Humus

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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

Humus

	Humus - A precise definition of humus is rather difficult. Humus is a mass of resistant residual organic matter formed as a result of decomposition and synthesis of organic matter under soil conditions. It is generally a brownish black waxy material, known as the fat of the land. It varies greatly in composition, which depends upon the following factors.
1. The materials from which it is made constituents of dead and living plant, and animal cells. 2. The interconversion of material by the agency of various types of microorganisms. 3. The environmental condition under which the organisms are working temperature, moisture aeration, soil reaction, etc. Humus is then a very complex and variable material.
It is mainly composed of compounds of carbon and nitrogen. This combination is called ligno protein. Besides this, it also contains number of inorganic salts such as phosphates, potash, etc.

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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