Carbon emissions associated with the next generation of fertiliser manufacture could be reduced by up to 90%, but the technology requires “eye watering sums of investment,” a senior figure from Yara UK has said.

Addressing a Yara conference on knowledge exchange at CAFRE Greenmount, Mark Tucker outlined the various options to produce ammonia, which is the key chemical used in the manufacture of fertiliser.

Currently ammonia is produced from a process that relies on hydrogen from natural gas and nitrogen from the air. However, carbon dioxide (CO2), which is a main greenhouse gas (GHG), is released during manufacture. In addition, when ammonia is converted to nitric acid to produce nitrate fertiliser, the potent GHG, nitrous oxide (N2O) is emitted.

In Europe, catalyst technology invented by Yara has significantly reduced N2O emissions, meaning European fertiliser has a lower carbon footprint per unit than other regions. However, the overall production process still carries a lot of carbon emissions.


During his presentation, Tucker outlined two main solutions. The first involves capturing the carbon released during ammonia manufacture and putting it into long-term storage underground.

Known as “blue ammonia”, in November 2023 Yara confirmed it will be investing in the technology at its Sluiskil ammonia production site in the Netherlands, where CO2 will be captured, liquefied and transported to Norway for injection 2.6km below the seabed.

A similar project in Texas, in partnership with Canadian company Enbridge, is expected to cost up to $2.9bn and should start production in 2027/2028.

“It is a huge investment to take that carbon and bury it,” said Tucker.

The other solution is “green ammonia” where hydrogen for the ammonia production process comes from water electrolysis, while energy to power the factory is from renewables such as wind or solar.

In early 2022 Yara announced it had signed a contract to build a demonstration plant in Norway to produce green ammonia and ultimately up to 60,000t of fertiliser per year.

According to Tucker, the technology is “game-changing but also challenging” and while it has virtually zero emissions, it does come at high cost.

“There are financial gaps to overcome. The costs are three to four times more to produce through electrolysis,” he said.

But while technology can help solve GHG emissions during manufacture, over half of all current emissions associated with fertiliser occur in the field (mainly N2O losses), so further research and innovation will be required.

Organic fertiliser

There is also the option of organic based fertilisers, with Yara investing in a number of companies with the aim of supplying organo-mineral fertiliser. These fertilisers use organic waste which is then fortified with the likes of nitrogen. A Yara Nature 8-3-3 is now on the market. According to Tucker, the next stage is to scale up production, potentially building sites close to reliable sources of organic material. “We are open to the whole concept of building facilities in Ireland,” he said.

Switch from CAN could limit choice

A DAERA consultation in 2023 suggested that straight urea should be banned because it is associated with high losses of ammonia and instead, protected urea should be used.

The benefit of any urea product over CAN is that it is associated with much lower losses of nitrous oxide (N2O) when spread.

Taking both issues together, it is likely the pressure will grow on farmers to choose protected urea as their main source of nitrogen.

However, given fertiliser merchants in Europe have “easy access” to CAN, removing it from local supply could potentially have implications for competition in the market.

“If we take CAN out, yes, we are reducing our choice,” acknowledged Eva Ross from Yara.

Consistent drop in NI fertiliser sales

Historic data published by DAERA shows that total fertiliser sales peaked at 529,000t in 1995, but since then they have generally been in consistent decline, with just 250,400t sold in 2022 Over the same period, the amount of concentrate feed is up by around 60%.

Given our competitive advantage is the ability to grow grass and other herbage, Yara agronomist Philip Cosgrave questioned whether this trend is right for NI agriculture.

He acknowledged that phosphorus (P) from bagged fertiliser has contributed to water quality issues in NI, but argued that P from animal feed “will be far trickier to correct”.

“All the gains made by reducing nitrogen purchases are lost through purchase of that feed – we could see why it happened in 2022 [due to high fertiliser prices], but not in 2023. Milk from forage is going down, which is very worrying,” he said.


With the increased interest in growing clover as a means of fixing nitrogen (N), he reminded farmers that clover might not require bagged N, but still needs to be supplied with potassium, phosphorus and sulphur and likes a soil pH above six.

“We are going to have to change the type of products we have to meet the requirements of these crops,” said Cosgrave.

NI farmers taking on the lime message

While results from Zone 1 of the soil nutrient health scheme (SNHS) suggest around 60% of fields tested need lime to correct low soil pH, the situation is potentially worse in Britain, suggested Jon Telfer from Yara Analytical Services.

He told last Thursday’s conference that since 1990, the average pH across the UK has dropped by half a unit (based on 2m results), although across 35,000 soil samples taken in NI over the last five years, pH has been going up and averages around 6. “The message is perhaps getting through here. There are lots of soil micro-organisms that like a pH of 6 to 7,” said Telfer.

As well as soil pH, he reminded farmers to ensure phosphorus (P), potassium (K) and sulphur (S) are adequately supplied. In controlled conditions in a glasshouse, where a deficiency of each nutrient was created, it resulted in a respective 57%, 34% and 26% loss in grass biomass yield.

Between one quarter and one third of soils tested in NI are deficient in P and/or K. However, there are also a significant number of soils above the optimum for the likes of P (Index 2+) which means there is no advantage applying the nutrient and where P is spread, there is an increased risk of losses to the environment.

Telfer also encouraged farmers to consider other nutrients, especially calcium, which is a key plant nutrient and important for soil structure and animal health.

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