The aim of foliar feeding of winter wheat is to ensure a balance of mineral nutrition, since this measure directly affects the formation of the quantitative parameters of the most important yield components. The main role in forming them is of course played by plant nitrogen supply, and its uptake level and the productivity of photosynthesis depend on the balance of plant mineral nutrition as a whole.
If winter cereal crops show no clearly expressed signs of deficiency of individual nutrients, this does not yet mean that plants do not need them applied by foliar feeding. Weather conditions at this time often hinder the supply of various mineral nutrients to plants, in particular phosphorus, whose content in the soil may be sufficient, but low temperatures and a dried-out topsoil inhibit uptake of this important element through the root system. Insufficient phosphorus nutrition significantly reduces photosynthetic productivity and is often visible to the naked eye as a violet colour of leaves.
How can the situation be corrected?
The simplest way is foliar feeding with phosphorus in the form of phosphite. The main advantage of phosphite is quick penetration into the plant and a high level of uptake. Phosphorus in the form of phosphite stimulates the plant's synthesis of phytoalexins, substances that neutralize foreign infection, which is a manifestation of the fungicidal action of this compound.
On eroded, light soils, because magnesium is leached deep into the soil profile and because of unbalanced nutrition with nitrogen predominating, signs of magnesium starvation of plants may appear as paling of the leaf surface, which reduces photosynthetic productivity.
During the 2016–2017 winter wheat growing season ECOORGANIC carried out a number of field trials of foliar feeding systems in different natural and climatic zones and at contrasting levels of basic fertilization. On a field with a low level of basic fertilization and moisture deficit in the Steppe zone, a field trial with different levels of foliar feeding was carried out in comparison with the control (no foliar feeding).
The first assessments in the trial variants were done on 5 May 2017, 22 days after foliar feeding with fertilizers with phosphorus in the form of phosphites. The photo clearly shows the difference in plant development on the trial plots and control plots. Plants from plots where the level of phosphite feeding was higher had more evenly developed stems and a greater mass and leaf surface area.
Feeding with compositions containing L-α amino acids and microelements
To reduce the effect of stress caused by moisture shortage, at the flag leaf formation stage crops were fed with compositions containing L-α amino acids and complex compositions containing microelements: ECOLINE Universal Growth (Amino) with a minimal microelement content and L-α amino acids (variant 1), ECOLINE Magnesium (Chelates) (variant 2) with increased magnesium and chelates of other microelements as 100% EDTA chelate, and ECOLINE Cereal (Chelates) (variant 3) with high nitrogen and potassium and microelements as 100% EDTA chelates.
At the start of grain formation, feeding was done with ECOLINE Cereal (Chelates) (variant 1), ECOLINE Cereal (Chelates) + ECOLINE Phosphite (K) (var. 2), ECOLINE Cereal (Chelates) + ECOLINE Phosphite (K-Amino) (variant 3), but because of severe drought no effect from the last feeding was obtained. The effect of different feeding variants of winter wheat plants on the formation of individual plant productivity indicators was determined on 30 June (table 1).
Thanks to pre-sowing seed treatment and spring foliar feeding at tillering, the foliar feeding scheme of the first variant ensured a rise in field emergence of plants and thus sowing density by 25%, and with phosphorus in the form of phosphite added to the seed treatment, by 30% (var. 2, 3). Spring feeding with phosphorus in the form of phosphite stimulated development of the root system and aboveground part of plants and promoted growth in the number of productive stems of 33–40%.
The yield from each variant was harvested separately by direct combining and weighed at the farm's grain yard. The effect of using foliar feeding fertilizers in this experiment showed that even in such difficult conditions a yield gain over the control was obtained in all variants, in the range of 18.8–31.3%. The highest yield gain of 31.3%, 8.12 c/ha, was obtained in the first variant.
The financial results of this field trial are given below.
Economic efficiency of using Ecoorganic fertilizers
Calculation of the economic efficiency of using fertilizers from ECOORGANIC showed that even under drought and minimal basic fertilization, all variants compared with the control gave additional income in the range of USD 61.27–90.79/ha.
In the Polissia zone (Korets district of Rivne region), under balanced basic fertilization and sufficient moisture supply, sowing in all variants during the growing season, including the control, was done with treated seed according to the same scheme. In spring, plants on the control plots were not fed by foliar application, and in the two other variants feeding was carried out according to the scheme given in the table.
Sufficient moisture and main microelement supply promoted the formation of almost twice as high a yield level in the control variant compared with the previous trial, but in this case too a significant effect of foliar feeding on the formation of structural elements and the yield itself is evident. The highest grain yield gain, 11.3 c/ha, was obtained in variant 2, which is 21.3% of the control. The economic efficiency calculation showed that the additional income in the first variant was USD 44.19/ha, and in the best variant USD 118.91/ha.