Humification: Definition, Process and Sample Questions

Humification is one of the significant five steps of the decomposition process. Decomposition is done by several microorganisms and organisms; they are called decomposers. Decomposers break down complex organic matter into simpler subunits, i.e., inorganic matter such as carbon, oxygen, nitrogen, phosphorus, etc. This process of breaking down complex matter into simpler subunits is termed as decomposition and is carried out in five steps, one of them is humification. This article comprises all the important concepts related to the topic humification and the questions frequently asked.

Keyterms: Ecosystem, Soil, Organisms, Decomposers, Bacteria, Fungi, Enzymes, Nutrients, Carbon dioxide, Water, Decomposition, organic substances, Fallen leaves, Animal wastes, Humification

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What is Decomposition?

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Decomposition is defined as the biological process of breaking down complex organic matter into simpler inorganic subunits such as Carbon, nitrogen, oxygen, phosphorus, potassium, etc.

• Decomposition is carried out by several microorganisms, and organisms, they are called decomposers.
• The complex organic matter which usually undergoes decomposition comprises dead plants, dead leaves, fecal matter, dead flowers, they are termed as detritus.
• Decomposition is carried out in five steps:

1. Fragmentation: Several organisms break down the waste material into smaller fragments, this process is called fragmentation, the organisms which result in fragmentation are called detritivores.
2. Leeching: Leeching is the process by which the water-soluble sub-units dissolve into water and moves down the soil horizon, finally accumulating as salts.
3. Catabolism: Bacterial and fungal enzymes result in the breakdown of the complex material; this process is called catabolism. Humification and Mineralisation take place in the soil
4. Humification: Humification is the process of formation of dark amorphous matter called humus. Humus is highly resistant to microbial decomposition and thus, doesn’t break down easily.
5. Mineralization: When humus is broken down into inorganic nutrients by the microbes, into simpler units it is called mineralization.

• Decomposition requires proper environmental conditions and a good supply of oxygen to ensure the proper decomposition of organic matter into smaller sub-units. The rate of decomposition also varies according to the composition and nature of matter to be decomposed. For example, substances rich in lignin, and chitin take a longer time to decompose, as compared to substances rich in nitrogen, or water-soluble sugar.

Decomposition

Read More: Mineralisation

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What is Humification?

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Humification is defined as the process which involves the formation of humus. Humus is a black amorphous (not having a definite shape or structure) substance produced by the decomposition of dead and decaying organic matter, detritus, by microorganisms.

Humification is a different process as compared to mineralization. In mineralization, as the name implies, inorganic nutrients are recycled. These inorganic nutrients are obtained by the decomposition of the humus formed earlier. Organic matter is further decomposed to form inorganic simpler compounds, such as carbon, nitrogen, phosphorus, which are easier for other microorganisms to use.

In the process of humification, complex organic matters are transformed into organic polymers. These organic polymers are stable and cannot be decomposed easily and rapidly further by organisms and thus remain as humus for a prolonged period of time.

Humification

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Process of Humification in Soil

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Soil formation takes place in three steps:

1. weathering of rocks,
2. humification of plant remains and
3. lateralization.

In the humification process, humus is produced by decomposition of wood, plant twigs, etc. Humus is a black amorphous (not having a definite shape or structure) substance produced by the decomposition of dead and decaying organic matter, detritus, by microorganisms.

Process of Humification in Soil

Humification affects the soil quality, along with its color and texture. Soil rich in humus is usually black in color or even dark brown. Humification also determines the water content of the soil. Humus acts as a binder and helps in binding soil particles together. Humification maintains the optimum pH of the soil, which is essential for the growth of microorganisms. Humus also increases soil fertility and the organic content of the soil. 

Read More: Fragmentation

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Things to Remember

Humus can be formed by any one of the following methods:

• Plant remains are decomposed constantly by oxidation, in the constant presence of oxygen. Oxygen is added from groundwater present below the soil.
• Lignin and other organic substances present in the plant cells, fibers, etc. are converted to humus by microorganisms and fungi, and such components prolong the process
• Cellulose and hemicellulose are readily decomposed to humus, due to the simpler nature of sugar.
• Depolymerisation of polysaccharides and complex carbohydrates occurs instead of degradation
• Hemicellulose and other constituents of the cell wall are easily and quickly converted to glucose or other sub-units such as fructose, galactose, etc.
• Degradation of lignin results in various carboxylic acid formations in the sub-units
• Peat formation depends on various climatic factors, e.g., temperature, pH (Acidity and basicity of the soil), moisture content, minerals present, etc.
• The humification process can be accelerated by adapting the process of vermicomposting.

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