Numerical Taxonomy of Soils from Nine Orders by Cluster and Centroid‐Component Analyses

Abstract

Multivariate statistical procedures of numerical taxonomy were used to investigate the patterns of similarities among 59 soils. Twenty‐one morphological and laboratory characteristics of modal soil profiles from nine orders of the new classification system were used. Characters were selected to avoid high intercorrelations. Raw character values were transformed to give each character a mean of zero and variance of unity. Centroidcomponent analysis with projections of soils onto centroidcharacter axes was employed. This facilitated expression of similarities among soils in three dimensions in a manner which did not assume that clusters of soils existed. Correlation and distance matrices also were computed to obtain two estimates of the similarity of each individual to every other. Similarities among soils as indicated by these two matrices were summarized by cluster analysis. Results were displayed in phenograms yielding a system of nested clusters of soils.The three methods of estimating and summarizing similarity relationships gave comparable results. The numerical classifications agreed, in general, with the new classification system with respect to Mollisols, Alfisols, Inceptisols, Entisols, and Spodosols. Vertisols showed little affinity for one another, Aridisols clustered with Mollisols and Alfisols, and the single Oxisol clustered with Ultisols. Ultisols showed no special affinity for other Ultisols. Numerical taxonomic methods are capable of summarizing large amounts of new data efficiently, making them a valuable soil classification tool.

Sodium-affected alfisols of the agreste region, state of Paraíba, Brazil, as known by potter-farmers and agronomists

“…Previous studies where multivariate analysis was applied to pedological and ethnopedological data treated the "individuals" as soil profiles (Cipra et al, 1970;Queiroz & Norton, 1992;Vaselli et al, 1997), topsoil layers (Williams & Ortiz-Solorio, 1981) or treatments applied on soils such as farming systems (Quiroga et al, 1998;Silva et al, 2001), among others. However, in this particular case, the "individuals" analyzed and compared were sections (horizons and layers) found in the profiles of some soils (Alfisols) that have been used for multi-crop farming and earthenware production.…”

“…Ethnopedological studies attempt to support this pursue since they may provide more in-depth understanding of the relationship among humans, soils and other constituents of the ecosystems . The rationale is that social groups tend to assign different meanings to soils (Brady, 1989;Krasilnikov & Tabor, 2003;Cooper et al, 2005), and that decisions and practical attitudes of use and management adopted by these groups are based on their specific knowledge and cosmovision. These are generally transmitted through generations without necessarily using written language (Toledo, 2000).…”

Soil colour: its measurement and its designation in models of uniform colour space

“…Supplementary charts of redder Hues, 7.5R and 5R are available; consequently other authors have used similar scales starting at different Hues (e.g. Russell & Moore, 1976;Cipra et al, 1970;Campbell et al, 1970;Norris & Dale, 1971;Webster & Butler, 1976) or have extended the scale to include the gley colours also (Cuanalo & Webster, 1970;Muir et al, 1970). It is implicit in these scales that differences of one unit of Hue, one unit of Value and one unit of Chroma are all perceptually equal and that the co-ordinates of these scales are mutually orthogonal.…”

Analysis techniques in the study of soil distribution

“…to examine the interrelationships of 23 Glamorganshire profiles, producing results similar to those of the soil surveyor. Cipra et al (1970) used the coordinate method to represent the similarity of soils rather than use a classification technique, the latter necessitating assumptions that clusters already exist and can be distinguished. Anderson ( t g7 i ), in discussing multivariate analysis of soil samples, suggested that the requirement of orthogonal projections, basic to many ordination solutions, places an arbitrary restraint on the solution.…”