Carbon Cycle

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Soil Microbiology Nature of Soil Soil Habitats (Lithosphere) Microorganisms in Soil Decomposition of Organic Matter in Soil Bacteria in Soil Physiological Types of Bacteria in Different Soils Fungi in Soil Protozoa in Soil Algae in Soil Viruses in Soil Functions of Microorganisms in Soil Humus Functions of Humus Cycles of Elements Carbon Cycle Nitrogen Cycle

Carbon Cycle

	Carbon Cycle -About half of the dry weight of living organisms is composed of carbon. The ultimate source of organic carbon compounds in nature is the carbon-dioxide present in the atmosphere. Carbon dioxide is the most oxidized state of carbon, and is reduced primarily by photosynthesis. Some amount of carbon dioxide, derived form dissolution of carbonates and bicarbonates, is utilized by certain chemolithotrophs.
Carbon dioxide is also fixed by heterotrophs in preformed organic compounds. Thus carbon dioxide in these processes is transformed into various cell components like organic carbon (carbohydrates, proteins, fats, nucleic acids, etc.). The small amount (0.3 percent) of carbon dioxide in the air will all get exhausted if it is not cycled back. Some of this comes back to the atmosphere by way of respiration, but mainly by decomposition, and this is accurately microbial decomposition.
Microorganisms play an important role in the decomposition of the dead tissues of plants and animals deposited in the soil. All organic compounds, with few exceptions, are decomposed by microorganisms
Charcoal, graphite, diamonds, etc., though oxidizable, are not decomposed by microorganisms, probably because they cannot be dissolved in anything and thus brought into the cell for oxidation. Under aerobic conditions organically bound carbon is ultimately released as carbon dioxide by microbial decomposition.

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Sulphur Cycle Ammonification in Soil Nitrification in Soil Nitrate Reduction in Soil Denitrification in Soil Nitrogen Fixation Symbiotic Nitrogen Fixation Rhizobium Specificity of Bacteria and Legumes Non-Symbiotic Nitrogen Fixation Non-symbiotic Nitrogen Fixing Microorganisms Mechanism of Nitrogen Fixation Oxidation of Sulphur and Sulphur Compounds by Bacteria