What are Humic Acids?
1. Humic matter
Humic matter is formed through the chemical and biological humification of plant and animal matter
(pic.1.1) and through the biological activities of microorganisms.
Picture 1.1 — Typical vegetation of the Tertiary period.
The best source of humic acids are the sedimentation layers of soft brown coal, which are referred to as Leonardite. (pic.1.2, pic.1.3) Humic acids are found in high concentration here.
The biological center, the main fraction of natural humic matter, are the humic acids, which contain humic acid and fulvic acid. (fig.1.1, pic. 1.4, 1.5,) Humic acids are an excellent natural and organic way to provide plants and soil with a concentrated dose of essential nutrients, vitamins and trace elements. They are complex molecules that exist naturally in soils, peats, oceans and fresh waters.
Figure 1.1 — Humic Acid Fragment.
Picture 1.4 — Humic Acid (organic) at 35,000x magnification.
Picture 1.5 — Humic / Fulvic Acid.
Leonardite is organic matter that has not reached the state of coal. It differs from soft brown coal by its high oxidation degree as well as its high content of humic acids carboxyl groups. Fig. 1.2 shows the chemical extraction of leonardite.
Figure 1.2 — Isolation of humic acid and fulvic acid by Achard (1786).
Fig. 1.3 shows the formation of coal (lignite) to Leonardite and its basic extraction to obtain water-soluble humic acids (Rausa et al.).
Figure 1.3 — Coal oxidation according to Rausa et al.
According to contemporary of view, Humus does not consist of long-chained humic substances (fig 1.4 A), but of short-chained chemical substances of different kind (fig 1.4 B), which build aggregates with cations (yellow) and clay particles: polysaccharides (blue), polypeptides (green), aliphatic groups (e.g. fats) (bordeaux), aromatic lignin fragments (brown) (source: Simpson et al., 2002).
Figure 1.4 — Long chained (A) and short chained (B) humic substances.
Compared to other organic products, Leonardite is very rich in humic acids. While Leonardite is the end product of a humification process lasting 70 million years, the formation period of peat, for instance, is completed within only a few thousand years.
Therefore, Leonardite and other sources of humic acids differ in their molecular structure, which elucidates the extremely bioactive properties of Leonardite. This biological activity is about five times stronger than other humic matter. One kilogram of Leonardite corresponds to about five kilogram of other organic sources of humic acids.
Figure 1.5 — Coal formation: from bog via Lignite to coal.
In terms of humic acid content, one liter of LIQHUMUS® (liquid concentrate, pic.1.6, 1.7) is equivalent to 7–8 metric tons of organic manure.
Similarly, one kilogram of POWHUMUS® (concentrated powder, pic. 1.8, 1.9) is equivalent to about 30 metric tons of manure. However, Leonardite is not a fertilizer.
Leonardite acts as a conditioner for the soil and as a biocatalyst and biostimulant for the plant (pic. 1.10). Compared to other organic products, Leonardite enhances particularly plant growth (biomass production) and fertility of the soil.
Another advantage of Leonardite is its long-term effectiveness, as it is consumed as quickly as animal manure, compost or peat. As Leonardite is a degradation product, it does not compete with plants for nutrients such as nitrogen. This is not the case with incompletely decomposed compost, whereby the organic substances in soil are rapidly consumed up by micro organisms and mineralize without any humus formation.
Our Leonardite-based products improve the soil structure for up to five years.
Picture 1.10 — Development of root system of Tomato plant with Liqhumus (right) and with water only (left).
2. BENEFITS OF HUMIC ACIDS
Current scientific studies show that the fertility of soil is determined to a very large extent by the content of humic acids. Their high cation-exchange capacity (CEC), the oxygen content as well as the above average water holding capacity are the reasons for the high value of using humic acids for improving soil fertility and plant growth.
The most important feature of humic acids is their ability to bind insoluble metal ions, oxides and hydroxides, and to release them slowly and continually to plants when required. Due to these properties, humic acids are known to produce three types of effects: physical, chemical and biological.
2.1. Physical Benefits:
Humic acids physically modify the structure of the soil. They
2.2. Chemical Benefits:
Humic acids chemically change the fxation properties of the soil. They
2.3. Biological Benefits:
Humic acids biologically stimulate the plant and the activities of microorganisms. They
Optimal Utilization of Nutrients
Figure 2.1 — Increased nutrient deposit
by humic acid.
Figure 2.2 — Ca-Bridge between clay and humus.
Figure 2.3 — Growth is controlled by the scarcest resource.
Effect in soils
Compacted Clay Soils
Humic acids aerate compacted soils and improve their structure. Thus water, nutrients and roots can penetrate the soil more easily (s. fig. 2.4, 2.5, pic 2.3).
Light Sandy Soils
In sandy soils, poor in humus, humic acid coats the sand particles, improves the cation exchange capacity (CEC) and increases the ability of the soil to retain nutrients and water. Therefore, nutrients (particulary nitrate) remain available for the plants (s. fig. 2.6, 2.7, pic. 2.1, 2.2, 2.3).
