Fertilization type affects the genetic potential for phosphorus mineralization but not for phosphorus solubilization at the continental scale

Conventional and mineral phosphorus (P) fertilizers face depletion risks, but organo-mineral fertilization strategies can reduce P demand in crops. This study examines the long-term effects of applying manure (e.g., sludge, compost) alongside mineral fertilizers (NPKM) on P availability and microbial P cycling in maize and rice agroecosystems across diverse regions of China. We assessed how different fertilization strategies affect soil P availability, phosphatase activity, and the abundance of genes linked to P mineralization, solubilization, transport, and regulation. NPKM treatments significantly increased plant-available P and phosphatase activity, especially in maize, compared to inorganic (NPK) and control (CK) treatments. Enhanced P availability stemmed mainly from microbial-driven P mineralization, indicated by higher phosphatase activity and more abundant P mineralization genes, with no notable impact on P solubilization genes across treatments. Soil pH correlated positively with P solubilization and regulatory processes, highlighting environmental factors' role in P availability and associated microbial processes. Our long-term study demonstrates that combining mineral fertilizers with manure enhances P bioavailability by stimulating microbial mineralization, thereby supporting sustainable P management in agroecosystems.