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To understand the role of microbial processes in phosphorus (P) immobilization in a weathered subtropical soil, the effects of application of a phosphate-solubilization microorganism strain (Pseudomonas sp. 2VCP1) on P availability in soil, dynamics in microbial biomass P (Bp), microbial biomass C (Bc) and Olsen-P were investigated during a 60-d laboratory incubation. The included treatments were P. sp. inoculums at×106？cfu·g？1 soil (CKM); glucose at 5？g·kg？1 soil (G); G with P. sp. inoculum (GM); rice straw at 5 or 10？g·kg？1 soil (5S or 10S); 5S and 10S with P. sp. inoculum (5SM and 10SM). The results indicated that the amount of soil Bc increased about 3.2, 1.7, and 2.6 times for G, 5S and 10S compared to the control (no organic amendment and P. sp.; CK), respectively. The amount of soil Bp for G and 10S almost doubled during the first 7？d, then remained relatively steady. The amount of Olsen-P in G, 5S and 10S showed a significant decrease (0–5.4？mg P·kg？1 soil) during the 60-d incubation compared to CK. However, changes in soil Bp between the treatments inoculated with P. sp. (CKM, G, 5SM, 10SM) and the uninoculated controls (CK, G, 5S, 10S) were not significant during the 60-d incubation period, whereas a small increase in Bp of the GM treatment was seen up to day 11. The amount of soil Bc in CKM, GM, 5SM and 10SM had increased but not greater than 20% compared to their corresponding uninoculated control. The amount of Olsen-P increased but not greater than 0.88？mg P·kg？1 soil. The result illustrated that there were a few effects on soil P immobilization following inoculation with P. sp. in the soil, whereas organic amendments can significantly motivate the soil native microorganisms to immobilize phosphorus. |
