Many people have to deal with this concept, but not everyone knows what humus is. Translated from the Latin language, “humus” means “earth”, “soil” and is the main organic substance containing nutrients that are simply necessary for plants.
Humic substances, on the other hand, belong to a special group of chemical compounds characteristic of the earth's soil cover, that is, they are specific only to the soil. Surely, what is humus, now it has become clear, and from what is it formed? From the remains of plants, animals and microbes as a result of interaction with various components of the environment.
The chemical composition of humus is rather complicated. It is characterized by a dark color, which is absent in plants. The humus contains very valuable humic acid, which contains a lot of carbon (about 60%), oxygen (about 35%), nitrogen (5% on average), phosphorus, sulfur, iron and so on. Based on the foregoing, another answer to the question of what is humus follows. Humus is a term that combines a huge complex of chemicals containing in its composition an organic part (humic and fulvic acids), an inorganic component (chemical elements of inorganic origin, or, in other words, minerals, which are among humates and fulvates). But we’ll talk about this in more detail now.
How is humus formed?
You have already familiarized yourself with the concept of humus; the next open question is what is soil humus, and how is it formed? The humus of the soil is nothing but the product of the vital activity of various organisms, primarily earthworms. The process of humus formation is long-term.
Vegetation, metabolic products, animal remains - all this is food for organisms that live in the soil. Some part of all of this is amenable to mineralization, and the other, to biochemical enzymatic decomposition and oxidation (humification), during which the synthesis of organic compounds takes place, and humus is formed. Humus prevails in it, as well as humic acids, which are converted over time, resulting in oxidation to carbon dioxide and water. It is very important that the ways of humus transformation - mineralization or humification - depend directly on soil and climatic conditions. In fairly warm and humid climates, the oxidation process occurs very quickly, and almost the entire litter of vegetation is mineralized, which prevents humus from accumulating in the soil. In cold climates, the transformation of litter is slightly slowed, and their number is small, as a result of this, the humus content in the soil is small. Optimal for humification are moderate climates without waterlogging.
So, from the foregoing, we can draw the appropriate conclusions:
- to get a good crop, the plant just needs carbon dioxide;
- Carbon dioxide in the soil, as a rule, is formed as a result of decomposition of the remains of plants, animals and microbes when interacting with various components of the environment (microorganisms, insects, worms, fungi, and so on);
- processed organic residues of plants, animals and microbes form humus humus, which is an essential component of soil fertility.
Humus function
- Physical function. It creates a solid soil structure, due to which a favorable circulation of water, air of the required temperature is ensured and good root growth in the soil is predetermined. Humus also promotes cohesion to light soils and loosening of dense soils.
- Chemical function. It is an excellent repository of nutrients. As a result of the activity of various microorganisms, humus decomposes over time (mineralization process), as a result of which the nitrogen, phosphorus, potassium and other elements contained in it are released.
- Biological function. Humus creates favorable conditions for the development and further activity of various microorganisms.
Humus types
- Pestilence (humus podzolic soil). Humus of this type is very coarse, containing a large amount of detritus, which forms at low biological activity under the condition of an acidic reaction of the medium.
- Moder (humus of sod-podzolic soil), which forms under medium biological activity under the condition of an acid reaction of the medium and weakly interacts with the mineral part of the soil.
- Mull (humus of chernozems), formed at very high biological activities under the condition of a neutral reaction of the environment, actively interacting with the mineral part of the soil.
- Anmoor (humus of soddy-gley soil), which forms in temporarily moistened soils.
- Aligotrophic peat, which is the “poor humus” of high bogs.
- The last type is eutrophic peat, which is a "rich humus" of lowland marshes.
The value of humus in soil fertility
Humus is actively involved in the process of soil formation. He plays the most important role directly in the formation of the soil profile. Humus promotes the bonding of soil particles into aggregates (lumps), creates valuable agronomic structures and physical properties of the soil favorable for plant life. It contains the basic nutrients for plants and various trace elements that become available to plants after the mineralization process.
Humic substances are food for soil microorganisms. The intensity of various chemical and biological processes that determine the accumulation of substances necessary for plants depends on the humus content in soils. Humus also contributes to darkening the soil, thus the earth absorbs solar energy better.
Composition and properties of humus
This fertilizer is a complex dynamic complex of organic compounds that are formed during the decomposition of various organic residues.
As part of the soil humus, a specific part (approximately 90%) consisting of humic substances and a non-specific part (the rest) consisting of non-humified organic substances can be distinguished. Humic substances of soils, in turn, are represented by:
- humic acids - high-molecular nitrogen-containing organic compounds that have a cyclic structure, insoluble in water and acids, but soluble in weak alkalis, humic acids include carbon (about 50%), hydrogen (5%), oxygen (40%), nitrogen (5%);
- humates formed as a result of the interaction of humic acids with the mineral part of the soil; humates of alkalis are highly soluble in water, thereby forming colloidal solutions; humates of calcium and magnesium are not soluble in water, form a water-resistant structure;
- fulvic acids - high molecular weight nitrogen-containing organic acids that dissolve in water, various acids and alkali solutions, in addition, they are able to dissolve in some organic solvents; the composition of fulvic acids includes carbon, hydrogen, oxygen and nitrogen, I also want to note that these acids contribute to the active destruction of the mineral part of the soil.
The value of humus for plants
All the merits of humic substances are still not known, therefore, the following are only the main ones that are firmly rooted in theory and practice.
Thus, humus is a fertilizer that contributes to:
- stimulation of plant respiration even with acute oxygen deficiency;
- improving the quality of agricultural products;
- enhancing photosynthesis, stimulating the activity of enzymes that are directly related to photosynthetic reactions;
- accelerate the transport and circulation of nutrients directly inside plants;
- plant growth and development;
- activation of root formation and development of the kidneys;
- increase resistance to external adverse effects;
- the formation of strong compounds with metals, the absorption of phosphates, nitrates and many others;
- increase in acidity on the root surface;
- increasing plant resistance to pesticides and herbicides, reducing their accumulation in the final product.
The use of humic substances in medicine
According to the results of various pharmacological tests carried out in order to identify what humus is, preparations that are based on humic substances can be used in our time as medicine and veterinary medicine as a nonspecific medicine that helps increase the body's resistance to various harmful factors.
Medical products based on the data of humic substances in our time already exist on the market. They are actively used in the treatment of radiculitis of various forms, diseases of the ears and nose, pharyngitis, rhinitis, arthritis, polyarthritis, arthrosis and many other diseases. The advantage of these drugs is that they are non-toxic.
Mysteries of Humic Substance
So the story came to its logical conclusion about what soil humus is, about its formation, properties and functions. The only thing I want to add is a few words about the riddles of humic substances. As you know, they are not characterized by a constant chemical composition, they do not have a certain molecular weight and a constant single color. Humic substances are still being studied by chemists, soil scientists, hydrobiologists, physicians, and pharmacists in order to explain all the puzzles stored in them, which, according to forecasts, will be solved a lot more.