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Earth 122 > Chapter 7: Soils > Flashcards

Chapter 7: Soils Flashcards

1
Q

What is the Meur Bleu bog?

A

The Meur Bleue bog is a 35km^2 protected wetland located east of Ottawa.

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2
Q

What type of soil does the Mer Bleue wetland have?

A

Peat. (deposits formed over 800 yrs and are up to 6m thick)

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3
Q

Why are Northern peatlands important?

A

They are storage reservoirs for carbon, holding about one 3rd of all carbon stored in soils.

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4
Q

How much energy does all the peat in the world contain?

A

8 billion terajoules

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5
Q

Fill in the blanks: The formation of peat is often the first step of ______, such as ________.

A

the first step of the [geological formation of fossil fuels] such as COAL

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6
Q

How does peat produce soil gases such as CO2 and CH4?

A

Through decomposition of organic matter

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7
Q

How does climate change affect soils?

A

Warming can lead soils to decompose at faster rates and thus release more soil gases, created a higher concentration of carbon-gas in the atmosphere.

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8
Q

What is the difference between soil and dirt?

A

Dirt: loose material derived from rock
Soil: A complex plant supporting system consisting of weathered rock, organic matter, water, gases, nutrients, and microorganisms

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9
Q

Define: Parent Material (soils)

A

the base geological material from which the soil is formed

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10
Q

What is soil solution?

A

Water that partially fills the open space in soils. This is never “pure” water, contains dissolved minerals and organics

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11
Q

How does the formation of soil begin?

A

When the parent material is exposed to the effects of the atmosphere/hydrosphere/biosphere(weathering)

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12
Q

Give examples of possible parent material for soils

A

Lava, volcanic ash, rock/sediment deposited by water bodies, most commonly bedrock(earth’s crust)

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13
Q

What are the processes most responsible for soil formation?

A

Weathering, erosion, deposition and decomposition of organic matter

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14
Q

Define: Regolith

A

Small, loose particles of mineral matter, precursors of soils

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15
Q

Give examples of physical weathering

A

temperature, wind, rain, ice, (thermal expansion/contraction)

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16
Q

How is the air in soil different from the air we breathe?

A

soil air contains gases that are released from underlying rock, and gases that infiltrate from above such as constituents from spilled gas and oil

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17
Q

Name and briefly describe the five factors that influence soil formation

A

CLIMATE: -soil forms faster in warm, wet climates
-heat accelerates weathering, decomposition, biological growth
ORGANISMS: -worms and other burrowing animals facilitate soil processes. organic matter affects soil’s composition
TOPOGRAPHY: -hills and valleys affect exposure to the sun,wind,water, influence how soil and water move.
-steep slope results in more runoff and erosion
PARENT MATERIAL: chem/physical attributes of parent material influence soils properties
TIME: soil formation occurs over long periods of time

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18
Q

Describe Biological Weathering

A

occurs when living things break down parent material by physical or chemical means(ex. lichens produce acid which chemically weathers rock)

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19
Q

Define: Humus

A

dark, spongy, crumbly material made up of complex organic compounds

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20
Q

Define: Horizon(soils)

A

Each layer of soil

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21
Q

Soil Profile

A

The whole cross section of soil, from surface to bedrock

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22
Q

Leaching

A

a process in which materials suspended or dissolved in liquid are transported through the soil subsurfacw

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23
Q

Litter

A

soil surface deposits of leaves, branches, animal waste etc.

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24
Q

Name the 5 major types of soil horizons in order

A

O, A, B, C, R (only able bodies can run)

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25
Q

O horizon

A

1st layer. peat deposits

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26
Q

A horizon

A

2nd layer. uppermost mineral horizon, TOPSOIL(most vital to ecosystems and agriculture)

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27
Q

B horizon

A

3rd layer. SUBSOIL, hard mineral rich layers

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28
Q

C horizon

A

4th layer, Broken parent material, transition zone

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29
Q

R horizon

A

5th layer, Unaltered parent material ROCK, layer

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30
Q

How are soils classified?

