UK: Paper on the special role of FeEDDHA in protected crops
As pH rises above about 6.0 elemental iron is made increasingly unavailable because of precipitation. Because of their chemical stability EDTA and DTPA iron chelates have been used successfully for many years to overcome the problem.
Bicarbonate ions occur naturally under high pH conditions and are produced by plant roots. High concentrations of bicarbonate ions interfere with the natural process of iron uptake by roots. The chemical stability of FeEDTA and FeDTPA chelates is also affected making them less effective.
The problem is easily overcome by substituting with the more robust FeEDDHA. This chelate is unaffected by bicarbonate and has a very wide pH stability range.
Remember though that the solubility (at high concentrations) of FeEDDHA is reduced when the solution pH is less than 4.0 (approx.) so add the chelate to the non-acidified “A” or “Calcium” tank.
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