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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Soil Bulk Electrical Conductivity on Measuring Soil Water Content Using Time Domain Reflectometry

Authors
item Shen, F - IOWA STATE UNIVERSITY
item Swan, J B - IOWA STATE UNIVERSITY
item Jaynes, Dan
item Horton, R - IOWA STATE UNIVERSITY

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 22, 1998
Publication Date: N/A

Technical Abstract: Few studies have reported the effects of soil bulk electrical conductivity, EC, on time domain reflectometry, TDR, measured apparent soil dielectric constant, K. However, accurate measurement of K is necessary for accurate TDR estimates of soil water content, WC and solute concentration. In this study, the influence of EC on K was determined for packed cores over a range of EC of 0.07 to 1.47 dS/m and at five depths in an undisturbed soil core over a range of EC of 0.65 to 1.38 dS/m. For packed soil the semi-empirical relationship of K**1/2 to WC was significantly improved by adding EC**1/2 as an independent variable. The relation of K**1/2 to WC and EC**1/2 obtained from the packed soil measurements overestimated the effect of EC on K measurements for the undisturbed soil sore. A depth-specific linear relation of K and EC was required to remove the effect of bulk soil electrical conductivity on WC estimates for the undisturbed soil core.

Last Modified: 12/21/2014
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