Key facts
- Australia plans to cap soil carbon crediting due to over-crediting risks.
- The Emissions Reduction Assurance Committee recommended an "immediate risk mitigation strategy".
- Credited abatement will be capped at 3 t/yr per hectare for projects with a 25-year permanence period.
- Projects with 100-year permanence periods will face a higher cap of 3.8 t/yr per hectare.
- The government is consulting on improving sampling and stratification protocols.
The Australian government intends to impose limits on soil carbon crediting under its methodology, citing concerns about potential over-crediting identified in a recent review. The Department of Climate Change, Energy, the Environment and Water (DCCEEW) announced the proposed changes following a recommendation from the Emissions Reduction Assurance Committee (Erac).
Erac, responsible for the integrity of Australia's carbon crediting framework, advised an "immediate risk mitigation strategy" for the Soil Organic Carbon 2021 method. The committee found that some existing projects reported soil organic carbon accumulation rates higher than those supported by peer-reviewed scientific literature.
Under the proposed changes, credited abatement would be capped. For projects with a 25-year permanence period, the cap would be equivalent to 3 tonnes of soil organic carbon per hectare per year, after accounting for permanence and risk of reversal discounts. Projects with a 100-year permanence period, which are not subject to a 20% permanence discount, would face a higher cap of 3.8 tonnes per hectare per year. Currently, only seven of the 823 registered projects under this method have a 100-year permanence period, according to Clean Energy Regulator data.
Project developers earn Australian Carbon Credit Units (ACCUs) by increasing soil carbon stocks through various farming activities. They can use either a measurement-only approach or a hybrid method combining soil modelling with soil sampling. Sampling rounds are required every one to five years during the 25-year crediting period.
The proposed caps are cumulative, meaning faster carbon storage rates would not be lost if subsequent sampling confirms sustained levels. Total credited abatement would be 75 t/ha for 25-year projects and 95 t/ha for 100-year projects.
In addition to the crediting caps, the DCCEEW is seeking feedback on options to enhance sampling and stratification protocols to improve measurement reliability and representativeness. Feedback is due by August 18.
Industry groups, including the Soil Carbon Industry Group (SCIG) and the Carbon Market Institute (CMI), welcomed the review and the public consultation. SCIG described the review as setting out a practical path for improving the method and supporting its development across over 1 million hectares of Australian farmland. They also noted the proposed 3 t/yr per hectare cap, equivalent to about 11 ACCUs, as pragmatic.
Project developer Agriprove stated that existing projects and already issued ACCUs are unaffected, and new project registrations remain available. Agriprove manages over 650 soil carbon projects, representing 25% of all valid projects in the ACCU scheme.