Tearing apart the sulphate of potash supply chain

Potash.

Bloomberg ran the headline in May: potash is insulated from the Hormuz crisis. CNBC's fertilizer analyst repeated the thesis last week. The logic is clean — potash comes from Canada and Belarus, nowhere near the Persian Gulf, so it dodges the shipping catastrophe that's been wrecking ammonia, urea, and phosphate since February. Analysts nod. The chart looks calm. Everyone moves on.

They're talking about the wrong potash.

There are two potash products that matter. MOP — muriate of potash — is the commodity grade. Eighty-five to ninety percent of global volume. Mined from underground evaporite deposits in Saskatchewan and shipped through Canpotex. That one is fine. The other is SOP — sulphate of potash — the premium grade used on every chloride-sensitive crop on earth. Grapes. Almonds. Strawberries. Coffee. Tobacco. The high-margin agriculture that actually drives rural land values in California, Chile, and southern Europe.

SOP is not fine. SOP is breaking.

The reason is one ingredient: sulfur. The dominant method for producing SOP is the Mannheim process — reacting MOP with sulfuric acid at high temperatures. No sulfuric acid, no SOP. And sulfuric acid requires sulfur, fifty percent of which transits the Strait of Hormuz. The same chokepoint that shut down ammonia and urea is now quietly strangling SOP from the input side.

Except nobody put SOP in the disruption column. They filed the whole category under "potash: safe" and moved on. It's like declaring the entire house fireproof because the kitchen tiles survived.

Numbers.

The Mannheim process consumes roughly 0.6 tonnes of sulfuric acid per tonne of SOP output — about 0.2 tonnes of elemental sulfur. At current sulfur prices, that translates to an input cost increase of $180–$220 per tonne of finished product versus pre-crisis levels. The math doesn't allow breakeven at historical SOP prices. Full stop.

Pakistan's Mannheim plants — a meaningful share of Asian SOP capacity — cut operating rates from 80–90% down to 50–75% after domestic sulfuric acid prices tripled from Rs 100,000 to Rs 300,000 per tonne between February and April. Those plants haven't recovered. They can't. Not at these feedstock costs.

Meanwhile, MOP sits quiet. India settled its 2026 benchmark contract with BPC at $383/t CFR — a $35 premium over China's $348/t CFR. That's elevated versus the historical average $8 India-China spread, but it's not crisis pricing. Canadian mines are running. Belaruskali is shipping again after Washington lifted sanctions in March. The Canpotex pipeline is full.

Two products that share a name. Two completely different stories. MOP says the world is adequately supplied. SOP says a critical input has been severed. The market is pricing potash as one commodity. It is two. And only one of them is in trouble.

Roughly sixty percent of global SOP production runs through the Mannheim process. Every tonne of it is now hostage to a sulfur market that's been broken since February. The natural sources — the Great Salt Lake at Compass Minerals, evaporite deposits in China and Germany — don't have the capacity to backfill a sixty-percent production cut even if they wanted to.

You can't solar-evaporate your way out of a feedstock crisis on a six-month timeline.

Compass Minerals runs SOP production at the Great Salt Lake — one of the few natural sources in North America. Solar evaporation, no Mannheim, no sulfur dependency. Sounds like a lifeline. Except Compass's Ogden facility produces a fraction of global demand, and the Great Salt Lake itself has been fighting critically low water levels for years. The brine concentrations the operation depends on are not guaranteed. I wouldn't build a thesis on a lake that's been shrinking for decades.

Here's the part that should keep specialty crop buyers awake. SOP isn't optional for their operations. Chloride-sensitive crops — wine grapes, tree nuts, berries, tobacco, coffee — cannot substitute MOP without risking chloride toxicity that damages fruit quality, reduces shelf life, and in severe cases kills the plant outright. The agricultural calendar doesn't negotiate. Southern hemisphere spring planting is weeks away. Northern hemisphere fall application windows are open now.

Every procurement team in the San Joaquin Valley, in Maule, in Puglia is staring at the same spreadsheet and seeing the same number: SOP delivered costs up 40–60% with no relief valve in sight.

I've watched input cost squeezes hit specialty agriculture before — 2008's fertilizer spike, the 2022 post-Ukraine repricing. The pattern is always the same. Growers absorb it for one season, maybe two. Then they cut acreage on marginal land, reduce application rates, and the yield impact shows up twelve to eighteen months later in commodity prices nobody was watching. Almond futures. Wine grape contracts. The second-order effects are where the real repricing lives.

The sequence is already in motion.

If sulfur stays above $800/mt FOB — and with Hormuz still closed, China's sulfuric acid export ban still in force with no end date, and Russia's sulfur export ban extended through December — there's no structural reason for it not to. Mannheim producers don't return to full rates. Period. The bottom sixty percent of cost-curve capacity stays offline or runs at a loss that compounds every quarter.

That tightens SOP supply into the Q4 application window, when demand from both hemispheres overlaps. Southern hemisphere spring planting. Northern hemisphere fall pre-plant. Two demand peaks hitting simultaneously into a supply base that's been running at fifty to seventy-five percent for six months. I traded a compressed fertilizer market once, in 2008. The supply-side math felt manageable right up until the moment it wasn't.

Where does the capital go? Not into the broad fertilizer ETFs. Those are dominated by nitrogen and MOP exposure — the segments where supply is functioning normally. The edge, if there is one, is in companies with natural potash production assets that bypass the Mannheim bottleneck entirely. ICL Group, whose Dead Sea brine-based potash operations sidestep the sulfuric acid bottleneck. K+S, with its Werra basin evaporite deposits in Germany. Compass Minerals, conditional on the Great Salt Lake holding. These are the producers whose margins expand when sulfur prices rise — because their core operations don't depend on it.

The market is pricing potash as a monolith. It isn't. MOP and SOP have diverged further than at any point in the last decade, and the divergence is accelerating. Financial screens say "potash: stable." The loading docks at Mannheim plants in Port Qasim and Rahim Yar Khan tell a different story. They're quiet enough to hear the forklift batteries charging. In my experience, when the factory floor disagrees with the terminal, the factory floor wins. It just takes longer than the quarterly earnings cycle for the screens to catch up.