1. Erosion
Daniel Volk
APES

2. What is erosion?
Material is moved from one place and transported toward another by wind or water
Deposition is the arrival of the eroded material at its new location
Both erosion and deposition are natural processes, and in the long run help create soil
Can be sometimes hard to detect (12 tons/ha = thickness of a penny)

3. Problems with Erosion
Erosion often becomes a problem for ecosystems and agriculture because it almost always occurs much more quickly than new soil is formed
Tends to remove topsoil (the most valuable soil layer for living things)
Humans have increased the vulnerability of fertile lands to erosion in 3 common ways:
Overcultivating fields due to poor planning or excessive tilling
Overgrazing and overpopulating grazing lands with more livestock than the land can support
Clearing forests on steep slopes or with large clear-cuts

4. Erosion Mechanisms
Grasslands, forests, and other plant communities help slow down erosion.
Plants and other vegetation breaks up wind, slow water flow, and holds soil into place.
Removing plants almost always accelerates erosion.
Four types of water erosion – rill, sheet, splash, gully (all more likely to occur where slopes are steeper)
Splash – raindrops dislodge soil particles that full in gaps between clumps, decreases ability absorb water
Sheet – water flows over broad surfaces in thin sheets and washes topsoil away in uniform layers
Rill – water runs along small furrows, widening and deepening them into larger channels called “rills”
Gully – cuts deeply into soil, leaving large gullies that expands as erosion continues

5. Erosion is a Global Problem
Humans are the primary cause, and have accelerated it to unnaturally high rates (human activities move 10x more soul than all other natural processes combined)
Declines in soil quality and crop yields coupled with rapid population growth in poorer, less developed countries can explain why some believe the future of agriculture will transform into a global crisis.

6. Measuring Erosion
Scientists relied on cheap, simple tools called “erosion pins”, developed in the 1960s and 70s
Spikes that can be made from almost anything are driven in the soil until their tops are level with the ground’s surface.
Over time, the surface will begin to erode and the pins will become increasingly exposes
Using more pins will result in more data over a larger range of land

7. Solutions to Erosion and Soil Degradation
Farmers can minimize erosion by intercropping, or planting different types of crops in alternating bands. This slows erosion by providing more ground cover.
Shelterbelts help reduce wind erosion. They are rows of trees or tall perennial plants that are planted along the edges of fields to slow wind.
Reduced tilling can help prevent erosion by reducing the amount of disturbance on soil. Stronger, healthier soil is less likely to easily erode when combined with other deterrents, such as shelterbelts.

8. Erosion Control Practices through Plant Cover
Farming methods that control and deter erosion integrate the general principle that maximizing plant cover will protect soils, even beyond farming.
Common to stabilize eroding water banks by planting plants to anchor the soil.
In areas where erosion is rampant, entire plantations of vast-growing trees are planted in attempt to deter soil degradation. However, although these forests help slow erosion, they do not produce ecologically functioning forests.

9. THE END