Field Calibration of Water Content Reflectometers
D. G. Chandlera,*,
M. Seyfriedb,
M. Murdockb and
J. P. McNamarac
a Dep. of Plants, Soils and Biometeorology, Utah State Univ., Logan, UT 84322-4820
b USDA-ARS, 800 Park Blvd, Boise, ID 83712
c Dep. of Geosciences, Boise State Univ., Boise, ID 83723

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Fig. 1. Overall linear regression and associated standard error values, as compared with the standard water content reflectometer (WCR) calibration curve and the manufacturer's specified range of error for P1 and P4.
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Fig. 2. Linear regression calibrations for individual water content reflectometer-time domain reflectometer (WCR-TDR) sensor pairs.
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Fig. 3. Comparison of soil moisture records in P3 and P4 at 15 and 30 cm, as represented by (a) the standard water content reflectometer (WCR) calibration and (b) individual in situ calibrations.
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Fig. 4. Comparison of application of standard water content reflectometer (WCR) calibration curves to time series WCR sensor output from (a) P1 and (b) P2 to application of individual linear calibration curves developed in situ at (c) P1 and (d) P2.
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Fig. 5. Upper and lower bounds to the ranges of error for the (a) factory calibrated and (b) in situ calibrated 15 and 65 cm water content reflectometer (WCR) response for the period May 1999 to April 2002.
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Copyright © 2004 by the Soil Science Society of America.