Thermal diffusivity of Lammelic Arenosols as related to soil moisture

This study presents the thermal diffusivity vs. moisture content curves for sandy soils of the East European Plain. Nine undisturbed soil cores 70 mm in height and 50 mm in diameter were studied in laboratory using the unsteady-state method. Thermal diffusivity of air-dry samples varied from 2.30×10⁻⁷ to 4.16×10⁻⁷ m² s⁻¹. The experimental moisture content – thermal diffusivity dependencies demonstrated pronounced peaks at 0.03−0.10 m³ m⁻³ moisture contents. Peak values of thermal diffusivity were from 8.25×10⁻⁷ to 9.86×10⁻⁷ m² s⁻¹. Statistical analysis was performed for 23 sandy samples including the newly studied ones and those earlier investigated with the same unsteady-state method. The ranges of sand, silt, and clay within the whole dataset were 73−97, 0−25, and 1−6%; wet bulk density varied from 1270 to 1820 kg m⁻³, organic carbon ranged from 0.1 to 1.7%. Each experimental curve was parameterized with a 4-parameter function. The parameters of average moisture content – thermal diffusivity dependencies were also obtained for (1) all sandy soils, (2) sandy soils with organic carbon content of 0.5% and greater, (3) sandy soils with organic carbon content less than 0.5%.