Abstract
Diurnal soil temperature fluctuation in a bare field was analyzed with a model which included heat exchange at soil surface, heat conduction in soil, and evaporation through dry layer. The measured solar radiation, soil thermal conductivity, water content profile and daily evaporation rate were used as input data. The soil temperature calculated by the model agreed well with those measured in various meteorological and soil conditions
Then, the effect of thickness of surface dry layer on the soil temperature was examined with this mode. As the result, developing of the dry layer increases temperature amplitude in the dry layer but decreases the amplitude in wet layer beneath the dry layer because the dry layer has high thermal resistance while it reduces evaporation rate.
