Soils Final - Chapter 15

desertification

The spreading of desert conditions that disrupt semiarid and arid ecosystems

What is shown in the photo?

Detachment of soil particles from the soil mass

transportation of detached particles downhill

depositon of transported materials at lower elevtation

What is the cause of the stream discoloration in the image:

Sediment from a tributary stream into a larger, clean stream

What are the common negative impacts from soil erosion by water and windblown dust

a.      Cost to replace nutrients

b.      Cost to replace water

c.      Crop yield reductions from reduced soil depth

d.      Human health impacts

What does the “t-value” in a ‘Soil-Loss Tolerance’ analysis represent?

Tolerable soil loss

The maximum amount of soil that can be lost annually without degrading soils long term productivity

What are the three steps of this process, as stated in the text?

1. Detachment of soil particles from the soil mass

2. Transportation of the detached particles downhill by floating, rolling, dragging, html and splashing

3. Deposition of the transported particles at some place lower in elevation

What are these three types of erosion?

1 - sheet erosion

2 - Rill erosion

3 - Gully erosion

What is the universal soil loss formula?

Formula used to estimate the average annual soil loss from a field due to water erosion

A = RKLSCP

R = rainfall erosivity

K = soil erodibility

L = slope length

S = slope gradient or steepness

C= cover and Management

P = erosion-control practices

What is the universal soil loss formula rain related factors?

R = rainfall erosivity

What is the universal soil loss formula soil related factors?

K = soil erodibility

L = slope length

S = slope gradient or steepness

What is the universal soil loss formula Land Management factors?

C= cover and Management

P = erosion-control practices

What is ‘contour tillage’?

involves tilling and planting crops along the curves of the land rather than up and down slopes.

What is ‘ridge tillage’ and where might this technique be most effective?

planting crops on raised beds or ridges, typically with crop residue left on the soil surface.

particularly effective in areas with poor drainage, cold soils, and shorter growing seasons

What are the five basic principles of erosion control on a construction site, as described in the text?

1 - Schedule excavations activities in low rainfall periods of year

2 - Divide project into as many phases as possible

3- Cover disturbed soils as completely as possible

4 - Control the flow of runoff

5 - Trap sediment before releasing runoff

What is soil creep?

The rolling or sliding of soil and rock material along the surface of larger particles

What is Saltation?

The movement of soil by a series of short bounces along the ground surface

What are the two primary methods of minimizing wind erosion of soil?

1) Reducing wind speed at the soil surface

2) Trapping soil particles. 

What type of erosion is being shown in the image?

Gully Erosion

What type of erosion control method is being shown in the image?

Silt fence