Research On N₂O Exchange Flux From The Artificial Grassland In Inner Mongolia SEMI-Arid Steppe

N20 fluxes from three different grazing modes(UG, CG, RG) of artificial grassland, Hohhot city, Inner Mongolia,was investigated for a long time,with static opaque chamber/GC method. Based on the measured fluxes, the total exchang of N2O during different seasons and the annual total emission was calculated and analyzde.During the observation period, the net flux of N2O from three different grazing modes of artificial grassland is positive. That is the artificial grassland is the sourse of N2O. The N2O exchange flux of UG is maximum,691.54g N ha-1, followed by RG, 670.27 g N ha-1, CG is minimum,582.00 g N ha-1. But N2O flux of three different grazing modes is not significant difference.Freezing-thawing process significantly promoted the N2O emission rates from three different grazing modes of the artificial grassland, during the winter-spring period which contributed to the annual total emission were UG:38.2%, CG:32.9% RG:44.0%. Although the freezing-thawing period lasted only 2 months (70days), the N2O accumulation flux account for 1/3 of the annual emission.The effect of soil temperature (10cm:T10) on N2O flux from UG and CG is significant. But the correlation relationship of soil temperature (5cm:T5) between N2O flux only the CG reach extremely significant level. For UG and RG the correlation was not significant. The effect of soil moisture(6cm) on N2O flux from the three different grazing modes of artificial grassland is significant(P<0.05).Except the NO3-N concentration in soil of CG did not significantly influence of N2O flux. The effect of NO3--N, NH4+-N and DOC concentration in soil on N2O flux from the three different grazing modes of artificial grassland is significant(P<0.05). Even the effect of NO3--N concentration in soil of UG and the NH4+-N concentration in soil of RG on N2O flux is very significant.