Enhancing soil phosphorus (P) availability is crucial for the sustainable utilization of nonrenewable P fertilizer resources. Straw return was found to influence soil P availability; however, its magnitude and governing factors across large geographical areas remain largely uncertain. To address this knowledge gap, we conducted a global meta-analysis of 477 field experiments from 181 sites worldwide. We showed that straw return significantly enhanced soil available P and crop P-uptake by 12.8% and 15.0%, respectively. Soil pH was identified as the most important factor. With increasing soil pH, both response indices decreased in acidic soils, whereas they increased in alkaline soils. This concave relationship was attributed to the fact that straw return increases pH in acidic soils but decreases it in alkaline soils. Our study presents the first integrative assessment of straw return-induced enhancement in soil P availability at a global scale, providing new insights into the sustainable utilization of crop straw and P fertilizer resources.
