Soil Nutrient Cycling
Carbon Cycle
Carbon is one of the basic building blocks of life and the most abundant element in organisms, accounting for about half of typical dry biomass. Carbon is an integral component of every life form on earth from proteins and lipids to even our DNA. Furthermore, all known life on earth is based on carbon. Carbon can be stored in a variety of reservoirs, including plants and animals, which is why they are considered carbon life forms. Carbon is used by plants to build leaves and stems, which are then digested by animals and used for cellular growth. In the atmosphere, carbon is stored in the form of gases, such as carbon dioxide. It is also stored in oceans, captured by many types of marine organisms. Because Earth is a closed system, the amount of carbon on the planet never changes. However, the amount of carbon in a specific reservoir can change over time as carbon moves from one reservoir to another. The movement of carbon from reservoir to reservoir is known as the carbon cycle. Soil represents a reservoir able to both store and release carbon within the global carbon cycle and as such is considered both a sink and source for carbon.
Agriculture’s Role in the Carbon Cycle
While the agricultural sector has the ability to impact the carbon cycle on a large scale, often through the release of carbon, farmers have a vested interest in retaining and increasing soil organic carbon. Soil management plays a critical role in whether the carbon remains in the soil or is released to the atmosphere. Agricultural practices can impact both the amount and the composition of soil organic carbon and hence also the soil’s physical, biological, and chemical condition.
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