Time Domain Reflectometry Laboratory Calibration in Travel Time, Bulk Electrical Conductivity, and Effective Frequency

2005 ◽  
Vol 4 (4) ◽  
pp. 1020-1029 ◽  
Author(s):  
Steven R. Evett ◽  
Judy A. Tolk ◽  
Terry A. Howell
Keyword(s):  
Electrical Conductivity ◽  
Travel Time ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Effective Frequency ◽  
Bulk Electrical Conductivity ◽  
Laboratory Calibration

Accuracy of Bulk Electrical Conductivity Measurements with Time Domain Reflectometry

2008 ◽  
Vol 7 (2) ◽  
pp. 426-433 ◽  
Author(s):  
J. A. Huisman ◽  
C. P. Lin ◽  
L. Weihermüller ◽  
H. Vereecken
Keyword(s):  
Electrical Conductivity ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Conductivity Measurements ◽  
Bulk Electrical Conductivity

scholarly journals TEOR DE POTÁSSIO NA SOLUÇÃO DO SOLO COM USO DA TÉCNICA DE REFLECTOMETRIA NO DOMÍNIO DO TEMPO

Irriga ◽  
2005 ◽  
Vol 10 (4) ◽  
pp. 409-418
Author(s):  
Tibério Santos Martins da Silva ◽  
Eugênio Ferreira Coelho ◽  
Vital Pedro da Silva Paz ◽  
Lucas Melo Vellame ◽  
Gessionei Da Silva Santana
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Solution ◽  
Time Domain ◽  
Potassium Concentration ◽  
Soil Disturbance ◽  
Time Domain Reflectometry ◽  
Ion Concentration ◽  
Bulk Electrical Conductivity ◽  
Water Sampler

TEOR DE POTÁSSIO NA SOLUÇÃO DO SOLO COM USO DA TÉCNICA DE REFLECTOMETRIA NO DOMÍNIO DO TEMPO  Tibério Santos Martins da Silva1; Eugênio Ferreira Coelho2; Vital Pedro da Silva Paz3; Lucas Melo Vellame1; Gessionei da Silva Santana41Universidade Federal da Bahia, Cruz das Almas, BA tibé[email protected] Mandioca e Fruticultura, Cruz das Almas, BA3Departamento de Engenharia Agrícola, Universidade Federal da Bahia, Cruz das Almas, BA4Universidade Federal de Viçosa, Viçosa, MG  1 RESUMO A avaliação do teor de íons no solo no manejo da fertirrigação é complexa devido a dificuldade de obtenção em tempo real e com o mínimo de alterações na estrutura do solo. Este trabalho teve como objetivo estimar o teor de potássio na solução do solo, a partir de modelos matemáticos ajustados, em função da condutividade elétrica da solução do solo (CEw) coletada por extrator de solução, da umidade (q) e da condutividade elétrica aparente do solo (CEa) obtidas por um equipamento de reflectometria no domínio do tempo (TDR). Os modelos estimaram razoavelmente a Cew e a reflectometria no domínio do tempo mostrou-se adequada para o monitoramento da concentração de potássio na solução do volume de solo molhado. UNITERMOS: TDR.  SILVA, T. S. M. da.; COELHO, E. F.; PAZ, V. P. da. S.; VELLAME, L. M.; SANTANA, G. da. S.; POTASSIUM CONCENTRATION IN SOIL SOLUTION USING TIME DOMAIN REFLECTOMETRY TECHNIQUE  2 ABSTRACT The evaluation of ion concentration in the soil under fertirrigation is complex due to the difficulty of obtaining it in real time, with a minimum of soil disturbance. This work aimed to estimate potassium concentration in soil solution as a function of soil solution electrical conductivity (CEw) collected by using water sampler, soil water content (q) and bulk electrical conductivity (CEa) obtained using a time domain reflectometry equipment (TDR). The models estimated reasonably CEw and time domain reflectometry was suitable for potassium concentration monitoring of wet soil volume solution. KEYWORDS: TDR. 

