Uscs Soil Classification Chart

David Muir

2 min read

·

10-12-2024

16

0

Share

The United States Department of Agriculture (USDA) Soil Taxonomy is a hierarchical system used to classify soils based on their physical and chemical properties. It's a complex system, but understanding its basics can be invaluable for anyone working in agriculture, environmental science, or land management. This chart provides a simplified overview of the major soil orders, focusing on key characteristics.

Major Soil Orders and Their Characteristics

The USDA Soil Taxonomy uses twelve soil orders as its highest level of classification. Each order represents a broad grouping of soils with similar characteristics. While a full explanation of each would be extensive, this overview highlights key features:

1. Alfisols: These are mineral soils that are relatively high in bases (calcium, magnesium, potassium, sodium). They are typically found in humid and subhumid regions and are often fertile, making them suitable for agriculture. They feature a well-developed horizon.

2. Andisols: These soils are formed from volcanic materials and are rich in organic matter and allophane. They are often found in mountainous regions and are characterized by their dark color and high water-holding capacity. Their high reactivity can make them both beneficial and challenging to manage.

3. Aridisols: These soils are found in arid and semi-arid regions and are characterized by a lack of moisture. They often have a high content of soluble salts and are typically low in organic matter. Irrigation is often necessary for agricultural purposes.

4. Entisols: These are young soils that have not had much time to develop distinct horizons. They are commonly found in areas with recent deposition of sediments, such as floodplains or alluvial fans. Their characteristics vary widely depending on the parent material.

5. Gelisols: These soils are permanently frozen and are found in high-latitude and high-altitude regions. They are characterized by permafrost, which restricts drainage and affects root growth. Climate change significantly impacts these soils.

6. Histosols: These soils are composed primarily of organic matter and are often found in wetlands. They are highly saturated with water and have a low bulk density. They are often used for peat extraction or wildlife habitat.

7. Inceptisols: These are soils that show some development of horizons but are less developed than Alfisols or Ultisols. They represent an intermediate stage of soil formation. They are widespread and exhibit considerable diversity.

8. Mollisols: These are dark, fertile soils that are rich in organic matter. They are typically found in temperate grasslands and are highly suitable for agriculture. They are known for their high nutrient content.

9. Oxisols: These are highly weathered soils that are low in bases and nutrients. They are typically found in tropical and subtropical regions and are often characterized by a high content of iron and aluminum oxides. Their fertility is often limited.

10. Spodosols: These soils are characterized by the accumulation of organic matter and iron and aluminum oxides in a subsurface horizon. They are typically found in cool, humid regions under coniferous forests. Their acidic nature influences vegetation.

11. Ultisols: These are highly weathered soils that are low in bases and are typically found in humid and subhumid regions. They are often acidic and have a high content of clay. Their low fertility requires management strategies.

12. Vertisols: These soils are characterized by high clay content, which causes them to shrink and swell with changes in moisture content. They are typically found in semi-arid and subhumid regions. Their cracking behavior impacts land use.

This is a simplified overview. The USDA Soil Taxonomy is incredibly detailed, with further subdivisions within each order. Consult detailed resources for in-depth information and specific soil classifications. Understanding soil types is crucial for effective land management and agricultural practices.