The first 4 levels of the US Soil Taxonomy hierarchy (soil order, suborder, greatgroup, subgroup), presented as a data.frame (denormalized) and a list of unique taxa.
data(ST)An object of class data.frame with 2665 rows and 9 columns.
Ordered based on the unique letter codes denoting taxa from the 13th edition of the Keys to Soil Taxonomy.
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service. U.S. Department of Agriculture Handbook 436. https://www.nrcs.usda.gov/resources/guides-and-instructions/soil-taxonomy
Soil Survey Staff. 2014. Keys to Soil Taxonomy, 12th ed. USDA-Natural Resources Conservation Service, Washington, DC. https://www.nrcs.usda.gov/resources/guides-and-instructions/keys-to-soil-taxonomy