| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Soil Science Dep.
USDA-ARS, 1991 Upper Buford Circle, Univ. of Minnesota, St. Paul, MN 55108
*Corresponding author.
ABSTRACT
Time domain reflectometry (TDR) is used for the simultaneous determination of soil moisture content and electrical conductivity (EC). Limitations of parallel probes compared with coaxial probes have been signal losses in the antenna wire leading to the probes, and the required use of an expensive balun. In addition, signal attenuation in the balun hampered accurate EC determination. We describe a balun that avoids these limitations. It is a 1:1 balun, which means that it converts the electrical field from unbalanced to balanced, but no impedance transformation takes place. Consequently, this balun does not attenuate low-frequency signals, which is inherent to commonly used commerical 1:4 baluns. The balun is inexpensive and easy to fabricate, and is attached directly to a parallel pair of waveguides. This permits a system with coaxial transmission line from the TDR to the parallel waveguides. For soil moisture content determinations, the new balun performs at least as well as a conventional balun. Furthermore, EC of NaCl solutions determined from the TDR trace showed excellent agreement with EC measured with a conductance meter.
Received for publication June 3, 1992.
This article has been cited by other articles:
|
|
 |
|
  P. Castiglione, P. J. Shouse, and J. M. Wraith Multiplexer-Induced Interference on TDR Measurements of Electrical Conductivity Soil Sci. Soc. Am. J., August 3, 2006; 70(5): 1453 - 1458. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. D. Logsdon Experimental Limitations of Time Domain Reflectometry Hardware for Dispersive Soils Soil Sci. Soc. Am. J., February 27, 2006; 70(2): 537 - 540. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Logsdon Time Domain Reflectometry Range of Accuracy for High Surface Area Soils Vadose Zone J., November 11, 2005; 4(4): 1011 - 1019. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. A. Robinson, D. A. Robinson, S. B. Jones, J. M. Wraith, D. Or, and S. P. Friedman A Review of Advances in Dielectric and Electrical Conductivity Measurement in Soils Using Time Domain Reflectometry Vadose Zone J., November 1, 2003; 2(4): 444 - 475. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. L. Corwin and S. M. Lesch Application of Soil Electrical Conductivity to Precision Agriculture: Theory, Principles, and Guidelines Agron. J., May 1, 2003; 95(3): 455 - 471. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Castiglione and P. J. Shouse The Effect of Ohmic Cable Losses on Time-Domain Reflectometry Measurements of Electrical Conductivity Soil Sci. Soc. Am. J., March 1, 2003; 67(2): 414 - 424. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Amente, J. M. Baker, and C. F. Reece Estimation of Soil Solution Electrical Conductivity from Bulk Soil Electrical Conductivity in Sandy Soils Soil Sci. Soc. Am. J., November 1, 2000; 64(6): 1931 - 1939. [Abstract] [Full Text]
|
|
|
|
|
|
G.C. Topp, S. Zegelin, and I. White Impacts of the Real and Imaginary Components of Relative Permittivity on Time Domain Reflectometry Measurements in Soils Soil Sci. Soc. Am. J., July 1, 2000; 64(4): 1244 - 1252. [Abstract] [Full Text]
|
|
|
|
|
|
S.D. Logsdon Effect of Cable Length on Time Domain Reflectometry Calibration for High Surface Area Soils Soil Sci. Soc. Am. J., January 1, 2000; 64(1): 54 - 61. [Abstract] [Full Text]
|
|
|
|
|
|
M.D. Tomer, B.E. Clothier, I. Vogeler, and S. Green A Dielectric-Water Content Relationship for Sandy Volcanic Soils in New Zealand Soil Sci. Soc. Am. J., July 1, 1999; 63(4): 777 - 781. [Abstract] [Full Text]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Agronomy Journal | Crop Science | |||
| Journal of Natural Resources and Life Sciences Education |
Vadose Zone Journal | ||||
| Journal of Plant Registrations | Journal of Environmental Quality |
The Plant Genome | |||
