Evaluation of Heat Flux and Thermal Characteristics of Black Soil in Relation to Soil Moisture Content during Drying

Thermal characteristics of black cotton soil were computed from the temperature data recorded periodically at different depths with the help of a Bristol 2 channel temperature recorder and an eight-way switch. The results indicate that the thermal conductivity (λ) increased from 0.6 to 2.9 meal cm⁻¹ sec⁻¹ $$C⁻¹ arbitrarily exponentially as the moisture content increased from 0.20 to 0.37 cm³ cm⁻³ at 5 cm depth. The increase in A was rapid at low than at high soil moisture contents. Similarly increase in moisture content resulted in gradual acceleration of the thermal diffusivity up to a value of 3.92 cm² sec⁻¹ and thereafter it declined with the subsequent increase in moisture content beyond 0.40 cm³ cm⁻³ at 5 cm depth. The volumetric heat capacity increased linearly as a function of water content. The heat flux as influenced by soil moisture gradient increased linearly wiih a moisture content and a maximum value of 1.8 meal cm⁻² sec⁻¹ was recorded at saturation.