Basic Soil

Question 1

Which of the following describes clay particle properties?

A) hard to erode but easily carried as runoff
B) easy to erode and easily carried as runoff
C) hard to erode and hard to be carried as runoff
D) easy to erode and hard to be carried as runoff

Answer 1

A.). High clay soils are more resistant to detachment, but once detached are easily transported and suspended in solution

(Module 2 / Page 16)

Question 2

What role does organic material play in the structure of soil? Organic material makes soils…

Answer 2

organic material makes soil…

MORE permeable and MORE stabile

(Module 2 / Page 16)

Question 3

Soils with what types of particles have the HIGHEST erodibility?

Answer 3

Silt particles and fine sands

Module 2 / Page 16

Question 4

Clay soils are resistant to detachment but what negative might they have on a construction site?

Answer 4

Clay soils have poor infiltration which will increase runoff

Module 2 / Page 17

Question 5

What is a “k-factor” used to describe?

Answer 5

K-factors can be used to describe how susceptible the soil is to erosion.

(Module 2 / Page 18)

Question 6

Slope steepness influences erodibility. What slope gradient constitutes a steep slope and a HIGH erosion hazard?

Answer 6

15% and over is considered a high erosion hazard.

Module 2 / Page 18

Question 7

What is the difference between convex slopes and concave slopes?

Answer 7

Convex slope means steeper at the lower end.
Concave slopes flatten at the lower end.

(Module 2 / Page 19)

Question 8

Between convex and concave slopes, which has the higher potential for erosion?

Answer 8

Convex slopes have a higher potential for erosion

Module 2 / Page 19

Question 9

A slope has a length of 100’ and a 4% slope. Do these criteria constitute a critical erosion hazard?

Answer 9

No.

With a slope between 0-7%, it would require a length of 300 ft or more to constitute a critical erosion hazard.

(Module 2 / Page 19)

Question 10

What is the most important factor to minimize erosion?

Answer 10

Maintaining surface cover

Module 2 / Page 20

Question 11

How effective is permanent grass at reducing soil erosion? (Provide a percentage)

Answer 11

permanent grass reduces soil erosion by 99%

Module 2 / Page 20

Question 12

How effective is mulch/wood chips/ wood cellulose fiber at reducing soil erosion? (Provide a percentage)

Answer 12

Wood chips and similar mulching materials are usually 90% effective.

(Module 2 / Page 20)

Question 13

What may be some soil properties used to develop a K factor?

Answer 13

• Permeability
• Particle Size Distribution
• Organic Matter content
• Soil structure

(Module 2 / Page 16)

Question 14

What is the range of slope gradients that are considered low erosion hazards? What is the range that is considered moderate erosion hazards?

Answer 14

0-7 % is considered LOW

7-15% is moderate and above 15% is high

(Module 2 / Page 18)

Question 15

Would a slope of 13% gradient and 400 feet in length be considered a critical erosion hazard?

Answer 15

Yes. Between 7 and 15% any slope longer than 150’ would be considered a critical erosion hazard.

(Module 2 / Page 19)

Question 16

What effect can freezing temperatures have on soil?

Answer 16

Freezing temperatures can destroy the soil structures and destabilize the soil when water in the soil expands.

(Module 2 / Page 15)

Question 17

What effect(s) can wind have on a soil?

Answer 17

Wind can dry out a soil and reduce cohesiveness.

Module 2 / Page 15

Question 18

What effect(s) can warm weather have on soil?

Answer 18

Warm temperatures can bake the soil and this can destroy the soil structure.

(Module 2 / Page 15)

Question 19

What is permeability?

Answer 19

The rate at which water will move through the soil.

Module 2 / Page 17

Question 20

In relation to soil, what does “bulk density” mean?

Answer 20

How tightly soil particles are packed together.

Module 2 / Page 15

Question 21

What equation describes long-term average soil losses expected from sheet and rill erosion for agricultural land use and is able to illustrate how implementation of ESC measures may reduce erosion potential?

Answer 21

The Universal Soil Loss Equation or USLE

Module 2 / Page 30

Question 22

Describe what K-factor values represent low erodibility, moderate erodibility, and high erodibility.

Answer 22

0. 23 and lower is considered low erodibility
1. 24 to 0.36 is considered moderate erodibility
2. 36 and higher is considered high erodibility

(Module 2 / Page 18)