Surface clay Soil (0-30) was collected from EL Hamoul Kafr El-Sheikh Governorate Next to Kitchener Drainage. the soil sample was air-dried, Soil properties pH, EC, clay content. Five hundred grams of air-dried soil samples were weighted in plastic columns. Three rats of compost (0, 2,4%) and three rats rock phosphate (0,1,3%) were added. The soil samples were taken at different incubation period (0, 3, 6) months. Soil pH , EC, and organic matter (SOM) were measured. Hedley sequential fractionation scheme was used to study P fractions. The P fractions were: (1)P-NaHCO3 (2) P-NaOH (3) P- HCl/H2SO4 (4) P-residual and (5) Total P. Results revealed that a slight and insignificant decrease in pH values with increasing phosphate rock added, clearly decrease in values of soil pH by increasing the amount of compost added (%).There was a rise in values of soil EC by increasing the amount of compost (%) and the increasing in incubation time led to decreased in the soil EC values. The SOM values, were slight and insignificant increase when RP was increased from 0 to 1 % but when PR was increased to 3 % there was a significant increase in SOM values.
The increasing addition of compost led to increased P-NaHCO3 fraction comparing with control treatment, while the addition of rock phosphate led to a decrease in this fraction and gave the lowest value. The addition of compost and rock phosphate together increased P-NaHCO3 fraction more than compost alone or phosphate rock alone. Obtained results revealed that the increase in the incubation period led to an unnoticeable and insignificant decrease in this fraction of phosphorous. The results revealed that P-NaOH fraction represents 2.8 % of the total phosphorous. The results indicated that P-HCl/H2SO4 fraction increased as the incubation periods, phosphate rock and compost were increased. The obtained results showed residual P fraction was decreased with increasing incubation period.