|Sudduth, Kenneth - Ken|
|Sadler, Edward - John|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 1/30/2009
Publication Date: 8/5/2010
Citation: Myers, D.B., Kitchen, N.R., Sudduth, K.A., Grunwald, S., Miles, R.J., Sadler, E.J., Udawatta, R. 2010. Combining Proximal and Penetrating Soil Electrical Conductivity Sensors for High Resolution Digital Soil Mapping. In: Viscarra Rossel, R. A., McBratney, Alex B., and Minasny, B. Proximal Soil Sensing, Volume 1. New York: Springer. p. 233-243. Interpretive Summary:
Technical Abstract: Proximal ground conductivity sensors produce high spatial resolution maps that integrate the bulk electrical conductivity (ECa) of the soil profile. Variability in conductivity maps must either be inverted to profile conductivity, or be directly calibrated to profile properties for meaningful interpretation. Penetrating apparent electrical conductivity (ECp) sensors produce high depth resolution data at relatively fewer spatial locations. The objectives of this research are to (i) investigate the profile source of ECa in claypan soils via a detailed examination of ECp profiles, (ii) examine the potential for feature detection with ECp in claypan soils, and (iii) determine if ECa sensors can be calibrated to ECp features. Two study areas were chosen representing the claypan soils of northeast Missouri, USA. Profile conductivity was measured at high depth resolution on soil cores using a miniaturized Wenner conductivity probe and in the field using a conductivity penetrometer. Proximal ground conductivity was mapped with one direct contact sensor and two non-contact sensors providing 5 distinct coil/electrode geometries. Increasing ECp was observed below the claypan correlating with decreasing clay and water content and increasing bulk density. Depth to the claypan was successfully calibrated to derivative peaks on ECp profiles (r^2 0.72, p<0.001). Relationships between ECa and ECp features were poor (r^2 ~0.21) to good (r^2~0.87) on a field specific basis. Results show that ECp can be used for calibration of ECa to the depth to claypan.