Earth First

Carbon Farming | Is It Really a Solution?

Carbon farming aims to remove carbon from the atmosphere by storing it in plant material and/or the soil. However, carbon farming is space-limited, easily reversible and hard to measure, so is it really a solution to removing climate change-inducing emissions from our atmosphere?

How does carbon farming work?

Carbon constantly cycles from the Earth into the atmosphere and back again. Carbon can be stored in several ways—in rocks and sediments, oceans, the atmosphere, and living organisms. Some stores, such as in rocks, are long-term forms of carbon capture, while others, such as in living organisms, are short-term. Eventually, stored carbon will be released back into the atmosphere when fossil fuels are burned, animals die, or grasslands and forests that store carbon die and decompose.

Carbon farming has recently been touted as a win-win option for combatting increasing carbon dioxide emissions by increasing agricultural productivity while also removing emissions from the atmosphere.¹ There are two main sectors of carbon storage: biological and geological. Carbon farming focuses primarily on biological, aiming to sequester carbon in soils, grasslands, forests and oceans.²

Carbon farming in practice

One biological practice used to store carbon is agroforestry, which combines trees, crops and livestock on the same land area. With multiple plant species having roots in the ground year-round, plants can continue to draw carbon from the atmosphere and into the land, where other crops can benefit from increased carbon in the soil. This process also helps to decrease greenhouse gas (GHG) emissions from forested ecosystems by discouraging farmers from removing trees and bushes to grow crops. Given that deforestation currently accounts for roughly a fifth of global greenhouse gas emissions, avoiding this can have significant impacts on agricultural GHG emissions.^3,4

A farmer harvests chontaduro fruit, one of the region’s most popular street foods, near El Tambo, Colombia. Chontaduro fruit are often cultivated by smallholders in agroforestry farms in the Pacific lowlands of Colombia. (Photo by Jan Sochor via Getty Images)

Preserving carbon sinks

Other human-driven carbon sequestration practices focus on maintaining biodiverse landscapes. Wetlands, for example, capture carbon through photosynthesis from the plants rooted into them. The carbon captured by plants in wetlands is then passed into the waterlogged soil, where it is stored for longer periods than drier soils.

Plants and crops can also grow faster in waterlogged soil than they can decompose, meaning the plants can capture more carbon over their lifetime than those grown in drier soils. When the plants die and decompose, the carbon stored in their leaves and shoots is trapped in the wetland’s waterlogged soil, creating important carbon sinks.^5,6

Meadows, swales and reed beds make up the Binsenberg peatlands in Germany. Peatlands function as nutrient filters and contribute not only to climate and species protection, but also to improving water quality. (Jens Büttner/picture alliance via Getty Images)

In peatlands, the slow pace of decomposition allows waste to accumulate and form peat, which continues to hold the carbon originally stored in the plants. This produces extremely fertile soils, and in lowland areas, peatlands are perfect for growing vegetables, fruits and cereals. Upland peatlands are often used to graze beef and lamb.

Correctly managed, peatlands can store carbon permanently. However, failure to maintain the sites, either by draining them or ending management practices, can lead to the release of emissions held in the plants and soils. In 2017, drained peatlands contributed five per cent of the EU’s total greenhouse gas emissions.⁷

Despite peatlands only making up 3% of the global land surface, they are believed to store nearly 550 billion tonnes of carbon. That is nearly twice as much as in the world’s forests combined.

Cover crops

Farmers and land managers are, however, more likely to focus on carbon farming processes that aid soil structure and productivity, such as cover crops. These cover crops - such as oats, wheat or turnips - are planted between cash crop seasons and are often not intended to be harvested. The roots and shoots of these cover crops feed soil organisms such as bacteria, fungi and earthworms, adding to the soil’s carbon level over time.⁹

Some studies have shown positive results for cover cropping, finding they did not cause a decline in yields or carbon losses prevalent in other systems, such as organic manure applications.⁹ However, others revealed no significant increase in carbon capture.¹⁰ Scientific consensus is not clear on whether cover cropping has real blanket benefits, but it does indicate that the method’s efficacy depends largely on the site and how well it is managed.¹¹ Cover crops are also suspected to be most effective as a long-term project with plants sown for multiple years in a row.¹² This is because the method often only generates returns after two or three years, but not in the first 12 months.¹³

Do the peaks outweigh the pitfalls?

