What is SAT-C and Why Does it Matter for Measuring Enhanced Rock Weathering?

Enhanced rock weathering (ERW) depends on robust measurement techniques that consistently work in all soil types, under variable weather conditions, across all seasons.

That is the challenge SAT-C was developed to help solve. Short for SATuration-Centrifugation, SAT-C is UNDO’s proprietary, patent-pending soil porewater extraction technique, designed to recover reliable porewater data even when field conditions make traditional sampling challenging. At its core, SAT-C is about improving the quality, consistency, and effectiveness of the data that underpins ERW measurement.

What is SAT-C?

SAT-C is a soil porewater extraction method developed for enhanced rock weathering measurement. It combines intact soil core collection, controlled saturation using deionised water, and centrifugation to recover porewater for chemical analysis. Rather than relying on field moisture conditions at the time of sampling, SAT-C moves part of the extraction process into a more controlled environment.

That shift is important. In practical terms, SAT-C is designed to recover porewater from a defined soil volume irrespective of in-situ moisture conditions. That makes it different from traditional porewater extraction approaches, which often rely on the soil already being sufficiently wet to yield a usable sample. In ERW, where researchers need dependable datasets across variable conditions, that distinction matters.

SAT-C is not just a lab technique for extracting water from soil. It is a measurement method designed to support better interpretation of weathering chemistry, greater continuity across datasets, and more reliable carbon accounting over time.

Why was SAT-C Developed for Enhanced Rock Weathering?

Enhanced rock weathering takes place in open, living systems. Water moves through soil unevenly. The weather changes from week to week and season to season. Dry periods can interrupt sampling. Soil structure varies between sites. All of that makes measurement more complex than it would be in a closed or highly controlled system.

Traditional porewater extraction methods, such as rhizons and lysimeters, are widely used, but they can be constrained by moisture availability. That can create several challenges for ERW monitoring:

– data gaps during dry periods

– lower comparability across seasons and sites

– uneven sample yields

– uncertainty when interpreting time series data

SAT-C was developed to reduce that dependence on field moisture and help create richer, continuous MRV data. The goal was not simply to recover more porewater, but to do so in a way that supports a more robust scientific interpretation.

Who Developed SAT-C And Why Does Collaboration Matter?

SAT-C was developed to solve a practical measurement challenge in enhanced rock weathering, but it was not developed in isolation. The peer-reviewed paper was co-authored by scientists at UNDO Carbon alongside collaborators from Newcastle University, The James Hutton Institute, and independent researchers. That matters because reliable ERW measurement depends on expertise across field science, soil chemistry, geochemistry, and carbon accounting, not just one part of the system.

This collaborative approach helps ground SAT-C in the broader scientific work required to measure ERW effectively. It also means the method has been evaluated through peer review, giving it a stronger footing as part of the growing scientific toolkit for ERW measurement. Alongside this scientific collaboration, UNDO has also worked with McLaren Racing engineers on a prototype soil auger as part of wider SAT-C research and development, helping improve the soil sampling process that supports the method. As the field develops, that combination of practical field experience, external collaboration, and peer-reviewed research is an important part of building confidence in the measurement of carbon removal.

Why is Soil Porewater Important in Enhanced Rock Weathering?

Soil porewater is the water held in the spaces between soil particles. Because it moves through the soil and interacts directly with minerals, roots, microbes, and dissolved compounds, it provides a valuable window into what is happening below ground.

In ERW, porewater matters because it can contain the dissolved products generated as silicate minerals weather. These include bicarbonate alkalinity and dissolved cations such as calcium, magnesium, sodium, and potassium. Tracking changes in those dissolved species helps researchers understand how weathering is progressing and how that chemistry may relate to carbon dioxide removal.

Porewater is also important because it helps researchers do more than observe change. It can be used to:

– determine cation fluxes, which act as a proxy for carbon dioxide removal

– distinguish the strong acid weathering fraction

– support the interpretation of how much of the weathering contributed to CDR

That is why porewater remains important even when other methods are used to track weathering. 

How Do Traditional Porewater Extraction Methods Work?

Traditional porewater extraction methods, such as rhizon samplers and suction lysimeters, work by drawing water through a porous interface while the sampler is in the soil. They are established tools in soil science and can work well in the right conditions. But they are also strongly affected by soil moisture and pore connectivity.

When soils are sufficiently wet and the pore network is well-connected, these methods can produce usable samples. But when soils are dry or frozen, problems become more common. These can include:

– little or no sample yield

– vacuum loss due to air ingress

– variability across soil types

– lower continuity in sampling over time

That matters for ERW because researchers are not trying to capture a single moment. They are trying to build a dataset that holds together over time. If a method works well only under certain moisture conditions, it can become harder to compare results across the full season or across different regions.

How Does The SAT-C Process Work?

SAT-C moves extraction into a more controlled workflow. Instead of relying on the soil being wet enough in the field, the method begins by collecting intact soil cores and then applying a standardised saturation and centrifugation process in the lab.

The process follows these steps:

– Intact soil cores were collected using stacked metal rings

– The lower core, from the 5 to 10 cm depth interval, was retained

– The sample was fitted with gauze, capped, and weighed

– The core was saturated with deionised water in a sealed bag

– Saturation took place at 4°C for either 24 or 72 hours

– The core was then centrifuged at 1000 rpm for 30 minutes

– The extracted supernatant was filtered and analysed for chemistry

The logic behind this approach is straightforward. By fixing the soil volume and standardising the saturation step before extraction, SAT-C aims to reduce the influence of short-term field moisture conditions on whether a sample can be recovered and how comparable that sample is to others.

