C Horizon

Definition

The C horizon is the layer of soil that lies beneath the A (topsoil) and B (subsoil) horizons, composed mainly of weathered parent material. This layer plays a crucial role in soil formation as it serves as the source of mineral content for the upper horizons while also containing larger rock fragments and partially disintegrated materials that have yet to undergo significant soil development.

5 Must Know Facts For Your Next Test

1. The C horizon is critical for the supply of minerals to the overlying soil layers, influencing their fertility and composition.
2. Unlike the A and B horizons, the C horizon is less affected by biological activity, meaning it typically has lower organic matter content.
3. The C horizon can vary significantly in texture, structure, and mineral composition depending on its parent material and the degree of weathering.
4. Understanding the C horizon is essential for activities like agriculture and land management, as it affects drainage and nutrient availability.
5. In some regions, the C horizon may be shallow, while in others it can be quite deep, impacting soil formation processes and local ecosystems.

Review Questions

• How does the C horizon contribute to soil fertility and overall soil health?
  • The C horizon contributes to soil fertility by providing essential minerals to the A and B horizons above it. As water percolates through the soil profile, nutrients from the weathered parent material in the C horizon dissolve and move upward, enriching the upper layers with necessary elements for plant growth. Moreover, this layer’s physical characteristics can influence drainage and aeration in the topsoil, further impacting plant health.
• Compare and contrast the characteristics of the C horizon with those of the A and B horizons in terms of composition and biological activity.
  • The C horizon primarily consists of weathered parent material with larger rock fragments, making it distinct from the A horizon, which is rich in organic matter and supports significant biological activity. In contrast, while the B horizon contains accumulated minerals leached from above and can support some life forms, it still experiences more biological activity than the C horizon. The C layer lacks significant organic material and microbial life, making it less fertile compared to A and B horizons.
• Evaluate the role of the C horizon in influencing soil formation processes over time and its significance in ecological studies.
  • The C horizon plays a vital role in soil formation as it serves as the foundational layer from which other horizons develop through weathering processes. Over time, factors such as climate, vegetation, and topography interact with the C horizon to influence how soils evolve. In ecological studies, understanding the C horizon is important because it helps researchers determine nutrient cycling processes and how soils respond to environmental changes, thereby affecting biodiversity and ecosystem function.

Related terms

Soil Profile: A vertical section of soil that reveals its different layers or horizons, showing the distinct characteristics and composition of each layer.

Parent Material:

The underlying geological material from which soil forms, consisting of weathered rock and mineral matter that contributes to soil's mineral composition.

Horizon: A distinct layer within the soil profile, each with unique physical and chemical properties resulting from various processes like weathering and organic activity.