Potash is a generic term that refers to a group of potassium-bearing minerals, naturally occurring potassium salts and the products produced from those salts.Potash is a plant's main source of potassium. Potassium ('K') is one of the four primary nutrients required for plant growth. The remaining three nutrients are Nitrogen ('N'), Phosphate ('P') and Sulphur ('S'). Potash is used in fertilizers and applied through the soil for uptake by plant roots. more... See more text