Phosphate Forms As Affected By Different Soil Properties In Some Soils of Saudi Arabia

Eighteen calcareous soil samples were collected from different regions of Saudi Arabia to study the effect of soil properties on distribution of soil phosphorus. The contribution of different phosphorus forms to available P was determined. The simple correlation, stepwise multiple regression and partial correlation coefficient analysis was done for those parameters. Saloid-P (extractable P in 1N NH4Cl) has significant correlation with soil organic matter. Aluminium-bound P (AL-P) decreased significantly with CaCO¬3 content, while iron-bound P (Fe-P) increased with soil organic matter content. The calcium-bound P (Ca-P) represents the major fraction of inorganic P which ranged from 78.1 to 90.6%. High significant positive correlation was obtained between Ca-P fraction and CaCO3 content of soil samples. The pH and EC values were positively correlated with Ca-P. Available-P, as extracted by Olsen solution, was positively correlated with Ca-P, organic-P and Fe-P. The stepwise multiple regression analysis indicated that contribution of Ca-P, organic-P and saloid-P to available-P was 81.3%