When discussing phosphorus and potassium products, many growers first think of monopotassium phosphate (MKP). Another product with a similar name - monopotassium phosphite (MKPI) - is also attracting attention. MKP is commonly labelled 0-52-34, while MKPI is often marketed as 0-58-38. These figures may suggest that MKPI contains “more phosphorus and potassium,” but nutrient percentages alone do not explain how the two products work. The key is to distinguish phosphite from ph