FEATURE: Can technology unlock soil's full carbon potential?

They turned up in SUVs, on motorbikes and, as rumour had it, even on horseback, burnishing credentials that stated they were here to verify carbon credits by the UN.

The year was 2007 and all over the Brazilian state of Minas Gerais plastic domes were popping up over concrete basins dug out on farmland, PVC pipes snaking out across some of the most fertile land on the continent expelling methane into the air.

Fifteen years ago, verifiers of emission reductions for the burgeoning carbon credit market had their work cut out.

They arrived in areas of remote eastern Brazil ready to check exactly how many tonnes of methane had been saved by capturing the gas seeping from swine, bovine and ovine dung and by turning it into renewable electricity.

The results, as well as the smell, can't have been good.

The reductions estimated at the time of project inception from anaerobic digestion grossly overstated the volume of CO2 saved in the real world.

Developers of Clean Development Mechanism projects in Latin America were in trouble.

Companies such as Dublin-based AgCert had bet the house that they would deliver, selling forward expected Certified Emission Reductions in the marketplace that it later was forced to buy back at much higher prices, bankrupting the company a decade after it was founded in 2012.

There are probably many lessons to learn from AgCert in today's voluntary carbon market, but perhaps one that can be rectified quickly is the cost of verification across multiple sites.

At least that is what today's AI companies are hoping for.

New technologies

An increasing number of developers are putting faith in new technologies to help unlock vast swathes of land for carbon soil sequestration projects from regenerative agricultural practices.

Technologies, such as satellite-based remote sensing and AI modelling, are now key components for many soil sequestration projects in operation or under development, helping to dispel concerns over the measuring and verifying projects made up of large numbers of individual farms cost-effectively, developers say.

It is, proponents say, a much simpler, cheaper and reliable model than turning up to farms on horseback.

"I think these critiques had merit in the past, (but) now AI-enabled ecosystem modelling, satellite-based remote sensing and scaled software platform infrastructures address the historical difficulty, expense, and concerns over accuracy," said Dan Ryan, chief executive of US-based developer CIBO Technologies.

CIBO has a project based in the US undergoing validation under Verra's Verified Carbon Standard using approved methodology VM0042 (Improved Agricultural Land Management), one of 39 developments on the Verra registry currently based on the methodology.

Other companies using the same blueprint include California-based Boomitra, which has projects under development in Africa, India, Mexico and South America, and Arva Intelligence with at least one project in the US.

Both Boomitra and Arva have also developed technologies to assist with the development of their carbon projects.

Arva's AI platform, for example, combines geospatial datasets covering weather, satellite imaging, lidar, field measurements and telemetric data streaming from agricultural equipment to provide what it calls agronomic strategies for farms, not just for carbon sequestration but also crop optimisation, said the company's environmental markets director Audrey Barret Bixler.

Boomitra's founder and chief executive Aadith Moorthy told Quantum that the company uses AI and satellites calibrated with data collected on the ground by its many local partners to measure the soil carbon for its projects.

"What it means is that AI is just a term for building a function which can convert what the satellites see into the realities on the ground. That is what the AI basically does, but the computer learns the function by studying real soil data," he said.

The technology is key to delivering soil sequestration at scale, be it in terms of acres or number of farms.

For example, in India alone Boomitra is working with over 100,000 farmers, while in Mexico they have farms totalling 1.5 million acres in their programme, said Moorthy.

Low hanging fruit

And soil carbon sequestration is big business, with developers attracted by a new wave of low hanging fruit that they believe can save the planet.

Late last year, the EU announced draft rules on certifying on certifying carbon removals, which include soil carbon sequestration, whether by no tilling or other technologies.

To make it verifiable, however, needs cheap verification.

CIBO's Ryan said the technology can accommodate the concept of grouping farms together for the purpose of quantifying carbon sequestration, carbon credits, carbon footprint and carbon intensity.

Arva's Barret Bixler said that the more fields that are enrolled into a project the easier it is to optimise soil sampling strategies.

"Our models are spatial, so we know our uncertainty acre by acre – not just at the scale of the entire aggregation. Statistics tell us that the more acres we average together, the more accurate our estimates will be, but that doesn't mean we are blind to what's happening locally," she said.

Cristine Morgan, chief scientific officer at the Soil Health Institute, a US-based non-profit with a mission to support the enhancement and productivity of soils, said that soil carbon maps based on satellite imagery can provide detailed changes in soil carbon that are "compelling and useful".

But, she added, the validity of claims on accuracy of soil stock predicted depends on the validation methods.

"Whether the validation data used to estimate accuracy were spatially independent and sufficiently cover the feature space," she said.

Morgan also noted that the technologies only see the "top skin of the soil", effectively the soil surface, and need to be able to estimate soil carbon stock at depth – mostly to 30 cm deep sometimes to one metre.

