Parameters for describing soil macroporosity derived from staining patterns

Macroporosity influences the dynamics of water and dissolved solutes in the soil. Size, shape and continuity of macropores is affected by soil management. In this study, dye staining technique, followed by digital image processing, are used to quantify macroporosity under field conditions in a short time at low cost. We compared 17 macroporosity parameters, in 55 staining patterns from three fields with different soil management types at five depths, within one soil type. Factor analysis indicates that five factors explain 95% of the variation. The first factor equals the 'pore extent', and was similar for the three fields, but showed significantly lower values with increasing depths. The second factor is the 'individual pore size', and the third factor the 'shape' of the pores. Both were influenced by Soil management. Factors four and five were equal to the range and the nugget of the indicator variogram; respectively. We concluded that the most appropriate parameters to quantify staining patterns in an explanatory analysis are the number of pores, the average area per pore and the pore-shape, whereas the best parameter to quantify staining patterns with only one characteristic is the fractal dimension D-s. (C) 1998 Elsevier Science B.V.