Soil erosion is a major problem in parts of Africa like Guinea and Zimbabwe. The overuse of land for farming and grazing has removed vegetation that holds soil in place. Heavy rainfall then washes away topsoil, reducing the fertility of the land. This makes it difficult for farmers to grow food, potentially leading to hunger, poverty, and migration. Some efforts to prevent soil erosion include planting trees, using vetiver grass, and constructing stone terraces across slopes.

1. Preventing Soil Erosion

2. What is erosion?
Erosion is the process by which rocks and
soil are transported from one location to
another.
The material moved by erosion is called
sediment

3. What causes erosion?
• Gravity pulls everything to the center of
the Earth
• Gravity causes sediment, water and other
material to move downhill, causing
mudflows or landslides.

4. Mudflow Landslide

5. What causes erosion?
• Moving water is
the main cause of
erosion
• As water moves
over the land, it
carries sediment
with it. This
moving water is
called run-off

6. The effects of soil erosion
• Soil erosion is a major problem when you
are trying to farm on a steep slope.
• Gravity and water cause the surface of the
soil to fall down slope away from farming
plots.
• The surface of the soil is called topsoil.

7. The effects of soil erosion
• Topsoil is rich in
nutrients that plants
need to grow.
• Runoff removes the
topsoil from the
farmland making it
difficult to grow
healthy plants.

8. The effects of soil erosion
• Removing
vegetation (grass,
trees etc.) from
the land will
increase soil
erosion.
• The roots helps
absorb water and
traps sediment
from flowing away.

9. Africa and Soil Erosion
• Soil erosion in Guinea
•Soil erosion
in Zimbabwe

10. Africa and Soil Erosion
• drought and then an intense rainy season
causes wide spread soil erosion issues (3
to 4 cm/hour) (http://www.public.asu.edu/~mschmeec/rainsplash.html)

11. Africa and Soil Erosion
•Overgrazing of livestock
•Over-ploughing of farmland
•Global warming – dry lands are more
vulnerable
•Wind erosion in dry flat areas
•Slash and burn agriculture – too much bare
soil
•Poor – depend on Africa’s natural resources
for survival – exploit and overuse the land as
situation worsens

13. Desertification
Desertification -Process by which a
geographic region becomes a desert. The
change may result from natural changes in
climate or by human activity

15. Effects of Soil Erosion in Africa
•Widespread hunger and poverty
•Food riots – violence, political instability
•Less educated youth
•Migrating farmers – border conflict
•Plant loss – leads to widespread flooding
•Annual income lost in areas affected by
desertification = $ 42 billion (World Bank)
•From 1997 – 2000, 60 million moved from
Sub-Saharan Africa

16. African Farmers Face Critical Loss of Fertile Land
by Jason Beaubien
NPR Podcast
April 27, 2006

17. Preventing Soil Erosion
• Reforestation –
when farmland is
planted with trees
to return it to its
original forested
condition to
control erosion

18. Preventing Soil Erosion
• Composting – fertilize the soil with organic
matter

19. Preventing Soil Erosion
• Contouring – planting crops across the
slope to prevent erosion

20. Preventing Soil Erosion
• Interseeding –
growing a cover crop
into a standing cash
crop

21. Preventing Soil Erosion
• Vetiver grass – roots grow 2-4 meters
downward, forms tight clumps

23. by Christopher Thomas, Masonga/Samhutsa, Zimbabwe
Over the years, the population of the Masonga area has increased and
farmers here have begun using for farming more and more of the
woodlands that are a part of the catchment area of the Tamganda and
Nyamtikwa rivers. The woodlands are located in very hilly areas; as
more and more trees are removed for agriculture, soil erosion has
increased. To prevent soil erosion, farmers have erected stone contour
ridges, or terraces. Some of them have planted a grass along them
indigenous to Mozambique, called vetiver grass. But soil erosion is still
a problem in the area, especially in gardens planted along the rivers.
Soil erosion not only makes it harder for farmers to grow crops, but it
also makes the water of the Tanganide and Nyamtikwa rivers less
pure. The local farmers, led by the agricultural officer and the district
natural resource conservation group, have begun to address the
problem by planting more and more vetiver grass each year and by
replacing highly cultivated riverside gardens with fruit tree plantations,
which require much less cultivation and cause less soil erosion.

24. Terracing