Organo-mineral fertilizers and chemical characteristics of humic acids

Types of organo-mineral fertilizers:

• Nitrogen-rich rgano-mineral fertilizers.
• Humic fertilizers are fertilizers that regulate the absorption of hard-to-reach calcium and iron phosphates; structure-forming fertilizers, which determine the formation of soil structure; favorably influencing the water and thermal regime of soils; containing very small amounts of organic substances that can be absorbed directly by higher plants and affect their development.
• Fertilizers that cause partial sterilization of soils, fertilizers that promote the absorption of nitrogenous substances by plants from the soils themselves, and, finally, fertilizers that stimulate the growth and development of plants.

A special section of organo-mineral fertilizers is humic fertilizers. The role of humic substances in soil fertility is very large and diverse.

Various authors give different explanations for the favorable effect of humic acids on plant growth, believing that they are either regulators of the flow of mineral substances through plant membranes, or carriers of concomitant substances with hormonal action.

Some believe that humic acids themselves are growth promoters. Humic acid, being in a dissolved state, is able to penetrate through plant membranes and thus be absorbed by plants. To understand the physiological role of humic acids, first of all, it is necessary to know the properties of their chemical nature and structure.

Humic acids differ sharply from other organic compounds in their chemical and physicochemical properties. They are formed everywhere in nature as a result of the changes that, under the influence of microorganisms, as well as as a result of various chemical reactions, the remains of plants and animals undergo in soils, peat bogs, lake sediments and brown coal seams. The process of humification is a peculiar example of a process in which the inhibitory effect of time against the final destruction of organic substances is manifested. The chemical processes during humification proceed in such a way that over time, more and more stable compounds are formed that can withstand further changes and mineralization.

To understand the process of humification, it is necessary to know what substances are the starting materials for the formation of humic acids.

Some authors considered carbohydrates to be the parent substance of humic acids. However, their works do not provide experimental data confirming the indicated view on the origin of the studied acids.

AGROBIO scientists have experimentally shown that the process of formation of humic acids is associated with the biochemical activity of bacteria and lower fungi, and carbohydrates do not take a direct part in it. Thus, lignin and lignin precursors can mainly be considered as a source of humic acids. “The humification of “lignin” is reduced to the oxidation of those of its constituent parts that contain quinone and polyphenol groups; in this case, various condensed products with the character of oxyquinones are obtained. Investigating the question of agents causing humification, our biologists confirmed the importance of fungi for this process and pointed out that humic acid can also be formed during the decomposition of fungal mycelium.