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Zinc Sorption, Desorption, and Fractions in Three Autoclaved Soils Treated with Pyrophosphate
Author(s) -
Xie R. J.,
MacKenzie A. F.
Publication year - 1990
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/sssaj1990.03615995005400010011x
Subject(s) - sorption , chemistry , desorption , soil water , cation exchange capacity , zinc , pyrophosphate , subsoil , environmental chemistry , fertilizer , nuclear chemistry , inorganic chemistry , adsorption , soil science , geology , organic chemistry , enzyme
Pyrophosphate (PP) is used as a P fertilizer. Unlike orthophosphate, PP can sequester soil Zn. In addition, PP sorption may affect Zn sorption and have implications for fertilizer practice. Pyrophosphate effects on Zn solubility were examined with autoclaved top‐ and subsoil samples from three Quebec soils. Soils were equilibrated sequentially with PP solutions, then with Zn solutions, and finally with solutions containing neither P nor Zn. The effects of PP sorption on soil cation exchange capacity (CEC), PP desorption, and Zn sorption and desorption were determined. Zinc from treated soils was extracted sequentially with KNO 3 (Zn KNO 3 ), NaOH (Zn NaOH ) and concentrated HNO 3 + H 2 O 2 (Zn HNO 3 ) solutions. One mmol sorbed P kg −1 as PP resulted in CEC increases of 0.52 to 0.89 mmol c kg −1 soil. Increased Zn sorption was equivalent to 7 to 12% of the increase in CEC induced by sorbed PP in the Uplands (Typic Haplorthod), and 0.3 to 2.8% in the St. Bernard (Typic Eutrochrept) and the Dalhousie (Typic Humaquept) soil samples. Sorbed PP reduced Zn desorption in the Uplands and St. Bernard soils but not in the Dalhousie soils. Positive correlations between sorbed PP and extractable Fe or Al materials, clay, and organic C suggested that PP sorption was related to surfaces of Fe materials (especially crystalline Fe), or clay‐organic complexes. Zinc addition improved correlations between desorbed PP and soil parameters. Added PP at 90 mmol P kg −1 soil reduced Zn KNO 3 , by about 50% (except with the Uplands subsoil), while added PP increased Zn NaOH and Zn HNO 3 in all soils, indicating that Zn sorption and PP‐Zn interactions were mainly related to Fe or Al oxides, and increased Zn sorption with PP was related to increased specific sorption sites.