1. A soil profile is an exposure from the surface downward through a soil to its parent material.
Image: Martin Miller
Image: NRCS
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2. Soil profiles generally expose three layers or soil horizons.
Image: National Cooperative Soil Survey
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3. The upper “A” horizon contains organic matter mixed with mineral particles. Percolating water dissolves and removes some mineral constituents from the “A” horizon.
Horizon “A”
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4. Some constituents dissolved from the “A” horizon are deposited below in the “B” horizon.
Horizon “B”
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5. The “C” horizon is the lower soil layer developed on the underlying parent material.
Horizon “A”
Horizon “B”
Horizon “C”
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6. A mature soil profile with well developed A, B, and C horizons takes hundreds to thousands of years to develop.
Horizon “A”
Horizon “B”
Horizon “C”
Image: NRCS
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