According to a researcher who specializes in environmental issues, this could make it a key tool in the fight against climate change.
Usually soil below the surface is the highest in organic carbon because the carbon is put into the soil by plant roots. Soils high in organic carbon look dark brown and crumbly (like a good cake).
“The soil stores three or four times as much carbon as the atmosphere contains,” said Dr. Rob Jackson, a professor at Stanford University who recently lectured at Utah State University. “The things we do to alter our soils, and especially to lose organic matter through agricultural practices, have released a lot of carbon to the atmosphere. They also provide an opportunity to restore that carbon.”
According to research by the International Soil Resource Center, human agriculture has caused the loss of 130 billion tons of carbon from soils globally. Soil carbon can be lost when the carbon is exposed to the air, allowing microbes to break it down. Ploughing is a major culprit, but Jackson thinks with the proper incentives, soil carbon could be restored.
“A really important role for soils in climate change is to restore carbon that’s been lost through ploughing and other practices," he said. "One thing we can do that is already done in some places is to provide incentives to take land out of ploughing. Western Canada, for example, has had programs to actively pay farmers to put carbon back into the soil through multi-cropping, nitrogen-fixers and fallow programs. So there are places in the world where these incentives are already happening.”
The benefits of restoring soil carbon don’t just extend to fighting global warming. Soils high in organic carbon are better for agriculture. They need less irrigation and fertilization because they hold more water, nitrogen and phosphorus. And they seem to prevent erosion because their granular structure keeps soil from being blown away.
“It’s not just about restoring carbon as an element. Restore soil carbon and we gain multiple benefits,” Jackson said.
Soils hold more carbon than all the world's vegetation and the atmosphere combined. For thousands of years, human activities — especially the conversion of forests and grasslands to cropland — have released vast amounts of this stored carbon into the air as carbon dioxide (CO₂), contributing significantly to global warming. The good news? We can reverse much of this damage by actively putting carbon back into the soil through smarter land management practices.This process, known as soil carbon sequestration, involves capturing atmospheric CO₂ through plants and storing it long-term in the soil as organic matter. It is one of the most natural, cost-effective, and multi-benefit strategies available for mitigating climate change.How It WorksPlants absorb CO₂ from the air during photosynthesis. When they die or shed leaves and roots, this carbon enters the soil. With the right practices, microbes and soil structure help lock it away instead of releasing it back into the atmosphere. Healthy soils rich in organic carbon act like a sponge — improving water retention, nutrient availability, and resilience to drought and erosion.Proven Practices That Build Soil CarbonSeveral well-established methods can increase soil carbon levels:
Reduced or no-till farming — Minimising soil disturbance keeps carbon from being exposed and oxidised.
Cover crops — Planting crops like clover or peas between main harvests adds biomass and keeps living roots in the soil year-round.
Crop rotation and perennial crops — Diversifying plantings and using deep-rooted perennials enhances carbon storage.
Compost, manure, and biochar application — Adding organic amendments feeds soil microbes and directly boosts carbon content.
Agroforestry and regenerative grazing — Integrating trees, livestock, and crops creates systems that continuously build soil health.
Studies show that widespread adoption of these practices on global croplands could sequester up to 1.85 gigatons of carbon per year — roughly equivalent to the annual emissions of the entire global transportation sector.
news.climate.columbia.edu
Multiple Benefits Beyond ClimatePutting carbon back in soil is not just about reducing greenhouse gases. Healthier soils lead to:
Higher crop yields and better food security
Improved water quality and retention (reducing flood and drought risks)
Greater biodiversity in soil microbes and above-ground ecosystems
Reduced need for synthetic fertilisers and lower overall farm costs in the long term
These co-benefits make soil carbon strategies a "no-regret" option that benefits farmers, ecosystems, and society simultaneously.
unep.org
Relevance to South African AgricultureIn South Africa, where the pecan nut industry is expanding rapidly, there is exciting potential. Pecan orchards — especially when managed with cover crops, minimal tillage, and regenerative practices — can sequester significant amounts of carbon in both tree biomass and soil. Young orchards, in particular, show strong gains in soil organic carbon and biological health compared to traditional annual crops like cotton.With favourable growing conditions and a focus on quality, South African pecan producers are already contributing to a more sustainable agricultural future. Practices such as inter-row cover crops and reduced soil disturbance align perfectly with the goal of building soil carbon while maintaining high yields and export-quality nuts.Realistic ExpectationsSoil carbon sequestration is a valuable tool, but it is not a complete solution on its own. It can complement — but not replace — deep cuts in fossil fuel emissions. Carbon stored in soil can sometimes be released again if practices change or extreme weather events occur, so long-term management is essential. Still, even modest increases in soil carbon across millions of hectares can make a meaningful difference.The Way ForwardGovernments, farmers, and researchers worldwide are increasingly supporting carbon farming initiatives. In South Africa and beyond, shifting toward regenerative agriculture offers a practical path to fight climate change while revitalising degraded lands and supporting rural economies.By putting carbon back where it belongs — in the soil — we can create healthier farms, more resilient food systems, and a more stable climate.
Measuring soil health through carbon dioxide flush
