Monitoring soil carbon

For the first time in New Zealand, a systematic, long-term national study is underway to quantify changes in soil carbon stocks under different agricultural land uses over time.

Current projects

Project title Lead organisation/s
Implementation of a national soil carbon benchmarking and monitoring system for agricultural land in New Zealand Manaaki Whenua


Storing additional carbon in soils provides a potential route for offsetting greenhouse gas emissions from agricultural activities. Currently, New Zealand lacks comprehensive data on whether our agricultural soils are gaining or losing carbon. Given the multiple influences on soil carbon storage processes, only a systematic long-term study will be able to provide these data.

See the Science of soil carbon page for information on how carbon is stored in soils and the factors that influence that process.

In 2019, the first phase of a planned 12-year NZAGRC-funded study commenced. This project will improve estimates of soil carbon stocks under the broad agricultural land uses of cropland, perennial horticulture, dairy, drystock on flat/rolling land and drystock in hill country and determine whether changes are occurring over time within any of these land uses.

Map showing sampling sites for the national soil carbon benchmarking and monitoring study

Sampling sites for the national soil carbon benchmarking and monitoring study

Historic data have been used to develop a sampling approach capable of detecting a 2 tonnes per hectare change in soil carbon stocks, with samples taken at 3-4-year intervals.

The study will sample about 500 statistically selected sites around the country, to a depth of 60cm. Samples will be taken by experienced teams using a standard methodology and analysed in Manaaki Whenua’s IANZ-accredited laboratory.

Data from the study will help to support the NZAGRC’s long-term aim of identifying farm-management practices that maintain or increase soil carbon stocks under New Zealand conditions. The study will also improve estimates of how soil carbon stocks change if land use changes. It will therefore increase the accuracy of national reporting on soil carbon stock changes.