步的限制。