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

Abstract

Abstract‘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°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 µg g−1 in RP, 5.0–9.9 µg g−1 in SSP, 1.4–4.4 µg g−1 in PM, and 4.5–7.8 µg 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 supplemented with PSBs was 20–73% higher compared to those without PSBs. The detection of oxalic and gluconic acids in culture medium treated with PSBs (7.8–25.0 and 25–90 mg L−1, respectively) confirmed the production of organic acids by the indigenous bacterial isolates. This study indicate that low P recovery both in plant and soil can likely be improved by using indigenous PSBs and organic amendment poultry manure, which allowed a more efficient capture of P released due to P solubilization.