Long-term straw return enhanced crop yield by improving ecosystem multifunctionality and soil quality under triple rotation system: An evidence from a 15 years study

Objective Rice-rice-oilseed rape rotation is a typical triple cropping system in Asia, and the development of rice-oilseed rape rotation plays an important role in ensuring global food and oil security. With the intensive cropping rotation and frequent changes between paddy and upland farming under anaerobic and aerobic conditions, whether tillage and straw return would be benefit for both agronomic and environmental perspectives remained to be tested. Method Therefore, we used a long-term locational experiment (15 years) employing four treatments of conventional tillage without straw incorporation (CT); conventional tillage with straw incorporation (CTS); no-tillage without straw mulching (NT); no-tillage with straw mulching (NTS), to assess the relationships among soil quality, ecosystem multifunctionality, and crop yields under the straw-returning and tillage strategies, based on both agronomic and environmental perspectives. Result The results showed that long-term straw return to the field could increase the yield of early rice by 6.24–8.80%, late rice by 3.81–7.13%, and oilseed rape by 9.55–14.45%. Long-term straw return enhanced soil quality index (SQI) by 22.21–40.74% and ecosystem multifunctionality (EMF) by 104.19–141.14% in the 0–20 cm soil layer. Long-term conventional tillage (i.e., CT and CTS) showed higher SQI and EMF values especially in the oilseed rape season. Structural equation modelling (SEM) indicated that straw return and tillage mainly increased crop yield by increasing the SQI in the oilseed rape season. Conclusion In conclusion, long-term straw return with conventional tillage would be more benefit for the improvement of soil quality and the multifunctionality of soil ecosystems under triple paddy-upland rotation system, offering an effective approach for sustainable soil management and crop production.