The Australian government plans to limit crediting under the soil carbon methodology after a periodic review found potential over-crediting risks, the Department of Climate Change, Energy, the Environment and Water (DCCEEW) has announced.
The Emissions Reduction Assurance Committee (Erac) — the statutory body responsible for ensuring the integrity of Australia's carbon crediting framework — recommended an \"immediate risk mitigation strategy\" for the Soil Organic Carbon 2021 method as it identified some existing projects reported soil organic carbon accumulation rates above levels supported by peer-reviewed scientific literature, the DCCEEW said on 28 July.
Under the proposed changes, credited abatement would be capped to an equivalent of 3 t/yr of soil organic carbon per hectare, for projects with a 25-year permanence period, after permanence and risk of reversal discounts are deducted.
Projects with 100-year permanence periods, which are not subject to an existing 20pc permanence discount, would face a higher crediting cap of 3.8 t/yr per hectare — although there are only seven of such projects out of 823 currently registered under the method, according to the latest Clean Energy Regulator (CER) data.
Project developers earn Australian Carbon Credit Units (ACCUs) under the method by increasing soil carbon stocks in pasture, crops, horticultural or mixed farming systems through activities such as rotational grazing adjustments, pasture enhancement, and improved fertilizer or nutrient management.
They can use both a measurement-only approach and a hybrid approach that combines soil carbon model estimates with soil sampling to calculate soil carbon changes. Sampling rounds need to take place every 1-5 years during the 25-year crediting period for projects.
The proposed caps are cumulative, which means that carbon stored faster than the annual rate would not be lost if subsequent sampling rounds confirmed levels were maintained. Total credited abatement would be 75 t/ha for projects with 25 years of permanence period and 95 t/ha for those with 100 years.
Apart from the proposed crediting caps, the DCCEEW is consulting on options to improve sampling and stratification protocols to increase measurement reliability and representativeness, with feedback to be sent by 18 August.
Industry organisations like the Soil Carbon Industry Group (SCIG) and the Carbon Market Institute (CMI) welcomed the release of the periodic review and the public consultation.
The review sets out a practical path for improving the method and supporting its continued development, for an industry now operating across more than 1mn hectares of Australian farmland, the SCIG said.
The proposed 3 t/yr per hectare cap, which would be equivalent to approximately 11 ACCUs, is \"pragmatic\", the organisation noted.
Existing projects continue, ACCUs already issued are unaffected, and new project registrations remain available, project developer Agriprove noted. The company has more than 650 soil carbon projects currently registered with the CER — the largest for a single developer across the entire ACCU scheme, making up 25pc of the over 2,600 of currently valid projects.