Soil thermal properties

Additionally there is a time delay as to when maximum and minimum temperatures are achieved at increasing soil depth (sometimes referred to as thermal lag).

One possible way of assessing soil thermal properties is the analysis of soil temperature variations versus depth Fourier's law, where Q is heat flux or rate of heat transfer per unit area J·m−2∙s−1 or W·m−2, λ is thermal conductivity W·m−1∙K−1; dT/dz is the gradient of temperature (change in temp/change in depth) K·m−1.

The dual probe device is inserted into the soil and a heat pulse is applied and the temperature sensor records the response as a function of time.

Remote sensing from satellites, aircraft has greatly enhanced how the variation in soil thermal properties can be identified and utilized to benefit many aspects of human endeavor.

The various methods of measuring soil thermal properties have been utilized to assist in diverse fields such as; the expansion and contraction of construction materials especially in freezing soils, longevity and efficiency of gas pipes or electrical cables buried in the ground, energy conservation schemes, in agriculture for timing of planting to ensure optimum seedling emergence and crop growth, measuring greenhouse gas emissions as heat effects the liberation of carbon dioxide from soil.

Soil thermal properties are also becoming important in areas of environmental science such as determining water movement in radioactive waste and in locating buried land mines.

[2] Furthermore, MCS design criteria for shallow loop ground source heat pumps require an accurate in situ thermal conductivity reading.