VINTON, IOWA — Iowa farmers are confronting sharp increases in fertilizer and diesel costs following Iran's closure of the Strait of Hormuz, a narrow waterway off Iran's southern coast, after the United States and Israel attacked Iran on Feb. 28, 2026. The closure has driven up global prices for fertilizer and diesel fuel, which powers most heavy agricultural equipment in the U.S.

Before the war, roughly one-third of the world's fertilizer ingredients and about one-fifth of the world's oil supplies passed daily through the strait. Since Feb. 28, the Iranian government has effectively closed the waterway, leaving many tankers stranded and disrupting supply chains that American farmers depend on.

"I am more concerned now than I have been in my 30 years of farming," said Mark Mueller, a fourth-generation Iowa farmer and president of the Iowa Corn Growers Association.

According to Mueller, his fertilizer supplier sold nitrogen fertilizer for $795 per ton on Feb. 22, 2026. By the end of March, the price had risen to $990 per ton. He purchased most of his spring fertilizer before the war but bought some at the higher prices afterward. He is now delaying purchases of additional fertilizer for summer, hoping prices will fall.

Diesel fuel has also risen. The nationwide average stood at $3.76 per gallon right before the war and has since climbed to $5.51 per gallon, according to AAA.

The cost pressures arrived at a time when many farmers were already under financial strain. According to Mueller, consolidation in the fertilizer industry and increased competition from abroad had resulted in higher prices for fertilizer and feed, producing smaller returns on his corn and soybean crops. Many farmers who could not pay their bills in recent years went out of business, he said. In 2025, the number of Chapter 12 farm bankruptcies reached 315, a 46% increase from the previous year, according to the American Farm Bureau Federation.

President Donald Trump's tariffs added to the cost of goods imported by farmers from overseas and frustrated many foreign buyers of U.S. agricultural products. "Our government made our life more difficult by walking away from trade deals or instituting tariffs or just basically making our customers angry — our customers being other nations and companies in other nations," Mueller said.

Lance Lillibridge, a corn and cattle farmer in Vinton, Iowa, said the rising input costs could cut into his production. "I'm probably going to see a reduction in yield," Lillibridge said.