Reducing emissions in dairy farms
Global warming is caused by greenhouse gases (GHGs) released through human activities accumulating in the atmosphere and forming an insulating layer. The gases released from agricultural activities are primarily carbon dioxide (CO2), methane (CH4) and nitrous oxide (NO2).
Agriculture currently accounts for approximately 18% of Australia’s total greenhouse gas emissions. In 2023, dairy represented 29% of Victorian agricultural emissions, 5% of the state's total GHG emissions.
Dairy farms each have a different profile of emissions, but the average breakdown in 2023 was:
- 68% CH4 from cattle and effluent
- 13% upstream emissions from purchased inputs including fodder, concentrates and fertiliser
- 11% NO2 from fertiliser, manure and urine
- 6% CO2 from on-farm electricity use
- 2% CO2 from on-farm diesel use.
Knowing how much each of the various sources of your on-farm emissions contributes to the total farm emissions. This is important to help determine where and how to invest your time and effort to reduce emissions.
The Australian Dairy Carbon Calculator can help to determine your farm's emissions. It estimates your emissions using data such as herd numbers, milk production, energy use and feed purchases, as well as state and national-based factors. This means that the quality of the result is only as good as the quality of the data used. Contact the Agriculture Victoria Dairy Services team, or your consultant, if you need help to complete an estimate.
Case studies are now available which share the story of dairy farmers who took part in the Agriculture Victoria On-Farm Emissions Action Planning Pilot.
Reducing your emissions
Once you know where the emissions on your farm are coming from, you can address the sources.
There are two approaches to monitoring emissions reduction in agriculture:
- Total or absolute emissions - directly reducing the total emissions your farm produces over a certain time period; or
- Emissions Intensity (EI)- reducing emissions per unit of output. On dairy farms, this is expressed as carbon dioxide equivalent (CO2-e) per kg fat and protein corrected milk (FPCM) or milk solids (MS).
Absolute emissions are driven by overall farm and herd size, so emissions intensity is often used for benchmarking and comparison between producers within a supply chain. It is also a good way to express and compare emissions efficiency in terms of the product, which is helpful for supply chains and consumers. EI is a useful metric, and all industries are planning to improve their absolute emissions performance and EI each decade. The ultimate focus is on reducing total absolute emissions that enter the atmosphere, as this drives climate change risks.
These different measures mean it is important to define and understand your goals before taking major action on emissions. Some methods to reduce absolute emissions may impact productivity or other business objectives, potentially having a knock-on effect on your EI, or compromising other farm goals and benchmarks. Therefore, emissions reduction actions must be carefully matched to business goals and the circumstances of your farm.
Some actions, such as reducing power use and improving fertiliser practices, will reduce both overall emissions and intensity, as they reduce emissions without impacting overall production. Similarly, if you improve milk production per cow to the extent that you can reduce overall herd numbers while maintaining or improving production levels, you may reduce both EI and absolute emissions.
Once your emissions sources are understood, and your goals are set, actions can be taken.
Some strategies to reduce emissions from dairy include:
- Optimising nutrition to ensure that cows are producing to their potential and getting only what they need
- Timing and targeting fertiliser and effluent applications on pastures to reduce nitrogen losses
- Auditing and improving energy efficiency to reduce waste and manage bills- dairies use a lot of power, so this may be a good way to reduce costs and emissions!
- Managing effluent to minimise CH4 production from ponds, stockpiles and screened manure from mechanical separation
- Reducing purchased inputs where possible, such as increasing homegrown feed
- Implementing on-farm renewables and technologies such as batteries and thermal storage to reduce grid reliance
- Using efficient and low-emissions machinery to reduce diesel use.
The largest emissions source on most livestock enterprises, including dairy, is enteric methane produced from cows belching during digestion. There are feed additives and other technologies in development to reduce this, but many are still in development or not yet commercially practical.
Emissions sequestration
As well as reducing emissions by changing farm practices or equipment, farms can also take carbon out of the atmosphere by growing trees or changing soil management practices.
While soils can be a good way to sequester carbon, they are inherently variable carbon sink, and many dairy farms will have high soil carbon to begin with due to long-term pastures. Tree planting can be a simpler and more secure option for dairy farms, and can provide co-benefits such as stock shade and shelter, increased biodiversity, improved water quality in dams and creeks, aesthetic benefits and management of salinity issues. Agriculture Victoria has more resources on trees on farms for interested farmers.
Sequestered carbon on farms can be traded via a scheme such as the Australian Carbon Credit Units (ACCU) Scheme, which is subject to high levels of scrutiny and regulation. Registered projects can create carbon credit units, which can then either be sold to other businesses to use for offsetting their emissions. Farmers may wish to keep their carbon sequestration to balance or “inset” their own emissions, keeping all emissions and sequestration in the same supply chain. This practice of insetting benefits the whole supply chain, as it means milk produced on that farm can be accounted for as a lower-emissions product than otherwise, resulting in fewer emissions in the accounts of processors and end users of that product.
Other Resources
For more information on the above topics and emissions reduction: