CRSS 4540 Pedology (After exam 2 to
final) With Complete Updated Solution 2024.
Five factors of soil formation
S = f(climate, organisms, relief, parent material, time)
Alternative factors of soil formation
s = f(s, c, o, r, p, a, n)
s = other soil properties
c = climate
o = organisms
r = relief
p = parent material
a = age of the surface
n = spatial location (things closer to each other are most likely to be similar than
compared to those farther away)
Climate soil formation
-solar radiation
-temperature
-precipitation
-water is driving force for soil formation
-effects driven by intensity of leaching and amount of biomass production
-as precip increases, pH decreases, depth to carbonates increases, N content
increases, clay content increases.
How rainfall affects weathering/ leaching
- <20"/yr is low
-20-30"/yr clays are stable ( cation leaching low)
-40-50"/yr 1:1 Kaolinite is favored due to loss of basic cations (2:1s may persist)
-70-100"/yr Intense weathering and leaching (Fe oxides accumulate)
climate types
-polar climates - freeze thaw cycles produce ice wedges and frost heaving in polar
climates
-cold temps - no Bt in Antarctica due to slow weathering reactions
-Temp influences the type and quantity of vegetation in an area
- P - ET = Peffec controls amount of water available to drivesoil formation and the depth
to which leaching occurs
Moisture regimes soil
Aridic - desert (Aridisols)
Ustic - grassland (Mollisols)
Ustic - some tree cover (Alfisols)
, Aquic -
Water Balance Examples
Recharge
Surplus water = leaching
Vegetation EVpTRprition = Deficit
Organisms soil formation
soil development
-under grasslands they are thick dark horizons THICK A
-under hardwoods have thinner A horizons
-
Relief
Physical configuration of the land surface with respect to the relative elevation and
slope
catena
A group of soils that commonly occur together in a landscape, each characterized by a
different slope position and resulting set of drainage-related properties.
hillslope to valley
Slope shape
Convex slopes lose water; concave slopes accumulate water
Convex positions
have MORE runoff and erosion than planar or concave positions
more runoff =
less water infiltration = less soil development
Enhanced erosion
removes surficial soil and slows development
Concave positions
ACCUMULATE water and sediment
-Overthickened A and E horizons
-Thick A horizons due to slow O.M decomposition
Shallow subsurface flow
may carry mobile constituents to lower topographic positions
Lower Coastal Plain
(red area is oxidized)
Interfluve -> Slope -> Floodplain -> Stream
Appalachian and Valley and Ridge
Sandstone and Limestone aquifers
Blue ridge/ Piedmont
Crystalline rock aquifers
Coastal Plain
Sand aquifers
Limestone aquifers
Major soils of Piedmont to Coastal Plain
final) With Complete Updated Solution 2024.
Five factors of soil formation
S = f(climate, organisms, relief, parent material, time)
Alternative factors of soil formation
s = f(s, c, o, r, p, a, n)
s = other soil properties
c = climate
o = organisms
r = relief
p = parent material
a = age of the surface
n = spatial location (things closer to each other are most likely to be similar than
compared to those farther away)
Climate soil formation
-solar radiation
-temperature
-precipitation
-water is driving force for soil formation
-effects driven by intensity of leaching and amount of biomass production
-as precip increases, pH decreases, depth to carbonates increases, N content
increases, clay content increases.
How rainfall affects weathering/ leaching
- <20"/yr is low
-20-30"/yr clays are stable ( cation leaching low)
-40-50"/yr 1:1 Kaolinite is favored due to loss of basic cations (2:1s may persist)
-70-100"/yr Intense weathering and leaching (Fe oxides accumulate)
climate types
-polar climates - freeze thaw cycles produce ice wedges and frost heaving in polar
climates
-cold temps - no Bt in Antarctica due to slow weathering reactions
-Temp influences the type and quantity of vegetation in an area
- P - ET = Peffec controls amount of water available to drivesoil formation and the depth
to which leaching occurs
Moisture regimes soil
Aridic - desert (Aridisols)
Ustic - grassland (Mollisols)
Ustic - some tree cover (Alfisols)
, Aquic -
Water Balance Examples
Recharge
Surplus water = leaching
Vegetation EVpTRprition = Deficit
Organisms soil formation
soil development
-under grasslands they are thick dark horizons THICK A
-under hardwoods have thinner A horizons
-
Relief
Physical configuration of the land surface with respect to the relative elevation and
slope
catena
A group of soils that commonly occur together in a landscape, each characterized by a
different slope position and resulting set of drainage-related properties.
hillslope to valley
Slope shape
Convex slopes lose water; concave slopes accumulate water
Convex positions
have MORE runoff and erosion than planar or concave positions
more runoff =
less water infiltration = less soil development
Enhanced erosion
removes surficial soil and slows development
Concave positions
ACCUMULATE water and sediment
-Overthickened A and E horizons
-Thick A horizons due to slow O.M decomposition
Shallow subsurface flow
may carry mobile constituents to lower topographic positions
Lower Coastal Plain
(red area is oxidized)
Interfluve -> Slope -> Floodplain -> Stream
Appalachian and Valley and Ridge
Sandstone and Limestone aquifers
Blue ridge/ Piedmont
Crystalline rock aquifers
Coastal Plain
Sand aquifers
Limestone aquifers
Major soils of Piedmont to Coastal Plain
