ABSTRACT
Digital soil mapping can reflect spatial continuity of soil properties that is believed to be a benefit of digital maps comparing with traditional maps of soil taxa. However, users may require a map of discrete polygons, which represent either taxonomic or functional soil classes. We analyzed the variability of pH and organic carbon in several soilscapes in Eastern Fennoscandia. The soilscapes with contrasting soil polygons were detected by a specific hump-like form of semivariograms rather than by high variation. The continual maps of soil properties may be transformed into discrete maps using indicative kriging. However, the resulting polygons hardly correspond to the limits of taxonomic soil groups, because the diagnostic properties of soil taxa seldom correlate with such properties as pH or organic carbon. We propose using functional rather than taxonomic groups for discrete digital soil mapping, concentrating on soil productivity, limiting factors for soil use and soil-related ecosystem services.
