Final answer:
A soil profile comprises several horizons labeled as O, A, B, and C. The O horizon contains organic matter, while the A horizon is the nutrient-rich topsoil. The B horizon, or subsoil, houses fine materials that have traveled downwards, and the C horizon includes the broken-down parent material, forming the soil base.
Step-by-step explanation:
Understanding the Soil Profile
When aiming to draw and label a soil profile, we must identify and understand the different horizons that exist within it. A soil profile is a vertical section of the soil that showcases various layers, each with distinct properties and composition. These layers, known as horizons, are typically labeled as O, A, B, and C.
The O horizon is on the surface and is composed of organic matter including decomposed vegetation, commonly known as humus, which enriches the soil with nutrients. Just beneath that is the A horizon, which some call the topsoil. It consists of a mixture of organic material with inorganic products of weathering and is the most productive for plant life due to its rich organic content. Below the A horizon is the B horizon or subsoil, which accumulates fine materials that have moved down from the above layers, often forming a dense layer in the soil profile. The final layer is the C horizon, also known as the soil base, which includes the parent material along with the organic and inorganic matter broken down to form soil. Below the C horizon lies the bedrock, which is not part of the soil profile.
Some soils may have additional layers or lack one of the typical horizons. The thickness of the layers varies and depends on factors that influence soil formation, such as climate, topography, and biological activity. Understanding these layers helps soil scientists analyze the soil's past and make recommendations for its future use.