A GEOSTATISTICAL DESCRIPTOR OF THE SPATIAL-DISTRIBUTION OF SOIL CLASSES, AND ITS USE IN PREDICTING THE PURITY OF POSSIBLE SOIL MAP UNITS

A geostatistical descriptor of the spatial distribution of soil profil e classes is discussed, the Sum of Indicator Variograms (SIV). This fu nction may be estimated for a region from observations of the soil pro file class occurring at a systematic array of sample sites, and fitted by an authorised variogram model. It is shown that the fitted variogr am model can be used, given some simplifying assumptions, to predict t he average purity of map units for a soil map of the region with a leg end of simple units corresponding to the profile classes. An indicatio n of the mean boundary interval of alternative maps is also given by t he variogram model, although this should be treated with caution. The method proposed could,therefore be useful when analysing observations from a reconnaissance soil survey, as an aid to selecting appropriate methods for more detailed survey. (C) 1998 Elsevier Science B.V.