Effect of rice cultivars, organic manures, and water management on methane emissions and grain yield

Abstract To assess the effect of different organic manures and rice cultivars on methane emissions, a pot experiment was conducted at the Yezin Agricultural University, Nay Pyi Taw, Myanmar during the wet season of 2016. Organic manures (control, compost, and cow dung) and two rice cultivars (Manawthukha and IR 50) were tested. For both rice cultivars, high grain yield was observed in the control, and the minimum grain yield was observed in the cow dung treatment. The rate and cumulative CH 4 emissions in Manawthukha were higher than those in IR 50, in accordance with the yield, because of the longer growth duration. Although not significant, the lowest methane emissions were observed in the cow dung manure treatment (0.808 g CH 4 kg −1 soil) against the control (0.893 g CH 4 kg −1 soil) and compost (0.951 g CH 4 kg −1 soil) treatments. Based on these results, a field experiment was conducted at Madaya Township, Mandalay region, Myanmar during the dry and wet seasons of 2017 to determine the effects of water management and different rates of cow dung manure on methane emission and yield of IR 50. Higher methane emissions were recorded for continuous flooding (CF) than for alternative wetting and drying (AWD). In both seasons, higher grain yields (1.8% in dry and 7.6% in wet) were recorded for AWD than for CF. Higher methane emissions were recorded from OM 3 and lower emissions from OM 0 in both water management practices. In AWD, methane emissions were restricted under aerated soil conditions, although a higher amount of manure was added.