Managing GHG emissions


4 min read

Greenhouse gas numbers Managing emissions now Managing fertiliser and feed Manage total feed eaten Improve animal health Improve effluent management On-farm vegetation What DairyNZ is doing What others are doing Additional resources

Reducing biological greenhouse gas emissions on your farm is achievable, and many of the solutions have co-benefits, such as increased farm system efficiency and improvements to water quality, animal health and profitability. Below are some practical options to consider for your farming system.

Climate change is an increasing focus worldwide. Dairy companies, banks and other institutions both in New Zealand and overseas are setting scope 3 targets that address emissions behind the farm gate. These targets are in addition to the Government’s intentions to manage and reduce agricultural emissions in the future, which may include pricing emissions. More information on scope 3 emissions targets is available here.

Farmers will be expected to understand their farm emissions, and individual organisations are outlining how their scope 3 target will impact farmers. Each organisation may have a different approach and it is important you work with them directly to understand their requirements.

There are several options available now that you can consider for managing your farms emissions. DairyNZ and others are researching solutions that will help farmers continue to reduce emissions and improve farm performance in the future.

Understanding your greenhouse gas numbers

The first step is finding out what your farm’s greenhouse gas (GHG) emissions are and where they come from.

Most dairy companies will provide your farm’s GHG numbers, along with other environmental information, via an annual report. Another option to understand your emissions is to look at your Overseer or Farmax file.

Most dairy company reports will show a farm’s emissions as two numbers:

  1. Biological emissions per hectare: this figure, multiplied by the total effective hectares for a farm, gives the total or ‘absolute’ emissions number for a farm. This is likely to be the focus for any future government pricing system for agricultural emissions.
  2. Emissions per kg/MS: this is a farm’s emissions intensity number and is the focus for dairy company and bank ‘Scope 3’ targets.

For more information on the different numbers, see our Climate Overview page.

There are three main drivers of on-farm biological emissions:

  1. Dry matter intake: this drives biological methane emissions (21.6g of methane is produced per kg DM eaten) and has a strong correlation with nitrous oxide emissions.
  2. Protein (nitrogen) content of the feed: this drives nitrous oxide emissions.
  3. Amount of nitrogen fertiliser used: this drives nitrous oxide emissions.

For more information on the sources of emissions on a farm, see our On-farm emissions page.

Once you understand your farm’s emissions profile, you can consider where and how you can make changes to manage and reduce your emissions.

Managing on-farm emissions now

There are five actions available to farmers now that can help reduce emissions. These actions will also help improve farm system efficiency and may have co-benefits for freshwater outcomes and biodiversity.

  • Manage fertiliser and feed use to improve the efficiency of production.
  • Manage the total feed eaten on the farm.
  • Improve animal health management to increase on-farm efficiency.
  • Improve the management of on-farm effluent.
  • Look at opportunities to plant or restore on-farm vegetation.

Manage fertiliser and feed use to improve the efficiency of production

Managing fertiliser and feed use can help minimise loss to waterways and improve the efficiency of pasture and crop rotation. There is a strong link between reducing nitrogen loss and biological greenhouse gas emissions. Making these efficiency improvements can also reduce emissions on-farm if the total feed eaten is decreased or production is increased with the same inputs.

What you can do on farm:

  • Prepare an annual nutrient budget with your trusted farm consultant or fertiliser representative.
  • Minimise surplus nitrogen through reduced use of nitrogen fertiliser and supplementary feed.
  • Use urease-coated fertilisers which reduce losses of ammonia from urea use and maximise the nitrogen available for plant uptake. This means less nitrogen needs to be used and less nitrous oxide is emitted.
  • Manage the timing and placement of nitrogen fertiliser to reduce the amount of nitrogen applied while still increasing pasture growth.
  • Consider the use of plantain in your pasture sward. Research has shown it can help reduce nitrogen surplus.
  • Undertake regular testing to ensure correct soil fertility.
  • Monitor and maintain soil phosphorus levels below or within the target ranges for the soil-type and crop.
  • Match feed demand with pasture growth and utilisation. Balancing pasture growth and utilisation is key to optimising stocking rates that result in the same or higher profit with lower inputs.
  • Manage pasture and crop husbandry to optimise production through fertility, rotation, and inputs, while minimising damage from compaction, diseases, and pests.
  • Store fertiliser in a contained system to minimise losses and calibrate and maintain fertiliser spreading equipment.

Manage the total amount of feed eaten on-farm

The total amount of feed eaten on a farm is a major driver of emissions. For every additional kg of total feed eaten per hectare, total methane emissions increase proportionally.

What you can do on farm:

  • Evaluate your farm’s stocking rate, individual animal performance and the need for supplementary feed in your farm system.
  • Identify and cull less productive stock early to reduce demand later in the season.
  • Reduce wastage rates from unplanned losses so replacement rates can be optimised and total feed eaten reduced.
  • Use genetic selection over time to increase animal performance and decrease livestock maintenance requirements. This is a long-term decision and will only yield a small response over time.

