Potash: A Look at the World’s Most Popular Fertilizer

Uses, Types, Production, and USGS Data

Potash, pronounced pot-ash, is the term commonly used to describe potassium-containing salts used as fertilizer. Most potash is derived from potassium chloride (KCl), which is also known as Muriate of Potash (MOP).  As a source of soluble potassium, potash is vital to the agricultural industry as a primary plant nutrient. Potash increases water retention in plants, improves crop yields, and influences the taste, texture, and nutritional value of many plants.

Potash was originally made by leaching tree ashes in metal pots. The process left a white residue on the pot, called “pot ash.”

MOP vs. SOP

Muriate of Potash (MOP)

MOP is potassium chloride and remains the most widely used potash fertilizer globally. USGS defines MOP as an agriculturally acceptable mix of KCl that is 95% pure or greater, with sodium chloride for fertilizer use.

Sulfate of Potash (SOP)

SOP is potassium sulfate. It is commonly used where chloride-sensitive crops or soil conditions make sulfate-based potassium sources more suitable. USGS includes SOP as one of the principal potassic fertilizers used in agriculture.

Sulfate of Potash Magnesia (SOPM)

SOPM, also called langbeinite, is another recognized potassic fertilizer named by USGS. In the United States, more than 60% of potash produced in 2025 was SOPM and SOP, largely because these products are needed for certain chloride-sensitive crops.

Where Does Potash Come From?

According to the USGS, Potash is produced from both conventional mining and brine-based operations. In the United States, most production in 2025 came from southeastern New Mexico, where two companies operated two underground mines and one deep-well solution mine. Utah also had three active potash facilities, including operations using solar evaporation and flotation to produce MOP and SOP.

USGS also reports large domestic resources beyond currently active operations. Estimated U.S. potash resources total about 7 billion tons, with major resources in Montana and North Dakota, plus significant resources in Utah, Arizona, and Michigan.

Potash Mining

Today, potash comes from either underground or solution mining. Underground potash deposits come from evaporated sea beds. Boring machines dig out the ore, which is transported to the surface to the processing mill, where the raw ore is crushed and refined to extract the potassium salts. When deposits are located very deep in the earth, solution mining is used as an alternative to traditional underground mining. Solution mining employs the use of water or brine to dissolve water soluble minerals such as potash, magnesium  or other salts. Wells are drilled down to the salt deposits, and the solvent is injected into the ore body to dissolve it. The solution is then pumped to surface and the minerals are recovered through recrystallization.

What both mining techniques have in common is that companies employing either one need to improve operational efficiency and quality control, increase productivity, manage data, and monitor their operations for compliance with product and environmental safety standards. Laboratory information management systems (LIMS) are the ideal solution to accomplish these goals. Other solutions that improve mine operational efficiency include portable x-ray fluorescence (XRF) analyzers.

Handheld X-ray fluorescence (XRF) analyzers facilitate and provide rapid, non-destructive elemental analysis of geological samples, which are especially helpful during mineral exploration. These portable devices enable immediate, on-site analysis, supporting quick decision-making and more efficient exploration activities. By delivering accurate elemental composition data, portable XRF technology enhances the speed and precision of geological surveys, making it an indispensable tool for prospecting, exploration, and optimizing mining operations. XRF analyzers can detect Potassium (K) and Chlorine (Cl) — the most important component for potash.

Editor’s Note:

This article was originally published 06.26.2014 with the byline Ali Somarin, but has been updated with the latest USGS information, refreshed, and broken links fixed by the editor.

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