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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
Capillary Water
Water within soil micropores, available for plant use
26
Gravitational Water
Water within soil macropores
27
Filled Capacity
The optimal point of water saturation for plant growth The condition in which approx. 1/2 of pore space is filled with water
28
Wilting Point
The minimal point of water saturation required for plants to survive (w/o wilting)
29
Permanent Wilting Point
The point of water saturation where plants cannot take water from the soil and will not recover even if water is added
30
Maximum Capacity
The point where all pore space in the soil is filled with water The maximum amount of water the soil can hold
31
What are the two best ways to slow evaporation from the soil?
Increase ground plant cover Increase plant canopy cover
32
What does air accomplish within the soil
Allows respiration in microbes and plants
33
How does air composition within soil compare to atmospheric air?
They are mostly the same
34
What is the most important factor in determining soil aeration? What two factors affect that?
Macropore size Soil Structure and texture
35
What 3 factors can characterize soil aeration?
- Oxygen content - Soil oxidation - Air-filled porosity
36
Mass Flow
Air moved by root and water movement
37
What is the primary mode of air movement?
Diffusion
38
What 3 factors affect oxygen availability in soil?
- Macropore quantity - Amount of microbial respiration - Water content
39
How much faster does oxygen diffuse in pore spaces filled with air versus water?
10X
40
What color soil does anaerobic oxidation cause?
Gray
41
Redoximorphic Features
Red and black splotches in soil caused by iron and manganese oxides
42
Which types of soil change temperature faster?
Bare soils and dry soils
43
Specific Heat
The amount of energy required to increase 1g of soil by 1 degree
44
Respiration rates in soil double for every _ increase in temperature
10 degrees (up to 35)
45
Why do soils in different areas have different respiration rates?
The amount/types of plants present
46
What are five ecological processes does soil aeration affect?
- Organic matter decomposition - Oxidation - Soil Color - Methane Production - Activities of higher plants
47
Ogallala Aquifer
The aquifer that supplies much of the great plains region, supplies 30% of water used in agriculture
48
Forbes
Shrubbery
49
Soil Colloids
The smallest particles in a soil, in the form of clay and humus Solid phase components of cation/anion exchange in soil
50
Polysillicates
The structure of clay colloids Forms thin layers of tetrahedrals and octohedrals
51
1:1 silicate clay
A polysilicate clay consisting of equally alternating layers of tehtrahedral and octahedrals Not prone to stretch/shrink, and good for agriculture
52
2:1 silicate clay
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
Crystalline Clay Silicate
Silicate clay consisting of 1:1 clay w/ tight bonds of oxygen, silicone, and aluminum Usually negatively charged
54
Non-Crystalline Clay Silicate
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
Most common colloid in soil
Crystalline clay silicate
56
Oxides
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
2 Major Sources of Charge in Soil
- Hydroxyls/changing pH - Constant charge/charge by isomorphic substitution
58
Hydroxyl Group
A molecule consisting of an oxygen atom bound with 2 hydrogen atoms
59
Isomorphic Substitution
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
Humus
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
What is the smallest colloid?
Humus
62
How much more carbon is contained in the soil than in all organic matter on earth?
3X
63
Carbon offset
A tract of land left undeveloped for purpose of trapping CO2 in soil
64
What 5 functions does increased soil organic matter improve?
- Water infiltration - Water retention - Cation Retention - Soil structure - Nutrient cycling
65
What are the four primary contributors to soil organic matter, in order from most to least contribution
- Grasses - Forbes - Trees - Animals
66
Lignin
Supportive tissue found in vascular plants The older the plant, the more lignin is present
67
3 stages of organic matter decomposition
- Litter - Duff (feels like OM, but not recognizable) - Humus
68
45% of all soil carbon is contained in what 3 soil orders?
Histisols Inceptisols Gelisols
69
What 2 factors influence biomass degredation?
Soil conditions Quality of added plant residue
70
What is the maximum carbon to nitrogen ratio in soil to support plant life?
25:1
71
Vermicomposting
Composting aided by earthworms
72
Thermophylic Composting
Intense decomposition caused by large, well-aerated piles that generate lots of heat
73
What 4 functions does organic matter perform in soil?
- Decomposition of organic materials - Transform organic matter into usable compounds - Release plant nutrients into soil - Pollution control
74
How much matter do earthworms consume in a day? In a year?
Their body weight each day 10 tons per acre per year
75
Functional Diversity
Number of biological processes occurring in a sample
76
What are the three way to measure biological activity in a soil?
- Measure population - Measure biomass - Measure Metabolic activity
77
What type of soil are molds found in?
Acidic soils
78
Mychorrizae
Fungus roots, often connect to plants
79
Actinomycetes
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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