A well-developed soil structure is a key attribute of a productive and functioning soil. Evidence shows that subtle changes in the spatial arrangement and binding of soil constituents impart large changes in soil mechanical and hydraulic properties and associated ecological services. However, these features remain difficult to quantify at spatial scales relevant for agricultural management. In this work, we propose a pedophysical model to interpret macroscopic seismic properties in terms of soil structure. The model captures subtle soil mechanical traits accounting for soil plastic deformation due to compaction. In order to evaluate the model, we use data from field monitoring at an experimental site that revealed elevated seismic velocities in plots that were compacted 5 yr prior to our measurements. Our results show that P-wave velocities carry a strong imprint of soil compaction and are well predicted by the proposed model. The model infers contact areas between aggregates that are nearly threefold larger for compacted than for non-compacted soils, indicating that soils have not recovered from compaction. The study illustrates the potential of seismic methods to identify chronic compaction at field scale.
