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Soil Classification

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Soil TaxonomySoil scientists describing a soil profile.

Soil Taxonomy - principal reference to soil classification.

Keys to Soil Taxonomy - taxonomic keys for field classification.

Soil Taxonomy Forum

WRB Teaching Materials


Soil Series

Links to Official Soil Series Descriptions (OSD), Soil Series Classification Database (SC), SC/OSD Maintenance Tool, and Soil Classification Report Tool have been moved to Tools & Data.


Java Newhall Simulation Model (jNSM) –  A traditional soil climate simulation model (software, user’s guide, and sample datasets)

Historical Documents

Previous versions of the Keys to Soil Taxonomy

The Guy Smith Interviews: Rationale for Concepts in Soil Taxonomy
    — The Post Guy Smith Interviews: Advances in Soil Taxonomy Since the Mid-1980s

Development and Significance of the Great Soil Groups of the United States (PDF; 5.82 MB) by Charles E. Kellogg; published in 1936

1918-1922 Soil Classification Keys for the Soil Provinces and Soil Regions of the United States (PDF; 800 KB)

Historical International Committee Recommendations (ICOMFAM, ICOMID, etc.)

Media Files

Distribution Maps of Dominant Soil Orders - images and maps.

The Twelve Orders of Soil Taxonomy - poster.

Other Classification Systems

Universal Soil Classification System - a Working Group under Commission 1.4 (Soil Classification) which is part of Division 1 (Soil in Space and Time) of the International Union of Soil Sciences (IUSS)

World Reference Base (WRB) - The WRB, along with Soil Taxonomy, serve as international standards for soil classification. The WRB system is endorsed by the International Union of Soil Sciences and developed by an international collaboration coordinated by the IUSS Working Group. The WRB borrows heavily from modern soil classification concepts, including Soil Taxonomy, the legend for the FAO Soil Map of the World 1988, the Référentiel Pédologique, and Russian concepts.