Utah State University
Ferric iron rapidly precipitates as FeOH and becomes biologically unavailable, so chelated iron is commonly used in liquid fertilization systems to keep it in solution. The most common chelating agents in agriculture are:
- EDDHA (ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)
- DTPA (diethylenetriaminepentaacetic acid)
- EDTA (ethylenediaminetetraacetic acid)
- and for monocots in deep-flow hydroponics, HEDTA (also called HEEDTA)
Fatzinger, Brendan and Bugbee, Bruce, "Residue from Sequestrene 138 Fe EDDHA Clogs Filters: Alternatives for Chelated Iron in Liquid Fertilizer Systems" (2021). Nutrients. Paper 8.