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Soil Science > Exam 2 > Flashcards

Exam 2 Flashcards

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1
Q

What is soil texture?

A

The distribution of particles into different size classes less than 2 mm and then divided into sand, silt, and clay.

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2
Q

What particle is greater than 2 mm?

A

coarse fragment or gravel

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3
Q

How large are sand particles?

A

2-0.05 mm

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4
Q

How large are silt particles?

A

0.05-0.002 mm

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5
Q

How large are clay particles?

A

<0.002 mm

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6
Q

What makes a good ribbon?

A

A soil containing more than 40% clay is sticky enough to form a ribbon
2 inches long or longer.

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7
Q

What makes a fair ribbon?

A

A soil containing 27-40% clay is sticky enough to form a ribbon at least 1 inch long but not longer than 2 inches.

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8
Q

What makes no ribbon?

A

The ribbon formed by a
soil containing less
then 27% clay will be
less than 1” long

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9
Q

What does a gritty soil texture tell you?

A

The individual particles are large enough that one can feel a significant number of particles in a moist soil sample.

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10
Q

What does a smooth or slippery soil texture tell you?

A

A soil high in silt will feel smooth (lacking the grittiness of sand) or slippery without feeling sticky (a property of clay).

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11
Q

What does a sticky soil texture tell you?

A

–The feel of a
moist soil sample
which contains
significant amounts of
clay. Stickiness of clay
allows one to form a
ribbon.

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12
Q

What is the hydrometer method?

A

Soil particles are dispersed with a sodium meta-phosphate and then agitated. The different soil particle will then settle at different speeds. Smaller particles settle slowly. Larger particles settle fast.

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13
Q

What soil separate has the largest surface area?
a) Gravel
b) Sand
c) Silt
d) Clay

A

d) clay

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14
Q

What soil separate would have a particle diameter of 0.2 mm?
a) Gravel
b) Sand
c) Silt
d) Clay

A

b) sand

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15
Q

What is the difference between soil texture and structure?

A

Texture refers to the sizes of the individual particles that make up the soil (i.e., sand,
silt & clay).
– Structure refers to how these particles may be stuck together to form crumbs or
larger structures.

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15
Q

What is soil structure?

A

the shape that the soil takes based on its physical and chemical properties.

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15
Q

What is the name of soil aggregates (clumps) that are bound together?

A

Peds

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16
Q

How does soil structure develop?

A

Wetting and drying, burrowing of macroorganisms, and Growth of plant roots.

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17
Q

What soil structure is broken into individual particles that do not stick together. Commonly found in sandy soils and C horizons.

A

Single grained soil structure

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18
Q

What soil structure has no visible structure. Is hard to break apart, appears in very large clods, and is commonly found in the C horizon?

A

Massive soil structure

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19
Q

What soil structure is thin, flat plates of soil that lie
horizontally, which are usually found in compacted soil?

A

Platy soil structure.

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20
Q

What soil structure has vertical columns of soil that have a
salt β€œcap” at the top and found in soils of arid climates and
generally in the subsoils (B-horizon).

A

Columnar soil structure

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21
Q

What soil horizon has vertical columns of soil that might
be a few cm long and usually found in B-horizon.

A

Prismatic Soil structure

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22
Q

What soil structure has Irregular blocks that are usually 1.5 to 5.0 cm in diameter and commonly found in the B-horizon.

A

Blocky soil structure?

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23
Q

What is Sub-angular Blocky soil structure?

A

– Like blocky (Irregular blocks that are usually 1.5 to 5.0 cm in diamete) but slightly more rounded. Commonly found in
the B-horizon.

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24
Q

What is Granular soil structure?

A

Resembles cookie crumbs and is usually less than 0.5 cm in diameter. Commonly found in A-horizons
where roots have been growing.

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25
Q

How does organic matter content change soil?

A

the stability of the structure will be higher with more SOM

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26
Q

How does fungal hyphae stabilize soil?

A

Fungal hyphae are
surrounding an
aggregate like a net,
protecting individual
aggregates from
destruction.

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27
Q

What soil structure is common in sandy soils?
a) Granular
b) Columnar
c) Structureless single grain
d) Platy

A

c) Structureless single grain

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28
Q

What soil structure is commonly found in the A-horizon?
a) Granular
b) Columnar
c) Structureless single grain
d) Platy

A

a) Granular

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29
Q

What is soil consistency?

