USDA Soil Taxonomy Flashcards

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Questions and Answers

What is Soil Taxonomy?

Classification of soil types based on their properties and was developed by the United States Department of Agriculture and the National Cooperative Soil Survey.

What was the original purpose of soil taxonomy?

To serve the purposes of soil surveys.

How many levels or hierarchies are there for soil taxonomy?

Six; Order, Suborder, Great Group, Subgroup, Family, Series.

How many recognized orders are there in soil taxonomy?

<ol start="12"> <li></li> </ol> Signup and view all the answers

Orders in soil taxonomy are divided into (blank) primarily on the basis of properties that influence soil formation.

Suborders. Signup and view all the answers

Each suborder is divided into (blank) determined by close similarities in kind, arrangement, and extent of soil horizon development.

Great Groups. Signup and view all the answers

What is a subdivision of a great group in soil taxonomy?

Subgroup. Signup and view all the answers

What is the division called within a subgroup determined primarily on the basis of physical and chemical properties?

Family. Signup and view all the answers

What does a series consist of in soil taxonomy?

Soils that have horizons similar in color, texture, structure, reaction, consistence, mineral and chemical composition. Signup and view all the answers

Name the recognized soil orders.

Alfisols, Andisols, Aridsols, Entisols, Gelisols, Histosols, Inceptisols, Mollisols, Oxisols, Spodosols, Ultisols, Vertisols. Signup and view all the answers

What are Alfisols?

Moderately leached deciduous forest soils that have relatively high fertility and contain a subsurface horizon in which clay has accumulated. Signup and view all the answers

What are Andisols?

Soils formed from volcanic activity, typically dominated by glass and poorly crystalline colloidal materials, very fertile. Signup and view all the answers

What are Aridsols?

Soils that contain calcium carbonate and are characteristic of arid regions. Signup and view all the answers

What are Entisols?

Soils of recent origin consisting of unaltered parent material usually with no genetic horizons, except an A horizon. Signup and view all the answers

What are Gelisols?

Soils of very cold climates that contain permafrost within 2 meters of the surface. Signup and view all the answers

What are Histosols?

Soils composed mainly of organic materials containing at least 20-30% organic matter. Signup and view all the answers

What are Inceptisols?

Soils that exhibit minimal horizon development but lack features and characteristics of other soil orders. Signup and view all the answers

What are Mollisols?

Soils of grassland ecosystems characterized by a thick, dark surface horizon known as mollic epipedon. Signup and view all the answers

What are Oxisols?

Very highly weathered soils found primarily in tropical regions with extremely low fertility. Signup and view all the answers

Study Notes

Soil Taxonomy Overview

Soil Taxonomy is a classification system developed by the USDA and National Cooperative Soil Survey to categorize soil types based on their characteristics.
Its original purpose was to facilitate soil surveys.

Structure of Soil Taxonomy

Composed of six hierarchical levels: Order, Suborder, Great Group, Subgroup, Family, and Series.
There are 12 recognized soil orders, categorized primarily based on properties influencing soil formation.

Levels of Hierarchy

Orders are divided into Suborders based on formation properties.
Each Suborder is further divided into Great Groups determined by similarities in soil horizon development, moisture and temperature regimes, and other properties.
Sub Groups are subdivisions of Great Groups.
Families are divisions within Subgroups based on physical and chemical property similarities.
Series consists of soils with similar profiles in color, texture, structure, and composition.

Soil Orders

Alfisols: Moderately leached, fertile soils with clay accumulation; found in the central U.S. and temperate humid regions.
Andisols: Volcanic soils rich in glass and colloidal materials; high water retention and very fertile, but phosphorus fixation is a concern in tropical regions.
Aridsols: Soils of arid regions with calcium carbonate and low organic matter; exhibit some horizon development.
Entisols: Recent soils with little alteration from parent materials; found in diverse ecological settings.
Gelisols: Cold climate soils containing permafrost within 2 meters; located in polar and high mountain regions.
Histosols: Organic-rich soils (20-30% organic matter); low bulk density and form in wetland environments.
Inceptisols: Minimal horizon development; more developed than Entisols; found in various ecological settings.
Mollisols: Grassland soils characterized by thick, dark surface horizons due to organic matter accumulation; prevalent in middle latitudes.
Oxisols: Highly weathered tropical soils; low fertility and nutrient retention, rich in iron and aluminum oxides.
Spodosols: Acid soils with iron and aluminum accumulation in subsurface horizons; light-colored E horizon above a reddish-brown spodic horizon.

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Description

Test your knowledge of soil taxonomy with these flashcards. Learn about the classification systems developed by the USDA and their purposes. This quiz covers key concepts and definitions related to soil types and their hierarchies.