Evaluation of Thermal Diffusivity of Soil Near the Surface: Methods and Results

University of Ruse, BG – 7017 Ruse, Bulgaria


EVSTATIEV, B., 2013. Evaluation of thermal diffusivity of soil near the surface: methods and results. Bulg. J. Agric. Sci., 19: 467-471


In the present study has been developed a method for evaluation of the mean daily thermal diffusivity of soil, assuming it is vertically inhomogeneous. The method uses data for the temperature variation of soil at three depths. Additionally the soil surface heat flow has been defined as a function of the thermal conductivity and thermal diffusivity coefficients. The method’s performance conditions have been defined and their critical value has been determined for sensors with accuracy 0.1 °C. The method performance has been validated using data for the soil temperature variation at depths 1 cm, 10cm and 20 cm, acquired experimentally on the territory of the University of Ruse. The soil thermal diffusivity has been evaluated using the developed method and the harmonics method, considered to be the most reliable one. The results showed that the new method gives more accurate results than the harmonics one for days with low temperature amplitudes and for days with changing weather conditions.

Key words: soil temperature, thermal diffusivity, soil heat flow

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