The key focus areas of MACC 2023

A pathway for the Irish agricultural industry to meet its greenhouse gas (GHG) targets by 2030 was presented on Wednesday, July 12th, when Teagasc launched the Marginal Abatement Cost Curve (MACC) 2023.

The agriculture sector must reduce from the 2018 level of GHGs of 23MT CO₂ eq per year, by 25% to 17.25MT CO₂ eq per year by 2030. The new MACC shows this can be achieved. However, an ambitious level of technology adoption by farmers to mitigate GHGs is required. Read more on how this reduction can be achieved here.

Professor Gary Lanigan, one of the authors of MACC 2023, introduced the technologies – some already available and being implemented on Irish farms and some future technologies – which farmers and the wider agricultural industry must embrace to ensure the targets are achieved. He broke the implementation of these technologies down into two periods – carbon budget one, which runs from 2021-2025 and budget two from 2026-2030.

“Most of the heavy lifting will be done during the second budget, but a lot of the targets – particularly in terms of nitrogen use will be during the first carbon budget,” Gary outlined at the launch of the MACC. To reduce nitrous oxide emissions, the target for reducing nitrogen fertiliser use as set out in the MACC by 2030 is 30%.

Ireland is in a fortunate position in this regard, he explained, as previous research undertaken in Teagasc Johnstown Castle has focused on the advancement of our national inventory in terms of nitrous oxide.

Professor Gary Lanigan speaking at the launch of MACC 2023

Pointing to the ways in which this nitrogen reduction target can be achieved, he said: “First of all, get your soil pH correct; two-thirds of our soils are sub-optimal pH. Secondly, get your soil P (phosphorous) and K (potassium) index right.” On the latter, Teagasc Johnstown Castle research has shown that soils with a P index of 3 have lower nitrous oxide emissions than at P index 1 or 2. The use of legumes such as white and red clover was also presented, as these crops have the potential to fix nitrogen (N) from the atmosphere, thus displacing some of the requirement for artificial N forms.

On fertiliser applications, he noted: “It is really going hard at reducing the amount of nitrogen fertiliser. And, if you do have to apply nitrogen fertiliser, then don’t use Calcium Ammonium Nitrate (CAN).

“Patrick Forrestal, my colleague in Johnston Castle, has shown time and again that protected urea works just as well as Calcium Ammonium Nitrate and it’s cheaper. The nitrous oxide emissions are one-third of those from Calcium Ammonium Nitrate and it has low ammonia emissions.”

Key measures to reduce nitrous oxide from MACC 2023:

• Management of and reductions in use of nitrogen fertilisers should be the first focus. This can be achieved through a combination of reduced N fertiliser application and altered fertiliser formulation (either protected urea or ammonium-based compound fertilisers).
• Key technologies for achieving a reduction in nitrogen fertiliser use include the greater use of white and red clover, achieving optimum soil pH and soil P/K status in combination with enhanced use of legumes and multi-species swards and the use of Low Emissions Slurry Spreading (LESS). These can reduce fertiliser use to between 322,590t (N) and 285,727t (N) by 2030.
• Altering fertiliser formulation (switching from CAN to protected urea or an ammonium-based compound) will reduce emissions in 2030 by 553kt CO₂ eq per year. Reduced crude protein in animal feed concentrates will also contribute to reduced nitrogen loading in soils.

Other measures

The second budgetary period, Gary outlined, will really start to tackle methane through improved animal genetics – particularly dairy EBI and beef genetics – but also then the use of feed additives.

The route to achieving the GHG reduction has been far more ambitious with feed additives, Gary explained: “We are implementing feed additives during grazing to about half of the dairy herd and then to about 65% of the bovines during the housing period.” A reduction in the age of finishing of prime cattle by three months is also targeted. Diversification of on-farm activities to include organics, forestry and feedstock production for the bio-methane industry were also included and the potential impact these may have on livestock numbers. Some of the key measures and changes required are outlined in table 1 below.

Key points of methane mitigation from MACC 2023:

• Reduced age at finish could reduce emissions in 2030 by 732kt CO₂ eq per year. This is equivalent to a reduction of average finishing age by three months.
• EBI could reduce absolute levels of methane by 255kt CO₂ eq per year by 2030.
• Feed additives that inhibit methane production in the rumen could reduce methane emissions in 2030 by 788kt CO₂ eq per year. These still require a lot of research for development and deployment.
• Diversification into organic farming, forestry or particularly feedstock (grass) production for bio-methane production could reduce emissions in 2030 by between 150kt CO₂ eq per year and 417kt CO₂ eq per year.
• Manure management, in terms of slurry additives and aeration but also bio-methane and extended grazing could reduce manure methane emissions by between 423kt CO₂ eq per year and 879kt CO₂ eq per year by 2030.

Table 1: Uptake rates of measures – 80% of total mitigation

 More information on MACC 2023 is available here.

Also read: The MACC from a tillage perspective