| In order to understand the N2O emission, CH4 absorption , driving forces which control the N2O emission or CH4 uptake rates, and further validate DNDC model in dryland, an automatic sampling system was established to a continous monitoring N2O and CH4. and region simulation and growth seasonal variations research of N2O and CH4 emission or uptake were obtained. The impact of soil temperature, moisture and fertilization on N2O emission and CH4 uptake were analyzed. The main results are as follows:1. The rank of average emission rate of N2O and average uptake rate of CH4 in different growth seasons is flux in winter wheat about late growing stage > flux in soybean about earlier growing stage > flux in soybean about late growing stage. Dryland soil is atmospheric N2O source and is sink of atmospheric CH4.2. N2O emission was relatively increased with the temperature increase when the soil temperature ranges from 10-30 C. But there is no obvious linear relationship between the surface layer soil temperature and N2O emission. There is a lieanr relationship between CH4 uptake rate and soil temperature in the range of 10-20 C. The CH4 uptake rate was decreased when the soil temperature was higher than 20 C.3. N2O emission rate increased linearly with the increase of soil water content when soil water content is lower than field capacity. CH4 uptake rate was no obvious change with the increase of soil water content when soil water content is lower than field capacity.4. Nitrogen fertilization with DCD could mitigate N2O emission, and have no significant effect on CH4 uptake rate.5. DNDC model can well simulate the N2O emission, air temperature and soil surface temperature from soybean growth period although the model has some problems. It can beapplied to simulate N2O emission flux from dryland agroecosystem in Beijing in future. The model can not be applied to simulate CH4 absorption from dryland agroecosystem in Beijing.
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