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This article in SSSAJ

  1. Vol. 57 No. 4, p. 930-934
    Received: Oct 8, 1992

    * Corresponding author(s):
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Test of a Heat-Pulse Probe for Measuring Changes in Soil Water Content

  1. Keith L. Bristow ,
  2. Gaylon S. Campbell and
  3. Kees Calissendorff
  1. CSIRO Division of Soils, Private Mail Bag, P.O. Aitkenvale, Townsville, QLD 4814, Australia
    Dep. of Agronomy and Soils, Washington State Univ., Pullman, WA 99164
    Soiltronics, 1111 Myrtle Drive, Burlington, WA 98233



The maximum temperature rise measured at some distance from a line heat source can be used to determine the volumetric heat capacity and hence water content of porous media. We describe a simple heat-pulse device for determining the volumetric heat capacity and hence water content of porous media. The device consists of three needle probes (0.813-mm diam., 28 mm long) mounted in parallel. The heater probe contains a heating element while the sensor (mounted 6 mm from the heater) and reference probe (mounted 20 mm from the heater) contain thermocouples. The reference probe can be used to automatically correct for changes in background temperature. Measurements made at three depths during drying of a laboratory soil column yielded accurate changes in soil water content provided actual heater-to-sensor probe spacings were used in the calculations. We describe a simple procedure for checking on the probe spacings once the probes have been installed. These heat-pulse devices should prove useful for monitoring wetting or drying changes in soil water under both laboratory and field conditions.

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