Global warming is an issue that concerns everyone, and the farmers involved in the second phase of the Dairylink programme have been addressing the issue by carbon benchmarking their businesses and discussing options for mitigation.

The buildup of greenhouse gases (GHG) in the atmosphere such as methane, nitrous oxide (N2O) and carbon dioxide (CO2), trap the sun’s heat, causing increases in temperature, changes in weather patterns and extreme weather events.

At present, the accounting system used to measure emissions attributes 26% of all greenhouse gases (GHGs) produced in Northern Ireland to agriculture.

With the UK legally committed to a net zero carbon emissions target by 2050, it is clear that the farming industry must start addressing this issue now.

Dairylink farmers began this process in 2021 by carbon benchmarking their businesses through CAFRE.

This allowed them to determine the carbon footprint for their farm, identify the largest contributors to the overall figure and discuss what individual steps they can take to lower it.

What is carbon benchmarking?

Carbon benchmarking is a process that involves collecting details about the inputs and outputs for each farm.

Examples of inputs include purchased feed, fertiliser, fuel and electricity, while outputs include milk and livestock sales and exported manures.

Collection of this information is a detailed process, but for a farmer who has already been through a financial benchmarking exercise, some of the relevant data is already there, so it is less arduous than starting from scratch.

CAFRE currently uses Scotland’s Rural College (SRUC) Agrecalc model to estimate the carbon footprint, as it is able to measure emissions across the whole farm, not just from a single enterprise.

Once the results are verified, each farmer receives an individual feedback report highlighting the emissions for their farm and a summary of where they originated

Farmers who are part of CAFRE’s Environmental business development groups (BDG) are also able to carbon benchmark, while dairy BDG members, who already financially benchmark, will be offered carbon audits in 2022.


As each GHG has a different global warming potential (nitrous oxide is up to x300 more potent than carbon dioxide), all GHG emissions must be converted into CO2 equivalents (CO2 e) so they can be compared.

The results on dairy farms are normally expressed as CO2 e per kg of fat (F) and protein (P) corrected milk.

Shown in Table 1 is the average milk yield, feed rate and carbon footprint across the Dairylink farms in 2020.

Milk production across the project farms ranged from 6,340l to 9,691l per cow per year, while feed rates ranged from 0.21kg up to 0.38kg per litre.

The average carbon footprint recorded across the farms was estimated to be 1.45kg CO2 e/ kg F+P corrected milk.

These figures are similar to other farms that have submitted data to CAFRE.

The results also revealed where most of the emissions originated from (Figure 1).

For example, methane production arising from the animal through enteric fermentation accounted for 38% of average emissions across the project farms. Manure management, fertiliser and feed also contributed significantly.

Fuel and electricity, on average, accounted for just 4.7 % emissions.


While farms are a source of emissions for GHG, there are a range of procedures and technologies which can be adopted to mitigate or reduce the production of these gases.

In reality, much of this comes down to good management, and making the most efficient use of resources on each farm.

Some of the areas that the project farms have focused on over the last three years will help them further reduce emissions in the longer term. For example:

  • Soil health and fertilisers: by improving levels of soil fertility across all the farms, any nutrients applied will be used more effectively. In addition, both John Oliver and Frank Goodman have used protected urea which results in significantly lower nitrous oxide emissions compared to straight urea or CAN.
  • Manure management: other farmers such as James Martin and James King are planning to implement low-emission slurry spreading techniques (LESS) which will help to make better use of any applied manures.
  • Feed efficiency: measuring grass and making better use of grazed and conserved forage has helped to reduce concentrate feed rates.
  • Replacements: the efforts that Richard Marshall and Stephen Wallace have made to ensure their heifer replacements calve down at two years of age will also help to reduce carbon emissions per kg of milk.
  • As science around emission reduction evolves, other measures will emerge but, in the meantime, there is still lots each individual farmer can do.

    With more farms undertaking carbon benchmarking, the dataset will also improve, but it is not unreasonable to expect that those farms with the lowest emissions per kg of milk will be the most efficient, and potentially the most profitable.

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