Abstract: N₂O fluxes over a vegetable-growing season were measured in an outdoor pot experiment to identify key soil parameters affecting N₂O emission.Soil samples in the experiment were collected from seven vegetable fields all with more than 10 years of vegetable cultivation in Jiangsu Province and Shandong Province.The experiment had two treatments,urea fertilizer-free （or CK） and urea application.Measurements showed significant differences in N₂O emission between the soils in either treatment.The total amount of N₂O-N emitted during the season ranged from 2.74 to 4.37 mg·pot^-1 in CK,showing a weak linear results with soil pH value,and NH⁺₄-N and NO^-₃-N contents of the soil.Urea application not only enhanced N₂O emission but also expanded the differences in N₂O emission between the soils,increasing the total amount of N₂O-N emitted during the season to the range from 6.39 to 29.38 mg·pot^-1.Though the urea application rate in the vegetable field was less than that in the wheat field in 2000-2001,N₂O emission from the vegetable soils was not significantly decreased.Soil parameters,such as organic carbon,total nitrogen and C/N ratio were identified factors affecting N₂O emissions from the vegetable and the wheat soils when urea was applied.A further investigation indicated that the conversion coefficient of urea N to N₂O-N is exponentially correlated with soil organic carbon and total nitrogen.