The concept of “humates” is now firmly connected with different areas in our life - in agriculture, medicine and industry. Humates are preparations derived from humic substances (HS) that are widely found in nature. HBs are found in sea and river water, in bottom sediments, soil, peat and brown coal.
The content of HS in soils is at the level of 1-15%, in peat - 25-30%, in brown coal - up to 85%. The very concept of “humic substances”, “humates” is associated with the soil and came from the word “humus” - a complex of dark-colored organic compounds that determines the potential soil fertility. So, for example, the content of HS in chernozems (the most fertile soils) reaches 12%.
Most naturally occurring HSs are in a water-insoluble form that does not have significant economic value. For the practical use of HS, they must be converted into a water-soluble form - humates.
On an industrial scale, humates are obtained from peat, sapropel and special types of brown coal - Leonardites. The properties of humates obtained from different sources are largely similar to each other, but differ significantly in some parameters. These differences largely determine the nature and results of the use of humates.
The main importance of humates is associated with their high biological activity, which determined the widespread use of these drugs in crop production, animal husbandry, medicine, and environmental management. However, despite the many years of successful practical use of humates, a scientific justification of the biological activity of these compounds has not yet been obtained. The main obstacle to creating a theory of the action of humates on living objects is the complexity of the structure of humic substances themselves and the multicomponent nature of the preparations extracted from natural raw materials. This problem is compounded by the fact that the composition of humic preparations is unstable and depends on the source of raw materials and the technology used to isolate them.
At the same time, despite the noted problems, the demand for humates and the range of humic preparations on offer are constantly expanding. The consumer has a question: which humates are better, how to understand this variety of offers? It is clear that there are several well-established humate producers on the market. But they produce humates from various sources - from brown coal, from sapropel, from peat, from lignin. Each of the manufacturers, of course, advertises its goods in the best quality.
Let's try to figure it out, without delving too much into the chemical, physico-chemical and biochemical subtleties. We only note that the improvement in the functioning of living organisms under the influence of humic preparations is noted at low concentrations of their aqueous solutions - from 0.005 to 0.05%; higher concentrations cause gradual depression and death.
The complex composition of any humic preparation can be conditionally divided by the molecular weight of the components into 4 large groups , whose individual importance in biological and economic terms is different, and the result of their application depends on the quantitative ratio between them and a complex, sometimes multidirectional, the nature of their influence on the objects of influence.
1st group - inorganic water-soluble compounds and insoluble mineral impurities. Substances included in the first group of compounds have practically no significant value, since they are practically ballast. However, this group may include some biologically significant trace elements intentionally introduced into the drug, for example, such as Humate + 7.
2nd group - water-soluble low molecular weight (up to 5 kD) organic compounds, among which are determined organic acids, amino acids, sugars, alcohols, phenols and other organic compounds that are formed during the decomposition of more complex biostructures. Among the second group of compounds, both stimulants and inhibitors of physiological and biochemical processes can be found. These low molecular weight organic compounds can also serve as a source of nutrition for plants and microorganisms, but with the current low concentration of humic preparations, their value is small.
3rd group - water-soluble organic compounds with an average molecular weight (up to 50 kD), among which fulvates prevail - fulvic acid salts. Fulvic acid, and most fulvates, have high chemical and biological activity. Received from peat where ballast substances are present (more than 60%).
Fulvic acid easily forms mobile complexes and salts with a variety of molecules and atoms, including heavy metal atoms. These complexes can penetrate into living cells and tissues of organisms and have a certain effect there. This action can be either positive or negative, depending on the transport of which substances is facilitated in the form of such complexes. Some researchers believe that fulvic acids and fulvates, in general, have higher biological activity than humic acid and its salts (humates). However, the practical use of preparations enriched in fulvates is economically disadvantageous due to the high cost of the process of their isolation and purification from impurities.
4th group - water-soluble high molecular weight (> 50 kJ) organic compounds, among which salts of humic acids (humates) predominate. Like fulvic acid, humic acid forms various complex compounds, but it itself, like most of its salts and complexes, is practically insoluble in water (with the exception of humates of alkali metals and ammonium). This humic acid is very different from fulvic acid.
Researchers believe that the biological activity of humic acid and its complexes is determined by the surface-active properties of their molecules, which stabilize the surface of living cells. Humates do not penetrate inside the cells. As a result of the formation of sedentary complexes, humates are retained in the integumentary tissues of plants, exerting a longer and softer effect on them. In the soil, water-soluble humates quickly turn into inactive complexes, due to which the soil structure improves and harmful substances (heavy metals, pesticides, etc.) are removed from the geochemical and biological circulation.
In the series of humic preparations isolated from lignin, sapropel, peat, and brown coal, the proportion of components with a high molecular weight, first of sulfates, and then of humates, that is, the amount of humic substances proper, increases accordingly. In brown coals - leonardites, the content of humic acid and, therefore, in the preparations extracted from them, the content of humates reaches 85-90%. In this series, the certainty and predictability of the result from the use of humic preparations also increases, since the variability of the chemical properties of the compounds in the groups mentioned above decreases.
It should also be noted that the most favorable combination of biological activity (increasing productivity in plant growing and animal husbandry), agrogeochemical properties (detoxification and improving the fertile properties of the soil) and environmental friendliness of production are most related to humic preparations made from brown coal deposits located in Irkutsk region. The profitability of using these drugs is much higher than drugs produced from raw materials that initially contain a high proportion of ballast substances (peat, lignin, sapropel).
Ph.D. Shvetsov S.G. (SIPHIBIR SO AN)