fv3 - soil composition

AP Environmental Science: Unit 4 – Earth Systems & Resources

Water-Holding Capacity
- Amount of water soil can absorb, influenced by gravity.
- Smaller particles correlate with higher water retention.
- Larger particles allow water to flow to lower layers.
- Organic matter increases water retention by absorbing water.
- Loam: Ideal soil type with equal amounts of small, medium, and large particles.
Particle Sizes and Properties
- Impact characteristics of soil including:
  - Water-holding capacity
  - Porosity
  - Permeability
  - Fertility

Permeability
- Ability of nutrients and water to move through soil horizons.
- Larger particles increase permeability due to more space between them.
Fertility
- Refers to nutrient levels and ability to support vegetation.
- Nutrients include phosphorus and nitrogen, influenced by biomatter.
Chemical Properties
- pH: Measures acidity or basicity; affected by environment and pollutants.
  - Acidic soil often results from pollution and acid rain.
- Cation Exchange: Soil particles attract positively charged ions (cations).
  - Regulates soil pH and nutrient stability.
Physical Properties
- Include aeration, soil compaction, permeability, and particle size.
- Aeration: Ability to take in nutrients, water, and oxygen.
- Soil Compaction: Affects porosity, permeability, and aeration.
  - Heavily compacted soil has limited pore space, reducing nutrient flow.

Biological Properties
- Determined by organisms and plants in the soil.
- Varies by biome or climate.
- Microbial activity and plant root development influenced by soil compaction.
Soil Texture Triangle
- Tool to identify soil types based on clay, silt, and sand percentages.
- Example: 20% clay, 50% sand, 30% silt = loam.

Aeration: Process of increasing oxygen levels in soil.
Cation Exchange Capacity (CEC): Soil's ability to retain and exchange cations.
Fertility: Suitability of soil for supporting plant growth.
Permeability: Ease of fluid flow through soil.
Porosity: Measure of empty space in soil.
Soil Compaction: Pressing together of soil particles, reducing pore space.
Soil pH: Measurement of soil acidity or alkalinity.
Soil Texture Triangle: Graphical tool for classifying soil types.
Water-Holding Capacity: Soil's ability to retain water for plant use.

Understanding soil composition and properties is crucial for environmental science and agriculture.
Key factors include water retention, nutrient availability, and the impact of soil structure on biological