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Removal of short‐range‐order minerals prior to grain‐size analysis of volcanic ash soils
Author(s) -
Velescu Andre,
Meßmer Tobias,
Scholten Thomas,
Kühn Peter
Publication year - 2010
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201000111
Subject(s) - dispersion (optics) , soil water , andosol , oxalic acid , mineralogy , allophane , oxalate , volcanic ash , weathering , chemistry , volcano , soil science , clay minerals , geology , geochemistry , inorganic chemistry , physics , optics
Incomplete dispersion of aggregates is a well‐known difficulty when analyzing soil texture of Andosols, particularly if no fresh soil material is available. To facilitate such investigations, several dispersion procedures were carried out on air‐dried samples rich in short‐range‐order minerals, originating from selected Andosol profiles (S Mexico). As a result, we propose an improved method based on a sequential chemical treatment with K oxalate, NH 4 oxalate, and oxalic acid that reliably removes cementing agents and allows for a stable dispersion of soil particles after addition of Na pyrophosphate. This method was proved to be well reproducible and highly reliable for routine grain‐size determinations. The potential error caused by the inherent risk of dissolving primary minerals or fresh volcanic glass remains far beyond the analytical error resulting from the incomplete and irreproducible dispersion of highly resistant aggregates by other commonly used techniques.