Taxing nitrogen: pros and cons

During the ORFC 2019, a debate took place to explore the potential benefits and unintended consequences of the controversial proposal of introducing a nitrogen tax.

Nitrogenous fertiliser usage is rising; according to the FAO, we’re predicted to use 118 million tonnes globally every year by 2020. There was therefore a consensus within the panel that something must be done to reduce this usage, and a nitrogen tax was tabled as a potential instrument for reducing farmer reliance on artificial nitrogen.

The panel consisted of Dinah Hillier (Thames Water), Honor Eldridge (Sustainable Food Trust), Helen Browning (organic farmer), Robert Craig (conventional farmer), and Jenny Hawley (Plantlife).

Why do farmers need nitrogen?

The Haber-Bosch process has inarguably contributed hugely to productivity capabilities in the last century, and has therefore had a huge impact on social and urban development. Artificial nitrogen (N) can be used to stimulate plant growth, so its introduction led to unprecedented yields and therefore associated reductions in food prices (although the costs have arguably increased; see this report by the Sustainable Food Trust on the ‘true cost of food‘).

Photo credit: OMEX UK

Why is excess nitrogen a problem?

Nitrogen is an abundant key element; around 70% of air is comprised of nitrogen. However, excess N in both water and air can have detrimental effects on resources and ecosystems. Nitrogen promotes the rapid growth of algae; this can lead to eutrophication, suffocating wildlife and even leading to toxic algal blooms when present in excess amounts.

A severe cause of eutrophication in a drainage ditch in Suffolk. Photo credit: Geography Photos

There are different forms of nitrogen, all of which can have detrimental effects to soil, water, and air. N fixation leads to the formation of various nitrogenous compounds. The main pollutants derived from nitrogen are ammonia (formed when N is ‘fixed’ with hydrogen), nitrates, and nitrites.

Excess nitrates/nitrites in drinking water can cause blue baby syndrome, a dangerous condition seen in infants. Water companies must prevent this from occurring by complying with drinking water standards, so if levels of nitrate in their sources exceed a certain level, they have to install costly treatment works to remove the nitrates.

Excess ammonia, often derived from intensive units (particularly poultry) can lead to lichen deterioration and loss; lichen is a key indicator of air quality, so its loss conveys a reduction in surrounding air quality.

Lichen: An under-appreciated tool for monitoring air quality. Picture credit: Scotland’s Environment Web

Much of the nitrogen currently being applied to fields isn’t successfully incorporated into crops, making it increasingly costly for farmers to use; more than half of applied nitrogen is now washing from fields straight into rivers.

Global nitrogen-use efficiency (NUE) in farming has fallen from over 50 percent in 1961 to around 42 percent today, according to Xin Zhang, an environmental scientist at the University of Maryland.

More than 96% of England’s semi-natural wildlife habitat already has excess nitrogen in its soil and water.

Jenny Hawley, Plantlife

However, although artificial nitrogenous fertilisers are undoubtedly the biggest contributor to excess nitrogen from agriculture, Helen Browning pointed out that even non-artificial excess nitrogen can cause pollution; the organic methods of increasing N availability (e.g. legumes) can also lead to water/air quality issues if managed incorrectly.

How would the proposed tax work?

The proposed tax would follow a similar pricing structure to the Finnish fertiliser tax which was introduced in 1992, whereby farmers are charged £0.65 per kg of nitrogen. Honor Eldridge outlined a possible scenario to illustrate how much income this figure could generate in the UK:

  • According to Defra, 91kg/hectare of nitrogen is required in crops and grass, which equates to £59.15 per ha (£0.65*91)
  • There are 11.5 million ha of agricultural land, which means the tax could generate around £680 million (£59.15*11.5m)

Pros of taxing nitrogen

The majority of the panel appeared to agree that although a nitrogen tax may not lead to an immediate reduction in N usage, it may trigger farmers to consider their actions before application, eventually leading to reductions as farmers explore alternative options such as legumes or precision farming.

