Self-purification of the soil: what is it and how is the process, types and main stages

Soil pollution, mainly due to human activities, is now ongoing. But such a thing as self-purification of soils is also known. Consider what it means, the characteristics and ways in which the soil can self-cleanse: aerobic, anaerobic, mineralization, nitrification and humification. As well as the hygienic significance that self-cleaning soil acquires.

Concept and characteristics

When a certain amount of toxic compounds accumulate in the soil, its chemical composition changes, the integrity of the geochemical environment is violated, and microflora is suppressed.From the soil, the accumulated can enter the organisms of animals and people, which leads to a negative impact on he alth.

Self-purification of the soil - its ability to mineralize substances of organic origin, turn them into non-hazardous organic and mineral forms that are absorbed by plants.

In the soil of any type, biological, physical, chemical and other complex processes are constantly going on. Bacteria, protozoa and fungi in the soil can process carbon monoxide, pesticides and other harmful compounds, slowly turning them into non-toxic substances.

Soil animals also take part in self-purification of the soil: insects, earthworms, shrews, moles, they dig passages in the ground and mix it. The rate of purification depends on climate conditions, humidity and temperature - the higher it is, the faster the process goes, therefore, in the southern regions, the earth cleans itself faster.The scale and nature of pollution matter. The degree of drainage, bioactivity and thickness of the humus layer, the ratio of precipitation and evaporation have a significant impact.

Self-cleaning methods

The processing of organic matter into mineral forms takes place in several ways. Each process has its own chemical and biological characteristics and proceeds differently. The decomposition of organic compounds in the soil layer occurs under the action of microorganisms that are in large numbers in it. This natural process can go both aerobically (with the participation of oxygen) and anaerobically, with the help of putrefactive bacteria that do not need oxygen.

Aerobic method

The process occurs under the action of bacteria, with the participation of oxygen. Organics, mainly nitrogen-containing, breaks down into simple mineral compounds. This process is called ammonification, it is characterized by the breakdown of proteins to amino acids, then to hydrogen sulfide, indole, ammonia, skatole, these substances are converted into nitrites, and then into nitrates, which can already be absorbed by plants.The process proceeds with the release of heat, which is absorbed by microorganisms. In parallel with the process of ammonification, humic acids are synthesized, which increase soil fertility.

Anaerobic method

Occurs without the presence of oxygen, organics are also processed by bacteria. The process is reminiscent of fermentation, with the absorption of energy, resulting in the formation of organic alcohols and acids, carbon dioxide, methane, hydrogen and other gases, usually with an unpleasant odor.

Self-cleaning processes

Organics entering the soil are first converted into inorganic compounds and mineral elements, which are then used to feed plants. The rest gradually turns into humus.

Mineralization

This is the process of converting organic compounds into mineral elements. The first stage is the breakdown of proteins, carbohydrates and fats to simpler compounds - respectively, ammonia, carbon dioxide and water, glycerol and fatty acids.

Nitrification

Ammonia is converted to nitrite and nitrous acid, then to nitrate and nitric acid. This process, nitrification, makes nitrogen available to all plants and microorganisms that use it to feed and build cells.

In the soil, the reverse process also occurs - denitrification, this is the result of the activity of bacteria that restore ammonia from nitrates. Denitrification depletes the soil of nitrogen, reducing its availability to plants.

Humification

This is the final stage of the processes of restructuring organic residues into humic substances, the process occurs in the upper layers of the soil. Hummification is a set of biochemical reactions that occur with the help of soil microorganisms, as a result of which specific humic acids, fulvic acids and their s alts, organic acids, fatty acids, carbohydrates and carbon compounds are obtained.Humic acids, as high-polymer compounds, decompose more slowly than other organic compounds, therefore they remain and accumulate in the soil, becoming the basis of humus. The more it is in the soil, the more fertile it is.

The humus formed under the influence of aerobic and anaerobic bacteria and fungi is of great agrotechnical and sanitary importance. Humus does not rot, does not emit an unpleasant odor, does not contain infectious pathogens.

Hygienic value

Soil self-cleaning processes are necessary not only for plant life, but are important for maintaining the he alth of animals and humans. Self-purification begins with the fact that organic residues found in it, together with pathogens, helminth eggs, are filtered and, under the influence of biological, geochemical reactions, are neutralized, destroyed and decomposed. Thus, they lose their ability to infect.Self-purification of the soil reduces the content of infectious pathogens in it, pathogens that are transmitted by contact with the soil, remain on the green parts of plants and on fruits.

Of the two methods of decomposition - aerobic and anaerobic - aerobic is preferable, it proceeds without the release of toxic or bad-smelling gases and substances that degrade the characteristics of water and air. The aerobic method of self-cleaning is typical for well-absorbing air and water, structured soils.

Biodegradation of organic matter by soil populations of microorganisms is one of the main mechanisms of soil self-purification from natural and synthetic compounds constantly entering it. The intensity of mineralization and humification largely depends on the number of biodegrading microorganisms, temperature and soil moisture.

The ability of the soil to absorb and capture organic components, decompose into simple substances and mineral elements is of paramount sanitary and hygienic importance. If the soil did not have this ability, the life of microorganisms and plants in it would become impossible. In order for the self-purification processes to proceed correctly and stably, it is necessary that the supply of organic and synthetic residues does not exceed the capacity of the soil for self-purification. When exceeded, organic matter does not mineralize, but rots, pollutes the soil and air with toxic gases.

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