Thermal diffusivity of typical Chernozems in the Kamennaya Steppe reserve

Abstract

The thermal diffusivity of medium-deep light clayey typical chernozems (Voronic Chernozems (Pachic, Clayic)) has been studied, which varies with the soil water content in the ranges of (0.77–2.88) × 10−7 m2/s for the Ap horizon, (0.82–2.60) × 10−7 m2/s for the Ad horizon, (0.86–2.58) × 10−7 m2/s for the A1 horizon, (0.78–2.31) × 10−7 m2/s for the A1’ horizon, (0.81–2.87) × 10−7 m2/s for the AB horizon, (1.01–3.33) × 10−7 m2/s for the B horizon, and (0.98–3.26) × 10−7 m2/s for the Bca horizon. The dependences of the thermal diffusivity on the water content are described by S-shaped curves with a long gently sloped segment in the region of volumetric water content below 0.15 cm3/cm3, a region of pronounced increase of thermal diffusivity in the water content range from 0.15 to 0.30–0.35 cm3/cm3, and the cessation of the increase or even some decrease in the water content range above 0.30–0.35 cm3/cm3. The approximation of the experimental curves has allowed developing a set of pedotransfer functions, which reflect the differences between the horizons and can be used for the quantification of the thermal diffusivity of the studied horizons at any water content.