Potassic fertiliser containing maximum quantity of potash is

Potassic fertilizer containing the maximum quantity of potash is a Muriate of potash.
Muriate of potash (potassium chloride). It usually contains 60% K₂O. It is the most common source of potash for farm use and is also the main potash ingredient for compound fertilizers containing potassium.
Potash is essential for plant growth and quality. It plays a vital role in the production of proteins and sugars.