Pore networks in an Italian Vertisol: Quantitative characterisation by two dimensional image analysis

Image analysis of photographs made from 5 cm x 10 cm soil thin sections from a Vertisol profile (0-175 cm depth) in southern Italy demonstrates the existence of two types of pore networks: a network of pores of continuously decreasing porosity and irregularly abundant macropores. These pore networks change in a regular manner from one depth to another. Certain macropores occur in the range of the network of continuously decreasing abundance but their anomalous abundance sets them apart from the other pores. This macropore network varies in porosity in an irregular manner from one depth to another in the profile. The soil profile samples studied can be divided into three zones, self mulching surface, 10-80 cm, that of agricultural activity, and 90-175 cm, below this activity, The continuously varying smaller pore network is of low and rather constant porosity in the upper part of the profile but it has its highest porosity at 95 cm decreasing regularly as a function of depth below this level. Macropore networks decrease in prorsity with depth also but in an irregular manner, The numerical characterisation of soil pore networks gives a much better idea of the type and abundance of pores which should lead to a better understanding of permeability and transport characteristics in soil.