Nitrous oxide emission from wetland rice soil as affected by the application of controlled-availability fertilizers and mid-season aeration

N2O emission from a wetland rice soil as affected by the application of three controlled-availability fertilizers (CAFs) and urea was investigated through a pot experiment. N2O fluxes from the N fertilized paddy soil averaged 44.8-69.3 mug N m(-2) h(-1) during the rice growing season, accounting for 0.28-0.51% of the applied N. The emission primarily occurred during the mid-season aeration (MSA) and the subsequent reflooding period. Fluxes were highly correlated with the NO3- and N2O concentrations in the soil water. As there were relatively large amounts of NH4+-N present in the soil of the CAF treatments at the beginning of MSA, leading to large amounts of NO3--N during the MSA and the subsequent re-flooding period, the tested CAFs were not effective in reducing N2O emission from this paddy soil. The potential of applied CAFs to reduce N2O emissions from paddy soil is discussed.