How are soils categorized?

How are soils categorized?

• A. By color variation within soil
• B. The horizons based on composition and organic matter
• C. The chemical salts present
• D. The depth to bedrock

Answer: (B)

Soils are categorized primarily by the layers that develop in a soil profile through natural soil-forming processes. Each layer, or horizon, has distinct properties—color, texture, structure, organic matter content, and chemistry—that reveal how the soil formed and how it will behave in terms of fertility and drainage. By looking at the sequence and characteristics of these horizons, soils are grouped into types that reflect their formation history and functional behavior. For example, a mineral top layer with organic matter is called the A horizon, a layer where materials have been leached is the E horizon, and a horizon where clays and oxides accumulate is the B horizon; below these is the C horizon of weathered parent material, and, beneath all, bedrock. This horizon-based view captures the key differences among soils more reliably than looking at color variation alone, the presence of chemical salts in isolation, or simply how deep bedrock sits. Those features can inform you about particular properties, but they don’t by themselves define the soil category the way the arrangement and properties of the horizons do.

Soils are categorized primarily by the layers that develop in a soil profile through natural soil-forming processes. Each layer, or horizon, has distinct properties—color, texture, structure, organic matter content, and chemistry—that reveal how the soil formed and how it will behave in terms of fertility and drainage. By looking at the sequence and characteristics of these horizons, soils are grouped into types that reflect their formation history and functional behavior. For example, a mineral top layer with organic matter is called the A horizon, a layer where materials have been leached is the E horizon, and a horizon where clays and oxides accumulate is the B horizon; below these is the C horizon of weathered parent material, and, beneath all, bedrock. This horizon-based view captures the key differences among soils more reliably than looking at color variation alone, the presence of chemical salts in isolation, or simply how deep bedrock sits. Those features can inform you about particular properties, but they don’t by themselves define the soil category the way the arrangement and properties of the horizons do.