Field Crop 2024, Vol.7, No.4, 232-242 http://cropscipublisher.com/index.php/fc 235 4 Benefits of Alternating Wetting and Drying 4.1 Water conservation and efficiency Alternating Wetting and Drying (AWD) is a water management practice that significantly reduces water usage in rice cultivation. Studies have shown that AWD can reduce total water inputs by 25-70% compared to the conventional continuously flooded (CF) system (Ishfaq et al., 2020). In China, optimized AWD methods decreased irrigation water usage by 40% while increasing water productivity by 34% (He et al., 2020). Additionally, AWD systems have been reported to use 11.88% and 3.79% less water during the wet and dry seasons, respectively, compared to CF (Sriphirom et al., 2019). This reduction in water use is crucial for regions facing water scarcity and helps in the sustainable management of water resources. 4.2 Yield stability and crop performance AWD not only conserves water but also maintains or even improves rice yields. For instance, mild AWD has been shown to increase rice yields by 1-6% compared to CF (He et al., 2020). Complete AWD during the dry season enhanced rice yield by 2.42% through increased tiller and panicle numbers (Sriphirom et al., 2019). Furthermore, the combination of AWD with appropriate nitrogen management (e.g., polymer-coated urea) has been found to synergistically increase grain yield and resource use efficiency (Zhang et al., 2021). These findings suggest that AWD can provide stable or improved crop performance while conserving water. 4.3 Reduction of greenhouse gas emissions One of the significant environmental benefits of AWD is the reduction in greenhouse gas (GHG) emissions, particularly methane (CH4). AWD can reduce CH4 emissions by 11-95% compared to CF (Ishfaq et al., 2020). In a meta-analysis, non-continuous flooding practices, including AWD, reduced CH4 emissions by 53% (Jiang et al., 2019). Additionally, optimized AWD methods in China reduced GHG emissions by 37% through lower methane emissions and less energy consumption from irrigation (He et al., 2020). Although AWD can increase nitrous oxide (N2O) emissions, the overall global warming potential (GWP) is still lower than that of CF (Jiang et al., 2019; Sriphirom et al., 2019). 4.4 Soil health and nutrient management AWD positively impacts soil health and nutrient management. It improves soil aeration, which enhances root growth and canopy structure (Mubeen and Jabran, 2019). AWD also reduces the accumulation of heavy metals such as arsenic and mercury in rice grains, thereby improving grain quality and safety (Ishfaq et al., 2020). Moreover, AWD has been shown to increase the concentration of grain micronutrients like zinc (Ishfaq et al., 2020). The practice of AWD, combined with appropriate fertilization strategies, can enhance nutrient use efficiency and reduce the environmental footprint of rice cultivation (Zhang et al., 2021). 4.5 Economic benefits for farmers The economic viability of AWD is another critical benefit. By reducing water and energy inputs, AWD lowers the cost of irrigation, making it a more cost-effective option for farmers (He et al., 2020; Ishfaq et al., 2020). In China, the economic return from optimized AWD methods could largely offset the risk of yield losses (He et al., 2020). Additionally, AWD can increase farmers' income by maintaining or improving yields while reducing input costs (He et al., 2020). The adoption of AWD can thus provide significant economic benefits, contributing to the overall sustainability and profitability of rice farming. In summary, AWD offers multiple benefits, including water conservation, yield stability, reduction in GHG emissions, improved soil health, and economic advantages for farmers. These benefits make AWD a promising alternative to conventional rice cultivation practices, particularly in regions facing water scarcity and environmental challenges. 5 Challenges and Limitations of AWD 5.1 Adoption barriers Adoption of the Alternate Wetting and Drying (AWD) technique faces several barriers. One significant barrier is the lack of institutional support and the complexity of agricultural and socioeconomic systems, which can hinder
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