Kainit

An inorganic source of potassium, which is or was sometimes used within a fertiliser compound. The material typically contains 20% potassium chloride, 15% magnesium sulphate and 46% sodium chloride; It contains 12% potassium (14% potash). If it formed part of a compound fertiliser applied as a seed bed fertiliser then in the past it would have been applied in the autumn or early winter to the soil to allow the undesirable concentration of salts to be washed through the soil in anticipation of a spring sowing: This is not a viable practice in modern turf care.