More carbon resides in soil than in the atmosphere and all plant life combined
There are 2,500 billion tons of carbon in soil, compared with 800 billion tons in the atmosphere and 560 billion tons in plant and animal life.
Soil organic carbon (SOC) is a measurable component of soil organic matter. Organic matter makes up just 2–10% of most soil’s mass and has an important role in the physical, chemical and biological function of agricultural soils.
Sequestering carbon in SOC is seen as one way to mitigate climate change by reducing atmospheric carbon dioxide. The argument is that small increases of SOC over very large areas in agricultural and pastoral lands will significantly reduce atmospheric carbon dioxide.
It has been estimated that agricultural soils have lost 42–78 Pg of carbon relative to their pre-agricultural state. The transfer of soil organic carbon to the atmosphere is a major driver behind the climate change, but also represents an opportunity for managing current greenhouse gas emissions through carbon sequestration.
The loss of SOC has negatively affected soil health and increases our reliance on inorganic fertilizers to maintain crop productivity.
A large number of soil functions that are critical for crop and pasture production, including nutrient and pH buffering, water retention, soil structural stability, and higher agronomic efficiency with related to soil’s capacity to exchange nutrients are all positively associated with greater SOC levels.