Why Use Controlled Saturation and Centrifugation?

The controlled saturation step is what allows SAT-C to reduce dependence on in-situ soil moisture. Rather than treating wet and dry samples as fundamentally different starting points, the method brings them to a consistent state before extraction. That helps create a more standardised basis for porewater recovery.

Centrifugation then provides a way to recover that porewater from the intact core without relying on natural drainage conditions in the field. Importantly, the study identified a centrifugation setting that was sufficient to extract porewater while preserving the integrity of the soil sample. The selected condition was 1000 rpm for 30 minutes.

This matters because extraction is not only about quantity. It is also about quality. A method that changes the sample too aggressively risks altering the chemistry or the physical structure in ways that make interpretation harder. SAT-C was developed to strike a balance between recovery and representativeness.

What Makes SAT-C Different from Standard Soil Water Extraction Methods?

One of the most important differences is that SAT-C is designed around a defined soil volume. That means researchers know the physical sample they are working from, rather than relying on a less certain in-situ sampling zone. In ERW measurement, that matters because it supports clearer comparisons between samples and a more consistent interpretation over time.

Another difference is that SAT-C does not just produce aqueous data. Because it recovers intact soil cores, the same samples can also support:

– Aqueous chemistry

– Solid-phase characterisation

– Bulk density data

That is a major advantage. Pairing aqueous and solid-phase data, along with bulk density, from the same sample yields a more internally consistent dataset. It also reduces the risk of introducing extra noise when different measurements are taken from different samples or nearby but not identical locations.

Why Does Bulk Density Matter in SAT-C?

Bulk density is a measure of how much dry soil is packed into a given volume. In simple terms, it helps show how dense or compact a soil sample is. That matters in enhanced rock weathering because researchers often need to translate measurements taken from a small soil core or monitoring plot into estimates that apply across a wider area. To do that well, they need to know not just the chemistry of the sample, but how much soil that sample represents.

In many measurement systems, bulk density is collected separately from the main MRV sample. That can create small mismatches between datasets, especially when soil properties vary across short distances. Because SAT-C recovers intact cores, bulk density can be measured from the same sample used for aqueous and solid-phase analyses. This helps reduce uncertainty, improves internal consistency, and makes it easier to build a dataset that holds together when CDR estimates are scaled up.

What does SAT-C Make Possible?

SAT-C makes it possible to build a more complete picture of weathering from a single sampling event. Rather than generating only porewater chemistry, the method can link aqueous data with solid-phase characterisation and physical soil measurements from the same intact core. That gives researchers a more joined-up view of what is happening in the soil, rather than asking them to piece together results from separate samples taken at different times or locations.

In practice, SAT-C can support:

– More reliable porewater recovery under dry or variable conditions

– Stronger continuity in time series datasets

– Better linkage between dissolved chemistry and solid-phase data

– Bulk density measurements from the same sampling event

– Improved internal consistency when scaling up CDR estimates

Taken together, these advantages make SAT-C more than just a porewater extraction method. It helps create a stronger overall measurement framework, one that is better suited to the complexity of real-world ERW monitoring.

Why Does SAT-C Matter Beyond One Study or One Region?

Although SAT-C was developed in an ERW context, the challenge it addresses is broader. Seasonal drying, variable soil moisture, and patchy porewater recovery can affect soil monitoring in agriculture, land restoration, and environmental remediation, too. A method that improves reliability under those conditions may therefore have scientific value beyond enhanced rock weathering alone.

That wider relevance is part of why SAT-C matters as a concept, not just as a single piece of research. It is a process innovation aimed at making a difficult type of soil chemistry measurement more practical, more consistent, and more useful. As ERW expands into a wider range of climates and operating environments, that kind of measurement resilience becomes more important.

Since the initial study was completed, validation work for SAT-C has also been expanded at scale in UNDO’s Canadian field trials, with supporting results due to be presented at Goldschmidt in Montréal in July 2026. That ongoing work reinforces the idea that SAT-C is being developed not only as a promising method on paper but also as a practical measurement process for real field settings.

Strengthening The Science Of ERW Measurement

As enhanced rock weathering has moved from small trials to larger-scale deployments, the quality of measurement has become increasingly crucial. It is not enough to know that weathering is happening in theory. Researchers, verifiers, and buyers need methods that perform consistently in field conditions and produce datasets detailed enough to support robust interpretation. That is where SAT-C has real value. Improving how porewater is recovered and linking aqueous chemistry, solid-phase data, and bulk density from the same sample strengthens the scientific foundations on which ERW measurement depends.

The greater significance of SAT-C is that it points toward a more practical and more mature approach to monitoring enhanced rock weathering, one where data collection is less constrained by short-term soil moisture conditions, measurements are easier to compare over time, and the evidence base grows stronger as the field develops. As ERW expands into new regions and more varied climates, methods like SAT-C will be important not just for answering today’s questions, but for helping shape how the science of carbon removal is measured in the years ahead.

Want To Talk To Our Team About SAT-C?

If you’d like to learn more about the science behind SAT-C, enhanced rock weathering measurement, or UNDO’s wider research, get in touch with us.

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