Know your numbers

How to calculate your farm’s greenhouse gas emissions and make a plan to reduce them.

Knowing what your farm’s greenhouse gas emissions are and where they come from is the first step towards reducing them. All farmers and growers in New Zealand will have to know their greenhouse gas numbers by December 2022 and have a written plan in place for managing them by December 2024.

Why do I need to know my farm’s greenhouse gas numbers?

If you have a farm over 80 hectares, or a dairy farm with a milk supply number, or a cattle feedlot as defined in the National Environmental Standards for Freshwater*, you will need to meet the following requirements: 

  • By December 2022, you will need to know your farm's annual methane and nitrous oxide emissions - your greenhouse gas 'numbers'
  • By January 2025, you will need to have a written plan in place for measuring and managing those emissions.  

Five Jersey cows in stalls in milking shed

These requirements are included in the climate change legislation and will be delivered through 'He Waka Eke Noa', a five-year industry-Government-Māori partnership set up in late 2019 to support farmers to measure, manage and reduce agricultural greenhouse gas emissions.

A key focus for He Waka Eke Noa is to develop a pricing system for on-farm emissions that will apply from January 2025. The alternative is that agricultural greenhouse gas emissions come into the Emissions Trading Scheme (ETS) at the processor level. This may happen if good progress is not made in He Waka Eke Noa and these milestones aren't met.

The sooner you find out your farm's greenhouse gas numbers, the sooner you can start to understand where those emissions come from and what actions might be possible to manage or reduce them on your farm. This will set you in good stead for meeting the legislated milestones and participating in the future pricing system. 

* NOTE: It is likely that a different definition of a farm will be used for the pricing system that may encompass smaller farms.

What tools can I use?

There are several different ways that you can find out your farm's greenhouse gas numbers:

  1. Use a tool or calculator to do it yourself
  2. Ask your farm advisor which tool/s they use and what services they can offer you in this area
  3. Ask your processing company or industry organisation for advice. Some are moving into this area, including providing these numbers for their farmers (see below). 

Tools and calculators

A variety of tools for estimating agricultural greenhouse gas emissions at the farm level are available. These range in complexity and cost from simple, quick and freely available calculators to more detailed quantitative tools that might also require assistance from a farm advisor in order to access and/or interpret the results. Some of these tools are also specific to a particular farm type. 

A process is underway in He Waka Eke Noa to assess the suitability of different tools for calculating a farm's greenhouse gas numbers. So far, 11 have been assessed (in alphabetical order): 

  • Alltech has a proprietary carbon footprint service 'E-CO2' for businesses.
  • Beef + Lamb NZ has developed a GHG Calculator - a free online tool for farmers to measure and report on-farm greenhouse gas emissions and sequestration, reflecting the individual farm's livestock and production systems.
  • E2M is an enviro-economic model operated by Grazing Systems Limited that is based on a linear-programming platform and can model whole farm systems including greenhouse gas emissions.
  • Farmax is a decision-support tool for pastoral farmers that incorporates productivity and profitability data and now includes a greenhouse gas component. 
  • Fonterra is using the Agricultural Inventory Model (AIM) to provide estimates of on-farm emissions for all its suppliers. AIM underpins the New Zealand Greenhouse Gas Inventory. 
  • Horticulture New Zealand has a nitrous oxide emissions spreadsheet developed by (and available from) MPI for its growers.
  • The Ministry for the Environment has a spreadsheet calculator for New Zealand businesses, including farms, to work out their greenhouse gas numbers.
  • MyImprint is a proprietary model, based on the New Zealand greenhouse gas inventory. It can model farms that have sheep, beef, deer and dairy cattle and includes forestry sequestration.
  • OverseerFM is a software platform for modelling nutrient flows through a farm and includes a greenhouse gas component. 
  • ProductionWise is a crop record-keeping and decision support tool developed by the Foundation for Arable Research (FAR) that now generates greenhouse gas numbers for arable systems. 
  • Toitū Envirocare offers a tool that builds on greenhouse gas data from OverseerFM to provide an ISO certifiable carbon footprint of a farm. 

You can find out more about these tools in two independent reports prepared by AgFirst for He Waka Eke Noa. As more tools are available, they will also be assessed and the findings made public. 

