X-ray microtomography to characterize the physical properties of soil and particulate systems

Since many of the phenomena occurring in soil are related to grain and pore sizes and their distribution, investigation on a micrometric scale is of g reat importance. Also, the investigation should be non-invasive in order to avoid disturbing the region of interest of the sample. Many techniques fro m various areas of science have been adapted to make such investigations, b ut most of them are invasive or can only analyze global soil properties. Th us an X-ray tomograph was developed at Embrapa-Agricultural Instrumentation , to scan images of soil samples on a micrometric scale. A microtomographic image of a sieved soil sample, presenting aggregates from 212 mu m to 150 mu m and pores of 100 mu m, is shown. Pores of the same size can also be se en in a microtomograph of a sand column, composed of two layers with granul ometries of 106 mu m to 149 mu m and 297 mu m to 500 mu m. A microtomograph of a column composed of three layers of an orthoclasius powder is also pre sented. A slight variation in density along the column height can be observ ed. (C) 1999 Elsevier Science S.A. All rights reserved.