Abstract: Daily and seasonal variation of soil N2O fluxes were measured using close chamber method in typical crop fields in Huang-huai-hai Plain. The influence of soil temperature and moisture on soil N2O flux was also discussed. The results showed that the peak value of N2O emission flux appeared in July with 433.5µgN2O•m-2•h-1in winter wheat–summer corn rotation fields, 146.5 µgN2O•m-2•h-1in cotton fields and 175.16 µgN2O•m-2•h-1 in fallow fields. The N2O emission was exponentially correlated with the soil moisture, but it did not happen in wheat–summer corn rotation field. The more N2O emissions also occurred in the fields with higher soil organic matter content.

Key words: N2O, Huang-huai-hai Plain, cropland soils