5.2 Soil

Regolith

• The layer of rock and mineral fragments that nearly everywhere covers Earth’s surface

Soil

• A combination of mineral and organic matter, water, and air.

Soil Horizon

• A layer of soil that has identifiable characteristics produced by chemical weathering and other soil-forming processes

Soil Profile

• A vertical section through a soil showing its succession of horizons and the underlying parent material.

Pedalfer

• Soil of humid regions characterized by the accumulation of iron oxides and aluminum- rich clays in the B horizons.

pedocal

• Soil associated with drier regions and characterized by an accumulation of calcium carbonate in the upper horizons

laterite

• A red, highly leached soil type found in the tropics that is rich in oxides of iron and aluminum.

Key Concept

• Soil is the part of the regolith that supports the growth of plants

Key Concept

• Soil has four major components: mineral matter, or broken-down rock; organic matter, or humus, which is the decayed remains of organisms; water; and air.

Key Concept

• The most important factors in soil formation are parent material, time, climate, and slope.

Key Concept

• Soil varies in composition, texture, structure, and color at different depths.

Key Concept

• Three common types of soil are pedalfer, pedocal, and laterite.

Key Concept

• However, human activities that remove natural vegetation, such as farming, logging, and construction, have greatly accelerated erosion.