Impact of spatial variability on interpretive modeling.

This chapter summarize modes, magnitudes and forms of spatial variability in soil systems and to explore consequent impacts on modeling. It highlights interpretive use of pedologic data in terms of modeling crop growth, water regimes and the associated land qualities. Spatial variability in soil systems belongs to two broad categories: systematic and random. Users of soil surveys and modelers frequently wish to know the relative magnitude of soil property variability. Several modeling attempts have been reported using soil map delineations as a means to express spatial variability patterns, using "representative" soil profiles for each delineation. The functional analysis focuses implicitly on mapping units as homogeneous "carriers" of information. Comprehensive use of the soil survey data bases for modeling will rely heavily on the development of continuous and class pedotransfer functions. The data base will contain single values for other soil parameters represented as ranges in the Soil Conservation Society soils interpretations record data base.