U.S. President Donald Trump’s trade war with Canada is getting personal for American farmers.
After trade talks between the two longtime allies fell apart in mid-August 2026, Trump imposed 50% tariffs on a wide range of Canadian imports worth roughly US$20 billion (CAD$27 billion). Canada responded on Aug. 25, 2026, by announcing its own plan to put retaliatory tariffs of 15% to 50% on the same value of U.S. goods, effective Sept. 8.
Canada’s list includes dairy products and agricultural equipment, and there is an unspoken threat that it could expand to a crucial component in fertilizer that U.S. farmers rely on.
I have studied agriculture and water quality for more than a decade, including whether trade rules change how farmers manage their land.
In my assessment, the enduring effect of this trade war on U.S. agriculture, if it continues to escalate, won’t be a single bad season. Across thousands of farms, farmers may have to reduce their fertilizer use as prices – already high from supply disruptions because of the war in Iran – rise. It may have little visible consequence at first, but the lasting impact could emerge later in smaller future harvests if this trade war continues.
Are Canada’s tariffs aimed at farmers?
Canada’s tariffs aren’t directly aimed at farmers, but farms will feel the cost if they go into effect.
A tariff is a tax on imported goods paid by the importer, effectively raising the cost of those goods. When China responded to U.S. tariffs during the first Trump administration in 2018, its retaliatory tariffs hit U.S. soybeans and automobiles, directly affecting the American agricultural sector. Research shows U.S. agricultural exports to China fell by $7 billion to $10 billion a year, as Chinese buyers shifted to Brazilian suppliers.
Canada’s tariff list for Sept. 8 appears to match U.S. tariffs dollar for dollar. I believe agriculture is caught in the broader fallout, not directly targeted.
However, the effect will still reach farms.
Canada is one of the largest markets for American food, importing about $28 billion in U.S. agricultural products in 2025. Both U.S. and Canada are also deeply integrated in agricultural trade and farm equipment markets. Farm equipment is assembled from parts that cross the border. Live cattle and processed foods also move both ways.
Tariffs can raise costs along that chain. Canadian officials, recognizing that, included several billion dollars in aid for their farmers in announcing the tariff plan.
An analysis of the tariffs Trump ordered in 2025 on countries around the world shows how fast agricultural trade flows reorganize under this sort of pressure. When North American trade barriers go up, U.S. imports of fruits and vegetables from Canada and Mexico typically drop, with buyers turning to Australia and Argentina instead. The result is often higher consumer prices for key agriculture products in the United States.
AP Photo/Mike Stewart
The fertilizer risk
Canada is also a major source of potash, a fertilizer ingredient that U.S. farmers depend on.
If pushed too far, Canada could levy export tariffs on potash and, potentially, even on oil, natural gas and electricity, raising the price for U.S. buyers. The widespread impact that such a move would have on U.S. consumer prices may give Canada leverage going forward.
Crops require three main nutrients: nitrogen, phosphorus and potassium. Potassium comes almost entirely from potash. 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. These are geology-based U.S. constraints in agriculture.
Notably, potash was not included in the U.S. tariff list. Taxing such a key agricultural input would have raised costs for American growers.
How trade policy changes growing decisions
American farmers are already squeezed on fertilizer costs.
When the U.S. and Israeli war with Iran shut down shipping through the Strait of Hormuz, it cut off a large source of nitrogen fertilizer, raising fertilizer and fuel prices. A Farm Bureau survey in April 2026 found 70% of farmers said they couldn’t afford all the fertilizer they needed during spring planting.
Nitrogen washes out of soil and must be reapplied every year. Potassium and phosphorus, on the other hand, build up as a reserve. This means that a farmer facing high prices can skip an application and briefly live off that reserve. This is consistent with advice from agricultural extension researchers who compare this coping strategy to a fuel gauge: You can make a trip or two without refilling, but not the third.
Potash was the one major nutrient that the Iran shock didn’t directly affect. However, if Canada raises the price of potash, that could have similar effects.
When fertilizer prices spike, farmers tend to cut phosphorus and potassium first and nitrogen last. But restoring potassium in soil takes time, with several pounds of fertilizer for every pound of soil-test potassium recovered, spread over years. So, even a one-year restriction on potash access can have an impact.
Uncertainty has an effect on farmers’ choices
Economic research shows that trade policy uncertainty affects agricultural decisions even before tariffs take effect. A farmer who cannot predict next year’s costs may delay the purchase and hope that prices will ease.
Fertilizer is often bought months ahead of planting, so hesitating in the fall can mean less goes on the ground in the spring. Uncertainty alone can reduce what gets applied before any tariff exists.
If U.S. farmers end up facing higher prices or short supplies for potassium fertilizer, the effects over time, including the chance of smaller yields, would arrive at the grocery store in the form of higher food prices long after the tariffs are likely to be lifted.
Jayash Paudel currently receives funding from the US Department of Agriculture and the National Science Foundation, and his previous research has received funding from the Institute for Humane Studies, the World Institute for Development Economics Research, and Data Institute for Societal Challenges.
