Open hardware portable dual-probe heat-pulse sensor for measuring soil thermal properties and water content

A portable probe based on open hardware architecture for the assessment of soil thermal properties and water content using the DPHP method is presented. The mean percentage errors for assessment of volumetric heat capacity and thermal conductivity were 4.6% and 8.9% respectively, computed after sensor spacing calibration in agar stabilized water. The DPHP probe has been tested for soil thermal properties assessment and compared to TDR probe for the water content estimation in four different soils. The DPHP probe showed an accuracy comparable to TDR in estimating water content, with DPHP showing lower values of error index in 3 samples out of 4. The DPHP can be used to investigate smaller volume of soil than TDR probe can do however, TDR is much faster than DPHP in measure acquisition.