A

classified into 10 major groups called orders, with dozens of “great groups” and hundreds of “subgroups” . Classified using different properties such as colour, texture, structure, and pH

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31
Q

What is indicated by soil colour?

A

Colour of soil can indicate chemical composition and sometimes its organic content

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32
Q

What does dark soil indicate? Pale/white soil?

A

Black/dark brown: usually rich in organic matter

Pale grey/white: chalky composition, calcium carbonate deposits, salt deposits, leaching

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33
Q

What are the three categories of Soil Texture?

A

Clay: consists of particles less than 0.002 mm in diameter
Silt: 0.002 to 0.05mm
Sand: 0.05 to 2mm

34
Q

What does the texture of soil determine?

A
  • texture influence how porous the soil is
  • influences permeability: the ease with which fluids can move (bigger grains, increased permeability)
  • silt or loamy soils are best for plant growth
35
Q

loam

A

mixture of clay,silt,sand

36
Q

What is soil structure?

A

The measure of the organization or clumpiness of soil. Large soil clumps can discourage plant growth

37
Q

Define plowpan

A

when farmers repeatedly till the same field, and end up forming a crusty hardpan layer that resists water infiltration

38
Q

What is soil pH?

A

The degree of acidity(low pH) or alkalinity(high pH, basic) of a soil. Influence soil’s ability to support plant growth.

39
Q

How do materials that move through soils gain their nutrients?

A

ION EXCHANGE: a process in which positively charged particles(cations) and negatively charged particles(anions) are exchanged between soil and soil solution.

40
Q

Cation exchange

A

process that allows plants to gain nutrients

41
Q

cation exchange capacity

A

a soil’s ability to hold cations, preventing them from leaching, thereby increasing their availability to plants(greatest in FINE soils)

42
Q

When soil pH decreases, cation exchange capacity _______

A

diminishes, nutrients leach away

43
Q

What are examples of positively charged pollutants?

A

Cadmium, lead, arsenic, mercury

44
Q

What is nitrogen fixation and how can it be accomplished?

A

Nitrogen fixation is when nitrogen gas combines with hydrogen to form NH4(ammonium). This can be accomplished when air in the top layer of soil comes in contact with specialized nitrogen-fixing bacteria.

45
Q

Define Nitrification

A

when specialized bacteria convert ammonium ions into nitrite ions(NO2-), then into nitrate ions(NO3-)

46
Q

Define Denitrification

A

When bacteria converts nitrates in soil or water into gaseous nitrogen(N2). Completes the nitrogen cycle by releasing nitrogen back into atmosphere.

47
Q

Why is soil important in the carbon cycle?

A

Soil is the largest ACTIVE terrestrial reservoir for carbon

48
Q

What are the main carbon fluxes soil is involved in?

A

Photosynthesis and production of organic matter, followed by respiration and decay of organic matter

49
Q

Wet soils are more likely to be _______ than dry soils

A

anaerobic(oxygenated)

50
Q

How does rain affect soil productivity?

A

High amounts of rainfall can cause leaching of nutrients, therefore making the soil less productive

51
Q

What continent is the proportion of soil erosion largest? Which continents is soil erosion a growing concern?

A

Europe. Africa and Asia.

52
Q

What factors affect soil degradation?

A

Overgrazing(34%), deforestation(30%), cropland agriculture(28%), other overexploitation(7), industrialization(1)

53
Q

What are the main limitations of soil productivity?

A

Shallow soil, contaminated soil, dry soil

54
Q

Where is the majority of organic matter stored in tropical forests? In boreal/temperate forests? In desert biomes?

A

The majority of organic matter in tropical forests is stored ABOVE ground in plant biomass. In boreal/temperate forests, most organic matter is stored in soils. In deserts, there is little organic material because of the low amount of biomass.

55
Q

How have humans increased erosion

A

Overcultivating fields, overgrazing(livestock), clear cutting forests

56
Q

What type of erosion has the greatest potential to move topsoil?

