Methane and nitrous oxide emission from Kharif rice field as influenced by nutrients and moisture regimes in new alluvial agroclimatic region of West Bengal

Crop management practices have a significant impact on greenhouse gas (GHG) emission rates, where methane (CH4) and nitrous oxide (N2O) emissions from rice paddy fields are in trade-off association. A field study for two consecutive years (2013 and 2014) was conducted to continuously measure CH4 and N2O emissions from rice paddies under various agricultural management schedules like water regimes (irrigated and rainfed), transplanting dates and nutritional amendments (synthetic fertilizer with N as ammonium sulphate, P and K according to recommended dose, and vermicompost). Rainfed situation incurred a drop in CH4 fluxes triggering substantial N2O emission. Ammonium sulphate application tended to reduce CH4 emissions, but significantly increased N2O emissions. Enhanced CH4 fluxes were measured during panicle initiation to flowering stage while, maximum N2O emissions were recorded during flowering to milking stage of rice crop. Significant interrelationship between the gases was evaluated. In addition, seasonal average of CH4 and N2O emissions was also correlated with rice production. In conclusion, GHG concentration may control to some extent optimizing rice productivity through implementing and improving crop-and location-specific management practices.