Agriculture & greenhouse gases

Farming creates methane and nitrous oxide gases. These gases account for around half of New Zealand's total greenhouse gas emissions. MPI puts a lot of work into researching ways to reduce these emissions.


Farming and greenhouse gases

Earth's climate has always warmed and cooled over time and will continue to do so. The speed and extent to which it does depends on both natural processes and human activities.

The greenhouse effect

Greenhouse gases accumulate within our atmosphere and are prevented from leaving the planet thanks to the greenhouse effect. Without enough of these gases, Earth would be a very cold place. If we have too much of them, however, the world becomes much warmer.

Since the Industrial Revolution, human activities have increased the rate at which these gases have gone into the atmosphere. These gases are affecting our climate by causing global temperatures to rise.

Rising temperatures affect global weather patterns – potentially causing increased frequency and severity of:

  • droughts
  • floods
  • storms
  • unusually warm and unusually cold seasons.

Changes to heat and moisture levels also affect how, when and where plants grow.

Carbon dioxide, methane & nitrous oxide

Some of the major greenhouse gases are carbon dioxide, methane and nitrous oxide.

Carbon dioxide

Carbon dioxide is produced in the extraction, production and use of fossil fuels – such as petrol and coal.

Methane

Methane is produced by ruminant animals (animals that have 4 parts to their stomach). Ruminant animals re-chew previously swallowed food – a process known as "chewing their cud". Cows, sheep, goats and deer are all ruminants.

Chewed food ferments in one part of a ruminant's stomach – known as the rumen. When it's regurgitated to be re-chewed, the animal burps. This is how most of the methane ruminant animals produce is released into the atmosphere. Cows usually spend between 3 and 6 hours each day chewing their cud.

Nitrous oxide

Nitrous oxide gas commonly comes from nitrogen fertiliser, urine and dung. Nitrogen fertiliser is used in both dairy and crop farming. The amount of nitrogen fertiliser used in New Zealand has increased by about 10 times since 1985 and doubled since the mid-1990s. This is a result of the increasing role the agricultural sector plays in New Zealand's economy.

All forms of animal waste produce both methane and nitrous oxide gases.

Improving our processes

MPI funds and leads a wide variety of research programmes which aim to increase our understanding of greenhouse gas generation and processes for mitigating it.

Reducing greenhouse gas emissions on farms

Our farmers are among the most productive and efficient in the world. Over the past 20 years, they have improved the emissions efficiency of production by about 1% a year. They have done this by improving:

  • feed and nutrition
  • animal genetics
  • pasture management
  • animal health.

Although total agricultural emissions have grown by 15% since 1990, they would have increased by more than 40% if it wasn’t for the efforts of our farmers.

More can be done

Farmers can continue to improve their emissions efficiency through a number of means, including:

  • establishing new forests to off-set emissions – known as creating "carbon sinks"
  • using fertiliser more efficiently.

Options that reduce biological emissions without reducing the number of animals on farms are still fairly limited and MPI is committed to finding ways to expand them. Both the government and the sector have established research and development programmes dedicated to this aim.

Research and development continues

Every year, we invest around $20 million in the research and development of ways to reduce biological emissions from agriculture – such as the New Zealand Agricultural Greenhouse Gas Research Centre. And it's paying off.

In early-2015, our scientists announced they'd identified animal-safe compounds that can significantly reduce methane emissions from sheep and cattle. Later that year, they showed that global solutions to reduce methane emissions from ruminant animals are feasible because the rumen microbes causing emissions are similar globally.

These discoveries are big steps in the right direction. However, much more work is required before we can turn these scientists' discoveries into safe and reliable on-farm options.

Find out more

Who to contact

If you have questions about farming and the ETS, email info@mpi.govt.nz.

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