Muriate of potash
Potassium chloride or muriate of potash is the most widely used potassium fertilizer. It is a white or red, crystalline salt containing 60 per cent potassium as potassium dioxide (K2O).
Muriate of potash is completely soluble in water and therefore readily available to the crops. It is not lost from the soil, as it is adsorbed on the colloidal surfaces. It can be applied basally at sowing time and after sowing in different splits.
Muriate of potash contains chlorine to about 47 per cent. The chloride content of can also be beneficial where soil chloride is low. Recent research has shown that chloride improves yield by increasing disease resistance in crops. It is not recommended to crops like tobacco, potato, etc which are sensitive to chlorine injury.
Sulphate of potash
Potassium sulphate or sulphate of potash is a white salt that contains 50 per cent potassium. It also contains around 18 per cent sulphur.
It is soluble in water and therefore readily available to the crop. It does not produce any acidity or alkalinity in the soil.
Potassium sulfate is used in crops that are sensitive to chloride or fertiliser burn like tobacco, pineapple or avocado, and in sulfur deficient soils.
It is costier than murate of potash.
Potassium Magnesium Sulfate
Potassium magnesium sulphate contains three nutrients. Potassium (K2O): 23 per cent, Magnesium (MgO): 11 per cent and Sulphur: 22 per cent.
It is used mainly for high value crops, where all three of these nutrients are required. It is also included in many ‘complete’ fertiliser products since it supplies several nutrients. Though 99.7 per cent of potassium is in water soluble form, the rate of solubility is too slow for application through fertigation systems.