Fig. 1. Soil characteristics, phosphorus (P) fractions, microbial community compositions, and relative quantitative values of P functional genes under different treatments. A, Soil pH values in different treatments. B, Soil available P contents in different treatments. C, Effect of different treatments on P content of various soil forms shown as percentages. D, Redundancy analysis (RDA) reveals linkages among soil P fractions, soil properties, bacterial α diversity (ACE, Abundance-based coverage estimator), and microbial community compositions. The red arrows indicate soil properties, blue arrows indicate different forms of P, black arrows indicate bacterial α diversity, and purple arrows indicate dominant bacteria. E, RDA reveals linkages among soil P fractions, soil properties, bacterial α diversity, and P-cycling pathway gene families. The red arrows indicate soil properties, blue arrows indicate different forms of P, black arrows indicate bacterial α diversity, and purple arrows indicate P-cycling pathway genes. F, Soil bacterial community compositions at the level of phylum in different treatments. G, Soil bacterial community compositions at the level of common dominant phyla in different treatments. H, Relative quantitative expression of phoD and phnK genes in soils under different treatments. I, Relative quantitative expression of gcd and pqqC in soils under different treatments. J, Relative quantitative expression of phoX gene in soils under different treatments. CK, No fertilization; RHB1, 0.5% rice husk biochar (RBH) and 0.1% organic fertilizer (OF); RHB2, 1.0% RBH and 0.1% OF; BMB1, 0.5% Bacillus megaterium (BM)-inoculated RBH (BMB) and 0.1% OF; BMB2, 1.0% BMB and 0.1% OF; Pi, Inorganic P; Po, Organic P. Data are Mean ± SD (n = 3). Different lowercase letters in the same columns indicate significant differences (P < 0.05).

Table 1. The α diversity index of soil bacteria under different treatments.