-Weathered rock, formed in place

- Example:

• Piedmont (residual soils from igneous rock)
• Mountain (residual soils from sedimentary rock)

-Soils that originate in one place but move around

Example: Coastal Plain (marine action)

1. Water - primary method (alluvial soils)
2. Wind - (loess soils which are windblown deposits)

1. Parent Material
2. Climate
3. Topography

Types of horizons in a Georgia soil:

• O - organic matter
• A - topsoil, dark organic matter
• B - Zone of illuviation(particles from A deposited to B)
• C - crumbly rocks & newly formed soil
• R - Bedrock

Define the 2 main soil properties:

1. Teture
2. Structure

1. Size of particles in soil
2. Ability of particles to aggregate

What is a characteristic of soils that have good drainage?

Soils that have large amounts of sand/gravel because water moves through more quickly.

BUT - soil water holding capacity is low because large pores won't retain water

Describe silt

• irregular shape, smaller particle
• By itself is a poor soil
• has fine pore spaces which give it good water holding capacity BUT air movement is poor

Describe clay

• regular shape & very fine particles
• Soil pores are very small which makes air & water move through slowly
• contains micropores

What happens as surface area increases?

Water holding capacity increases because of capillary action and adhesion

...surface area and pore space increase

Ex: sand: 1.0m²/gram
 silt: 1 m²/gram

              clay: 10-1,000 m²/gram

Define bulk density

the mass of a unit of dry soil

Example: 

• increased B.D. means little pore space
• decreased B.D. means a lot of pore space
• soils with a lot of sand have less pore space so have higher B.D. Smae with compacted soils

What is the formation of aggregates?

Any action that develops lines of weakness within a soil encourages aggregation

(collecting together)

What are some factors that promote aggregation?

• wetting/drying
• freezing/thawing
• root growth, animal burrowing
• decaying organic matter

Tillage destroys soil aggregates!

What are the 3 major factors of aggregate stability?

• mechanical binding 
  -fungi & bacteria 
   
• temporary cementing
  -gums from microbe exudates 
   
• permanent cementing
  -humus 

Why are we so inefficient at capturing energy? (pg. 16)

What are the 4 major components of soil and how much weight do they take up?

• Minerals - 90-100% 
• Organic Matter - 0-5%
• Water & air - 50%

What are clays?

colloids that can be suspended in solution.

Ex: milk is a colloid

What does not change much as a result of chemical weathering?

Primary Minerals

-course fragments of soils

Examples: silica(sand) and feldspar(mica)

Secondary Minerals

Fine particles (clay)

Examples: silicate clays, Fe and Al oxides

Though organic matter is small in content, it has a large influence on soil properties.

Name some examples why this is so

• makes soil friable (loose and grandular)
• makes soil hold water because it is so absorbent

What are 2 important concepts regarding soil water?

• water held within soil pores may or may not be available to plant
• salts dissolve in soil and those that are in the solution are important for plant nutrition

What are the 2 important concepts regarding soil air?

• soil air is not continuous but is in a maze of pores seperated by soil particles

• compared to atmosphere, soil is high in CO₂ & Humidity and low in O_{2 (because of the low O2, soils with a lot of fine pore space are poorly aerated & roots don't thrive)}