Fractal Geometry and Geostatistics for describing the Field Variability of Soil Aggregation

Fractal geometry has become a widely accepted descriptive tool for speci"c physical properties of natural soils and fractal scaling has recently been proposed as a model for soil particle size distribution. In this work, the cumulative mass distribution of dry soil aggregates, M(r(R), was estimated and shown to be proportional to R3D, where r is the aggregate size, R is a speci"c measuring scale and D is the fractal dimension, which is a measure of soil fragmentation: the larger its value, the greater the fragmentation. Aggregates were collected from a depth of up to 40 cm of a clay soil located at Metaponto (South Italy). The "eld of 23]25 m was sampled in 81 sites at the nodes of a semi-regular grid and aggregate size distribution was obtained by dry sieving the soil through a nest of sieves (sized 10, 5, 2, 1 and 0)5mm). The estimated D values were found to vary from 2 to 3 and were then interpolated by using the geostatistical procedure called ordinary kriging. The results were shown in the form of grey-coloured maps, which could be used as a useful tool for describing "eld variability in soil aggregation. ( 1999 Silsoe Research Institute