Properties and genesis of loessial soils across a South-Central Nebraska basin
1993
Kuzila, M.S. | Lewis, D.T.
Each soil map unit on a detailed soil map represents soils in a landscape position. In Clay County, Nebraska, Crete silt loam (fine, montmorillonitic, mesic Pachic Argiustoll) was mapped both on upends surrounding breached basins and on basin floors. This was inconsistent with the expected pattern of soils in the basin landscape of the county. The objective of this study was to determine why this inconsistency existed. Four pedons were analyzed and 17 deep cores were examined along two transects across representative basins that were naturally drained. The present surface is the result of deposition of 2.5 to 8.0 m of loess on a paleobasin landscape dated 22 310 to 26 670 YBP. Field examination indicated slight differences in the morphology of the basin and upland pedons. Particle size and mineralogical data suggested the pedons formed in a combination of Peoria and Bignell loess units. Laboratory results indicated that the basin pedons should be classified as Vertic Paleustolls and Typic Argiustolls and the upland pedons should be classified as Vertic and Pachic Argiustolls. Crete soils formed both on the uplands and basin floors because the paleobasins formed prior to the deposition of the loess parent material; hence, the process of basin formation had little effect on the soils. The upland and basin sites had similar soil-forming conditions because the basins were naturally drained. Although landscape position appeared to have had a slight effect on classification of the pedons, the differences may be more related to distance from the source of the loess.
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