Thermal conductivity of undisturbed soil – Measurements and predictions

•Soil thermal conductivity, λ, was measured with the heat pulse method for nine soils.•A polynomial expression fitted well λ variation with degree of water saturation, S.•λ for completely dry soil, λdry, ranged wider than in most studies.•Bulk density, clay and soil organic matter explained 87% of the variation in λ.•λ should be measured on undisturbed soil.