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Chemical significance of aluminium extracted from three horizons of an acid forest soil, using chloride salt solutions
Author(s) -
PONETTE Q.,
ANDRE D.,
DUFEY J.E.
Publication year - 1996
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.1996.tb01375.x
Subject(s) - chemistry , salt (chemistry) , aluminium , chloride , lime , soil ph , extraction (chemistry) , soil water , inorganic chemistry , nuclear chemistry , chromatography , soil science , geology , paleontology , organic chemistry
Summary Aluminium is usually important in exchange reactions in acid soil, but amounts extracted are strongly affected by procedure. We examined the impact of proton release, following salt addition, on Al removal from three horizons (Oe, Oa and A 12 ) of an acid, brown forest soil. The Al was first extracted with either 1 M KC1, 1 m NH 4 C1 or 0.5 m CuCl 2 on the three horizons limed to pH 5.5. For any lime addition, both the pH drop following salt addition and the amounts of extracted Al were greater with CuCl 2 than with KC1 or NH 4 C1. For the Oa and A 12 horizons there was a single inverse linear relation between amount of Al extracted and the pH of final extract, independent of the extracting cation. In the Oe horizon CuCl 2 extracted constant amounts of Al, whereas the quantity of Al removed by KC1 or NH 4 C1 increased linearly as pH declined below pH 3.6. Extra Al was mobilized following unbuffered KC1 extraction, a side effect induced by the extracting procedure itself. Al mobilization increased with increasing H + additions. In the Oe horizon, equilibrium was established rapidly (≤ 24 h), and decreasing the pH of the soil‐KCl suspensions to 2.0 resulted in extracted Al amounts equal to or slightly greater than those obtained with CuCl 2 solutions. Al amounts extracted with acidified KC1 solutions from the A 12 were close to those obtained using CuCl 2 solutions at similar pH in the extract. In the samples from the A 12 layer, increasing the equilibration time resulted in increasing proton consumption and equivalent release of Al ions in the extract.