Inside UNDO’s On-Farm Research: Small Plot Monitoring Sites in Eastern Ontario

Every farmer knows that no two sections of a field are exactly alike. Soil pH shifts, drainage changes with the slope, and what works on one farm doesn’t always translate to the next. 

That variability is one of the realities of farming in Eastern Ontario, and it’s one of the reasons that understanding how wollastonite performs in agricultural conditions is so important.

Laboratory research can establish the chemistry, but it cannot account for the full complexity of a working farm: the seasonal weather patterns, the range of soil types, the different cropping systems, and the practical pressures that shape how land is managed year to year. 

That’s why UNDO has established a network of Small Plot Monitoring Sites, or SPMS, on farms across South Eastern Ontario. These controlled, on-farm research trials generate detailed soil and crop data from working fields during active growing seasons.

The Importance of Field-based Research

Enhanced rock weathering (ERW) works by spreading finely crushed silicate rock on agricultural land. As wollastonite weathers in the soil, it reacts with CO₂ dissolved in rainwater, converting it into bicarbonate alkalinity that is transported to the oceans and stored on geological timescales. Alongside that carbon removal process, the weathering releases calcium and silicon into the soil: nutrients that can help support pH stability, soil structure, and crop resilience over multiple growing seasons.

The scientific case for wollastonite is well established, and a growing body of field evidence is reinforcing it. But to reliably quantify carbon removal and understand agronomic outcomes across the diversity of soils and climates that make up Eastern Ontario, we’re building the science from the ground up through on-farm research. 

UNDO’s SPMS network exists because farmers have opened their land to scientific monitoring, and in doing so, they’re helping build the evidence base that benefits the whole program, including farms already part of it.

What is an SPMS, and how does it work on-farm with UNDO?

A Small Plot Monitoring Site is a 2.5-acre research trial set up within a working field. While on-farm plot trials exist across agricultural research more broadly, UNDO’s SPMS program is designed specifically around the requirements of ERW science: tracking how wollastonite weathers under field conditions, how carbon removal unfolds over time, and what that means for the soil and crops growing above it.

Within the 2.5-acre trial area, wollastonite is applied across six groups of plots, each group testing four different application rates. That variation enables the comparison of outcomes at different application densities within the same field. UNDO’s science team can then observe how wollastonite behaves across a controlled range of conditions and build a precise, calibrated understanding of its effects. The rest of the field is left untreated. Farmers plant and manage the trial area in exactly the same way as the rest of their operation.

The wollastonite used in UNDO’s Canadian program is sourced locally from Canadian Wollastonite, near Seeley’s Bay. It is a natural calcium silicate mineral, approved by the Canadian Food Inspection Agency (CFIA) for use as a fertilizer, and suitable for certified organic farming systems. Spreading uses standard agricultural equipment and is coordinated around the farm’s existing calendar.

What does the research actually measure?

The data collected at each SPMS site covers three interconnected areas: the soil itself, the crops growing in it, and how both change over time as the wollastonite weathers.

– Soil sampling takes place every four weeks throughout the season. UNDO’s field technicians measure pH, cation exchange capacity (CEC), and soil texture at each visit, tracking how the soil’s chemical environment shifts as calcium and other minerals are released from weathered rock. These aren’t one-off snapshots: they’re a continuous record built up across multiple growing seasons.

– Crop tissue samples are collected throughout the growing season to measure nutrient uptake and plant health at different stages of development, giving a picture of how what’s happening below the surface is being expressed in the crop itself.

– Yield data is collected from within the trial plots at harvest, providing a direct measure of crop performance relative to a documented soil baseline.

For participating farmers, those findings don’t disappear into a research database. Each year, UNDO provides a report summarising the results from their land: soil pH trends, nutrient levels, and crop performance data from their specific acres. For farms already monitoring soil health or managing pH across their fields, that kind of granular, site-specific data has genuine practical value independent of the carbon removal science it also supports.

Why Eastern Ontario’s variability makes this research so valuable

A 2025 survey of Ontario crop producers found that “65% of respondents were very concerned or concerned about drought risk affecting their yields”, and a similar proportion expressed concern about soil degradation. Those are not abstract concerns. They reflect the pressures that Eastern Ontario farmers are managing season by season, and they’re directly relevant to the questions that UNDO’s SPMS program is working to answer.

