Soil Temperature Simulation with Varying Residue Management

Maintaining crop residue on the soil surface is an important part of conservation tillage. Although broad effects of residues on soil temperature (T_s) are well documented, the methods to predict soil temperatures under various surface residues and tillage conditions are limited. Using the T_s at 0-, 0.05-, 0.10-, and 0.30-m depths, we developed a simplified model to predict T_s for a uniform soil from air temperature (T_a) data. Data were collected under various tillage and surface residue conditions after wheat ( Triticum aestivum L.) harvest. Residue management treatments were disk, sweep, and no-tillage (with standing or shredded residues). The model predicts maximum and minimum T_s at 0-, 0.05-, 0.10-, and 0.30-m depths using maximum and minimum T_s measured at 2-m above the soil surface, residue mass, apparent thermal diffusivity, and initial Ts profiles. Mean absolute deviation between simulated and measured maximum and minimum surface T_s were 0.53 and 0.44 °C or less, respectively. Root zone maximum and minimum T, were simulated within 0.14 to 0.91 and 0.27 to 0.95 °C, respectively, of the measured T_s. Greater precision of maximum and minimum soil temperature predictions with depth was obtained by using apparent thermal diffusivity calculated from initial T_s profiles. The proposed model can be useful in predicting T_s profiles required for crop growth modeling.