Abstract：The soil CH4 and N2O emission fluxes from the natural meadow-steppe grassland and reclaimed grassland under different crop planting and management measures were investigated during the growing seasons in 2012 and 2013 at Xieertala pasture, Hulunber, Inner Mongolia. The results showed that both the natural grassland and reclaimed grassland played a role as a sink for CH4 and a source for N2O. The conversion of natural grassland to cropland increased N2O emissions from the soil in growing seasons, however, there was a large uncertainty in the impact on soil CH4 fluxes. There was no difference in CH4 and N2O emission fluxes for different crop types under same meteorological conditions. Irrigation had no clear effect on CH4 average uptake fluxes in growing seasons, but significantly reduced N2O average emission fluxes. The differences in CH4 and N2O fluxes for 2012 and 2013 were mainly caused by the inter-annual precipitation variability. The correlation analysis and stepwise linear regression revealed that the soil CH4 and N2O emission fluxes were significantly correlated with soil moisture, the CH4 fluxes were also in linear relationship with soil temperature.
