Deck 17: Soil Erosion and Its Control

Question 1

Wind erosion accounts for about what percent of the total soil erosion losses in the United States?

A)5%
B)10%
C)20%
D)35%
E)75%

Answer 1

D

Question 2

In one field trial comparing no-till and conventional tillage,soil samples taken after 15 years without liming revealed that the pH of the upper 15 cm was lower on the no-till plot than on the conventional plot.Which of the following most likely accounts for this difference?

A)organic decomposition produced more organic acids in the no-till plot
B)earthworms were more active in the no-till plot
C)acidifying effects of nitrogen-containing fertilizers
D)Al³⁺ ions are tied up by the organic matter thereby releasing H⁺ ions
E)plowing mixes the surface soil more thoroughly

Answer 2

C

Question 3

In explaining erosion processes to a friend,which of the following would you say about accelerated erosion?

A)It refers to sediment carried by water flowing at ever greater velocity.
B)It involves a much less rapid process than geological erosion.
C)It is greatly enhanced by the splash effect of raindrops impacting bare soil.
D)It is increasing in intensity in the United States,especially in the past 10 years.
E)it removes more nitrogen from the surface soil than calcium

Answer 3

C

Question 4

Conservation tillage systems are said to have all of the following advantages but one over conventional tillage systems

A)its labor and energy requirements are lower
B)it encourages higher microbial population numbers in the soil
C)it involves the use of less toxic weed control practices
D)it increases the hydraulic conductivity of the soil
E)it reduces soil erosion

Question 5

The U.S.Department of Agriculture has developed soil-loss tolerance limits (T values)for different soils.Which of the following is the highest T value assigned for most soils in this country (Mg/ha)?

A)5.0
B)15
C)11
D)20
E)2

Question 6

Which of the USDA land use capability classes (LUC)is most suitable for the production of row crops?

A)I
B)II
C)VI
D)IV
E)VIII

Question 7

The R factor of the Universal soil-loss equation is concerned with _____.

A)soil erodibility
B)residue cover on the soil
C)terraces
D)climate
E)slope steepness

Question 8

You have been asked to produce continuous corn on five different soils using both no-till and conventional management systems.Yields on the no-till and conventional-till systems are about the same on all but one of the soils.In which of the following suborders would the poor-performing soil most likely be classified?

A)Orthods
B)Eutrox
C)Borolls
D)Udalfs
E)Xerolls

Question 9

Which of the following statements is true?

A)Sheet erosion is most obvious from a distance.
B)Gully erosion carries the most sediment away from lands in the United States.
C)Rill erosion is the most serious in forested areas.
D)Rill erosion is initiated before water concentrates in small 1-2 cm channels.
E)Rill erosion channels can be removed by ordinary cultivation.

Question 10

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)soil pH would increase
C)aggregate stability would decline
D)organic matter content would increase
E)bulk density would increase

Question 11

The revised universal soil-loss equation (RUSLE)differs from USLE in all ways but one of the following.

A)reflects the effects of raindrops striking the soil
B)accounts for seasonal changes such as freezing and thawing
C)divides the year into 15 day intervals for the cropping sequence factor
D)uses greatly modified soil erodibility factors
E)considers the effects of surface or near-surface residues at different times of the year

Question 12

Wind erosion is generally not affected by _____.

A)soil moisture
B)soil crusting
C)bulk density of the soil
D)soil pH
E)soil texture

Question 13

About what percentage of the total non-federal government owned rural lands is considered suitable for cultivation according to USDA land use capability classes (if appropriate management practices are employed)?

A)75%
B)55%
C)35%
D)20%
E)2%

Question 14

On which of the land use capability classes is suggested use restricted to non-production purposes,only wildlife and recreational purposes being appropriate?

A)I
B)II
C)VI
D)IV
E)VIII

Question 15

To be classified as a conservation tillage practice,a system must leave at least what portion of the soil surface covered with plant residues?

