Properties and efficiency factors of the Lower Dnieper leonardite deposits as a basis for modern humic preparations Agro.Bio
The lower reaches of the Dnipro River, particularly in the Kherson region, are home to large reserves of high-quality organic matter. In the past, these deposits, amounting to tens of millions of cubic meters, were rarely used as fertilizer due to the enormous logistical and economic costs involved: applying raw organic matter required enormous doses. Today, thanks to modern deep extraction technologies, Agro.Bio harnesses this rich natural resource, which is based on leonardite (a natural mineraloid, oxidized lignite or brown coal, which serves as a powerful organic fertilizer and the main source of humic and fulvic acids), to create highly concentrated liquid humic fertilizers. They are cost-effective, easy to use, and highly effective.
We set out to study the key factors in the effectiveness of leonardite and demonstrate rational ways of using it in southern Ukraine, which are currently implemented in products such as Agro.Bio Potassium Humate and Agro.Bio Totem .
1. AGROCHEMICAL CHARACTERISTICS AND ASSESSMENT OF SUITABILITY OF LEONARDITE
Agrochemical studies of the Kardashinskoye, Solontsovskoye, Poyma I, and Kazachyelagerskoye deposits have shown that the local leonardite is unusually rich in humic compounds and has a high degree of oxidation and humification (especially in the Kardashinskoye and Solontsovskoye deposits—up to 55–65%). The acidity is slightly acidic, close to neutral, which is optimal for creating high-quality humic extracts.
Table 1. Agrochemical characteristics of leonardite
| Field | pH (aqueous) | pH (salt) | Ash, % | Organics, % | Humus, % | Oxidation degree, % | Moisture capacity, % |
|---|---|---|---|---|---|---|---|
| Kardashinsky | 6.56 | 6.23 | 19.32 | 80.68 | 52.50 | 55–60 | 640 |
| Solontsovskoye | 6.38 | 6.16 | 19.32 | 80.68 | 64.90 | 60–65 | 635 |
| Floodplain I | 6.24 | 6.10 | 40.97 | 59.03 | 38.65 | 45–50 | 760 |
| Cossack camp | 6.75 | 6.50 | 43.37 | 56.62 | 46.50 | 45–50 | 754 |
Calcium, interacting with humic acids, has a significant impact on the properties of organic matter. The high calcium content of Kardashinsky and Solontsovsky leonardites results in their exceptional biological activity, making them ideal raw materials for Agro.Bio biotechnology.
Table 2. Composition of leonardite ash from the main deposits (% of dry matter)
| Field | SiO₂ | CaO | Sum of sesquioxides and phosphorus | Including P₂O₅ |
|---|---|---|---|---|
| Kardashinsky | 64.42 | 15.78 | 9.40 | 1.05 |
| Solontsovskoye | 54.99 | 15.84 | 9.10 | 1.34 |
| Floodplain I | 79.28 | 2.96 | 10.82 | 0.47 |
| Cossack camp | 75.86 | 4:30 | 15:30 | 0.46 |
In addition, the raw material contains 2–3% total nitrogen, microelements (manganese, copper, molybdenum, boron, cobalt), which in chelated form pass into modern liquid preparations.
2. FORMS AND COMPOSITION OF ORGANIC MATTER
Leonardite's properties depend on its active functional groups (phenolic hydroxyls, carboxyl groups). Modern extractants allow for the complete extraction of these groups, converting them into a water-soluble, plant-bioavailable form.
Table 4. Elemental composition and number of functional groups (mg-eq per 100 g)
| Faction (Kardashinsky) | N | C | H | O | C:H | COOH | OH | Sum of acidic groups |
|---|---|---|---|---|---|---|---|---|
| Leonardite original | 3.61 | 48.36 | 5.81 | 41.22 | 8.33 | 19.1 | 199.0 | 218.1 |
| Humic acids | 4.47 | 61.50 | 5.01 | 28.02 | 12.28 | 327.1 | 620.9 | 954.0 |
| Fulvic acids | 4.44 | 41.09 | 5.82 | 47.65 | 7.06 | 111.6 | 358.1 | 469.7 |
| Water extract | 3.46 | 37.13 | 5.43 | 52.98 | 6.83 | 58.1 | 338.4 | 396.5 |
Humic acids contain the largest number of active functional groups (up to 954 mg-eq/100 g). This enormous exchange capacity allows Agro.Bio products to effectively retain nutrients in the soil and continuously supply them to the roots.
