Measuring soil carbon

The Ministry for the Environment reports carbon stock changes in soils as part of tracking New Zealand’s greenhouse gas emissions from land use. This page explains the role of soil organic carbon and how it is monitored.

Role of soil carbon

Soil is an important reservoir of carbon. Soil organic carbon is the major component of soil organic matter, which is made up of micro-organisms and decomposing plant and animal material.

A change in land use can cause the soil carbon stock to increase or decrease, especially if there is a disturbance of the top soil as in agriculture and forestry. When a land-use change decreases the soil carbon stock, carbon dioxide, a greenhouse gas, is emitted to the atmosphere. When a land-use change increases the soil carbon stock, carbon is removed from the atmosphere. 

Monitoring carbon stock changes in mineral soils

The Soil Carbon Monitoring System is a statistical model designed for estimating soil organic carbon stocks in New Zealand’s mineral soils. It follows methodology recommended by the Intergovernmental Panel on Climate Change (IPCC).

The model combines actual soil carbon data (samples collected from New Zealand soils under different land uses) with national spatial datasets of soil type, climate, land use and topography. The Ministry for the Environment uses it to:

  • derive estimates of soil organic carbon stocks for all land uses, and
  • estimate changes in soil organic carbon following changes in land use.

Measuring carbon stock changes in organic soils

Organic soils occupy a relatively small proportion of New Zealand.

The Ministry for the Environment uses IPCC default methodology to calculate carbon stock change in organic soils.

Find out more

Guidance the Ministry for the Environment uses when measuring soil carbon.

Soil data are available to central and local government agencies, research institutes, universities and other organisations, see Forest, soil and LiDAR data.

Reviewed:
27/05/15