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Characterization of the Zinc Retained in Some Soils of India Using pH Gradient Elution
Author(s) -
Shukla U. C.,
Mittal S. B.
Publication year - 1980
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/sssaj1980.03615995004400010007x
Subject(s) - solubility , chemistry , zinc , loam , soil water , solubility equilibrium , extraction (chemistry) , reagent , precipitation , elution , adsorption , inorganic chemistry , nuclear chemistry , chromatography , geology , soil science , organic chemistry , physics , meteorology
Zinc retained in soils was characterized by studying its solubility characteristics in continuous elution with a pH gradient solution and equilibrium extraction in 1 N NH 4 OAc (pH 7.0), 1 N HCl and 6 N HCl, and relating these to the solubility characteristics of Zn(OH) 2 and Zn 3 (PO 4 ) 2 added to the soil. Zinc was retained in forms having low solubility throughout the pH range of 6.8 to 3.2. Solubility increased 5 to 15 times below pH 3.3. Equilibrium extraction of Zn by different reagents also showed that a large portion of the retained Zn was in slowly available forms. More Zn remained extractable in sand than loam at pH values > 4.0, however, more soil Zn was extracted in loam than sand at pH < 4.0. Solubility curves of Zn(OH) 2 and Zn(PO 4 ) 2 resembled the solubility curves of adsorbed Zn. The relationship as described by Lindsay and Norvell (4), [Zn 2+ ] ≅ 10 5 (H + ) 2 , did not seem to fit these soils. In this investigation the observed relationship was [Zn 2+ ] ≅ 10 4 (H) 0.1 . There was less change in Zn concentration with changes in pH between 6.8 and 4.0. Precipitation reactions, i.e. formation of Zn(OH) 2 and Zn 3 (PO 4 ) 2 , etc. in these soils of pH 8.3 and 8.4 predominated, particularly at high equilibrium Zn concentrations. Proportionally more Zn remained extractable at low than at high levels of Zn application.