More than half of the Middle East’s urea output may have been lost since the start of the Iran conflict, which is continuing to disrupt fertilizer flows from the region and threatening global food inflation.

The effective closure of the Strait of Hormuz has choked shipments of urea, a key component in nitrogen fertilizers, leaving large volumes stranded in the Gulf and tightening supplies for farmers around the world. At the same time, Iranian drone attacks on nations including Qatar and Bahrain have damaged energy and industrial infrastructure, hindering production of the chemical itself.

That has forced urea manufacturers in the region to curb operations, with 55% to 60% of output potentially halted, according to consultancy CRU Group.

The Middle East is a vital supplier of nutrients for staples like corn, wheat and rice, and a key source of ingredients for their production elsewhere. With the war crimping supplies of crop inputs and leaving countries already exposed to hunger even more vulnerable, there have been calls to open a safe shipping route for fertilizer and other goods to prevent a humanitarian crisis.

The situation could get even worse. Producers have been able to use vessels locked in the strait as a means of storage, ready to move once the waterway reopens. But with efforts to resume peace talks stalled and the route still essentially closed, laden ships cannot exit and empty ones aren’t coming in.

“The longer this situation lasts, the greater the risk that producers are forced to shut down because storage fills up and there is simply nowhere left to put the product,” said Pranshi Goyal, a senior analyst at CRU. “If that happens, the disruption becomes even more severe, as nitrogen plant restarts are not a switch.”

Iran has signaled it may be willing to accept an interim deal to reopen Hormuz in exchange for Washington ending its blockade of Iranian ports, while postponing more complex negotiations over the country’s nuclear program. U.S. President Donald Trump convened his national security team to discuss the proposal.

Roughly 45% of global urea trade comes from producers with manufacturing sites on the Persian Gulf and is shipped to major import regions including India, Europe and Brazil, according to Bloomberg Intelligence. Urea is also difficult to replace — it’s the most widely used nitrogen fertilizer and has a higher nutrient concentration than many alternatives.

Since the Iran war began at the end of February, only 11 ships laden with fertilizer have transited the waterway, according to ship-tracking data compiled by Bloomberg and intelligence firm Kpler, with four of those carrying urea. A total of 44 vessels with fertilizer remain stuck in the Persian Gulf, with almost half of them laden with urea.

“The market problem is not just lost production, but product that cannot move,” Goyal said. Even if the strait reopens, “the backlog is unlikely to clear quickly, and the market impact will continue to compound.”