Humus is the main organic matter of the soil, containing nutrients necessary for higher plants. Humus makes up 85-90% of soil organic matter and is an important criterion for assessing soil fertility.
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 that contains nutrients that plants need.
Humic substances belong to a special group of chemical compounds characteristic of the earth’s soil cover, that is, they are specific only for the soil. Surely what humus is, now it became clear, but 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 quite complex.
Dark color, which is absent in plants. The humus contains a very valuable humic acid containing a lot of carbon (about 60%), oxygen (about 35%), nitrogen (on average 5%), phosphorus, sulfur, iron, and so on. Based on the foregoing, another answer follows to the question of what humus is. Humus is a term that unites a huge complex of chemicals containing an organic part (humic and fulvic acids), an inorganic component (chemical elements of inorganic origin, or, in other words, minerals that are included in the number of humates and fulvates). The main data on the content of humus in the soil is given in the table:
|Natural area||Soil type||Humus content||Soil properties|
|Arctic deserts||arctic||2-3%||not used for growing crops|
|Tundra||in tundra-gley soils||2-3%||low-powered|
|Broadleaf forests||in gray forest soils||4-6%||fertile|
|Steppe||chernozems, chestnut||7-10%||the most fertile|
|Semi-empty||brown, gray-brown||1-2%||soil salinization|
You have already met the concept of humus, the next open question is what is soil humus, and how is it formed? Soil humus is nothing more than a waste product of various organisms, primarily earthworms. The humus formation process is long-term. Vegetation, metabolic products, animal remains – all this is food for the organisms that live in the soil. Some part of all this lends itself to mineralization, and the other to biochemical enzymatic decomposition and oxidation (humification), during which organic compounds are synthesized, and humus is formed.
Humus predominates in it, as well as humic acids, which are transformed over time, oxidizing as a result to carbon dioxide and water. It is very important that that the ways of humus transformation – mineralization or humification – depend directly on soil and climatic conditions. Insufficiently warm and humid climates, the oxidation process occurs very quickly, and almost all plant litter is mineralized, which prevents humus from accumulating in the soil.
In cold climates, the transformation of litter is slightly slowed down, and their number is small, as a result, the humus content in the soil is low. Moderate climates without waterlogging are optimal for humification. So, from all of the above, we can draw the appropriate conclusions: in order to get a good harvest, the plant simply needs carbon dioxide; carbon dioxide in the soil, as a rule, is formed as a result of the 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 and form humus-humus, which is the most important component of soil fertility.
Functions of humus
Creates a solid soil structure, due to which a favorable circulation of water, an air of the required temperature is ensured and good root growth in the soil is predetermined. Humus also helps to impart cohesion to light soils and to loosen dense soils.
It is an excellent store 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.
- Pestilence (humus of podzolic soil) is very coarse, a large amount of detritus, which forms at low biological activity in an acidic environment.
- Moder (humus of sod-podzolic soil), which is formed at medium biological activities under conditions of an acidic reaction of the environment and weakly interacts with the mineral part of the soil.
- Mull (humus of chernozems), which forms at very high biological activities in a neutral reaction of the environment, actively interacting with the mineral part of the soil.
- Anmoor (humus of sod-gley soil), which forms in temporarily moist soils. Oligotrophic peat, which is the “poor humus” of raised bogs.
eutrophic peat, which is rich in humus of lowland bogs.
The importance of humus in soil fertility Humus is actively involved in the process of soil formation.
He is assigned the most important role directly in the formation of the soil profile. Humus promotes the adhesion of soil particles into aggregates (lumps), creates valuable agronomic structures and physical properties of the soil favorable for plant life.
contains essential plant nutrients 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 content of humus in soils. Humus also helps to give the soil a dark color, thereby better absorbing the sun’s energy. 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.
In the composition of the humus of the soil, one can distinguish a specific part (about 90%), consisting of humic substances, and a nonspecific part (the rest), consisting of non-humified organic substances. The humic substances of soils, in turn, are represented by: humic acids – high-molecular nitrogen-containing organic compounds with a cyclic structure, insoluble in water and acids, but soluble in weak alkalis, the composition of humic acids includes carbons (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; alkali humates are readily soluble in water, thus forming colloidal solutions; the humates of calcium and magnesium are not soluble in water, they 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 can dissolve in some organic solvents; fulvic acids include carbon, hydrogen, oxygen, and nitrogen; I would also like to note that these acids contribute to the active destruction of the mineral part of the soil.
All the merits of humic substances are still not known, therefore, below are only the main ones that are firmly rooted in theory and practice. Thus, humus is a fertilizer that promotes: stimulation of plant respiration even with an acute oxygen deficiency; improving the quality of agricultural products; enhancing photosynthesis, stimulating the activity of enzymes that are directly related to photosynthetic reactions; accelerating the transport and circulation of nutrients directly inside plants; plant growth and development; activation of root formation and development of the kidneys; increasing resistance to external adverse influences; formation of strong compounds with metals, absorption of phosphates, nitrates and many others; an increase in acidity on the surface of the roots;
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 based on humic substances can be used in our time in medicine and veterinary medicine as a nonspecific drug that helps to increase the body’s resistance to the effects of various harmful factors …
Medicines based on these humic substances already exist on the market today. 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. Riddles of humic matter So the story about what soil humus is, about its formation, properties, and functions came to its logical conclusion.
The only thing I want to add is a few words about the riddles of humic substances.
They do not have 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, doctors, pharmacists in order to explain all the riddles stored in them, which, according to forecasts, will be solved a lot more.