A

The soils resistance to deformation of
rupture, and degree of cohesion and
adhesion.

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30
Q

What are the four stages of soil consistence?

A

Loose, Friable, Firm, and extremely firm

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31
Q

What is the liquid limit of a soil?

A

moisture
content at which a
fine-grained soil no
longer flows like a
liquid.

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32
Q

What is the Plastic limit of a soil?

A

moisture
content at which a
fine-grained soil can no
longer be remolded
without cracking.

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33
Q

What effect does organic matter have on the soil’s color?

A

It darkens the soil.

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34
Q

What is a matrix color?

A

The dominant color in the soil

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35
Q

What is Mottling?

A

Spots or blotches of color in the soil that differ from the matrix color.

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36
Q

What are redoximorphic features?

A

Mottles that relate to the aeration, drainage, and alterations between aerobic and anaerobic of the soil.

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37
Q

What effect does manganese have on soil color?

A

Purple black to dark black

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38
Q

What effect does Hematite have on soil color?

A

Blood red

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39
Q

What effect does Goethite have on soil color?

A

Yellowish brown

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40
Q

What effect does Hydrated ferric oxide have on soil color?

A

reddish brown

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41
Q

What effect does carbonates (calcite) have on soil color?

A

Whitish

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42
Q

What effect does Glauconite have on soil color?

A

Greenish

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43
Q

What effect does Fe 3 ferric have on soil color?

A

Red or yellow

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44
Q

What effect does Fe 2 ferrous have on soil color?

A

Gray to blue

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45
Q

How does the Munell color book work?

A

Soil color is determined by comparing the color of the soil to the chips in the color charts.

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46
Q

What is soil color consist of?

A

Hue, Value, and Chroma

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47
Q

What is Hue and how is it shown in the munell color value?

A

the dominant spectral color of the rainbow - yellow, reds, orange. Shown in the 10YR part of the munell color value.

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48
Q

What is Value?

A

the relative darkness or lightness of
the soil color. Shown in the numerator of the fraction (5/).

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49
Q

What is Chroma?

A

Chroma is the relative purity or strength of the color. Intensity or saturation of the hue. Shown in the denominator of the fraction (/5)

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50
Q

What makes dark soils?

A

decomposed organic matter

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51
Q

What makes yellow soils?

A

commonly associated
with the presence or absence of iron.

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52
Q

What makes red soils?

A

Very intense weathering under well-aerated conditions cause formation of the red-colored minerals hematite (Fe2O3). The red soils in NC are also caused by oxidized iron coating around sand particles.

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53
Q

What makes Gray Soils?

A

Ferrous iron is water soluble and is lost from the soil leaving behind the gray colors primarily associated with silica.

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54
Q

What does Red, yellowish, and gray soil mean for iron?

A

Lots of iron oxide and well drained (red), some drainage (yellowish), and poorly drained (gray)

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55
Q

What are redox features?

A

Redox reactions cause fluxuations in the Fe 2 and Fe 3 levels which have different colors associated with them

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56
Q

What makes white subsoil?

A

White sub-horizons in acidic, sandy soils are often indicative of spodic conditions. Similar features might be present if
there are large accumulations of calcium, sodium or carbonates

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57
Q

The grey color of soil can indicate that the soil has iron and is not well drained.
a) True
b) False

A

A) True

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58
Q

What is bulk density?

A

Mass of a volume of undisturbed oven dry soil. Units are g/cm3 or Mg/m3
.

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59
Q

What is the bulk density equation?

A

π‘©π’–π’π’Œ π‘«π’†π’π’”π’Šπ’•π’š = π‘Ύπ’†π’Šπ’ˆπ’‰π’• 𝒐𝒇 𝑢𝒗𝒆𝒏 π‘«π’“π’š π‘Ίπ’π’Šπ’ (π’ˆ) /π‘½π’π’π’–π’Žπ’† 𝒐𝒇 π‘Ίπ’π’Šπ’ (π’„π’ŽπŸ‘)

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60
Q

What is particle density?

A

The density of solid particles only (solid phase). Units are
g/cm3 or Mg/m3

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61
Q

What is the particle density equation?

