Question 1

In humid regions repeat applications of limestone are needed after a few years primarily because of ____.

Accepted Answer

A)  the release of aluminum ions from the structure of silicate clays
B)  the annual loss of calcium and magnesium in drainage waters
C)  increases in soil acidity from acid rain
D)  increased rates of formation of carbonic acid (H2CO3) 
E)  increases in phosphate fertilizationF) C) and D)
G) A) and E)

Question 2

How does the amount of lime needed to neutralize the residual acidity in a clay loam soil compare to that needed to neutralize the active acidity in that soil?

Accepted Answer

A)  residual requires considerably less
B)  residual requires about the same
C)  residual requires about double
D)  residual requires 10 times greater
E)  residual requires 5,000 times greaterF) A) and E)
G) None of the above

Question 3

The drainage of some coastal wetland soils results in high pH due to underlying lime deposits.

Accepted Answer

A) True 
 B)False

Question 4

A soil has a maximum potential cation exchange capacity of 30 cmolc/kg and has a 50% acid saturation.If you want to decrease the percentage acid saturation to 10%, how many cmolc of calcium would it take to replace the exchangeable acid cations per kg of soil? Assume all the calcium exchanged with aluminum.

Accepted Answer

A)  30
B)  40
C)  6
D)  12
E)  5F) A) and E)
G) B) and D)

Question 5

Active soil acidity is a measure of the H+ ion activity in the soil solution.

Accepted Answer

A) True 
 B)False

Question 6

If you want to grow azaleas in a soil that initially has a pH of 6.5 and have been told that you should apply sulfur to reduce the soil pH, you would likely need more sulfur if the soil is a clay Vertisol than if it is an clay Ultisol.

Accepted Answer

A) True 
 B)False

Question 7

The higher the cation exchange capacity of a soil, the greater is its buffer capacity.

Accepted Answer

A) True 
 B)False

Question 8

The ill effects of acidity in subsoils can be ameliorated by adding gypsum (CaSO4-2H2O)  to the soil surface.Which of the following most likely helps account for this effect?

Accepted Answer

A)  The gypsum replaces hydrogen from colloids which moves down the profile and decreases the pH of the subsoil layers.
B)  Calcium from the gypsum replaces hydrogen from colloids in the subsoil thereby increasing the soil pH.
C)  Gypsum dissolves and leaches downward, increasing the Ca/Al ratio in the soil solution in subsoil layers.
D)  Sulfate ions from the gypsum react with H ions in the subsoil to form H2SO4.
E)  Gypsum stimulates root growth in the surface soil horizons.F) B) and D)
G) C) and E)

Question 9

Assume you want to grow azaleas in a soil with a pH of 6.0.The application of which of the following would be most appropriate to make this soil suitable for this ornamental?

Accepted Answer

A)  chicken manure
B)  limestone
C)  elemental sulfur
D)  iron oxide
E)  hydrated limeF) A) and B)
G) B) and E) C

Question 10

Nitrogen fertilization is a significant cause of acidity in many cultivated soils.

Accepted Answer

A) True 
 B)False

Question 11

Which of the following trees would you expect to fare most poorly in a soil at pH 5.0?

Accepted Answer

A)  loblolly pine
B)  aspen
C)  sumac
D)  walnut
E)  white spruceF) B) and C)
G) All of the above

Question 12

The amount of exchangeable acidity is much smaller than the residual acidity.

Accepted Answer

A) True 
 B)False

Question 13

In extremely acid soils (pH 3.0 to 4.0) most of the Al3+ and H+ ions are bound tightly by organic matter and silicate clays and are not readily exchangeable.

Accepted Answer

A) True 
 B)False

Question 14

Phosphorus availability in acid soils is constrained by the presence of significant quantities of reactive ______.

Accepted Answer

A)  iron
B)  calcium
C)  magnesium
D)  sulfur
E)  boron.F) C) and E)
G) None of the above

Question 15

Which of the following human actions is most apt to result in a long term increase in soil pH?

Accepted Answer

A)  application of NH4- containing fertilizers
B)  application of farm manure
C)  irrigation with high sodium salt-containing waters
D)  emission of gases from automobiles
E)  application of unlimed sewage sludgeF) A) and E)
G) C) and E)

Question 16

Iron and manganese are commonly deficient in very acid soils.

Accepted Answer

A) True 
 B)False  False

Question 17

Which of the following would likely grow best on a soil with a pH of 6.0?

Accepted Answer

A)  alfalfa
B)  sweet clover
C)  tomatoes
D)  blueberries
E)  cranberriesF) D) and E)
G) C) and D) C

Question 18

An acid soil is known to contain toxic quantities of a certain plant nutrient.Which of these essential elements is it most likely to be?

Accepted Answer

A)  nitrogen
B)  manganese
C)  phosphorus
D)  molybdenum
E)  boronF) B) and E)
G) B) and C)

Question 19

Soil reaction indicates the degree of acidity or alkalinity in a soil.

Accepted Answer

A) True 
 B)False

Question 20

Among the soils of which order would you most likely find the highest buffering capacities?

Accepted Answer

A)  Alfisols
B)  Vertisols
C)  Oxisols
D)  Spodosols
E)  UltisolsF) A) and B)
G) A) and C)

Exam 9: Soil Acidity

In humid regions repeat applications of limestone are needed after a few years primarily because of ____.

Correct Answer
verified

How does the amount of lime needed to neutralize the residual acidity in a clay loam soil compare to that needed to neutralize the active acidity in that soil?

Correct Answer
verified

The drainage of some coastal wetland soils results in high pH due to underlying lime deposits.

Correct Answer
verified

Correct Answer
verified

Active soil acidity is a measure of the H⁺ ion activity in the soil solution.

Correct Answer
verified

If you want to grow azaleas in a soil that initially has a pH of 6.5 and have been told that you should apply sulfur to reduce the soil pH, you would likely need more sulfur if the soil is a clay Vertisol than if it is an clay Ultisol.

Correct Answer
verified

The higher the cation exchange capacity of a soil, the greater is its buffer capacity.

Correct Answer
verified

The ill effects of acidity in subsoils can be ameliorated by adding gypsum (CaSO₄^-2H₂O) to the soil surface.Which of the following most likely helps account for this effect?

Correct Answer
verified

Assume you want to grow azaleas in a soil with a pH of 6.0.The application of which of the following would be most appropriate to make this soil suitable for this ornamental?

Correct Answer
verified
C

Nitrogen fertilization is a significant cause of acidity in many cultivated soils.

Correct Answer
verified

Which of the following trees would you expect to fare most poorly in a soil at pH 5.0?

Correct Answer
verified

The amount of exchangeable acidity is much smaller than the residual acidity.

Correct Answer
verified

In extremely acid soils (pH 3.0 to 4.0) most of the Al³⁺ and H⁺ ions are bound tightly by organic matter and silicate clays and are not readily exchangeable.

Correct Answer
verified

Phosphorus availability in acid soils is constrained by the presence of significant quantities of reactive ______.

Correct Answer
verified

Which of the following human actions is most apt to result in a long term increase in soil pH?

Correct Answer
verified

Iron and manganese are commonly deficient in very acid soils.

Correct Answer
verified
False

Which of the following would likely grow best on a soil with a pH of 6.0?

Correct Answer
verified
C

An acid soil is known to contain toxic quantities of a certain plant nutrient.Which of these essential elements is it most likely to be?

Correct Answer
verified

Soil reaction indicates the degree of acidity or alkalinity in a soil.

Correct Answer
verified

Among the soils of which order would you most likely find the highest buffering capacities?

Correct Answer
verified

Exam 9: Soil Acidity

In humid regions repeat applications of limestone are needed after a few years primarily because of ____.

Correct AnswerverifiedShow Answer

How does the amount of lime needed to neutralize the residual acidity in a clay loam soil compare to that needed to neutralize the active acidity in that soil?

Correct AnswerverifiedShow Answer

The drainage of some coastal wetland soils results in high pH due to underlying lime deposits.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Active soil acidity is a measure of the H+ ion activity in the soil solution.

Correct AnswerverifiedShow Answer

If you want to grow azaleas in a soil that initially has a pH of 6.5 and have been told that you should apply sulfur to reduce the soil pH, you would likely need more sulfur if the soil is a clay Vertisol than if it is an clay Ultisol.

Correct AnswerverifiedShow Answer

The higher the cation exchange capacity of a soil, the greater is its buffer capacity.

Correct AnswerverifiedShow Answer

The ill effects of acidity in subsoils can be ameliorated by adding gypsum (CaSO4-2H2O) to the soil surface.Which of the following most likely helps account for this effect?

Correct AnswerverifiedShow Answer

Assume you want to grow azaleas in a soil with a pH of 6.0.The application of which of the following would be most appropriate to make this soil suitable for this ornamental?

Correct AnswerverifiedC

Nitrogen fertilization is a significant cause of acidity in many cultivated soils.

Correct AnswerverifiedShow Answer

Which of the following trees would you expect to fare most poorly in a soil at pH 5.0?

Correct AnswerverifiedShow Answer

The amount of exchangeable acidity is much smaller than the residual acidity.

Correct AnswerverifiedShow Answer

In extremely acid soils (pH 3.0 to 4.0) most of the Al3+ and H+ ions are bound tightly by organic matter and silicate clays and are not readily exchangeable.

Correct AnswerverifiedShow Answer

Phosphorus availability in acid soils is constrained by the presence of significant quantities of reactive ______.

Correct AnswerverifiedShow Answer

Which of the following human actions is most apt to result in a long term increase in soil pH?

Correct AnswerverifiedShow Answer

Iron and manganese are commonly deficient in very acid soils.

Correct AnswerverifiedFalse

Which of the following would likely grow best on a soil with a pH of 6.0?

Correct AnswerverifiedC

An acid soil is known to contain toxic quantities of a certain plant nutrient.Which of these essential elements is it most likely to be?

Correct AnswerverifiedShow Answer

Soil reaction indicates the degree of acidity or alkalinity in a soil.

Correct AnswerverifiedShow Answer

Among the soils of which order would you most likely find the highest buffering capacities?

Correct AnswerverifiedShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Active soil acidity is a measure of the H⁺ ion activity in the soil solution.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

The ill effects of acidity in subsoils can be ameliorated by adding gypsum (CaSO₄^-2H₂O) to the soil surface.Which of the following most likely helps account for this effect?

Correct Answer
verified

Correct Answer
verified
C

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

In extremely acid soils (pH 3.0 to 4.0) most of the Al³⁺ and H⁺ ions are bound tightly by organic matter and silicate clays and are not readily exchangeable.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
False

Correct Answer
verified
C

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified