The influence of humic fertilizers on corn yield in the conditions of the Zaporizhzhya region
Considering the growing need from year to year for additional reserves to increase crop yields, in particular, through the use of humic fertilizers.
Long-term experiments with the use of humic fertilizers on various agricultural crops and tree plantations in a number of regions of Ukraine have shown positive results.
Experiments with the use of Adept and potassium humate on ordinary chernozems of the central part of the Zaporizhia region were carried out in 2018-2020 at the Zaporizhia regional agricultural experimental station, as well as in different areas within the region.
The area where the experiments were conducted is an ordinary low-power, low-humus chernozem with the following agrochemical parameters (Table 1).
Table 1. Chemical composition of the soil
| Horizon, cm | Humus, % | Nitrogen, mg/100 g soil | Absorbed bases, mg-eq/100 g of soil | K₂O, mg/100 g soil | P₂O₅, mg/100 g soil | |
|---|---|---|---|---|---|---|
| Nitrate | Hydrolyzable | |||||
| 0-16 | 3.84 | 6.25 | 10.0 | Ca | 39.0 | 7.8 |
| 25-35 | 3.70 | Traces | 10.3 | Mg | 44.7 | 7.14 |
According to its mechanical composition, the soil is classified as heavy and medium loamy chernozem. The upper horizon is slightly dispersed and poorly structured. The maximum molecular moisture capacity is 12-16%. The soil reaction is almost neutral (pH of the water extract 6.8-6.9).
The article presents the results of two- and three-year studies on the use of Adept and potassium humate as fertilizers for corn.
Research methodology
The experiments were conducted on plots with deep autumn plowing; the predecessor of corn was winter wheat. Fertilizers were applied according to the experimental scheme: Adept — directly during corn irrigation, potassium humate — as a solution of 2 liters per 100 liters of water per 1 hectare, by spraying plants three times in the phases of: 4-5 leaves, at a plant height of 50-60 cm, and also during the period of crown emergence and cob formation. In the control variant, plants were sprayed with clean water in the same amount as with the potassium humate solution. The experiments were repeated three times.
The research program included:
- phenological observations and records;
- determination of nutrient and moisture reserves in the soil;
- analysis of physiological parameters;
- observations of plant growth and development.
The harvest was taken into account using the continuous harvesting method.
Research results
Observations showed that corn plants treated with humic fertilizers were distinguished during the growing season by more intense leaf coloring and overall development power compared to other experimental variants. This was especially noticeable with foliar fertilization with a potassium humate solution.
Analyses conducted by the station's plant physiology laboratory in 2021 showed that foliar application of potassium humate contributed to higher pigment content in corn leaves compared to the control (Table 2).
Table 2. Effect of foliar feeding with potassium humate on the pigment content in corn leaves (mg/g raw material)
| Date | Option | Chlorophyll A | Chlorophyll B | Carotene |
|---|---|---|---|---|
| 30.06 | Experienced | 1,870 | 1,256 | 0.621 |
| Control | 1,527 | 0.994 | 0,500 | |
| 21.07 | Experienced | 1,920 | 0.683 | 0.481 |
| Control | 1,736 | 0.628 | 0.472 | |
| 22.08 | Experienced | 1,200 | 0.609 | 0.290 |
| Control | 1,100 | 0.534 | 0.235 |
The most significant difference was observed in the content of chlorophyll A. During the vegetation period, all plants (experimental and control) gradually decreased the content of chlorophyll A, chlorophyll B and carotene, probably due to their destruction during the aging of plants, accelerated by dry conditions. However, when treated with potassium humate, this process proceeded more slowly, indicating a protective effect of foliar feeding, promoting more active synthetic activity of leaves.
This conclusion is supported by the data on the content of soluble carbohydrates and vitamin C in corn leaves (Table 3).
Table 3. Effect of foliar feeding with potassium humate on the content of carbohydrates and vitamin C in corn leaves
| Date | Option | Vitamin C, mg% | Reducing sugars, % | Sucrose, % |
|---|---|---|---|---|
| 30.06 | Experienced | 168.0 | 0.28 | 1.06 |
| Control | 71.2 | 0.30 | 0.94 | |
| 21.07 | Experienced | 24.0 | 0.99 | 1.05 |
| Control | 17.4 | 0.78 | 1.01 | |
| 22.08 | Experienced | 80.66 | 0.58 | 1.46 |
| Control | 62.33 | 0.49 | 1.36 |
Foliar feeding with potassium humate contributed to a slight increase in the carbohydrate content and a significant increase in the ascorbic acid (vitamin C) content in the leaves, especially in the first half of the growing season. This pattern persisted until the end of the crop development. The increased content of ascorbic acid, which participates in oxidation-reduction reactions, indicates the activation of these processes in plants treated with potassium humate.
Physiological and biochemical studies show that treatment of corn with potassium humate activates the synthetic activity of leaves, which leads to an increase in yield (Table 4).
