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EoSC Spring Semester > Soil Science Q2 > Flashcards

Soil Science Q2 Flashcards

1
Q

Adhesion

A

The attraction of water molecules to solid surfaces

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2
Q

Cohesion

A

The attraction of water molecules to each other

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3
Q

Surface Tension

A

Greater attraction of water molecules to each other than to the air

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4
Q

What are the six functions water performs in soil?

A
  • Facilitates plant life
  • Facilitates for microbial life
  • Temperature regulation
  • Facilitates soil formation
  • Breaks down waste
  • Acts as part of water cycle
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5
Q

What is the prime driver of the water cycle?

A

Solar energy

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6
Q

Interception

A

Precipitation that doesn’t reach soil (e.g. blocked by plant cover)

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7
Q

Runoff

A

Precipitation that flows away from the area via stream channels

Can be surface or groundwater

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8
Q

Infiltration
Vs.
Percolation

A

Downward movement of water into the soil
Vs.
Downward movement of water within the soil

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9
Q

Transpiration

A

The process of water being absorbed and released by plants without reaching the soil

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10
Q

Watershed

A

A group of groundwater separated from other groups of groundwater via drainage or dam structures

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11
Q

Riparian Area

A

The stretcher of land near the shore of a body of water

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12
Q

What four functions does a riparian area with lots of plant cover perform?

A
  • Stabilizes banks and reduces erosion thereof
  • Provides food and shelter to a large variety of organisms
  • Controls pollution by reducing release of nutrients, waste, and sediment into water
  • Increases aesthetic and recreational value of land
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13
Q

Where is the majority of freshwater found (and what percentages)

A
  • 68.7% in glaciers
  • 30% in groundwater
  • 1.2% usable
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14
Q

What percentage of water usage is used in agriculture

A

70%

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15
Q

What 3 factors cause water to be scarcer in some areas than others?

A
  • Unequal water distribution
  • Unequal population distribution
  • Flood irrigation
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16
Q

What are two practices that can increase our available water?

A
  • Desalinization
  • Drip irrigation
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17
Q

Aquifer

A

A body of rock/soil that holds groundwater

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18
Q

Saturated Flow

A

Movement of water in soil where both micropores and macropores are filled with water
Movement controlled by macropores via gravity

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19
Q

Unsaturated Flow/Capillary Movement

A

Movement of water in soil where micropores but not macropores are filled with water

Movement is controlled by adhesion and surface tension/cohesion

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20
Q

Vapor Flow

A

Movement of water in very dry soils
Movement controlled by evaporation

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21
Q

Darcy’s Law

A

Water moves from areas of low matric potential to high matric potential

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22
Q

Matric Potential/Water Potential

A

The strength of attraction between a soil particle and its surrounding water

Drier soils have higher Matric potential

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23
Q

Hydraulic conductivity

A

The ease with which water moves within the soil

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24
Q

Hygroscopic Water

A

Water that forms a film around soil particles, not available for plant use

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25
Q

Capillary Water

A

Water within soil micropores, available for plant use

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26
Q

Gravitational Water

A

Water within soil macropores

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27
Q

Filled Capacity

A

The optimal point of water saturation for plant growth

The condition in which approx. 1/2 of pore space is filled with water

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28
Q

Wilting Point

A

The minimal point of water saturation required for plants to survive (w/o wilting)

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29
Q

Permanent Wilting Point

A

The point of water saturation where plants cannot take water from the soil and will not recover even if water is added

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30
Q

Maximum Capacity

A

The point where all pore space in the soil is filled with water

The maximum amount of water the soil can hold

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31
Q

What are the two best ways to slow evaporation from the soil?

A

Increase ground plant cover
Increase plant canopy cover

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32
Q

What does air accomplish within the soil

A

Allows respiration in microbes and plants

33
Q

How does air composition within soil compare to atmospheric air?

A

They are mostly the same

34
Q

What is the most important factor in determining soil aeration?

What two factors affect that?

A

Macropore size

Soil Structure and texture

35
Q

What 3 factors can characterize soil aeration?

A
  • Oxygen content
  • Soil oxidation
  • Air-filled porosity
36
Q

Mass Flow

A

Air moved by root and water movement

37
Q

What is the primary mode of air movement?

A

Diffusion

38
Q

What 3 factors affect oxygen availability in soil?

A
  • Macropore quantity
  • Amount of microbial respiration
  • Water content
39
Q

How much faster does oxygen diffuse in pore spaces filled with air versus water?

A

10X

40
Q

What color soil does anaerobic oxidation cause?

A

Gray

41
Q

Redoximorphic Features

A

Red and black splotches in soil caused by iron and manganese oxides

42
Q

Which types of soil change temperature faster?

