Soil Formation Factors

• Factors of Soil Formation

Phases of Soil Formation

1. Destructive Phase:

   • Weathering of Rocks and Minerals

     • Disintegration (Physical)

     • Decomposition (Chemical)

2. Constructive Phase:

   • Formation of True Soil

   • Involves soil-forming factors and Pedogenic processes.

Key Equations of Soil Formation

• Dokuchaiev's Equation (1889):
  $S = f(Cl, o, r, p, t)$
  Where:

  • S = Soil formation

  • Cl = Climate

  • o = Organisms

  • r = Relief

  • p = Parent material

  • t = Time

• Jenny's Classification (1941):

  • Divides factors into Active and Passive factors.

Passive Factors

1. Parent Material:

   • Influences soil's nutrient content and weathering intensity.

   • Clay formation favored by high decomposable minerals and less quartz.

2. Relief or Topography:

   • Influences water flow, temperature, soil erosion.

   • Water runoff increases clay content at base of slopes.

   • Distinct soil types at different slope positions.

3. Time:

   • Soil formation is a slow process, determined by many interrelated factors.

   • Factors delaying soil formation include:

     • Cold and dry climate

     • Impermeable parent material

     • High lime content

     • Very steep slopes.

Active Factors

1. Climate:

   • Influences soil with rainfall, temperature, humidity, wind.

   • Different climates yield different soil types (e.g., Lateritic soil in warm, humid climate).

2. Biosphere:

   • Activities of plants and animals impact soil through decomposition and mixing.

   • Vegetation enhances soil water content; burrowing animals mix soil layers.

### Observations

The influence of passive and active factors differs:

• Active Factors: Effects observable in soil development.

• Passive Factors: Control over how climatic and biological elements influence soil without immediate effect.