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Soil carbon is present in two forms: inorganic and organic. Soil inorganic carbon consists of mineral forms of carbon, either from weathering of parent material, or from reaction of soil minerals with atmospheric CO 2. Carbonate minerals are the dominant form of soil carbon in desert climates. Soil organic carbon is present as soil organic matter.
This is 3.3 times the amount of the atmospheric pool at 750 gigatons and 4.5 times the biotic pool at 560 gigatons. The pool of organic carbon, which occurs primarily in the form of SOM, accounts for approximately 1,550 gigatons of the total global carbon pool, [14] [15] with soil inorganic
Soil aggregation can physically protect organic carbon from decay by soil microbes. [19] More aggregate formation can result in more soil carbon storage. There is much evidence that arbuscular mycorrhizal fungi increase soil aggregate formation, and that aggregate formation may be mediated by the arbuscular mycorrhizal protein glomalin. [20]
Organic farming in particular emphasizes optimal soil management, because it uses soil health as the exclusive or nearly exclusive source of its fertilization and pest control. Soil management is an important tool for addressing climate change by increasing soil carbon and as well as addressing other major environmental issues associated with ...
Carbon is its key component comprising about 58% by weight. Simple assessment of total organic matter is obtained by measuring organic carbon in soil. Living organisms (including roots) contribute about 15% of the total organic matter in soil. These are critical to operation of the soil carbon cycle. What follows refers to the remaining 85% of ...
In general, organic matter contacting soil has too little nitrogen to support the biosynthetic needs of the decomposing soil microbial population. If the C:N ratio of the decomposing organic matter is above circa 30:1 then the decomposing microbes may absorb nitrogen in mineral form as, e. g., ammonium or nitrates. This mineral nitrogen is said ...
When the organic component of a soil is substantial, the soil is called organic soil rather than mineral soil. A soil is called organic if: Mineral fraction is 0% clay and organic matter is 20% or more; Mineral fraction is 0% to 50% clay and organic matter is between 20% and 30%; Mineral fraction is 50% or more clay and organic matter 30% or ...
Part of the net primary production, or the remaining carbon absorbed by the biosphere, is emitted back into the atmosphere through fires and heterotrophic respiration. The rest is converted into soil organic carbon, which is released more slowly, or "inert" dissolved carbon, which can remain in the biosphere for an unknown period of time. [3]