Emission factors and global warming potential as influenced by fertilizer management for the cultivation of rice under varied growing seasons.

Abstract

Greenhouse gas (GHG) emissions from paddy fields are intensified during rice production, and are generally reported based on single or double cropping. It needs to be known how emission factors, GHG emission patterns, and global warming potential are affected by growing three rice crops yearly under the principle of integrated plant nutrient system fertilization (IPNSF). Cowdung and vermicompost were used as IPNSF and compared with commercial fertilization alone. A static close chamber technique was used to measure GHG emissions. The peak periods of CH4 emissions were 20-37, 22-42, and 19-38 days after transplanting during dry, wet, and premonsoon seasons, respectively. The use of cow dung significantly enhanced total N2O, CH4, and CO2 fluxes by 5-10%, 15-23%, and 9-20%, respectively, compared to vermicompost. CH4 emissions for each kg grain production were 39-80, 45-63, and 43-57 gm in the dry, premonsoon, and wet seasons, respectively. Vermicompost significantly reduced CH4, CO2, and N2O fluxes by 13-19%, 17-21%, and 4-9%, respectively, along with a reduction in GHG emission factors by 8-17% and global warming potential by 13-17% compared to cow dung. Moreover, vermicompost and cow dung significantly improved rice grain yields in all three growing seasons compared to commercial fertilizer alone. In conclusion, the use of vermicompost as an IPNSF could be a viable technique for improving grain yield and for reducing GHG emissions from paddy fields during year-round rice cultivation.