pedogenic process

The pedogenic process refers to the sequence of physical, chemical, and biological processes that lead to the formation and development of soil. These processes act on parent material (rock or sediment) over time to produce distinct soil horizons (layers). The main stages of pedogenesis include:

1. Weathering of Parent Material:

Physical and chemical breakdown of rocks into smaller particles. This forms the mineral base of the soil.

2. Organic Matter Accumulation:

Plants and animals contribute organic material. Microorganisms decompose this material into humus, enriching the topsoil.

3. Leaching (Eluviation):

Water percolates through soil, dissolving and carrying away minerals and nutrients from upper horizons.

4. Accumulation (Illuviation):

Minerals and organic matter from upper layers are deposited in lower layers, forming distinct horizons rich in clay, iron, or organic compounds.

5. Clay Formation:

Secondary minerals such as clays form through weathering and contribute to soil structure.

6. Oxidation and Reduction:

Changes in redox conditions (due to water saturation or aeration) alter soil color and chemistry, particularly involving iron and manganese.

7. Soil Horizon Development:

Over time, these processes create layers:

O Horizon (organic matter)

A Horizon (topsoil)

E Horizon (leached zone, if present)

B Horizon (subsoil accumulation)

C Horizon (weathered parent material)

R Horizon (bedrock)

The type and intensity of these processes depend on climate, organisms, relief, parent material, and time—known as the five soil-forming factors.

~NGA AgroClimate Tech