Campus Units

Agronomy

Document Type

Article

Publication Version

Published Version

Publication Date

2014

Journal or Book Title

Soil Science Society of America Journal

Volume

78

Issue

5

First Page

1500

Last Page

1506

DOI

10.2136/sssaj2013.10.0429

Abstract

Frequency domain reflectometry (FDR) is an inexpensive and attractive methodology for repeated measurements of soil water content (θ). Although there are some known measurement limitations for dry soil and sand, a fixed-frequency method is commonly used with commercially available FDR probes. The purpose of our study was to determine if the soil dielectric spectrum could be used to measure changes in θ. A multifrequency FDR probe was constructed with a 6-mm diameter, and a soil dielectric spectrum was obtained. Using the dielectric spectrum, the dielectric dispersion frequency (fd) was determined. It was discovered that changes in fd were highly correlated with changes in θ, and a third-order polynomial equation (R2 = 0.96) was developed describing the relationship. The effectiveness of fd for θ measurement was evaluated for three soils and a sand across a range of θ. The effects of soil temperature and soil salinity were also evaluated. Accurate measurements of θ were obtained even in dry soil and sand. The root mean square error of the θ estimated by the fdmeasurement was 0.021. The soil temperature and soil salinity had no measureable effects on θ determination. The use of fd for θ determination should be an effective and accurate methodology, especially when dry soils, soil temperature, and/or soil salinity could potentially cause problems with the θ measurements.

Comments

This article is published as Xu, Jinghui, Sally D. Logsdon, Xiaoyi Ma, Robert Horton, Wenting Han, and Ying Zhao. "Measurement of Soil Water Content with Dielectric Dispersion Frequency." Soil Science Society of America Journal 78, no. 5 (2014): 1500-1506. doi: 10.2136/sssaj2013.10.0429. Posted with permission.

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Language

en

File Format

application/pdf

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