Soil Layers - Porosity Layers 1,2, and 3

Soils from FAO

     Soil properties were obtained from the FAO Soil Program which provides bulk density, sand and clay content, moisture contents and other variables. From sand and clay content, each 1/12 degree pixel grid cell is assigned to one of the twelve FAO soil textural classes. Soil hydrologic parameters were estimated from the USDA soil texture class. These includes: porosity, saturated hydraulic conductivity, field capacity and wilting point.

     Depths of 10, 20 and 120 cm were used as initial values for the soil layers one to three respectively. These values were changed to the values obtained after model calibration. Other soil parameters were either computed from those already obtained; for instance, particle density computed from Bulk density and porosity or recommended values from previous studies were used; for instance soil thermal damping depth for which 4 m is a recommended value.