Abstract: The invention relates to a process for producing a controlled release fertilizer of potassium chloride comprising the following steps: a. providing compacted KCl, having a sphericity of below 0.87; b. dry polishing the KCl in an intensive mixer type device consisting of a container vessel and at least one set of agitating elements such that the KCl has a sphericity of between 0.88 and 0.92; c. providing a coating on said polished KCl. The polished and coated compacted KCl can show with 6 pph coating a release of about 18% after 7 days measured with a water leach test at 21 C. The polished and coated compacted KCl may have one or more of the following release properties: a release at 10 days of about 20% or less; and/or a release at 30 days of 40% or less; and/or a release at 50 days of 50% or less.