Bord Bia held an event to introduce the new lifecycle assessment model for carbon footprinting on Irish dairy farms, as part of the Sustainable Dairy Assurance Scheme (SDAS).
Bord Bia working in collaboration with Teagasc and the Irish Cattle Breeding Federation (ICBF), has made changes to the routine carbon footprinting of dairy farms conducted through the SDAS.
Mick Houlihan agri sustainability manager with Bord Bia gave a introduction to the new calculations, which will use more accurate input data and take into account recent updates to the Dairy Carbon Footprint Model developed by Teagasc.
This will improve the accuracy of the greenhouse gas (GHG) emissions and carbon footprint figures reported for all dairy farms participating in the SDAS. The new calculations will go live next week.
Changes to carbon footprinting figures in SDAS
Jonathan Herron a researcher from Teagasc outlined some of the changes to the calculations and the impact that these changes have on current emissions from farms.
Herron explained that the current figures (Version 3) were based on international default figures from the Intergovernmental Panel on Climate Change (IPCC) from 2006.
These figures were used because they were the only figures available at the time. Because farms have a wide range of factors that contribute towards emissions, it is not possible to calculate figures for every farm.
Based on this, the figures are calculated based on activity; these include animal numbers and activity data from SDAS.
From these figures, emissions can be calculated for farms, based on an Irish grass-based system, rather than standard international figures, which improves the accuracy of the model.
Moving from Version 3 to Version 4, results in improving accuracy through quantified emission factors, most up to data methodology and most relevant information.
Nitrous oxide from manure
Herron began by explaining the change in the figure for nitrous oxide (N2O) from manure. He stated: “Nitrous oxide from manure when cows are out grazing is a notable source of GHG emission from Irish dairy system.
“However there was no figure available that represented a grass-based system in Ireland, we had to use an international default value.
“The default figure from the IPCC was 0.2kg N2O/kg nitrogen (N) applied. That figure comes from international studies, which is not representative of what happens on Irish farms,” he added.
“Based off more recent research based on an Irish grass-based system, it determined that the figure for dung is 0.0031kg N2O/kg N applied an 84.5% reduction and 0.0118kg N2O/kg N applied a 40% reduction for urine.”
The reason why the figures are split is because urine is more susceptible to N loss compared to dung, due to the form the N is in.
“What this means for an average dairy farm in Ireland is that the emission associated with manure is reduced by 36%,” Herron continued.
Nitrous oxide from fertiliser application
Jonathon Herron explained the changes to the figures for nitrous oxide from fertiliser applications.
He stated: “The default figure from the IPCC was 0.01kg N2O/kg N applied and did not take into account the type of fertiliser applied or the climatic conditions.
“The research found that CAN actually produced 0.0149kg N2O/kg N applied, a 49% increase.
“While the figures for urea and protected urea were 0.0025kg N2O/kg N applied and 0.004kg N2O/kg N applied respectively, with urea having a 75% reduction and protected urea having a 60% reduction compared to the default figure from the IPCC.
“The reason for the difference between urea and protected urea behind is when you spread urea, you get ammonia loss, so there will be less N available to be lost in the next stage as nitrous oxide.
“Protect urea – you do not have that loss, so more N going to next stage,” he continued.
“Fertiliser production figures have also been updated. The Version 3 figures were from the 1990s; that technology has come a long way since then.
“From the new model, emission from CAN fertiliser before it enters your farm is 51% lower while urea is 25% lower.”
What does this means for farmers? “Based of the Version 4 figures, farms will have an average reduction in fertiliser production and application emission of 16%,” according to Herron.
“The new changes will also mean that farmers will be rewarded for the type of fertiliser they are using.”
Methane from dairy cattle
Lastly Herron looked at methane from dairy cows. He explained that methane is calculated based on the energy requirement of the cow to produce milk, pregnancy, maintenance and change in live weight.
The Teagasc representative stated that a proportion of that energy consumed will be lost to methane, the Version 3 figure was 6.5%.
“It is now 6.3% based on the international recommended value and is somewhat representative of a grass-based system,” he told the webinar.
“The figure for methane has increased by 7%, this is because Version 3 did not take into account, that as cows go through their lactation there will be changes in body weight.
“This is now accounted for at 35kg/lactation and the average cow live weight has increased to 535kg to be consistent with national inventory.
“A knock-on effect of this is that figure for heifer live weight has increased.”
Other modification included in the model includes manure management such as how long slurry is stored for on the farm, and the application method of slurry on the farm.
What does this mean for farmers?
Giving an overview of the impact that this has on dairy farms in the SDAS, Herron stated: “Previously the average in Ireland was 1.13kg CO2 equivalent (CO2e)/kg fat and protein corrected milk (FPCM), with the majority coming from methane, followed by manure at grass and fertiliser.
“What we are seeing now is yes methane has increased by 7%, however there is significant reduction is emission associated with manure and the application and production of fertiliser.
“Which brings the average Irish dairy farm figure down 0.99kg CO2e/kg FPCM. The change in the calculation sees emissions reduced on farms by 12%.
“What is important to state is that reduction is nothing to do with the farmer, the farm system is the exact same; no mitigation measures have been implemented.
“The only thing that has changed is the way it is calculated, so you cannot give farmers a reward based on that.”
The Teagasc researcher added that the research in ongoing and the figures may change again in the future.
“In the future we could go down further or increase, but we have replaced assumptions with data,” he concluded.