SSC 200 EXAM 2 QUESTIONS & ANSWERS
Universal Soil-loss Equation (USLE): A=RKLSCP - Answer -A=Predicted loss
(tons/acre)
R=Climate erosivity
K=Soil erodibility
L=Slope length
S=Slope gradient or steepness
C=Cover and management
P=Erosion control practices
Wind Erosion Prediction equation (WEQ): E=F(ICKLV) - Answer -E=Predicted wind
erosion
I=Soil erodibility
L=Field width
K=Soil-ridge-cover
V=Vegetative cover
C=Climate
Water content-Gravimetric - Answer -W=Mass(water)/Mass(oven dry soil)
Water content-Gravimetric cont. - Answer -SWC=S soil(g)-OD soil(g)/OD(g)
FCWC=FC(g)-OD(g)/OD(g)
WPWC=WP(g)-OD(g)/OD(g)
HWC=AD(g)-OD(g)/OD(g)
GWC=S soil(g)-FC(g)/OC(g)
PAWC=FC(g)-WP(g)/OD(g)
Soil-loss tolerance - Answer --Some soil erosion can be tolerated without degrading soil
quality
-Specific soil loss tolerance limits: T-values
-11 Mg/ha is the maximum T-value
-Assumed that productive capacity of soil can be maintained if soil loss is less than soil's
T-value
Types of erosion: - Answer --Sheet erosion
-Rill erosion
-Gully erosion
Sheet erosion - Answer --Uniform erosion from entire soil surface
, -Erosion rates are enhanced by the splash effects of raindrops
Rill eroison - Answer -Involves tiny channels (rills) in which water tends to concentrate
as it runs off the soil
Gully erosion - Answer --Deep channels that cannot be erased by cultivation or simple
land leveling
-Although looks more catastrophic and is locally destructive, by far most soil is lost by
sheet and rill erosion
Erosion control practices - Answer --Cover crop management
-Terraces
-Soil stabilization
Cover crop management - Answer --Contour Planting: Alternating strips with high-
residue cover or perennial crops
-Terraces-Control slope steepness
In explaining erosion processes to a friend, which of the following would you say about
accelerated erosion? - Answer -It is greatly enhanced by the splash effect of raindrops
impacting bare soil.
The universal soil-loss equation (USLE) suggests that soil erosion loss is a product of
all but one of the following factors: - Answer -a. sloped steepness
b. climate
c. vegetative cover
d. soil drainage CORRECT
e. slope length
Compared to conventional tillage systems, most conservation tillage systems rely more
heavily on herbicides to control weeds. - Answer -True
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? - Answer -organic matter
content would increase
Slope length is generally of greater significance in determining erosion rate than is
steepness of slope. - Answer -False
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. - Answer -True
Vegetative barriers planted on the contour have been found to create low-cost "natural"
terraces. - Answer -True
Universal Soil-loss Equation (USLE): A=RKLSCP - Answer -A=Predicted loss
(tons/acre)
R=Climate erosivity
K=Soil erodibility
L=Slope length
S=Slope gradient or steepness
C=Cover and management
P=Erosion control practices
Wind Erosion Prediction equation (WEQ): E=F(ICKLV) - Answer -E=Predicted wind
erosion
I=Soil erodibility
L=Field width
K=Soil-ridge-cover
V=Vegetative cover
C=Climate
Water content-Gravimetric - Answer -W=Mass(water)/Mass(oven dry soil)
Water content-Gravimetric cont. - Answer -SWC=S soil(g)-OD soil(g)/OD(g)
FCWC=FC(g)-OD(g)/OD(g)
WPWC=WP(g)-OD(g)/OD(g)
HWC=AD(g)-OD(g)/OD(g)
GWC=S soil(g)-FC(g)/OC(g)
PAWC=FC(g)-WP(g)/OD(g)
Soil-loss tolerance - Answer --Some soil erosion can be tolerated without degrading soil
quality
-Specific soil loss tolerance limits: T-values
-11 Mg/ha is the maximum T-value
-Assumed that productive capacity of soil can be maintained if soil loss is less than soil's
T-value
Types of erosion: - Answer --Sheet erosion
-Rill erosion
-Gully erosion
Sheet erosion - Answer --Uniform erosion from entire soil surface
, -Erosion rates are enhanced by the splash effects of raindrops
Rill eroison - Answer -Involves tiny channels (rills) in which water tends to concentrate
as it runs off the soil
Gully erosion - Answer --Deep channels that cannot be erased by cultivation or simple
land leveling
-Although looks more catastrophic and is locally destructive, by far most soil is lost by
sheet and rill erosion
Erosion control practices - Answer --Cover crop management
-Terraces
-Soil stabilization
Cover crop management - Answer --Contour Planting: Alternating strips with high-
residue cover or perennial crops
-Terraces-Control slope steepness
In explaining erosion processes to a friend, which of the following would you say about
accelerated erosion? - Answer -It is greatly enhanced by the splash effect of raindrops
impacting bare soil.
The universal soil-loss equation (USLE) suggests that soil erosion loss is a product of
all but one of the following factors: - Answer -a. sloped steepness
b. climate
c. vegetative cover
d. soil drainage CORRECT
e. slope length
Compared to conventional tillage systems, most conservation tillage systems rely more
heavily on herbicides to control weeds. - Answer -True
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? - Answer -organic matter
content would increase
Slope length is generally of greater significance in determining erosion rate than is
steepness of slope. - Answer -False
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. - Answer -True
Vegetative barriers planted on the contour have been found to create low-cost "natural"
terraces. - Answer -True
