Field Crop 2025, Vol.8, No.3, 154-165 http://cropscipublisher.com/index.php/fc 154 Research Insight Open Access Impact of Alternate Wetting and Drying (AWD) Irrigation on Rice Yield and Greenhouse Gas Emissions Dapeng Zhang Hier Rice Research Center, Hainan Institute of Tropical Agricultural Resources, Sanya, 572025, Hainan, China Corresponding email: dapeng.zhang@hitar.org Field Crop, 2025, Vol.8, No.3 doi: 10.5376/fc.2025.08.0015 Received: 18 Apr., 2025 Accepted: 29 May, 2025 Published: 21 Jun., 2025 Copyright © 2025 Zhang, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Zhang D.P., 2025, Impact of alternate wetting and drying (AWD) irrigation on rice yield and greenhouse gas emissions, Field Crop, 8(3): 154-165 (doi: 10.5376/fc.2025.08.0015) Abstract The optimization of rice field irrigation methods is of great significance for alleviating water resource shortages and reducing agricultural greenhouse gas emissions. This study systematically reviews the impact of alternating dry and wet irrigation (AWD), a water-saving irrigation technology for rice, on rice yield and greenhouse gas emissions from paddy fields. The results show that AWD effectively reduces methane emissions from rice fields through periodic dry-wet alternations, significantly reducing methane flux by 20% to 70%, while only accompanied by a slight increase in nitrous oxide emissions. Moderate AWD treatment (such as a soil water potential threshold of approximately-15 kPa) will not significantly reduce rice yield. In some cases, it can promote root development and improve nitrogen use efficiency, thereby achieving stable and increased yields. Excessive drought stress (such as soil water potential below-30 kPa) may inhibit root growth and photosynthesis, leading to a significant decrease in yield. Both field trials and large-scale demonstrations have demonstrated that implementing AWD while ensuring yield can save 25% to 30% of irrigation water, enhance water use efficiency and reduce irrigation costs. The promotion of AWD helps to reduce the comprehensive warming potential of rice fields and achieve emission reduction and efficiency improvement in rice production. This article simultaneously discusses the adaptability and limitations of AWD in different ecological regions, its synergistic effect with other low-carbon agricultural measures, and looks forward to future research directions and policy support priorities. Research suggests that the scientific implementation of AWD technology is of great significance for ensuring grain production, conserving water resources, and reducing greenhouse gas emissions in the field of rice production. Keywords Alternating dry and wet irrigation; Rice yield; Methane emissions; Nitrous oxide; Water use efficiency 1 Introduction More than half of the world's population regards rice as their staple food. However, growing rice consumes a lot of water, with irrigation alone accounting for over 30% of agricultural water usage. Nowadays, water resources are becoming increasingly tight. The traditional rice fields that are always submerged for cultivation are indeed finding it hard to sustain. But then again, saving water is not that simple-you have to consider the output and also take the environment into account. Moreover, perhaps many people are not aware that rice fields are also a major source of greenhouse gases: being constantly flooded can easily produce methane, and if they are sometimes dry and sometimes wet, they will release nitrous oxide (Towprayoon et al., 2005). In some rice-growing countries, methane emissions from rice fields can account for about 10% of the total agricultural emissions, which is really a considerable proportion (Khalil and Shearer, 2006). So now, ensuring the harvest while reducing the emissions caused by rice cultivation has become a core challenge for the sustainable development of rice planting. Especially in the context of promoting carbon neutrality in agriculture, this issue has become even more urgent. Traditional rice cultivation always involves soaking in water. Although this can suppress weeds, it consumes a lot of water and also generates a large amount of methane due to soil oxygen deficiency. The mid-term sun-drying of fields commonly used in Asia can strengthen roots and prevent lodging, but it does little to help reduce emissions. Alternating wet and dry irrigation (AWD), which has become popular in recent years, is a good approach. It alternates between flooding and draining, allowing the soil to breathe air from time to time. This can effectively inhibit methanogens and reduce methane emissions by an average of 30% to 50% (Zhao et al., 2024). Although this might lead to a slight increase in nitrous oxide emissions, the overall reduction effect is still very prominent
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