L17_urban soils

## Urban Soil Overview
- **Urban Soil Mosaic**: Consists of various soil types, including managed, transported, disturbed, and remnant soils.

## Role of Soil
- **Support**: Acts as a growth medium for roots.
- **Water**: Retains moisture necessary for plant survival.
- **Aeration**: Provides necessary oxygen (O2) for root respiration.
- **Nutrients**: Supplies essential nutrients to plants.

## Volumetric Composition of Soil
- **Typical Volumetric Composition**:
- Water: 20-30%
- Air: 20-30%
- Organic Matter: 5%
- Mineral: 45%

## Soil Properties
- **Structure**: Arrangement of soil particles and their aggregation.
- **Texture**: Composition and size of soil particles.
- **Other Properties**: pH, density, organic matter, and nutrients.

## Soil Structure
- **Definition**: Grouping/arrangement of soil particles into aggregates.
- **Influences**: Root penetration, water movement, aeration.
- **Creation**: Biotic activities, root growth, freeze/thaw cycles.
- **Changeability**: Soil structure can be altered.

### Soil Structure Types
- **Single Grain**: Rapid water/gas movement.
- **Blocky**: Moderate water/gas movement.
- **Granular**: Moderate movement.
- **Prismatic**: Rapid water/gas movement.
- **Platy**: Slow movement.
- **Massive**: Slow movement.

## Urban Soil Alterations
- **Impact of Urban Systems**: Changes in structure may affect root development and water retention, impacting overall ecosystem health.

## Soil Texture
- **Definition**: Relative proportions of sand, silt, and clay.
- **USDA Classifications**:
- Sand: 0.05 – 2.0 mm
- Silt: 0.002 - 0.05 mm
- Clay: