Hydrodynamic characterization of soil compaction using integrated electrical resistivity and X‐ray computed tomography

Abstract

Modern agricultural practices can cause significant stress on soil, which ultimately has degrading effects, such as compaction. There is an urgent need for fast, noninvasive methods to characterize and monitor compaction and its impact on hydraulic processes. Electrical resistivity tomography (ERT) is a well-established method used for the assessment of soil hydraulic properties due to its high temporal resolution and sensitivity to changes in moisture content and salinity, whereas X-ray computed tomography (CT) can be used for high-spatial-resolution imaging of soil structure.We used the combined strengths of both methods to study soil under three different levels of compaction. The soils were X-ray scanned and electrically monitored after the application of a saline solution to the soil surface. The scans revealed the pore network architecture and allowed us to compute its size and connectivity. The ERT models revealed inhibited percolation rates for soils with a lower bulk density, but also how resistivity changes are spatiotemporally distributed within the soil columns. Furthermore, we obtained a quantitative link between the two methods, by which voxels more densely populated with pores were associated with higher temporal variations in electrical resistivity. Building on this, we established a spatial collocation between pore structure and distribution of solution during percolation. This demonstrates the potential of the combined strengths of the two tomographic methods to obtain an enhanced characterization of soil hydrodynamic properties.

Lasting Effects of Soil Compaction on Soil Water Regime Confirmed by Geoelectrical Monitoring

“…Assuming that differences in macroporosity are correctly inferred, this implies an increase of connectivity of soil aggregates as a result of soil compaction (see also Cimpoiasu et al., 2021). Such increases in aggregate connectivity for compacted soils are predicted when studying the dynamics of soil aggregate contacts in response to compaction controlled by soil rheology (see e.g., Or & Ghezzehei, 2002).…”

Geophysics conquering new territories: The rise of “agrogeophysics”

“…In their article "Toward high-resolution agronomic soil information and management zones delineated by groundbased electromagnetic induction and aerial drone data," von Hebel et al (2021) focus on the integration of soil EC a maps generated using a classical EMI survey with time-lapse aerial data to generate management zones at the size of agricultural machinery. They show that the information content in aerial data is highly time dependent and that for the analyzed case studies, no added value was observed when aerial data were added to the EMI data to delineate management zone.…”

“…In “Hydrodynamic characterization of soil compaction using integrated electrical resistivity and X‐ray tomography,” Cimpoiaşu et al. (2021) focus on the urgent need to develop fast techniques to characterize and monitor soil compaction. They used the combined capabilities of small‐scale X‐ray tomography and larger scale ERT tomograms to investigate the effect of different levels of compaction on soil hydrodynamic functioning.…”