Under certain circumstances iron deficiency in protected crops is difficult to control. FeEDDHA chelate can provide the solution.
Iron deficiency frequently affects protected crops such as
strawberries and causes the characteristic symptoms of interveinal
yellowing. In turn this results in yield losses and reduced
The basic cause is high pH of the substrate/nutrient solution
and associated increased bicarbonate levels. The problem is
exacerbated by poor quality irrigation water, periods of rapid
vegetative growth and, it is claimed, by the use of newer alkaline
substrates such as coir.
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.
A Technical Essentials bulletin providing more
information is available.