What are Humus substances?

The University of Latvia Faculty of Geography and Earth Sciences

The active substance of the preparation are humus substances – a mixture of physiologically active substances containing amino acids, hydrocarbons, nutritional substances of plants (nitrogen, potassium, phosphorus) and microelements (iron, copper, zinc, manganese, boron, molybdenum, etc.)

The use of humus substances facilitates germination of seeds, ingrowth of plants and growing of roots, as well as increases productivity and facilitates resistance of plants against different fungous diseases and unfavourable climatic factors (drought, frost, etc.)

The product is manufactured from natural and ecologically clean raw material – peat in the content of which there is a great number of different groups of biologically active substances – amino acids, hydrocarbons, ferments, A and B vitamins.

Humus substances are characterized by high diversity of properties, however their most significant properties which are important in the processes taking place in the environment are as follows:

  1. Resistance against the microbial influence – HV are very resistant against the microbial degradation. Therefore the age of HV may reach even 15 000 and more years.
  2. The ability to connect with the mineral components and organic connections of the soil and water. This HV property is very important in the studies on the soil and water pollution and its migration.
  3. The ability to connect with the metal iones – humus substances have high content of such functional groups which are able to make complex connections with metal iones. Therefore, HV is able to influence transportation of metals and their destiny in environment.

The ability of HV to make stable complexes with the soil or water non-organic and organic components has a significant role in establishment and migration of the environmental polllution level, as well as in the transformation process of the polluting substances.


The following main environmental functions of humus substances should be specified:

  1. Accumulative function – all the main feeding elements of alive organisms: 90-99% N, considerable part of P and S, as well as K, Ca, C, Mn, Fe and almost all microelements which accumulate are mainly related to HV;
  2. Transportation function – humus substances determine establishment of the geochemical flows of mineral and organic substances, especially in the water environment by making stable but relatively easily soluble HV connections with metal iones, hydroxides, some organic substances and alumosilicates;
  3. Regulating function – determines a lot of processes taking place in the environment:
    - Establishment of soil, peat structure and physical properties;
    - Maintenance of the reaction balance in the ion exchange reactions, echcange of acids-bases;
    - Feeding of the mineral components of the alive organisms (regulates solution of the mineral components in water and accessibilitgy to the alive organisms);
    - The heat regime in the environment and intensity of photosynthesis (influences the capabilities of spectral reflection, thermal capacity and thermal conductivity of the soil mass);
    - Differentiation process of the chemical content of the environment.
  4. Protection function – HV acts as a “geochemical barrier”:
    - protects the soil from drought and extensive humidity;
    - protects the soil from erosion and deflation;
    - maintains the physical properties of the soil under anthropogennic loads;
    - decreases the negative influence of toxic substances and prevents their migration within the environment, etc.
  5. Physiological function – manifests itself mainly as direct physiological influence of humus substances to plants and microorganisms.

Since the content of elements of humus substances is investigated much enough by using the obtained informtion it is possible to relatively precisely characterize the content of elements of HV. The content of elements of humin acids (HA) and fulvic acids (FA) is made of C, H, O, N, S and P (excluding the content of ash) of 98-100%. Besides, humin acids contain 50-60 % C, 30-35 % O, 4-6 % H, 2-4 % N, while fulvic acids are characteristic of the lower content of C (40-50 %) and higher content of O (~40 %) in comparison with humin acids (1. tab.). ).

Table 1.
The content of elements of humin acids and fulvic acids

Humus substances

C %

H %

N %

S %

O %


Humin acids







Fulvic acids







The second significant characteristic of HV structure and properties is the content of functional groups. The main functional groups are shown in Table 3.
Table 2.
Average value of the functional groups of humin acids and fulvic acids (meq g-1

Functional groups

Humin acids

Fulvic acids

Total acidity






Phnol OH



Spirits OH



Carbonyl group (C = O)



Metoxi group (OCH3)



The main properties determining the use of HV and practical possibilities of their use
The role of humus substances in soil establishment and their use in agriculture

The humus substances development sources of which in the soil is mainly transformation of the organic remains of various species and animals as a result of the reactions of the influence of microorganisms and condensation reactions is one of the most important components. In addition to various physiological and physical effects they improve the soil structure, optimize air, water and temparature regimes, as well as increase and establish the reserves of food elements by connecting different substances and connections of organic and non-organic origin. For example, within the soil treatment process its intensive aeration takes place by ensuring oxidation of different connections and facilitating the development of plants and microorganisms which increases development intensity of new HV. At the same time, the HV located in the soil also actively attracts oxygen by increasing the amount of the chemically connected oxygen in the soil.

HV also performs important protecting functions by connecting toxic heavy metals, various pesticides and such nutritional substances which are able to create difficultly soluble compounds. For example, compounds of phosphorus – HV protect phosphates from development of insoluble compounds but plants simply release them by creating complexes for humus substances with various organic substances which are discharged by their root systems.

An important role of submolecular humus substances is their easy accessibility to microorganisms, as well as participation in the mobilization of mineral components of the soil by releasing a lot of elements from different difficultly soluble compounds. At the same time, they also play a conservative role by providing permanently stable properties for the soils – the level of the humus content, cation exchange capacity, buffering capacity, etc.

By taking into account the importance of HV regarding soil, an issue on their use in agriculture for improvement of the soil quality and properties is actual, the benefit is considerable – resistance of biogenic elements against leaching increases, they are released gradually in parallel with the positive physiological factor the physical and chemical properties of the soil also improve.