Amendments to Soil Taxonomy - Approved, Pending, and Proposed Since Publication of 12th Keys in 2014.

Soil Taxonomy is a dynamic soil classification system designed to support making and interpreting soil surveys. It has been in use in the United States since 1975 having evolved from earlier soil classification systems, including its predecessor the Seventh Approximation. Soil Taxonomy has been formally expanded upon and republished as a set of Keys to Soil Taxonomy 12 times since 1975, the latest in 2014. Amendments and expansions to the Keys to Soil Taxonomy continue today. Regional NCSS Conferences Committees in 2014 and 2016, as well as the 2016 NCSS National Conference have introduced, vetted, and added new taxonomic classes and clarified issues discovered in application of Soil Taxonomy in the field.

To date, 18 additions to taxa, changes to definitions, and clarifications have been approved for use to classify soil since the release of the 12^th Keys in 2014. Currently, 14 proposals to add or redefine classes are under consideration in the review and vetting process. Several other significant issues to Soil Taxonomy have been raised needing additional investigation and evaluation in order to develop concise proposals for amendment. Among the significant enhancements under consideration are the establishment of an Aquasol order for subaqueous soils, and the addition of two diagnostic epipedons for use in arid regions having vesicular surface horizons (yermic) and for unvegetated soil surfaces associated with desertic playas, vernal pools, and clay flats (takyric).

Also under consideration in Soil Taxonomy is the role and position of the soil moisture regime in the taxonomic classes and heirchy. This longer-term evaluation and assessment will include annual “Soil Taxonomy Field Meetings” to provide background and input in how soil moisture regime is used in the making and interpreting of soil surveys.