Quantification of soil macroporosity with image analysis**
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Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, P.O. Box 201, 20-290 Lublin 27, Poland
Int. Agrophys. 2004, 18(3): 217–223
Identification and description of the size and shape characteristics of irregular and branched macropores helps the evaluation of the transmission functions of soil. Such macropores are usually formed by tillage operations. In this paper we present a methodological approach, based on the Aphelion image analysis package, to the identification of macropores and quantification of their size and shape characteristics such as surface area, perimeter, circularity, minimum bounding rectangle fill (MBR-Fill) and compactness of resin impregnated opaque sections. This approach includes division of branched macropores into smaller pores if the bottlenecks between them are narrow, assuming that they act independently. Two approaches were used to quantify pore radius from pore surface area (geometrical radius) and from the ratio of pore surface and perimeter (hydraulic radius). The first approach gave more reasonable results, because the hydraulic radius seems to be often poorly sensitive to the pore surface area. Moreover, the pore radius was calculated from the perimeter and it was considerably lower than that determined from the pore surface area. However, taking into account some pore shape characteristics improves the correlation between both radii. The presented approach may help in predicting transmission functions of soil.