Computer-based soil mapping of small areas from sample data I Multivariate classification and ordination

Summary A 1400 m ? 600 m rectangular area of north Berkshire had been sampled at the intersections of a 100 m square grid, and seventeen properties of the soil profile measured. The eighty-four sampling sites were classified numerically to produce a hierarchy, and the classes of the upper part of the hierarchy mapped. The mapped classes became increasingly fragmented as the number of classes increased. At the 3-class level, the classes corresponded to character space clusters and class fragmentation was not serious. Principal-component analysis of the sample data yielded a first component that accounted for 40 per cent of the total variance and well represented the field characters used for soil classification. An isarithm map of the first component shows how the soil changes gradually over the landscape in good agreement with a soil-series map made by free survey.