Principles of Soil Classification Quiz

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Questions and Answers

Who organized soils into groups with similar observable properties based on broad climatic zone?

US Department of Agriculture

V.V Dokuchaev (correct)

Soil Survey

CF Marbut

What is the term used to refer to the system of soil classification developed by the US Department of Agriculture?

Pedon

Soil Taxonomy (correct)

Polypedon

Soil Series

What is a pedon?

An area with multiple polypedons

A column of soil used in surveys (correct)

A class of soils

A basic sampling unit used in soil surveys

What does a polypedon comprise?

Identifiable series of soils in an area Signup and view all the answers

Who developed a soil classification scheme in the 1920s?

CF Marbut Signup and view all the answers

What is a soil series?

A class of soils and the basic units used to classify soils Signup and view all the answers

What is the purpose of Soil Taxonomy?

To organize knowledge about soils, understand relationships, and establish groups for practical purposes Signup and view all the answers

What does Soil Taxonomy use to subdivide soil order into suborders?

Moisture and temperature regime Signup and view all the answers

What is the primary purpose of Diagnostic Horizons in Soil Taxonomy?

To reflect the nature of soil formation Signup and view all the answers

What is the main characteristic of the Spodic horizon?

Illuvial accumulation of oxides of Al and Fe, and OM, red or dark red color Signup and view all the answers

What distinguishes the Oxic horizon in tropical soils?

Very weathered layer of only Fe and Al oxides and 1:1 clay minerals, low pH, and not very fertile Signup and view all the answers

What is the primary characteristic of the Cambic horizon?

Slightly altered layer, not weathered enough to be argillic Signup and view all the answers

In Soil Taxonomy, what is used to categorize soils into six distinct categories?

Presence or absence of diagnostic horizons Signup and view all the answers

What is the purpose of the Principles of Soil Taxonomy?

To classify soils based on properties Signup and view all the answers

What do Temperature Regimes in Soil Taxonomy refer to?

Mean annual soil temperature measured at 50 cm from surface Signup and view all the answers

What is the primary characteristic of the Natric horizon in Soil Taxonomy?

Same as argillic but with > 15% exchangeable sodium (Na) Signup and view all the answers

Study Notes

Soil Classification and Development

Soils were organized into groups with similar observable properties based on broad climatic zones by the US Department of Agriculture (USDA).
The system of soil classification developed by the USDA is known as Soil Taxonomy.
A pedon is defined as the smallest unit of soil that can represent the characteristics of a particular soil type, typically a 1-meter square area extending vertically through soil layers.
A polypedon comprises multiple pedons that share similar properties and are grouped together to form a specific soil mapping unit.

Historical Contributions

A soil classification scheme was developed in the 1920s by the USDA to improve soil understanding and management.
A soil series represents a group of soils that have similar profiles and properties, often named after a geographic location.

Purposes and Functions of Soil Taxonomy

The purpose of Soil Taxonomy is to provide a systematic framework for categorizing and interpreting soils based on their characteristics and behaviors.
Soil Taxonomy uses various criteria to subdivide soil orders into suborders, typically based on properties like moisture, temperature, and genesis.
The primary purpose of Diagnostic Horizons in Soil Taxonomy is to identify specific layers within the soil profile that reflect certain physical and chemical characteristics, which aid in classification.

Specific Soil Horizons

The Spodic horizon is characterized by the accumulation of illuviated organic matter and iron and aluminum oxides.
The Oxic horizon, typically found in tropical soils, is distinguished by its highly weathered, low-activity clay and high degree of leaching.
The primary characteristic of the Cambic horizon is its minimum alteration from the parent material, reflecting initial soil formation processes.

Categorization and Principles

Soil Taxonomy categorizes soils into six distinct categories known as soil orders based on inherent properties and characteristics.
The purpose of the Principles of Soil Taxonomy is to establish standardized criteria for soil classification, ensuring consistency and reliability in soil science.
Temperature Regimes in Soil Taxonomy refer to climatic conditions influencing soil temperature, which play a significant role in soil formation and classification.
The primary characteristic of the Natric horizon includes a significant accumulation of sodium-rich clay and often demonstrates a unique clay-rich structure, affecting drainage and fertility.

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Description

Test your knowledge about the principles of soil classification, including the history of classification systems and key contributors like V.V. Dokuchaev and CF Marbut. Explore the development of soil taxonomy and its formal terminologies.