soil profile
Quick Summary
A soil profile is the vertical sequence of distinct layers, called horizons, that make up a soil. These horizons are formed by the combined actions of living organisms and percolating water.12
The main horizons, from top to bottom, are:
* O horizon: Organic matter on the surface.
* A horizon: Mineral horizon with accumulated humus, mixed with minerals.
* E horizon: A leached layer, lighter in color, depleted of clay and humus.
* B horizon: Subsurface layer where materials from upper layers accumulate, often clay.
* C horizon: Largely unweathered mineral layer, often the parent material.
* R horizon: Consolidated bedrock.
The combined A, E, and B horizons are called the solum, which is the primary zone for soil-forming processes and soil organisms. Soil formation is influenced by parent material, topography, climate, organisms, and time.3456
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