[Objectives]N_2O is a potent greenhouse gas with global warming potentials (GWP) 298 times greater than that of carbon dioxide (CO_2) on a 100-year horizon. Moreover,increasing atmospheric N_2O is an important factor in stratospheric ozone depletion. As an important component of terrestrial ecosystems,forest ecosystems constitute about 33% of the global land surface,emitting between N_2O-N 2. 4 -5. 7 Tg /yr into the atmosphere. Carya cathayensis is one of the popular nut food tree species in subtropical China. To achieve maximum yield and economic return,chemical and organic fertilizers have been applied in recent years. However,there is little information on the effects of management practices on soil N_2O emissions. The objective of this study was to evaluate the effects of fertilizer application (OF,OIF,IF,CK) on soil N_2O emission from Carya cathayensis orchards in subtropical China.[Methods]A close-chamber method and gas chromatography techniques were used to determine effluxes of N_2O in the four replicate plots of each plot. The static chamber consisted of a permanently installed base box (0. 3 m * 0. 3 m * 0. 1 m) with a U-shaped groove (50 mm wide and 50 mm deep) at the top of edge to hold a removable cover box (0. 3 m * 0. 3 m * 0. 3 m). Both the base and cover boxes were made of dark polyvinyl chloride (PVC) panels,as thick as 5 mm. Prior to gas sampling,the cover box was placed on the base and the groove was filled with distilled water to a depth of 20 mm,acting as an air seal. Gas samples were taken with 60 ml plastic syringes attached to a 3-way stopcock at 0,10,20,and 30 minutes following chamber closure,then injected into evacuated bags made of inert aluminium-coated plastic. N_2O concentration in the samples was analysed in the laboratory using gas chromatography equipped with a electron capture detector (ECD). The temperature of detector was 250℃.[Results]The results showed that N_2O 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. N_2O emissions were between N - 0. 021 ~ 0. 161 mg /(m~2·h),the calculated annual emissions of N_2O were OF > IF > OIF > CK,N 2. 17 kg /(ha·a) > 2. 01 kg /(ha·a) > 1. 94 kg /(ha·a) > 0. 94 kg /(ha·a). It was interesting to note that fertilization treatments increased significantly the emissions of soil N_2O (P < 0. 05) compared with the control. However no significant difference was observed between the fertilizer treatments. Additionally,the content of the WSOC and MBC from the OIF and OF treatments had a significant correlation with the emissions of the soil N_2O (P < 0. 05), but there was no significant correlation between the content of the WSOC and MBC from the IF and CK treatments and the emission of the soil N_2O. There was a significant positive relationship between soil N_2O emission and the soil temperature at 5 cm depth. No significant correlation was found between soil N_2O flux and soil moisture.[Conclusions]Fertilizer application enhanced soil N_2O emission. There was no significant difference between OF, OIF and IF. The increase of soil water soluble organic carbon and microbial biomass carbon caused by organic fertilizer applied might be one of the main reasons that enhanced soil N_2O emission.