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Reactions of DTPA Chelates of Iron, Zinc, Copper, and Manganese with Soils
Author(s) -
Norvell W. A.,
Lindsay W. L.
Publication year - 1972
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1972.03615995003600050027x
Subject(s) - chemistry , chelation , manganese , soil water , zinc , copper , calcareous soils , nuclear chemistry , alkali soil , pentetic acid , salt (chemistry) , atomic absorption spectroscopy , inorganic chemistry , environmental chemistry , geology , organic chemistry , soil science , physics , quantum mechanics
The Fe, Zn, Cu, and Mn chelates and the Na salt of DTPA (diethylenetriaminepentaacetic acid) were reacted with suspensions of acid and alkaline soils. The suspensions were aerated and shaken continuously for periods of 2 hours to 30 days. The concentrations of soluble Fe, Zn, Cu, Mn, Ca, and Mg were measured by atomic absorption spectrophotometry, and the concentration of 14 C‐labeled DTPA was determined by a liquid scintillation technique. Additions of Fe‐DTPA were effective in maintaining soluble Fe in four soils ranging in pH from 5.8 to 7.3. Even at pH 7.9 more than 13% of added Fe remained soluble after 30 days of reaction in a calcareous soil. DTPA was an ineffective chelate for Zn and Cu in soils at pH 5.8 and 6.2, but became more effective with rising pH. In the alkaline soils more than 50% of added Zn and Cu remained soluble during 30 days of reaction. Essentially all Mn from Mn‐DTPA additions was lost from solution within 3 days in all soils. Discrepencies between the concentrations of 14 C‐labeled DTPA and soluble micronutrient metals suggest that an appreciable fraction of 14 C‐labeled DTPA decomposed to unknown products having different chelating capabilities.