12 December 2023

Irish farmers achieve key 2030 nitrogen fertiliser reduction target

Recently published figures from the Department of Agriculture, Food and the Marine (DAFM) have highlighted the progress Irish farmers have made in terms of reducing their nitrogen fertiliser usage – a key step in achieving agriculture’s emission reduction targets.

Through a combination of changed practices at farm level, which encompasses a greater uptake of soil sampling and the tailoring of fertiliser plans based on soil and crop requirements, and a reaction to higher fertiliser prices as a result of global unrest, fertiliser sales in Ireland declined in 2023. 

The Climate Action Plan 2023 sets a maximum chemical nitrogen use target of 300,000 tonnes by 2030, which is a key greenhouse gas reduction measure for agriculture to deliver a 25% reduction in carbon emissions.

DAFM’s Fertiliser Sales Q4 2023 figures indicate that this target was achieved in 2023, when 280,569 tonnes of chemical nitrogen nutrient were sold – a reduction of 18% on the quantities of chemical nitrogen nutrient sold in 2023, which were 343,193 tonnes. Further details on chemical nitrogen use for the period 2018 to 2023 are available in table 1 below.

Commenting on this reduction, Mark Plunkett, Training and Development Specialist with the Teagasc Signpost Programme, said: “Chemical nitrogen use of 280,569 tonnes is well below the Climate Action Plan target of 300,000 tonnes by 2030.

“The 18% reduction of chemical nitrogen will feed into reducing the sector’s greenhouse gas emissions for 2023. Chemical nitrogen use is 31% lower in 2023 than the base year of 2018. This large reduction in chemical nitrogen shows that farmers are being strategic in their use of fertiliser on farm. This reduced nitrogen use is being underpinned by increased use of soil analysis, lime, cattle slurry, clover and multispecies swards on farm.”

Table 1: Chemical nitrogen use for the period 2018 to 2023

Source: DAFM Fertiliser Sales Q4 2023

Nitrogen sources

Of the total nitrogen tonnage sold in 2023, DAFM figures show that 56% originated from straight nitrogen products (156,342 tonnes), whereas 44% was derived from compound fertilisers (124,227 tonnes).

In terms of the straight nitrogen fertiliser component, 29% was in the form of unprotected urea, 22% was protected urea and 49% was Calcium Ammonium Nitrate (CAN).

The Climate Action Plan 2023 targets 90-100% uptake of protected urea on grassland farms by 2030. Commenting on this, Mark said: “Protecting all the straight urea used by farmers would make a huge difference to meeting our national ammonia targets now and into the future. The use of protected urea nitrogen in compound fertiliser such as 29-0-14+ S increased from 547 tonnes in 2022 to nitrogen to 1,427 tonnes nitrogen in 2023.

“This gives a total tonnage of protected urea of 35,427 tonnes, which is a 15% increase in protected urea. Urea and protected urea now make up a combined 52% share of the straight nitrogen market and if all this was protected, farmers would be almost be 54 to 60% of the way towards the 2030 protected urea target.”

Mark noted that maintaining the reduction observed in 2023 is critical into future years and farmers should continue to make adjustments to chemical nitrogen applications for improvements in soil pH and fertility, cattle slurry nitrogen, and increasing the adoption of clover and multispecies swards. A further move from straight CAN to protected urea in 2024 will further reduce greenhouse gas emissions.

Soil fertility

Additionally, although farmers have made reductions in the volume of chemical nitrogen applied, he noted that a decline in the quantities of lime,  phosphorous (P) and potassium (K) purchased are a concern, as good Nitrogen Use Efficiency (NUE) hinges on good lime, soil P and K fertility.

On the use of P and K fertilisers, Mark said: “It is essential that sufficient soil P is available to maximise the utilisation of each kilogram of nitrogen applied. Trials from Johnstown Castle show that moving from soil P Index 1 to Index 3 increases soil N efficiency by 15%. The usage of chemical P has fallen by 10% in 2023, resulting in mining soil P reserves, thus reducing overall farm soil fertility. Since 2021, P use has dropped by 33%. The Teagasc MACC Curve identifies a national annual P requirement of 46,000 tonnes to maintain good soil fertility.

He continued: “To sustain lower chemical nitrogen use in the years ahead, sufficient levels of soil K will need to be applied to maintain good soil fertility levels. The usage of chemical K has fallen by 12% in 2023, which will mean farmers are drawing down soil reserves. Since 2021, K use has dropped by 33%. The Teagasc MACC curves identifies a national annual K requirement of 120,000 tonnes to maintain good soil fertility.”

On lime usage, the Training and Development Specialist with the Teagasc Signpost Programme noted that to build and maintain optimum soil pH levels, Irish farmers need to be spread in the region of 1,500,000 and 2,000,000 tonnes of lime per annum. Although 1,386,917 tonnes were used in 2022 and 1,333,100 tonnes in 2021, he noted that 2023 applications will be back due to poor weather conditions, with estimates pointing to a usage of ~800,000 tonnes.

Despite this reduction, Mark encouraged farmers to apply lime based on recent soil test results to optimise soil pH levels and to adjust lime applications on low input grass swards to maintain sward biodiversity levels.

“This will be the basis to sustaining reduced levels of chemical nitrogen,” he said. “For example, soils can release up to 70kg of nitrogen per hectare per year where soil pH is correct. This offers a large saving in reducing fertiliser nitrogen costs. Every opportunity should be taken to apply lime during the growing season. At current fertiliser prices, lime is the cheapest form of fertiliser as it can unlock naturally occurring nitrogen and phosphorus from the soil,” he said.

Impact on emissions

Mark also highlighted how the reduction in fertiliser use in 2023 is likely to lead to a 1.6% reduction in agricultural greenhouse gas emissions relative to 2022. A similar reduction of 1.8% was seen in 2022 (compared to 2021).

“This reduction in emissions is driven by a combination of factors such as a reduction in chemical nitrogen use, a reduction in CAN type fertilisers and an increase in the use of urea-based fertilisers in the last two years.

“For future years, the challenge will be to maintain fertiliser nitrogen usage levels at or below 300,000 tonnes per year, while increasing the proportion of protected urea and ammonium-based fertiliser use will further reduce greenhouse gas emissions. Since 2018, fertiliser carbon emissions have reduced by 0.9Mt CO₂ eq or 35%,” Mark said.

Additional information

Mark recently featured on an episode of the Teagasc Signpost Series, where he discussed past, current and future fertiliser usage. This webinar is available here.