Long-term optimized tillage with straw return enhances soil health, ecosystem multifunctionality, and rice yield in paddy soils

Sustainable rice production depends on soil health, the foundation of environmental quality and ecosystem services. Conventional tillage without straw return degrades black soils across Northeast China, yet few studies have simultaneously evaluated soil health, soil ecosystem multifunctionality (soil EMF), ecosystem services, and rice grain yield (RGY) under contrasting long-term management regimes. We examined five treatments: conventional tillage without straw return (CT, control), conventional tillage with straw return (CTS), autumn tillage (autumn ploughing plus rotary tillage) with straw return (AT (P+R) S), autumn rotary tillage with straw return (AT (R) S), and autumn rotation tillage (one-year ploughing per one-year rotary tillage) with straw return (AT (P/R) S). Compared with CT, AT (R) S increased the weighted soil health index–minimum data set by 4.24 % and induced positive ΔZ shifts in soil EMF, carbon sequestration, and nutrient recycling of 6.33, 2.12, and 4.38, respectively, accompanied by a 17.96 % increase in RGY driven by improved biological and chemical indicators. Random forest analysis suggested that available phosphorus (AvP), soil organic matter (SOM), and acid phosphatase (ACP) were potential predictors of soil health; AvP, soil urease, and ACP may contribute to soil EMF; and AvP and ACP were important predictors of RGY. Structural equation modeling showed that AT (R) S was positively associated with yield primarily by improving soil health via a biological indicator. AT (R) S emerged as the best-performing treatment for enhancing soil health, soil EMF, and ecosystem services while maintaining high yields, offering new insights for promoting sustainable rice production and soil management in black paddy soils.