Improving long‐term crop productivity and soil quality through integrated straw‐return and tillage strategies

Abstract Long‐termagricultural sustainability receives increasing concerns owing to the inappropriate removals of crop straw with frequent tillage, causing soil degradation and reduced productivity. A 7‐yr field experiment was conducted to exploit the optimal integrated straw‐return and tillage strategy for maintaining soil quality and sustaining crop productivity in an intensive wheat (Triticum aestivum L.)–maize (Zea mays L.) cropping system in the Guanzhong Plain. Three strategies were tested for wheat: straw harvest (Wh), straw return with chopped straw distribution on soil surface (Wr) and with stubble 30–40 cm height (Ws); three strategies were for maize: straw harvest with rotary tillage (Mh), straw return with rotary tillage (Mr) and with subsoiling (Ms). Thus, nine integrated strategies were conducted per rotation period: WhMh, WhMr, WhMs, WrMh, WrMr, WrMs, WsMh, WsMr, and WsMs. The results indicated that the eight integrated strategies (except WhMh) promoted both wheat and maize grain yields, and showed the largest increase for the system productivity (+42.3%) and sustainable yield index (+43.0%) under WsMs relative to the WhMh. In addition, significant increases were observed in various soil quality indicators under integrated strategies, especially under WsMs. The system productivity responses were predominately determined by mean weight diameter, soil organic carbon, available nitrogen, and available phosphorus. Therefore, the integrated strategies of wheat straw return with stubble 30–40 cm height and maize straw return with subsoiling can be advised for maintaining soil quality and improving crop productivity in the wheat–maize cropping system in the long term.