Soil survey

Soil survey, or soil mapping, is the process of determining the soil types or other properties of the soil cover over a landscape, and mapping them for others to understand and use. It applies the principles of soil science, and draws heavily from geomorphology, theories of soil formation, physical geography, and analysis of vegetation and land-use patterns. Primary data for the soil survey are acquired by field sampling, supported by remote sensing, (principally vertical airphotos).
See more at Wikipedia.org...

A program of the Natural Resources Conservation Service to inventory soil resources as a basis for determining land capabilities and conservation treatments that are needed, provide soil information to the public (primarily through maps), and provide technical support to those who use soils information. About 90% of the private lands have been mapped. In FY1996, maps were prepared or updated on more than 17 million acres.