Soil Orders and Classification Flashcards

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Study Notes

Entisols

Least weathered soil type with minimal horizon development.
Formed from the youngest parent materials like landslide deposits or freshly disturbed forest areas.
Characterized by the absence of distinct B horizon; typically features only an A horizon.
Not specific to any biome, making it one of the most common soil types.

Inceptisols

Mid-level weathered soils with slight horizon development.
Possess a dark organic layer called an umbric layer but contain minimal organic material.
Distributed widely across various landscapes.

Andisols

Most weathered soil among low weathering types, primarily formed from volcanic lava.
Commonly located around the Pacific Rim, notable in regions like Hawaii and Japan.
Exhibits unique properties, including high water-holding capacity and the ability to make phosphorus unavailable to plants.

Gelisols

Less weathered soils characterized by the presence of permafrost.
Formed from organic matter and contain no distinct B horizon.
Rich in organic matter yet hold minimal minerals; found in high-latitude polar regions.

Histosols

Soil type rich in organic material, typically found in wetlands, peatlands, swamps, and marshes.
Features a thick O horizon that exceeds 40 cm and comprises at least 20-30% organic matter by weight.
Contains no bedrock beneath the surface.

Aridisols

Intermediate weathering soil type found in arid and desert regions.
Characterized by low carbon content and indistinguishable horizons due to slow soil development.
Limited vegetative cover results from minimal rainfall, hindering chemical weathering.

Vertisols

Intermediate weathering soil type associated with high base status and high activity clays.
Typically found in wetter areas; exhibits significant shrinkage and cracking during dry seasons.
High clay content distinguishes this soil type, contrasting with aridisols.

Alfisols

More advanced weathering soil, often referred to as "catch-all" soil, prevalent in semi-arid to humid ecosystems.
Moderately leached with high native fertility; generally mildly acidic and features clay accumulation.
Primarily found in temperate humid and subhumid regions, contributing to productive agriculture.

Mollisols

Advanced weathering soils associated with grassland ecosystems.
Distinguished by a thick, dark surface horizon rich in organic matter, often found in prairie regions like the Great Plains in the U.S.
Highly productive agricultural soils, integral to farming practices, even after abandoning agriculture.

Spodosols

Most weathered and highly leached soil type, typically found in cool, wet climates with sandy textures.
Extremely acidic and primarily located in coniferous forests.
Characterized by a light-colored E horizon above a reddish-brown spodic horizon formed in coarse-textured parent material.

Ultisols

Most weathered soil type known for strong leaching and acidity.
Often found in humid temperate and tropical regions, typically located on older, stable landscapes.
Reddish hue due to iron content; characterized by a highly weathered B horizon with relatively low native fertility.

Oxisols

Highly weathered soils found in intertropical regions, marked by a distinguished red color.
Composed of minerals rich in iron and aluminum oxides, resulting in extremely low native fertility.
Characterized by very low nutrient reserves and high phosphorus retention, which limits agricultural usefulness.

Description

Explore the fundamental concepts of soil classification with these flashcards. Learn about different soil orders such as entisols and incepticols, along with their characteristics and formation processes. Perfect for students and enthusiasts of soil science.