Exam 1 Flashcards
What does soil provide as a plant growth media?
- nutrients
- water
- physical support
- oxygen
- temperature buffer
Name 6 roles or services that soil provide?
- Media for plant growth
- Recycling system for nutrients and waste
- Water supply and purification
- Habitat for soil microorganisms
- Engineering media (build things)
- Climate modification
What is a macro nutrient? Name the 6 essential elements?
Nutrients needed in large quantities •nitrogen (n) •phosphorous (p) •potassium (k) •calcium (ca) •Magnesium (mg) •sulfur (s)
What is a micro nutrient? Name 6?
Nutrients needed in small quantities/ needed in only specific plants. •Boron (b) •Copper (cu) •Iron (fe) •Manganese (mn) •Molybdenum (mo) •zinc (zn) Maybe-chlorine, cobalt Some-sodium,vanadium,chromium
How does soil influence climate?
- carbon sequestration(holds carbon)
- evaporation ie clouds
- particulate matter(dust prevent sun)
What is the soils role in the ecology of the plant?
Soil is the interface between
- biosphere
- hydrosphere (water)
- lithosphere (not alive)
- atmosphere (air)
What is the difference between soil an soils?
Soil is 4 components
-mineral, water, air, biomass (living and previously living)
Soils is the soil and the rest of everything on the planet
Describe the oversimplified process for the formation of soil.
- Rock exposed at earths surface is degraded.
- Creates a rubble = regolith
- Particles tend to move (water and rain)
- Regolith is further modified by living organisms
- Eventually “soil” is created.
Define “soil profile”?
Verticals section of the soil.
Name the 3 primary soil horizons?
A horizon- top soil
B horizon- in general lighter in color
C horizon- almost rock
What is a plow layer?
Is various layers of soil mixed together as a result of plowing
Why is the soil near bedrock less developed than near the surface?
**Less weathering and chemical reactions taking place
How might lower horizons be modified?
**Chemical reactions and large root systems
Name the constitutes and %
Inorganic particles (45%) Organic particles (5%) Air/ water (50%) controlled by climate
Define soil texture?
The relative quantities of 3 particle sizes
What is sand silt and clay?
Sand- large particle sizes (2mm-.05)
Silt - less than (.05mm-.002)
Clay- less than (.002)
How does one determine a texture class?
Use a textural triangle
Texture classifications determine what?
Water holding capacity
Nutrient holding capacity
Tilth- the farmability of the soil(ease of plowing)
Engineering properties
Define soil structure?
General arrangement of particles
What can cause soil aggregation?
(Aggregation is the tendency for particles to stick together,)
•Caused by (plowing) infrequent disordering of particles
•root activity, worms, decaying organic matter microorganisms
What is organic mater? Humus?
Compounds made with carbon chains. Ie plants animals and microorganisms ( must be dead and mainly decomposed by microbes)
Humus is om that has formerly been decayed
What is a soil solution?
Is soil water…water+ salts+ elements+ particles+ chemicals.
How does soil air differ from atmospheric air?
In general higher co2 and lower o2 than atmospher
Indicate the 3 ways in which nutrients moves from the soil into the plant?
- Root interception (must touch)
- Mass flow (water pulled up from leaves…responsible for must nutrient absorption except p,k,zn
- Diffusion way for p,k,zn absorption
What is the relative importance of root growth and interception of nutrient uptake?
Insignificant
Discuss why soils are considered to be reusable but not renewable?
One can use it over and over but you can’t make more of it
Within a particular climate, what is the primary factor that determines the spread of weathering?
The nature and composition of the rock
What are the three primary rock types?
Igneous
Metamorphic
Sedimentary
Name 3 agents of physical weathering?
Temperature change
Abrasion- (water ice water flow and wind)
Plants and animals
What might cause chemical weathering?
Organic/ inorganic acids
Ph changes
Oxidation
Hdrilices
Indicate the 5 factors involved in the formation of soils?
A. Parent material- rock B. climate C. Biota D. Topography E. Time
How might parent material influence the nature of the resulting soil?
Composition determines what meme rails are released
Soil texture will be determined by rock type
Composition determines initial soil acidity level
How is parent material classified? And possible origins of parent material?
Based on its origin -residual rock -water transported Gravity transported Wind deposited Ice transported Organic deposits (Pete bogs)
What is climates role in soil formation?
Acts on parent material
What is effective precipitation in regards to soil?
Pen iteration to regolith
How does temperature affect soil formation?
Freezing and thawing and effects chemical reactions
What aspects of vegetation affect the formation of soils? What about animals?
Vegetation -root systems -Residual competition (pine needles) -Microclimates Other organisms -tunnels (moles) -megafauna (big animals compact)
Why are soils on steep slips thin?
Because soil is dispersed down hill
Detail the typical progression of soil formation?
.
Name and describe the four processes that affect soil formation?
- transformations- physical and/or chemical changes the soil structure
- translocations (movement)
- additions
- losses (erosion, leaching)
Explain why soils are so different from each other?
Because the 5factors are different everywhere
Name the 6 master horizons and layers and indicate characteristics?
O-typically formed above mineral layer, derived from organic material and subdivided based on decomposition.
A-top most mineral layer (top soil) contains organic matter
E- eluviation (things flowing in and out) common in forests
B-undergone few transformations
C- least effected by weathering
Bedrock layer
Why might horizons be sub-divided?
Because there are distinct layers within those horizons
How are created soils signified in soil surveys?
With a caret (^)
Name the 2 primary soil types in ky?how are they similar?
Ultisol- south east- low fertility
Alfisol- western-
Both are highly weathered and usually develop under forests. Both are highly leached due to high rain fall and both ate acidic
