1. Layers of soil (soil horizons) soil profile
Surface litter – fallen leaves and partially decomposed organic matter
Topsoil – organic matter, living organisms, and rock particles
Zone of leaching - dissolved or suspending materials moving downward, minerals may leach quickly and deprive plants of nutrients
Subsoil – larger rock particles with organic matter, and inorganic compounds
Weathered parent material – rock that has undergone weathering
Bedrock – solid rock layer

2. Topsoil is richer in organic matter than the other soil layers; without it plants cannot grow
Particle size increases down

3. Soil Characteristics Color Texture
Darker soils means richer in humus and nutrients
Use as indicator of soil’s fertility
Texture
Based on particle size
Clay, silt, and sand (smallest to largest)
Loam – even mixture of the 3 particle sizes
Influences workability because of how porous it is
Finer the particle size, less space and harder for air and water to travel through
Silty soil or loamy material is best for plant growth

4. Soil Characteristics (continued)
Structure
Arrangement of particles – “clumpiness”
Clumpy soil has more humus and is more rich in nutrients
Too clumpy may prevent plant roots from growing pH
Plants die if soil is too acidic or too alkaline
Acid precipitation and leaching can affect pH

5. Learning Target
To understand ways to prevent soil degradation and why they will prevent soil degradation

6. Land degradation occurs when human activity or
natural processes damage land so that it can no
longer support plant growth or other ecosystem
services

7. Erosion #1 cause of land degradation
Can help create soil through deposition
Takes away the topsoil
Humans cause this through overgrazing, clearing forests on slopes, clear-cutting, and leaving soil bare after harvests

8. Farming Practices for Soil Conservation
Plants slow wind and water
roots hold soil in place and absorb water
Intercropping
Crop rotation
Cover crops
Shelterbelts
Conservation tillage
Terracing
Contour farming
soil conservation

9. Intercropping Planting crops in mixed arrangements More plant cover
Less vulnerable to insects and disease

10. Crop rotation Alternate crops grown in a field
Returns nutrients to soil
Breaks disease and pest
cycles
Prevents erosion