Transcript Powerpoint

Soil Erosion
1
Bird City, Kansas
2
3
St. Francis, Kansas
4
5
6
7
8
San Luis Valley, Colorado
9
10
11
12
13
Al Asad, Iraq
14
15
16
17
18
The Dustbowl
19
How much soil is lost?

5 Billion Tons, Billion with a
“B” lost each year

3.5 Billion tons due to Water

1.5 Billion tons due to Wind
20
What is average loss?

Scientists expect to lose 5 tons per acre per
year





This much can be re-captured through soil
formation
Water makes up 4.8 tons lost
Wind makes up 3.3 tons lost
8.1 tons is average
THIS IS TOO MUCH!
21
Lasting effects of erosion







Loss of topsoil-loss of
productive organisms
Organic matter gone along
with N-P-K
Reduced Root Zone-less
water holding capacity
Gullies make farming
difficult
Pollutes lakes, streams
causing harm to wildlife
Sediment fills up lakes,
streams, and waterways
Loss of $$$$ due to unproductive soil
Sediment fills and pollutes a lake
22
What affects erosion

#1 Texture and Structure

The coarser the texture, the higher infiltration rate,
the lower amounts of run-off

Fine particles detach easier than large particles


Silt erodes faster than sand
Good structures resist rain splash and wind lift
23
What affects erosion

#2 Slope

Length and steepness or grade both need considered

Length accounts for volume of erosion

Grade creates water velocity

Long fields have snowball effect with wind

Little loss at the head end, piles of soil at the bottom end
24
What affects erosion

#3 Surface Roughness
Rough soil slows water
and reduces downhill flow


Tillage ridges are helpful

Tillage across slope prevents erosion, tillage with the slope
promotes erosion
25
What affects erosion

#4 Surface Cover



Surface cover reduces
impact from falling
water and slows down
movement of water
Surface crops’ roots
hold soil closely
Row crops need a foliage
canopy to help protect
soil
26
What affects erosion

#5 Climate

Dry soils and dry
climates promote wind
erosion

The drier the soil
particles the greater risk
of being picked up and
moved elsewhere

Dry weather promotes
wind loss
27
Types of erosion

#1 Splash Erosion

Water hits the soil and
can move particles as
much as 5 feet!
28
Types of erosion

#2 Sheet erosion

A thin layer of soil is
removed as a sheet.

Sheet erosion hides until
topsoil is lost and subsoil
is exposed.
Sheet erosion exposes sub-soil in the circles
29
Types of erosion

#3 Rill erosion

Many small channels on
slopes

Running water carves
out rills

Still can be filled in by
tillage
30
Types of erosion

#4 Ephemeral (e fem er al)



Large rills
Tillage won’t completely fill
them in
The next rain will create
gullies if not fixed
31
Types of erosion

#5 Gully erosion

So large equipment
cannot cross

Begin on steep slopes
where water creates
enough energy to cut
large channels in the
earth
32