The reason is fertilizer.
Modern farming depends heavily on nitrogen fertilizer, and nitrogen fertilizer depends heavily on natural gas, energy markets, shipping routes, and a handful of chokepoints. One of the most important is the Strait of Hormuz. When conflict disrupts that corridor, the effects do not stop at oil prices. They move into fertilizer markets, then into planting decisions, then into crop yields, food prices, and eventually hunger risk.
That is the part of the story that is easy to miss. Food crises do not always arrive all at once. Sometimes they begin as a shipping problem, become a fertilizer problem, and only later show up as a harvest problem.
The Strait of Hormuz disruption has already tightened fertilizer supply and pushed prices higher. The World Bank reported that its fertilizer price index rose sharply in early 2026, while FAO has warned that fertilizer scarcity tied to the Strait of Hormuz crisis will affect coming harvests and food supplies in the second half of 2026 and into 2027. UNCTAD has made the same basic point: disruptions in energy and shipping are now directly linked to agricultural markets and future food supply.
That is the first point worth saying plainly: this is not only an energy shock. It is a delayed food-production shock.
Farmers can postpone many purchases. Fertilizer is harder to postpone. If nitrogen is too expensive or too hard to get, farmers face three bad choices: pay more, apply less, or take the risk that the crop will come up short. Farmers with strong balance sheets may absorb the cost. Farmers with thin margins may not. In many import-dependent regions, especially where smallholders are already close to the edge, that choice can determine not only this year’s harvest, but whether they can afford the next season’s inputs.
And that is where the soil enters the story.
At a recent 4 per 1000 soil carbon science webinar, two soil scientists asked a deceptively simple question: when does a fertilizer shock actually end?
The intuitive answer is: when the Strait reopens, supply chains normalize, and prices come back down.
But soil ecologist Matt Wallenstein and soil biogeochemist Stuart Grandy argued that the real answer is more complicated. A fertilizer shock does not just hit the market. It hits the soil. And as Wallenstein put it, “the soil has a memory.”
Here is what that means.
When fertilizer becomes expensive, many farmers apply less nitrogen. Less nitrogen usually means a smaller crop. A smaller crop means fewer roots, stalks, leaves, and residues returning to the soil after harvest. Those residues are not waste. They are part of how soil organic matter is rebuilt. And soil organic matter is one of the places where next year’s nitrogen supply is stored.
So one bad fertilizer year can echo forward. Less fertilizer leads to less crop growth. Less crop growth leads to less residue. Less residue leads to less soil organic matter. Less soil organic matter means less nitrogen available from the soil next season. The market shock may pass, but the soil reserve has been drawn down.
That does not mean global yields collapse overnight. They do not. This is where the numbers matter.
A separate statistic often used in food-system debates says that without synthetic nitrogen fertilizer, the world could feed far fewer people — roughly half of humanity depends, directly or indirectly, on industrial nitrogen. That is a big, long-term structural fact about modern agriculture.
But the Iran war is not removing all synthetic fertilizer from the world. It is disrupting part of the supply system. Farmers still have some fertilizer. They ration it. They shift it to their most responsive fields. They draw on soil reserves. They change plans. Markets adjust. Governments intervene. Trade reroutes where it can.
That is why the first yield effects modeled in Wallenstein’s work are more modest than the “half the world depends on fertilizer” statistic might suggest. A partial supply shock is not the same as eliminating the entire industrial fertilizer system.
But modest does not mean harmless.
In Wallenstein’s model, a short fertilizer shock causes an immediate global yield decline and then a partial recovery. The more troubling scenario is a sustained disruption. If the shock drags on, the initial hit does not simply stay flat. It compounds, because the soil itself is being depleted as each weaker crop returns less organic material to the ground.
That is the quiet danger. Not a single failed season everywhere. A slow weakening of the system’s buffer.
And the buffer is not evenly distributed.
Soils rich in organic matter hold more nitrogen in living and slowly cycling forms. Grandy described this as a kind of bank account. When fertilizer is short, the crop can draw on that account. The healthier the soil, the softer the blow. The poorer the soil, the harder the hit.
This is why soil organic matter should not be thought of only as a climate metric. It is also a food-security asset. It is a risk-management asset. It is a farmer-solvency asset.
The scientists were blunt about the framing: building soil organic matter is insurance for a bad year.
That insurance pays a little every season through better water holding, better structure, better nutrient cycling, and more resilient crops. But it earns its keep when the market lurches. When fertilizer doubles, or supply tightens, or a war closes a shipping lane, the farm with more living soil has more options than the farm that depends almost entirely on purchased inputs.
The flip side is sobering. The places most exposed to fertilizer shocks are often the places with the least cushion: thin soil reserves, heavy import dependence, and farmers with little financial room to absorb a bad year. That is why a fertilizer shock can become a food crisis even if the global average yield decline looks “modest” on paper. A four or five percent global decline can hide much sharper local pain. And for a smallholder farmer, the difference between a manageable season and a failed one may be measured not only in yield, but in cash flow.
This is also why the risk is bigger than one harvest.
Conflict in Iran sparks global fertilizer shortage, threatens food prices
If a farmer cannot afford enough fertilizer this season, yields may fall. If yields fall, income falls. If income falls, the farmer may not be able to buy next season’s seed, fertilizer, or fuel. A market shock becomes a liquidity shock. A liquidity shock becomes a production shock. A production shock becomes a food-supply shock.
The soil keeps the score underneath all of it.
There is a policy lesson here as well. The people who price farm risk — lenders, crop insurers, buyers, governments — mostly still look backward. They look at yield history, acreage, debt, and last year’s numbers. They rarely reward the farmer who has spent years building organic matter, improving nitrogen efficiency, and making the farm less vulnerable to exactly this kind of shock.
That gap matters. If soil organic matter reduces risk, then risk markets should recognize it. If healthy soil protects future harvests, then food-security policy should treat it as infrastructure. Not metaphorically. Literally.
Ports are infrastructure. Grain reserves are infrastructure. Fertilizer plants are infrastructure. So are soils capable of holding water, cycling nutrients, and buffering a bad year.
The Iran war has exposed something that was already true. The global food system is not just dependent on farms. It is dependent on fossil energy, fertilizer trade, shipping lanes, credit, and soil reserves. When one of those pieces breaks, the others have to absorb the shock.
Fertilizer markets will eventually loosen. Ships will eventually move. Prices will eventually settle.
But the soil keeps its own books.
And the farms that have built organic matter will have more to draw on when the next shock arrives.
It’s the soil.
