1. The Ground Beneath Our Feet
SOIL UNIT

2. What Makes Up Healthy Soil?
Mineral fragments, humus, air, water, and living things
Plant roots, Insects, Worms
Humus
Organic Material
Can support the growth of vegetation
Parent rock
source of mineral fragments in the soil

3. Soil Formation Soil starts out as rock
The surface rocks break down into smaller pieces and is mixed with organic matter.
Over time this creates a thin layer of soil.
Decaying matter makes the soil thick and rich

5. Soil Texture
The soil’s quality is based on the proportions of soil particles.
Soil texture affects
Consistency:
soil’s ability to be broken up.
Infiltration:
ability of water to move through soil.

6. Sizes of Weathered Rock That Make Up Soil

7. Different Types of Soil
Every soil type is a mixture of sand, silt, clay.
The right mixture is called loam.
Loam =
40% sand
40 % silt
20 % clay

8. Soil Profile The vertical display of soil horizons.
Each soil profile is different from another

9. SOIL HORIZON INTRO
O horizon: made from the litter from dead plants and animals. Leaves, pine straw covering the ground. Decayed plant matter enriches the topsoil with nutrients. O stands for organic.
C horizon: Partially weathered bedrock. Made of large rocks and bedrock just starting to weather. Usually no roots here. Regolith starts here.
A horizon: Topsoil. Usually dark in color. Rich in humus. Most developed of all the layers. Most fertile layer of soil. Plants root here.
E horizon: Water leaches many of the nutrients from this layer after a rain. The nutrients end up in the subsoil. Poor in nutrients
R horizon: Bedrock. Parent material of the residual soil above. Large, continuous masses of rock. Difficult to dig through!
B horizon: Subsoil. Fine particles of clay and nutrients seep down here. Tree roots can reach this far.

10. What is a Soil horizon? O Litter from dead plants and animals A
Topsoil E
Zone of intense leaching. B
Collects dissolved substances from upper horizons C
Weathered bedrock R
Bedrock

11. SOIL CONSERVATION TECHNIQUES(ON BACK)
TERRACING… PREVENTS EROSION FROM HEAVY RAINS ON STEEP HILLS..
****SMALLER, FLATTER FIELDS

12. SOIL CONSRERVATION TECHNIQUES(ON BACK)
CONTOUR PLOWING… HELPS PREVENT EROSION FROM HEAVY RAINS..**PLOW ACROSS THE SLOPE OF HILL, ROWS ACT AS DAMS NOT RIVERS

13. SOIL CONSERVATION TECHNIQUES(ON BACK)
COVER CROPS….RESTORES NUTRIENTS TO SOIL…***PROTECT SOIL FROM WIND AND RAIN, PREVENT EROSION…

14. SOIL CONSERVATION TECHNIQUES(ON BACK)
NO-TILL FARMING…PREVENTS EROSION BY PROVIDING COVER THAT REDUCES WATER RUNOFF..***LEAVE OLD STALKS, DON’T CUT DOWN*****

15. WIND BREAKS

16. CROP ROTATION-PLANT DIFFERENT CROPS EACH YEAR

17. Review Questions Which particle is the biggest one that goes in soil?
A. Clay
B. Silt
C. Quartz
D. Sand

18. Review Questions Which particle is the biggest one that goes in soil?
A. Clay
B. Silt
C. Quartz
D. Sand

19. Review Questions How does soil texture affect soil consistency?
A. It has nothing to do with it.
B. Allows water to pass through it easier.
C. The soil’s ability to allow farmers to manipulate it.
D. Allows for plants to grow easily.

20. Review Questions How does soil texture affect soil consistency?
A. It has nothing to do with it.
B. Allows water to pass through it easier.
C. The soil’s ability to allow farmers to manipulate it.
D. Allows for plants to grow easily.

21. Review Questions What is loam?
A. Loam is the perfect combination of sand, silt, and clay.
B. Loam is the combination of 30% sand, 40% mud, and 30% clay.
C. Loam is located on in horizon B.
D. Loam is the particle quality of any soil.

22. Review Questions What is loam?
A. Loam is the perfect combination of sand, silt, and clay.
B. Loam is the combination of 30% sand, 40% mud, and 30% clay.
C. Loam is located on in horizon B.
D. Loam is the particle quality of any soil.

23. Soil pH Have you ever seen this? Why does this happen?
What creates CO2?

24. Soil pH
Carbonic acid and Humic acid changed the pH of the soil to be more acidic.
Carbonic acid
come from Carbon Dioxide.
Humic acid
various organic acids produced from humus.

25. Tropical Climate Very rich humus. Very little topsoil
Leeching of nutrients from topsoil to horizon B and C.
Plants demand a lot of nutrients.

26. Desert Climate Deserts get less than 25 cm rain a year.
Slow rate of weathering = Slow rate of soil formation.
Due to no water, salt gathers in the ground.
Salt is toxic to plants!

27. Temperate Climate Lots of weathering = lots of fertile soil
Most productive soil in the world.
Most of Continental USA has a temperate climate.

28. Arctic Climate Very cold desert = Slow rate of soil formation.
Low amount of humus due to cold temperatures.
Cold temperatures
slow down
decomposition.

29. Review Questions What acids can change the pH of the soil?
A. Humic acid and Hydrochloric acid
B. Carbonic acid and Humic acid
C. Carbonic acid and water
D. Water and citric acid

30. Review Questions What acids can change the pH of the soil?
A. Humic acid and Hydrochloric acid
B. Carbonic acid and Humic acid
C. Carbonic acid and water
D. Water and citric acid

31. Review Questions
Which climate is called the “breadbasket of the world”?
A. Tropical
B. Desert
C. Temperate
D. Arctic

32. Review Questions
Which climate is called the “breadbasket of the world”?
A. Tropical
B. Desert
C. Temperate
D. Arctic

33. Review Questions Which climate has very little, but fertile topsoil?
A. Tropical
B. Desert
C. Temperate
D. Arctic

34. Review Questions Which climate has very little, but fertile topsoil?
A. Tropical
B. Desert
C. Temperate
D. Arctic