Exam 1 Flashcards
What are the 2 scales of soil?
- Global
- Local
Global scale of soil
- soil is at the intersection of atmosphere, lithosphere, and hydrosphere
- Soil is a biogeochemical membrane
Critical zone
-comprised of the outer layers of the planet that lie between the tops of the tallest trees and the bottom of the groundwater aquifers that feed out rivers.
Local scale of soil (for ideal soil system)
- 4 phase system
- 20-30% air
- 20-30% water
- 5% organic
- 45% mineral
- pore space is air, water, organic
- soil solids are minerals
Ecosystem services of soil
- provisioning services (food, drinking water, fuel)
- Regulating services (climate, water, disease)
- Supporting services (soil formation, nutrient cycling)
- Cultural services (educational, recreational, tourism)
What forces move particles?
Ice, wind, water
MASTER horizons
- O (organic horizons)
- A, B, C, E (mineral horizons)
- R (bedrock horizon)
Organic vs mineral soil
-organic has >20% carbon
Oi (stage 1)
–litters
Oe (O2)
-partially decomposed
Oa (O2)
- highly decomposed by microbiota
- AKA humus
A (A1)
-mixture of humified organic matter and mineral soil (topsoil)
E (A2)
- eluviated leached horizon
- leached by water
B (B2)
- altered, undergoing change
- Illuviation
- Loss of carbonates
- Change in color or structure
R
-weathered bedrock
What is the regolith composed of?
-Everything above the bedrock
What is the solum composed of?
-A and B layer collectively
p
-plow layer, abrupt smooth boundary
t
-illuvial accumulation of silicate clays
w
-distinctive color or structure
g
-gleying (strong grey color)
s
-illuvial accumulation of sesquioxides
h
-illuvial accumulation of organic matter
d
-dense, impermeable (gegenic)
x
- dense, brittle, impermeable (genetic)
- Bx
Topsoil
-composed of organic horizons and the A horizon
subsoil
-composed of B and C horizons
Catena
- soils that commonly occur in the landscape in sequence
- Each member of the catena has similar age, and parent material, but different drainage classes.
What is the point of reference for profile depth?
-top mineral soil horizon
Very poorly drained depth to mottliing
-0-4 inches
Poorly drained depth to mottling
4-8 inches
Somewhat poorly drained depth to mottling
8-16 inches
moderatley well drained depth to mottling
16-40 inches
well drained depth to mottling
> 40 inches
differences between reduced mottling and oxidized mottling
- oxidized in red, yellow, and bright (Fe +3)
- Reduced is grey, gley, and dull (Fe +2)
Esker
- coarse sands/gravel throughout
- Excessively well drained
Soil color–munsell notation
- Hue, relation to red, yellow, green, blue, purple
- Value- lightness (10 white, 1 black)
- Chroma - departure from neutral of the same lightness
- describes location in 3D color space, written as hue value/ chroma (1.5yr/4)
Soil profile horizon description (components)
- color
- horizon boundary
- coarse fragments
- depth to mottling, root restrictive layer
- roots (size and abundance)
What has an influence on soil drainage class
-landscape shape, position, slope, and topography
Size class of roots
- very fine (<1mm)
- fine (1 - 2mm)
- Medium (2 - 5mm)
- Coarse (5 to 10mm)
- very coarse (>10mm)
Root abundance
-few <1
-Common 1 to 5
Many greater than or equal to 5
what contributed to the fall of Mayans
- Overpopulation
- soil degradation
- competition among villages for resources
Anthopogenic disturbance of the NE landscape
- 1740, clearing of land for homesteads
- 1830, height of cultivation
- 1850, beginning of land abandonment
Alluvial (fluvial)
- deposited by streams
- particles are coarse, bigger
-Lacustrine
- deposited by lakes
- variable size, size of particles depends on the speed of the water
- means glacial lake
Till
- angular shape, not rounded
- deposited by ice
- Basal - crushed at bottom where ice melts, impermeable at water, dense
- Ablation - ice with a lot of stuff in it, loose
Marine
- deposited by the ocean
- texture depends on the source
- east coast is coarse texture
Outwash
-coarse texture, moves in water, becomes smooth and rounded
Deposited by WATER (stratified)
- outwash
- Marine
- Alluvial
- Lacustrine
Deposited by ICE
-Till
5 factors of Jennys state model for soil formation
- climate
- time
- organisms
- parent material
- topography
Jennys state model CLIMATE
- active
- temperature, when the temp is warmer, the soil will form quicker
- effective precipitation
Jennys state model ORGANISMS
- active
- plants
- breaking down organic matter and adding nutrients to soil
- organisms mound, mix, form and fill voids, and form/destroy peds
Jennys state model PARENT MATERIAL
- determines how the soil will form as well as the texture
- passive
Jennys state model TOPOGRAPHY
- the slope and aspect of the land greatly influence how the soil develops
- passive
Jennys state model TIME
- soils need time to develop, so a longer time frame leaves more time to develop a soil profile
- passive
Material depeosited by wind
-Eolian or Aeolian
What are the 3 most common elements in earth crust?
