No-tillage mulch with green manure retention can mitigate carbon emissions, increase crop productivity, and promote agricultural sustainability

Wheat–maize rotation, as a typical planting mode in arid irrigation areas, has some disadvantages, such as a low resource utilization rate and high carbon emissions (CEs), which seriously limits green and sustainable agricultural development. It is unclear whether green manure can be properly incorporated into a wheat–maize rotation system to improve agricultural sustainability while achieving yield increases, higher efficiency, and emission reductions. A field experiment was carried out at an arid oasis region in northwestern China from 2019 to 2022. The five treatments were treated as follows: (i) conventional tillage and leisure (CT), (ii) no-tillage mulch with green manure retention (NTG), (iii) no-tillage and removal of above-ground green manure (NT), (iv) tillage in which green manure is mixed with soil (TG), and (v) tillage in which green manure is partially removed from the ground and roots are incorporated into the soil (T). In this experiment, the effects of different green manure return methods on maize yield, water use, and CE-related parameters were investigated to evaluate the sustainability of different green manure return methods. We found that compared with CT, NTG and TG increased the maize grain yield (GY) by 26.1 % and 26.7 %, maize energy yield (EY) by 19.8 % and 18.8 %, water use efficiency based on grain yield (WUE_GY) by 35.1 % and 30.8 %, and water use efficiency based on energy yield (WUE_EY) by 29.3 % and 22.5 %, respectively. Compared with CT, the CEs of NTG were reduced by 7.4 %, and the carbon emission efficiency (CEE) increased by 28.8 %. In addition, NTG increased soil carbon sequestration potential (NPP/CE) while increasing net primary productivity (NPP), net ecosystem productivity (NEP), and carbon sequestration (CS). The sustainability evaluation index (SI) of NTG was the highest among the different green manure return methods. Therefore, no-tillage mulch with green manure retention can be used as a recommended green manure return method for green, sustainable production in arid oasis irrigated areas.