Nitrous oxide emissions from three rice paddy fields in China

Nitrous oxide (N2O) fluxes from rice paddy fields were measured in Nanjing, Yingtan and Fengqiu, using closed chamber method in 1994. The results showed that N2O fluxes varied temporally, spatially and geographic regionally, with the total amounts of N2O emissions during the period of rice growth ranged from 13.66 to 98.11 mg/m(2) in Nanjing, 1.73 to 3.65 mg/m(2) in Yingtan and 178.04 to 472.26 mg/m(2) in Fengqiu, respectively. Soil water regime and soil texture had significant effects on N2O production and emission from rice paddy fields. The mean N2O fluxes from sandy, loamy and clayey rice paddy fields were 182.2, 82.8 and 68.7 mu g N2O-N/m(2)/h, respectively. High N2O fluxes occurred when rice paddy fields were imposed by alternation of irrigation and drainage and almost no N(2)0 emitted when the fields were submerged continuously. The rice paddy field applied with ammonium sulphate emitted more N(2)0 than with urea and N2O-N losses of applied ammonium sulphate and urea ranged from 0.038 to 0.28% and 0.033 to 0.16%, respectively.