Land reclamation increased labile and moderately labile P fractions and strengthened co‐occurrence network of gcd community in calcareous soils

Abstract Land reclamation significantly impacts the transformation and availability of phosphorus (P) in soils. P‐solubilizing microorganisms (PSMs) play key roles in activating soil P. However, the responses of PSMs to the buildup of P under land reclamation and the relationship between different P fractions and PSMs have not been clearly clarified. Here, an investigation was carried out containing three treatments: (i) vegetable field (VF), (ii) cropland (CF), and (iii) uncultivated land (UL). Different P fractions were measured; the abundance of stable oxygen isotope in phosphate of D.HCl‐Pi was determined. The diversity, composition, and co‐occurrence network of P‐solubilizing glucose dehydrogenase community ( gcd ) were analyzed. Compared with the UL treatment, soil total P in the treatments of VF and CF was significantly increased by 1.5 and 1.2 times, respectively. The proportions of labile and moderately labile P in the treatments of VF and CF were 151% and 58% higher than in the UL treatment. The α‐diversity of gcd community (i.e., Shannon and Chao1 indices) in the VF and CF treatments was significantly greater than in the UL treatment. The change in gcd community structure was closely associated with resin‐Pi, NaHCO 3 ‐Pi, and NaOH‐Pi. The nodes and edges in the co‐occurrence networks of VF and CF treatments were higher than in the UL treatment. Overall, a substantial amount of P was accumulated after land reclamation, which was more pronounced by labile and moderately labile P than non‐labile P; the complexity and robustness of gcd community's co‐occurrence network were notably strengthened by land reclamation.