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Clay Mineralogy as Related to Morphology of Florida Soils with Sandy Epipedons
Author(s) -
Harris W. G.,
Carlisle V. W.,
Chesser S. L.
Publication year - 1987
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/sssaj1987.03615995005100060049x
Subject(s) - gibbsite , clay minerals , podzol , geology , silt , mineralogy , kaolinite , soil water , pedogenesis , ultisol , illite , gleysol , geochemistry , soil science , geomorphology
The clay mineralogy of Coastal Plain soils with sandy epipedons was studied with respect to taxonomic class, horizon, and the presence or absence of sand grain coatings. Relative estimates of claysized minerals were based on x‐ray diffraction peak height ratios after calibration with standards and normalization. Clay mineralogy of sandy horizons was related to whether the clay occurred as grain coatings or as loosely adhering floccules. Clays from coated (⩾5% silt + clay) and slightly coated (<5% silt + clay) sands were consistently high in hydroxy‐interlayered minerals (HIM), and usually contained gibbsite. Clays from floccules in the matrix of stripped (coating‐free) sands contained large amounts of quartz, variable smectite, little or no HIM, and no gibbsite. Mineralogical differences between clays associated with stripped sands vs. coated/slightly coated sands were highly significant statistically. Clay mineralogy of coated/slightly coated sandy horizons was similar regardless of taxonomic class or horizon depth. The A and E (stripped) horizons of Haplaquods were similar to stripped Quartzipsamment horizons in being depleted in HIM relative to other phyllosilicates. Haplaquod Bh and E′ horizons (coated to some degree) were relatively high in HIM and therefore were mineralogically similar to coated/ slightly coated Quartzipsamment horizons and to Arenic and Grossarenic Paleudult epipedons. Clay fractions from chemically reduced loamy horizons of Paleudults and Haplaquods were depleted in HIM relative to overlying coated sandy horizons. Results suggest that pedogenic processes that promote the destabilization of grain coatings (i.e., podzolization, chemical reduction) also promote the loss or redistribution of HIM associated with these coatings.