Global meta-analysis shows that microbial inoculants enhance soil phosphorus availability and plant performance primarily through accelerated phosphorus turnover

Phosphorus (P) limitation constrains plant productivity, yet much of the soil phosphorus remains locked in poorly available forms. Microbial inoculants are widely promoted as a biological strategy to improve P availability, but their effects on soil P pools and P-cycling processes remain inconsistent across studies. Here we conducted a global meta-analysis of 308 studies comprising 3007 observations to quantify inoculation effects on soil available P (AP), phosphatase activity, and total P (TP), and to identify the environmental and management factors governing these responses.