Chelated micronutrients
EDTA-Fe and related chelates solve a real problem in alkaline soils. How chelation works, and the honest answer on whether it is natural.
The problem chelation solves
Iron, manganese, zinc and copper are essential micronutrients, and in neutral to alkaline soils they are largely unavailable — iron in particular precipitates as insoluble hydroxides and oxides above about pH 7. A soil can contain abundant iron while the crop shows severe chlorosis. Applying iron sulfate to such a soil often fails, because the iron precipitates before it reaches the root.
A chelate is a molecule that binds a metal ion in a ring structure, keeping it soluble and protected from precipitation until it reaches the plant, where it is released.
The chelates and their working range
EDTA is the most common and the one used in this range, as EDTA-Fe. It is effective and inexpensive but its stability falls away above roughly pH 6.5, so in strongly alkaline soils it releases iron prematurely.
DTPA is stable to around pH 7.5, and EDDHA to pH 9 and above — which is why EDDHA is the standard choice for calcareous soils despite its higher cost. A product formulated with EDTA-Fe is well suited to acid and neutral conditions and less so to high-pH soils, and that is useful, specific information for a grower.
Amino acid and organic acid chelates — citrate, gluconate, and amino-acid complexes — are weaker but genuinely useful for foliar application, where soil chemistry is not the constraint and lower molecular weight aids uptake. Several products in the range use citric acid and glutamic acid in this role.
Is a chelate natural? The honest answer
EDTA is a synthetic aminopolycarboxylic acid. It is not naturally derived, it is poorly biodegradable, and it is persistent enough in water to have attracted environmental attention as a mobiliser of metals in aquatic systems. Describing an EDTA-chelated product as naturally derived is not defensible.
Natural chelation does exist — plants secrete siderophores and organic acids to mobilise iron, and amino acid and citrate complexes mimic that. Those are the natural analogues, and they are weaker. A product range positioned around natural inputs is better served by explaining that trade-off honestly than by blurring it, and this page is where that explanation belongs.
What does chelated micronutrients not do?
They do not add micronutrients that are absent, only make present ones available. They do not work outside their pH stability range. And over-application of strong chelates can mobilise unwanted metals as readily as wanted ones.
Where does chelated micronutrients appear in the range?
EDTA-Fe appears in Micro Boost, Nitrogen Pro, NPK Pro and Vega Pro. Micro Boost also uses glutamic and citric acids, and most products in the range include citric acid.