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

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

Contributions and future priorities for soil science: comparing perspectives from scientists and stakeholders

Soils are a fundamental natural resource but intensifying demands and increasing soil degradation necessitate focussed research into the sustainable use of soils. Since soil functioning is critical for the operations and performance of multiple industries, businesses and municipalities, soil scientists need to actively engage with these bodies to orientate research goals towards stakeholder needs. To achieve this, stakeholder views about the current and potential contributions of soil science to different sectors need to be taken into account when setting the future research agenda. Here, we assessed whether the current and future research priorities of soil science match the needs of four major industrial and environmental sectors: agriculture, ecosystem services and natural resources, waste management, and water management. We used an online questionnaire, distributed to 192 organisations and via social media, to compare stakeholders' and scientists' perceptions of (a) the contributions of soil science to date, (b) the areas not currently served by soil science and (c) future research needs in soil science. Stakeholders generally rated the contributions of soil science to date as ‘great’ or ‘fundamental’, but scientists rated the contributions more highly. Respondents identified numerous areas that soil research has not yet sufficiently addressed, which were mostly sector-specific and often overlapped with perceived future research needs. Importantly, stakeholders' and scientists' views of future research priorities differed strongly within sectors, with the notable exception of agriculture, where views were generally consistent. We conclude that soil science may hold unexplored potential in several industrial and environmental sectors. We call for improved research communication and greater stakeholder involvement to shape the future soils research agenda and ensure the sustainable use of soils across multiple areas of society

Characterization of a Deglaciated Sediment Chronosequence in the High Arctic Using Near‐Surface Geoelectrical Monitoring Methods

Accelerated climate warming is causing significant reductions in the volume of Arctic glaciers, such that previously ice-capped bare ground is uncovered, harboring soil development. Monitoring the thermal and hydrologic characteristics of soils, which strongly affect microbial activity, is important to understand the evolution of emerging terrestrial landscapes. We instrumented two sites on the forefield of a retreating Svalbard glacier, representing sediment ages of approximately 5 and 60 years since exposure. Our instrumentation included an ERT array complemented by adjacent point sensor measurements of subsurface temperature and water content. Sediments were sampled at each location and at two more additional sites (120 and 2000 years old) along a chronosequence aligned with the direction of glacial retreat. Analysis suggests older sediments have a lower bulk density and contain fewer large minerals, which we interpret to be indicative of sediment reworking over time. Two months of monitoring data recorded during summer 2021 indicate that the 60-year-old sediments are stratified showing more spatially consistent changes in electrical resistivity, whereas the younger sediments show a more irregular structure, with consequences on heat and moisture conductibility. Furthermore, our sensors reveal that young sediments have a higher moisture content, but a lower moisture content variability