What is Pedogenesis or Pedogenic Processes

Pedogenesis (also known as the pedogenic process) is the natural process of soil formation from parent material through physical, chemical, biological, and environmental interactions over time. It leads to the development of distinct soil horizons (layers).

Main Pedogenic Processes:

1. Weathering of Parent Material

-Physical weathering: Breaks rocks into smaller particles through temperature changes, freeze-thaw cycles, root pressure, etc.
-Chemical weathering: Alters the mineral composition via reactions like hydrolysis, oxidation, carbonation.
-Biological weathering: Roots, microorganisms, and organisms contribute to breakdown.

2. Horizon Formation
Soil develops into layers known as:

-O Horizon: Organic layer (not always present)
-A Horizon (Topsoil): Rich in organic matter, site of intense biological activity
-E Horizon: Zone of eluviation (leaching of silicate clay, iron, or aluminum)
-B Horizon (Subsoil): Zone of illuviation (accumulation of materials from upper layers)
-C Horizon: Weathered parent material
-R Horizon: Unweathered bedrock

3. Organic Matter Accumulation
Plants and animals die and decompose, enriching upper layers with humus, enhancing fertility.

4. Leaching (Eluviation)
Water percolates down, carrying dissolved minerals and particles (especially clay, iron, aluminum) from upper horizons.

5. Deposition (Illuviation)
These materials accumulate in lower horizons, especially the B horizon, changing its structure and chemistry.

6. Soil Profile Development
Over time, the soil exhibits a vertical profile with distinct horizons that reflect the intensity and type of processes acting on them.

Factors Influencing Pedogenesis:
-Climate (temperature and precipitation)
-Organisms (plants, animals, microbes)
-Relief (topography and drainage)
-Parent material (original rock/mineral base)
-Time (long-term process)

Together, these factors (often summarized as CLORPT) determine the rate and characteristics of soil development.

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