Missouri’s farmers rely on a mineral that can only be found a mile deep in the earth’s crust. Its red-and-white crystals are rough to the touch and usually hidden in clay.
It’s called potash. Once refined, it becomes a powerful fertilizer that farmers use in their fields. However, its leading producer is Canada, a country that’s in the crosshairs of tariffs threatened by the White House.
On April 2, President Donald Trump announced a series of tariffs including a 10% levy on Canadian potash not compliant with rules in the United States-Mexico-Canada Agreement ensuring goods are sourced and produced in North America. USMCA-compliant potash is exempt from the tariff.
Most domestic potash production comes from three mines operated by two companies in New Mexico, according to the U.S. Geological Survey.
Ben Brown, an agricultural economist with the University of Missouri, said potash’s tariff exemption signaled just how hard it is to get domestically.
“Canada is, by far and away, a predominant source of potash, because they have those mineral reserves within their country,” Brown said. “All that does is reduce the dependence of U.S. producers using that product because it makes it more expensive, and so, in some ways, you could actually threaten food security."
The importance of potash
So what makes potash vital to America’s farms? It all has to do with nutrients found in soil.
Three nutrients are most important for healthy yields: nitrogen, phosphate and potassium. These are found naturally in the earth, but once crops are harvested these nutrients are lost in the soil and need to be replenished.
Wayne Flanary, an agronomist with University of Missouri Extension, said potash is essential for row crops and forages like corn, soy and alfalfa. Potash helps grow the stalks, leaves and even the cob in corn crops.
“There's a lot of potassium or potash that's removed whenever we harvest our forage crops, and so if we keep removing that and don't supply it back into the soil, we can reduce our yields,” Flanary said. “That's why this nutrient is important for the American farmer.”
Besides growth, potash also helps with disease prevention and water retention, making it useful for drought resistance in fields.
A big expense
March prices clocked potash at $447 per ton. That was 12% lower than in March 2024, per agriculture outlet DTN.
It is a necessary expense for producers like Kagay Farms in northwest Missouri.
Bryant Kagay is a co-owner of the farm, which produces crops like corn and soybeans. He said potash makes up around a tenth of his total expenses.
“I think the general public probably doesn't have a grasp for the number of tons of product that we require,” Kagay said. “When it comes to potash, I'm buying six or seven semi trailer loads a year. You know, it comes out to, like, 125-150 tons.”
Kagay usually buys potash around August, which means it is too early this year for him to predict how the cost might change. However, Kagay said he felt at the mercy of tariffs to conduct his business, especially because getting a domestic potash mine up and running could take too long for him to see any sort of price relief.
Still, Kagay said he isn’t necessarily against implementing tariffs on other countries if it helps local producers reach a fair price. He just wishes these measures were implemented more strategically against countries he says are in competition with the U.S., not countries like Canada.
“That's our neighbor, trading partner. I don't see why we may need to push a little bit harder with them,” Kagay said. “I just think the best way to get to a fair price is open markets.”
While most Canadian potash is exempt from American tariffs for now, there are still other factors that could affect its price. They are linked to trade movements coming out of the White House.
Brown with the University of Missouri said that because the U.S. imports potash from Canada, its price is dependent on oil prices for transportation.
“So you could imagine a scenario where, even if fertilizer prices increase, given the reductions that we've seen in oil, that lowers the transportation costs for moving the product, and actually ends up being a net zero for producers,” Brown said.
If these prices affect the cost of fertilizers like potash, Brown said this could alter how much of it farmers use in their crops. That could, in turn, impact their long-term yields. However, this would not be evident in this year’s harvest, as most farmers have already planted their crops.
“If these were to go in place and stay in place, we would expect over a growing season or two, there might be some changes,” Brown said.
As of now, tariff policy uncertainty makes predicting the price of this essential nutrient a mystery. Kagay, though, hopes potash remains largely unscathed.
“We need too many tons of it in this country,” Kagay said. “There's some in storage, but we go through what's stored locally pretty quickly.
"There's no alternative, and we need a lot of it no matter what the capacity and source ends up being.”
