Dosages of Humate-Based Fertilizers, Application Methods, and Combinations with Other Fertilizer Types

Simultaneously with testing the agronomic effectiveness of humic fertilizers, research was conducted to determine optimal doses, application methods, and the most rational combinations with other fertilizers.

Corn Research

In corn experiments, the influence of various doses and forms of humic fertilizers on root nutrition conditions was studied. Agro.Bio preparations had a positive effect on corn root nutrition, although soil nutrition conditions varied depending on the fertilizer option. The greatest effect, confirmed by agrochemical analysis of soil nitrogen and phosphorus regimes, was observed with the application of a high dose of leonardite.

Nutrient Accumulation in Soil

Table 9. Nutrient Accumulation in Soil Under Corn on Differently Fertilized Areas of Gray Forest Soil

(plow horizons, mg per 100 g of absolutely dry soil)

Chemical analyses of soils under various crops showed a significant influence of dry forms of humic fertilizers on the nutrient regime of gray forest soils. Liquid organomineral fertilizers (Adept Agro.Bio) differed little from pure water in mobilizing nutrients but stimulated corn seed germination. The first sprouts appeared on plots with Adept Agro.Bio.

Effect on Corn Germination

Table 10. Effect of Humic Fertilizers on Corn Germination (% of total plants)

Liquid fertilizers (Adept Agro.Bio) stimulated seed germination, while dry forms of leonardite (especially at 2 t/ha) inhibited seedling development. However, later, plants on plots with leonardite caught up and surpassed in growth those fertilized with liquid forms, demonstrating powerful stems and large leaves.

Phenological Observations

Plants fertilized with liquid forms had worse phenological indicators in later development periods. The difference in development persisted until cob formation. The 2019 climate conditions were favorable for corn: hot weather from late May to June 10 (temperature 25–31°C), precipitation of 25–40 mm from June 9 to 15, and 302 mm from April to August (compared to 146 mm the previous year). The first frost occurred on October 12, allowing corn to grow intensively in August. Daily growth on fertilized plots was 8.2–13.1 cm.

Table 11. Corn Growth Observation Data (average of 50 measurements, stem height, cm)

Visual Observations

• Fig. 1. Effect of humates on corn development: 1 — unfertilized plants, 2 — plants fertilized with solid humic fertilizers (2 t/ha).
• Fig. 2. Effect of humates on corn development: 1 — no fertilizers, 2 — plants fertilized with leonardite (0.8 t/ha).
• Fig. 3. Effect of humates on corn development: 1 — no fertilizers, 2 — plants fertilized with Adept Agro.Bio.
• Fig. 4. Effect of humates on sugar beet development: 1 — unfertilized plants, 2 — plants fertilized with leonardite (2 t/ha).

Liquid humic fertilizers, water, and the control variant showed no significant differences in plant condition. Earlier sprouted plants with liquid fertilizers did not achieve full development due to nutrient deficiency.

Vegetation Experiments

In vegetation experiments, the leonardite dose of 2 t/ha was most effective. Plants had the tallest stems and best development. Lower doses of leonardite and combinations with Adept + NPK provided less growth, but leaf surfaces were well developed.

Oats Research

In vegetation experiments with oats (16 plants per vessel), the effectiveness of humic fertilizers in combination with potassium humate + NPK was studied. This combination showed advantages compared to using only carbon-humic fertilizers. Plants looked equally good, but grain with the combination had better commercial quality. With only superphosphate, plants developed worse than the control.

Biochemical Processes

Amino acid and monosaccharide determination showed the physiological activity of humic fertilizers. The ratio of simple carbohydrates, soluble substances in corn silage juice, and protein indicates enhanced assimilation of nitrogenous compounds and protein synthesis in fertilized plants.

Table 12. Effect of Humic Fertilizers on Corn Silage Quality (% of dry matter)

Metabolic processes were most intensive with Adept, although the combination with leonardite showed slightly lower biochemical activity.

Yield

Table 13. Effect of Humic Fertilizers on Corn, Beet, and Oats Yield on Gray Forest Soil (t/ha)

Leonardite and its combination with superphosphate had the greatest effect on corn, oats, and sugar beet yields.

Vegetation Experiments

Table 14. Effect of Humic Fertilizers on Yield in Vegetation Experiments (g per vessel)

Potato Yield

Table 15. Potato Yield on Gray Forest Soil Fertilized with Humates (t/ha)

Humic fertilizers were ineffective for potatoes on gray forest soils in Chernihiv region, but cabbage responsiveness to these fertilizers depended on the variety, requiring additional research.

Conclusions

1. Humic fertilizers based on leonardite, using oxidized coals from Chernihiv region, are an effective means to increase yields.
2. Leonardite improves soil nutrition conditions by activating nutrient mobilization in absorbable forms, promoting humus compound accumulation through the formation of humic and fulvic acids.
3. Agro.Bio preparations activate biochemical processes in plants, increasing yields and improving product quality.
4. The most effective form is the combination leonardite + Adept + NPK at doses of 1 t/ha for cereals and 2 t/ha for silage corn.