Soil-forming Processes

Soils form via four major processes: addition, loss, transformation, and leaching.

Learning Goals

• Learn the four processes by which soils develop.

Acknowledgment

The list of soil-forming processes is lifted near-verbatim from Prof. Phil Larson’s Physical Geography course.

Soil-forming processes

Soils form through the following set of processes:

• Addition
  • Organic matter accumulation: Things die on the surface (plants, animals) and below the surface (plant roots, burrowing animals)
  • Inorganic matter accumulation
    • Dust
    • Regolith production
    • Sediment deposition
• Loss
  • Erosion – stripping of organic and mineral content from the surface (e.g., by wind, water, ice)
  • Dissolution – removal of minerals within the soil in solution
• Transformation
  • Decomposition of primary minerals into secondary minerals
  • Translocation (movement of material within soils)
• Leaching = movement of dissolved matter via groundwater in a soil. May move it within the soil or carry dissolved matter out of the soil completely.
  • Leaching from upper soil units into deeper soil units (can carry materials down via water that changes pH, gas content, and redox as the water evaporates).
  • Leaching from parent material or organic matter.

Video

Jerry Delsol again has a great introduction, here to these soil-forming factors:

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