Soil Formation and Development

Introduction
Soil Formation: Breakdown of rocks through weathering.

Rocks and Minerals
Definition of Rock: Solid mineral material forming Earth's surface.
Types of Rocks:
Igneous Rocks: Formed from molten magma (e.g., granite, basalt).
Sedimentary Rocks: Accumulated rock fragments (e.g., limestone, shale).
Metamorphic Rocks: Altered by heat and pressure (e.g., marble, slate).
Minerals: Naturally occurring inorganic substances.
Primary Minerals: Quartz, feldspar, mica.
Secondary Minerals: Clay minerals, iron oxides.

Weathering Processes
Physical Weathering: Breakdown without chemical changes.
Examples: Freeze/thaw cycles, biological activity, exfoliation.
Chemical Weathering: Chemical alteration of minerals.
Examples: Hydrolysis, dissolution, oxidation.

Factors Influencing Soil Formation (CLORPT)
Climate (C):
Precipitation and temperature affect weathering and organic matter decomposition.
Higher temperatures accelerate chemical reactions; cold climates enhance physical weathering.
Organisms (O):
Vegetation and soil organisms contribute organic matter and mix soil, enhancing fertility and structure.
Relief/Topography (R):
Shape and slope of land affect drainage, erosion, and sun exposure.
Steeper slopes have thinner soils due to erosion; flatter areas accumulate more soil.
Parent Material (P):
Geological or organic precursors of soil determine initial properties.
Inorganic (e.g., rocks) and organic materials (e.g., plant/animal remains).
Time (T):
Duration of soil formation affects soil maturity.
Younger soils have less horizon development; older soils are more developed.

Soil Sequences
Catenas: Soils differing primarily due to relief and drainage variations.
Chronosequence: Soils differing due to the time elapsed since formation.
Lithosequence: Soils differing due to variations in parent material.
Climosequence: Soils differing due to changes in climate.
Biosequence: Soils differing due to biological factors.

Basic Processes in Soil Formation
Transformation: Chemical and physical changes of soil constituents.
Translocation: Movement of materials within soil horizons.
Additions: Inputs from external sources, such as organic material.
Losses: Removal of materials from the soil system.