A

Bare soils and dry soils

43
Q

Specific Heat

A

The amount of energy required to increase 1g of soil by 1 degree

44
Q

Respiration rates in soil double for every _ increase in temperature

A

10 degrees (up to 35)

45
Q

Why do soils in different areas have different respiration rates?

A

The amount/types of plants present

46
Q

What are five ecological processes does soil aeration affect?

A
  • Organic matter decomposition
  • Oxidation
  • Soil Color
  • Methane Production
  • Activities of higher plants
47
Q

Ogallala Aquifer

A

The aquifer that supplies much of the great plains region, supplies 30% of water used in agriculture

48
Q

Forbes

A

Shrubbery

49
Q

Soil Colloids

A

The smallest particles in a soil, in the form of clay and humus

Solid phase components of cation/anion exchange in soil

50
Q

Polysillicates

A

The structure of clay colloids

Forms thin layers of tetrahedrals and octohedrals

51
Q

1:1 silicate clay

A

A polysilicate clay consisting of equally alternating layers of tehtrahedral and octahedrals

Not prone to stretch/shrink, and good for agriculture

52
Q

2:1 silicate clay

A

A polysilicate clay consisting of layers of octahecrals sandwiched between layers of tetrahedrals

Twice as many tetrahedral layers as octahedral layers

Prone to stretch/shrink, and therefore poor for agriculture/construction

Good for lagoons/ponds

53
Q

Crystalline Clay Silicate

A

Silicate clay consisting of 1:1 clay w/ tight bonds of oxygen, silicone, and aluminum

Usually negatively charged

54
Q

Non-Crystalline Clay Silicate

A

Silicate Clay consisting of 2:1 clay w/ loose bonds of oxygen, silicone, and aluminum

Usually negatively charged w/ high capacity for cation exhange

55
Q

Most common colloid in soil

A

Crystalline clay silicate

56
Q

Oxides

A

Colloids in soil consisting of iron oxide, aluminum oxide, oxygen, and hydrogen

Non-expanding, non-plastic, and low cation exchange potential

Can be positive or negative

Most common in old soils (ultisols, oxisols)

57
Q

2 Major Sources of Charge in Soil

A
  • Hydroxyls/changing pH
  • Constant charge/charge by isomorphic substitution
58
Q

Hydroxyl Group

A

A molecule consisting of an oxygen atom bound with 2 hydrogen atoms

59
Q

Isomorphic Substitution

A

The isotope normally present in the soil has been replaced by a different yet similar isotope, resulting un a continuous charge equivalent to the charge difference between the two isotopes

60
Q

Humus

A

Dirt formed from organic matter (must be no longer recognizable as organic matter)

Nonmineral, noncrystaline substance made from chains or rings of carbon

High water/cation absorption potential, not sticky or pliable, but prone to changes in pH

61
Q

What is the smallest colloid?

A

Humus

62
Q

How much more carbon is contained in the soil than in all organic matter on earth?

A

3X

63
Q

Carbon offset

A

A tract of land left undeveloped for purpose of trapping CO2 in soil

64
Q

What 5 functions does increased soil organic matter improve?

A
  • Water infiltration
  • Water retention
  • Cation Retention
  • Soil structure
  • Nutrient cycling
65
Q

What are the four primary contributors to soil organic matter, in order from most to least contribution

A
  • Grasses
  • Forbes
  • Trees
  • Animals
66
Q

Lignin

A

Supportive tissue found in vascular plants

The older the plant, the more lignin is present

67
Q

3 stages of organic matter decomposition

A
  • Litter
  • Duff (feels like OM, but not recognizable)
  • Humus
68
Q

45% of all soil carbon is contained in what 3 soil orders?

A

Histisols
Inceptisols
Gelisols

69
Q

What 2 factors influence biomass degredation?

A

Soil conditions
Quality of added plant residue

70
Q

What is the maximum carbon to nitrogen ratio in soil to support plant life?

A

25:1

71
Q

Vermicomposting

A

Composting aided by earthworms

72
Q

Thermophylic Composting

A

Intense decomposition caused by large, well-aerated piles that generate lots of heat

73
Q

What 4 functions does organic matter perform in soil?

A
  • Decomposition of organic materials
  • Transform organic matter into usable compounds
  • Release plant nutrients into soil
  • Pollution control
74
Q

How much matter do earthworms consume in a day?

In a year?

A

Their body weight each day

10 tons per acre per year

75
Q

Functional Diversity

A

Number of biological processes occurring in a sample

76
Q

What are the three way to measure biological activity in a soil?

A
  • Measure population
  • Measure biomass
  • Measure Metabolic activity
77
Q

What type of soil are molds found in?

A

Acidic soils

78
Q

Mychorrizae

A

Fungus roots, often connect to plants

79
Q

Actinomycetes

A

Bacteria-like organisms that that have branching roots like fungi

Responsible for dirt smell

Prefers warm, moist, pH-neutral soils

EoSC Spring Semester (13 decks)

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