Carbon Cycle

Why is carbon such a big deal, and what does it have to do with soils?

Did you know that over 2,700 Gigatonnes (Gt) of carbon is stored in soils worldwide?!? This is more than the carbon in all of the plants in the world, AND in the atmosphere! Because Carbon is so important to live on earth, the soils play an important role in the global carbon cycle.

harvest carbon sunset


All living things are made of carbon. When animals, bacteria, and other living organisms breathe out, their breath is filled with carbon dioxide. The carbon dioxide is taken out of the atmosphere by plant photosynthesis. This helps plants to grow.

When these plants grow, they create new leaves, roots, and shoots. At the end of the season, leaves fall to the ground, and turn into different types of soil organic matter (see the soil biology page).  This dead organic matter creates food for microbes, which respire and create carbon dioxide back to the atmosphere. When plants or the soil are burned, this also releases carbon dioxide into the atmosphere.

In the soil, there are two major types of soil carbon. Biomass, which is the living bacteria and fungi, and non-biomass carbon, which is the cellulose, starch, and lignin in dead plants. Some of these bind soil particles together into soil structure. 


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