The Effect of Humic Fertilizers on Some Physiological Processes and Yields of Corn in the Conditions of Northeastern Ukraine
Academician D. N. Pryanishnikov pointed out that manure will always remain one of the main fertilizers, despite the increase in the production of mineral fertilizers. However, in modern agrarian farms in Ukraine, the shortage of manure is compensated by other valuable fertilizers, such as leonardite, microfertilizers, and growth stimulants.
Leonardite acts as a source of organic matter, improving the physical and physicochemical properties of soils, as well as stimulating the physiological processes of plants due to the presence of soluble forms of humic substances.
The aim of our research was to study the effect of leonardite and liquid humic fertilizers (potassium humate) on corn in the conditions of sod-podzolic soils in northeastern Ukraine.
Research Methodology
Field experiments were conducted on sod-podzolic loamy soil. Fertilizers were prepared manually from leonardite with a concentration of humic and fulvic acids of 65%. Mineral fertilizers (ammonium nitrate, superphosphate, potassium chloride), leonardite, and potassium humate were applied in the spring during plowing.
Corn plants were treated with a 0.02% aqueous solution of potassium humate twice during the growing season:
- In the tasseling phase.
- In the phase of the beginning of cob formation.
Control plants were sprayed with water. The harvest was collected on September 12 in the milk-wax ripeness phase.
Research Results
1. Effect on Corn Growth
Plants treated with potassium humate and leonardite sprouted 2–3 days earlier than the control ones. Tasseling occurred 9–10 days earlier, and the interval between the appearance of male and female inflorescences was reduced by 4–5 days, which improved pollination.
| Experiment Variants | Plant Height, cm (milk-wax ripeness) |
|---|---|
| Control (without fertilizers) | 105.6 |
| N₆₀P₆₀K₆₀ (background) | 114.5 |
| Background + leonardite, 10 t/ha | 118.3 |
| Leonardite 10 t/ha + potassium humate 2 l/ha | 133.6 |
2. Biochemical Indicators
Humic fertilizers increased the content of vitamin C and catalase activity in corn leaves, indicating an enhancement of redox processes.
| Experiment Variants | Vitamin C, mg% | Catalase Activity, ml O₂ per 1 g in 3 min |
|---|---|---|
| Control (without fertilizers) | 54.56 | 13.3 |
| N₆₀P₆₀K₆₀ (background) | 62.24 | 17.3 |
| Background + leonardite, 10 t/ha | 75.68 | 22.8 |
| Leonardite 10 t/ha + potassium humate 2 l/ha | 77.44 | 27.2 |
3. Yield
The application of potassium humate and leonardite significantly increased the yield of green corn mass.
| Experiment Variants | Yield, c/ha | Yield Increase, % |
|---|---|---|
| Control (without fertilizers) | 309.7 | - |
| N₆₀P₆₀K₆₀ (background) | 369.5 | 19.3 |
| Background + leonardite, 10 t/ha | 420.0 | 35.6 |
| Leonardite 10 t/ha + potassium humate 2 l/ha | 456.4 | 47.4 |
4. Quality of Yield
Humic fertilizers improved the chemical composition of the green mass, increasing the content of crude protein, sugars, and the output of feed units.
| Experiment Variants | Crude Protein, % | Total Sugars, % | Feed Units, kg/ha |
|---|---|---|---|
| Control (without fertilizers) | 9.72 | 7.08 | 6194 |
| N₆₀P₆₀K₆₀ (background) | 10.26 | 8.67 | 7390 |
| Background + leonardite, 10 t/ha | 10.92 | 8.82 | 8400 |
| Leonardite 10 t/ha + potassium humate 2 l/ha | 11.40 | 9.21 | 9128 |
Conclusions
- Humic fertilizers activate physiological processes, increasing the content of vitamin C and catalase activity in corn leaves.
- Leonardite and potassium humate stimulate the growth and development of corn, increasing yield by 35–47% in the conditions of sod-podzolic soils.
- Organic fertilizers improve the quality of the yield, increasing the output of feed units, protein, and soluble carbohydrates.