Enhancement of Fertilizer Value of Phosphate Rocks by Phosphate Solubilizing Microbes

Abstract

To enhance the fertilizer value of rock phosphate in alkaline soils, the phosphate (P) solubilizing microorganisms (PSMs) were isolated from the rhizosphere soil of Jatropha curcas growing in the landfills of rock phosphate mines of Rajasthan State Mines and Minerals Limited (RSMML), Jhamarkotra, Udaipur, India. These microorganisms were tested for their efficacy to solubilize rock phosphate (RP) and different metal phosphates. These PSMs were also tested for promotion of the growth of wheat and maize plants grown in soil amended with RP. The results showed that P solubilizing microorganisms effectively solubilized different unavailable phosphates in Pikovskaya’s medium and released higher amount of phosphorus. The solubilization changes in response to the change in nutrients. Field experiments showed that inoculation of PSMs significantly increased the growth and yield of two consecutive crops i.e. wheat and maize compared to the control soil. It was found that crop productivity can be enhanced by using cheaply available RP as a fertilizer along with P solubilizing microorganisms in alkaline soils. These phosphate solubilizing microbes can survive in the soil system to retain the phosphate solubilizing potential for long time and improve the soil characteristics. This may be the first report indicating the direct application of raw rock phosphate as fertilizer along with P solubilizing microorganisms in alkaline soils.