What is meant by the term "soil horizon"?

• A. A layer of soil with uniform properties
• B. A distinct layer of soil varying in composition
• C. A collection of soil types in a region
• D. A type of vegetation growing in the soil

Answer: (B)

The term "soil horizon" refers to a distinct layer of soil that has unique characteristics, including differences in composition, color, texture, and structure from the layers above and below it. Each soil horizon encompasses varying physical and chemical properties, which are influenced by factors such as the accumulation of organic matter, the leaching of minerals, and climatic conditions. This layered structure is critical for understanding soil formation and function, as it reflects the soil's history and its ability to support plant life.

In contrast to other options, a uniform layer of soil does not represent the variability typically found in a soil horizon, and a collection of soil types pertains to a broader context rather than focusing on specific layers. Additionally, vegetation, while an important aspect of the soil ecosystem, does not define the soil horizon itself, as it refers to the biological life interacting with the soil rather than the soil's physical composition and stratification.