Calcium from the weathering rock can help buffer soil pH and support the structure that makes nutrients available to roots, including the improved clay flocculation and water infiltration that come with better soil aggregation. Silicon is taken up directly by crops and incorporated into cell walls, which can improve standability, regulate leaf transpiration for better water-use efficiency, and build resilience to drought stress, disease pressure, and heat. In Ontario, an in-field hay trial, wollastonite-treated fields have shown more even stands and stronger plants compared to untreated areas.

But these effects don’t play out identically across every field. Clay-heavy soils behave differently from lighter ones. Fields with variable drainage respond differently to the same application rate. The SPMS network is specifically designed to capture that variability rather than eliminate it. Each site adds a data point that helps us understand the range of conditions under which wollastonite performs, and what that means for farms across the region.

What to expect if your farm hosts an SPMS

The process from initial interest to an established site follows a clear sequence, with UNDO’s team managing each stage in coordination with the farmers we work with.

Qualification soil sampling

Before any site is established, UNDO conducts a second round of soil sampling in the proposed 2.5-acre area. This checks that the pH, cation exchange capacity, and soil texture of the specific location meet the criteria needed for a reliable trial.

– Results come back within one to two weeks.

– If the field qualifies, the conversation moves on to paperwork and logistics.

– If it doesn’t qualify at this stage, the team will talk through why and whether alternative areas of the farm might be suitable.

Paperwork and payment

Once a site is confirmed, UNDO and the farmer review a contract covering the land the SPMS occupies.

– Farmers who host an SPMS receive annual financial compensation for the duration of the trial, with a bonus payment after three years.

– Exact figures are discussed directly with the team as part of this process.

Site installation

Installation takes approximately one week.

– A small team of two to four people visits the trial area each day to conduct additional soil sampling and to spread wollastonite at four application rates across the plot groups.

– Spreading uses a small tractor and a rear-mounted spreader.

– The rest of the farming operation is unaffected throughout.

Ongoing monitoring

Once the site is running, two to four field technicians return every four weeks to take soil samples.

– UNDO coordinates each visit with the farmer in advance, checking on any recent fertilizer or manure applications, so sampling can be scheduled accordingly.

– Before any tilling, plowing, or harvesting in the trial area, farmers are asked to give the team advance notice so that monitoring equipment can be moved clear without interrupting field operations.

– The one consistent requirement for the trial area is that lime, biochar, or other substances related to enhanced rock weathering are not applied within the SPMS boundary, as this would affect the integrity of the results.

How SPMS data feeds into ERW science

Individual SPMS sites do more than generate farm-specific reports. The data they produce feeds into UNDO’s broader monitoring, reporting, and verification (MRV) infrastructure: the scientific framework that underpins the carbon removal claims that carbon buyers, regulators, and scientific partners rely on.

For ERW to function as a credible carbon removal pathway, it needs robust, field-level evidence of what’s happening in the soil. How quickly does wollastonite weather under different conditions? How does carbon removal vary with application rate, soil type, and climate? How do agronomic outcomes track alongside carbon removal over multiple seasons? These are questions that can only be answered with sustained, in-field measurement, and each SPMS site contributes to that answer.

UNDO works with a range of institutional partners to advance this science, including Area X.O, Queen’s University, University of Washington, and the University of Guelph. The SPMS network in Eastern Ontario is part of the same broader commitment to measurement-first research that runs through UNDO’s approach globally: building credibility through data, not through claims alone.

The Research That Runs Through Eastern Ontario’s Fields

The agricultural lands of Eastern Ontario currently host some of the most comprehensive on-farm research initiatives for enhanced rock weathering. The data from UNDO’s Small Plot Monitoring Sites are building a detailed, field-level picture of how wollastonite performs across soils and growing seasons. Farmers get independent, site-specific data on their own land, annual reports on soil and crop performance, and financial compensation for hosting the trial. UNDO gets the evidence base it needs to advance the science of carbon removal measurement and verification.

Across multiple growing seasons, that data accumulates into something larger than any single farm can see from the ground: a credible, measured account of what ERW looks like in practice, across the full range of conditions that Eastern Ontario agriculture presents.

Want To Find Out If Your Farm Could Host an SPMS?

If you're interested in hosting one of UNDO's Small Plot Monitoring Sites, or want to learn more about what's involved, get in touch with the team.

Speak to the team