Soil Temperature Estimation by a Numerical Method

A numerical method for computing soil temperature as a function of time and depth was devised. The method allows for variable soil properties as a function of depth and requires measurement of soil temperature at or near the soil surface. Computed and measured soil temperatures agreed within 1.0C when actual soil thermal properties were used for the computation. Computed and measured soil temperatures agreed within 1.5C when soil thermal diffusivity was assumed constant at 0.20 cm 2 min ‐1 . Actual values varied with depth from 0.21 to 0.29. Where the thermal diffusivity was assumed uniform at 0.45 cm 2 min ‐1 , temperature errors grew from 1.0–1.7C after 3 days to 1.7–3.1C after 6 days.