Potassium (K) fertilizer is commonly added to improve the yield and quality of plants growing in soils that are lacking an adequate supply of this essential nutrient. The word “potash” is a general term that most frequently refers to potassium chloride (KCl), but it also applies to all other K-containing fertilizers, such as potassium sulfate (K2SO4, commonly referred to as sulfate of potash, or SOP).
Potassium sulfate is an excellent source of K nutrition for plants. The K portion of he K2SO4 is no different from other common potash fertilizers. However, it also supplies a valuable source of S, which protein synthesis and enzyme function require. Like K, S can also be too deficient for adequate plant growth. Further, Cl- additions should be avoided in certain soils and crops. In such cases, K2SO4 makes a very suitable K source.