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United States Department of Agriculture

Agricultural Research Service

Title: Scaling in Soil Aggregate Distribution As Dependent on Aggregate Water Content and Soil Compaction

Authors
item Pachepsky, Yakov
item Guber, Andrey - MOSCOW UNIVERSITY

Submitted to: Joint Assembly of the European and American Geophysical Unions
Publication Type: Proceedings
Publication Acceptance Date: February 5, 2003
Publication Date: April 6, 2003
Citation: Pachepsky, Y.A., Guber, A. 2003. Scaling in soil aggregate distribution as dependent on aggregate water content and soil compaction. Joint Assembly of the European and American Geophysical Unions, April 6-10,2003, Nice,France. CDROM.

Technical Abstract: Fractal scaling has been documented in literature for mass of dry soil aggregates. Changes in water content are known to cause shrinking or swelling in aggregates. The objective of this work was to determine (a) whether the fractal scaling will hold for aggregates at various water contents, (b) how does mass fractal dimension depend on water content if the fractal scaling holds, (c) how will soil compaction affect the scaling. Soil samples were taken from several depths of Gray Forest soil for four different levels of compaction caused by agricultural machinery passes. The aggregate bulk density was measured with the kerosene method in air-dry aggregates, at saturation, and at two intermediate water contents. The power-law scaling mass=A*(diameter)^D was applicable to aggregates from all depths in the studied water content range. Bulk density at saturation did not depend on aggregate size, and D was equal to three for all aggregate sizes studied. Both the parameter A and the mass fractal dimension D depended on water content, and the dependencies could be approximated well with linear functions. Coefficients of those linear functions reflected aggregate size and were sensitive to the degree of compaction. The observed scaling provides a succinct representation of complex structure by a small number of parameters that can be used as complements to other soil parameters to show effects of soil management on soil structure.

Last Modified: 10/25/2014