General soil Flashcards
(114 cards)
1
Q
What are 5 reasons we should examine soils?
A
- Food production (through crops)
- Provides a metric of biological diversity
- Carbon cycling
- Water quality
- Plant respiration/photosynthesis
2
Q
What are the 6 main functions of soil?
A
- Water supply & purification
- Medium for plant growth
- Habitat for organisms
- Nutrient/waste recycling
- Engineering medium
- Atmospheric modifier
3
Q
What are the 4 soil forming processes?
A
- Transformation
- Translocation
- Addition
- Loss
4
Q
What are the 3 common soil physical properties?
A
- Density
- Texture
- Color
5
Q
FITB: Soil textures can have different ____________ for sands, silt and clay
A
Thresholds
6
Q
FITB: Sands are mainly composed of ______ grains
A
Quartz
7
Q
How do sands feel?
A
Gritty
8
Q
T/F: Sand grains are not visible to the naked eye
A
False; they are
9
Q
Do sands have high or low surface areas?
A
Low
10
Q
Why are plants unable to grow in sandy soils?
A
Because there are very few nutrients found within sands
11
Q
T/F: Sand cannot store water
A
True
12
Q
Does water move slowly or quickly through sand?
A
Quickly
13
Q
FITB: Silts are composed of ____-sand particles
A
Micro
14
Q
What does silt feel like?
A
Smooth, chalky, like flour
15
Q
T/F: Silt is sticky when wet
A
False
16
Q
T/F: Silt particles can be seen by the naked eye with no microscope needed
A
False; visible in field lens
17
Q
T/F: Silt can hold more water than sand
A
True
18
Q
Does silt have a higher or lower surface area?
A
Higher
19
Q
What is a unique characteristic of silt?
A
It releases plant-available nutrients
20
Q
What is the texture of clay like?
How does it appear to the eye?
A
Flat; plate-like
21
Q
How is clay formed?
A
From weathering
22
Q
What does clay feel like?
A
Sticky, plastic-like
23
Q
T/F: Clay can be molded
A
True; think of art projects you did as a kid
24
Q
FITB: When clay is dry, it can be described as a ____ mass
A
Hard
25
Does physical or chemical weathering occur with clay?
Chemical
26
T/F: Clay cannot shrink nor can it swell
False; it can do both of these things
27
Does clay have a high or low surface area?
Very high
28
Soil textural classes are made up of ______, ________, & _______
1. Sand
2. Silt
3. Clay
29
T/F: Soil color does control the processes within the soil
False
30
TOT: Soil color can indicate that something has stayed the same/changed in the soil
Changed
31
Color wise, what colors make up a soil with silts & clays?
Brown, tan, yellow
32
How can you tell if there is a lack of other particles such as silt and clay?
If there is only sand left in the soil
33
T/F: The wetter the soil, the lighter it will be
False! It will definitely be darker in color
34
What does oxidation state mean?
The availability of oxygen within the soil
35
If you have oxidized iron, what color is going to appear?
Rust color (orange)
36
When iron is reduced, what color does it become?
Gray
37
Oxidized environments can be associated with well/poor drained environments?
Well-drained
38
T/F: Reduction is the opposite of oxidation
True
39
What is the Munsell Color System?
A book that contains a numerical system in which one can associate soil sample colors with (to compare)
40
Munsell colors are arranged according to 3 features; which are these 3 features? (in order)
1. Hue - how red/yellow (10YR)
2. Value - Light or dark (8-light, 1-dark)
3. Chroma - Brightness/intensity
41
10YR 5/3 is an example of a _________ color
Munsell
42
T/F: Volcanic rocks can make soil black/dark
True
43
Does dark soil always mean that is organic matter?
No
44
Name the process: very little presence of oxygen is called ________ while an abundance of water + oxygen + iron is called ________
1. Reduction
2. Oxidation
45
T/F: Volcano soils are not rich or fertile due to their lack of organic matter
False
46
Is agriculture successful in places with volcano soils? Why?
Yes because they have rich & fertile soils with organic matter that cannot breakdown (so it stays still)
47
Pine trees add ______ to soil profiles
Acids
48
Pure sands come from _________
Quartz
49
T/F: Calcium/sodium deposits can make white layers within soils
True!
50
Soil structure is made up of the arrangement of sand, silt, clay and organic matter which forms into ____________
Aggregates
51
What are aggregates?
Smaller particles that come together that form a larger particle
52
Why do aggregates form/come together?
Because of soil glue (sticky stuff)
53
FITB: Aggregate formations can be in a ________, _______ or ________ form
1. Physical
2. Chemical
3. Biologic
54
FITB: Aggregates have the ability to shrink/_____, and ______/thaw
1. Swell
2. Freeze
55
What is flocculation?
The attraction of 2 particles together due to charges/the mutual attraction among clay and organic molecules (like magnets)
56
Aggregate formation dispersion (breaking apart the structure) occurs with which common element?
Sodium
57
FITB: Aggregate formation can occur with exudate, _______ or living matter
Residue
58
What are the 5 main structural shapes of soils?
