SW--Soil and Water: Measurement of the Thermal Conductivity of Sandy Loam and Clay Loam Soils using Single and Dual Probes

The propagation of heat in soil is governed by its thermal characteristics. The ability to monitor soil thermal conductivity is an important tool in managing the soil temperature regime to affect seed germination and crop growth. The effect of bulk density and moisture content on the thermal conductivity of two sieved and repacked soils was investigated through laboratory studies. These laboratory experiments used the single-probe and dual-probe methods to measure and compare thermal conductivities. The soils used were classified as sandy loam and clay loam. Thermal conductivity increased with increasing soil density and moisture content. Thermal conductivity measured by the single-probe method ranged from 0·19 to 1· 13 for sandy loam and from 0·35 to 0·69 W m-1K-1for clay loam at densities from 1·25 to 1· 49 g cm-3and water contents from 7·2 to 18·2%. Thermal conductivity measured by the dualprobe method ranged from 0·21 to 1·15 for sandy loam and from 0·37 to 0·70 W m-1K-1for clay loam at same densities and water contents. Finally, it was found that the sandy loam had higher values of thermal conductivity than the clay loam for the soil conditions studied.