Greenhouse gas emissions, grain yield and water productivity: a paddy rice field case study based in Myanmar

Climate change is a vital environmental issue that significantly affects rice productivity. Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4) and nitrous oxide (N2O) emissions. To evaluate the combined effects of manure amendment and water management on GHG emissions, grain yield and water productivity per rice yield in a lowland rice field with a sandy clay loam soil in Myanmar, this study was conducted with a split-plot design. Two water management practices (continuous flooding [CF] and alternate wetting and drying [AWD]) and four levels of cow dung manure (0, 2.5, 5.0 and 7.5 t ha(-1)) were applied with three replications in the dry (February-May) and wet (July-October) seasons in 2017. In the dry season, significantly higher cumulative methane (CH4) emissions (50.5%) were recorded in CF than in AWD, while cumulative nitrous oxide (N2O) emissions were 70% higher in AWD than in CF, although the difference was not significant. Manure application showed no effect on CH(4)and N2O emissions compared with the no-manure control, irrespective of application level. In the wet season, significantly higher cumulative CH(4)emissions (65.2%) were again recorded in CF than in AWD; however, the cumulative N2O emissions were similar between CF and AWD. Methane and N2O emissions in the wet season were 65.8 and 35.8% higher, respectively, than those in the dry season. In both seasons, higher grain yields (1.8% in dry and 7.6% in wet) and higher water productivity (130% in dry and 31% in wet) were recorded in AWD than in CF. Increased grain yields (18.9% in dry and 7.7% in wet) and water productivity (25.5% in dry and 15.8% in wet) were recorded in the manure treatments compared to those in the no-manure treatment. This study presents quantitative data on how manure amendment and water management affected GHG emissions in a paddy field in Myanmar. (c) 2020 The Authors.Greenhouse Gases: Science and Technologypublished by Society of Chemical Industry and John Wiley & Sons, Ltd.