When humic acids are used as plant growth regulators, it is not the humic acids themselves that have physiological activity, but their salts of the univalent alkaline metals (sodium and potassium) and ammonium. This is due to the fact that humic acids are insoluble in water, so they are not absorbed by plants, while salts of the monovalent alkaline metals and ammonium are well soluble in water and accessible to plants.

Humic acids have a versatile effect: they activate bioenergetic processes, stimulate metabolism and synthetic processes, improve penetration of nutrients through the plasmalemma, enhance enzyme systems, increase adaptive properties of the plant organism. Depending on environmental conditions, they may differ in persistence and activity, so they can be used as fertilizers and plant growth stimulators.

The reason of physiological activity of humic acids is their action on the bioenergetic system of plant organism (Khristeva L.A., 1973). Increase in energy reserves of the organism promotes protein synthesis, due to which plant resistance under extreme conditions and photosynthetic capacity increase.

The ability of humic acids to complexation and their sorption activity make it possible to use them for binding heavy metals to insoluble compounds on polluted soils.

Humic acids interact with metal cations in different ways: calcium ions form calcium salt-like humates, in which an ionic form of carboxyl groups is observed. Zinc ions replace hydrogen of carboxyl groups. Copper replaces the hydrogen of both carboxyl and phenolic groups. In all cases, the redeposition of humic acids in the form of insoluble or slightly soluble metal salts or complexes occurs.

Humates are involved in soil structure formation: on light soils aggregation takes place, on heavy soils they prevent formation of crusts and cracks, improve aeration, water-holding and water-transmitting capabilities.

The use of humates in agriculture contributes to:

• increase the yield of cereal, vegetable and forage crops;
• Increasing the germination and germination energy of seeds;
• strengthening of root formation and metabolism of plants, absorption of
• elements of mineral nutrition, increasing the resistance of plants to diseases, frost and drought.

Sodium, potassium and ammonium humates are used. Sodium and potassium humates are obtained by saturation with potassium or sodium hydroxides. Ammonium humate is obtained by treating raw material with ammonia solution.

For irrigation, a 5% solution of humate diluted at a ratio of 1:1000 is used, for seed treatment – 1:500, for treatment of tubers and seeds of cereal crops – 1:250. Spraying of plants during vegetation period is carried out 2-4 times.

Microelements, organic acids, biologically active substances, amino acids, vitamins can be added to solutions of humic acid salts which are used by germinating seeds, plants and microorganisms living in the soil. More than 60 preparations, grouped into a group of “Humic Acid Fertilizers” are produced.

The different chemical composition of the preparations expands the range of their application. They can be used for seedbed preparation and spraying of vegetative plants. Production tests of these preparations in various soil and climatic conditions have shown their positive impact on the yield of all crops. Vegetable, fruit and forage crops were the most responsive. It is reasonable to combine application of humic acid-based fertilizers with the pre-sowing preparation of seeds and spraying of crops with plant protection agents. Combined application with pesticides also has the advantage that they remove the stress effects of toxic chemicals on cultivated plants.