Difference in thermal conductivity at field capacity (FK) - Permanent withering point (PWP)

This map shows the mean thermal conductivity with water contents as the difference between field capacity (FK) and permanent wilting point (pF 4.2). It illustrates the water content-dependent differences between seasonally highest and lowest thermal conductivity and gives an impression of the expected seasonal dynamics of thermal conductivity at a site.
The differences are divided into the following classes:
Difference λFK - λPWP [W/m*K]
very low ≤ 0,2
low 0.21 - 0.40
medium 0.41 - 0.65
high 0.66 - 0.91
very high 0.92 - 1.20
Thermal conductivity (λ) determines the property of the soil to transport thermal energy through conduction. It is the decisive parameter for the use of the soil as a heat source and storage and must be taken into account, among other things, in the application of near-surface geothermal energy (earth heat collectors) or in the construction of underground power cables.