-Al, Si, O
Backslope
-WD and MWD till
Footslope
-SPD and PD till
Toe Slope
VPD, organic soil
Mineral
-specific chemical composition and specific arragement
Primary minerals
- have not been altered since deposition (quartz, olive)
- silicate materials
Secondary minerals
- have been altered/weathered (clay)
- silicate clay materials
Igneous rocks
cooling of magma
sedimentary rocks
collection of particles that solidify under pressure
metamorphic rocks
mix of igneous/sedimentary, heat and pressure applied overtime
Mull
-thick A horizon, very thin litter layer
Duff mull
-thick litter horizon, moderatley thick A horizon followed by E
MOR
-thick litter horizon with small A, E horizons, mostly composed of bedrock
_____ has greatest potential for high vegetative productivity
-Mull
Coarse grained rocks weather to
-coarse (sandy) textured soils
Limestone, marble weather to
-medium textured soil (silt, loamy)
Shale, slate weather to
-fine (clay) textured soil
Earth’s crust + weathering agents =
parent material
-Weathering of earths crust creates parent material
soil parent material + weathering agents =
soil
-weathering of parent material creates soil
Soil formation, Process model
- Transformation
- Translocation
- Addition
- Loss of material
Transformation in process model
- mineral weathering and organic matter breakdown
- destruction, modification, synthesis
Translocation in process model
- transloaction of organic and inorganic material
- occurs in 3 dimension
Addition in process model
-addition of soil materials from the outside soil profile
Two types of mineral weathering
- Disintegration (physical)
- Biogeochemical weathering
Physical weathering
- temperature (can break things apart)
- Ablation (water, ice, wind)
- plants and animals (roots splitting sidewalks)
Biogeochemical weathering
- Hydration (water molecules are incorporated into structure)
- Hydrolosis (splitting of water)
- Dissolution (decomposition of ions)
- Redox (exchanging of electrons)
- Complexation (adding organic molecules)
- Acid/base (changing pH of structure)
Podzolization
- Precip>PET
- cool, moist temp
- Soil order : spodosol
- E, Bs horizons
Laterization
- Precip>PET
- desilication, low Si
- hot, moist temp
- Ap, Bo horizons
- Oxisol soil order
Calcification
- Calcium accumulates
- precip
Gleization
- anerobic, gleyed horizon
- reduced iron
In arid regions, which weathering process is expected to dominate?
-Physical
Soil texture
-relative proportion of primary particles (sand, silt, clay)
Larger particles are called
- Sand
- 2 - 0.05mm
- irregular size and shape
- primarily quartz
Particles >2mm are
-rocks, coarse fragments
-smaller particals are called
-clay, diameter < .002mm
medium size particles are called
- silt
- .05-.0002mm
- irregular size and shape
Sandy soils characteristics
- low water holding capacity, organic matter, and compaction potential
- susceptible to wind erosion
- resist water erosion
- rapid drainage, well aerated
Silty soils characteristics
- medium water holding capacity, organic matter, and fertility
- very susceptible to wind and water erosion
- moderate aeration
wind blown silt deposits are
loess
clay soils characteristics
- slow drainage, poor aeration
- high water holding capactiy, organic matter, fertility