Jeff Winton, a dairy farmer in upstate New York who grows much of the feed for his own cattle, stopped planting corn in 2022 when fertiliser prices spiked. “We just couldn’t afford the input costs,” he recalled.

The surge began after Russia’s invasion of Ukraine disrupted exports of nitrogen, urea and other key fertiliser nutrients, with Russia, alongside its ally Belarus, among the world’s leading suppliers.

As the war in Ukraine entered its fourth year, a separate conflict involving the US, Israel and Iran has disrupted the Strait of Hormuz, a critical artery of global fertiliser trade, compounding pressure on American farmers who have already been facing rising bankruptcies and sharply lower incomes despite higher government payouts.

“Back then it was tough, but this time it’s even worse,” Winton said. “Everything’s stacked against us right now – prices, labour, healthcare – and now fertiliser costs are through the roof. Farmers across the country are scared.” He lamented: “It’s literally a perfect storm.”

Before the Iran war began on February 28, the narrow gateway at the mouth of the Persian Gulf carried about one-third of global seaborne fertiliser trade and roughly half of the world’s urea, the most widely used nitrogen fertiliser. Major producers such as Qatar and Saudi Arabia depend on this route to export large volumes of fertiliser produced from cheap local natural gas.

Despite a two-week ceasefire being announced, the strait remains largely closed.