Dissolution of Iron from Iron (Hydr) Oxides by Mugineic Acid

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Mugineic acid (MA; (2S, 2'S, 3'S, 3"S)-N- [3-carboxy-3-(3-carboxy-3-hydroxy-propylamino)-2-hydroxypropyl]-azetidine-2-carboxylic acid), a multidentate complexing agent, is exuded by the roots of graminaceous plants (e.g. barley) growing under Fe-deficient conditions. The nature of the interactions of MA with Fe (hydr)oxide minerals in soils is thus of considerable practical imporinvestigated the amounts of Fe dissolved from 24 samples of Fe (hydr)oxides by 100 μM MA (Fe_<MA>) and 200 mM NH_4-oxalate (Fe_o). The Fe_o values were much larger than the Fe_<MA> ones, though the crystal linity of the Fe (hydr)oxides was a significant factor. For Fe (hydr)oxides consisting of goethite, hematite, ferrihydrite, and their mixture, FeMA increased With the increase of Feo, indicating that Fe_<MA> would be correlated with Fe_o, that is ithe amount of short-range ordered Fe minerals including ferrihydrite. For goethite, hematite, magnetite, maghemite, and lepidocrocite with a high crystallinity, MA was relatively ineffective in dissolving Fe, although a part of crystalline magnetite, maghemite, and lepidocrocite could be dissolved by NH_4-oxalate. For soils containing significant amounts of magnetite, maghemitc, lepidocrocite, it is unlikely therefore that Feo would be a useful indicator of plant-available Fe.
社団法人日本土壌肥料学会の論文