Soil Science and Health Principles

Major Land Resource Areas (MLRAs)

• Defined as distinct geographic areas characterized by specific natural resources.
• Major MLRAs identified include:
  • Blue Ridge
  • Piedmont
  • Sandhills
  • Inner Coastal Plain
  • Outer Coastal Plain
  • Coastal Zones

Soil Orders

• There are 12 soil orders recognized.
• The most common soil orders in South Carolina (SC) include:
  • Ultisols
  • Entisols
  • Inceptisols
  • Alfisols

Soil Forming Factors

• Soil formation depends on five key factors:
  1. Climate
  • Influences chemical reactions in the soil, affecting properties like fertility.
  1. Organisms
  2. Relief (topography)
  3. Parent material
  4. Time
• Importance of these factors:
  • Determines soil characteristics: fertility, structure, and ability to support plant life.
  • Vital for agriculture, land management, and environmental protection.

Soil Health Principles

• Soil Health is defined as the ability of soil to function as a living ecosystem beneficial for plants, animals, and humans.
• Key principles for maintaining soil health:
  1. Soil Armor
  2. Minimizing Soil Disturbance
  3. Plant Diversity/Continual Live Plant Cover
  4. Livestock Integration

Soil Texture

• Refers to the proportion of three particle sizes in mineral soil:
  1. Sand (largest particles)
  • Size: 2.00 to 0.05 mm
  • Characteristics: Low chemical activity, large pore space, low water holding capacity, high conductivity, and gritty texture.
  1. Silt
  • Size: 0.05 to 0.002 mm
  • Characteristics: Low chemical activity, medium pore space, better water holding capacity, smooth and powdery texture.
  1. Clay (smallest particles)
  • Size: < 0.002 mm
  • Characteristics: High chemical activity, high nutrient and water holding capacity, small pore space, low conductivity, sticky and plastic properties.
  • A gram of clay can have a surface area comparable to the size of a football field.

Munsell Color Book

• A universal standard for soil color representation through notation.
• Composition of Munsell Notation:
  • Identifies hue (dominant color) with letter symbols (e.g., Y for yellow, R for red).
  • The value: Lightness of color; scale from 0 (pure black) to 8 (pure white).
  • The chroma: Intensity of color; rated from 1 (less intense) to 8 (most intense).
• Infer soil characteristics through color, including drainage class, organic matter content, and soil origin.

Soil Color Importance

• Soil color is the most easily observable soil property and helps distinguish different soil horizons.
• Influencing factors:
  • Organic Matter Content: Higher levels lead to darker soils.
  • Oxidation/Reduction State: Presence of iron influences color (orange, red, yellow, brown) while its absence leads to greys.

Soil Resource Concerns

Erosion

• Types of erosion:
  1. Non-Concentrated Water Erosion: Minor streams causing erosion if untreated.
  2. Wind Erosion: Dust and soil particles transported by wind.
  3. Concentrated Water Erosion: Focused water flow leading to soil loss.
  4. Coastal Erosion: Erosion along shorelines.
• Coastal Compaction: Caused by machinery or animals, compressing soil particles and reducing pore space.

Soil Horizons

• Soil layers vary in composition and characteristics:
  • O Horizon: Organic organisms (like decaying leaves).
  • A Horizon: Topsoil, rich in minerals and organic matter, supports biodiversity.
  • E Horizon: Leached of nutrients (clay, minerals).
  • B Horizon: Subsoil rich in minerals leached from above layers.
  • C Horizon: Parent material from which soil develops.
  • R Horizon: Bedrock.

Soil Structure

• Influences water movement through soil:
  • Well-Structured Soils: Facilitate infiltration and percolation (e.g., granular, prismatic).
  • Poorly Structured Soils: Can impede water movement (e.g., platy structure).
  • Compacted Soils: Limit water infiltration and movement.
• Soil texture impacts:
  • Sandy soils: High infiltration and rapid drainage, low storage.
  • Clay soils: Limited infiltration, but high water holding capacity.
• Movement mechanisms include capillary action and gravity.
• Good soil structure is crucial for plant growth, ensuring water and air availability to roots.