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 (CH 4 ) and nitrous oxide (N 2 O) 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 (CH 4 ) emissions (50.5%) were recorded in CF than in AWD, while cumulative nitrous oxide (N 2 O) emissions were 70% higher in AWD than in CF, although the difference was not significant. Manure application showed no effect on CH 4 and N 2 O 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 N 2 O emissions were similar between CF and AWD. Methane and N 2 O 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. © 2020 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons, Ltd.