Phosphorus is one of the least available mineral nutrients to the plants in many cropping environments. Sub-optimal P nutrition can lead to yield losses in the range of 10% to 15% of the maximal yields. P deficiency is more critical in highly withered soils as well as in calcareous and alkaline soils. Amelioration attempts by addition of phosphatic fertilizers are economically and ecologically unsound as the efficiency of added phosphatic fertilizers is very low. Inoculation with the mineral phosphate solubilizing microbes would be reliable due to consistent performance of the inoculants under field conditions, their use also induces resistance against salinity and pathogens. Phosphorus fixation predominates in both acidic and alkaline soils, resulting in its low efficiency. Use of phosphate solubilizing microorganisms play vital role in solubilizing the insoluble forms of phosphorus. Strains from genera Pseudomonas, Bacillus, Rhizobium, Aspergillus and Cephalosporium are among the phosphate solubilizers. Principal mechanism for mineral phosphate solubilization involves production of organic acids, and acid phosphatases play major role in mineralization of organic phosphorous in soil. The present study highlights various forms of soil-phosphorus, phosphorus-fixation mechanism in acidic and alkaline soils and role of Phosphate solubilizing microorganisms in solubilization of fixed-phosphorus in relation to crop responses.