Carbon (C) is one of the most important elements in our world because it is used as a source of energy for almost every living organism. If it were not for carbon and some other elements, there would be no life on our planet at all.
The carbon content in the human body is about 20%, and for plants it is about half of the mass. Each organism uses carbon in different ways, but mostly for energy.
In soil, carbon plays a huge role and directly affects soil quality and fertility. Therefore, it is important to understand such important processes as carbon cycling in the environment.
One of the most common studies of carbon in soil is the determination of organic matter. It is known that carbon makes up about 58% of soil organic matter (organic carbon). It is formed in the soil during the decomposition of organic materials and the remains of living organisms. Carbon can also be found in inorganic minerals (most often carbonates).
Stable carbon (or stabilized carbon) is carbon that can be counted on for decades to centuries. In other words, stable carbon is a fraction that is formed by microbial activity and is constantly present in the soil. The activity of carbon in the soil is driven by the activity of microorganisms that use it for food and energy (since stable carbon is the most accessible source of carbon for microbes).
One of the tests for determining stable carbon is related to soil particle size. To perform this analysis, a very fine sieve (53 microns or 0.053 millimeters in pore size) is used to sift slightly moist soil through. Everything that is sifted through this sieve is so fine that it is the same size as the smallest soil particles, such as silt and clay. The stable carbon bound to these smallest particles is also sifted through the sieve.
In order to understand how carbon is stored in the soil, the organic carbon content of the soil is analyzed. The product of the percentage of organic carbon and the bulk density of the soil is equal to the amount of carbon stored:
C = С org∙ ρ ∙ h
C – Amount of accumulated carbon (by volume), C organic – Organic carbon (%), ρ – Bulk density of soil (g/cm3), h – Depth (cm).