Soils

SOILS: THE FOUNDATION OF ALL LAND
ECOSYSTEMS

• Soils consist of:
• Mineral ~50% sand, silt, clay
• Humus ~5-10% organic matter
• Water ~20-30%
• Air ~20-30%
• Soils vary around the world based on

factors which can be summarized by

• CLORPT

• Cl- Climate (wet, dry, cold, hot)
• O- Organisms (flora, fauna, fungi)
• R- Relief (flat, steep, rolling, mts)
• P- Parent Material (minerals, quartz,

Granitic, Basaltic)

• T- Time (Soils take varying time to

develop 10’s to 1,000s of years)

SOILS LIVE ORGANISMS ARE BROKEN DOWN INTO
DIFFERENT ORDERS (12 MAIN TYPES)

SOILS CONSIST OF STRATIFIED LAYERS CALLED HORIZONS

• Surface Layer
• O Horizon
• A Horizon
• B Horizon
• C Horizon
• R Horizon

SOILS AND HUMAN CIVILIZATION

• Humans have learned to use various

soil types to grow various crop which
produce food at a large scale.

• Mollisols
• Alfisols
• Andisols

Intro to Soils Video