Non-invasive instrumentation opportunities for characterizing soil porous systems

Abstract Soil is widely recognized as one of the most complex systems present in the universe. It's highly non-linear and heterogeneous nature as well as the interacted and coupled physical, chemical and biological processes and phenomena occurring in the soil environment at different spatial and temporal scales are the main reasons for such complexity. As a consequence there is a need of appropriate methodologies and instrumentation to characterize soil porous systems either in the loaboratory or in the field. Moreover, the scientists and engineers face a great challenge to non-invasively measure and follow the changes occurring in soil systems caused by the human activities. Nevertheless, despite the enormous gap still to be bridged to better understand and manage in a sustainable way the new opportunities of soil resources for its characterization are nowadays available and should be exploited in soil science research. Those new opportunities are essentially interdisciplinary and are coming from other areas of knowledge such as space science, medicine, engineering and basic sciences. This paper will present examples and results and will present challenges and potentialities of new methods and instrumentation already available at different scales of observation. Spectroscopy, microscopy and high resolution imaging techniques including X- and gamma-ray and NMR tomography, atomic force microscopy and other recent tools will be shown. The characterization of macropores and preferential water flow infiltration in two and three dimensions were performed through the employment of commercial and dedicated scanners without disturbing the soil samples. The use of fractal geometry and a modified invasion percolation theory model were also employed to describe the “fingering” phenomena.