Which soil horizon is typically rich in organic material and surface litter?

The O horizon is characterized by a significant accumulation of organic material, including decomposed leaves, plant material, and other organic debris. This layer is typically found at the surface of forested and grassland ecosystems and is often rich in nutrients and microorganisms that aid in the decomposition process. The presence of this organic matter plays a crucial role in soil fertility, moisture retention, and the support of a diverse ecosystem.

In contrast, the A horizon, while also containing organic material and being crucial for plant growth, primarily consists of mineral soils mixed with some organic matter but is not as rich in pure organic content as the O horizon. The B horizon refers to the subsoil and is where leaching occurs, leading to the accumulation of minerals and nutrients but little organic matter. The C horizon consists of weathered parent material and lacks the characteristics associated with organic richness. Understanding the distinct features of these horizons helps in recognizing their roles in soil health and ecology.