1. Soil

2. Soil – a loose mixture of small mineral fragments and organic material
Bedrock to Soil
Soil – a loose mixture of small mineral fragments and organic material
Bedrock – layer of rock beneath the soil;
this layer has never been weathered

3. Sources of Soil
Parent rock is the rock that is the source of the soil.
The soil made from granite ( ) will look differently than the soil made from limestone ( )
Parent Rock
Parent Rock

4. Sources of Soil
Residual soil- soil that remains above the bedrock from which it is formed
Transported soil – soil that is blown or washed away( ) from its parent rock
Erosion

5. Sources of Soil
Humus – very small particles of decayed plants and animal material; also known as the organic part of the soil

6. Soil Layers
Soil layers are also known as horizons.

7. Horizon ‘0’
Contains fresh or decaying organic material (leaves, plants, animals) known as
Forest soil =
Desert soil =
Humus.
Thick
Thin

8. Soil Layers
Leaching – Rainwater from the surface travels down through the horizons; it dissolves minerals and nutrients, and other substances from the soil above.

9. Soil and Climate TROPICAL CLIMATES
CLIMATE - Air is humid and the land receives a lot of water
Leaching occurs quickly and constantly, producing a thin topsoil layer.
                                               
              

10. Soil and Climate DESERT CLIMATES
CLIMATE - Very dry and very little rain
Water evaporates quickly, causing the soil to have large concentrations of salts, which can produce toxic soil (even to desert plants)
EX: Death Valley
                                               

11. Soil and Climate TEMPERATE CLIMATES
CLIMATE - Enough rain and varying temperatures
Thick and fertile soil develops due to the abundance of chemical and mechanical weathering.
EX: United States
                                               
                                               

12. Soil and climate ARCTIC CLIMATES
CLIMATE - Little precipitation and extremely cold temperatures
Soil formation occurs slowly due to cold temperatures; the topsoil is extremely thin and unable to support most plants.
                                               
              

13. What do you remember?
The source of mineral fragments in soil is called the ______________.
The organic part of soil is called ___________.
The soil horizon that contains only humus is called _______________.
Soil that remains above the bedrock from which it is formed is called _____________.

14. What do you remember? (cont.)
Describe the topsoil in the desert climates and in temperate climate.
What climate in the United States is called the “breadbasket” for the many crops the region’s soil supports?
What do you find at the different horizons or what is another name?
Horizon A
Horizon B
Horizon C
Horizon R

15. Answers
The source of mineral fragments in soil is called the ______________.
Parent rocks
The organic part of soil is called ___________.
Humus
The soil horizon that contains only humus is called _______________.
Horizon O
Soil that remains above the bedrock from which it is formed is called _____________.
Residual Soil

16. Answers
Describe the topsoil in the desert climates and in temperate climate.
Desert – thin and salty
Temperate – thick and fertile
What climate in the United States is called the “breadbasket” for the many crops the region’s soil supports?
Temperate Climate

17. Answers What do you find at the different Horizons? Topsoil Subsoil
Horizon A
Horizon B
Horizon C
Horizon R
Topsoil
Subsoil
Partially weathered Rock
Bedrock

18. Soil and Soil Conservation

19. Soil Conservation
Consists of the various methods by which humans take care of soil

20. Review! Humus Soil takes a long time to grow!
Is the part of soil made up of decayed parts of once-living things
It is dark and soft
Soil takes a long time to grow!
It takes 500-1,000 years to grow 1 inch of soil
Deep soil takes thousands of years to form

21. Layers of Soil Topsoil Subsoil Bedrock The top layer
Made of the smallest grains
Richest layer of soil due to the having the most humus
Subsoil
Layer under topsoil
Larger grains
Less humus
Bedrock
Solid rock under soil
Weathering breaks down rock into soil
Made of different minerals

22. Importance of Soil
Soil contains the minerals that all living things need!

23. What Did We Learn? There are many types of soil
Soils are made from different minerals
Soils have different colors and different sized grains
Soils can hold different amounts of water
Soils that are best for plants have the right mixture of minerals and humus

24. Soil That is Good for Plants

25. Soil Facts
Soil is an important resource just like water, air, trees, and minerals.
If the same type of crop is grown in soil for many years on the same land it could harm the soil.
Plants use up the nutrients in the soil, then the soil is too poor for growing more crops.

26. Why is Soil so Important?
Minerals and nutrients for plants
Housing for many organisms (earthworms, spiders, moles, prairie dogs)
Storage- Soil stores water

27. Saving Soil
Resource: a material found in nature that living things use
Conservation: saving resources by using them carefully

28. How Can Soils Be Harmed? Examples of how soil can be harmed:
1. Cutting down trees
2. Over-farming
3. Erosion- wind and water transport soil and sediment

29. Ways to Save the Soil 1. Strip cropping 2. Contour plowing
3. Crop rotation
4. Cover crop

30. Ways to Save the Soil
1. Strip cropping: planting strips of thick grass or clover between strips of crops
2. Contour plowing: planting rows of crops around the sides of hills (across the slope of a hill) instead of up and down

31. Ways to Save the Soil
3. Crop rotation- In order to prevent nutrient depletion, crops planted in certain areas are changed year to year
4. Cover crop- a crop that is planted between harvests to reduce soil erosion and to replace certain nutrients in soil
Ex: Clover and soybeans

32. What Did We Learn?
Growing the same type of crop on the same land for many years removes minerals.
When people remove plants and trees, soil may be washed away.
Farmers conserve soil

33. The Dustbowl of the 1930s