Reduction of Global Warming Potential from rice under alternate wetting and drying practice in a sandy soil of northern Italy

Methane (CH4) is the dominant greenhouse gas (GHG) implicated in global warming from paddy fields, with emissions largely controlled by water and residue management practices. The permanent flooding-based conventional cultivation system is an important anthropogenic source of atmospheric CH4. However, rice fields also emit N2O, especially in relation to N fertilization, and N2O emissions tend to increase when management practices are implemented to reduce CH4 emissions, through the use of alternate wetting and drying (AWD). Reducing CH4 and N2O emissions from rice cropping systems with less water input without compromising the grain yield is a challenge that requires a better understanding of the key processes involved, in particular under Mediterranean pedo-climatic conditions. This work aimed to assess the effect of AWD application on CH4 and N2O emissions, global warming potential (GWP) and grain yield in selected Italian rice fields. The GWP was larger under permanent flooding (PF) than AWD both during the whole growing season and the flooding period. However, a significant yield decrease was observed under AWD system, suggesting that site specific management options should be carefully planned taking into account the main drivers affecting mitigation potential under AWD water-saving rice production.