Question: The USDA Soil Taxonomy system classifies soils into hierarchical categories. How many levels, or categories, are there in this classification system?
Options:
4
6
8
10
The USDA Soil Taxonomy system employs a hierarchical classification scheme consisting of six categories, arranged from most general to most specific.
• The Six Levels of Soil Taxonomy:
-Order: The broadest level, encompassing soils with fundamental similarities in genesis (formation) and morphology (physical characteristics). (e.g., Alfisols, Mollisols)
-Suborder: A subdivision within an order based on more specific properties. (e.g., Aqualfs (wet Alfisols), Ustalfs (moist Alfisols))
-Great Group: A further refinement within a suborder, considering additional differentiating characteristics. (e.g., Hapludalfs (moderately well-drained Ustalfs))
-Subgroup: A category within a great group defined by even more specific properties. (e.g., Dystrudepts (Hapludalfs with spodic horizon))
-Family: A level focusing on soil texture (mineral composition of the fine particles). (e.g., Fine-silty, mixed, superactive, mesic Dystrudepts)
-Series: The most specific category, representing soils with very similar properties throughout the profile, including texture, drainage, mineralogy, and chemical properties. (e.g., Miami series)