Huge amounts of carbon dioxide are stored in soil and more could be added. All that is needed is a change in the way soil is managed on farms and in gardens.
What is exciting is that it can be done today without the need for new technology to be developed or massive new machines to be built. It just needs is farmers to change the way they treat soil. Not only could that help to take CO2 out of the atmosphere and store it in soil it would also reduce fertiliser and pesticide use which means less the chemical leaching into rivers and streams. See this article about extreme levels of pollution in Europe.
There are several new books explaining how we could sequester enough CO2 to make a huge difference to climate change:
“According to Dr. Rattan Lal of Ohio State University, a pioneer in the study of “biosequestration” (using plants and microbes to sequester carbon dioxide), humans have put some 500 gigatons (billion tons) of carbon dioxide into the atmosphere since the birth of agriculture some ten thousand years ago. But most of that CO2 was emitted during the relatively recent advent of modern agriculture. Through plowing the land, which releases tremendous quantities of CO2, deforestation, urbanization, and land-use change we have effectively taken a massive quantity of carbon that used to be stored in the ground and released it into the atmosphere.”
[Tickell, Josh. Kiss the Ground (p. 18). Atria/Enliven Books. Kindle Edition.]
Small scale commercial growers and gardeners can help by not digging or rotovating their soil. For gardeners switching to no-dig beds is the best way to start. In 2010 I started a trial garden on farmland that had not been cultivated for around 30 years. No digging was involved and it worked.
The other parts of the process are the application of organic matter, compost and yet more compost! Next is not leaving the soil bare particularly in winter when heavy rain causes compaction and washes out nutrients.