What layer of soil typically has the highest concentration of organic material?

The layer of soil that typically has the highest concentration of organic material is the A Horizon. This layer, also known as topsoil, is where organic matter, such as decomposed plant and animal material, accumulates. It is rich in nutrients and is crucial for supporting plant growth. The organic material in the A Horizon contributes to soil fertility, moisture retention, and the overall health of the soil ecosystem.

Conversely, the other layers mentioned have distinct characteristics that differentiate them from the A Horizon. The B Horizon, or subsoil, generally contains minerals and nutrients leached from the topsoil but has less organic material than the A Horizon. The C Horizon is composed of weathered rock and parent material, which lacks significant organic content. The subsoil and C Horizon support the A Horizon but do not contain the same richness in organic matter that makes the A Horizon vital for agricultural and ecological functions.