1. SOIL
What’s the dirt on dirt?

2. Why study soil in environmental science???
Soils are the foundation for ecosystems.
Understanding soils and the organisms that rely on it allows us to understand how human activity can affect those organisms
For example….
Waste, Construction, Mining, Deforestation all affect soils

3. Importance of Soil
“Essentially, all life depends upon the soil…there can be no life without soil and no soil without life; they have evolved together.”
Charles E. Kellogg, USDA Yearbook of Agriculture, 1938

4. What is IN soil???
Air
Water
Humus – dead organic matter (animal & plant remains/feces)
Organisms
Rocks
Minerals

5. How Rocks Become Sediments (soils)
Rocks can be broken down from their parent material and transported to far away new locations and deposited. The processes that accomplish this are called weathering, erosion and deposition.

6. Weathering: the break down of rock, minerals or soils through physical or chemical means.
Mechanical: the physical break down of rock through friction and movement
Ex: plants and animal burrowing, wind-deserts, running water, gravity (falling rocks), waves-beaches, frost wedging (water gets in cracks, expands when it freezes causing wedges to open rocks.

7. Gravity can also weather rocks. Earth pulls down on rocks
Gravity can also weather rocks. Earth pulls down on rocks. See all of the fallen broken rock pieces
at the base of Mount Rushmore.

8. Water rounds rocks as it moves

9. Wind – weathers rock

10. Cleopatra’s
Needle

11. Burrowing Animals expose rocks

13. Chemical: breaking down rock through chemicals and chemical reactions
Ex: rainfall, acid rain

15. Examples: wind, water (rivers, waves, waterfalls), gravity, glaciers
2. Erosion: movement of sediment and rock particles from one location to another.
Examples: wind, water (rivers, waves, waterfalls), gravity, glaciers

16. 3. Deposition: depositing materials in layers by dropping the sediments and particles in a new location. Wind or water lays down sediments
Examples: gravel, beaches, sand bars

17. The Deltas of rivers- slow water flow where the river meets the ocean causes sediments to sink
Aerial view of the Mississippi delta

18. So what do we do with the soil once it is formed???
Soil is used to support plant life – the base of the food chain and original food source for all other organisms
Plants need…
Sunlight (from the sun)
Water (retrieved from the soil)
Nutrients (retrieved from the soil)

19. Soil fertility This gives an indication of the quality of the soil.
A measure of the ability of soil to provide plants with
1) sufficient amount of nutrients (measured by nutrient holding capacity) and
2) water (determined by porosity, permeability and percolation), and
3) a sturdy place for plants to anchor their roots

20. Nutrient Holding Capacity
A soil’s ability to hold on to nutrients long enough for plants to absorb them
Nutrients include nitrogen and phosphorous

21. WATER
As discussed, water is also necessary for plants to grow. Soil plays a role in water availability to plants. Ability to provide water is determined by porosity, permeability and percolation.

22. In order to discuss this you must first understand the following:
1. Porosity:
the volume of water/air the soil (spaces between the rock particles) can hold. The more porous a rock is, the more water it can hold.
Water/pollution filled pore
Gas/Air filled pore

23. Soil porosity doesn’t describe how well water or other liquids move through soils. Permeability addresses this concept.
2. Permeability: the ability for water/air to flow through the rock
For example-gravel and sand are very permeable. Clay and granite are impermeable.

24. Percolation (infiltration): water trickling into the ground; a liquid (water) passing gradually through small spaces or a porous substance (soil).

25. Soil depletion
Nutrient-rich soil being removed from an area and not replaced so plants are not able to grow as well or not at all. It can be caused by over-farming, deforestation, etc.
Deforestation and overgrazing are causing soil depletion, erosion and desertification throughout Western Asia and many other parts of the world.

26. SANDY SOIL Porosity – Low – it can hold air but not water
Permeability - High
Nutrient Holding Capacity - Low

27. CLAY SOIL Porosity – Low – it can hold air but not water
Permeability - High
Nutrient Holding Capacity - Low

28. LOAM SOIL Porosity – Medium Permeability - Medium
Nutrient Holding Capacity - High

30. With soil made from weathering rock, LAND that is now made can be used.
With optimal water and nutrient holding capacity, plants can be grown for food, clothing, oxygen and more.