Molecular Soil Biology 2026, Vol.17, No.1, 12-25 http://bioscipublisher.com/index.php/msb 22 Figure 6 Mechanisms of methane reduction under alternate wetting and drying (AWD) in paddy soils. 7.3 Mitigation potential and implications for sustainable agriculture From the results of broader studies, many meta-analyses have reached similar conclusions: Compared with continuous flooding (CF), alternate wetting and drying irrigation (AWD) generally can significantly reduce CH₄ emissions and also reduce the overall warming potential (Linquist et al., 2015). However, the situation is not entirely uniform. Some studies have also found that N₂O emissions may increase accordingly, and the mitigation effect is also affected by factors such as dryness level, climate conditions, soil organic carbon, and pH (Zhang et al., 2019). For subtropical rice-growing areas, these results generally bring several implications. First, when promoting AWD, a "moderate" or "safe threshold" approach is more suitable, such as lowering the water level to about −15 cm below the field surface before irrigating. This can both ensure emission reduction and more easily guarantee yields. Secondly, AWD is not suitable to be regarded as a single technology. It often needs to be considered together with nitrogen application methods, the time of straw return, and variety selection. Otherwise, problems such as N₂O rebound or unstable substrate supply may occur. Finally, in carbon accounting or policy formulation, regionalized emission factors and standardized monitoring methods should be relied upon, rather than simply promoting the results of a single experimental site. The IPCC also lists "improving rice management" as an important option in agricultural emission reduction measures, which to some extent indicates that rice field water management has both policy significance and methodological value. 8 Discussion and Conclusion From the perspective of ecological processes, alternate wetting and drying irrigation actually seems to be constantly "applying pulses" to the anaerobic system of the paddy field. Each time the field dries out and then is irrigated again, there is a cycle of oxygen entering and then re-oxidizing. The intensity of environmental selection and the resources and electron flow channels also change accordingly. As a result, the microbial organizational pattern originally dominated by a strict anaerobic chain may be disrupted, and the network structure gradually shows more obvious modularization and functional differentiation. However, the complexity of the network does not necessarily mean greater stability. May has already pointed out this point. Therefore, in the study of paddy
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