The solubility characteristics of organic Al precipitates in allophanic Bshorizons could mimic those of Al hydroxides, and indicate the solubility of associated allophanes

Authors
Citation
Vc. Farmer, The solubility characteristics of organic Al precipitates in allophanic Bshorizons could mimic those of Al hydroxides, and indicate the solubility of associated allophanes, EUR J SO SC, 50(4), 1999, pp. 713-715
Citations number
13
Categorie Soggetti
Agriculture/Agronomy
Journal title
EUROPEAN JOURNAL OF SOIL SCIENCE
ISSN journal
13510754 → ACNP
Volume
50
Issue
4
Year of publication
1999
Pages
713 - 715
Database
ISI
SICI code
1351-0754(199912)50:4<713:TSCOOA>2.0.ZU;2-0
Abstract
It is shown that Al-humate and fulvate precipitates in Bs horizons of pH > 4.6 can be the source of the soluble aluminium which is rapidly released in equilibrium studies to give log(10){Al3+} + 3pH values near 9.4 at 8 degre es C, so that it is not necessary to postulate an anomalously reactive but sparingly soluble Al(OH)(3) phase. These Al-organic precipitates will have reached equilibrium in the natural soil environment with the more slowly re acting hydroxy-aluminium precipitates present, including proto-imogolite al lophane, but can release Al3+ much more rapidly than the inorganic precipit ates in laboratory equilibrations and soil leaching episodes that yield lys imeter waters. Equilibrium concentrations of Al reported in a range of Bs h orizons indicate that the allophanes present are less soluble than proto-im ogolite sols prepared in the laboratory and matured for up to 2 years.