"Soil carbon trends with soil depth vary tremendously with current and historical management and vegetation type – think native grass, versus yard grass, versus trees," she said.

"Then you add all the variations that can happen across 100,000s of field, and wonder how observations could ever train an AI algorithm with all the possibilities," she added.

Credibility

For some, the only way to beat the uncertainties and critics is through on the ground testing.

"For there to be credibility with soil carbon, from what we have seen, there does need to be testing and that's physical testing," said Jim Blackburn, chief executive of US-based non-profit soil carbon standard BCarbon.

"That is actually taking cores and sending those cores to a lab to be tested and that is expensive," he said, adding that he hopes the price will come down as "we learn more".

Blackburn said that carbon done this way currently requires more upfront expense than many of the other types of carbon projects will require, and therefore it will need a higher price.

"I think the buyers will be willing to pay a higher price if they get credibility of the carbon credits," he said.

BCarbon is currently working with about 500 different stakeholders, including both landowners and buyers, and, although mainly US focussed, the standard issued its first overseas credits in July from a project developed by Future Food Solutions in the UK.

Blackburn is not against technology being used for soil sequestration projects, but feels more research needs to be done.

"We would love to come up with a remote sensing that we had a lot of faith in. We are looking at concepts that look at testing 20,000 acres in detail and applying that to an adjacent 100,000 or 1 million acres," he said.

"We are working on concepts like that, but at the moment we are very much committed to each project has a specific testing protocol that has to be followed and that is followed up several years later and the credit that is actually fungible is the difference between the second round of testing and the first round of testing," he added.

Permanence concerns

But even when putting technology and testing regimes to one side, there are some people, as with forest carbon projects, who raise questions over the permanence of the carbon stored in the soil.

Blackburn acknowledges the soil sequestration concept can be difficult to understand, compared with storing carbon in trees, for example.

"Soil carbon is a little bit more difficult for people to grasp. You can't see it. (but) you can see trees (and) you can see coastal wetlands," he said.

"With soil carbon we're talking about carbon that is stored beneath the surface of the earth. Visually it's not there. It's just a step harder just to grasp," he added.

However, criticisms still remain.

"It's really hard and almost impossible to guarantee permanence in forestry, and soil is an entirely different beast and even more complicated," said Gilles Dufrasne, policy officer with Carbon Market Watch.

He noted that carbon market standards try to deal with permanence, particularly whether or not a farmer may decide to use the land for something else, with long-term contracts and insurance.

"But it's still not very credible, even if you have a contract with a landowner that will somehow bind this land to a certain practice for the next 100 years. It doesn't seem realistic that they are able to uphold that contract for two or three generations, Dufrasne said.

He argued that even if permanence for 100 years could be guaranteed, that is "too short to create fungibility" with emissions from fossil fuels that stays in the "atmosphere for hundreds if not thousands of years".

In May last year, a research paper co-authored by David Pannell, professor for Agricultural & Resource Economics at the University of Western Australia, raised a number of concerns with the utility of soil carbon projects, including permanence.

Pannell said that once the carbon has been sequestered into the soil, "keeping it there is not always easy", particularly in Australia, which has regular droughts that would cause carbon to be released.

He noted that methodologies often include a buffer to make up the difference of any credits lost or, in case of the methodology used in Australia, a so-called reversal buffer that reduces abatement by 5% for projects with 100-year permanence guarantees and a further 20% for projects with 25-year permanence.   

The Australian government also offers a 25-year scheme as well as the 100 years, after farmers found the latter unattractive, he said.

For either length the buffer reduces the payments that farmers receive for their carbon projects, Pannell added.

Soil carbon has big potential in Australia, with developer AgriProve expecting to deliver 3 million carbon credits by the end of the decade.

While developers said permanence is clearly a big concern, they added that the issue is important for many carbon crediting projects, not just soil sequestration.

They said that science supports the permanence of carbon sequestered in the soil, and that 'business risks' for projects from farmers deciding to use the land for something else before the crediting period ends are covered by the buffers and contractual provisions.

There is also important work that can be done 'on the ground' to help ensure permanence, they added.

"Perhaps the most important factor for preserving permanence in ag carbon programmes is supporting the growers, especially during the initial years of transition from conventional farming to regenerative farming practices," said CIBO Technologies' Ryan.

"Such support is vital in order to ensure growers don't drop out and reverse the progress that has been made," he said.

CIBO's carbon programme is designed from the "ground up", Ryan said. "To support growers with significant upfront payments-for-practice during early transition years and with ongoing certified agronomist support."

Boomitra's Moorthy agrees that work done on the ground is important to a successful project.

"The key thing to permanence is to make sure you have the right local solutions that can be sustained and people can buy into," he said, adding that it is important to ensure that the financial incentives from the carbon project are appropriate too.

"What is crucial is that the majority of the carbon credit value ends up with the farmer," he said.