The distribution of selected soil properties in a first-order loess watershed

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1984
Authors
Wysocki, Douglas
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Agronomy

The Department of Agronomy seeks to teach the study of the farm-field, its crops, and its science and management. It originally consisted of three sub-departments to do this: Soils, Farm-Crops, and Agricultural Engineering (which became its own department in 1907). Today, the department teaches crop sciences and breeding, soil sciences, meteorology, agroecology, and biotechnology.

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The Department of Agronomy was formed in 1902. From 1917 to 1935 it was known as the Department of Farm Crops and Soils.

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1902–present

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  • Department of Farm Crops and Soils (1917–1935)

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Agronomy
Abstract

Accelerated erosion poses several problems for soil classification. Removal of surface soil can result in the thinning or removal of a mollic epipedon and can alter the clay distribution, an essential feature, of an argillic horizon. Erosional processes and soil properties vary across the landscape. This study examines the distribution of clay, total phosphorus, organic carbon, pH, clay mineralogy, and soil micromorphology in a small, first-order loess watershed. Twenty pedons from five different hillslope elements were used to study the relationship between soil properties, landscape position, and erosion;Soils on the summit and shoulder positions are similar in their clay, total phosphorus, organic carbon, and pH distributions. Shoulder soils are slightly more eroded than soils on the summit. Clay distributions on both positions are marginal to the argillic requirement. Thin section analysis, however, shows sufficient illuvial clay to meet the argillic criteria. Total phosphorus distributions resemble curves for forest or transition soils. Summit and shoulder soils are best classified as eroded Alfisols;Backslope soils display little profile development. Clay maximums and total phosphorus minimums occur at the surface. Illuvial clay is not evident in thin section. Accelerated erosion has truncated at significant portion of these soils. Evidence suggests that soils on the backslope were Inceptisols prior to cultivation;Footslope soils are a result of cumulic additions. A well-defined zone of phosphorus depletion exists in these soils. The organic carbon content in the footslope soils varies with aspect within the watershed. These soils are Mollisols;Toeslope soils are composed predominantly of post-cultural erosion sediments and inherit their properties from this material. Lighter colored sediments at the soil surface place these soils in the Entisol order;Clay mineralogy is consistent between landscape positions. Smectite content increases with depth while hydroxy interlayer minerals have a maximum in the surface and decrease with depth. Minor amounts of kaolinite, quartz, and vermiculite make up the remainder of the clay suite. Soils on younger geomorphic surfaces contain more vermiculite in the lower horizons. Smectites at all positions appear to have a mix of both tetrahedral and octahedral charge.

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Sun Jan 01 00:00:00 UTC 1984