Evaluating the Linear Model of Dielectric Constant-Electrical Conductivity for Estimation of Soil Solution Electrical Conductivity with TDR

آب و خاک

Article 12, Volume 24, Issue 2, May 2010   

Document Type: Research Article

DOI: 10.22067/jsw.v0i0.3248

Authors

D. Namdar Khojasteh^{* 1}; M. Shorafa²; M. Fazeli Sangani¹

¹Dept. of Soil Science, University of Tehran

²University of Tehran

Abstract

Abstract
Time domain reflectometry (TDR) is a widely used method for measuring the dielectric constant (Ka) and bulk electrical conductivity (σa) in soils. The TDR-measured σa and Ka can be used to calculate the soil solution electrical conductivity, (σp). A theoretical model describing a linear relationship between bulk electrical conductivity, σa, and dielectric constant, Ka, in moist soil was already presented. By using this linear relationship, the pore water electrical conductivity, σp, can be estimated in a wide range of soil types without soil-specific calibration. The objective of this study was to evaluate the linear model presented previously for TDR. The previous study was on light texture soils but in this study we used clay, clay loam, loam, silty clay and silty clay loam textures. The results showed that the linear model performed well for light texture soils but not for heavy textures. Such poor result for heavy texture is mainly due to this fact that dielectric constant pore water was lower than 80 which was proposed as default by model. This study showed that for heavy texture soils dielectric constant of pore water is smaller than light textured soils.

Keywords: Time-domain Reflectometry, Electrical conductivity, Dielectric constant