Soil:Material classification' for paddy soils in japan

Abstract

In view of the importance of soil material characteristics in determining paddy soil capability, a method of classification for soil materials was proposed. In working out the method special attention was paid to making it practically applicable. for the need is great for such a method of ready practical applicability especially in the alluvial soil areas in which most Japanese paddy soils occur. An X-ray fluorescence spectrographic method for the total chemical analysis of soil materials proved satisfactory for routine use in terms of accuracy and time. Nine major elements (Si, Fe, AI, Ca, Mg, Mn, Ti. K, P) were analyzed and they were taken to represent the chemical nature of the aoil material. The total chemical composition was combined with mechanical composition and subjected to data processing. To avoid redundancy in information, 2 mutually independent principal components were extracted, which appear to represent different aspects of soil material features. From the 2 principal component scores taxonomic distance was computed as a similarity coefficient for use in numerical taxonomy. Dy means of numerical taxonomy 8 soil material classes were liet up, each of which was characterized in terms of texture, base status, weatherable mineral reserve., tc. In order to facilitate objective placement of a neW sample into one of the classes set up. discriminant functions were derived for all pairs of the 8 material classes. A figure.howing the discriminant Bpace that corresponds to the discriminant functions was prepared to make the practice of discrimination easy. The 8 soil material c1assf'S appear to represent major varieties of paddy soil materials in Japan. The use of the soil material classea as a basil or "soil family" separation in soil aurveys would improve the homogeneity of the lower taxonomic units ("soil series") and make their interpretation easier and more correct in relation to Boil capability aliliessment. © 1976 Taylor & Francis Group, LLC.