Evaluation of a Direct-Coupled Time-Domain Reflectometry for Determination of Soil Water Content and Bulk Electrical Conductivity

2016 ◽  
Vol 15 (1) ◽  
pp. vzj2015.08.0115 ◽  
Author(s):  
Robert C. Schwartz ◽  
Steven R. Evett ◽  
Scott K. Anderson ◽  
David J. Anderson
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Bulk Electrical Conductivity

scholarly journals CONDUTIVIDADE ELÉTRICA DA SOLUÇÃO DE SOLO EM FUNÇÃO DA CONDUTIVIDADE ELÉTRICA APARENTE E DA UMIDADE DO SOLO SOB APLICAÇÃO DE CLORETO DE POTÁSSIO COM USO DA REFLECTOMETRIA NO DOMINIO DO TEMPO

Irriga ◽  
2005 ◽  
Vol 10 (2) ◽  
pp. 174-183
Author(s):  
Tibério Santos Martins da Silva ◽  
Vital Pedro da Silva Paz ◽  
Eugênio Ferreira Coelho ◽  
Maurício Antônio Coelho Filho ◽  
Gessionei Da Silva Santana
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Solution ◽  
Time Domain ◽  
Linear Models ◽  
Time Domain Reflectometry ◽  
Soil Electrical Conductivity ◽  
Bulk Electrical Conductivity

CONDUTIVIDADE ELÉTRICA DA SOLUÇÃO DE SOLO EM FUNÇÃO DA CONDUTIVIDADE ELÉTRICA APARENTE E DA UMIDADE DO SOLO SOB APLICAÇÃO DE CLORETO DE POTÁSSIO COM USO DA REFLECTOMETRIA NO DOMINIO DO TEMPO  Tibério Santos Martins da Silva1; Vital Pedro da Silva Paz2; Eugênio Ferreira Coelho3; Maurício Antônio Coelho Filho3; Gessionei da Silva Santana41Universidade Federal da Bahia,  Cruz das Almas, BA, tibé[email protected] de Engenharia Agrícola, Universidade Federal da Bahia, Cruz das Almas-BA, 3Embrapa Mandioca e Fruticultura, Cruz das Almas-BA4Universidade Federal de Viçosa, Viçosa, MG,   1 RESUMO O trabalho teve como objetivo definir, em campo e em laboratório, modelos matemáticos que melhor relacionam a condutividade elétrica aparente (CEa), a umidade do solo (q) e a condutividade elétrica da solução do solo (CEw) sob aplicação de cloreto de potássio, via água de irrigação por gotejamento. O experimento consistiu de leituras de CEa e q com um analisador de umidade de reflectometria no domínio do tempo (TDR) em colunas de solo em laboratório e em várias posições de uma malha retangular de um perfil do solo, em condições de campo, seguido da extração de solução iônica nas respectivas posições. Foram ajustados modelos lineares e não lineares relacionando CEa, q e CEw. O resultados permitiram concluir que a CEw da solução do solo pode ser monitorada a partir de leituras de CEa pela TDR para fins de distribuição de solutos no solo sob fertirrigação, com uso dos modelos de Rhoades et al. (1976), Vogeler et al. (1996), Nadler et al. (1984) e empírico em condições de campo e laboratório. O modelo de Rhoades et al. (1989) e Rhoades et al. (1976) mostraram-se adequados apenas para os estudos em laboratório. UNITERMOS: fertirrigação, TDR  SILVA, T. S. M. DA; PAZ, V. P. DA S.; COELHO, E. F.; COELHO FILHO, M. A.; SANTANA, G. DA S. SOIL SOLUTION ELECTRICAL CONDUCTIVITY AS A FUNCTION OF BULK ELECTRICAL CONDUCTIVITY AND SOIL WATER CONTENT UNDER POTASSIUM CLORIDE APPLICATION USING TIME DOMAIN REFLECTOMETRY  2 ABSTRACT This study aimed to define mathematical models that suitably relate bulk electrical conductivity (CEa), soil water content (q) and soil solution electrical conductivity (CEw) under potassium chloride application by drip irrigation. The experiment consisted of readings of CEa and q using a Time Domain Reflectometry analyzer (TDR) in soil columns in laboratory and on several positions of rectangular soil profile grid under field conditions. Ionic solution was extracted in all positions of TDR readings. Linear and non-linear models relating CEa, q and CEw were adjusted to laboratory and field data. Results allowed to conclude that CEw may be monitored by readings of CEa from TDR for soil solute distribution under fertirrigation, using models of Rhoades et al. (1976), Vogeler et al. (1996), Nadler et al. (1984) and an empirical model in lab and in field. The models of de Rhoades et al. (1989) e Rhoades et al. (1976) were suitable only for laboratory studies. KEYWORDS: fertirrigation, soil electrical conductivity, TDR

