Soil compaction imaging through Pedophysical Joint Inversion: a Northeastern Italy case study

 

One of the major threats to global arable lands is represented by soil compaction, mainly due to agricultural traffic. Modern heavy agricultural machinery and unsuitable soil moisture conditions might irreversibly induce soil compaction that, in turn, adversely affects soil quality and ecosystem. Restriction to root penetration alongside impaired water and air fluxes are a few principal drawbacks of compacted soils, resulting in significant ecological and economic damage to society.
However, traditional methods to study soil compaction are limited by punctual nature and not-in-situ conditions.
In this context, the purpose of this work was to combine different non-invasive geophysical techniques, with a joint inversion approach of the acquired datasets, to study the complexity of the soil structure. In detail, we tried to adapt the petrophysical joint inversion developed in permafrost systems, combining geoelectrical and seismic soundings to characterize the subsoil structure in compacted and non-compacted soils. This methodology rests on the conjunction of seismic refraction tomography (RST) and electrical resistivity tomography (ERT), acquired on the very line, through a representative pedophysical model, able to quantitatively estimate the fractions of investigated soil phases (e.g., air, water, and matrix fractions).
The survey was conducted on an arable field of “L. Toniolo” Padova University experimental farm. The reliability of the obtained models was compared with direct measurements of volumetric water content, bulk density, and penetration resistance along the survey line. Preliminary results showed that the methodology might be a promising tool for spatio-temporal evaluation of soil structure evolution as related to soil compaction.