Abstract: Soil phosphatases play a major role in the mineralization processes of organic phosphorus. The activity of soil phosphatases can be influenced by numerous factors and soil physico-chemical properties play a key role among them. Our research adds to the growing knowledge on soil acid (ACPA), neutral (NEPA) and alkaline phosphatase with some soil properties and total P (Ptotal), organic P (Porg), bioavailable P and inorganic phosphorus (Pinorg) fractions such as soluble and loosely bound phosphorus (Psoluble), aluminum phosphates (Al-P), iron phosphates (Fe-P), reductant soluble phosphorus (Preductant) calcium phosphates (Ca-P) and strongly adsorbed Fe and Al phosphates (Fixed-P) fractions in agricultural soils of Çarşamba Plain, Turkey. ALPA, 24.6-138.6 μg phenol g-1 3 h-1, was significantly higher than NEPA, 11.5-84.1 μg phenol g-1 3 h-1 and ACPA, 8.6 - 64.1 μg phenol g-1 3 h-1, in the studied soils. Ptotal contents in the soils ranged from 400.8 - 745.0 μg P g-1 with an average 570 μg P g-1. Phosphorus was mostly concentrated in the Pinorg (57%) although it was also present in Porg (12%) and Presidual (31%). On the average, percent of Pinorg associated with different fractions in these soils was in the decreasing order of: Ca-P > Fixed-P > Preductant > Al-P > Fe-P > Psoluble. On the basis of results obtained in this study, phosphatase activies showed significant correlations with the Ptotal, Porg, bioavailable P and some Pinorg fractions (Ca-P and Psoluble). These results suggested that Ca-P is major Pinorg compound on the effects of soil phosphatase activity in agricultural soils of Çarşamba Plain, Turkey.