Why the US-Canada trade war could change how American farmers grow their crops for years
Most healthy soybean fields like this one in Minnesota rely on fertilizer. Richard Hamilton Smith/Design Pics Editorial/Universal Images Group via Getty Images U.S.
In August 2026, the United States and Canada, longtime allies, entered a trade war after trade talks failed. On August 15, 2026, the U.S. imposed 50% tariffs on Canadian imports worth about US$20 billion (CAD$27 billion). Canada responded on August 25, 2026, by announcing retaliatory tariffs of 15% to 50% on the same value of U.S. goods, effective September 8, 2026. These tariffs are taxes on imported goods paid by the importer, which increases the cost of those goods. For example, if a U.S. farmer buys a tractor from Canada, the tariff raises the price they pay. The tariffs are not directly aimed at farmers but will affect them indirectly by increasing costs for agricultural equipment and other goods.
Canada’s retaliatory tariffs target a range of U.S. goods, including dairy products, agricultural equipment, and potentially a crucial fertilizer ingredient called potash. Potash is a mineral used to produce potassium, one of the three main nutrients (along with nitrogen and phosphorus) that crops need to grow. The tariffs aim to match the U.S. tariffs dollar for dollar. Canada is one of the largest markets for American food, importing about $28 billion in U.S. agricultural products in 2025. Both countries are deeply integrated in agricultural trade, with farm equipment, live cattle, and processed foods moving across the border. The tariffs could disrupt these supply chains, raising costs for farmers and consumers alike.
The U.S. relies heavily on Canada for potash, a key ingredient in fertilizer. American mines produce less than 1% of the global potash supply, and the U.S. imports more than 80% of its potassium from the Elk Point Basin in Saskatchewan, Canada. Crops require three main nutrients: nitrogen, phosphorus, and potassium. Potassium, sourced almost entirely from potash, is essential for plant health. If Canada imposes export tariffs on potash or restricts its supply, the price of fertilizer for U.S. farmers could rise sharply. This would force farmers to reduce their use of potash, which builds up in the soil over time but takes years to restore if depleted.
American farmers are already struggling with high fertilizer costs due to disruptions in global supply chains. A war between the U.S. and Iran shut down shipping through the Strait of Hormuz, cutting off a major source of nitrogen fertilizer. A Farm Bureau survey in April 2026 found that 70% of farmers said they couldn’t afford all the fertilizer they needed during spring planting. Fertilizer prices are expected to rise further if Canada imposes tariffs on potash. Farmers may cut back on phosphorus and potassium first, as these nutrients can be stored in the soil, but nitrogen must be reapplied every year. This could lead to smaller harvests in the future.
Trade policy uncertainty can affect farmers’ decisions even before tariffs take effect. If farmers are unsure about future fertilizer prices or availability, they may delay purchasing fertilizer until prices stabilize. Fertilizer is often bought months ahead of planting, so hesitation in the fall can mean less is applied in the spring. This uncertainty alone can reduce the amount of fertilizer used, even if no tariffs are imposed. The effects of reduced fertilizer use may not be immediately visible but could lead to smaller crop yields in the future, ultimately driving up food prices for consumers.
If the trade war continues, the impact on U.S. agriculture could extend beyond a single bad season. Farmers may need to reduce their use of potash due to high prices or limited supply. Potassium builds up in the soil, but restoring it takes time—several pounds of fertilizer are needed for every pound of soil-test potassium recovered, spread over years. Even a one-year restriction on potash access could have lasting effects on soil health and crop yields. Over time, this could lead to smaller harvests and higher food prices, even after the tariffs are lifted. The long-term consequences of the trade war could reshape how American farmers grow their crops for years to come.
