Crop rotation and nitrogen management achieve a trade-off among crop productivity, net income and soil CO2 emission in the Hexi Oasis irrigation area

It is critical to the sustainable development of agricultural production that balances between increased grain yield with economic returns and carbon emissions in intensive oasis irrigation agroecosystems. Crop rotation and nitrogen management have been shown to have great potential in enhancing soil carbon sequestration and reducing carbon emissions. However, the comprehensive assessment of different planting systems in terms of crop productivity, economic benefits, soil carbon sequestration and greenhouse gas emissions remains unclear. A continuous field experiment was conducted since 2018 in the Hexi Oasis irrigation area, and data were collected from 2022 to 2025. Four planting patterns (W: spring wheat continuous cropping; WV: spring wheat-common vetch; WWV: spring wheat-winter wheat-common vetch; WRV: spring wheat-winter rapeseed-common vetch) and three nitrogen rates (N2: local conventional nitrogen amount, 360 kg ha −1 ; N1: 270 kg ha −1 , nitrogen amount reduced by 25%; N0: no nitrogen application, 0 kg ha −1 ) were set up as experiment treatments. The results showed that rotation significantly increased equivalent yield compared to continuous cropping. The cropping systems followed a decreasing yield order: WRV> WWV> WV. Compared to the spring wheat continuous cropping with local conventional nitrogen amount (WN2), the wheat-winter rapeseed-common vetch rotation combined with a 25% nitrogen reduction (WRVN1) significantly increased the equivalent yield by 10.7%. Furthermore, WRVN1 increased the soil organic carbon content by 3.9%, organic carbon stock, and carbon management index compared to WN2. In addition, crop rotation reduced carbon emissions (excluding WV), while the carbon emission efficiency of WV pattern was higher than W pattern. The carbon emission efficiency of WRVN1 was 24.2% higher than WN2 and had no significant difference with WRVN2. Furthermore, crop rotation increased net income (excluding WV). And net income of WRVN1 increased by 29.7% compared to WN2. Incorporating winter crops with leguminous green manure and moderate nitrogen reduction can achieve a trade-off between agronomic performance, economic benefits and ecological development in oasis irrigation districts. Our case provides pathways for N management and sustainable production practices in oasis irrigation agroecosystems. ● Diversifying continuous wheat with winter rapeseed and vetch increased system yield and farm net income in the Hexi Oasis. ● Winter crop–legume rotations with 25% less N maintained or increased wheat-equivalent yield while reducing soil CO₂ emissions. ● A spring wheat–winter rapeseed–vetch rotation with less N optimized trade-offs among yield, profit, and carbon sequestration.