Principal K fertilizer materials commercially available. Potassium chloride is produced in four major size grades. They include, in order of increasing fineness, granular, coarse, standard, and soluble. Granular and coarse grades cost somewhat more to produce than standard. They are more suitable for use in dry bulk blends with nitrogen and phosphate fertilizers because they reduce segregation during mixing and shipment to the farm.
Soluble white is used in fertilizer solutions.
Crop responses to these K fertilizers have shown no agronomic differences provided the same amount of K is applied and the same placement compared. Reaction of these materials in soils are identical. Potassium content of manures varies greatly depending on animal type, feed ration, storage, and handling. Since much of the K in manure is soluble, it can be lost by leaching from open lot manure collection systems. Depending on water content, manure may supply 5-50 lb. of K per ton.