Effects of fertilization on soil N₂O flux in Chinese Carya cathayensis stands

N2O fluxes from soil under the Carya cathayensi forest were measured for one year using closed static chamber technique and gas chromatography method. Seasonal variations in N2O flux from managed forestland are related to fertilization and weather conditions. Four different fertilizer treatments with four replicates were set in the field，results showed that N2O fluxes from soil under different fertilization treatments exhibited a strong seasonal pattern, with the maximum values being observed during the summer while the minimum values were observed during the winter. N2O emissions were between -0.021~0.161 mg N/( m2 h), the calculated annual emissions of N2O were OF IF OIF CK , 2.17 kg N /（haa）2.01 kg N /（haa）1.94 kg N /（haa）0.94 kg N /（haa）. It was interesting to note that fertilization treatments increased significantly the emissions of soil N2O (P 0.05) compared with the control. However no significant difference was observed between the others. Additionally, the content of the WSOC and MBC from the OIF and OF treatment had a significantly correlation with the emissions of the soil N2O (P0.05), but there was no significantly correlation between the content of the WSOC and MBC from the IF and CK treatment with the emission of the soil N2O. There was a significant positive relationship between soil N2O emission and the soil temperature at 5cm depth. No significant correlation was found between soil N2O flux and soil moisture. In conclusion， the increase of WSOC caused by organic fertilization was probably one of the important reasons for the increase in N2O emission in the soil of Chinese Carya cathayensis stands induced by fertilization.