After the oceans and fossil fuels, soils represent the largest reservoir of carbon on earth.
That’s why when it comes to climate change the answer lies beneath our feet; nearly ten billon tonnes of carbon are stored in the UK’s soils alone – equivalent to the global emissions emitted by all of humanity in one year. And there’s space for a lot more to be sequestered, especially if we are to hit net zero emissions by 2050, or earlier.
Around the world, billions of pounds are being invested in fancy new machines that capture carbon from the atmosphere.
From Climeworks in Switzerland, which employs a reusable membrane to capture carbon dioxide pulled through machinery by fans, to Canada’s Carbon Engineering, which is turning Co2 into a useful fuel. However, many are overlooking the humble British farmer.
Covering nearly three-quarters of the UK countryside, farming has more potential than any other industry to do just that – farm carbon – by changing land use, erosion control, low or zero tillage, adding organic matter, rewetting drained land and better crop management, as just a few examples. If we paid farmers directly to start using their land to sink carbon, everyone could be a winner.
“The UK has some of the best farming soils in the world. Putting more carbon into the ground and into vegetation improves critical soil health, boosts natural nitrogen and carbon cycles. Production is gentler and moves us towards more climate resilient and sustainable agriculture. It makes a lot of sense,” explains Jason Hayward-Jones, director at regenerative farming and software company, Regenfarm.
It’s why boosting soil carbon is starting to gain a lot of attention. A report from the Committee on Climate Change, which advises the UK government on climate, now demands a radical shift in land use, mentioning soils over a hundred times. The report says that nearly two-thirds of emissions from the land sector could be cut by 2050 without hampering food production, and recommends transforming one-fifth of the UK’s farmland into landscapes focused on storing carbon.
The UK’s agriculture sector is a big emitter, accounting for nine per cent of the country’s emissions. But soil carbon levels in farmland are declining: we’ve lost 84 per cent of fertile topsoil since 1850, and erosion continues at up to three centimetres a year in some areas. It doesn’t help that soils are highly sensitive to climatic extremes. So, what can we do to turn the tide?
“It’s a massive challenge. We didn’t know much about soils 15 years ago, now we know so much more. What we do know is that farmers need to be the arbiter of change and in the driving seat on this issue, if we don’t bring them along with us we cannot achieve anything,” explains Sam Packer, policy officer for farming and land use at the Soil Association.
As a consumer, buying organic food helps as organic soils contain up to 3.5 tonnes more carbon per hectare than non organic soils. Not forgetting that nitrogen fertilisers used in non-organic farming also produce nitrous oxide, a potent greenhouse gas. Yet despite the benefits of greenhouse gas mitigation, only three per cent of farmland in the UK is organic.
In a post-Brexit world, farmers could well be paid for farming carbon, under the so-called ‘public money for public goods’ scheme, set to replace EU subsidies. There is now a move, via the government’s Agriculture Bill, to incentivise farmers to improve soil health, which would naturally involve more carbon capture and storage.
The UK has already committed to the global four per 1,000 soil carbon initiative, aimed at increasing soil organic carbon by 0.4 per cent each year. But none of these initiatives will be effective without the ability to measure soil carbon and how farmers are managing it.
“Today we have the technology to prove what is going on with carbon in farming down to the field level. With the launch of the Sentinel-6 satellite, the resolution will be down to centimetres. Precision agriculture will reach new levels,” says Hayward-Jones.
Then there’s the growing sector of carbon markets, which could allow British farmers to ‘sell’ the carbon they capture by growing trees, protecting peat bogs or boosting soil carbon in the form of verified carbon credits.
One of the biggest potential areas for carbon sequestration in farming is through an agro-ecological approach to the landscape, where ecological concepts and principals are applied to agriculture, including bringing more trees into the picture, either through reforestation or agroforestry.
Turning grassland into forest means soil carbon stock goes up by 25 tonnes per hectare, on top of the large amounts of carbon that are stored in trees themselves. “Right now, integrating trees is what farmers are most excited about, they also make the landscape more resilient to the ravages of climate change,” explains Packer.
Certainly, there is no quick fix solution, but any practice that boosts soil health and in turn builds carbon stocks in our depleted soils is welcome. The big question is whether transforming landscapes to tackle climate change will be to the detriment of local food production.
According to the Committee on Climate Change, this doesn’t have to be the case, providing we move towards healthier diets, slash production of the most carbon-intensive foods, reduce food waste and boost forest productivity.
It is also worth thinking about the bigger picture when it comes to land use. The UK has a lot of peatland, which are immense stores of carbon.
“The picture in the UK is nuanced and complex. Peatlands are a huge carbon store, but only 20 per cent are in good condition. They should be a priority and turned more quickly into carbon sinks, not emitters, [by] overstocking with livestock, draining for farming and use for intensive production,” says Packer. “We need to do a lot, lot more.”