4D X-Ray Computed Tomography in Soil Science: an Overview and Future Perspectives at Mogno/Sirius

X-ray computed tomography (XCT) is a well-established technique to characterize the 3D spatial arrangement of soil structure. However, 4D XCT (3D + time) has been demonstrated to be an essential step into new insights on dynamic processes occurring in the soil (e.g., fluid flow, plant root development, hydro-mechanical behavior). With the recent advances in X-ray sources such as fourth-generation synchrotron light sources, the temporal resolution of 4D XCT experiments has increased to the order of seconds. Therefore, this paper seeks to describe the current state of the art regarding 4D XCT applied in two hot topics in soil science: (i) fluid flow and water distribution and (ii) soil-root interactions. In addition, future perspectives involving the XCT beamline (Mogno) at the new Brazilian synchrotron facility (Sirius) are presented aiming to enlighten possibilities of innovative 4D XCT investigations in soil science. The main capabilities of this beamline that will be linked with currently identified soil-related research limitations and gaps are increased spatial and temporal resolutions, multiscale analysis, high energy, and phase contrast imaging.