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United States Department of Agriculture

Agricultural Research Service

Title: Fractal Analysis of Aggregate Size Distribution: the Question of Self Similarity

Authors
item Logsdon, Sally
item Gimenez, D - UNIVERSITY OF MINNESOTA
item Allmaras, Raymond

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 1996
Publication Date: N/A

Interpretive Summary: Rapid movement of agricultural chemicals through soil may occur because the soil is not uniform. Instead, the soil is clumped with spaces between the clumps. Water and chemicals may move rapidly through the spaces between soil clumps. The spaces between clumps are difficult to describe. So often the soil clumps themselves are measured as a distribution of soil clumps of different sizes. Sometimes this distribution is described by one number, a fractal dimension, which may be used to indirectly calculate the amount of space between soil clumps. This study showed that the different sizes of soil clumps did not have similar properties, and could not be described by a fractal dimension. Studying sizes of soil clumps would not help understand the rapid movement of agricultural chemicals through the soil.

Technical Abstract: Aggregate distributions are often described as fractal, with assumed scale-invariant aggregate density, shape, and relative diameter (diameter as a fraction of the smallest diameter of the sieved class). The objective of this study was to test the assumptions of scale-invariant density, shape, and relative diameter. Numbers of aggregates were counted for each sieved-class of two data sets. This information was used to back calculate aggregate density and relative diameter for each sieved-class. Aggregate density, shape, and relative diameter could not all have been scale-invariant, but at least two of the three factors could have been scale-invariant across a limited range of sieve-class sizes.

Last Modified: 8/31/2014
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