A)10%
B)20%
C)30%
D)40%
E)50%

Question 16

The P factor in the Universal soil-loss equation is concerned with all but one of the following:

A)contour tillage
B)strip-cropping
C)soil erodibility
D)terraces
E)vegetative covers

Question 17

"Living" 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?

A)R
B)K
C)L
D)S
E)P

Question 18

If you want to maximize the quantity of vegetative cover on soil which of the following tillage practices would you use?

A)conventional moldboard plow
B)no-tillage
C)ridge tillage
D)stubble mulch
E)strip till

Question 19

The universal soil-loss equation (USLE)suggests that soil erosion loss is a product of all but one of the following factors:

A)soil drainage
B)climate
C)slope length
D)sloped steepness
E)vegetative cover

Question 20

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)The rate of soil erosion loss in the United States declined from 1980 to 1995.
C)Downstream off-site costs of erosion are often higher than those in upstream fields from which the soil came.
D)Soil erosion losses of potassium exceed those of nitrogen and phosphorus.
E)Less than 20 percent of the total soil erosion in the United States comes from croplands.

Question 21

Slope length is generally of greater significance in determining erosion rate than is steepness of slope.

Question 22

The Revised Universal Soil-Loss Equation (RUSLE)is more site-specific,more accurate in predicting soil loss,and more quickly compares alternative procedures than does USLE.

Question 23

Conservation tillage has generally positive effects on soil physical properties.

Question 24

The effects of conservation tillage on soil erosion would be more pronounced in fields cropped continuously to corn than in fields cropped to soybean.

Question 25

Soils in Land Capability Class VIII areas are less subject to erosion than any other class.

Question 26

In the U.S.Department of Agriculture's land capability classification systems,some 15% of the Nation's cultivated land is in Class I.

Question 27

The surface soil pH is generally higher on no-tillage plots than on comparable conventionally tilled plots.

Question 28

The T values are the maximum losses of soil by erosion that can be tolerated without a reduction in the soil's long term productivity.

Question 29

Hydraulic conductivity is commonly higher in soils on which conventional tillage systems have been used than where no-tillage systems have been followed.

Question 30

Saltation is the process of wind movement of salt-affected soils from one location to another in arid regions.

Question 31

Vegetative barriers planted on the contour have been found to create low-cost "natural" terraces.

Question 32

Yields of row crops on poorly drained soils are generally somewhat higher with no-tillage systems than with conventional tillage systems.

Question 33

Ridge-till systems show promise in the management of somewhat poorly drained soils of the Midwest.

Question 34

The key to preventing soil erosion by water on both farmland and landscaping job sites is ____.

A)To keep the soil surface covered with vegetation.
B)To provide adequate surface and subsurface drainage.
C)To grade or till the soil until a smooth surface is achieved.
D)To keep the soil moist (with irrigation if necessary).
E)To practice good landscape sanitation by clearing away any weeds and old plant residues.
True/False Questions
(Write T or F after each question. )

Question 35

The soil erodibility factor in the Universal soil-loss equation (USLE)relates primarily to the soil's infiltration capacity and structural stability.

Question 36

Although transportation of soil particles in suspension in the atmosphere is very spectacular,less than 40% of the wind erosion losses generally occur in this manner.

Question 37

Conservation tillage systems are now in use on some 85% of the cropland in the USA.

Question 38

Compared to conventional tillage systems,most conservation tillage systems rely more heavily on herbicides to control weeds.

Question 39

Some 3/4 of the total soil loss from erosion in the United States is carried away by water.

Question 40

The total global soil lost through erosion is generally greater from gully erosion than from sheet erosion.

Question 41

Annual soil movement due to tillage erosion can be calculated using a simple function of the type of tillage being used and the landscape erodibility.

Question 42

In the United States,losses of soil due to wind and water erosion decreased by nearly 40% between 1982 and 2003.