Salts vs. Chelates

Added on 08 March 2021

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Many foliar fertilizers on the market are inefficient at being taken up by the leaves for a number of reasons. Foliar fertilizers must be soluble in order to readily move through the cuticle. Additionally, many fertilizers on the market (such as humates and lignosulfonates) are restricted from uptake via the polar pores due to their relatively large molecule size.

Charged compounds such as salts (nitrates, chlorides, etc.) will interact with the inherently negative charge of the leaf surface, interfering with foliar uptake. Salt-based formulations also have a tendency to burn the crop. Chelation of metals with carbohydrate-based PAC neutralizes the charge of positively charged ions preventing tie-up on the leaf surface.

Using chelates to form true solutions is a more effective method for foliar fertilization. Chelates are compounds that bind to metals and form a strong, ring-like structure. A negatively charged ligand with multiple binding sides interacts with a positively charged nutrient ion, neutralizing the charge and forming a chelate. Chelates also prevent interaction with other ions in solution, they significantly improve solubility and compatibility in the tank, and they allow for improved uptake by the leaf.

In the crop vs. on the crop.

In the trial below, equal amounts of manganese were applied onto corn leaves. The leaf tips were harvested 3 days after spotting the product on a separate area. ManMax delivered significantly more manganese into the leaf and moved into unsprayed tissue. The high rate of the applied salt solution resulted in damage and caused burn on the leaf.