Foliar sprays dry quickly when applied at high temperatures, reducing absorption of the nutrients in solution.
High light intensities can improve foliar uptake.
High humidity favours nutrient uptake through the leaves in two ways; by decreasing the rate of drying of the applied nutrient solutions, and by causing the cuticle to absorb water from the atmosphere and swell, which results in the formation of more polar pores.
pH of the Spray Solution
The pH of the spray solution can influence solubility, uptake and penetration of the plant nutrients.
Wetting agents improve foliar uptake by enhancing leaf coverage. Surfactants reduce the surface tension of the solution, overcoming cuticular barriers and improving foliar uptake.
Aging leaves develop thick cuticles that hinder foliar uptake.
Young developing leaves have thin cuticles and are therefore more efficient at foliar uptake.
Higher spray volumes result in more uniform coverage and more effective foliar feeding.
Foliar applications should wet the entire canopy, especially the new leaves.
As the concentration of the foliar spray increases, uptake also increases.
Lower spray water volumes generally result in less uniform spray coverage and less effective foliar feeding.
Ambient and spray water temperatures can interact with these factors.
In the soil, nutrients interact with one another leading to changes in availability to plants. The figure below (Mulder’s Chart) displays the various interactions that can occur. Antagonism: High levels of a particular nutrient in the soil can interfere with the availability and uptake of other nutrients. For example, high nitrogen levels can reduce the…
Nutrients must come in contact with the root surface in order to be absorbed by the root. There are three ways in which soil nutrients can reach the root surface: diffusion, mass flow and root interception. Diffusion The movement of nutrients in the soil solution along a concentration gradient. As crops take up nutrients, an…
Give crops the strength to cope with dry conditions. The Problem: When it’s hot and it hasn’t rained for weeks, how do your crops cope? During times of low water supply, the stomata on the leaves close to prevent water loss. This helps to conserve water in the leaves but it also disrupts the water…
Why Foliar Feed? Foliar feeding is a powerful way to provide crops with essential micronutrients throughout the growing season. When done properly, foliar fertilization can be more target oriented compared to soil-applied methods, since nutrients can be delivered directly to plant tissue during critical stages of plant growth. Although it doesn’t replace soil nutrition, foliar…
pH is defined as the negative log of the hydrogen ion (H+) concentration on a scale of 0 to 14. The neutral point is 7, less than 7 is acidic and greater than 7 is alkaline or basic. The acidification of soils is the result of natural soil processes and is enhanced by cropping and…
Uptake of foliar-applied nutrients. The cuticle provides plants a layer of protection surrounding their stems, leaves, fruits and flowers, which can be compared, in many ways, to our skin. The function of this cuticle is to control the flow of gases in and out of the plant and to maintain optimal levels of transpiration (the…