Potash fertilisers are an available source of potash for plants, and muriate of potash is the most common type. Plants cannot achieve maximum growth and yield without potassium, nor can the functions that potassium performs be carried out by other nutrients. Nearly every phase of healthy plant growth and development relies on an adequate supply of potassium. Potash fertilisers can be applied directly to the soil or mechanically or chemically blended with other nutrients.

Potash is mined from ore deep underground or extracted from brine by means of solution mining, and is milled on the surface. In its processed state, potash appears as a granular mineral of varying sizes, and ranges in colour from white to red depending on the presence of iron oxides and hydroxides and clay minerals which remain after processing.

There are two principal MOP grades: Standard/Fine and Granular/Coarse. These types of potash fertiliser differ in particle size, which is important for delivery specifications. Standard includes white muriate of potash (referred to as White MOP) and pink muriate of potash (referred to as Pink MOP).