The determination of exchangeable cations in acid soils: Errors caused by weathering reactions during neutral salt extraction
Open Access
- 1 May 1991
- journal article
- Published by Canadian Science Publishing in Canadian Journal of Soil Science
- Vol. 71 (2) , 155-163
- https://doi.org/10.4141/cjss91-015
Abstract
To investigate pH-controlled chemical reactions associated with the neutral salt measurement of exchangeable cations in acid soils, and to estimate the potential error caused by such reactions, a series of experiments was performed which modify an established BaCl2 extraction method. Results showed that dissolution of amorphous silica, aluminum hydroxides and organic material occurs during neutral salt extraction, contributing cations to solution which are indistinguishable from exchangeable cations. As a result overestimates of exchangeable Al and Ca occur, but the error is not significant (> 10%) except in certain Ae horizons which are low in total CEC and high in exchangeable acidity. The 2-h BaCl2 method is recommended over the 4-hour NaCl method to minimize interference from weathering reactions. Key words: Cation exchange, exchangeable acidity, Al, H, acid forest soils, weatheringKeywords
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