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

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Potash was originally made by leaching tree ashes in metal pots.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

MOP is the most common potash, representing approximately 95% of agricultural potash worldwide, but there are several other forms. The second major form of potash is potassium sulphate or Sulphate of Potash (SOP). What’s the difference? MOP is about half potassium, half chloride, which makes it useful in applications where soil chloride content is low. It is used on carbohydrate crops including wheat, oats, and barley. Also, it’s cost-effective compared to other potassium compounds.

Unlike MOP, which is mined, most SOP is produced chemically. SOP doesn’t contain any chloride, which can be an advantage in situations where soil chloride content is high, for example, in very dry environments. SOP is considered a specialty fertilizer for crops such as fruits, vegetables, potatoes, tobacco, and tree nuts and though it represents a smaller market than MOP, it is priced at a premium.

Where does potash come from?

Most of the world’s potash comes from Canada, with the largest deposits located in Saskatchewan and New Brunswick. Russia and Belarus rank as the second and third highest potash producers. In the United States, 85% of potash is imported from Canada, with the remaining produced in Michigan, New Mexico, and Utah. According to the U.S. Geological Survey, the 2013 production value of marketable potash, f.o.b. mine, was about $649 million. The fertilizer industry used about 85% of U.S. potash sales, and the chemical industry used the remainder. More than 60% of the potash produced was MOP.

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, bulk weighing and monitoring products and mineral analyzers and sampling systems.