A soil-carbon claim becomes more useful when a buyer can examine how it was measured, how uncertainty was handled and what the farmer receives. Groundwork BioAg’s Rootella Carbon programme has obtained a BBB rating from BeZero Carbon, bringing those questions into focus for agricultural carbon removal.
Separate a biological mechanism from a verified outcome
The programme uses mycorrhizal inoculants to support plant-root interactions and the transfer of carbon into soil. It operates in the United States under Verra’s VM0042 methodology for improved agricultural land management. The company reports removal rates of 1.5–3.5 tonnes of carbon dioxide equivalent per acre, or roughly 4–9 tonnes per hectare annually. These are programme claims, not a universal expectation for every soil or crop.
The mechanism alone does not establish how many credits can be issued. Quantification must examine changes in carbon stocks and compare them with an appropriate baseline. The programme emphasises physical soil sampling rather than relying entirely on modelled estimates, giving its assessment a direct connection with measurements taken in participating fields.
Make the measurement design visible
For its initial cohort, Groundwork BioAg describes 593 sampling points taken to a depth of 30 centimetres and 915 matched pairs of treated and control fields. The comparison process applies similarity criteria under the methodology. Matching matters because soil properties and growing conditions can vary, making a simple difference between unrelated fields difficult to interpret.
The company also reports a 26.43% uncertainty deduction for the first monitoring period. Such a deduction reduces the quantity credited rather than treating the central estimate as certain. For a buyer assessing a carbon project, the sampling design and treatment of uncertainty are therefore as relevant as the headline removal figure.
Consider persistence and farmer incentives
Agricultural carbon projects must address additionality and the risk that stored carbon could later be lost. Groundwork BioAg links its approach to the formation of longer-lived soil organic matter and argues that carbon income can encourage adoption of the biological input. The programme allocates up to 70% of net project proceeds to participating growers, tying the commercial model to continued farm participation.
The programme has reported an issuance of 19,568 tonnes of carbon dioxide equivalent and plans a substantially larger future supply. Those plans remain dependent on verification and demand. An independent rating can inform a purchasing decision, but it does not turn a projection into issued credits or remove the need to examine the underlying project evidence.
For growers, the practical questions include sampling commitments, contractual responsibilities, payment calculations and how management changes are recorded. Clear answers make it easier to judge whether participation supports the farm’s own priorities. Reliable measurement links the environmental claim to a commercial arrangement that both the buyer and the farmer can understand.
