Carbon-phosphorus stoichiometric imbalance induced by manure amendment enhances microbial phosphorus mobilization and crop phosphorus uptake

• P-based manure amendments cultivated higher soil C:P stoichiometric ratio. • Manure amendments shifted microbial community assembly toward copiotrophic dominance. • Microbial C:P imbalance induced by increased soil C:P ratio is a key driver of MBP accumulation and turnover. • Maize yield and P uptake benefits from increased soil C:P ratio. Fertilization alters soil stoichiometric ratios, shaping microbial processes and phosphorus (P) dynamics, yet the underlying mechanisms remain poorly understood. Here, we conducted a three-year maize field experiment on the North China Plain, to test how P-based manure amendments modified soil C:P ratio, intensified microbially mediated soil P mobilization and turnover processes, and improved crop P uptake and yield. There were four treatments as follows: P0, no P fertilizer; P1, 39.27 kg ha −1 of chemical P; LCP, with a total P input of 39.27 kg P ha −1 , input 0.76 t ha −1 manure C; and HCP, with a total P input of 39.27 kg P ha −1 , input 1.53 t ha −1 manure C. Our results suggested that manure C inputs significantly increased the content of soil dissolved organic carbon (DOC) and induced a shift in microbial community composition from oligotrophic (Acidobacteria) to copiotrophic taxa (Proteobacteria, Bacteroidetes, Myxococcota), accompanied by increased microbial biomass P. Manure amendment significantly raised the soil C:P ratio, but the microbial C:P ratio remained relatively stable across treatments. The induced C:P imbalance intensified microbial P limitation, exerting selective pressure on soil microbes preferential investment in P mobilization. Through the coordinated regulation of microbial community composition and function, manure amendment enhanced the bioavailable P pool and increased plant P acquisition. By increasing soil C:P ratios relative to full chemical fertilization, P-based manure amendment increased maize yield by 12%, improved P fertilizer recovery efficiency from 81.34% to 97.06%, enhanced P fertilizer utilization efficiency from 22.01% to 36.69%, and reduced soil P accumulation from 7.35 to 1.15 kg P ha −1 year −1 . These findings suggest that manure-induced stoichiometric imbalance triggers a priming effect on indigenous microbial P mobilization, providing an ecologically intensive pathway to enhance fertilizer P use efficiency, reduce environmental P loading, and improve crop productivity.