Question 1

The water potential at the field capacity for most soils is in the range of -10 to -30 kPa.

Accepted Answer

A) True 
 B)False

Question 2

The following are characteristics of a water molecule.

Accepted Answer

A)  The H to O to H angle is approximately 90o C. 
B)  The two H atoms are on diametrically opposite ends of the molecule. 
C)  It has a positive and a negative side. 
D)  It is attracted to surfaces with negative but not positive charges. 
E)  It is held in soils by adhesion but not adsorption. 
A)  The H to O to H angle is approximately 90o C. 
B)  The two H atoms are on diametrically opposite ends of the molecule. 
C)  It has a positive and a negative side. 
D)  It is attracted to surfaces with negative but not positive charges. 
E)  It is held in soils by adhesion but not adsorption.

Question 3

In which of the following situations would you expect downward movement of soil water through the profile to be most rapid?

Accepted Answer

A)  uniformly textured sandy loam profile 
B)  sandy loam in upper layers with a clay band underneath 
C)  sandy loam in upper layers with a layer of coarse gravel underneath 
D)  clay texture throughout the profile 
E)  silt loam in upper layers underlain by a sandy layer 
A)  uniformly textured sandy loam profile 
B)  sandy loam in upper layers with a clay band underneath 
C)  sandy loam in upper layers with a layer of coarse gravel underneath 
D)  clay texture throughout the profile 
E)  silt loam in upper layers underlain by a sandy layer

Question 4

Osmotic and matric potentials are commonly negative because the soil water has a lower energy level than that of pure water.

Accepted Answer

A) True 
 B)False

Question 5

Water molecules have polarity primarily because each contains two H atoms and only one O atom.

Accepted Answer

A) True 
 B)False

Question 6

The property of cohesion in water stems from the attraction of water molecules for soil solids.

Accepted Answer

A) True 
 B)False

Question 7

The matric potential of soil water is _____.

Accepted Answer

A)  influenced greatly by the content of salts in the soil 
B)  not influenced appreciably by the force of gravity 
C)  is generally higher than that of pure water outside the soil 
D)  is little affected by soil solids 
E)  is lower in a sandy soil with 20 percent soil water than in a clay soil with same percentage of 
A)  influenced greatly by the content of salts in the soil 
B)  not influenced appreciably by the force of gravity 
C)  is generally higher than that of pure water outside the soil 
D)  is little affected by soil solids 
E)  is lower in a sandy soil with 20 percent soil water than in a clay soil with same percentage of

Question 8

The water content in a soil is known to be .2 m3/m3 and the potential of pure water outside the system is assumed to be 0. If the soil is a clay loam you would calculate the soil water potential (in kPa) to be

Accepted Answer

A)  0 
B)  -5 
C)  20 
D)  -20 
E)  impossible to calculate with the data given 
A)  0 
B)  -5 
C)  20 
D)  -20 
E)  impossible to calculate with the data given

Question 9

Although the total soil water content of a clay soil is about the same as a nearby well structured silt loam, the clay will likely provide more available water to plants because of its higher volume of small pores.

Accepted Answer

A) True 
 B)False

Question 10

Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the electrical resistance block?

Accepted Answer

A)  requires "destructive sampling" for each measurement 
B)  good to turn on automatic irrigation at -50 kPa 
C)  used to turn on irrigation when soil moisture potential reaches -200 kPa 
D)  would give the same reading for both a loamy sand and a silt loam if both contained 15% 
E)  both A and D 
A)  requires "destructive sampling" for each measurement 
B)  good to turn on automatic irrigation at -50 kPa 
C)  used to turn on irrigation when soil moisture potential reaches -200 kPa 
D)  would give the same reading for both a loamy sand and a silt loam if both contained 15% 
E)  both A and D

Question 11

Plant roots gain access to soil water primarily by the growth of the roots into moist soil.

Accepted Answer

A) True 
 B)False

Question 12

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

Accepted Answer

A) True 
 B)False

Question 13

Soils high in organic matter commonly hold more available water than comparable soils with lower organic matter levels. This is most likely due to what characteristics of the high O.M. soils

Accepted Answer

A)  larger micro pore space 
B)  lower permanent wilting percentage 
C)  higher field capacity 
D)  higher capacity of the O.M. to hold water tightly 
E)  higher clay content 
A)  larger micro pore space 
B)  lower permanent wilting percentage 
C)  higher field capacity 
D)  higher capacity of the O.M. to hold water tightly 
E)  higher clay content

Question 14

Unsaturated water flow _____________.

Accepted Answer

A)  is faster than saturated flow 
B)  is driven primarily by the force of gravity 
C)  is stimulated by the osmotic potential 
D)  is slower on sands than on clays if the soil moisture content is high 
E)  occurs on soils that are at field capacity 
A)  is faster than saturated flow 
B)  is driven primarily by the force of gravity 
C)  is stimulated by the osmotic potential 
D)  is slower on sands than on clays if the soil moisture content is high 
E)  occurs on soils that are at field capacity

Question 15

The osmotic potential would likely be lowest in soils of which of the following orders

Accepted Answer

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

Question 16

Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the use of a drying oven and balance?

Accepted Answer

A)  requires "destructive sampling" for each measurement 
B)  good to turn on automatic irrigation at -5.0 kPa 
C)  used to turn on irrigation when soil moisture potential reaches -20.0 kPa 
D)  gives same reading for loamy sand and silt loam if both contained 15% moisture 
E)  both A and D 
A)  requires "destructive sampling" for each measurement 
B)  good to turn on automatic irrigation at -5.0 kPa 
C)  used to turn on irrigation when soil moisture potential reaches -20.0 kPa 
D)  gives same reading for loamy sand and silt loam if both contained 15% moisture 
E)  both A and D

Question 17

Two soil samples, A & B, at different soil moisture levels are placed in contact with each other. Water will more likely move from soil A to soil B if their water potentials, expressed in kPa, are:

Accepted Answer

A)  A=-5; B=+5 
B)  A=-5; B=-5 
C)  A=-20; B=-10 
D)  A=-30; B=-40 
E)  A=-100; B=-50 
A)  A=-5; B=+5 
B)  A=-5; B=-5 
C)  A=-20; B=-10 
D)  A=-30; B=-40 
E)  A=-100; B=-50

Question 18

Gypsum or nylon electrical resistance blocks are most useful in estimating the soil water content if the soil is quite dry.

Accepted Answer

A) True 
 B)False

Question 19

The hydrogen end of a water molecule is attracted to positively charged cations such as Na+ and Ca2+.

Accepted Answer

A) True 
 B)False

Question 20

The soil water potential is a measure of the potential of a soil to hold water.

Accepted Answer

A) True 
 B)False

The water potential at the field capacity for most soils is in the range of -10 to -30 kPa.

The following are characteristics of a water molecule.

In which of the following situations would you expect downward movement of soil water through the profile to be most rapid?

Osmotic and matric potentials are commonly negative because the soil water has a lower energy level than that of pure water.

Water molecules have polarity primarily because each contains two H atoms and only one O atom.

The property of cohesion in water stems from the attraction of water molecules for soil solids.

The matric potential of soil water is _____.

The water content in a soil is known to be .2 m³/m³ and the potential of pure water outside the system is assumed to be 0. If the soil is a clay loam you would calculate the soil water potential (in kPa) to be

Although the total soil water content of a clay soil is about the same as a nearby well structured silt loam, the clay will likely provide more available water to plants because of its higher volume of small pores.

Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the electrical resistance block?

Plant roots gain access to soil water primarily by the growth of the roots into moist soil.

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

Soils high in organic matter commonly hold more available water than comparable soils with lower organic matter levels. This is most likely due to what characteristics of the high O.M. soils

Unsaturated water flow _____________.

The osmotic potential would likely be lowest in soils of which of the following orders

Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the use of a drying oven and balance?

Two soil samples, A & B, at different soil moisture levels are placed in contact with each other. Water will more likely move from soil A to soil B if their water potentials, expressed in kPa, are:

Gypsum or nylon electrical resistance blocks are most useful in estimating the soil water content if the soil is quite dry.

The hydrogen end of a water molecule is attracted to positively charged cations such as Na⁺ and Ca²⁺.

The soil water potential is a measure of the potential of a soil to hold water.

The Soils Around Us

Formation of Soils From Parent Materials

Soil Classification

Soil Architecture and Physical Properties

Soil and the Hydrologic Cycle

Soil Aeration and Temperature

The Colloidal Fraction: Seat of Soil Chemical and Physical Activity

Soil Acidity, Alkalinity, Aridity and Salinity

Organisms and Ecology of the Soil

Soil Organic Matter Overview

Nutrient Cycles and Soil Fertility

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Filters

Exam 5: Soil Water: Characteristics and Behavior

The water potential at the field capacity for most soils is in the range of -10 to -30 kPa.

The following are characteristics of a water molecule.

In which of the following situations would you expect downward movement of soil water through the profile to be most rapid?

Osmotic and matric potentials are commonly negative because the soil water has a lower energy level than that of pure water.

Water molecules have polarity primarily because each contains two H atoms and only one O atom.

The property of cohesion in water stems from the attraction of water molecules for soil solids.

The matric potential of soil water is _____.

The water content in a soil is known to be .2 m3/m3 and the potential of pure water outside the system is assumed to be 0. If the soil is a clay loam you would calculate the soil water potential (in kPa) to be

Although the total soil water content of a clay soil is about the same as a nearby well structured silt loam, the clay will likely provide more available water to plants because of its higher volume of small pores.

Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the electrical resistance block?

Plant roots gain access to soil water primarily by the growth of the roots into moist soil.

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

Soils high in organic matter commonly hold more available water than comparable soils with lower organic matter levels. This is most likely due to what characteristics of the high O.M. soils

Unsaturated water flow _____________.

The osmotic potential would likely be lowest in soils of which of the following orders

Which of the following statements concerning applications or capabilities of soil moisture measuring devices is (are) true for the use of a drying oven and balance?

Two soil samples, A & B, at different soil moisture levels are placed in contact with each other. Water will more likely move from soil A to soil B if their water potentials, expressed in kPa, are:

Gypsum or nylon electrical resistance blocks are most useful in estimating the soil water content if the soil is quite dry.

The hydrogen end of a water molecule is attracted to positively charged cations such as Na+ and Ca2+.

The soil water potential is a measure of the potential of a soil to hold water.

The Soils Around Us

Formation of Soils From Parent Materials

Soil Classification

Soil Architecture and Physical Properties

Soil and the Hydrologic Cycle

Soil Aeration and Temperature

The Colloidal Fraction: Seat of Soil Chemical and Physical Activity

Soil Acidity, Alkalinity, Aridity and Salinity

Organisms and Ecology of the Soil

Soil Organic Matter Overview

Nutrient Cycles and Soil Fertility

Practical Nutrient Management

Soil Erosion and Its Control

Soils and Chemical Pollution

Filters

The water content in a soil is known to be .2 m³/m³ and the potential of pure water outside the system is assumed to be 0. If the soil is a clay loam you would calculate the soil water potential (in kPa) to be

The hydrogen end of a water molecule is attracted to positively charged cations such as Na⁺ and Ca²⁺.