How Should Foliar Fertilization Be Done?

Plants take the macro and micro nutrients they need from the environment they grow in through their roots throughout their vegetation. However, due to various reasons originating from the physical, chemical and biological properties of the soil, sometimes deficiencies are observed in the uptake of these nutrients. In such cases, foliar application is a fertilization technique that is frequently preferred and provides positive results when applied properly. FIXAMIN brand that we developed within the OLIMPUM, which I have been consulting for about 2 years, has been a good example of such applications.

Although there are differences from plant to plant, stomata (pores) located on both surfaces of leaves are the parts of plants that basically function in gas exchange, and since there is a certain air pressure inside them, it is quite difficult for water and nutrients dissolved in water to pass through the stomata. Nutrients applied to leaves in water-dissolved form pass through the threadlike tubes (Ectodesmata) and intercellular spaces (intercellular spaces) in the cuticle layer on the outer surfaces of the leaves, reach the plant cells and participate in metabolism. Ionic diameters and ion charges are of great importance in the passage of nutrients dissolved in water from the leaf.

Figure 1. View of Ectodesmata and stolamar (Franke, W. 1971).

Figure 2. Vertical section of leaf tissue (Alshaal, T., and El-Ramady, H. 2017)

There are various points to be considered in order to obtain the expected positive results from foliar applications.

• First, it is necessary to observe the deficiency of the nutrient element to be applied in the plants or to determine the hidden deficiency with leaf analyses. It is not beneficial to apply a nutrient element that is not deficient in the plant from the leaf.
• In order for nutrients to be taken from the leaf, they must be dissolved in water. Therefore, it is important for the leaf surfaces not to lose their wetness as much as possible after application. Therefore, application should be made in the evening hours when the sun has lost its effect.
• The transfer rates of plant nutrients from the leaves vary. While nitrogen in the form of urea is the fastest, boron is one of the slowest. Since the amount of plant nutrients that can pass through the leaves is quite limited, it would be more appropriate to apply microelements with this method except in special cases.
• In order to obtain the expected effects from the application, attention should be paid to issues such as repeating the application three or four times at 7-10 day intervals, carefully determining the application dose, using spreader-adhesive, making the water droplets as small as possible, and applying under windless conditions.

Prof. Dr. Murat Ali TURAN

RESOURCES

Franke, W. (1971). The entry of residues into plants via ectodesmata (ectocythodes). In: Gunther, F.A., Gunther, J.D. (eds) Residue Reviews / Rückstands-Berichte. Residue Reviews, vol 38. Springer, New York, NY.

Alshaal, T., & El-Ramady, H. (2017). Foliar application: from plant nutrition to biofortification.