The effect of isolated phosphorus solubilizing bacteria and molasses on Soluble and available P in wheat straw medium

Phosphorus solubilizing microorganisms are capable of transforming insoluble phosphorus (P) forms to soluble and bioavailable P. The aim of the present study was to isolate P solubilizing bacteria from forest soils around the rock phosphate (RP) mine of Koh-e-SepidLar in Kohgiluyeh and Boyer Ahmad province and evaluate their ability in Sperber culture medium and wheat straw medium in the presence of RP and molasses. Bacteria were isolated and conducted by serial dilution and culturedon Pikovskaya medium. Quantitative assessment of 6 isolated bacteria carried out in the Sperber medium with tricalcium phosphate with 3 replications. Soluble P was measured on 5, 10, 15 and 20 days. The ability of two most effective bacteria in the liquid culture, assessed in wheat straw medium in a completely randomized design. Treatments consisted of a factorial combination of three RP levels (zero, 1:8 and 1:4 RP: wheat straw) and molasses in three rates (zero, 0.5 and 1% w/w) and three bacteria levels (none inoculated, and inoculated with isolates 1 and 2, separately). Soluble P and available P were measured on 20 and 40 days with CaCl2 0.01 M and NaHCO3 0.5 M, respectively. Some bacteria with P solubilizing capability found in the Pikovskaya medium. Two isolates showed the highest ability in liquid culture. CaCl2-P in the presence of isolates 1 and 2 was higher than blank in wheat straw medium. Molasses caused the increase of CaCl2-P in both times. Presence of RP reduced CaCl2-P. Highlights Isolation of P solubilizing bacteria from forest soils around the rock phosphate (RP) mine in Kohgiluyeh and Boyer Ahmad Molasses caused the increase of CaCl2-P in both time. Presence of RP reduced CaCl2-P.