The carbon footprint on dairy farms needs to fall much faster

Since its inception, Bord Bia’s Sustainable Dairy Assurance Scheme (SDAS) has provided a focus on some of the key metrics of climate change, especially the so-called carbon footprint, or the kg amount of CO2-e per kg of fat corrected milk and protein (FCMP).

SDAS also provides an indication of the key relationships between the estimated footprint and key productivity and climate change mitigation measures on farms.

Apart from the usefulness of SDAS to dairy farmers, it’s also important information for the co-ops in their interactions with customers.

While the carbon footprint is the most widely used climate change metric in agricultural circles, it does, however, give an incomplete and potentially misleading picture when it comes to our national carbon and EU carbon targets.

These targets concern total gross emissions – that is, the footprint times the level of dairy production. It’s possible for the footprint to be declining but for overall emissions to be increasing due to an increase in production that offsets the reduction in the footprint.

Production, in turn, will be driven by cow numbers and feed and fertiliser consumption.

SDAS is not the only source of information on climate change metrics in Irish farming.

Teagasc has been using its National Farm Survey data to generate similar metrics to SDAS for several years.

Unlike SDAS, the Teagasc data is drawn from a stratified random sample of Irish farms and the data is collected from farms by a team of specialised recorders, who visit the farms about eight times per year.

Accuracy

The SDAS field staff visit farms on a much less regular basis, and thus the accuracy of the data is lower than the Teagasc information.

The Teagasc data also enables a much more comprehensive analysis of the relationship between climate metrics and farm performance, especially farm profitability.

While the Teagasc data is representative of the national dairy farm, it can’t capture the picture at the co-op level. This is the main strength of SDAS and the co-ops intensively use SDAS in their interactions with their customers.

According to SDAS, the national dairy sector’s carbon footprint has fallen from 1.02kg of CO2-e per kg of FCMP in 2019 to 0.97kg in 2024.

This is a decline of about 1% per year and the trend is in line with the preceding five years. However, over the same period, the gross level of emissions, as recorded by SDAS, increased by around 2% each year.

And it should be remembered that emissions last year were substantially below the previous year due to the impact of the war in Ukraine on fertiliser prices and consumption.

Thus while the carbon footprint has been falling, the overall level of emissions has been increasing.

The main production drivers revealed by SDAS were an increase in cow numbers (+11%) and milk yield (+6% solids). SDAS also indicates that there has been a significant change in fertiliser use practices on dairy farms.

Lime and protected urea

Protected urea has increased from 0% in 2020 to 32% last year and CAN has fallen from 73% to 51% over the same period. Another major positive development has been the increase in lime usage from 16% to over 30%. Over 90% of farms are reported to have completed soils tests, although the trend has been stable.

It’s not clear though how farmers utilise the tests in fertiliser planning. The consumption of chemical fertiliser N has been fairly stable at around 130kg/ha up to last year when consumption fell because of higher prices.

The use of lower-emission slurry spreading (LESS) has grown substantially from 20% of herds in 2019 to 85% last year but the application of slurry during spring has been fairly stable at around 40%.

If the divergent trends in the carbon footprint and total emissions persist, it will not be possible to meet our national and EU commitments on climate change by 2030 or in the following years.

It is clear, therefore, that we have to urgently find a mechanism to substantially reduce our carbon footprint.

Technologies that can yield dividends in the medium to long run include the use of feed additives in pasture systems and genetics.

In the short to medium term, a much increased use of protected urea will also help, as will an increase in the use of organic fertilisers.

But a “game changer” is clearly required to effect a structural change in the carbon footprint that’s substantially in excess of its 1% annual trend decline. Technologies are available in respect of manure management, for instance, that have the potential to reduce the carbon footprint with full adoption by up to 9%.

The challenge is to devise policies to encourage farmers to utilise these and other technologies which will deliver direct benefits to society, but not to the individual farmer.