Classifying Soil Types
Soil characteristics can help to predict crop performance, therefore it is useful to classify soils. The basis of soil classification is that environments that share comparable soil forming factors produce similar types of soil. The soil type at a given site is the long term consequence of all of the environmental factors, including geological ones, which have prevailed at that site. Knowing the soil type, therefore, gives us information about the above ground environment at the site as well as the substrate for plant growth.
Soils are classified by a taxonomic system, like plant taxonomy, based on relationships between soil types. Soil taxonomy has six hierarchical levels of classification as follows: orders, suborders, great groups, subgroups, families, and series.
The MNG Case Study Site Assessment Workbook  provides example soil survey information.
Beginning early in the 20th Century, the US Soil Conservation Service (now the Natural Resource Conservation Service, NRCS) began an extensive process of classifying and characterizing agricultural and other soils throughout the US. According to the NRCS, a soil survey is a “detailed report on the soils of an area”. NRCS soil surveys are available in print from local NRCS offices, local conservation offices and other sources described in the Soil Survey Resource box, below. A NRCS soil survey consists of:
Soil survey map (aerial photo) from Soil Survey of Tompkins County, NY. Red lines on the aerial photograph circumscribe different soil type denoted by abbreviations which correspond to the names soil types described in corresponding text and tables.
Locating and Using NRCS Published Soil Surveys
Surveys for your site may be available on the NRCS website  . If it is not, use the list of surveys by state to find out where you can obtain a print or CD version of the survey for your location  .
To use a published NRCS (SCS) soil survey (print or online):
Adapted from How to use Soil Surveys and Aerials Photos in Logging Operations, by Jim Ochterski, full text in resource box below.
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