Fertilizer shipments through the Strait of Hormuz have begun to pick up following the interim agreement to end the war with Iran, according to shipping data, though analysts caution that a return to pre-conflict volumes—and meaningful market relief—will take considerable time.

Before the U.S. and Israel launched the war on Feb. 28, roughly one-third of globally traded urea—the world’s most widely used fertilizer—and nearly half of seaborne sulfur, a key input, typically passed through the strait. The near-total closure of the waterway for most of the conflict drastically curtailed those shipments. Since the Washington-Tehran deal was announced on June 15, about 640,000 metric tons of sulfur—critical for producing fertilizers like diammonium phosphate (DAP)—have left the strait for destinations including Indonesia, Morocco, Tanzania, and China, according to the latest flow analysis by price reporting agency Argus. That compares to a total of just 80,000 tons over the course of the 3½-month war. Some 427,000 tons of urea have also transited the strait since the deal, versus 275,000 tons during the war, according to the latest data from consultants CRU. Shipments of other key fertilizers like phosphates and the fertilizer input ammonia have also edged up post-deal.

Fertilizer prices spiked during the war, prompting farmers to apply less product to their crops and raising concerns that a prolonged closure of the strait could blunt crop yields and trigger a global food price crisis. While traffic has picked up this week, over 500 ships remain stranded in the Gulf, and daily transits remain a fraction of the average of 125 ships per day that used the waterway before the war.

“The flows trickling through the strait are a relief. But at the same time, the majority will be against old sales. They’re not going to provide fresh tonnages to the market,” said Sarah Marlow, head of fertilizer pricing for Argus. While bulk carriers are slowly exiting the strait, no empty carriers are heading back in to collect new cargoes, Marlow added, noting that traders are striking very few fresh fertilizer sales deals in the region.

For carriers to return, analysts say, many war-related obstructions must first be removed. The waterway needs to be successfully de-mined, the current vessel backlog must be cleared, and shippers need to feel confident sailing back in. The interim U.S.-Iran deal must also result in a permanent truce. However, the U.N. International Maritime Organization had to pause its operation escorting ships through the strait on Thursday after a vessel reported an attack, raising fresh concerns over whether the deal will hold.

“Fertilizer volumes through the strait are not going to be at pre-conflict levels for some time,” said Willis Thomas, chief fertilizer analyst at CRU. “Even in a best-case scenario, August is the earliest we see a significant pickup in traffic.” There are still around 600,000 tons of urea stuck inside the strait, according to CRU, while Argus estimates 300,000 to 400,000 tons of sulfur are waiting to exit the waterway.

Fertilizer production facilities in the Gulf were also attacked during the war and need to be repaired. While experts say the damage is relatively limited, it will still slow the rate at which fertilizer price spikes can unwind. “Fertilizer production in the Gulf could mostly recover,” said shipping association BIMCO. “However, exports from Qatar and the United Arab Emirates could remain below pre-war levels (in the medium term) since they sustained damage to gas fields and refineries.”