Comparison of time domain reflectometry and the gravimetric method for the determination of soil water content

1991 ◽  
Vol 31 (1) ◽  
Author(s):  
SA Akrasi
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Gravimetric Method ◽  
Time Domain Reflectometry

CORRECTING SOIL VOLUMETRIC WATER CONTENTS FROM A DIRECT-READING TIME DOMAIN REFLECTOMETRY INSTRUMENT (IRAMS)

1989 ◽  
Vol 69 (3) ◽  
pp. 701-704 ◽  
Author(s):  
G. C. TOPP ◽  
J. L. B. CULLEY
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Computer Software ◽  
Time Domain Reflectometry ◽  
Direct Reading ◽  
Volumetric Soil Water Content ◽  
Linear Correction

Determination of volumetric soil water content (θ) using time domain reflectometry (TDR) is well established. A commercially available instrument (IRAMS) (the IRAMS (Instrument for Reflectometry Analysis of Moisture in Soils) is a trademark registered by Foundation Instruments Inc. of Ottawa) is now available which incorporates computer software, thus providing direct readouts of θ. A field study of the operation of the IRAMS showed that it operates consistently and repeatedly. The IRAMS values were higher but related linearly to those obtained using a TDR cable tester and manual calculations of travel times. A linear correction of the IRAMS readings is proposed and possible causes are suggested for the observed deviations from expected values. Key words: Time domain, reflectometry, soil water content, field

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 Sampling and TDR probe insertion in the determination of the volumetric soil water content

2003 ◽  
Vol 27 (4) ◽  
pp. 575-582 ◽  
Author(s):  
W. G. Teixeira ◽  
G. Schroth ◽  
J. D. Marques ◽  
Bernd Huwe
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Gravimetric Method ◽  
Time Domain Reflectometry ◽  
Volumetric Soil Water Content ◽  
Undisturbed Samples ◽  
Similar Accuracy ◽  
Volumetric Soil Water

Volumetric soil water content (theta) can be evaluated in the field by direct or indirect methods. Among the direct, the gravimetric method is regarded as highly reliable and thus often preferred. Its main disadvantages are that sampling and laboratory procedures are labor intensive, and that the method is destructive, which makes resampling of a same point impossible. Recently, the time domain reflectometry (TDR) technique has become a widely used indirect, non-destructive method to evaluate theta. In this study, evaluations of the apparent dielectric number of soils (epsilon) and samplings for the gravimetrical determination of the volumetric soil water content (thetaGrav) were carried out at four sites of a Xanthic Ferralsol in Manaus - Brazil. With the obtained epsilon values, theta was estimated using empirical equations (thetaTDR), and compared with thetaGrav derived from disturbed and undisturbed samples. The main objective of this study was the comparison of thetaTDR estimates of horizontally as well as vertically inserted probes with the thetaGrav values determined by disturbed and undisturbed samples. Results showed that thetaTDR estimates of vertically inserted probes and the average of horizontally measured layers were only slightly and insignificantly different. However, significant differences were found between the thetaTDR estimates of different equations and between disturbed and undisturbed samples in the thetaGrav determinations. The use of the theoretical Knight et al. model, which permits an evaluation of the soil volume assessed by TDR probes, is also discussed. It was concluded that the TDR technique, when properly calibrated, permits in situ, nondestructive measurements of q in Xanthic Ferralsols of similar accuracy as the gravimetric method.

Measuring Soil Water Content With Time Domain Reflectometry

Soil Science ◽  
2010 ◽  
Vol 175 (10) ◽  
pp. 469-473 ◽  
Author(s):  
Zhaoqiang Ju ◽  
Xiaona Liu ◽  
Tusheng Ren ◽  
Chunsheng Hu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Time Domain Reflectometry

scholarly journals Determination of soil water content using time domain reflectometer (TDR) for clayey soil

2018 ◽  
Author(s):  
N. H. H. Abdullah ◽  
N. W. Kuan ◽  
A. Ibrahim ◽  
B. N. Ismail ◽  
M. R. A. Majid ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Time Domain ◽  
Clayey Soil ◽  
Time Domain Reflectometer
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