A

π‘·π’‚π’“π’•π’Šπ’„π’π’† π‘«π’†π’π’”π’Šπ’•π’š = π‘Ύπ’†π’Šπ’ˆπ’‰π’• 𝒐𝒇 𝑢𝒗𝒆𝒏 π‘«π’“π’š π‘Ίπ’π’Šπ’ (π’ˆ)/ π‘½π’π’π’–π’Žπ’† 𝒐𝒇 π‘·π’‚π’“π’•π’Šπ’„π’π’†π’” (π’„π’ŽπŸ‘)

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62
Q

What is porosity?

A

Total pore space or a measure of the soil volume that holds air and water.

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63
Q

What is the relationship between porosity and bulk density?

A

they are inversely related

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64
Q

What are macropores?

A

large pores, water drains rapidly through them due to the force of
gravity.

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65
Q

What are micropores?

A

small pores, tend to retain water so tightly, its unavailable to plants. Think about capillary action!

66
Q

What are mesopores?

A

medium-sized
pores, is the pore space where
you will find plant-available
water. Held tighter than the
force of gravity but not so tight
that plants can’t extract the
water.

67
Q

What is the porosity equation?

A

π‘ƒπ‘œπ‘Ÿπ‘œπ‘ π‘–π‘‘π‘¦ =(π‘†π‘Žπ‘‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘‘ π‘†π‘œπ‘–π‘™ π‘Šπ‘’π‘–π‘”β„Žπ‘‘ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ π‘†π‘œπ‘–π‘™ π‘Šπ‘’π‘–π‘”β„Žπ‘‘ (𝑔))/ π‘†π‘œπ‘–π‘™ π‘‰π‘œπ‘™π‘’π‘šπ‘’ (π‘π‘š3)

68
Q

How can porosity be found with bulk density and particle density?

A

π‘ƒπ‘œπ‘Ÿπ‘œπ‘ π‘–π‘‘π‘¦ = 1 βˆ’(π΅π‘’π‘™π‘˜ 𝐷𝑒𝑛𝑠𝑖𝑑𝑦 (𝑔/π‘π‘š^3)/π‘ƒπ‘Žπ‘Ÿπ‘‘π‘–π‘π‘™π‘’ 𝐷𝑒𝑛𝑠𝑖𝑑𝑦 (𝑔/π‘π‘š^3))

69
Q

What is a normal particle density?

A

2.65 g/cm^3

70
Q

Do clay soils or sandy soils have more pore space?

A

Clay soil because they have smaller and more pores

71
Q

Compaction will decrease the bulk density of a soil.
a) True
b) False

A

b) False

72
Q

As soil bulk density increases, the porosity of the soil increases.
a) True
b) False

A

b) False

73
Q

Soil consistence changes with changes in soil water content.
True or False?

A

True

74
Q

Conservation tillage can have a significant effect on transpiration of water from a rapidly growing crop of corn.
True or False

A

False

75
Q

Structure refers to the shape and size of the aggregates formed by individual particles binding into peds.
True or False

A

True

76
Q

Fungal hyphae have an important influence on soil structure because they ________.
A) create large channels that enhance water flow and aeration

B) stabilize macro aggregates

C) help to flocculate the soil colloids

D) are active in the formation of soils crusts

E) all of the above

A

B) stabilize macro aggregates

77
Q

Which type of structure is typically found in sodium-rich sub-surface horizons?

A) sub-angular blocky

B) columnar

C) platy

D) granular

E) prismatic

A

B) columnar

78
Q

Texture refers to the sizes of the individual particles that make up the soil minerals.
True or False

A

True

79
Q

Which of the following is not a textural class name?

A) silt

B) sandy silt

C) clay

D) sand

E) loam

A

B) sandy silt

80
Q

Bulk density is constant and does not change as you dig deeper into lower soil horizons.
True or False

A

False

81
Q

Soil tilth refers to ________.

A) the moisture content at which a soil is best suited for tillage

B) ratio of bulk density to particle density

C) the bearing strength of a soil under a given downward force

D) the physical suitability of a soil for plant growth

E) micro-aggregates produced as a by-product of tillage

A

D) the physical suitability of a soil for plant growth

82
Q

For any soil, the bulk density is always lower than the particle density.
True or False

A

True

83
Q

Practices that add organic matter and reduce tillage can be expected to most significantly increase the ________ in a soil.
A) total porosity

B) fineness of texture

C) macropores

D) bulk density

A

C) macropores

84
Q

Oxidized (Fe3+) iron-oxides are red whereas reduced (Fe2+) iron-oxides are gray.
True or False

A

True

85
Q

Dull gray colors are characterized by ________.

