In soils with pH above 7.5, Fe-EDTA becomes chemically unstable; the iron ion dissociates and precipitates as insoluble iron hydroxide (
F
e
(
O
H
)
3
Fe(OH)
3
), rendering it unavailable to plant roots.
Iron: You must apply Fe-EDDHA (ortho-ortho isomer content minimum 4.8%). EDDHA chelates remain 100% stable in alkaline substrates up to pH 10.0.
Zinc: Use Zn-EDTA (12%), which remains stable in alkaline soils up to pH 8.5, or perform foliar applications of liquid chelated zinc during active flush stages.
Standard brands supplying genuine Fe-EDDHA 6% in India include Aries Ferroche, Valagro Ferrilene, and BASF Librel.
Input dealers and agrochemical suppliers: join the discussion on the Plant Finder app on Google Play to list your soil amendment solutions.