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Influence of Phosphate Fertilization on Zinc Adsorption by Tropical Soils
Author(s) -
Saeed M.,
Fox R. L.
Publication year - 1979
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/sssaj1979.03615995004300040011x
Subject(s) - sorption , soil water , adsorption , zinc , phosphate , chemistry , freundlich equation , phosphorus , fertilizer , human fertilization , mineralogy , inorganic chemistry , environmental chemistry , soil science , geology , agronomy , organic chemistry , biology
Zinc adsorption isotherms were constructed for five soils from Hawaii which varied in mineralogy and history of phosphate fertilization. Equilibrating conditions were: 25°C, 0.01 M CaCl 2 , soil solution ratio of 1:10, and 6 days. The amount of Zn added ranged from 0 to 600 µg/ml as ZnSO 4 · 7H 2 O. Equilibrium was reached by 72 hours. Unfertilized soils which contained predominantly constant charge colloids absorbed more Zn than soils with variable charge colloids. Phosphorus fertilization increased Zn adsorption by soils that contained colloids predominantly of the variable charge type. The results support the hypothesis that phosphate additions to soils increase Zinc adsorption by increasing the negative charge on iron and aluminum oxide systems. For soils containing constant charge colloids, prior P applications decreased Zn sorption because the fertilizer contained Zn as an accessory element. Zinc sorption conformed to the Freundlich model at concentrations greater than 0.1 ppm Zn in solution.