1. Soil Degradation and Conservation
Action movie

2. Soil Degradation
Land degradation is a huge problem today, especially for the world’s poor
An area equal to the size of China and India combined is now classified as having impaired biological function
Most the result of poor land management
MEDCs
Tradition of agriculture has lead to soil conserving practices
However…sometimes climate and intensive agriculture lead to devastating levels of erosion still
What about LEDCs?

4. Processes Leading to Soil Degradation
Two Types of Processes lead to soil degradation
Processes that take away soil
Mainly due to removal of vegetation
Wind and water then remove the soil
Processes that make the soil less suitable for use
Various chemicals end up in the soil and make it useless in the long run
Over fertilizing (salinization), various pollutants/pesticides

5. Human Activities Leading to Soil Degradation
Overgrazing
Too many animals graze in the same area or animals stay in the same area too long
Deforestation
Selective cutting: careful choosing each tree
Strip cutting: Cutting in rows
Clear cutting: Removing large areas of trees
Ex: In tropical regions leaves deflect and slow down rain

6. Human Activities Leading to Soil Degradation
Unsustainable agriculture
Total removal of crop after harvest
Having uncovered soil between rows
Plowing in the direction of the slope
Excessive Pesticides
Excessive irrigation (leads to salinization and erosion)
Monocultures (deplete specific nutrients)

7. Soil erosion by water Types Sheet Wash Gullying Wind erosion
Uniform loss of soil, usually when water crosses a flat field or mountainous region in a land slide
Gullying
Rivulets join to become larger, channel becomes wider and deeper, usually on steeper slopes or where water moves fast
Wind erosion
On drier exposed soils the wind continually removes topsoil

8. Soil Conservation Soil Conditioners Wind Reduction
Most common are organic materials and lime
Lime: Increases pH to counter soil acidification
Also helps clay particles stick together and act more like sand
Organics improves texture and acts as a nutrient source as well
Wind Reduction
Alley cropping/strip cropping
Soil Conserving Cultivation
Strip cropping with cover crops between rows
Terracing (create horizontal levels on slope)
Contour farming (Plow perpendicular to hillside)

9. Soil Conservation Improved Irrigation Marginal Land Crop Rotation
Limiting evaporation reduces salinization
Limiting run-off reduces erosion
Marginal Land
Accept the fact that some land is NOT suitable for farming
Crop Rotation
Some crops are hungrier than others
Rotate with a nitrogen fixer