NOTE: The tools listed on this page have been endorsed for use in meeting the legislated He Waka Eke Noa milestones. However, they may not be the tool/s used in the pricing and reporting that will apply from 2025. More will be known on that as the work is completed. 

What data do I need?

Female farm worker drenching lambs in the yardsAt a basic level, annually, you will need to know:

  • Livestock numbers by stock type/s, either using monthly values or (for simple tools) a weighted annual average 
  • Amount of synthetic nitrogen fertiliser applied

Additional data that can support a more detailed estimation of greenhouse gas numbers includes: 

  • Farm size - total and effective areas 
  • Livestock class, age, number and movements
  • Production data such as total kg milk solids, liveweight or crop yield, and percentage share of revenue 
  • Purchased feed
  • Nitrogen fertiliser or lime applications, including product type, rate and timing 

NOTE: Different tools will give you different numbers. This is because the models that sit underneath them rely on different values, depending on their complexity. For example, while simpler tools are relatively quick to complete, they rely on national/international default values for estimating methane and nitrous oxide. This typically results in a less accurate farm-scale greenhouse gas footprint, but is useful for generating a quick estimate. 

A more detailed tool can take longer to complete and will require more detailed data (e.g. feed types and N content, dry matter intake, metabolisable energy, animal liveweights, replacement rates etc), but will better reflect farm-scale emissions (and reductions). 

How will greenhouse gas emissions be incorporated into farm plans?

Mackenzie farm, CanterburyFarm plans enable the unique nature of a farm to be captured and are an important tool to help farmers manage their land in an environmentally and financially sustainable way. Many farmers already have a farm plan in place.

The He Waka Eke Noa partnership has agreed that a farm planning approach is essential for the sector to achieve a net reduction in agricultural greenhouse gas emissions. By 2025, farmers and growers will need to have a written plan in place to measure and manage their greenhouse gas emissions. 

To keep things simple, the intent is to add a greenhouse gas 'module' to existing farm plans, such as those required by regional councils, processor programmes, fertiliser company plans and irrigation scheme programmes.  

This greenhouse gas module will include: 

  1. Knowing your farm's greenhouse gas numbers
  2. Identifying opportunities to reduce your farm's greenhouse gas emissions and capture carbon 
  3. Choosing which actions you could implement in your system
  4. Keeping records, monitoring and reviewing progress

If you are a dairy farmer: 

If you are part of Synlait Lead with Pride, Miraka Te Ara Miraka, Tatou 360 or Fonterra Tiaki programmes, these will align with the He Waka Eke Noa greenhouse gas module requirements from 2021. 

Other dairy company programmes will be modified to include a greenhouse gas module prior to 2025. 

If you are a grower: 

If you are an arable grower, the Foundation for Arable Research Farm Environment Plan template should be used. 

If you are a fruit or vegetable grower, the Good Agricultural Practice (GAP) Environmental Management System (EMS) add-on can be used for greenhouse gas module requirements.  

If you are a sheep, beef or deer farmer: 

Beef + Lamb NZ has launched its new farm plan template, which includes a climate change module. Deer farmers may also wish to talk to Deer Industry New Zealand

Processing companies are also looking to start rolling out New Zealand Farm Assurance Programme Plus (NZFAP Plus) in 2021, which should also be able to be used to meet the greenhouse gas module requirements. 

If you run a multi-sector farming enterprise: 

Many farmers and growers in New Zealand are multi-sector, growing and supplying crops and livestock for different purposes and to different processors. Some have multiple farms that are spread across one or more regions. 

You can decide how a greenhouse gas module for your farm plan is best prepared and reported on. Some of the farm plan delivery programmes listed above are cross-sector and can account for multiple farms. If you have a focus in one sector, e.g. sheep and beef, you can choose one of these programmes to complete your greenhouse gas module. 

Whichever pathway you chose, please tell the different farm plan delivery programmes that you belong to how you will complete your greenhouse gas module. This will help with reporting.

If you are not in a farm plan delivery programme:

You can talk to the industry organisation that best suits your farming system, or use the information included in the He Waka Eke Noa Farm Planning Guidance document. 

What happens if I don't do anything?

If the He Waka Eke Noa milestones aren't met, it's possible that the programme won't be considered successful. This means agriculture could be brought into the ETS at the processor level instead.