Expanded and Updated Thermal Property Data for a Biochar-Amended Soil.

Biochar has been proposed as a key component for developing sustainable agronomic-biomass-bioenergy production systems.  Due to its unique physical properties, high surface area and low bulk density, biochar is thought to improve a range of soil physical properties such as total porosity, pore-size distribution, soil bulk density, soil moisture content, water holding capacity, and plant available water.  Reductions in soil bulk density and increases in soil moisture retention due to the application of biochar to soil, can potentially alter the surface energy balance and soil heat flux leading to changes in the amount of energy available for soil water evaporation. Quantification of heat transfer in biochar amended soils requires accurate knowledge of thermal properties and their dependence on soil moisture.  Therefore, the objective of this laboratory study is to measure the soil thermal properties (thermal conductivity, volumetric heat capacity, and thermal diffusivity) of two soils amended with varying amounts and particle sizes of biochar.  Biochar is mixed with a Decatur silt loam and Hartsells sandy loam at 0, 1, 2, 4, and 8% on a mass basis.  A dual-probe heat-pulse is used to measure the soil thermal properties.  Analysis of variance (ANOVA) is performed to determin and report the differences in soil thermal properties due the addition of the biochar to the two soils.