Table 4. Effect of foliar feeding with potassium humate on corn yield (c/ha)
| Experimental variant | Grain yield, c/ha | Grain yield, c/ha | Increase, c/ha |
|---|---|---|---|
| Three-fold spraying of 2 liters per 100 liters of water per 1 hectare with a solution of potassium humate | 105.92 | 89 | 10.16 |
| Control (spraying with clean water) | 95.76 | 63.56 | 25.44 |
The use of Adept during corn sowing was also found to be effective (Table 5).
Table 5. Key plant productivity elements and corn yield (2018-2020)
| Experimental variant | Year | Plant height, cm | Average number of ears per plant | Grain yield from one cob, g | Absolute weight of grain, g | Grain yield, c/ha | Yield increase, c/ha |
|---|---|---|---|---|---|---|---|
| Control (without fertilizers) | 2018 | 192.3 | 1.20 | 155.3 | 294.7 | 94.4 | 0 |
| 2019 | 156.7 | 1.10 | 104.9 | 265.4 | 47.2 | 0 | |
| 2020 | 192.8 | 1,12 | 152.9 | 296.5 | 91.4 | 0 | |
| Average | 180.6 | 1.14 | 137.7 | 285.5 | 77.6 | 0 | |
| Humus + P₂O₅ in a mixture (2:1) | 2018 | 185.5 | 1.30 | 164.0 | 309,0 | 105 | +10.6 |
| 2019 | 155.0 | 1.06 | 109.3 | 267.6 | 50.8 | 0 | |
| 2020 | 191.2 | 1.14 | 154.9 | 300.3 | 95.2 | +0.8 | |
| Average | 177.2 | 1.17 | 142.7 | 292.3 | 83.6 | 0 | |
| Adept, equated to P₂O₅ | 2018 | 183.9 | 1.20 | 155.0 | 294.9 | 101.6 | +7.2 |
| 2019 | 157.3 | 1.10 | 105.6 | 261.3 | 49 | 0 | |
| 2020 | 197.1 | 1.16 | 158.1 | 304.4 | 98.6 | +4.2 | |
| Average | 179.4 | 1.15 | 139.6 | 286.9 | 83 | 0 | |
| P₂O₅ in granulated superphosphate (4-5 cm from seeds) | 2018 | 185.2 | 1.30 | 156.2 | 292.0 | 96 | +1.6 |
| 2019 | 158.5 | 1.08 | 107.8 | 261.2 | 46 | 0 | |
| 2020 | 188.0 | 1.10 | 156.8 | 294.3 | 99 | +4.6 | |
| Average | 177.2 | 1.16 | 140.3 | 282.5 | 80.2 | 0 | |
Humic fertilizers had a positive effect on the growth of aboveground mass of corn plants (Table 6).
Table 6. Effect of Adept on corn air dry weight gain (2020)
| Experimental variant | Time of sampling | Air-dry weight of 10 plants, g | Weight to control, ± g | Percentage of weight gain relative to the first control weight |
|---|---|---|---|---|
| Control (without fertilizers) | 30.06 | 280 | 0 | --- |
| 5.10 | 4830 | 0 | 17.2 | |
| Humus + P₂O₅ in a mixture (1:2) | 30.06 | 330 | +50 | --- |
| 5.10 | 4300 | -530 | 15.4 | |
| Adept, P₂O₅ equivalent | 30.06 | 430 | +150 | --- |
| 5.10 | 5200 | +370 | 18.6 | |
| P₂O₅ in granulated superphosphate (4-5 cm from seeds) | 30.06 | 260 | -20 | --- |
| 5.10 | 4350 | -480 | 15.5 |
Already on the 45-46th day from the emergence of corn shoots, the greatest increase in mass (15 g per plant) was observed in plots fertilized with Adept. By the end of the growing season, this increase reached 37 g versus 5 g in the variant with an organo-mineral mixture compared to unfertilized plots.
Research has also shown that the introduction of Adept contributed to water savings during the growth and development of corn. For example, in 2019, during the growing season (from September 30 to October 16), water consumption in plots with Adept was 369.7 mm versus 376-378.1 mm in other variants. On average, over three years, water consumption in plots with Adept was 375.3 mm versus 378.1-383.7 mm in other variants.
These data are confirmed by the results in the conditions of the farm. Using Adept and potassium humate in combination with other organo-mineral fertilizers, high corn yields were obtained annually. Despite the unfavorable weather conditions of 2021, the farm grew a corn grain yield of 82.6 c/ha on an area of 100 hectares.
Conclusions
- Humic fertilizers applied to ordinary chernozems of the central and north-eastern parts of the Zaporizhzhya region have a positive effect on increasing the grain yield and above-ground mass of corn, especially with foliar feeding with a solution of potassium humate.
- The amount of yield increase depends on weather conditions and moisture reserves in the soil. The average increase in corn grain yield over three years from Adept is 7.2 c/ha, from potassium humate (over two years) - 4.2 c/ha.
- Humic fertilizers activate physiological processes, primarily the synthetic activity of leaves, which leads to an increase in grain yield and mass.
- Mass application of Adept in the conditions of Zaporizhia region can be economically advantageous if the cost of application of 1 liter of Adept does not exceed the cost of 0.5 tons of semi-rotted manure. For final conclusions on the use of potassium humate, research should be continued.