The Impact of Alternate Wetting and Drying (AWD) on Methane Emissions and Groundwater Recharge in Organic Paddy Fields

Rice paddies are one of the major sources of methane emissions among greenhouse gases. Traditional conventional irrigation practices keep paddy fields flooded for extended periods, creating anaerobic soil conditions that promote significant methane emissions. In recent years, with the intensification of climate change, the global challenge of water resource management has become increasingly prominent. Alternate Wetting and Drying (AWD) has been recognized as a sustainable irrigation practice that not only reduces water usage but also decreases methane emissions. However, while conserving water, AWD may alter water infiltration patterns in fields, potentially affecting groundwater recharge. This study investigates the effects of AWD and conventional irrigation on methane emissions and groundwater dynamics in organic paddy fields located at the Taoyuan District Agricultural Research and Extension Station in Taiwan. The research was conducted in two organic experimental fields. Methane emissions were measured using a gas analyzer, while tensiometers, soil moisture sensors, and electrical resistivity tomography (ERT) devices were installed in the AWD field to monitor soil moisture dynamics. Observation wells equipped with water level loggers were also set up near the fields to collect groundwater level data. The results showed that AWD significantly reduced methane emissions compared to conventional irrigation, confirming that agricultural water-saving practices can effectively mitigate methane emissions. Furthermore, through the analysis of groundwater levels in relation to irrigation and rainfall data, the study found that both irrigation and rainfall had a notable impact on groundwater recharge.