This study aims to test the effectiveness of Gafsa phosphate rock (GPR) use as phosphate fertilizer compared to water soluble fertilizer as triple super phosphate (TSP). An experiment was carried out to evaluate different soil chemical properties that control P solubility and mobility from GPR using the 32P isotopic kinetic method. Seven soils with different soil pH were mixed with GPR and TSP at three rates (0, 500, 2000 mg P/kg) corresponding to localized P fertilization usually applied in orchard. The treatments were replicated three times and incubated for one month in moist conditions. Changes in the amount of isotopically exchangeable P (E) and the amount of P transferred from the solid constituents to the soil solution after different periods (Pr) as well as changes in pH, Ca and P concentrations in soils suspensions were determined. The relative efficiency of the GPR to water soluble fertilizer in the seven soils was with an increase in soil acidity. For each soil, the relative efficiency varied differently for the two P applications rates of GPR. In fact, it was noticed that in two soils with different pH (5.5 and 6.2), the relative efficiency decreased with the high P rate of GPR. This result may be explained by a liming effect of GPR resulting in a high increase of pH and the calcium concentration in these soils limits the GPR dissolution and reduces mobility of soluble P in soil solution. These results contrast with the one obtained for a soil with pH (6.5) because of its high pH buffering capacity. Our results demonstrate the importance of considering the soil properties to evaluate the GPR efficiency and manage GPR fertilization.Read less <