USE OF THE BETA-DISTRIBUTION FOR PARAMETERIZING VARIABILITY OF SOIL PROPERTIES AT THE REGIONAL LEVEL FOR CROP YIELD ESTIMATION

In order to use mechanistic crop models for regional estimates of crop yield it is often necessary to include soil parameters which may not be readily available from published sources or which may be at the wrong level of resolution. A method is proposed for aggregating the values of individual soils to the level of the soil association. This method involves creating frequency distributions based on the recorded properties of the individual soils within the association, and then approximating this distribution by the use of a beta-function. In multiple simulation runs, this method allows the inclusion of the soil variability found in the soil association while modeling crop response over the area of the association.