A soil temperature demonstration

ABSTRACT An exhibit was constructed to demonstrate the effects of soil moisture on the heat capacity and thermal conductivity of two different soils. Four soil columns were fitted with thermistors at depths of 0 to 1, 5, and 10 cm below the soil surface. Half the columns were saturated with water and the other half were left air‐dry. A heat source was applied to the top of the columns, and the temperatures in the columns were measured periodically. For a sand and a silty clay soil, the surface of the dry soils warmed up faster and to a higher temperature than the saturated soils while the subsoil generally warmed up at an equal or faster rate in the saturated soils. Based on this information, a number of questions were posed to students concerning the effects of soil moisture on the thermal properties of soils.