Measurement of soil carbon sequestration in agricultural systems method

The business case for carbon farming: improving your farm’s sustainability

TYPE: Sequestration methodology


This method credits measured increases in soil carbon as a result of one or more new or materially different management activities in grazing or cropping land (including woody horticulture) that store carbon in that land.
Soil carbon stocks must be estimated using specified soil sampling methods and samples must be measured for soil carbon content using specified laboratory techniques or calibrated in-field sensors.

Methodology details
Management actions
Soil Carbon in Grazing Systems projects can use a range of actions to build soil carbon, as long as at least one of the project management actions is new. Projects must introduce one or more of the following activities:
  • apply nutrients to the land
  • apply lime to remediate acid soils
  • apply gypsum to remediate sodic or magnesic soils
  • undertake irrigation activities from new irrigation efficiency savings
  • re-establish or rejuvenate a pasture by seeding establishing, or permanently maintaining, a pasture where there was previously no pasture, such as on cropland or bare fallow
  • alter the stocking rate, duration or intensity of grazing
  • retain stubble after a crop is harvested
  • convert from intensive tillage practices to reduced or no tillage practices
  • modify landscape or landform features to remediate land (e.g. undertake water ponding), or
  • use mechanical methods to add or redistribute soil.
Choosing a suitable management action or actions to build soil carbon is a decision the person responsible for running a project must make.
There is no guarantee that any one of the management actions listed here will build soil carbon on any particular property and it is recommended that proposed project management actions are researched and expert advice sought on what will best suit a particular project area. 
The Clean Energy Regulator will need evidence showing that at least one of the project management actions is new and that the project management actions as a whole will have a reasonable chance of increasing carbon inputs into the soil, reducing soil carbon losses, or both.

Project location requirements
Projects must include ‘eligible land' that has been used for:
  • pasture
  • cropping (including perennial woody horticulture)
  • bare fallow
  • or any combination of these for the previous 10 years
A land management strategy must be prepared or reviewed by an independent person—advising on what management activities are best suited to the site, including information on risks, monitoring and improvements. 
Areas of eligible land in which carbon abatement is to be measured (carbon estimation areas) must not be:
  • forest land
  • land that was a wetland in the previous 10 years, or
  • include dwellings or other structures.
Land that cannot be classified as a carbon estimation area may still be part of a project area, as either an exclusion zone or emissions accounting area. These areas cannot contribute to crediting of carbon abatement under the method.

Conducting baseline soil sampling
A baseline sampling round must be undertaken to measure soil carbon stocks in carbon estimation areas in the first reporting period for new projects, or within 18 months of land being added to an existing project area. A subsequent sampling round must be conducted in every reporting period in the crediting period (including the first reporting period).
An independent person must extract soil cores and measure soil carbon using laboratory measurements or laboratory calibrated in-field sensors. A consistent soil carbon estimation technology (for example, combustion or sensors) must be used within each carbon estimation area and each sampling round.
Each carbon estimation area must be divided into at least three strata (subdivisions), and at least three soil cores must be taken from each strata. 
NOTE: An advance payment worth up to $5,000 is available through a pilot program for eligible Emissions Reduction Fund (ERF) projects to help with upfront costs of soil sampling.
Calculating net abatement
Net abatement (the amount used for crediting ACCUs) corresponds to the increase in soil carbon over time, after the emissions caused by additional activities used to build soil carbon (for example extra fertiliser applications beyond the baseline) have been subtracted.
Due to the impact of climatic, temporal and spatial variability on soil carbon stocks, the method applies a temporary discount to increases in soil carbon stocks after the second sampling round (withheld credits are effectively refunded if soil carbon stock increases are maintained after the third sampling round) as well as ongoing discounts for statistical uncertainty. These discounts reduce the risk of overestimation of carbon stock increases and of over-crediting. The ongoing discounts decrease as the certainty of soil carbon estimates increase.

Record keeping requirements
The methodology includes very detailed record keeping requirements. Essentially, auditable standard records must be kept for each soil sampling round, for emissions from other sources within the project areas, and for all project management actions.
In addition to the general requirements for all Emissions Reduction Fund projects, proponents participating under this method must:
  • notify the Clean Energy Regulator of events that change the management activities, sampling locations or land management strategy prior to each sampling round
  • keep records relating to land management activities, the independent person involved in a sampling, and the project's land management strategy and other compliance requirements, and
  • monitor livestock details in the project, tillage, harvested product, removed crop residues as well as inputs of fertiliser, biochar, lime, electricity and fuel.
NOTE: The 2015-16 method prioritisation process resulted in an agreement that a new soil carbon method should be developed building on the two existing soil carbon methodologies. The need was identified as there had been limited uptake of the existing soil carbon methods. This outcome was attributed to the narrow range of farming systems that were able to participate and the high costs of direct measurement.
The Carbon Credits (Carbon Farming Initiative—Measurement of Soil Carbon Sequestration in Agricultural Systems) Methodology Determination 2018 sought to overcome these limitations by introducing new components and adapting some components from the two earlier soil carbon methods. The major differences include:
  • an improved soil sampling strategy to reduce uncertainty of soil carbon estimates, supporting the participation of a wider range of production systems;
  • an increased range of eligible farming systems including cropping, grazing and horticultural production systems;
  • allowing the use of soil amendments containing biochar and accounting for other additives that may contain carbon, including clay;
  • an additional measurement option allowing for the ability to estimate carbon stocks using in-field or laboratory sensors and associated models as well as the combustion techniques;
  • a ten year baseline period; and
  • use of a land management strategy, to be developed or reviewed by an independent person.

Source: EXPLANATORY STATEMENT issued by the Authority of the Minister for the Environment and Energy, Carbon Credits (Carbon Farming Initiative) Act 2011, Carbon Credits (Carbon Farming Initiative-Measurement of Soil Carbon Sequestration in Agricultural Systems) Methodology Determination 2018