Biosolubilization of phosphorus from rock phosphate and other P fertilizers in response to phosphate solubilizing bacteria and poultry manure in a silt loam calcareous soil

摘要

Phosphate solubilizing bacteria' (PSBs) are able to release unavailable P from native and applied P sources into plant-available soil pool through their solubilizing and acidifying effects. The effects of three indigenous and one exotic PSBs on P solubilization from different P sources, plant biomass production, and P-uptake efficiency of maize (Zea mays L.) were examined in an incubation and greenhouse study. For incubation study, surface (0-15 cm) soil was collected from an arable field (Inceptisols) and amended with rock phosphate (RP), single superphosphate (SSP), poultry manure (PM), and RP+PM with and without PSBs. The amended soil was incubated in the control environment at 25 +/- 2 degrees C for a total of a 100-d period to establish relative potential rate of P solubilization of added P sources. A complementary greenhouse experiment was conducted in pots by growing maize as a test crop. Growth characteristics, P-uptake, and P-utilization efficiency (PUE) were determined. Phosphate solubilizing bacteria generated a solubilization effect on different P sources by releasing more P into plant-available soil pool, i.e., 14.0-18.3 mu g g(-1) in RP, 5.0-9.9 mu g g(-1) in SSP, 1.4-4.4 mu g g(-1) in PM, and 4.5-7.8 mu g g(-1) in RP+PM compared to their sole application without PSBs. The available P from inorganic SSP declined continuously from the mineral pool (after day 30) and at the end 40% of applied P was unaccounted for. However, P losses were reduced to 28 and 27% when PSBs (PSB1 and PSB3) were applied with superphosphate treatments. In the absence of PSBs, the recoveries of applied P (in soil) from RP, SSP, PM and RP+PM were 4, 25, 9, and 12%, respectively, those had been increased to 14, 30, 12 and 15% in the presence of PSBs. Similarly, the plant biomass in RP+PSBs treatments compared to the RP without PSBs increased between 12-30% in first sampling (30 DAG) and 13-30% in the second sampling (60 DAG). The P utilization efficiency (PUE) in plants supplement