Foliar Fertilizers
Foliar fertilizer is a fertilizer product which is designed to be applied directly to the leaves of a plant. Foliar fertilizers act more quickly, and far more efficiently, as most of the fertilizer ends up in the plant, rather than in the soil.
Please comment on the use of Foliar Fertilizers, and also can I use only foliar fertilizer instead of the solid/Granular ones.
Foliar fertilizers are indeed extensively used to supply plats with nutrients the world over. In general, plants have the capacity to take up nutrients either through the leaf tissue or through the plant roots ( By diffusion, Osmosis or Interception by plant roots).
The principle route to use to supply the nutrients will depend largely on the relative amounts of the nutrients needed by the crop.
The efficiency with which the foliar-applied nutrients can be taken up and utilized by the crop will depend on the relative mobility of the particular Nutrient.
The movement of these nutrients is mainly through the plants phloem tissue, through which the nutrients are conveyed to the sites where they are needed for optimum plant or cellular function. So, for nutrients that are mobile within the plant, such as Nitrogen and Potassium, a foliar application would be okay in delivering them to the various plant parts.
However, for nutrients such as Calcium, Sulphur or Iron that are very immobile in the plant, a foliar application will not be effective in delivering them to where they are most required.
In Tomatoes for example, applying Calcium as foliar may still result in Incidences of Blossom End Rot despite having supplied the required calcium. This is because the calcium will tend to be concentrated in the leaves and does not move into the fruits where its required to prevent Blossom End Rot.
Besides Nutrient mobility, perhaps the most important consideration
should be the amounts of the nutrients required by the crop. The Major plant Nutrients – N, P, K,- as well as the secondary nutrients Ca, Mg and S, are required in relatively large amounts by crops, such that a foliar route would not supply the needed amounts.
These Nutrients must be supplied principally through the soil or other media for root uptake. Micro-nutrients on the other hand , including Zn, Cu, Fe, Mn etc are critical for plant production, but required in relatively low amounts. These can therefore be efficiently applied through Foliar fertilizers .
Hidden Hunger
It is important to note that plants may suffer from certain nutrient deficiencies even though this may not physically be manifested yet. This is especially so for the Micro-nutrients and already begins to compromise yield.
For this reason, its recommended to apply the micro-nutrients as a foliar and prevent full-blown deficiencies. For effective use of the foliar products, use spreaders and stickers to ensure even application of the product on the leaves and prevent the product from easily washing off the leaf surface.
By: Vitalis Wafula
East Africa Regional Agronomist
Yara
