ABSTRACT
Early agrarian civilizations must have had some way to communicate differences and similarities among soils. The earliest documented attempt at a formal classification of soils seems to have occurred in China about 40 centuries ago. The Chinese system included nine classes based on productivity. After World War II, agriculture felt the effects of economic reconstruction and the expansion of global markets, and there was a renewed interest in soil conservation and alternative land uses, which helped invigorate soil survey activities. Soil scientists began identifying many new soils, and classification systems needed to track all the newly recognized soils. The diagnostic horizons and features represent a major innovation in soil classification that has been embraced by most pedologists, but there remain issues that have not been resolved to everyone’s satisfaction. Soils, unlike discrete plants or animals, form a continuum over the earth’s surface. Soil classification systems have evolved into sophisticated communication tools.
