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The health of our soils

Soil is vitally important to the New Zealand economy and environment. Our use of land and soil requires careful management to maintain soil health and prevent soil-related issues – including erosion, excess nutrients and contamination.

Many of our soils are prone to erosion

Erosion is probably the most critical issue affecting soil and the productivity of the land we use for farming, horticulture and forestry.

When people first arrived in New Zealand and started clearing forest, the amount of land vulnerable to erosion increased dramatically. Planting new trees has helped curb some of the worst cases, but erosion is still an issue particularly in the north and east of the North Island.

Erosion affects productivity by removing topsoil — the most nutrient-rich part of the soil. It also affects the quality of surrounding waterways through increasing sediment and nutrient run-off.

See which areas in the North Island are erosion prone – Statistics NZ website

Excess nutrients can affect the environment

When we put more nutrients on land than grasses and other plants can use, the excess nutrients can leach into groundwater and waterways. The excess nutrients can cause unwanted plants to grow and affect freshwater quality.

Soil contamination

Past use of chemicals in industry, agriculture and horticulture has left some New Zealand soils contaminated. Depending on their location, these contaminants could affect agriculture, people, water bodies and the broader environment.

Find out more

Why we need to protect soil

Soil underpins New Zealand's agriculture, horticulture and forestry and contributes to healthy ecosystems by helping to clean water, cycle nutrients, store carbon and grow plants and animals.

Creating new soil is a slow process and can take hundreds to thousands of years, which effectively makes soil a non-renewable resource in our lifetimes. Protecting soil is essential for food security and a sustainable future.

Why bother about soils – Manaaki Whenua

Protecting land and soil

MPI and other Government agencies work to protect our natural resources (including soil) through policy, management programmes, research and funding.

The future of soil management

To help us make decisions to protect our soil and land resources, MPI commissioned a report on the state of soil management in New Zealand.

A summary and the full 2015 report are available to download.

Future requirements for soil management in New Zealand – summary [PDF, 1.3 MB]

Future requirements for soil management in New Zealand – full report [PDF, 9.5 MB]

Major pressures identified

The report identified the major pressures affecting soil (and other natural resources):

  • Intensification: Especially through irrigation and addition of nutrients. Little is known about the long-term effects of irrigation on soil function. Nutrients can encourage rapid plant growth but threaten freshwater quality.
  • Land use change: This can result in erosion and sediment run-off to freshwater.
  • Legacy effects: Past deforestation and climate change – with more frequent or intense storms – are likely to increase the risk of erosion.

An action plan will be developed based around the report's recommendations – which include a national management group and strategy to set direction on soil use, policies and research.

Smart management of nutrients

OverseerFM® is a nutrient management tool owned by MPI, the Fertiliser Association of New Zealand and AgResearch Limited. The online software helps farmers and growers improve fertiliser use to optimise plant growth and minimise nutrient losses to the environment.

Read more about the Overseer model and OverseerFM®
Overseer® website

Monitoring soil contaminants

The Ministry for the Environment (MfE) and regional councils are responsible for monitoring soil contaminants. MfE's website has more information about the National Environmental Standard for monitoring soil contamination to protect human health.

Digital mapping of soils

S-map is a digital system for storing and managing soil information in New Zealand from soil types that have been mapped in detail. It currently covers 62% of productive land.

Regional councils use S-map for freshwater quality and quantity management. Farm consultants and council land management officials use it to identify soil types to help develop farm plans, dairy effluent management plans, and septic tank location guidance.

S-map data is used to improve Overseer’s estimates where it is available.  

Read more about the Overseer model and OverseerFM®

Explore the information currently available in S-map – Landcare Research website

Investment in S-Map expansion is ongoing / was carried out in 2020. S-Map is currently being expanded in Canterbury, Horizons, Otago, Taranaki, and Waikato. Discussions are in progress with other regional councils to progress work further.

Soil management programmes, funding and research

Targeted funding is available for some soil management issues. For example, MPI provides funding to landowners and regional projects to manage erosion through activities like tree planting and catchment management.

Explore all of MPI's funds that support and enhance natural resources 

Soil is important for storing carbon

Soil is recognised as important for storing carbon – providing a way to reduce greenhouse gas emissions. There is more carbon in Earth's soils than in terrestrial plants and the atmosphere combined, which means small changes in soil carbon could have big impacts on global greenhouse gas emissions.

Because it's an area of ongoing research, there are not yet any robust practices in New Zealand to sustainably increase carbon in soils over the long term. Some options may include having deep rooted plants or adding biochar – a form of organic matter charred under controlled high temperature conditions.

Find out more

Who to contact

If you have questions about the information on this page, email info@mpi.govt.nz

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