A Background Temperature Correction for Thermal Conductivity Probes

A procedure is outlined for correcting the thermocouple reading of a thermal conductivity probe for changes in temperature caused by external warming or cooling of the soil during the period of measurement. A background temperature measurement is made for several minutes with the probe heater turned off, and the estimated temperature change due to the surroundings is then subtracted from the change caused by the probe heater. A laboratory experiment using a buried probe exposed to surface heating demonstrated a substantial reduction in the errors for the values of conductivity measured for a soil of known thermal properties when the correction was used.