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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #207397

Title: Activation energies and temperature effects from electrical spectra of soil

item Logsdon, Sally

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2007
Publication Date: 3/19/2007
Citation: Logsdon, S.D. 2007. Activation energies and temperature effects from electrical spectra of soil [abstract]. Conference Proceeding Hawaii Soil Moisture Sensing Technology Conference: Current and Future Research Directions in Soil Mosture Sensing. p. 11.

Interpretive Summary:

Technical Abstract: Apparent permittivity often has soil-specific temperature responses as well as soil water responses. Variations of permittivity as a function of frequency and temperature can be used to calculate activation energies. The purpose of this study was to examine permittivity-temperature responses for six soils, and variation in calculated activation energies. Each of the six soils were packed into a truncated coaxial cell, and the permittivity spectra was determined for a range of water contents and temperartures. Then activations energies were calculated due to ion migration or due to rotation. The rotational activation energy was not correlated with temperature, did not vary across frequencies, and was not significantly affected by soil differences. Ion migration activation energy was significantly less for Cecil (kaolinite and quartz dominant mineralogy) than for Weld or Okoboji (smectites dominant mineralogy). There were significant positive temperature correlation for the dc electrical conductivity and for the real permittivity at low frequencies, but not at higher frequencies. Fraction of sorbed water had a significant correlation with electrical conductivity and real permittivity at a range of frequencies. Delineation of these temperature and activation energy responses is necessary for describing how various soils respond to electromagnetic measurements.