Genesis of loess-derived soils in southeastern Iowa

Abstract

Soil sampling 36 Morphological descriptions Laboratory Methods Physical properties Less than 2 AI clay Chemical properties Soil reaction Exchangeable cations "Free" iron Total organic carbon Total nitrogen Data from previous studies DISCUSSION OF RESULTS OF INVESTIGATIONS 49 Characteristics of the Soils (Grouped by Sequences) 49 Morphological characteristics 49 Laboratory data 58 ill Page Total nitrogen and organic carbon... 58 Exchangeable cation status 67 Less than 2 M clay 80 "Free" iron 91 DISCUSSION Biosequences Topo-Hyd.ro sequence s Geographic Location Sequences SUMMARY 147 LIST OF REFERENCES 152

Exchangeable aluminum and acidity in loess soils of south-central Iowa

“…The model form tested in the regional study in this in vestigation is a modified version of that presented by Corliss (1958) (Riecken, 1965). Blosser and Jenny (1971) illustrated the usefulness of this type of model by comparing the correlation between pH and base saturation from randomly selected soils and from soils selected to reflect trends in soil forming factors similar to the above model.…”

“…For instance, in thin loess the profile may be in deoxidized loess; in thick loess the profile may be entirely in oxidized loess. Many other influences may affect soil properties: time, parent material, underlying stratigraphy, and topography combine in a complex interaction; progressive increase of profile development occurs with the thinning of loess as a function of distance from sedi ment source (Hutton, 19^7;Ulrich, 1950;Ruhe, 1969); local loess sources probably modify soils in certain areas (Hunter, 1950); climatic influences may increase the amount of fine clay in the B horizon by textural development processes (Corliss, 1958 (Shrader, 1950). Corliss (1958) used this sequential biotic effect as his biosequence.…”

“…The regional model used in the present study is a modi fication of the model of Corliss (1958 (Protz, 1965;Tembhare, 1973 Cardoso (1957) Corliss (1955) Corliss (1958) Coultas (1951) Fenton (I966) Foth (1952); Foth and Riecken (195^) Green (1952)} Green andRiecken (1953) Hutton (1948; Hunter (1950) Hunter, Riecken, and McClelland (1953) (Black, 1968). This release from covalency to ionic bonding upon an increase in base results in a buffering effect and makes an end point arbitrary.…”

“…Drainage is one of the three state factors of the study model. Corliss (1958) had three drainage classes but not all of these have repre sentatives in some stages of development. In stages III and Iv, no well drained soils occur as mentioned earlier.…”

Relation of nonexchangeable potassium and magnesium to development in some Iowa soils

“…Bray (1937) states that physical weathering in the surface apparently breaks down the more easily broken beidellitetype materials containing no potassium and leaves the mica relatively more concentrated in the coarse colloidal fraction in the more weathered stages of soil development. Corliss (1958), Daniels (1956), Hanway et al (1960) and Ulrich (1951) studied exchangeable potassium, K"*", relationships in Iowa soils.…”