Premium
Extraction of Aluminum from Aluminum‐Organic Matter in Relation to Titratable Acidity
Author(s) -
Hargrove W. L.,
Thomas G. W.
Publication year - 1984
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/sssaj1984.03615995004800060052x
Subject(s) - titratable acid , chemistry , organic matter , lime , inorganic chemistry , muck , soil ph , aluminium , soil water , metallurgy , organic chemistry , geology , soil science , materials science , biochemistry
This study was conducted to further characterize aluminum (Al)‐organic matter complexes and their role in soil acidity. The objective was to determine the extractability of Al from organic matter and to relate it to titratable acidity. Two samples of muck were treated with Al 3+ in such a way as to achieve a range in Al saturation. The titratable acidity [determined conductimetrically with Ca(OH) 2 ] of selected samples was compared to the Al extracted with 1 M KCl, 0.5 M CuCl 2 , 2 M HCl, 1 M NH 4 OOCCH 3 (pH 4.8), 0.5 M CaCl 2 , and 0.33 M LaCl 3 . Results show that NH 4 OOCCH 3 (pH 4.8) is a very poor extractant of Al associated with organic matter. For unbuffered salts, the effectiveness of the extractant generally decreased as the valence of the replacing cation decreased (i.e. La 3+ > Ca 2+ > K + ). Copper is an exception to this rule as a result of its ionic structure and its tendency to form “inner sphere” complexes with organic matter, displacing a disproportionate fraction of the Al. Lanthanum extracts an amount of Al which seems well related to the titratable acidity and, thus, to the lime requirement. On the other hand, K + extracts far too little Al, while Cu 2+ extracts all of the Al present. The use of LaCl 3 to predict lime requirement on field soils (especially where organic matter is increasing such as for no‐tillage, etc.) looks promising but needs widespread evaluation.