[2] Near neutral pH, the principal complex is [Fe(EDTA)(H2O)]−, although most sources ignore the aquo ligand.

Provided the nutrient solution in which the [Fe(EDTA)(H2O)]− complex will be used has a pH of at least 5.5, all the uncomplexed iron, as a result of incomplete synthesis reaction, will still change into the chelated ferric form.

In the absence of EDTA or similar chelating agents, ferric ions form insoluble solids and are thus not bioavailable.

[5] Iron chelate is commonly used for agricultural purposes to treat chlorosis, a condition in which leaves produce insufficient chlorophyll.

[7] According to Jacobson (1951),[2] the stability of ferric EDTA was tested by adding 5 ppm iron, as the complex, to Hoagland's solution at various pH values.

In addition to Jacobson's original recipe and a modified protocol by Steiner and van Winden (1970),[4] an updated version for producing the ferric EDTA complex by Nagel et al. (2020)[8] is presented in Table (1).