PREDICTING TEMPERATURES OF BARE AND RESIDUE COVERED SOILS WITH AND WITHOUT A CORN CROP.

Models are described to predict the upper boundary and root zone temperatures for bare and various residue-covered soils with and without a growing corn crop. The model for predicting upper-boundary temperatures is based on the assumption that the difference between hourly air temperature at the 2-m height and the soil surface temperature follows a sine function. The root zone temperature model is based on the numerical approximation of heat flow equation and uses the estimated upper boundary temperatures as an input for its prediction. Thermal diffusivities are estimated from soil mineralogy, organic matter percentage and bulk density data, and field measurements of matric potential.