A

Rill erosion, followed by sheet erosion and splat erosion

57
Q

How does wind(aeolian) erosion work?

A

Wind erosion occurs when all loose, fine grained material is picked up from the surface and carried away by wind

58
Q

What is the Universal Soil Loss Equation?

A

A= R K LS C P
(A = r kelly likes silly cat pictures)
A- predicted soil loss due to water erosion
R- erositivity factor
K- soil erodibility factor
LS- slope length and steepness
C- vegetative cover and management factor
P-erosion control practices factor(conservation)

59
Q

What is splash erosion?

A

Splash erosion is when raindrops strike the ground with enough force to dislodge small amounts of soil

60
Q

When does sheet erosion occur?

A

Sheet erosion occurs when thin layers of water travel broad expanses of sloping land

61
Q

What does rill erosion do?

A

Rill erosion leaves small pathways along the surface where water has eroded topsoil

62
Q

What is gully erosion?

A

Erosion that cuts deep into soil, leaving large gullies (think big holes in ground)

63
Q

What does the wind erosion prediction equation stand for?

E = f(I C K L V)

A 
E-predicted soil loss due to wind
I- soil erodibility factor
C- local wind erosion climate factor
K- roughness factor
L- length of field factor
V- vegetative cover factor
64
Q

What is the primary cause of soil erosion?

A

Humans(said to be 10 times more influential at moving soil than all other natural processes on earth combined)

65
Q

What is desertification?

A

When formerly productive land becomes a desert as a result of climate change or prolonged drought.

66
Q

How much of the earths land surface is affected by desertification?

A

about one third

67
Q

What type of lands are most prone to desertification?

A

Arid and semi-arid lands(low precipitation)

68
Q

What caused the 1930s Dust Bowl?

A

An increased amount of settlers arrived in NA planning to make a living as farmers.. The amount of cultivated land soared..Farmers grew abundant wheat and grazed many thousands of cattle, breaking down soil structure.
When the stock market crashed in 1929, a cycle of poverty and land degradation befan. A prolonged drought accelerated the negative impacts of the soil.. strong winds began to carry away millions of tonnes of topsoil, creating dust storms.

69
Q

(SOLUTIONS) what is crop rotation?

A

the practice of alternating the kind of crop grown in a particular field from one year to the next. (can return nutrients to the soil, break cycles of disease, minimize erosion)

70
Q

(SOLUTIONS)what is intercropping? How does this help slow erosion?

A

Planting different types of crops in alternating bands or other mixed arrangements. This helps slow erosion by providing more ground cover than a single crop does.

71
Q

What is agroforestry?

A

When crops are interplanted with trees. More productive than just planting food crops alone.

72
Q

(SOLUTIONS) What is contour farming?

A

When furrows are ploughed sideways across a hill perpendicular to its slope to prevent formation of rills and gullies. (furrows follow the nature contours of the land.)

73
Q

(SOLUTIONS) What is terracing?

A

Level platforms cut into steep hillsides to contain water from irrigation and precipitation(staircase-like layers). The most effective method for preventing erosion on extremely steep terrain.

74
Q

(SOLUTIONS) What are shelterbelts(windbreaks)?

A

Rows of treees or shrubs planted along the edges of fields to slow wind.

75
Q

What is alley cropping?

A

When shelterbelts are combined with intercropping

76
Q

What is tillage erosion?

A

When soil is loosened due to overturning, making it more likely to move downslope due to gravity

77
Q

What is irrigation?

A

Artificially providing water for agriculture

78
Q

What is waterlogging and how is it harmful?

A

Waterlogging is the overirrigation of soils, suffocates plant roots

79
Q

What is salinization?

A

The buildup of salts in surface soil layers

80
Q

What is fertilizer?

A

substances that contain essential nutrients

81
Q

What is biochar?

A

Biomass reduced to a black, carbon-rich, charcoal-like residue. Effectively holds on to plant nutrients and heavy metals

82
Q

about how long does it take for 10 cm of soul to be created?

A

2000yrs

Earth 122 (15 decks)

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