Furthermore, the funds generated from the tax could be ring-fenced to reward farmers who are adopting natural nitrogen methods and to financially support legume rotation and possibly even investment in precision farming.

Cons of taxing nitrogen

Robert Craig, the only ‘conventional’ farmer on the panel, argued that a nitrogen tax wouldn’t make any significant difference to his usage, as N isn’t one of his largest costs so isn’t of particular concern. He instead suggested that a viable alternative is needed to help farmers reduce their N inputs whilst continuing to produce food profitably.

He also pointed out that yields could be halved if he was no longer able to purchase nitrogen. If cheap imports were allowed after Brexit he wouldn’t be able to compete, as it would become too expensive for him to produce the high yields needed to keep prices down; he claimed that the prices of milk and cheese would have to double to allow him to stop using additional N and to continue producing. This consequence, although unintentional, could be detrimental to UK agriculture. Whether this issue arises depends largely on how future imports are handled by the government when negotiating Brexit.

Alternative solutions

Honor Eldridge also mentioned a few alternative options for reducing farmer reliance on nitrogen, including:

  1. Expanding Nitrate Vulnerable Zones (NVZs)
  2. Improving enforcement from the Environment Agency (in my opinion this needs to happen anyway; continual funding cuts have left insufficient feet on the ground for neither advice nor inspections!)
  3. The government’s Clean Air Strategy (due to be published any day now)
  4. Increased collaboration with private utility companies
  5. Supporting precision technology, for example through interest free loans
  6. Incentivising buffer strips to reduce runoff


If a nitrogen tax were introduced, a potential way to ensure farmers continue to have nitrogen availability without damaging the environment could be to use a portion of the ring-fenced money to research ways of helping farmers to reduce their reliance on artificial nitrogen. There hasn’t been enough research on viable ways of making nitrogen available without losing it from the soil, and the research that has been carried out hasn’t necessarily been disseminated. This research must be carried out independently of large agri-chemical companies, so will therefore need public funding.

Precision farming and other methods such as increased legume cover cropping could provide a viable alternative to artificial N fertilisers, but at the moment the jury appears to be out as to whether a nitrogen tax is the best way to get us there.

Either way, the environment is breaking down; our soils are being lost faster than they can recover and only 14% of watercourses in England are healthy; whichever option the government decides upon, it needs to happen now, and quickly.

Further reading

Weaning ourselves off nitrogen – Sustainable Food Trust

A nitrogen tax for agriculture? – Arc 2020

Opinion: Will nitrogen be taxed? It might just happen – That’s Farming

What do you think?

I’d love to hear from readers about any additional benefits or potential consequences of a nitrogen tax or whether there are any other options which could help to reduce artificial N usage in future.

One thought on “Taxing nitrogen: pros and cons

Add yours

  1. AN interesting article, Thanks!
    The Nitrogen fertiliser that farmers use is already very expensive, especially in relation to the low prices that supermarkets pay farmers for food. No farmer can afford to lose any of it.

    The leakage into ditches etc. indicates a stupid or ignorant farmer, or one who has suffered a horrendous accident, such as a fertilizer store fire or flood,

    Nitrogen pollution can also happen when clover containing leys (often on organic farms) are ploughed up, and the N in the crop leaches out .

    Rather than tax nitrogen it would be much more productive to reinstate the old Farm Management Training Courses, and the National Agricultural Advisory Service, so that farmers and farm managers are taught to manage fertiliser at the beginning of their careers, and can ask for local experienced advice at short notice without it costing anything. Paying for commercial consultancy when your barn has just burned down is not as high on the farmers list of priorities, as replacing lost material may be very urgent.

    Most commercial advice these days comes from the chemical companies anyway, and they will always try to persuade you to buy at least 20% more fertiliser than your land will stand.

    Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Blog at

Up ↑

%d bloggers like this: