Submitted to: Fast Times: News for the Near Surface Geophysical Sciences
Publication Type: Trade Journal
Publication Acceptance Date: 1/2/2018
Publication Date: 1/16/2018
Citation: Sudduth, K.A., Kitchen, N.R., Drummond, S.T. 2018. Estimating layered soil properties through inversion of apparent electrical conductivity data. Fast Times: News for the Near Surface Geophysical Sciences. 22(3):29-33.
Technical Abstract: Bulk apparent soil electrical conductivity (ECa) sensors respond to multiple soil properties, including clay content, water content, and salt content (i.e. salinity). Because they provide a single, weighted value for the soil profile it is generally difficult to elucidate strong relationships between ECa and the measured properties of individual soil layers. We investigated inversion of the equations that govern the ECa-depth response relationship to reconstruct layer soil conductivity using data collected in multiple fields. Layer conductivities obtained by inversion were first validated by comparison with ECa measured as a function of depth with a penetrometer. Then, the validated layer conductivities were related to laboratory- measured soil properties. Inversion worked well but sometimes required iterative adjustment of initial conditions and other input parameters to obtain best results. Strong linear relationships (r2 = 0.76) were obtained between inversion-estimated and measured layer conductivity data in all cases, sometimes with a truncated depth range. Layer conductivity data was able to estimate soil texture fractions in two fields examined, but not in a third, where there appeared to be parameters other than texture strongly affecting the EC response. Further examination of this approach is warranted to potentially provide improved ways to estimate depth-variable soil properties using ECa.