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Influence of Sorbed Hydroxyl and Sulfate on Neutralization of Soil Acidity
Author(s) -
Mehlich A.
Publication year - 1964
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/sssaj1964.03615995002800040014x
Subject(s) - chemistry , neutralization , sulfate , inorganic chemistry , soil water , oxide , sorption , covalent bond , coordination sphere , ion , mineral , salt (chemistry) , cation exchange capacity , soil ph , adsorption , geology , organic chemistry , soil science , antibody , immunology , biology
Soils of varying clay mineral characteristics were treated with anion‐exchange resin to obtain systems containing either sorbed OH ‐ or SO 4 2‐ . They were then equilibrated with Ca(OH) 2 , and the neutralization of acidity consisting of permanent charge (Hp), variable charge (Hv) and anion‐exchange (Han, principally SO 4 2‐ absorbed) evaluated. The order of neutralization was Hp (consisting principally of Al 3+ except in the case of the muck) first, followed virtually simultaneously by Hv and Han. Sorbed SO 4 2‐ resulted in more strongly acidic systems. Hv is postulated to arise from covalently‐bonded H of aquo groups in the coordination sphere of hydrated Al (or possibly Fe 3+ atoms). The source of Han is postulated to be acid radicals substituted for OH groups, likewise in the coordination sphere of Al and Fe 3+ associated with clay surfaces or in hydrous oxide crystals. The magnitude of Han, the soil acidity due to sorbed acid radical anions, may be an appreciable part of the total acidity of Red‐Yellow Podzolic and Reddish‐Brown Lateritic soils.