Such research was conducted aiming to evaluate soil fertility of 43 locations in Sharkia Governorate, Egypt through determination available and exchangeable K and their relationships with K potential. Main physical and chemical properties, as well aswater soluble K, available K, exchangeable K, potassium potential, the potential buffering capacity and the activity ratio of potassium were determined. Sand content ranged from 14.0 to 95.6%. Clay content ranged from 2.4 to 61.9%. Calcium carbonate ranged from 1.14 to 64.76 g kg^-1 and organic matter ranged from 2.69 to 22.83 g kg^-1. Soluble potassium ranged from 5.60 to 89.06 mg kg^-1. The highest was in Ezbet Elgendy which is characterized with high salinity and the lowest was in Ezbet Abd-Elraaof soil. Exchangeable K ranged between 29.28 and 636.31 mg/ kg^-1, the highest was in Elfaddadna soil and the lowest was in Abd-Elraaof soil.  Available K ranged from 34.88 to 678.4 mg kg^-1 soil. Potassium potential ranged between 2.10 to 2.63. High values were in soils characterized with light texture such those of Geta and Elmahawda. Low values were in soils of Ezbet Abd-Elraaof. Most of the soils have fairly adequate potassium content.