1. What you think of when you hear “natural resources.”
Definition?
Examples?
Importance?

2. Natural Resource: Anything in the environment that humans use.
Usually in limited quantity
Not human made

3. Fertile Soil: One of Earth’s most underrated natural resources.
Everything that lives on land depends directly or indirectly on soil to survive.
Examples?

4. Fertile Soil: <1/8 of Earth’s lands are fertile for plant growth
“Sod”
Tough roots
At soil surface

5. Fertile Soil 100’s of years for cm’s of soil to form
1000’s of years for Mn farmland to develop
Prairies spreading from Kansas to MN were some of the most fertile soils.

6. Soil Damage:
Soil value is reduced when the topsoil is removed by erosion.
Soil becomes “Exhausted.”

7. Soil Damage: South in 1800’s Cotton only farms abandoned
George Washington Carver
1920’s
Plant roots
Nitrogen
Revived by growing peanuts

8. Soil Damage: Plants protect topsoil from erosion and damage
Due to
Excess rainfall
Drought
Soil Erosion helped lead to
Dust Bowl of the 1930’s
Government encouraged methods of soil conservation in farming

9. Soil Conservation:
Methods to manage the destruction of topsoil, keeping it fertile.
1. Contour Plowing:
Plow following the natural curves of land
Slows excess rain runoff

10. Soil Conservation: 2. Conservation Plowing:
Farmers touch the soil as little as possible
No tilling/cleaning after harvest
Soil keeps nutrients and moisture

11. Soil Conservation: 3. Crop Rotation:
Farmers change the crop grown in fields each year
Rotating nutrients used and nutrients added to the soil
Ex:
Year 1: Corn is nutrient stealing
Year 2: Oats low nutrient need
Year 3: Soybeans restore nutrients

12. Soil! It’s not dirt.

13. How many different layers do you see?
“Horizons”

14. How many different particles do you see?

15. Soil: Mixture of: Loose material in which plants can grow Rock pieces
Mineral pieces
Hummus
Decaying organic material
Water and air
Loose material in which plants can grow

16. Soil Fertility The measure of how well soil supports plant life
Nitrogen
Sulfur
Phosphorus
Potassium
More hummus = more fertile

17. Soil Texture Gravel Sand Silt Depends of the size of particles Clay
1/256 mm
Dense and heavy
Holds water
Plants drown
Silt
1/16mm
Sand
2mm
Coarse
Doesn’t hold water
Dry
Gravel
>2mm

19. Loam:
Best supports plant life

21. Process of Soil Formation
1. Bedrock Weathers
“Bedrock”
Original rock layer
2. C Horizon Forms
“Parent Material”
Crumbled rock rests on top of bedrock
3. A Horizon
“Top Soil”
Plants and hummus begin to add to bedrock
4. B Horizon
“Sub Soil”
Smaller particles sink down with water creating a layer of clay

22. Rate of Soil Formation Increased heat= increased formation
Increased moisture=increased formation
Weaker rock=increased formation
WHY?
FASTER EROSION

23. Soil Types