Soil Heat Transducers and Water Vapor Flow

The heat flow through a silt loam, silty clay, and loamy sand were measured in a calorimeter at 7 and 36°C under matrix potentials near -0.3 bars. The transient thermal conductivity probe, the heat flux transducer, and deVries's theoretical method all gave low values of the apparent thermal conductivity at 36°C. An empirical correction was proposed for deVries's method that improved its agreement with the observed conductivities. The thermal vapor diffusion coefficients for the three soils were then calculated from his equation and compared with experimental values from the calorimeter. It was also shown that the thermal water vapor flow can be estimated if one knows the soil's saturated thermal conductivity, quart/ content, water content, bulk density and temperature distribution.