March 10, 2025.5 minutes

From credit to credibility: Quantifying and creating high-integrity carbon credits

Marcos Alves, Andrew Manderson and Petros Georgiadis

Creating credits from the soil takes time, measurement and data. Most importantly, the process begins with a farmer changing their farming practices, from conventional to regenerative methods. Empowering farmers by rewarding their transition to regenerative agriculture can have an enormous impact on both the climate and farmers themselves, with soil carbon credits acting as a financial incentive to begin and commit to a regen ag transition. High-integrity soil carbon credits, such as the ones produced by the AgreenaCarbon Project, align with the Core Carbon Principles (CCPs), including independent third party auditing, robust data collection and calculations, evidence of additionality and monitoring of permanence.

For Agreena, this process begins by establishing a credible baseline, informed by a review of historical field data, spanning the five years preceding entry into the AgreenaCarbon Project. Verra’s Verified Carbon Standard (VCS) VM0042 methodology for ‘Improved agricultural land management’ requires that, for each new field, Agreena determines what “business as usual” would look like in the absence of additional improved practices (e.g. tillage type or fertiliser type). Identifying the field baseline information enables effective and efficient soil sampling, and annual field practice data (once in the project) provides the core inputs for greenhouse gas (GHG) removal and reduction calculations.

Data is key for soil carbon calculations using the ‘Measure and model’ approach from VM0042. At Agreena, we use and collect data from soil sampling, scientific literature, farmer-reported metrics, and publicly available climatic data. The ‘Measure’ of the ‘Measure and model’ ensures soil sampling plays a central role in grounding the ‘Modelled’ calculations in real-world observations. Soil samples are collected from representative locations, paying close attention to differences in soil type, climate zones, and field management histories.

Remote-sensing technology verifies that regenerative farm practices, such as reduced tillage and/or the growth of cover crops, have taken place on farms, forming the backbone of Agreena’s measurement, reporting and verification (MRV) methodology.

Combining all of this information together provides the dataset for calculations. This data is also subject to the aforementioned additional quality checks, and is augmented using various publicly available data, so that the final dataset contains verified information on:

1. 1

   Historic practices

2. 2

   Annual field practices

3. 3

   Soil data

4. 4

   Climate data

The resulting dataset is then processed through two calculation pipelines: 1) the process-based model RothC and 2) a series of equations established in VM0042 for calculating GHG emission reductions.

The RothC model used in the AgreenaCarbon Project is specifically calibrated for the project area to capture changes in soil organic carbon (SOC) stocks resulting from fertiliser inputs, residue management, cover crops, and tillage practices. The resulting SOC change represents the atmospheric carbon removals. The second pipeline estimates GHG emission reductions, accounting for practices related to reducing synthetic fertiliser use or fossil fuel intensity. Once the project’s data is consolidated, the two calculation pipelines generate estimates of carbon sequestered and emissions reduced.

These raw outputs of carbon removals and GHG emission reductions calculations do not directly translate into credits. Potential sources of overestimation risk must be addressed — most notably, leakage, uncertainty and buffer.

Leakage occurs if reduced emissions on a project field lead to increased emissions elsewhere — for example if straw residue is mulched into a field instead of sold off-field to a local energy plant, it could lead to increased coal burning for energy generation. To account for this potential leakage, productivity declines, livestock displacement, and diversion of crop residues are assessed for impact and accounted for in the project, regardless of how minimal the likelihood may be. Uncertainty deductions address the variance in both model estimations and soil sampling results that may affect the final results. These deductions ensure that final credit numbers are not over-estimated.

Finally, a buffer serves as insurance against potential reversal of farm practices in a field, such as carbon losses caused by extreme weather events or changes in farm management. A complete risk analysis is carried out and reported, determining how many credits must be set aside as a contingency measure. Although this reduces the volume of tradable credits, it solidifies their integrity and reduces risk. Any unanticipated disturbance will not invalidate the credited climate benefits; if a reversal does occur, the buffer covers the shortfall.

This robust process underpins confidence in our soil carbon credits. Far from a simplistic “one tonne in the soil equals one credit” scenario, high-integrity projects such as AgreenaCarbon undergo a rigorous sequence of data collection, modelling, third-party review, and conservative deductions before any carbon credits are issued. By adhering to methodologies like VM0042, employing robust soil sampling plans, leveraging a mix of remote sensing and on-site verification, and adopting insurance mechanisms to address both leakage and reversals, carbon projects can minimise the risk of issuing ineffective credits. The result is a trustworthy system in which each credit genuinely reflects a net climate benefit grounded in rigorous science and transparent documentation.

Orders for Verra-certified carbon credits are open.

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From credit to credibility: Explore the series

In this series, we're sharing an overview of what it's taken to build a carbon project that meets the highest of standards – Verra’s VM0042 methodology. This series of articles introduces the Agreena team that have worked closest to the project and continue to support the next steps to verification and issuance.

In this series you hear from:

1. Karolina Kenney, Senior Standards Specialist; outlining the processes of building a project with the highest integrity for the market;

2. Katja van Overeem, Blayne Lees and Ben Smith of the Data teams; explaining Agreena's work to ensure integrity of on-farm data capture at scale.

3. Dr Petros Georgiadis, Dr Marcos Alves and Dr Andrew Manderson from the Agreena Science and Statistical teams; unravelling the methodology to calculate soil carbon credits through sampling and modelling together;

Roberta McDonald, Head of Programme

From credit to credibility: Building a high-integrity soil carbon project

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From credit to credibility: The importance of data verification

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