| Aiming at the problems of soil fertility decline and greenhouse gas emission increase caused by long-term continuous cropping of wheat and excessive use of nitrogen fertilizer in Hexi oasis irrigation area, the effects of different rotation modes and nitrogen reduction on spring wheat yield, farmland CO2, N2O emission and soil enzyme activity were studied, in order to clarify the dynamic changes of farmland CO2 and N2O emission under the condition of rotation combined with nitrogen reduction and its relationship with spring wheat yield and soil enzyme activity, so as to provide theoretical basis for the green and efficient development of local agriculture. Based on the field positioning test in Wuwei Oasis Agricultural Experimental Station in 2018, four planting patterns were set up : spring wheat-winter rape-common vetch ( WRV ), spring wheat-winter wheat-common vetch ( WWV ), spring wheat-common vetch-spring wheat-common vetch ( WV ), and spring wheat continuous cropping ( W ). Two nitrogen application levels, traditional nitrogen application ( 360 kg·hm-2, N2 ) and nitrogen reduction 25% ( 270 kg·hm-2, N1 ), were used to measure and analyze the effects of different rotation modes combined with nitrogen reduction on farmland CO2 and N2O emissions and their relationship with soil enzyme activities from 2020 to 2021. The results showed that rotation combined with nitrogen reduction treatment could significantly reduce greenhouse gas emissions and increase crop yield. The WRVN1 treatment had the best effect on increasing yield and reducing emissions. Compared with WN2 treatment, the total emissions of CO2 and N2O decreased by 15.2% and 28.0%, respectively, GWP and GHGI decreased by 15.7% and 30.4%, respectively, and crop yield increased by 16.7%.The activities of urease and catalase in 0~10 cm soil layer were higher than those in 10~30 cm soil layer. At the flowering stage of wheat, rotation reduced the activity of soil enzymes, among which the soil enzyme activity of WRVN1 rotation mode was the lowest. Under the condition of reduced nitrogen application, the activities of soil urease and catalase decreased by 20.1% -28.7% and 8.3% -12.2%, respectively, and the emission rates of CO2 and N2O were significantly positively correlated with the activities of soil urease and soil catalase. In summary, the spring wheat-winter rapeseed-common vetch ( WRV ) rotation mode combined with 25% nitrogen reduction can be used as a reasonable planting mode and nitrogen application system to achieve regional agricultural efficiency and emission reduction. |