The initial biological assessment (based on the root length of wheat and cucumber seedlings) showed that purified humic acids from leonardite provided maximum physiological stimulation – the increase in root length was up to 138% compared to the control (water).
3. LEONARDITE AS A SOURCE OF NUTRITION FOR PLANT ...
Historically, raw leonardite has been used as a direct nitrogen-phosphorus fertilizer. Our long-term vegetation experiments with barley have shown:
- Leonardite nitrogen is absorbed by plants very slowly in its raw form. Replacing mineral nitrogen would require unrealistic doses (up to 300–600 tons/ha).
- Phosphorus and potassium from leonardite are better absorbed, but still require huge application rates.
Key conclusion: Viewing raw leonardite simply as a source of NPK is irrational and economically unviable. In the complex complex of factors, the key role belongs not to the macronutrients, but to the humic substances in leonardite as powerful physiological stimulants.
4. ORGANIC MATTER AS THE MAIN FACTOR OF EFFICIENCY
Leonardite's humic and fulvic acids act as biocatalysts. They enhance cellular enzymatic activity, activate metabolism, stimulate cell division, and promote vigorous root growth.
In pot trials with tomatoes, the dry matter weight of pure humic extract was 1,000 times less than the weight of crude leonardite applied, yet this milligram extract had a similar (or greater) effect on yield! This phenomenon underlies the use of concentrated Agro.Bio products (with a working rate of only 2 l/ha).
Table 13. The effect of leonardite organic matter on tomato yield (sandy crops)
| Experimental option | Fruit yield (g/vessel) | % to control | Nitrogen removal (% of control) | Phosphorus removal (% of control) |
|---|---|---|---|---|
| Control (NPK) | 277 | 100.0 | 100.0 | 100.0 |
| NPK + water extract | 330 | 133.0 | 106.5 | 116.0 |
| NPK + humic acids | 393 | 141.9 | 112.5 | 134.8 |
| NPK + raw leonardite (100 g/vessel) | 421 | 152.0 | 124.5 | 126.2 |
Under the influence of humic substances, the general condition of plants improved, fruit ripening accelerated, dry matter and vitamin C content increased, and the transpiration coefficient decreased (plants used moisture more economically, which is critical for the south of Ukraine).
Experiments using labeled radioactive phosphorus (P³²) have proven that leonardite humic acids dramatically accelerate the uptake of phosphorus into plant tissues within the first hours after application.
CONCLUSIONS
- Leonardite deposits of the Lower Dnieper fields (especially the Kardashinsky and Solontsovsky) have a high degree of oxidation and are a valuable raw material for the production of modern humic fertilizers.
- The use of raw leonardite as a direct source of NPK is impractical, as it requires the application of gigantic and economically unprofitable doses.
- A significant and key factor in leonardite's effectiveness is its organic matter (humic and fulvic acids). These promote maximum absorption of mineral fertilizers, optimize water and carbohydrate metabolism, and promote vigorous root development.
- The humic acids isolated from leonardite have the highest physiological activity and are extremely rich in carboxyl and phenol hydroxyl functional groups.
Agro.Bio Expert Comment: Building on this strong scientific foundation, Agro.Bio produces highly purified, concentrated organomineral complexes. Applying Agro.Bio's Potassium Humate and Agro.Bio's Totem at rates of just 2 l/ha allows for the full biostimulating potential of the relict organic matter of leonardite to be unlocked. This guarantees farmers maximum absorption of applied mineral fertilizers, reliable drought protection, and stable yield growth without the need to transport and apply thousands of tons of raw materials.