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United States Department of Agriculture

Agricultural Research Service

Title: An Analysis of Aggregate Size Distribution Parameters

item Zobeck, Teddy
item Popham, Thomas
item Skidmore, Edward
item Merrill, Stephen
item Lindstrom, Michael
item Yoder, R - UNIV OF TN
item Lamb, J - UNIV OF MN

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2001
Publication Date: N/A

Technical Abstract: Since wind erosion is controlled, in part, by the amount of erodible material (<0.84mm) on the soil surface, estimates of surface soil dry aggregate size distributions (DASD) are needed to accurately estimate wind erosion. Surface samples of dry soil aggregates were collected for 2 to 4 years at 24 locations in 6 states. The soils represented a wide range of management systems and soil properties, including mineral and organic soils. The cropping systems included cotton, sorghum, wheat, soybeans, sugar beets, corn, potatoes, vegetables, and fallow conditions. The soils were sieved and DASD were expressed as log-normal (LN), Weibull (W) and fractal (F) distributions. Errors in aggregates size estimation varied with site and distribution tested. The LN distribution had the greatest estimation error and the W had the least error. The LN tended to over-estimate small aggregate sizes and under-estimate larger aggregates. The F over-estimated the small and large aggregates with the best estimate in the middle of the range. The W had no clear trends in estimate errors. We conclude the Weibull distribution produces the best estimates of aggregate sizes.

Last Modified: 4/22/2015
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