Effects of alternate wetting and drying technique on greenhouse gas emissions from irrigated rice paddy in Central Luzon, Philippines

ABSTRACTAlternate wetting and drying (AWD) technique has been widely reported to reduce methane (CH4) emission from irrigated rice paddies. However, little is known about its feasibility in an environment that has distinct weather conditions involving tropical wet season (WS). To investigate the AWD’s feasibility in terms of reducing greenhouse gas (GHG) emissions both in dry season (DS) and WS, 3-year field experiments were conducted in Central Luzon, Philippines. Three treatments of water management were continuous flooding (CF), flooding when surface water level naturally declines to 15 cm below the soil surface (AWD), and site-specific AWD that modified the criteria of soil drying (AWDS). Methane and nitrous oxide (N2O) fluxes were measured using a closed chamber method, and the global warming potential (GWP) of the two GHGs was calculated. Rice grain yield did not significantly differ among treatments. In accordance with the previous findings, the seasonal total CH4 emission was significantly greater...