University of Illinois farmdoc daily on August 25 linked rising phosphate fertilizer costs directly to the sulfur price surge reshaping North American fertilizer markets.
Authors Paulson, Schnitkey, Zulauf, and Dhakal cited Vancouver spot sulfur above $1,000 per ton in recent months.
That level is more than 130% above January 2026 and more than 300% above August 2025 in the farmdoc account.
Corn Belt diammonium phosphate averaged near $850 per ton in recent weeks, up more than 20% from early 2026.
The correlation between Corn Belt DAP and Vancouver sulfur prices since 2024 was positive and statistically strong at 0.70.
The correlation between Corn Belt DAP and anhydrous ammonia prices was similarly strong at 0.65 over the same window.
Producing one ton of DAP requires roughly 1.5 to 2 tons of phosphate rock, 0.4 ton of sulfur, and 0.2 ton of ammonia in the input ratios farmdoc uses.
A several-hundred-dollar sulfur increase is difficult for manufacturers to absorb without raising finished fertilizer prices or cutting run rates.
US net import reliance on sulfur and sulfuric acid stood at 14% in 2024 and 2025 per USGS Mineral Commodity Summaries shares cited in the piece.
USGS 2026 production shares put China at nearly 23% of global sulfur output, the United States near 10%, Russia 8.9%, Saudi Arabia 8.6%, UAE 7.5%, Canada 6%, and Kazakhstan 5.7%.
The authors warned that sharply higher sulfur since February could feed further DAP increases as firms adjust procurement and pricing with a lag.
Farmers entering the fall fertilizer window for 2027 crop decisions face high prices and heightened volatility on both nitrogen and phosphate lines.
Vancouver is the Pacific export benchmark farmdoc charts against Corn Belt DAP. Alberta forming plants and the Vancouver stem are the Canadian supply answer when Gulf molten tightens.
Desk read: farmdoc's 0.70 correlation is the quantitative bridge between Pacific export prices and inland phosphate affordability. Mosaic's Louisiana WARN filing two days later is the production-side echo of the same math.