Easy Concepts, Hard Definitions—Soil Taxonomy, a Book with a Hundred Coauthors.

Which definition is the harder: the mollic epipedon or Einstein’s’ general theory of relativity? Some would say the mollic epipedon is the harder definition, but general relativity is the harder concept. Likewise, consider a soil on a river floodplain (which is a straightforward idea), but what properties do you measure to capture that idea and how must the definition be written to exclude all other soils? This was the challenge for Guy Smith, the national soil survey staff, and hundreds of soil mappers. Add to this challenge a system that is designed, in part, to classify nature and, in part, to classify utilitarian properties important for management, especially agricultural management. Herein lies the reason for the hard and sometimes indecipherable definitions. Still, Soil Taxonomy is elucidating, even elegant, because it’s quantitative, it’s hierarchical, and its structure is logical. It conveys volumes about how soils differ across the landscape. Consequently, there is an opportunity for soil taxonomists today is to translate this understanding and use Soil Taxonomy as tool for solving scientific and environmental problems.