Twenty-five years of computed tomography in soil physics: A literature review of the Brazilian contribution

The last 25 years of the use of computed tomography in Brazil, applied to soil physics is here presented. This period ranges from the first publication made by Brazilian researchers in 1985 to 2010. Discussion is made on the use of 1st to 3rd generation tomographic systems, with millimetric and micrometric resolutions, using X and gamma-ray, and neutron sources. The main achievements of these researchers involve studies on soil compaction, surface soil sealing, effects of wetting-drying cycles on soil structure, soil porosity and pore size distribution, water movement through soils and effects of agricultural management systems on soil structure. Therefore, the results presented in this review have the aim of giving to the reader the state of art of the Brazilian research using tomographic systems.

Research highlights▶ The main applications of CT in soil physics in Brazil involve studies of the distribution of bulk density and water content, changes in porosity, natural and artificial changes in soil structure, soil water movement, soil sample quality, and effect of different management practices on soil structure. ▶ The use of CT allows quick non-invasive measurements of soil water content in 2D and 3D analyses of samples of any shape. ▶ The broadening of the use of the 3rd generation X-ray microtomography enhanced by Brazilian institutes and universities that work in soil science would certainly lead to new applications of CT that would bring new developments related to soil structure, like more realistic studies on tortuosity, connectivity, shape, size and pore distribution. ▶ New tomographic models based on the use of radiation from synchrotron light, positrons and neutrons may become interesting alternatives for the study of soil physical characteristics, opening the possibility of obtaining images of greater resolution and also presenting a greater sensitivity to monitor soil water content changes.