Reducing emissions from food production is essential to tackle climate change and meet Government targets.

Farming practices play a key role in this. At last week’s Alltech Ireland Environmental Forum, Emma Swan and Dr Stephen Ross went through areas that can be improved on Irish dairy farms.

By implementing these changes, the carbon footprint on Irish dairy farms could be significantly reduced.

Emma described how 70% of emissions from a litre of milk come from inside the farm gate, but going back to basics can reduce those emissions.

Calculating the carbon footprint

The carbon footprint can be calculated through a lifecycle assessment (LCA). This takes into account the environmental impacts of inputs, processes and outputs on farms right up to the products leaving the farm.

The carbon footprint includes the levels of carbon dioxide, methane and nitrous oxide emitted per unit of output on the farm.

On dairy farms, the carbon footprint is expressed as the number of kilogrammes of carbon dioxide equivalents (this includes carbon dioxide, methane and nitrous oxide) produced per kilogramme of fat and protein corrected milk (kg CO2e/kgFPCM).

Stephen noted the greatest contributor to the LCA is the animal: “The opportunity for the greatest mitigation is through improvements in animal health, productivity and more efficient use of feed.”

Any small improvement you can make on farm will have a knock-on effect on other things in the lifecycle.

Dairy emissions

Using data from the ICBF and the National Farm Survey, Alltech placed the emissions intensity of the average Irish dairy farm at 1.14 kgCO2e/kgFPCM. This is based on:

  • A herd size of 86 cows.
  • Farm size of 59ha.
  • 417kg MS/cow.
  • 4.1% fat and 3.5% protein content.
  • 184kg N/ha.
  • 1,176kg of ration/cow.
  • Carbon footprint of 1.14kgCO2e/kgFPCM.
  • Stephen outlined how this carbon footprint can be reduced.

    Grass utilisation

    Stephen said the current average grass utilisation figure on Irish dairy farms is 7.8t DM/ha. If this was to increase to 9t DM/ha over the next five years, the carbon footprint could be reduced to 1.12kgCO2e/kgFPCM. That’s a reduction in emissions of 1.8%.

    Stephen said this can be achieved with improved grassland management, soil fertility and reseeding. Emma noted that farmers on Alltech’s InTouch system who are using PastureBase produced 10t DM/ha in 2019 and 11.5t DM/ha in 2020, while also increasing milk solids by 20kg with no extra concentrates.

    Forage quality

    Alltech placed the average forage quality at 0.86UFL and 12% crude protein. Stephen noted that if this was to increase to 0.93 UFL and 13% crude protein, the carbon footprint could be reduced by 4.9% to 1.08kgCO2e/kgFPCM.

    “After taking the winter dry period into account, if you were feeding silage for 2.5 months at the beginning of the season, this equates to an extra 135 litres or 10.5kg MS/cow. The increased protein in the silage would also allow us to reduce the level of soya in the typical concentrate as fed and this would reduce the supplementary protein in the concentrate by approximately 1%,” he stated.

    Fertiliser use

    Fertiliser is another area where reductions need to be made. Alltech outlined a reduction target of 1.5%/year, moving from 184kg N/ha to 170kg N/ha.

    Ammonia emissions can be dramatically reduced through the use of protected urea. Nitrous oxide emissions can also be reduced by a switch to protected urea from CAN.

    This reduction in fertiliser use would equate to a decrease of 5.5% in emissions intensity to 1.08kgCO2e/kgFPCM.

    More efficient milk production

    Improving the efficiency of milk production through nutrition, feed efficiency and genetics can dramatically reduce carbon emissions, while also increasing milk solids by 3%/year to 487kg MS/cow. Precision feeding, a plan to ensure cows are being fed at the right time to capitalise production and feeding the correct minerals could result in a potential drop of 9.9% in emissions to 1.03kgCO2e/kgFPCM.

    Possible 20% reduction in carbon footprint of Irish dairy herds

    Taking all of these factors into account and accounting for overlaps, Alltech estimated a possible reduction in the carbon footprint of 20% over five years, moving from 1.14kgCO2e/kgFPCM to 0.92kgCO2e/kgFPCM. This is outlined in Table 1.

    Feeds footprinting tool

    Alltech has developed a feeds footprinting tool which reformulates rations based on their environmental impact.

    Emma described differences between two rations, one of which was lower in soya and beet pulp than the other. The results of this can be seen in Table 2. The global warming potential of the reformulated ration dropped by 51% and reduced the cost of the feed by €2/t.