Soil Classification Chapter 3 Flashcards

Soil Classification Overview

• Soil classification helps predict soil behavior and manage land effectively.
• The USDA-NRCS classification system is used in over 50 countries worldwide.

Soil Development Factors

• CLORPT is an acronym for the five factors of soil development: Climate, Organism, Relief, Parent Material, and Time.

Soil Taxonomy Structure

• Soil taxonomy contains six levels: Order, Suborder, Great Group, Sub-group, Family, and Series.

Types of Soil

• Muck: Decomposed material with high humidity content.
• Soil orders represent the most general classification category.

Texas Soil Series

• Over 1,300 soil series identified in Texas, classified into nine soil orders.
• Seven prominent orders include Alfisols, Aridisols, Entisols, Inceptisols, Mollisols, Ultisols, and Vertisols.

Soil Order Characteristics

• Alfisols: Nutrient-rich, productive for crops, comprise about 10% of global land.
• Andisols: Volcanic glass content, high water retention, make up about 1% of global land.
• Aridisols: Found in desert areas, low moisture, make up 12% of global land.
• Entisols: Recently formed soils lacking horizon development, make up 16% of global land.
• Gelisols: Contain permafrost, found in cold regions, comprise 9% of global land.
• Histosols: Organic-rich, saturated soils, found in bogs and wetlands, make up 1% of global land.
• Inceptisols: Moderately weathered, diverse characteristics, make up 17% of global land.
• Mollisols: Dark soil, high organic content, found primarily in grasslands, make up 7% of global land.
• Oxisols: Highly weathered, found in tropical areas, make up 8% of global land.
• Spodosols: Acidic subsoils found under coniferous forests, make up 4% of global land.
• Ultisols: Formed in humid areas, susceptible to weathering, make up 8% of global land.
• Vertisols: Have shrink-swell clay, high fertility, make up about 25% of global land.

Mapping and Assessment Techniques

• Soil series characterized by a range of properties, named for first identification location.
• Houston Black Soil designated as the Texas State Soil.
• Soil surveys involve systematic examination and mapping of soil characteristics.
• Soil pits allow detailed examination of soil profiles, including color, texture, and structure.

Land Capability Classes

• Class I: Versatile, low erosion risk, deep, well-drained soils suitable for a variety of crops.
• Class II: Requires careful management; few limitations for crops.
• Class III: Designated as prime farmland for producing food and fiber.
• Class IV: Limited plant choices and requires careful management.
• Class V: Soil limitations restrict certain crops; often wet or stony.
• Class VI: Unsuitable for crops but viable for special uses like orchards.
• Class VII: Impractical for management improvements in pastures or ranges.
• Class VIII: Unproductive for crops but may allow recreational activities.

Permafrost

• Defined as soil, rock, or sediment frozen for over two consecutive years, typically found in extremely cold climates.

This quiz focuses on the classification of soils as outlined in Chapter 3. It covers key terms and definitions related to soil classification systems including USDA-NRCS and the factors affecting soil development. Perfect for students seeking to deepen their understanding of soil science concepts.