Properties and Genesis of Finer Textured Subsoil Bands in Some Sandy Michigan Soils1
- E. Wurman,
- E. P. Whiteside and
- M. M. Mortland2
Field and laboratory studies show that the nonlimy, more reddish, finer textured layers (Bt) found in the subsoils of three coarse-textured soil profiles in Michigan contain a considerably higher concentration of silicate clay minerals and “free iron oxide” than the adjoining sandier layers. These layers also have slightly more organic matter than the adjoining sandier layers, and considerably less organic matter than the Bhir horizons in the same or associated profiles. These textural bands may or may not be from the same initial material as the horizons immediately above or below them. They are wholly or in part the result of pedogenetic processes.
Both physical and chemical mechanisms are probably involved in the textural band formation. The existence of complexes of “free iron oxide”-silicate clay-organic matter in the soil and their ability to move through artificial columns containing natural nonlimy soil material was demonstrated in the laboratory. In addition, the movement of silicate clay and iron-organic matter complexes simultaneously or at different times can be postulated. The deposition of the individual complexes or a combination of them may be caused by a chemical interaction between them, physical factors such as wetting and drying of the soil, or the activity of a third agency on one or both of the mobile constituents, e.g., free lime flocculating clay and/or organic-iron complexes. Results indicate that a combination of the above mentioned factors is needed to explain the physical, chemical, and micropedological observations.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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