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United States Department of Agriculture

Agricultural Research Service

Title: Wind Erodibility of Organic Soils

Authors
item Kohake, David
item Skidmore, Edward
item Hagen, Lawrence

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2009
Publication Date: January 1, 2010
Repository URL: http://soil.scijournals.org/cgi/reprint/74/1/250
Citation: Kohake, D.J., Skidmore, E.L., Hagen, L.J. 2010. Wind erodibility of organis soils. Soil Science Society of America Journal. 74:250-257.

Interpretive Summary: Numerous soil properties were found for organic soils to determine their wind erodibility. The data should prove useful to improve the predictive abilities of physically-based wind erosion models. The organic soils had much lower aggregate densities compared to mineral soils. The DAS showed that these soils have medium to high stabilities. ASD varied for the soils used in the study and had a significant effect on U*t and soil loss amounts. U*t for the organic soils were slightly higher than would be predicted for mineral soils with the same ASD. Soil loss amounts showed a wind of a given strength should erode equal weights of soil from organic and mineral soils. Amounts would be higher when looking at volumes of soil eroded due to organic soils having lower densities. AAC revealed that aggregates of organic soils should be moderately resistant to abrasion. This coincides with the aggregates having medium to high stabilities. CAC were higher than the AAC, meaning a crusted soil surface should be easier to abrade than a well aggregated soil. LEM amounts were similar to amounts for mineral soils, and seems to be a function of soil texture as well.

Technical Abstract: Intensively cropped organic soils are often subject to severe wind erosion. However, their erodibility parameters for use in physically-based erosion prediction models are generally lacking. The objective of this study was to measure the properties of selected organic soils that affect their wind erodibility. Four organic soils were collected from Florida, North Carolina, and Michigan. The organic matter content, aggregate density, dry aggregate stability (DAS), aggregate size distribution (ASD), and soil water characteristics were measured. Trays (122 x 20 x 6 cm) were filled with field sampled soils and soils with 80 percent of aggregates less than 0.84 mm. The soil filled trays were placed in the floor of a laboratory wind tunnel and exposed to wind of various speeds. Threshold friction velocities (U*t), soil loss, aggregate (AAC) and crust abrasion coefficients (CAC),and loose erodible material (LEM) were measured. Aggregate densities ranged from 0.93 to 1.13 Mg m-3, which is lower than typical mineral soils. Dry aggregate stability was moderately high to high (2.9 - 4.7 ln(J kg-1)). Threshold friction velocity varied from 0.40 to 0.83 m s-1 for the field condition and 0.27 to 0.31 m s-1 for the soil with 80% of the aggregates less than 0.84 mm. AAC ranged from 0.0006 to 0.0136 m-1, meaning the aggregates should be moderately resistant to abrasion losses. CAC varied from 0.039 to 0.123 m-1, so a crusted soil surface should abrade easier than a well-aggregated soil. LEM ranged from 0.010 to 0.068 kg m-2 and seemed dependent on the texture of the mineral component. The threshold friction velocities of organic soils were slightly higher than would be predicted for comparable mineral soils. However, from the results of this study it is expected that for a given wind speed, near equal mass of soil would be eroded from organic soils as from comparable mineral soil.

Last Modified: 10/25/2014
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