Soil Composition and Properties

Soil Composition

• Soil is composed of:
  • Mineral particles (45%): sand, silt, clay
  • Organic matter (5%): decomposed plant and animal residues
  • Water (25%): varying amounts of water depending on soil type and conditions
  • Air (25%): pore spaces between particles that contain air
• Soil texture: determined by the proportion of sand, silt, and clay particles
  • Sand: large particles, drains well, low water-holding capacity
  • Silt: medium particles, moderate drainage, moderate water-holding capacity
  • Clay: small particles, poor drainage, high water-holding capacity

Soil Types

• Major soil types:
  1. Clay soils:
     • High clay content, poor drainage, often sticky when wet
     • Example: clay loam, heavy clay
  2. Sandy soils:
     • High sand content, good drainage, often dry and coarse
     • Example: sandy loam, beach sand
  3. Silty soils:
     • High silt content, moderate drainage, often fertile
     • Example: silt loam, loamy silt
  4. Loamy soils:
     • Balanced mix of clay, silt, and sand, well-draining, fertile
     • Example: clay loam, silt loam, sandy loam
• Other soil types:
  • Peat soils: high organic matter content, acidic, often wet
  • Chalky soils: high calcium carbonate content, alkaline, often dry
  • Saline soils: high salt content, often found in coastal areas
  • Podzolic soils: acidic, high organic matter, often found in coniferous forests

Soil Composition

• Soil consists of four main components:
• Mineral particles (45%) - sand, silt, clay
• Organic matter (5%) - decomposed plant and animal residues
• Water (25%) - varying amounts depending on soil type and conditions
• Air (25%) - pore spaces between particles containing air

Soil Texture

• Soil texture is determined by the proportion of:
• Sand - large particles, good drainage, low water-holding capacity
• Silt - medium particles, moderate drainage, moderate water-holding capacity
• Clay - small particles, poor drainage, high water-holding capacity

Soil Types

Major Soil Types

• Clay soils:
• High clay content
• Poor drainage
• Often sticky when wet
• Examples: clay loam, heavy clay
• Sandy soils:
• High sand content
• Good drainage
• Often dry and coarse
• Examples: sandy loam, beach sand
• Silty soils:
• High silt content
• Moderate drainage
• Often fertile
• Examples: silt loam, loamy silt
• Loamy soils:
• Balanced mix of clay, silt, and sand
• Well-draining
• Fertile
• Examples: clay loam, silt loam, sandy loam

Other Soil Types

• Peat soils:
• High organic matter content
• Acidic
• Often wet
• Chalky soils:
• High calcium carbonate content
• Alkaline
• Often dry
• Saline soils:
• High salt content
• Often found in coastal areas
• Podzolic soils:
• Acidic
• High organic matter
• Often found in coniferous forests

This quiz covers the composition of soil, including mineral particles, organic matter, water, and air, as well as soil texture and its characteristics. Test your knowledge of sand, silt, and clay particles and their effects on soil properties.