GENESIS OF THE RYKER AND ASSOCIATED SOILS IN SOUTHERN INDIANA
Abstract
The Ryker soil, a Typic Paleudalf, occupies nearly-level, upland positions adjacent to the Ohio and Muscatatuck river valleys and their major tributaries. Away from the major valleys, landscapes of similar topographic character consist of Fragiudalfs and Fragiaqualfs of the Cincinnati catena. A soil geomorphic investigation of the southern edge of the Illinoian till plain in Jefferson County, Indiana, shows that in most areas the Ryker soil developed in loess-capped, loamy pedisediment derived from erosion of the Sangamon soil developed in the Illinoian till. In other areas the soil developed in loess-capped, shallow deposits of in-place Illinoian till. Where the unconsolidated deposits are thin, underlying lithology affects development of soils in this region. Where a fractured Silurian limestone underlies the loamy pedisediment or thin Illinoian till deposit, the Ryker soil, with no fragipan, formed. On the other hand, where slowly permeable shale bedrock or deeper glacial till and the associated paleosols underlie the pedisediment, the soils have fragipans. Iron oxides in these soils were characterized by an improved method of differential X-ray diffraction using an internal standard to adjust curve intensities before they are subtracted, and by measuring spectral absorption in the visible range. Spectral absorption has potential as a rapid, easy, very sensitive method for characterizing and measuring iron oxides in soils. The B2 horizons of the Ryker soil have redder hues and contain a greater proportion of goethite. Better drainage of the profile and increased time of weathering appear to be important factors favoring hematite formation.
Degree
Ph.D.
Subject Area
Agronomy
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