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THE MOBILIZATION OF IRON BY AQUEOUS EXTRACTS OF PLANTS
Author(s) -
MUIR J. W.,
LOGAN J.,
BOWN C. J.
Publication year - 1964
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1964.tb02221.x
Subject(s) - chemistry , phosphoric acid , fraction (chemistry) , aqueous solution , calcium hydroxide , ferric , hydroxide , ferrous , inorganic chemistry , composition (language) , organic acid , tetrabutylammonium hydroxide , nuclear chemistry , organic chemistry , linguistics , philosophy
Summary The organic‐acid fraction maintains iron in solution from pH 4 to at least pH 9.5, with a maximum of 15 mg iron per gram of dried pine needles at pH 8; the amino‐acid fraction is inactive above pH 4.5. The constituents of the organic‐acid fraction are examined individually and their effectiveness com‐pared. Of the active acids, all except phosphoric acid are α‐hydroxy carboxylic acids. A synthetic solution, with a composition that corresponds to the analysis of the organic‐acid fraction, is used to demonstrate that all the major active constituents have been identified. The activity of the individual acids and the organic‐acid fraction is due to their ability to form water‐soluble complexes with iron and to stabilize ferric hydroxide sols. The water‐soluble complexes are formed over a wide range of pH and in the presence of calcium ions. The formation of ferric hydroxide sols, however, is greatly influenced by pH and by the presence of calcium ions. These findings are related to soil processes and to the morphological character of the soils on which Scots Pine trees normally grow.