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Evaluation of the SoilVUE10 Time Domain Reflectometry for soil water measurements in testbed field conditions
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  • Timothy Wilson,
  • John Kochendorfer,
  • Howard Diamond,
  • Tilden Meyers,
  • Mark Hall,
  • Brent French,
  • Latoya Myles,
  • Rick Saylor
Timothy Wilson
NOAA

Corresponding Author:[email protected]

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John Kochendorfer
NOAA-ARL
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Howard Diamond
NOAA-ARL
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Tilden Meyers
NOAA-ARL
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Mark Hall
NOAA
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Brent French
NOAA
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Latoya Myles
NOAA-ARL
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Rick Saylor
NOAA-ARL
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Abstract

The U.S. Climate Reference Network (USCRN) has been engaged in ground-based soil water and soil temperature measurements since 2009. As a nationwide climate network, the network stations are distributed across vast complex terrains. Due to the expansive distribution of the network and the related variability in soil properties, obtaining site-specific calibrations for sensors is a significant and costly endeavor. Presented here are three commercial-grade electromagnetic sensors, with built-in thermistors to measure both soil water and soil temperature, including the SoilVUE10 Time Domain Reflectometry (TDR) probe (hereafter called SP, for SoilVUE Probe) (Campbell Scientific, Inc., Logan, UT), the 50 MHz coaxial impedance dielectric sensor (model HydraProbe (hereafter called HP), Stevens Water Monitoring Systems, Inc., Portland, OR), and the TDR-315L Acclima Probe (hereafter called AP) sensor (model TDR-315L, Acclima, Inc., Meridian, ID), which were evaluated in a nonconductive loam soil in Oak Ridge, Tennessee, USA from 2021 to 2022. The manufacturer-supplied calibration equation for loam soils was successfully used in this study. Measurements of volumetric water content by SP were much lower than gravimetric measurements in the top 20-cm soil horizon, where soil water showed relatively large spatial variability. Study results highlight that the SP may be an important alternative to reduce soil disturbances that usually ensue when HP and AP sensors are installed; however, in-situ calibrations are essential for the SP for xeric soil water conditions.