Figure 2.6 — Sandy soils poor in humus can’t
Figure 2.7 — Effect of the cation exchange
capacity to sandy soils.
Picture 2.1 — Sandy soils without humic substance.
Picture 2.2 — Greening with PERLHUMUS®.
Picture 2.3 — Compacted clay soil without humic substance.
Salts are split up by the high cation exchange capacity (CEC) of Humic acids. Cations (e.g. Ca and Mg) are bound and chelated. The high osmotic pressure within the root area is reduced (s. fig. 2.8, 2.9, 2.10, pic. 2.4).
Figure 2.8 — Splitting of salt.
Figure 2.9 — Humic acids reduce the effects of salinity.
Figure 2.10 — Salinized groundwater in a soil.
Picture 2.4 — Highly Salinized soil.
Due to their high buffer capacity humic acids neutralize acidic soils, which decimate acid caused stress in plant roots. Elements harmful for plants, especially aluminium and heavy metals, are bound firmly and immobilized by humic acids. Hence, their toxicity is reduced and phosphate bound by aluminium is released (s. fig. 2.11, 2.12).
Figure 2.11 — Comp. scheme of light sandy, heavy clayey and rich in humus soils
Alkaline Soil As a result of the high pH value, many essential nutrients and trace elements are not in plant available form. Humic acids buffer the high pH and convert nutrients and trace elements into
plant receptible form by complexation. Phosphate bound by calcium is resolubilized and made available (s. fig. 2.11, 2.12).
Figure 2.12 — Humic acid opimizes the soil for the root development, e.g.nutrient uptake, soil aeration,
water-holding caoacity, cation exchange capacity (CEC) and the formation of clay-humus-complexes.
The addition of humic acids accumulates the organic matter in the topsoil. The erosion is effectively reduced by intensified root formation and stabilizing clay-humus complexes.
Humic acids increase the ability of the soil to retain water. Thus, water is available for the plants in dry periods too. That way drought caused stress situations to the plants are avoided and the wastage of precious water is reduced.
Pesticide, Herbicide, and Fungicide Charged Soils
Humic acids raise the efficiency of pesticides, fungicides as well as herbicides and immobilize their harmful residues.
3. ECOLOGICAL BENEFITS OF HUMIC ACIDS
The ecological benefits of humic acids are diverse, present profitable and effective solutions for environmental problems along with the preservation of the environment.
First of all, soils with a high content of humic acids are a guarantee for low nitrate leaching and for optimum nutrient efficiency. A well developed root system, which is achieved by a high content of humic acids, prevents that nitrate and pesticides mix in with ground water (s.fig 3.1). Futhermore, a low content of nitrate is an indicator and a prerequisite for appropriate organic agriculture.
It happens very often that growers use fertilizers more than plants can take up. This leads to nitrate concentration in soil, which is later to be found in ground water. As a result, this contaminated water can only be purified by a complex and expensive wastewater treatment process.
Important: Instead of curing the symptoms (water contamination) only, the basic causes (nitrate leaching) need to be tackled.
Secondly, humic acids reduce the over salination problem in the application of watersoluble mineral fertilizers. Humic acids are able to decrease high salt con-tents in soils and thus the resulting toxicities. Especially the NH4-toxicity of fertilizers containing ammonia is reduced, which is of great importance for young plants particularly.
Generally, humic acids reduce root burning which comes about through excessive salt concentrations in soils after fertilization; in case of permanent high levels of salt in soils, these are reduced. Furthermore, when humic acids are mixed with liquid fertilizers, the undesirable smell is diminished.
Thirdly, humic acids are an effective means to fight against soil erosion. This is achieved by increasing the ability of soil colloids to combine and by enhancing root system and plant development.
Leonardite and humate -based products are certificated for organic agriculture by renown organizations and institutions of agriculture worldwide (s. fig 3.1).
Figure 3.1 — Reduction of nitrate leaching
4. ECONOMIC BENEFITS OF HUMIC ACIDS
Humic acids chelate nutrient compounds, especially iron, to obtain a suitable formfor plant utilization in soli, so the nutrient supply of plants is optimized. High increases up to 70% in yield, accompanied by a reduction up to 30% in the use of fertilizers and pesticides, as well as better and healthier growth of green grass, ornamentals, agricultural crops and woods can be attained with the regular application of first-quality humic acids. Furthermore, water holding capacity of soils is increased considerably, which means that the use of water can be reduced substantially. Best economic results can be obtained in light and sandy soils poor in humus as well as on recultivation fields.
The diverse positive impacts of humic acids are to be observed particularly in such soils. This is true for almost all soils in dry and warm regions. As a result of the high mineralization rate of organic substances, providing these soils with stable humic acids is indispensable for the maintenance and improvement of soil fertility.
HUMINTECH® offers a variety of products which successfully fulfil the needs of different soil conditions and plants (s. fig. 5.1). As a result, soils treated with HUMINTECH® products secure qualitative and quantitative increases in yield and reduce material and labor costs. Made of humic substances of the highest quality, HUMINTECH® extensive product line has been designed to suit the demands of a healthy community.
Figure 5.1 — Some products of the HUMINTECH® product line