4 | CONCLUSIONS
This study supports that no-tillage and straw return are essential for improving SOC stocks, grain yields and agricultural sustainability in the continuous wheat–maize cropping system in the southern Loess Plateau. Soil organic C stocks increased in NT, RT and straw return plots than in CK-SR0 plots with the highest(21.8%) in NT-SR. Straw return, NT, and RT increased grain yields of both wheat and maize, yield stability and sustainable yield index. Combination of conservation tillage (e.g., NT, RT) and maize straw return can substantially increase SOC stocks, yield stability and agricultural sustainability. Moreover, the combinations of no-tillage with wheat straw stubbles 30–40 cm in height and maize straw return was an effective strategy to obtain high SOC stocks, increase grain yields of both wheat and maize and resulted in the optimal agricultural sustainability.