A NEW METHOD TO MEASURE BULK ELECTRICAL CONDUCTIVITY IN SOILS WITH TIME DOMAIN REFLECTOMETRY

1990 ◽  
Vol 70 (3) ◽  
pp. 403-410 ◽  
Author(s):  
W. K. P. VAN LOON ◽  
E. PERFECT ◽  
P. H. GROENEVELT ◽  
B. D. KAY
Keyword(s):  
Electrical Conductivity ◽  
Transmission Lines ◽  
Time Domain ◽  
Correlation Coefficients ◽  
Time Domain Reflectometry ◽  
New Method ◽  
Measuring System ◽  
Reflection Measurement ◽  
Bulk Electrical Conductivity ◽  
Water Saturated

The bulk electrical conductivity of a porous medium can be determined by measuring the reflection of an electromagnetic pulse in transmission lines which are installed in this medium (the method is known as Time Domain Reflectometry (TDR)). The reflection is not only influenced by the medium, but also by the measuring system. A new method is described which corrects for influences of the measuring system by comparing a reflection measurement with a reference measurement performed in air. Calibration measurements were made in water and in water-saturated sand and loam soils. Columns with different, well-determined solute concentrations were prepared. Linear regression analyses were performed between the electrical conductivity determined with TDR and the electrical conductivity of the solutions. All slopes were close to one and the correlation coefficients were high: 0.993, 0.993 and 0.968 for water, sand and loam, respectively. For the two soils significant intercepts were found. These might be related to the surface charge of the soil particles. Key words: Dielectric constant, soil water, electrical conductivity, solutes

scholarly journals Technical Note:Practical considerations on the use of down-sized time-domain reflectometry (TDR) probes

2002 ◽  
Vol 6 (5) ◽  
pp. 949-955 ◽  
Author(s):  
M. A. Mojid
Keyword(s):  
Electrical Conductivity ◽  
Water Content ◽  
Travel Time ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry ◽  
Transition Time ◽  
Probe Length ◽  
Travel Path

Abstract. Nine time-domain reflectometry (TDR) probes, 2 to 10 cm long, were evaluated by comparing their measurement accuracy of TDR-pulse travel time in a sand and sandy loam soil, and electrical conductivity in NaCl solutions. TDR probes <2.5 cm in length generated trough-haped TDR waveforms with rounded corners at the points of the pulse reflection from the probe ends. The sharpness of the pulse reflection on the waveforms increased with both the increasing probe length and soil-water content. The transition time for the propagation of TDR pulse at the probe entrance increased as the soil dried up. The increased transition time caused a rightward movement of the first peak of the waveform at the probe entrance. Because of such peak movement, TDR-support software algorithm determined travel path of TDR pulse through the probe that was smaller than the actual travel path. TDR-measured pulse travel time tTDR varied erratically with the predicted pulse travel time tg (from volumetric soil-water content) for the probes <2.5 cm in length. But, for all probes ³2.5 cm in length, tTDR varied linearly with tg and followed the 1:1 line. TDR could not measure tTDR <300 ps accurately. A minimum probe length Lmin and the lowest allowable soil-water content qmin that the probe can accurately measure govern this lowest pulse travel time tmin. The mean absolute deviation between tTDR and tg was 77 ps for the 2.3 cm long probe and 1.39 ps for all probes ≥2.5 cm in length. All probes ≥2.5 cm in length measured electrical conductivity of salt solutions sTDR that compared well with the electrical conductivity measured by a conductivity meter sm. The length of the probes did not exert any noticeable influence on the accuracy of electrical conductivity measurement. Keywords: TDR probe, pulse travel time, dielectric constant, electrical conductivity

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