Submitted to: Symposium on Application of Geophysics to Engineering and Environmental Problems Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 9, 2009
Publication Date: March 30, 2009
Citation: Sudduth, K.A., Kitchen, N.R., Myers, D.B., Drummond, S.T. 2009. Estimating Depth to Argillic Soil Horizons using Apparent Electrical Conductivity Response Functions. In: Proceedings of 22nd Symposium on Application of Geophysics to Engineering and Environmental Problems. p. 840-849 Technical Abstract: Maps of apparent electrical conductivity (ECa) of the soil profile are widely used in precision agriculture practice and research. A number of ECa sensors are commercially available, each with a unique response function (i.e., the relative contribution of soil at each depth to the integrated ECa reading). In past research we estimated depth to an argillic horizon (i.e., topsoil depth) on claypan soils by fitting empirical equations to ECa data from such sensors, either singly or in combination. The objective of this research was to take a more theoretical approach, estimating topsoil depth using a two-layer soil model incorporating multiple-sensor ECa data and published response functions. Data were obtained with sensors having five different ECa depth-response functions on two Missouri claypan-soil fields. Soil cores were also obtained in each field to provide calibration data. Using a numerical optimization approach, response-function calibration models were developed for each ECa dataset and for combination datasets. Accuracies of these different models were compared, and were also related to previous results from empirical equations. Accurate ECa-based estimations of topsoil depth will facilitate spatial investigation of soil hydraulic properties and crop production within claypan-soil fields.