A) low chromas

B) mixed hues

C) high color values

D) gray hues

E) low color values

A

A) low chromas

86
Q

The drainage class of a soil (the degree to which the soil becomes water-saturated during the year) can be judged by the presence and location of gray colors in the soil profile.
True or False

A

True

87
Q

Tillage when the soil is excessively wet can destroy soil structure, which can increase the soil bulk density.
True or False

A

True

88
Q

The plasticity index is used to determine soil texture.
True or False

A

False

89
Q

All particles greater than 2.0 mm in diameter are collectively called silt.
True or False

A

False

90
Q

Light-colored surface soils are likely to be warmer than dark-colored surface soils if soil moisture and other conditions are the same.
True or False

A

False

91
Q

If a dry soil high in certain types of ________ is moistened, it is likely to swell up with enough force to crack pavements and building foundations.

A) iron

B) silt

C) humus

D) clay

E) any of the above

A

D) clay

92
Q

Water that plants uptake and then release back into the atmosphere is called:
a) Evaporation
b) Transpiration
c) Evapotranspiration
d) Runoff

A

b) Transpiration

93
Q

What is Cohesion?

A

the attraction of water molecules for
each other primarily due to hydrogen bonding.

94
Q

What is Adhesion?

A

the attraction of water molecules for
solid surfaces. Water adsorption to the surface of
soil via H-bonding.

95
Q

What is capillary movement?

A

the movement of water up a wick
made of hydrophilic solid materials

96
Q

The force between two water molecules is called____________, while the force between a water molecule and soil particle is called_____________.

A

Cohesion, Adhesion

97
Q

What is gravitational potential?

A

Potential energy generated by gravity pulling water down.

98
Q

What is Matric Potential?

A

Matric potential results from cohesion and adhesion. Causes negative potential (work must be done to extract water)

99
Q

What is Osmotic Potential?

A

The greater the concentration of solutes the more negative is the water potential (energy is required). Water moves toward the higher concentration to reach an equilibrium concentration. (is negative)

100
Q

When the force of gravity is smaller than the force of adhesion, the water will
stay in the soil.
True or False

A

True

101
Q

What force results from cohesion and adhesion and is a negative force (i.e., work
must be done to overcome it)?
a) Gravitational
b) Capillary
c) Matric
d) Osmotic

A

c) Matric

102
Q

What does it mean if the soil is saturated?

A

macro, meso and micro-pores
are filled with water.

103
Q

What is gravitational water?

A

The water lost from a soil following drainage due to the force of gravity. Water held in the macropores.

104
Q

What does it mean if the soil is at field capacity?

A

the amount of water a soil can hold against the pull of gravity. Where gravitational water stops draining.

105
Q

What does it mean if the soil is at wilting point?

A

water is held tight as a thin
β€œfilm” surrounding soil particles… Adhesive
forces are far greater than gravity. The water is held in the micropores.

106
Q

What does it mean if the soil is at the Hydroscopic coefficient (air-dried)?

A

Which is soil left out to dry
at room temperature.

107
Q

What is the water content of different soils at field capacity?

A

15-25% for sandy soil; 35-45% for loams; 45-50% for clay soils

108
Q

What is plant-available water?

A

water between field capacity and permanent wilting point is
plant-available water. The water is held in the mesopores.

109
Q

What is Unavailable Water?

A

water between permanent wilting point and oven dry is unavailable
water. The water is held in the micropores and unavailable for plants to use.

110
Q

How is soil moisture measured using porous block?

A

The resistance of electrodes embedded in a porous block is proportional to its water content. The wetter a block is, the lower the resistance measured across two embedded electrodes.

111
Q

How does a tensiometer used to measure soil moisture?

A

water in the tensiometer leaves through a porous end that air cannot leave through which creates a vacuum

112
Q

How does a Time Domain Reflectometry (TDR) measure soil moisture?

A

Measuring the time it takes for an electromagnetic pulse to move a few centimeters in soil. The presence of water in soil affects the speed of the electromagnetic pulse, slowing it down.

