A horizon
Definition
A horizon is the top layer of soil, rich in organic material and minerals. It is crucial for plant growth due to its high nutrient content and biological activity.
5 Must Know Facts For Your Next Test
- The A horizon is also known as the topsoil.
- It contains a mix of decomposed organic matter called humus.
- The A horizon supports the majority of plant roots.
- This layer is subject to leaching, where water removes soluble substances.
- Soil organisms like earthworms and microbes are abundant in the A horizon.
Review Questions
- What makes the A horizon essential for plant growth?
- How does leaching affect the A horizon?
- Why is biological activity high in the A horizon?
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Study guides (1)
Related terms
B Horizon: Also known as subsoil, it lies beneath the A horizon and accumulates leached materials from above.
C Horizon: The layer beneath B horizon composed mainly of parent material with minimal organic matter.
Humus: Organic component of soil formed by decomposed plant and animal matter, primarily found in the A horizon.