For more on the options that might be available in the future, check out DairyNZ’s Less Methane project.

Improve animal health management to increase on-farm efficiency

Increasing the performance of animals while reducing the need for replacements will lead to on-farm efficiencies and fewer greenhouse gas emissions. This is mainly through producing the same or more product with fewer animals.

What you can do on farm:

  • Improving nutrition through increasing feed efficiency, the ME of feed, and farm-grown feed will reduce total feed eaten and therefore emissions.
  • Improved animal health through managing animal issues such as lameness, Johne's disease, metabolic issues, and other animal sickness will reduce wastage and improve on-farm efficiencies.
  • Focus on reduced mastitis and somatic cell counts to improve production, reduce wastage, and increase on-farm efficiency.
  • Improving the reproduction efficiency of the herd will minimise wastage from later calving cows and not-in-calf cows. This can be done by focusing on the 6-week in-calf rate and the ‘Fertility Focus Report’, and will ultimately lead to reduced replacement rates and influence the timing of culling decisions.

Improve the management of livestock effluent

Effluent can be a source of nutrient loss, contaminants entering waterways and greenhouse gas emissions. However, it can also be a valuable resource that, when managed well, increases pasture production, and reduces fertiliser costs.

What you can do on farm:

  • Consider developing an effluent management plan. This is a handy tool for bringing together all effluent needs on a farm, including regional rule requirements, location of waterways, buffer exclusions, and system maintenance schedules.
  • Spread effluent during appropriate soil conditions and at low application rates to minimise nutrient loading, match plant requirements, and minimise ponding and runoff to waterways.
    • This will also help reduce the N-surplus and therefore the nitrous oxide emitted from the soil.
  • Test effluent regularly so that nutrient concentrations are known, and application rates can be adjusted.
  • Use all effluent applications as a substitute for fertiliser applications, enabling reduced fertiliser on effluent application areas.
  • Practice deferred effluent irrigation and store effluent during inappropriate soil conditions.
    • Avoid storing effluent in anaerobic conditions as this will increase methane emitted. Options to reduce this include stirring, covering, or adding treatments like polyferric sulphate.
  • Ensure careful management of effluent from housing and stand-off pads due to the volume created by both liquids and solids. Ensure that it doesn’t lead to increased risk of nutrient loss and increased emissions from application and storage.

Look at opportunities to plant or restore on-farm vegetation

Planting or restoring indigenous and exotic vegetation on farm can help improve erosion control, waterways, biodiversity, livestock shade and shelter, and soil health.

  • Some types of vegetation may be eligible for earning carbon credits through the Emissoins Trading Scheme (ETS), provided they meet certain requirements. New plantings may also result in reduced on-farm emissions if there is land use change.
  • Look at opportunities to protect and plant riparian areas and restore natural wetlands. This improves waterways by filtering contaminants, preventing weeds, lowering temperatures, providing habitat, and reducing the impact of flooding.
  • It can be helpful to have a planting plan for your farm which identifies the priority sites for planting.
    • Your regional council or local catchment group may offer support for some types of on-farm planting and restoration.

What might be available in the future?

There are a range of actions you can take now to reduce your farm’s emissions. Further options and solutions are being researched.

Technological and farm system solutions to reducing on-farm emissions, such as inhibitors, will be essential in assisting farmers to meet their emissions reductions goals. Research is underway to develop technological solutions and efficiency gains to help maintain New Zealand's position as one of the most emissions-efficient milk producers in the world.

What is DairyNZ doing?

DairyNZ has a range of research underway to assist farmers in reducing their emissions.

The Less-Methane team at DairyNZ are working on several viable solutions to reduce methane emissions on New Zealand farms.

The DairyNZ Plantain programme aims to substantially reduce nitrogen lost to freshwater and greenhouse gas produced from farms.

The Southern Dairy Hub is looking at a range of issues that affect southern dairy farmers, including looking at the intricacies and differences of emissions profiles between farms and how best to optimise operations for reducing emissions.

What are others doing?

Alongside DairyNZ, other research and industry organisations are exploring new technologies and practices for reducing biological emissions, e.g. inhibitors, vaccines, low-emissions livestock and feeds and more. For more information see:

  • AgriZero: a world-first partnership between New Zealand agribusinesses and the government to accelerate the availability of tools and technology to reduce methane and nitrous oxide emissions on New Zealand farms.
  • New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC): coordinates much of the Government-funded research in New Zealand into agricultural greenhouse gas emissions, including methane, nitrous oxide, soil carbon and future farm systems, and a dedicated Māori research programme.
  • Ag Matters: a website managed by the NZAGRC with information for farmers on actions to reduce agricultural emissions both now and in the future.
Last updated: Dec 2023

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