Modeling of Flow, Transport, and Crop Yield in Spatially Variable Fields

Abstract

The traditional approach of modeling processes occurring in crop and soil systems is to apply macroscopic laws derived from laboratory scale, or small—field scale, to large—scale fields. Applications of such models to actual field conditions were supported by the assumption that the field can be regarded as a homogeneous or equivalent-to-homogeneous medium characterized by equivalent or effective soil properties that, in turn, are measured by sampling over a few locations in the particular field, and determined subsequently by an averaging procedure. Such an approach assumes that agreement between the outcome of the model for the fictitious homogeneous field and the process takes place in the actual, spatially variable field. It raises, however, the question of whether or not the variables (solute concentration, water content fluxes, crop yield, etc.), as depicted by the models, equal the average of the same variables prevailing in the field, and, if so, how to average the soil properties over the field to get such an equivalence. Also, is it sufficient to determine the average of these quantities (concentration, water flow properties, crop yield), or it is necessary to determine the confidence interval of the model results?