soils Flashcards

1
Q

geologic definition of soil

A

earth material that has been altered to support rooted plant life

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2
Q

engineering definition of soil

A

earth material that can be removed without blasting

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3
Q

soil horizons in order from top to bottom

A

O, A, E, B, C

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4
Q

O horizon?

A
  • most organic materials including decomposing plant material
  • dark brown/black
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5
Q

A horizon?

A
  • organic materials and clay
  • minerals and organics
  • light black/brown
  • moves clay and materials to B horizon
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6
Q

E horizon?

A
  • clay and less organics
  • light-colored materials from clay leaching
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7
Q

B horizon?

A
  • ions precipitate to form new materials
  • rich in clay, iron oxides, silica, carbonate, leached materials
  • slightly reddish due to oxidation
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8
Q

C horizon?

A
  • transition to substrates
  • partially altered parent material
  • usually stained red with iron oxides
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9
Q

why do soils have color?

A

indicates presence of water and organic materials
- more organic material = darker
- zone of leaching = lighter
- presence of clay and iron oxides = redder

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10
Q

what do changes in color indicate about drainage?

A
  • well-drained and aerated = red
  • poorly drained = yellow
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11
Q

how do soils become fertile?

A

soil fertility: capacity of soils to support nutrients needed for plant growth

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12
Q

hydraulic conductivity?

A

measure of ability of particular material to allow water to move through it

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13
Q

when did sediment yields peak in the piedmont region and what caused it?

A

peaked in ~1960-1963 due to construction phase of urbanization which increased runoff and erosion

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14
Q

how does agricultural soil erosion influence the amount and fertility of soil?

A
  • temporarily increase fertility due to artificial fertilizers
  • can expose and dry topsoil
  • using too many nutrients can lower fertility
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15
Q

methods of combatting agricultural soil erosion

A
  • contour plowing
  • no-till agriculture
  • terracing slopes
  • planting more than one crop
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16
Q

where is soil erosion a problem?

A

agriculture, off-road vehicle/walking, urbanization

17
Q

how does soil erosion occur in agriculture?

A

affects topsoil by potentially drying it out

18
Q

how does soil erosion occur in off-road vehicles and walking?

A

compaction of soil
- soil erosion
- damage to hydrology
- disturbs plants/animals

19
Q

how does soil erosion occur in urbanization?

A
  • increases soil erosion
20
Q

how does urbanization increase soil erosion?

A
  • sensitive soils lost
  • materials that are brought may change soil makeup
  • draining soils can dry them out and change properties
  • susceptible to pollution due to chemicals added