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Crop Science
pages 1-41
23
Agriculture
Undergraduate 3
08/30/2016

Additional Agriculture Flashcards

 


 

Cards

Term
Residual Soils
Definition

-Weathered rock, formed in place

 

- Example:

  • Piedmont (residual soils from igneous rock)
  • Mountain (residual soils from sedimentary rock)
Term
Transported Soils
Definition

-Soils that originate in one place but move around

 

Example: Coastal Plain (marine action)

Term
What are the 2 ways transported soils move by?
Definition
  1. Water - primary method (alluvial soils)
  2. Wind - (loess soils which are windblown deposits)
Term
Each soil has a characteristic set of horizons which develop because of _____________.
Definition
  1. Parent Material
  2. Climate
  3. Topography
Term

 

 

 

Types of horizons in a Georgia soil:

Definition
  • 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
Term

 

Define the 2 main soil properties:

 

  1. Teture
  2. Structure
Definition
  1. Size of particles in soil
  2. Ability of particles to aggregate
Term

 

 

What is a characteristic of soils that have good drainage?

Definition

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

Term

 

 

 

Describe silt

Definition
  • 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
Term

 

 

 

Describe clay

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

 

 

 

What happens as surface area increases?

Definition



Water holding capacity increases because of capillary action and adhesion

Term
As particle size decreases...
Definition

 

...surface area and pore space increase

 

Ex: sand: 1.0m2/gram
 silt: 1 m2/gram

              clay: 10-1,000 m2/gram

Term

 

 

 

Define bulk density

Definition

 

 

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

 

 

Term

 

 

 

What is the formation of aggregates?

Definition

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

 

(collecting together)

Term

 

 

 

What are some factors that promote aggregation?

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

Tillage destroys soil aggregates!

Term

 

 

 

What are the 3 major factors of aggregate stability?

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




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

Definition
Term

 

 

 

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

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

 

 

What are clays?

Definition

 

colloids that can be suspended in solution.

 

Ex: milk is a colloid

Term

 

 

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

Definition

 

Primary Minerals

-course fragments of soils

 

Examples: silica(sand) and feldspar(mica)

Term

 

 

 

Secondary Minerals

Definition

 

Fine particles (clay)

 

Examples: silicate clays, Fe and Al oxides

Term

 

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

 

Name some examples why this is so

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

 

 

What are 2 important concepts regarding soil water?

Definition
  • 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
Term

 

 

 

What are the 2 important concepts regarding soil air?

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

 

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