Potash comes from underground deposits of ancient evaporated seas, mined primarily in Canada, Russia, and Belarus. These three countries account for roughly two-thirds of the world’s supply. The name itself traces back to an older, simpler source: wood ash boiled in iron pots, a process that produced a crude potassium-rich residite. The Dutch called it “potaschen,” and the name stuck long after the method became obsolete.
How Ancient Seas Became Underground Ore
Hundreds of millions of years ago, shallow inland seas covered large parts of what are now Canada, Germany, Russia, and Belarus. As these seas evaporated over geological time, the dissolved minerals concentrated and crystallized into thick beds of salt. Potassium-bearing minerals like sylvite settled alongside ordinary table salt (halite), forming a mixed ore called sylvinite. Tectonic shifts eventually buried these salt beds under hundreds or thousands of feet of rock, where they sit today as some of the richest mineral deposits on Earth.
Canada holds the largest known reserves at roughly 1.1 billion metric tons (measured in potassium oxide equivalent), followed by Belarus at 750 million and Russia at 650 million. The global total exceeds 3.6 billion metric tons. Israel and Jordan tap a different kind of source: the Dead Sea, which contains nearly 2 billion tons of potassium chloride dissolved in its water.
The Original Source: Wood Ash in Pots
Before industrial mining, potash was literally made in pots. Old beech trunks were burned, and the resulting ashes were kneaded into a paste with water, then smeared onto fir or pine sticks and burned again. This second round of ash was dissolved in water to create a lye, which was heated in a pot until only a dark alkaline residite remained. That residite was potash. People also burned weeds, ferns, algae, and agricultural waste to produce it. This method supplied potash for soap-making and glass production for centuries before mined potassium ores replaced it entirely.
Where Potash Is Produced Today
Global potash production in 2024 reached an estimated 48 million metric tons. Canada dominated with 15 million metric tons, more than 31% of the world total. Russia produced about 9 million, Belarus about 7 million, and China roughly 6.3 million. Together, these four countries supplied over 77% of the planet’s potash.
Canada’s production is concentrated in Saskatchewan, where the Prairie Evaporite formation holds some of the thickest and most accessible potash beds anywhere. Russia’s major deposits sit in the Ural Mountains region, particularly the Verkhnekamskoe deposit. Belarus mines the Starobinskoe deposit. China extracts potash from both conventional mines and salt lake brines in Qinghai province. Smaller producers include Germany, Spain, Laos, Chile, and the United States, which holds reserves of about 220 million metric tons, mostly in New Mexico and Utah.
Two Ways to Get It Out of the Ground
Potash is extracted through either conventional underground mining or solution mining, and the choice depends largely on how deep the deposit sits and how thick the ore bed is.
Underground Mining
Most potash mines use a “room and pillar” method. Shafts are sunk to the ore body, typically at depths under about 1,740 feet (530 meters). Machines cut into the ore, carving out large rooms while leaving pillars of uncut rock to support the ceiling. The broken ore is hauled to the surface for processing. This method works well for thinner seams, even those less than 6 feet thick, where other approaches would be impractical.
Solution Mining
For deeper deposits, generally beyond 3,000 feet (910 meters), companies inject heated water into the ore zone. The water dissolves the potassium salts, creating a concentrated brine that is pumped back to the surface. That brine is then channeled into large evaporation ponds where the water dissipates and potash crystals form. The injected water needs to be heated because warmer water can dissolve significantly more salt. Solution mining requires ore beds at least 10 feet (3 meters) thick to be viable, and it only works for certain mineral types. Some potash minerals are surrounded by even more soluble salts, which means the water would dissolve the wrong material before reaching the potash.
Turning Raw Ore Into Fertilizer
Raw potash ore is a mixture of the potassium mineral sylvite and ordinary salt (halite), along with clay and other impurities. Separating the two salts is the central challenge of potash processing, and the most common method is flotation.
In flotation, crushed ore is mixed into a brine that is already saturated with both salts so neither dissolves further. A chemical collector, heated to around 70 to 90°C so it melts into a liquid, is added to the mixture. This collector attaches selectively to sylvite crystals but not to halite, because the two minerals interact differently with water at their surfaces. When air is bubbled through the mixture, the collector-coated sylvite particles cling to the rising bubbles and float to the top, where they are skimmed off. The halite sinks and is removed as waste. The recovered sylvite is dried and sized into the granular product sold as muriate of potash, which contains 60 to 62% potassium oxide. A second common product, sulfate of potash, contains about 50% potassium oxide and is preferred for crops sensitive to chloride.
Why Potash Matters for Food Production
Potassium is one of the three essential nutrients plants need in large quantities, alongside nitrogen and phosphorus. It regulates water movement within plant cells, strengthens stems and roots, and helps plants resist disease and drought. Without adequate potassium, crops produce lower yields and poorer-quality harvests. Nearly all mined potash ends up as fertilizer, making it a critical link in the global food supply chain. Countries without domestic deposits depend heavily on imports from Canada, Russia, and Belarus, a concentration of supply that has caused price spikes during trade disruptions and geopolitical tensions.
Environmental Costs of Extraction
Potash mining generates enormous volumes of salt waste. For every ton of usable potash, significant quantities of halite and brine are left over. Managing this waste is the industry’s biggest environmental challenge. Common disposal methods include stacking solid tailings into large surface piles, storing liquid waste in lined slurry ponds, injecting brine into deep underground wells, and backfilling mined-out chambers with waste material.
The most persistent problem is salinization. Salt from tailings piles and slurry ponds can leach into groundwater and nearby rivers, altering the chemistry of freshwater ecosystems and degrading surrounding landscapes. This has been documented at major deposits in Russia, Belarus, France, and Germany. Atmospheric salt dust from mine shafts also settles on nearby land, contributing to soil contamination.
Ground subsidence is another serious risk. Because potash salts dissolve easily in water, any groundwater that seeps into mine workings can destabilize the rock above. At the Berezniki mine in Russia, flooding of an underground potash mine led to five sinkholes forming at the surface, threatening buildings and infrastructure in the city above. Backfilling mined chambers with waste material is considered the most effective countermeasure, as it supports the underground structure, reduces surface settling, and keeps waste out of surface storage. Newer operations increasingly use high-density polyethylene liners under tailings ponds to prevent brine from reaching groundwater.