113
Q

What soil texture can hold the most water?
a) Loamy sand
b) Loam
c) Silt loam
d) Silty clay

A

d) Silty clay

114
Q

What water freely drains in the soil and is responsible for a lot of the leaching of
nutrients from soil?
a) Gravitational
b) Plant-available
c) Capillary
d) Hydroscopic

A

a) Gravitational

115
Q

Wilting point is characterized by:
a) The most amount of water a soil can hold
b) The amount of water available to plants
c) The amount of water tightly held to soil particles
d) The rate at which water moves through the soil

A

c) The amount of water tightly held to soil particles

116
Q

What pore size is plant-available water held in?
a) Macropores
b) Mesopores
c) Micropores
d) Cannot be determined with the given information

A

b) Mesopores

117
Q

How is soil water content estimated in soil?
a) Single-ring infiltrometer
b) Double-ring infiltrometer
c) Tensiometer
d) Hydrometer

A

c) Tensiometer

118
Q

What are three methods for measuring soil moisture?

A

Time Domain Reflectometry (TDR), tensiometer, porous block

119
Q

What is the equation for Gravimetric Water Content?

A

πΊπ‘Ÿπ‘Žπ‘£π‘Žπ‘šπ‘’π‘‘π‘Ÿπ‘–π‘ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘=(π‘Šπ‘’π‘‘ π‘Šπ‘’π‘–π‘”β„Žπ‘‘ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦(𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

120
Q

What is the equation for Saturated Water Content?

A

π‘†π‘Žπ‘‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘‘ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =(π‘†π‘Žπ‘‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘‘ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦(𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

121
Q

What is the Field Capacity Water Content Equation?

A

𝐹𝑖𝑒𝑙𝑑 πΆπ‘Žπ‘π‘Žπ‘π‘–π‘‘π‘¦ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =(𝐹𝑖𝑒𝑙𝑑 πΆπ‘Žπ‘π‘Žπ‘π‘–π‘‘π‘¦ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦(𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

122
Q

What is the Wilting Point Water Content equation?

A

π‘Šπ‘–π‘™π‘‘π‘–π‘›π‘” π‘ƒπ‘œπ‘–π‘›π‘‘ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ = (π‘Šπ‘–π‘™π‘‘π‘–π‘›π‘” π‘ƒπ‘œπ‘–π‘›π‘‘ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦(𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

123
Q

What is the Hygroscopic (air dry) water content?

A

π»π‘¦π‘”π‘Ÿπ‘œπ‘ π‘π‘œπ‘π‘–π‘ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =
(π΄π‘–π‘Ÿ π·π‘Ÿπ‘¦ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦(𝑔))/
𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

124
Q

What is the equation for gravitational water content?

A

πΊπ‘Ÿπ‘Žπ‘£π‘–π‘‘π‘Žπ‘‘π‘–π‘œπ‘›π‘Žπ‘™ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =
(π‘†π‘Žπ‘‘π‘’π‘Ÿπ‘Žπ‘‘π‘’π‘‘ 𝑔 βˆ’ 𝐹𝑖𝑒𝑙𝑑 πΆπ‘Žπ‘π‘Žπ‘π‘–π‘‘π‘¦ (𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

125
Q

What is the Plant-Available Water Content equation?

A

π‘ƒπ‘™π‘Žπ‘›π‘‘π΄π‘£π‘Žπ‘–π‘™π‘Žπ‘π‘™π‘’ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =
(𝐹𝑖𝑒𝑙𝑑 πΆπ‘Žπ‘π‘Žπ‘π‘–π‘‘π‘¦ 𝑔 βˆ’ π‘Šπ‘–π‘™π‘‘π‘–π‘›π‘” π‘ƒπ‘œπ‘–π‘›π‘‘ (𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

126
Q

What is the equation for Unavailable Water Content?

A

π‘ˆπ‘›π‘Žπ‘£π‘Žπ‘–π‘™π‘Žπ‘π‘™π‘’ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =
(π‘Šπ‘–π‘™π‘‘π‘–π‘›π‘” π‘ƒπ‘œπ‘–π‘›π‘‘ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔))/ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦ (𝑔)

127
Q

What are the two ways to calculate Volumetric water content?