1. Granular - found at surface
2. Blocky - found underground
3. Platy - flat, sign of compaction occurring
4. Prismatic/Columnar - forms in lower B/C horizons, lots of clay, column-like
5. Structureless - Single grain, massive clays that are random + chunky
59
What are the 5 factors that affect Bulk Density?
1. Organic matter
2. Poor aggregation
3. Grain size
4. Soil flora + fauna
5. Depth of sample
60
What is porosity?
The amount of empty space found within soils
61
MC: The amount of empty space (porosity) in clays is...
A. Poorly aggregated
B. Somewhat aggregated
C. Well-aggregated
D. Compacted
C. Well-aggregated
62
Do clays hold more or less organic matter?
More
63
Are the pores in clays smaller or larger? (Consider particle size and if it can be seen with the naked eye)
Smaller (more pore space)
64
MC: The amount of empty space (porosity) in sands is...
A. Poorly aggregated
B. Somewhat aggregated
C. Well-aggregated
D. Compacted
A. Poorly aggregated
65
Does sand hold more or less organic matter?
Less (remember that plants can't live in sandy soils)
66
Is the pore space in sand less or more?
Less
67
Are sand particles small or large?
Large
68
Low %'s of pore space indicate that what process is occurring within the soil?
Compaction
69
FITB: As % pore space goes down, bulk density goes ___
Up
70
FITB: As % pore space goes up, bulk density goes _____
Down
71
What is the numerical value for Particle Density?
2.65 g/cm³
72
What kind of soil is bulk density composed of?
Dry soil
73
What is Bulk Density?
The weight of a soil in a known volume
74
What is Soil Pore Space?
The % of volume occupied by air & water
75
Bulk Density includes solid + ______ fractions
Pore
76
Why is Bulk Density important?
For agriculture
77
TOT: If you have a higher Bulk Density, that means that you have more/less compaction
More
78
TOT: If you have a lower Bulk Density, that means that you have more/less compaction
Less
79
What is the ideal Bulk Density numerical range for plant growth?
1.2-1.4
80
TOT: When you have higher compaction, it is harder/easier to have air and water pass through the soil
Harder
81
T/F: Minerals are less dense than water
False
82
T/F: Organic matter is more dense than water
True
83
What are the 5 soil forming factors?
1. Climate
2. Biota
3. Relief (topography)
4. Parent material
5. Time
84
What is climate?
The change in atmospheric conditions
85
T/F: Climate does not influence erosion, plant success or mineral breakdown
False
86
When we talk about relief being one of the 5 soil forming factors, what are we really referring to? (Don't say topography)
How hilly/flat your landscape is
87
Relief includes what 5 characteristics?
1. Slope
2. Length
3. Landscape position
4. Elevation
5. Aspect
88
FITB: One of the soil forming factors is time. Time controls the amount of _________ occurring
Interactions
89
Time includes what 3 characteristics?
1. Climate
2. Vegetation
3. Human interactions
90
Biota is composed of _________ __________.
Living organisms
91
What are 4 examples of biota?
1. Microbes
2. Animals
3. Plants
4. Humans
92
T/F: Microbes participate in biological processes such as the act of nitrification
True
93
FITB: Microbes _______ organic matter
Nitrify
94
FITB: Earthworms create _______ in their guts
Calcite
95
What is Pedoturbation?
The physical disturbance & mixing of soil horizons (performed by worms and roots)
96
T/F: Humans were a major force of soil development in the past but no longer are today
False
97
What are the 4 characteristics of Human Influences?
1. Building development
2. Waste
3. Agriculture
4. Climate
98
What is parent material?
The material and process from which soil develops
99
What is weathering?
The deterioration of rock due to breakdown processes
100
What are the 2 types of weathering?
1. Physical (mechanical)
2. Chemical
101
FITB: A physical type of weathering is known as ______'s sandpaper, which is more commonly known as _______ & ________
1. Nature's
2. Impact & abrasion
102
What are 3 things that can cause Impact & abrasion to occur?
1. Wind
2. Water
3. Ice
103
What is meant by impact and abrasion?
Carried particles that scrape against a substance (like a rock)
104
How do grooves (a physical weathering type) form?
When a bigger rock scrapes against bedrock (in which ice then picks it up and carries it across)
105
Is Wedging a physical/chemical type of weathering?
Physical
106
How does wedging occur?
When water enters into cracks of rocks and the water within freezes, the rock expands
107
T/F: Wedging affects small and larger objects
False; just larger objects
108
T/F: Wedging can occur through plants and trees
True
109
Exfoliation is an example of a physical/chemical type of weathering?
Physical
110
What does Exfoliation mean?
The loss of the outer layer of a rock due to expansion
111
Stratification occurs in which type of rock?
A. Limestone
B. Granite
C. Coal
D. Quartz
E. Bedrock
E. Bedrock
112
T/F: Stratification does not need to have some movement (sunlight)
False
113
Stratification is associated with which type of physical weathering?
A. Impact & abrasion
B. Hydration
C. Grooves
D. Exfoliation
D. Exfoliation
114
