Distribution of Concretions from Selected Soils of the Inner Bluegrass Region of Kentucky
1972
Phillippe, W. R. | Blevins, R. L. | Barnhisel, R. I. | Bailey, H. H.
Total iron and manganese was determined on concretions and soil samples by X-ray emission. Soils studied included Maury, Mercer, and Lawrence, which are well-drained, moderately well-drained and somewhat poorly-drained, respectively. Iron-Manganese concretions were observed in all horizons, with a maximum of 46% by weight in a Maury C horizon. The Fe/Mn ratios decreased with increasing concretion size. This decrease was largely due to increased Mn content associated with the larger size concretions. Further analyses for composition showed that quartz and clay minerals (vermiculite, montmorillonite, kaolinite, and mica) account for most of the remaining fractions. Traces of titanium and phosphorus were also found. Microscopic studies of the concretions indicated two types of internal fabric; (i) undifferentiated (structureless), and (ii) differentiated or concentric structure. Concretions from the somewhat poorly drained soils are characterized by undifferentiated fabric and diffuse external boundaries. In contrast the concretions from the well-drained soils are usually spherical, with sharp external boundaries and differentiated fabric.
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