The U.S. soil survey — contributions to soil science and its application

Abstract From the onset of surveys, characteristics and kinds of soils have had to be identified so that their distribution and extent could be determined. As an early entry in the field, the U.S. soil survey first recorded few characteristics and set apart broad, loosely defined kinds of soils. More characteristics were observed and recorded and more tightly defined kinds of soils were recognized as mapping and associated studies continued. The soil surveys thus generated progressively more knowledge. That in turn has contributed substantially to changes in the concept of soil, in theories of soil genesis, in standards and techniques for describing soils and in systems of soil classification. Initially considered the loose and weathered rock on the land surface, soil is now recognized as an organized natural system with a distinctive genetic history. Weathering as the full story of soil genesis has been replaced by the realization that many processes participate. Examples of contributions to the changes are cited in the main body of this paper. Furthermore, information on the distribution and extent of the kinds of soils has provided a geographic framework for planning and conducting research, for teaching, for extending the findings of research and experience from one place to another, and for applications of soil science. Illustrations of these are given in the paper.