A

VWC = GWC x Bulk Density
π‘‰π‘œπ‘™π‘’π‘šπ‘’π‘‘π‘Ÿπ‘–π‘ π‘Šπ‘Žπ‘‘π‘’π‘Ÿ πΆπ‘œπ‘›π‘‘π‘’π‘›π‘‘ =
(π‘Šπ‘’π‘‘ π‘Šπ‘’π‘–π‘”β„Žπ‘‘ 𝑔 βˆ’ 𝑂𝑣𝑒𝑛 π·π‘Ÿπ‘¦(𝑔))/ π‘‡π‘œπ‘‘π‘Žπ‘™ π‘‰π‘œπ‘™π‘’π‘šπ‘’ (π‘π‘š3)

128
Q

How do you calculate depth of water?

A

Depth of Soil x VWC = Depth of Water

129
Q

What soil will infiltrate the greatest amount of water?
a) Beach sand
b) A silt loam soil under potato production
c) A loam soil under frosted conditions
d) A compacted clay soil

A

a) Beach sand

130
Q

A soil has a platy texture, lots of micropores, and has a slow infiltration rate. What is
the soil texture?
a) Sandy
b) Silty
c) Loamy
d) Clayey

A

d) Clayey

131
Q

Drainage systems are designed to increase gas exchange between the soil and
atmosphere, so the soil can get more CO2
True or False

A

False

132
Q

What are the two categories of erosion?

A

Geological (not humans) and human-accelerated erosion

133
Q

What is the three step process for erosion?

A
  1. Detachment
  2. Transport
  3. Deposition
134
Q

What are the three types of erosion?

A

Sheet erosion, Rill erosion, and Gully erosion

135
Q

What is Sheet erosion?

A

Uniform erosion from
the entire soil surface
following detachment
due to raindrops

136
Q

What is Rill erosion?

A

The removal of soil by
concentrated water running
through little streamlets.
Rills are less than 4 inches
deep, are can be repaired
by tillage or minimal land
leveling.

137
Q

What is Gully erosion?

A

Channels deeper than 18
inches that cannot be
erased by cultivation or
simple land leveling

138
Q

What soil particle size is the most easily eroded?
a) Gravel
b) Sand
c) Silt
d) Clay

A

c) Silt

139
Q

What is the Universal Soil-loss Equation?

A

π΄π‘›π‘›π‘’π‘Žπ‘™ π‘ π‘œπ‘–π‘™ π‘™π‘œπ‘ π‘  π‘π‘’π‘Ÿ π‘Žπ‘π‘Ÿπ‘’ = 𝑅 Γ— 𝐾 Γ— 𝐿𝑆 Γ— 𝐢 Γ— 𝑃
* R = rainfall and runoff factor
* K = soil erodibility factor
* LS = slope and length factor of area
* C = cover/vegetation and management factor
* P = practices put in place to prevent erosion

140
Q

What are the 5 factors in the Universal Soil-loss Equation?

A

R = rainfall and runoff factor
* K = soil erodibility factor
* LS = slope and length factor of area
* C = cover/vegetation and management factor
* P = practices put in place to prevent erosion

141
Q

What is the Wind Erosion Prediction Equation?

A

π΄π‘›π‘›π‘’π‘Žπ‘™ π‘ π‘œπ‘–π‘™ π‘™π‘œπ‘ π‘  π‘π‘’π‘Ÿ π‘Žπ‘π‘Ÿπ‘’ = 𝑓 𝐼 Γ— 𝐢 Γ— 𝐾 Γ— 𝐿 Γ— 𝑉
– I = soil erodibility
– C = climate
– K = soil-ridge-roughness
– L = field width
– V= vegetative cover

142
Q

What are the 5 factors in the Wind Erosion Prediction Equation?

A

– I = soil erodibility
– C = climate
– K = soil-ridge-roughness
– L = field width
– V= vegetative cover

143
Q

Wind erosion is generally not affected by:
a) Soil pH
b) Soil texture
c) Soil moisture
d) Soil crusting

A

a) Soil pH

144
Q

The matric potential is due to the attraction of water molecules to soil solid surfaces.
True or False

A

True

145
Q

Which of the following means of estimating soil water levels gives a direct measurement of the water content?
A) neutron scattering
B) gravimetric determinations
C) gypsum blocks
D) tensiometer
E) pressure membrane

A

B) gravimetric determinations

146
Q

The tenacity with which water is held in soils is directly related to the soil moisture content, the higher the moisture level the greater the attraction of the water to the soil.
True or False

