EVALUATION OF SOIL AGGREGATE SURFACE ROUGHNESS BY IMAGE ANALYSIS

Aggregates measuring 7-10 mm sifted from four soils: Haplic Luvisol (silt), Rendzic Leptosol (clay loam), Rendzic Phaeozem (clay loam), and Gleyic Phaeozem (silty clay), were used to obtain aggregate structure models in the form of opaque polished blocks. By means of image analysis, the ratio of the perimeter to a minimum bounding ellipse perimeter of an aggregate cross-section was calculated to characterize the roughness of an aggregate surface. The mean value of the parameter ranged from 1.352 (LVha, smoother surface), 1.730 (PHgl, medium - rough surface), and 1.770 (LPrz, medium - rough surface) to 1.939 (PHrz, rougher surface) and was higher for the soils having larger quantity of sand sub-fraction (0.1-2 mm), clay fraction and soil organic matter.