Minimal improvements to agricultural soils around the world would store enough carbon to keep the world within 1.5C of global heating, a new study suggests.
Farming techniques that improve long-term fertility and yields can also help to store more carbon in soils but are often ignored in favour of intensive techniques using vast amounts of artificial fertilizers that can increase greenhouse gas emissions.
Using better farming techniques to store 1% more carbon in about half of the world’s agricultural soils would be enough to absorb roughly 31 gigatonnes of carbon dioxide a year, according to the new study. That amount is relatively close to the 32 gigatonnes gap between current planned emissions reduction globally per year and the amount of carbon that must be cut by 2030 to stay within 1.5C.
The estimates were calculated by Jacqueline McGlade, the former chief scientist at the UN environment programme. She concluded that storing more carbon in the top 30cm of agricultural soils would be feasible in many regions where soils are currently degraded.
McGlade now runs Downforce Technologies, which is a commercial organization that sells soil data to farmers. The company uses publicly available global data, satellite images and lidar to assess in detail how much carbon is stored in soils.
“Outside the farming sector, people do not understand how important soils are to the climate,” said McGlade. “Changing farming could make soils carbon negative, making them absorb carbon, and reducing the cost of farming.”
The data Downforce collects could also allow farmers to sell carbon credits based on how much additional carbon dioxide their fields are absorbing. For a long time, soil has been known to be one of the Earth’s largest stores of carbon, but until now it has not been possible to determine in detail how much carbon soils in particular areas are locking up and how much they are emitting. According to the UN, 40% of the world’s farmland is degraded.
Arable farmers could store more carbon within their soils by changing their crop rotation, planting cover crops such as clover, or by using direct drilling, which allows crops to be planted without the need for ploughing.