Phosphorus (P) runoff loss in agroecosystems is known to be soil-dependent. While the physicochemical processes of P runoff have been extensively studied, there is a lack of research on its microbial effects. This study investigated variations in P runoff loss, soil P fractions, and microbial biomass (MB) across 11 different agricultural treatments in a long-term positioning experiment of double-cropping rice cultivation. Results revealed a P-deficient state in the paddy soil, with an average total soil P content (TSP) of 0.55 g kg