Abstract

Alternate Wetting and Drying irrigation (AWD) is a water-saving method that involves periodic drainage and re-flooding of rice paddies. This technique has been shown to significantly reduce water usage while mitigating greenhouse gas emissions (GHGs), particularly methane (CH₄). Our study evaluates the effects of AWD irrigation in central Taiwan, focusing on its effects on greenhouse gas emissions in rice paddies. In 2023, the AWD system decreased CH₄ emissions by 41.97% during the first crop and 31.98% in the second season, leading to an annual reduction of 34.29% (3,891.45 kg-CO₂e ha⁻¹). In 2024, this system achieved an overall CH₄ reduction of 17.91% (842.0 kg-CO₂e ha⁻¹). For N₂O, eco-friendly practices resulted in an annual decrease of 60.21% (2,193.0 kg-CO₂e ha⁻¹). A global warming potential (GWP) analysis for the second crop in 2024 showed a 64% reduction (3,970.0 kg-CO₂e ha⁻¹) when water-saving techniques were used compared to conventional methods. These findings highlight the potential of AWD and reduced fertilization strategies to lower global warming potential (GWP), thereby supporting sustainable rice production and GHGs mitigation. Correlations indicated that CH₄ emissions were strongly associated with soil temperature and moisture, while N₂O emissions were highly correlated with soil moisture. Given the limited studies on AWD under non-continuous flooding conditions in Taiwan, this research provided critical insights for optimizing water and nutrient management in rice cultivation and enhancing GHG mitigation efforts.

Keyword: Greenhouse gas emissions, Methane, nitrous oxide, Global Warming Potential