The influence of mineral elements and humic preparations Agro.Bio on the yield of barley and winter wheat on chernozems of different fertility and mechanical composition

In the semi-arid climate of the Steppe, on ordinary chernozem soils, the application of phosphorus fertilizers is a highly effective measure for increasing the yield of most crops. However, in recent years, due to the increasing intensification of agriculture, the over-plowing of chernozem soils, the introduction of high-yielding varieties and hybrids, and the simultaneous reduction of fallow land and perennial grasses, all cultivated crops, especially winter wheat, have begun to respond to nitrogen fertilizers.

Results of field trials with fertilizers during the first years of irrigation in the Dnipro region of Ukraine showed contrasting results for the combined application of nitrogen and phosphorus. Nitrogen fertilizers were highly effective, while phosphorus fertilizers were ineffective. The greatest effect was achieved with a nitrogen-phosphorus, or complete, mineral fertilizer, where nitrogen predominated.

To determine the impact of individual nutrients on barley growth, development, and yield, depending on the natural fertility of chernozem soils with adequate moisture, a pot experiment was conducted with spring barley. The experiment included a variant with the addition of an organic stimulant based on humic acids. This variant was intended to determine the role of mobile humus in the absorption of mineral nutrients from the soil and fertilizers.

For the experiment, 5 varieties of ordinary chernozem were taken, differing in natural fertility and mechanical composition, from sandy to light clayey (Table 1).

Table 1. Physicochemical characteristics of ordinary chernozems

Humus content in the soils varied from 1.1 to 5.5%. The studied chernozems also differed in the content of gross and mobile forms of nutrients: the heavier the texture, the greater its humus, nitrogen, phosphorus, and potassium reserves. However, the availability and mobility of easily digestible nutrients, especially phosphorus and potassium, in chernozems is inversely related to texture and humus content. In sandy, light loamy, and medium loamy chernozems, phosphorus availability is 2-4 times higher than in heavy loamy and light clay chernozems.

Fertilizers were applied according to the experimental design before sowing, covering the entire soil volume in the container. A modern, similar humic preparation, Agro.Bio Potassium Humate, was used (the optimal application rate under field conditions is 2 l/ha). This environmentally friendly complex is made from high-quality leonardite and contains 15% humic acids, ballast-free phosphorus, and 100% bioavailable compounds. The preparation is chloride-free, stimulates root growth, and activates soil microflora even at low temperatures.

Table 2. Effect of fertilizers on barley yield and its structure

It should be noted that without fertilizer, barley plant growth and development were poor. A direct correlation was observed between black soil fertility and barley productivity. Under adequate moisture conditions, phosphorus alone is ineffective in most cases. On all studied black soils, barley responded strongly to nitrogen additions: grain yield increased 4-5 times compared to the control.

The use of Agro.Bio Potassium Humate, combined with a relatively high level of nitrogen-phosphorus-potassium nutrition, resulted in yield increases on all studied chernozems. Water-soluble forms of humic acids contributed to a more complete and economical use of mineral nutrients. On sandy chernozem, the highest grain yield increase was achieved with humate application.

Table 3. Effect of humic preparations on winter wheat yield

The quality of the barley crop (Table 4) was also determined by the presence of nutrients in the soil. Nitrogen-phosphorus-potassium fertilizers and their combination with Agro.Bio's Potassium Humate increase the nitrogen and phosphorus content of grain in poor and light loamy chernozems.

Table 4. Content of nitrogen, phosphorus and potassium in the barley yield (% of absolutely dry matter)

Table 5. Removal of N, P₂O₅ and K₂O by barley harvest

CONCLUSIONS

• Under conditions of sufficient moisture, nitrogen fertilization and its combination with phosphorus are crucial for ensuring high crop yields with good product quality. The use of phosphorus alone does not produce the desired effect.
• The use of water-soluble forms of humic acids in combination with NPK fertilizer improved barley growth and development and contributed to further yield increases. The magnitude of yield increases was inversely related to overall soil fertility.
• The introduction of mobile humic substances leads to a decrease in the consumption of nitrogen, phosphorus and potassium to form a unit of yield.

Agro.Bio Expert Note: Fundamental research on humic fertilizers, presented in this article, confirms the exceptional role of humic acids in unlocking soil fertility potential. Today, Agro.Bio is advancing this research, offering Ukrainian farmers modern biotechnological solutions based on leonardite. The use of highly concentrated products, such as Agro.Bio Potassium Humate (application rate: 2 l/ha), allows for the most effective mobilization of soil resources and guaranteed increased crop productivity, even in challenging climate conditions.