Muriate of potash

MOP is refined from mined potash ore (sylvinite) through processes such as flotation or dissolution-recrystallisation, yielding potassium chloride at a typical guaranteed analysis of about 60% K₂O.

Chemical formula

KCl

Potassium content

About 60% K₂O

Chloride content

About 45–47%, supplied alongside potassium

Source

Mined from underground evaporite (potash) deposits

MOP supplies potassium, an essential macronutrient involved in water regulation, enzyme activation, and overall plant vigour, together with chloride, a nutrient required in much smaller amounts but present in relatively high proportion in this fertilizer.

• Potassium is highly water-soluble and readily taken up by roots
• Chloride accompanies potassium in every unit applied
• No nitrogen, phosphorus, or sulfur is supplied

MOP is the dominant potassium source worldwide because of its high analysis and comparatively low cost per unit of potassium, and it is used across a broad range of field crops where chloride sensitivity is not a limiting concern.

• Lowest cost per unit of potassium among common potassium fertilizers
• High analysis reduces bulk and transport cost
• Suitable for most field crops that are not notably chloride-sensitive

General practice weighs MOP against chloride-sensitive alternatives such as sulfate of potash for crops where quality or chloride tolerance is a concern, and considers soil potassium status and cation exchange capacity, which influence how well potassium is retained against leaching.

Potassium is retained relatively well by soils with adequate cation exchange capacity, but on coarse-textured or low-exchange-capacity soils it can be more prone to leaching. Repeated heavy use of chloride-containing fertilizers can also contribute to localised soil salinity concerns in some conditions.