More than 90% of Pakistani soils are phosphorus deficient (contain < 10 mg kg–1 bio–available P), even though total P in these soils varies from 175–1300 mg kg–1. Moreover, phosphates from P fertilizers soon after their application are fixed with calcium in calcareous soils. Certain bacteria as well as fungi have the potential to solubilize / release the native fixed inorganic soil P. Phosphorus solubilization by the microorganism is very important aspect in the scenario when world’s rock phosphate resource (raw material for phosphatic fertilizers) is depleting and limiting its use in fertilizer industry due to its competitiveness day by day with other industries, viz., metallurgy, explosives, ceramics, water treatment, fungicides, food preservatives, cosmetics, anti corrosion agents etc. Soil sampling on the basis of calcareousness was carried out. Two soils series, viz., Kahuta (non calcareous) and Balkasar (calcareous) were selected for the purpose of research. Experiments under incubation and greenhouse (with maize crop) environment were performed simultaneously under different doses of applied P fertilizer, viz., 0, 150, 300, 450, 600, 750 and 900 mg kg–1 of soil to study the P dynamics. The treatments were incubated at 25 °C for 90 days under incubation experiment while maize crop was sown in case of greenhouse experiment. Soil samples were taken at 30 days interval from both experiments and were analyzed for different P forms through sequential P fractionation scheme. Pattern of P fractions as affected by different P doses was studied. It was noticed that all P fractions except Olsen–P and Ca2–P were increased with the application of P fertilizer with passage of time. This increase was greater for higher P doses. The xvi increase was more in Ca– and Al– bound P forms in case of Balkasar soil series if compared with Kahuta soil. The Fe–P increase was higher in case of non calcareous Kahuta soil than in Balkasar soil series. The Ca2–P and Olsen–P was higher at 30 days which decreased with the passage of time. Increase in P fractions was more pronounced in incubation than greenhouse experiment. Plant P uptake was also influenced positively with the addition of each successive P dose till 450 mg kg–1 but remained unaffected at higher P doses. Phosphorus solubilizing bacteria / fungi (PSB/PSF) were isolated from the aforesaid soil series. These phosphate solubilizing microorganisms (PSMs) were identified through biochemical and molecular techniques and were tested for phosphorus solubilization index (PSI), pH drop, P solubilization in broth culture. The results indicated that the PSM isolated from calcareous soil were more efficient in their potential to solubilize phosphorus. The PSM isolated and identified in the previous study were further tested for their potential to transfigure the P forms in calcareous and non calcareous soils in incubation followed by greenhouse study. The results showed that Aspergillus niger among PSF and Burkholderia cepacia among PSB performed better in transforming the soil P fractions. The impact was more conspicuous in calcareous soil. The PSM although could also solubilizes the Al– and Fe– bound P but their effect on Ca– bound P fractions was more prominent. The P fractions including Ca8–P, Fe–P, Ca10–P and Al–P decreased with inoculation of PSM in comparison with control under maize crop. Olsen–P and Ca2–P increased with the inoculation, while occluded–P remained unaffected with the addition of PSM. Furthermore, impact of PSF on soil P forms and plant available P was more prominent than their PSB counterparts.