Azospirillum species were collected from the rhizosphere and free soil of different plants in Al-Jabal El-Akhdar region. The isolates were identified according to biochemical activities. Isolate (H3) which showed the higher solubilization efficiency (SE) on Pikovskaya medium (PVK) containing insoluble phosphate (inorganic phosphate) Ca3(po4)2 Isolate (H3) was identified as Azospirillum lipoferum (H3), which used as an inoculum as free cell suspension or as alginate formulation. Phosphate solubilization was measured by A.lipoferum (H3) as free or alginate immobilized cells in (PVK) liquid medium and recording the pH of the medium at the same time. The results showed in the phosphorus content by immobilized bacteria in liquid (PVK) broth medium from 2 nd day of incubation (2.48 µg/ ml) to 10 th day (3.70 µg/ ml) and the free bacteria from 2 nd day (8.81 µg/ ml) to 10 th day (4.49 µg/ ml). pH of the liquid (PVK) broth medium was recorded from 2 nd day to 10 th day after incubation which decreased by immobilized A.lipoferum (H3) from 7.00 pH to 4.47 on the 10 th day and by the free A.lipoferum (H3) to 6.00, which improved the production of organic acids from sugars which was response of decreasing the pH of the medium. This present study contribute to make agriculture more productive with less harm to the environment and for developing countries where the use of fertilizers is costly, and to encourage of using the biofertilizers 'plant growth promoting rhizobacteria' (PGPR) instead of the chemical fertilizers to enhance the plant growth which is the main goal to increase the food production in a healthy way.