In soil science, the layer beneath the topsoil is commonly called the subsoil, or which horizon?

In soil science, the layer beneath the topsoil is commonly called the subsoil, or which horizon?

• A. A Horizon
• B. B Horizon
• C. C Horizon
• D. O Horizon

Answer: (B)

In a soil profile, horizons are layers formed with different properties. The topsoil is the A horizon, rich in organic material and roots. Directly beneath that is the B horizon, known as the subsoil. This layer accumulates minerals like clay, iron, and aluminum leached downward from above (illiuvation), so it often has more mineral content, a denser texture, and less organic matter than the topsoil. The O horizon sits on the surface as organic debris, the C horizon is the weathered parent material below, and the R horizon is bedrock. Therefore, the layer beneath the topsoil is the B horizon.

In a soil profile, horizons are layers formed with different properties. The topsoil is the A horizon, rich in organic material and roots. Directly beneath that is the B horizon, known as the subsoil. This layer accumulates minerals like clay, iron, and aluminum leached downward from above (illiuvation), so it often has more mineral content, a denser texture, and less organic matter than the topsoil. The O horizon sits on the surface as organic debris, the C horizon is the weathered parent material below, and the R horizon is bedrock. Therefore, the layer beneath the topsoil is the B horizon.