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 wro ng level of resolution. A method is proposed for aggregating the value s of individual soils to the level of the soil association. This metho d involves creating frequency distributions based on the recorded prop erties of the individual soils within the association, and then approx imating this distribution by the use of a beta-function. In multiple s imulation runs, this method allows the inclusion of the soil variabili ty found in the soil association while modeling crop response over the area of the association.