By Lisa Baertlein and Karl Plume

LOS ANGELES/CHICAGO, June 18 (Reuters) - U.S. imports of fertilizers from Middle Eastern ports affected by the Strait of Hormuz closure fell to zero in May, contributing to a 44% year-on-year drop in overall crop nutrient imports, trade data provider Descartes Datamyne said on Thursday, in one of the first estimates of the Iran war's impact on U.S. farmers.

The Middle East is a leading fertilizer production hub, and nearly one-third of the global fertilizer trade typically passes through the Strait of Hormuz, which has seen traffic brought to a standstill since the U.S. and Israel attacked Iran in late February. Supplies of urea - a nitrogen-based fertilizer - from the world's largest production facility in Qatar have been halted, and flows of sulfur and ammonia, common inputs for a range of fertilizers, have also been curbed.

The resulting fertilizer supply crunch sent prices soaring on fears of shortages. That has intensified strains on U.S. farmers - one of President Donald Trump's key voting blocs - and caused global relief organizations to warn it could exacerbate hunger in vulnerable nations by endangering next year's grain harvests.

U.S. imports of fertilizers from Hormuz-affected ports fell from 93,550 metric tons in May 2025 to nothing in May this year. At the same time, total U.S. fertilizer imports fell from 991,322 metric tons to 552,767 metric tons, Descartes Datamyne said.

Global fertilizer prices jumped by about 20% between February and May, according to the United Nations' Food and Agriculture Organization, as the Middle Eastern Gulf had provided 34% of the world's urea fertilizer, 23% of world ammonia exports, and nearly half of sulfur exports. Prices of nitrogen fertilizers have eased more recently due to a seasonal demand dip, while phosphate prices remain elevated.

U.S. fertilizer imports typically rise early in the calendar year as suppliers build inventories ahead of spring planting. February 2026 imports had reached 464,253 metric tons before tumbling in each of the next three months, Descartes Datamyne data showed.

U.S. farmers, who grow crops such as corn, wheat, soybeans and sorghum, have been stung by higher fertilizer and fuel costs, adding to pressure from drought, rising input costs and lost sales due to Trump's tariff policies.

Elevated fertilizer prices could last into 2027 regardless of how soon the Iran war ends, Ken Seitz, president of Nutrien NTR.TO, the world's biggest potash producer, said in May.

The U.S. Federal Trade Commission late last month announced an investigation into fertilizer prices, which spiked after the start of ​the U.S.-Israeli war on Iran.

Trump last week said ​he is ​considering taking action ⁠to ​help farmers affected ​by high fertilizer prices without providing details.