Wars not only burn cities. They also starve seasons. Since the beginning of the conflict in the Middle East, most of the attention has focused, understandably, on oil, gas and, within agriculture, on urea — that essential nitrogen fertiliser without which modern maize cultivation becomes an exercise in nostalgia. Prices have surged, shipments through Hormuz have been disrupted, and farmers have begun scrambling for supply. Yet beneath that visible panic, another threat has been gathering with a quieter, and perhaps more enduring, menace: phosphate. This is the more insidious risk. Nitrogen shocks are immediate and theatrical; phosphate shortages are slower, more structural, and therefore potentially more dangerous. They do not merely raise costs for one planting season. They threaten the chemical foundations of global food production.

The Middle East accounts for roughly one-fifth of global trade in three critical phosphate products. That alone would warrant concern. But the deeper vulnerability lies elsewhere, in sulphur. Nearly half of the global sulphur supply — later transformed into sulphuric acid, an indispensable ingredient in the manufacture of phosphate fertilisers — comes from Middle Eastern countries now exposed to disruption in the Strait of Hormuz. In other words, the conflict is not simply constraining one market. It is threatening the raw material behind the market.

And that is how shortages become exponential. Producers can survive for a time by drawing down inventories of sulphur and sulphuric acid. But once those buffers are exhausted, the arithmetic hardens. Phosphate production slows. Prices rise. Buyers compete more aggressively. Supply chains tighten. The shock, initially manageable, becomes structural. This matters far beyond the fertiliser industry. Phosphate is not an optional input. It is essential to the growth of crops ranging from soybeans to potatoes, and therefore to animal feed, food processing and global calorie chains. In the United States alone, around eighty per cent of the phosphorus applied to fields goes onto soybean and maize acreage, which is then transformed into livestock feed and fuel. What begins as a disruption in one commodity market does not remain there for long.

And the market, crucially, was already tight before the war. Sulphur prices had already surged to record levels. Russian supply had been constrained by the war in Ukraine and by export restrictions. China, meanwhile, had curbed phosphate shipments in favour of domestic needs. Demand from mining — which consumes sulphuric acid to extract metals such as copper and nickel — had added further pressure. The system was, in other words, already strained. The war did not create the problem. It merely removed what little elasticity remained. American policy has hardly helped. Tariffs on Moroccan phosphate, introduced earlier and still in force, together with broader trade measures imposed last year, have restricted imports from one of the world’s most important phosphate producers. Protectionism, so often marketed as strategic foresight, has in this case simply made scarcity more expensive. That is why the current anxiety in fertiliser markets is no longer confined to nitrogen. Indeed, one experienced market observer now argues that phosphate is in some ways in even worse condition. Before the war, it already had more than enough problems. The war has merely taken a fragile market and pushed it towards dysfunction. The real constraint, increasingly, is sulphur. And sulphur, unlike oil, does not enjoy the same political visibility. It enters no speeches. It inspires no strategic petroleum reserve. Yet it is used in too many critical sectors to be left solely to fertiliser producers if scarcity deepens. Mining companies, with stronger margins and greater pricing power, may simply outbid agriculture for available supply. In that event, food production will not merely become more expensive. It will become secondary.

This is how inflation becomes embedded — not through one spectacular commodity spike, but through a chain of smaller, industrial dependencies tightening all at once. The market is already beginning to register that possibility. Key sulphur benchmarks in the United States have reached record levels. Diammonium phosphate prices in New Orleans — a reference point for one of the world’s most common phosphate fertilisers — have risen to their highest point in months. Traders now warn that the real impact could begin to bite as early as April, when India traditionally enters the market more aggressively to secure domestic supply. At that point, what is currently tension could become panic. The United States, meanwhile, faces a particularly absurd contradiction. Farmers depend on three major fertiliser groups: nitrogen, phosphate and potash. Of these, potash — much of it coming from Canada — is relatively insulated from the current turmoil. But phosphate is not, and American farm groups are now urging Washington to suspend tariffs on Moroccan fertiliser. Their argument is less ideological than practical: high prices and geopolitical risks have already done more than enough to constrain imports without the additional vanity of trade barriers.

Affordability is already reshaping behaviour. Some producers expect phosphate consumption in the United States to decline sharply over the twelve months through June. Farmers, faced with high nitrogen prices and tightening phosphate supply, may shift acreage away from maize and towards soybeans to control costs. Such decisions, repeated across thousands of farms, reshape not merely farm economics but downstream food and feed balances.

And that is the larger point. Food systems do not collapse in one dramatic moment. They fray. Input by input. Shipment by shipment. Acre by acre. The danger here is not only that spring planting becomes more expensive. It is that, by autumn, the market may simply be exhausted — physically dry, financially stretched, and forced to ration through price what it can no longer provide through flow. That is the true significance of this war for agriculture. Not merely that it has made fertiliser dearer, but that it has exposed how thin the buffer had already become. A market that entered the conflict tight may leave it hollowed out. The oil shock makes headlines. The fertiliser shock arrives later, disguised as yield losses, weaker crop decisions, food inflation, and political denial. But in the end, it may prove to be the more consequential of the two.