A Multifractal Approach for Assessing the Structural State of Tilled Soils
- Christian J. C. Roisin *
Although there are several methods for assessing the structural state of highly structured tilled soils, this task remains challenging because of the great heterogeneity of the solid phase caused by tillage tools and biological activity. This paper describes a method for quantifying the inner heterogeneity of elementary soil volumes large enough to be representative of the modifications caused by tillage implements. It is based on soil strength measurements collected at the intersection points of a 5 × 5 cm2 grid on the surface of an 80 × 80 cm2 area. This study shows that multifractal formalism is appropriate for analyzing the variability of such close measurements and could be a practical way of assessing the structural heterogeneity of agricultural soils. With this aim, two dimensionless parameters were defined to provide a characterization of the soil layers that captures field observations. The first one, Ir , called the regularity index, indicates the possible presence of strong irregularities caused by tillage implements while the second, Ih, called the homogeneity index, is related to the local variation of the structure. It expresses the structural homogeneity of soil layers not showing strong irregularity. The results produced from a series of 672 datasets highlight the good discriminating power of this last parameter. Due its high sensitivity to the spatial organization hidden in a dataset, it appears to be a better suited parameter to compare differently managed plots than the classical coefficient of variation (CV).Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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