Identification and Genesis of Fragipans in Ochrepts of North Central Wisconsin
- M. A. Habecker ,
- K. McSweeney and
- F. W. Madison
The morphological and physical properties of a fine-loamy, mixed, frigid Aquic Fragiochrept at two locations in Taylor County, Wisconsin were examined. At both sites, the fragic zone occurs in bisequal soils beneath eluvial horizons and transgresses a lithologic discontinuity where the loess cap grades into a dense sandy loam till. This study evaluated the utility of several field and laboratory tests for demarcation of the fragipan, and it examined the morphological and physical features of the fragipan in relation to its potential origin. Bulk density was measured using the saran-coated clod and Uhland ring methods. The upper boundary of the fragipan was distinguished from the overlying horizons by its higher bulk density with the Uhland ring method. Hydraulic conductivity (Ksat) of saturated soil was measured using two methods (falling-head permeameter and Guelph permeameter). Although Ksat values were low in the fragic zones (10−5.06–10−7.60 m s−1), they were not significantly lower than those measured in underlying nonfragic, dense till horizons. Soil strength tests showed that the site with >10% clay in its fragic horizons had twice the strength of the site with <10% clay. Various macro- and micromorphological features indicate that the upper part of the second parent material may be a debris flow sediment, rather than dense basal till and that the fragic zone may have been influenced by permafrost. This influence is seen by the presence of a suite of characteristics associated with permafrost such as vesicular porosity, platy structure, reverse sorting, and silt coatings superimposed on clay coatings or papules.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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