ABSTRACT:
Electromagnetic induction (EMI) is a relatively low cost and rapid method for measuring and mapping soil salinity over broad areas. This study compares apparent conductivity (ECa) data obtained with single-frequency (EM38 meter) and multi-frequency (GEM300 sensor) EMI instruments and relates apparent conductivity measured by these instruments with the more conventional conductivity of saturated extract (ECe). Correlation coefficients between the ECa data sets obtained with the two instruments were 0.80 and 0.86 in the horizontal and vertical dipole orientations, respectively. Although the GEM300 sensor produced higher apparent conductivity measurements and also predicted somewhat less accurately the conductivity of soil samples, spatial pattern of apparent and electrical conductivity produced by the two instruments were similar and reasonable. Multi-frequency sounding with the easier-to-operate GEM300 sensor was found to provide no additional information and did not improve interpretations over single frequency sounding.
Footnotes
Jim Doolittle is a research soil scientist with the U.S. Department of Agriculture, Natural Resources Conservation Service in Newtown Spare, Pennsylvania. Michael Petersen is an area resource soil scientist with the U.S. Department of Agriculture, Natural Resources Conservation Service in Greek, Colorado, and Tim Wheeler is a soil scientist (TSS) with the U.S. Department of Agriculture, Natural Resources Conservation Service in Lakewood, Colorado.
- Copyright 2001 by the Soil and Water Conservation Society
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