Carbon farming can be a viable mitigation system to remove carbon from the atmosphere, but critics say it is also a small-scale solution which does little to counteract the long-term problems associated with food sustainability and climate change.¹⁴

The biggest issue with carbon farming is that it can be easily reversed if techniques are not applied continuously over an extended time frame.¹⁵ For example, carbon-rich soils can be ploughed up, and peatlands can be drained, leading to the release of carbon back into the atmosphere.¹⁶

Overgrazing can cause peat hags to form, exposing the peat surface to dry out and blow/wash away. (Wayne Hutchinson via Getty Images)

Carbon farming also only focuses on storing carbon in plants, shrubs, trees and soils. While growing more plants creates more space for carbon sequestration, there is a finite area of land available for growth and, therefore, a finite amount of carbon that can be stored on land. The effects of carbon farming are generally greatest in the beginning, especially in carbon-depleted soils, when most of this space is available. However, research indicates that sequestration plateaus after plants and soils reach their natural level of saturation - usually after 20 to 35 years, depending on the soil type.¹⁷

For carbon farming to be considered a solution to climate change, farmers and land managers must maintain these stores even as their ability to capture new carbon decreases. However, this poses economic challenges as current financial incentivisation models reward farmers only for sequestering carbon, not maintaining the stores—a practice key to the viability of carbon farming.

Heyang Yellow River Wetland Nature Reserve, where in recent years the local government has carried out the work of "returning farmland to water and wetlands". (CFOTO/Future Publishing via Getty Images)

Costs for farmers

The EU and Belgian organisation Soil Service has said it will pay farmers to follow carbon farming techniques based on actions taken between an initial carbon measurement and another taken at a later date.¹⁸ The Soil Service uses the Verified Carbon Standard, a system administered by the non-profit organisation VERRA that certifies carbon emissions reductions, to measure the carbon sequestered and sell carbon credits.

However, there are some risks associated with using this method of paying based on the amount of additional carbon stored between measurements. Helena Vanrespaille, a researcher at the Soil Service Belgium, described the method of paying on the premise of visible change as “risky” because there is a possibility that “the second measure will not show enough carbon storage to justify the payments that have been made in the meantime”.

While it can help some farmers in transition, it can also incidentally punish farmers who have adapted to store more carbon earlier and, as a result, already have high carbon storage in the soil, she explained. There are also other problems, including the difficulty of accurately measuring the efficacy of carbon farming itself. This is because the effects are easily reversed, and accurate measurement relies on knowing how much carbon the plants were storing before carbon farming practices were applied.¹⁶

Therefore, scientists must interpret carbon storage numbers conservatively, often relying on lower estimates of the possible carbon stores. This makes it difficult to place a true value on the efficacy of carbon farming and undermines attempts to financially incentivize farmers and land managers to follow the practices.

Should carbon farming be our focus?

Carbon farming is already widely pushed as a viable method of carbon capture in Belgium, France and Germany, but many scientists see it as “part of the solution” rather than a silver bullet.¹⁹

Payment systems which financially reward carbon sequestration need to be improved to prevent farmers from being forced to front investment in carbon farming practices before there is any possibility of return. Affordable and efficient technology capable of measuring and tracking carbon capture must be rolled out widely to help tackle this issue, or a lack of accurate measures will remain a barrier to wider uptake. Additionally, current systems still rely heavily on farmers to bear the brunt of the costs associated with the transition to climate-positive practices.²⁰ However, action is needed at all stages of the food value chain to make carbon farming a viable solution.

Eric Toensmeier, Director of Perennial Agriculture Institute, told FoodUnfolded that carbon sequestration is “an important part of mitigation” but admitted it “cannot do the job alone”. He said “many practices are already quite widely adopted and growing quickly” but warned the changes are “not at the scale or pace needed without some big policy changes.”

“It is potentially reversible if there is a change back to carbon-unfriendly farming or climate change brings intense prolonged drought or intense fire. We cannot rely on it alone.”

Meanwhile, Vanrespaille said carbon farming was an important “part of the solution” but only if “done well”. She said, “Carbon capture is the only way to reverse the historical emissions of carbon and carbon farming will play a part in facilitating that. However, it must be emphasised that we have to cut our carbon emissions, otherwise carbon farming will be like filling a bucket full of holes. I expect that within a decade, farmers will be fully aware of carbon farming and be talking about carbon storage and discussing the price of a tonne of carbon as part of their work.”