Potassium sulfate, Potassium sulfate (referred to as Sulfate of Potash or SOP) is used in crops that are sensitive to chloride or fertiliser burn like , pineapple or avocado, or where sulfur is deficient.00:00:50 is a water-soluble Potassium Sulphate (SOP) fertilizer which is totally water soluble in crystalline form. It contains high quality macro and essential nutrients and chloride free ingredients. This can be applied to the crop by fertigation or through foliar spraying.