Example
Land management can influence organic carbon inputs and losses.
The catch
Increases may saturate or reverse, and measurement can be difficult.
Related terms
Afforestation, Biodiversity, Blue carbon, Carbon sink, Carbon stock, Deforestation
In more depth
Soil carbon, explained.
Soils store more carbon than plants and the atmosphere combined, so small changes across large areas matter for the climate. Cover crops, added compost and trees integrated into farmland can raise soil carbon, while ploughing and drainage tend to release it. Reduced tillage is a case of contested evidence, since it often moves carbon towards the surface and deeper samples can show little net gain.
Sampling design decides whether a change can be detected, because carbon varies widely across a single field and changes slowly relative to the stock. Careful projects sample to a stated depth, measure soil density as well as carbon concentration and return to the same points. Side effects count too. Extra fertiliser that boosts plant growth can raise nitrous oxide emissions and cancel part of the gain. Credits for soil sequestration also need rules for what happens if the farmer changes practice.