A

False

147
Q

Which of the following sources of water have the shortest average residence time?
A) clouds
B) oceans and ice caps
C) soil moisture
D) groundwater

A

A) clouds

148
Q

Where high-value crops or individual ornamental shrubs are to be grown and water is expensive, the most efficient type of irrigation to use would be ________.
A) furrow
B) center pivot
C) basin flooding
D) drip or trickle

A

D) drip or trickle

149
Q

The osmotic potential would likely be lowest in soils of which of the following orders?
Question 6Select one:

A. Ultisols
B. Histosols
C. Oxisols
D. Spodosols
E. Aridisols

A

E. Aridisols

150
Q

Which of the following processes are most apt to encourage good soil aeration?
A. reaction of oxygen with organic matter
B. diffusion of oxygen from the soil to the atmosphere
C. organic matter decomposition
D. creation of more macropores
E. root respiration

A

D. creation of more macropores

151
Q

Evaporation from a south-facing slope in Russia would likely be higher than from a north-facing slope.
True or False

A

True

152
Q

Land drainage is beneficial because ________.
A. it increases the availability of iron and manganese in acid soils
B. it slows down the rate of soil warming in the spring
C. it increases the water-to-air ratio in the soil pores
D. it increases the depth of root penetration in the soil
E. it increases the alternate of expansion and contraction due to freezing and thawing of soils

A

D. it increases the depth of root penetration in the soil

153
Q

At the soil moisture status β€œair dry,” water can easily be extracted by plants.
True or False

A

False

154
Q

β€œLiving” terraces involving rows of deep rooted grasses planted on the contour would be considered as contributing to which factor in the Universal soil-loss equation?
L, K, P, S, or R

A

P

155
Q

Wind erosion accounts for about what percent of the total soil erosion losses in the United States?
A. 5%
B. 20%
C. 10%
D. 75%
E. 35%

A

E. 35%

156
Q

The key to preventing soil erosion by water on both farmland and landscaping job sites is ________.
A. to grade or till the soil until a smooth surface is achieved

B. to keep the soil surface covered with vegetation

C. to keep the soil moist (with irrigation if necessary)

D. to practice good landscape sanitation by clearing away any weeds and old plant residues

E. to provide adequate surface and subsurface drainage

A

B. to keep the soil surface covered with vegetation

157
Q
A
158
Q

The universal soil-loss equation (USLE) suggests that soil erosion loss is a product of all but one of the following factors ________.
A. sloped steepness
B. soil drainage
C. vegetative cover
D. climate
E. slope length

A

B. soil drainage

159
Q

The P factor in the Universal soil-loss equation is concerned with all but one of the following ________.
A. contour tillage
B. soil erodibility
C. strip-cropping
D. terraces
E. vegetative covers

A

B. soil erodibility

159
Q

Which of the following statements about soil erosion is not true?
A. Soil erosion losses per hectare of cropped land are higher in Asia and Africa than the United States.

B. Soil erosion losses of potassium exceed those of nitrogen and phosphorus.

C. Downstream off-site costs of erosion are often higher than those in upstream fields from which the soil came.

D. The rate of soil erosion loss in the United States declined from 1980 to 1995.

E. Less than 20 percent of the total soil erosion in the United States comes from croplands.

A

E. Less than 20 percent of the total soil erosion in the United States comes from croplands.

160
Q

Conservation tillage systems are said to have all of the following advantages but one over conventional tillage systems ________.
A. it encourages higher microbial population numbers in the soil

B. it involves the use of less toxic weed control practices

C. it increases the hydraulic conductivity of the soil

D. its labor and energy requirements are lower

E. it reduces soil erosion

A

B. it involves the use of less toxic weed control practices

161
Q

The R factor of the Universal soil-loss equation is concerned with ________.
A. climate
B. residue cover on the soil
C. terraces
D. soil erodibility
E. slope steepness

A

A. climate

162
Q

A soil has been managed using a no-till system for 10 years following many years of conventional tillage operations. Which of the following changes in surface soil properties would you expect due to the no-till management system?
A. The earthworm population would decline.
B. Organic matter content would increase.
C. Bulk density would increase.
D. Soil pH would increase.
E. Aggregate stability would decline.

A

B. Organic matter content would increase.

Soil Science (2 decks)

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