Understanding how we calculate your emissions

If you’ve looked at your farm’s greenhouse gas emissions footprint and wondered how that number is worked out, you’re not alone.

While the final number might seem simple, it’s built using a combination of your farm data, New Zealand science, and industry information to create a fair and consistent picture of emissions efficiency on your farm.
 

It starts with your farm dairy records

The foundation of your emissions calculation is the information you provide through your Farm Dairy Records (FDRs) and milk collections. This includes data such as:

• Monthly stock numbers
• Feed purchased and fed
• Fertiliser use
• Effluent management
• Crops grown and fed
• Numbers of stock wintered or reared off farm
• Milk production

This farm-specific information is combined with recognised industry data and scientific research through the Ag:LCA (Agricultural Life Cycle Assessment) model, developed by the Bioeconomy Science Institute specifically for New Zealand’s pasture-based farming systems.

Understanding the three greenhouse gases

Your emissions footprint is made up of three key greenhouse gases:

• Methane (CH4): mainly produced when cows digest feed and from effluent storage.
• Nitrous Oxide (N2O): released from urine and dung deposited on pasture, as well as nitrogen fertiliser applied to soils.
• Carbon Dioxide (CO2): associated with producing and transporting feed and fertiliser, along with smaller contributions from fuel, electricity and other farm inputs.

How the model works

Rather than measuring emissions directly, the model estimates emissions by first calculating how much feed your animals consume. Using information such as stock numbers, liveweight, milk production and feed types, an energy model estimates the amount of feed required to maintain your herd and produce milk. That feed intake is then used to calculate methane emissions and the nitrogen excreted by animals, which helps determine nitrous oxide emissions.

The model also considers:

• Imported feed volumes and feed quality
• Fertiliser type
• Effluent systems
• Crop residues
• Electricity and fuel use
• Off-platform grazing and support land emissions

Where farm-specific information is unavailable, credible New Zealand industry datasets are used to fill gaps.

Why two farms can have different results

Every farm system is different. Factors such as cow liveweight, feed use, fertiliser inputs and milk production all influence the final result. Your footprint is measured on an intensity basis, that is, as emissions per unit of milk produced (per tonne of Fat and Protein Corrected Milk (FPCM)). This approach recognises that productivity changes occur on farm from season to season, while still driving lower emissions per tonne of output. Producing the same milk with fewer resources generally improves emissions efficiency.
 

More farm data, fewer assumptions

For the 2025/26 season, the model has been updated to better reflect what’s actually happening on farm. Where possible, calculations now use actual farm information such as monthly stock records and liveweight data, rather than broader industry assumptions. This means emissions results are becoming increasingly representative of each individual farming system.
 

It’s about understanding opportunities

Your emissions number is not simply a measure of total emissions – it’s a tool to help understand what’s driving emissions on your farm and where efficiencies may already exist.

By combining farm records, industry science and ongoing model improvements, Fonterra aims to provide farmers with a robust and transparent estimate of emissions that reflects the realities of New Zealand dairy farming.
 

Want to learn more?

Visit the Farm Source Farm Emissions Made Simple page or talk with your Sustainable Dairying Advisor for more information about your farm’s emissions profile.