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NC State Soil Science: SSC–012: Principles of Soil Science

SSC 012 Practice Exam 3

Question #1: The primary mineral nutrients taken up by plants from the soil are

A). C, H, O
B). N,P,K
C). Ca, Mg, S

Question #2: The secondary plant nutrients are

A). C, H, O
B). N,P,K
C). Ca, Mg, S


Question #3: The plant nutrients supplied by water and air are

A). C, H, O
B). N,P,K
C). Ca, Mg, S

Question #4: Which soil material does not contribute to the cation exchange properties of the soil ?

A). silt
B). clay
C). oxides of iron and aluminum
D). colloids

Question #5: Positively charged atoms or molecules are called

A.). cations
B). anions


Question #6: Negatively charged atoms or molecules are called

A). cations
B). anions

Question #7: Which ion would be attracted and adsorbed by soil colloids?

A). NO3-
B). Ca++

Question #8: Which ion is not adsorbed by soil colloids and leaches readily from the soil?

A). NO3-
B). K+
C). A1 +++

Question #9: Adding organic matter to a soil would

A). increase the CEC
B). increase the water holding capacity
C). both of the above
D). none of the above

Question #10: The cation exchange capacity is affected by the

A). the type of clay present
B). the amount of clay
C). both of the above

Question #11: Which of the following is a 1:1 type clay mineral?

A). montomorillonite
B). quartz
C). kaolinite

Question #12: Which of the following are 2:1 type clay materials?

A). montomorillonite
B). vermiculite
C). both of the above
D). none of the above

Question #13: Which type of clay has the greatest water holding capacity?

A). kaolinite
B). montmorillonite
C). each would hold the same amount

Question #14: Which clay has the greatest capacity to shrink and swell?

A). kaolinite
B). montmorillonite

Question #15: Which clay would be stickier after adding water?

A). kaolinite
B). montmorillonite

Question #16: Which clay is sometimes used for medicinal purposes?

A). kaolinite
B). montmorillonite

Question #17: If one site has a soil; that is 50% kaolinite, and another site has a soil that is 50% montmorillonite, which would be more favorable for ease of tillage, constructing a golf course or installing a septic system

A). the site with kaolinite
B). the site with montmorillonite
C). there is no difference in the sites as far as management and land use

Question #18: Which clay listed below has the greatest CEC?

A). kaolinite
B). illite

Question #19: he charge resulting from isomorphous substitution in the structure of 2:1 clays is

A). permanent charge
B). variable charge that is pH dependent

Question #20: The charge resulting from broken chemical bonds on the edges of 1:1 clays is

A). permanent charge
B). variable charge that is pH dependent

Question #21: In soils that contain kaolinite and humus, increasing soil pH by liming

A). increases the CEC
B). decreases the CEC
C). has no effect on CEC

Question #22: A soil test indicated 6 meg/100 g of exchangeable acidity. How many milliequivalents of CaCO3 per 100 g of soil would be necessary to neutralize the acid?

A). 12
B). 6
C). 3

Question #23: How many grams of CaC03 per 100 grams of soil would be required to neutralize 6 meq of acid? (M.W. of CaC03 = 100, valence is 2)

A). 30
B). 0.3
C). 3.0

Question #24: What is the weight in grams of 6 meq. Of Al+++? (Atomic weight of Al is 27, Valence is 3)

A). .054
B). 54
C). 108

Use the following information to answer questions 25 - 27.

Cations extracted from 100 g of  soil.

			Meq./100 g

A1 +++       		5
H+               	1
Ca++          		4
Mg++			1
K+			1
Na+			0.5


Question #25: What is the CEC of the soil?

A). 6
B). 6.5
C). 12.5

Question #26: What is the percent base saturation of the soil?

A). 52%
B). 48%

Question #27: What is the percent exchangeable acidity?

A). 48%
B). 32%

Question #28: Soil pH is a measure of the

A). Hydrogen ion concentration
B). Aluminum ion concentration
C). The percent base saturation

Question #29: When soil pH is measured in water, it is a measure of the

A). active acidity
B). potential acidity
C). active and potential acidity

Question #30: Aluminum ions are the major part of the ______ in soils

A). active acidity
B). potential acidity

Question #31: An effect of soil acidity that is detrimental to plant growth is

A). aluminum toxicity
B). hydroxide toxicity

Question #32: Buffer capacity of soils refers to

A). the clay minerals in soils used in medicines
B). resistance to change in pH
C). the amount of water held by soils

Question #33: Which soils has the greatest buffer capacity?

A). sandy loam
B). clay loam (montmorillonite clay)
C). clay loam (kaolinite clay)

Question #34: Aluminum ions in soils cause a lower pH (more acid) because

A). the Al+++ reacts with water to produce H+ ions
B). the Al+++ reacts with water to produce OH‑ ions

Question #35: The amount of lime that must be applied to increase the soil pH from 4.5 to 5.8 would be greatest for a

A). clay loam
B). sand
C). There is no difference in the amount of lime required since the pH change is the same

Question #36: To maintain the pH around 5.8 lime would have to be applied more often on the

A). clay loam
B). sand
C). There is no difference in the frequency

Question #37: A liming material neutralizes acidity by producing

A). H+ ions
B). OH- ions
C). Al+++ ions

Question #38: Decomposition of organic matter

A). increases soil pH (makes it less acid)
B). decreases soil pH (makes it more acid)
C). has no affect on soil acidity

Question #39: Applying ammonium fertilizers to soil causes the soil

A). to eventually become more acid
B). to eventually become less acid
C). applying fertilizer does not affect pH

Question #40: Which of the following is not a liming material?

A). calcium carbonate
B). calcium hydroxide
C). calcium oxide
D). calcium sulfate

Question #41: What is the molecular weight of Ca (OH)2? (atomic weights Ca=40, 0=16, H=1)

A). 74
B). 26
C). 52

Question #42: What is the neutralizing value (calcium carbonate equivalent) of Ca(OH)2?

A). 119%
B). 74%
C). 135%

Question #43: Which liming material is a source of magnesium?

A). calcitic limestone
B). dolomitic limestone
C). calcium hydroxide

Question #44: Which liming material should be used if a quick pH adjustment is needed?

A). calcitic limestone
B). dolomitic limestone
C). calcium hydroxide

Question #45: The quality and effectiveness of a liming material is affected by its

A). purity
B). fineness and calcium carbonate equivalent
C). all of the above
D). none of the above

Question #46: The most effective method of lime application before turf is planted is

A). thorough mixing with the soil
B). surface application

Question #47: In a lab test, a moist soil sample was divided into two equal parts. One gram of calcium oxide was applied to one portion and one gram of dolomitic limestone was added to the other. After 1 week the pH would be higher

A). in the sample with dolomitic limestone
B). in the sample with calcium oxide
C). the pH would be the same

Question #48: Which soil amendment could be applied to make soil more acid?

A). dolomitic limestone
B). elemental sulfur
C). calcium hydroxide

Question #49: Cation exchange capacity affects

A). the amount of plant nutrients soil can hold
B). how often lime must be applied
C). both of the above

Question #50: The main effect of high soil salinity on plant growth is that

A). It is more difficult for plants to take up water from saline soils
B). plants take up excess amounts of water from saline soils
C). soil salinity does not affect plant growth


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