3rd October 2026
Britain's diesel crisis has so far been discussed mainly in terms of motorists, hauliers and the cost of transporting goods.
But there is another group feeling the squeeze which could eventually affect every household in Britain.
Farmers.
And the problem facing them is bigger than the price of fuel.
Farmers are being hit by rising red diesel costs at precisely the time of year when machinery is working hard in fields, while fertiliser prices remain well above their pre-conflict levels.
There is also growing concern about whether enough fertiliser will actually be available when farmers need it.
That combination could eventually find its way into something considerably more important than the price of filling a tractor.
The price of food.
Red diesel is no longer cheap
Red diesel is the fuel used by farmers for agricultural machinery and is taxed at a lower rate than ordinary road diesel.
But the tax advantage doesn't protect farmers from what is happening in the international oil market.
Farmers Weekly's latest supplier survey puts the average UK red diesel price at around 118p a litre, compared with about 98p at the end of July.
That is an increase of roughly 20p a litre in only two months.
The Agricultural and Horticultural Development Board's August benchmark was lower, at 108.47p, but that was still 19.6% higher than July and 43.3% higher than a year earlier.
And prices have been moving quickly.
Farmers Weekly has reported that some farmers have found themselves paying more than 115p a litre, while others have seen prices move by several pence in only a few days.
This makes deciding when to buy increasingly difficult.
A farmer who normally buys fuel ahead of a busy period now has to consider whether prices will be higher or lower by the time the next delivery is required.
The Government has already cut the tax
There is an important point here.
The increase isn't simply the result of higher tax.
In June the Government reduced the duty on red diesel from 10.18p to 6.48p a litre, its lowest rate in more than 20 years.
The Government has said the cut is intended to support farmers and fishers during the fuel-intensive period.
But the international price increase has overwhelmed that reduction.
In other words, the Government has taken some tax off the fuel while the international market has put considerably more back on.
That is something worth remembering when the impact eventually reaches food prices.
Fertiliser could be the bigger problem
Diesel is relatively easy to understand.
Farmers put fuel into tractors and machinery and pay more when the price rises.
Fertiliser is more complicated.
Nitrogen fertiliser is closely linked to natural gas prices because gas is a major component of the production process.
AHDB estimates that gas accounts for around 60% of the cost of producing fertiliser.
And there is another problem.
Around 35% of global urea exports pass through the Strait of Hormuz.
That means the same geopolitical crisis affecting oil supplies can also affect the production and movement of one of the most important agricultural inputs in the world.
Prices are already significantly higher
The latest AHDB figures show just how much the increase has already fed through.
On 25 September, UK-produced ammonium nitrate averaged £484 a tonne.
That was £82 a tonne, or 20.3%, above the February 2026 pre-conflict level.
Imported ammonium nitrate was £488 a tonne, £84 or 20.8% above February.
Nitrate sulphur was £482 a tonne, 20.4% above February.
Urea was less dramatically affected at £477 a tonne, but was still £22, or 4.8%, above its February level.
And these are delivered-to-farm spot prices, excluding VAT.
For a farmer buying hundreds of tonnes, relatively small movements in the price per tonne can therefore become substantial sums.
But availability could become the next problem
This is where the story becomes more worrying.
It isn't simply that farmers are being asked to pay more.
They also have to make sure the fertiliser actually arrives when they need it.
AHDB reported in September that merchants and buying groups were able to fulfil most orders, but only 75% of nitrate sulphur orders were being fulfilled within 28 days.
Some deliveries were taking as long as six weeks.
AHDB has warned that the fertiliser supply chain has practical limitations.
Fertiliser has to be manufactured or imported, transported through ports, stored, processed or blended, bagged where necessary and then delivered by road.
Every part of that chain has limited capacity.
If large numbers of farmers delay their purchases and then all try to order at the same time, the problem could therefore become a shortage of delivery capacity, even if there is theoretically enough fertiliser somewhere in the world.
That is a subtle but important distinction.
Britain might not actually be "running out" of fertiliser.
Farmers could nevertheless find themselves unable to obtain the particular product they need when they need it.
Farmers normally plan ahead
Agriculture doesn't work like filling the car.
A motorist can see the price has risen and decide to postpone filling the tank for a few days.
A farmer can't necessarily do that.
Crops have growing seasons.
Fertiliser has to be available at particular stages of crop development.
And farmers traditionally buy many of their inputs ahead of the season, partly to secure supplies and partly to manage prices.
That is why the current uncertainty is particularly awkward.
AHDB says many farmers have understandably been cautious about committing to purchases because of uncertainty over prices, cropping decisions, cashflow and the weather.
But the industry is now warning that waiting too long could create a bottleneck.
It is a classic supply-chain dilemma.
Buy early and risk paying too much. Wait and risk paying even more — or not getting what you need when you need it.
And eventually the bill reaches the supermarket
This is the part that consumers should watch.
Farmers cannot simply absorb every increase in their costs indefinitely.
A farmer has to pay for fuel, fertiliser, machinery, labour, repairs, feed and other inputs before producing a crop or livestock product.
If the cost of production rises significantly, there are only a limited number of places the extra cost can go.
It can reduce the farmer's margin.
It can result in less fertiliser being used.
It can influence what farmers choose to plant.
Or, eventually, some of the additional cost can be reflected in the price paid further along the food chain.
That doesn't mean a 20% increase in fertiliser produces a 20% increase in the price of bread, milk or vegetables.
The relationship is much more complicated than that.
But it does mean that farm input inflation today can become food-price inflation tomorrow.
The 2027 harvest may be where we really see it
There is another reason this story may become more important over the coming months.
Much of the fertiliser required for crops already in the ground may already have been purchased.
That means the full impact of today's higher prices doesn't necessarily appear immediately in supermarket prices.
Instead, farmers making decisions about the next growing season may face a much higher cost base.
AHDB has already noted that most arable farmers had bought fertiliser for this year's crops, with the increased prices increasingly becoming an issue as businesses plan for the 2027 harvest.
That creates a delayed effect.
The headlines today might be about American aircraft carriers, Iran and the Strait of Hormuz.
Several months from now, the consequences could be appearing in farm accounts.
And after that, potentially in food prices.
Britain needs to watch more than the price of oil
This is why the Middle East crisis is becoming much more than an energy story.
The chain looks something like this:
Conflict → oil and gas disruption → higher diesel prices → higher fertiliser production costs → higher fertiliser prices → supply-chain pressure → higher farming costs → pressure on food prices.
It doesn't happen overnight.
And there are plenty of factors which can interrupt the chain.
Oil prices can fall and shipping can recover.
Governments can release emergency stocks.
Fertiliser manufacturers can increase production and Farmers can change what they grow or how much fertiliser they use.
But the risks are now becoming visible.
The UK Government says the country remains well stocked with fuel, while it is monitoring fertiliser markets.
That is reassuring.
But it doesn't remove the underlying problem of higher costs and a supply chain with limited spare capacity.
From the tractor to the supermarket shelf
The important point is that farmers aren't some distant part of the economy whose problems have little to do with the rest of us.
They are at the beginning of the food supply chain.
When their costs rise, eventually someone has to pay.
And that means the price of red diesel may be worth watching even if you have never owned a tractor.
The same is true of fertiliser.
The price of a tonne of ammonium nitrate may seem a long way removed from the price of a loaf of bread.
But it isn't.
It is one of the costs involved in producing the grain from which that loaf is made.
So while the world's attention remains fixed on the military buildup in the Middle East, Britain's farmers are looking at something much closer to home.
Can they get the fuel and fertiliser they need — at a price that still allows them to produce food profitably?
That could turn out to be one of the most important economic questions of the months ahead.
Because the next stage of the Middle East crisis may not arrive with another explosion.
It may arrive quietly, through the farmer's fuel tank, the fertiliser order and eventually the price on the supermarket shelf.