1. The Nature Of Soil Ms. Scerra
Section I
The Nature Of Soil
Ms. Scerra

2. Formation of soil
can take thousands of years

3. Soil
is a mixture of weathered rock, decayed organic matter, mineral fragments, water, and air

4. Formation is influenced by climate, slope, type of rock, types of vegetation, and length of time that the rock has been weathering

5. Composition of soil
The ingredients that make up soil

6. 1. Clay, silt, and sand are small particles of sediment
2. Decaying, dark-colored plant and animal material is called humus
3. Small spaces between soil particles may be filled with air or water

7. Soil profile
Made up of different layers of soil

8. Horizon O
Top layer of vegetation and organic matter

9. 1. Horizon A – Top layer of soil
May be covered with organic litter that may turn into humus
Fertile layer with more humus and less rock and mineral particles than other soil horizons

10. 2. Horizon B – middle soil layer
Contains less humus and is lighter in color than A horizon

11. Minerals travel from horizon A to B horizon in a process called leaching

12. Horizon C – bottom soil layer
Has very little organic matter and is not strongly affected by leaching

13. Contains rock – the parent material from the soil
Glaciers can deposit soil that did not form from the bedrock beneath it

14. Soil types differ in different places

15. Different regions have different climates that affect soil development

16. Parent rock affects soil formation and type of vegetation that grows in a region

17. Time affects soil development because the longer the weathering has occurred, the less the soil resembles parent rock

18. Soil on steep slopes develops poorly

19. Section II : Soil Erosion
By: Ms. Scerra

20. Soil erosion or loss is important because plants do not grow as well when topsoil is lost.

21. Causes and Effects of Soil Erosion:
Many human activities disturb the natural balance between soil production and soil erosion.

22. Agricultural Cultivation
Increased farming removes the plant cover, leaving soils open to wind and water erosion.

23. Forest Harvesting
Removes forest vegetation which increases erosion and particularly damages tropical rain forest soil

24. 1984
2004

25. Overgrazing
Results when animals graze until almost all ground cover disappears

26. Excess Sediment
Can damage the environment when soil erosion is severe

27. Preventing Soil Erosion
Soil must be protected / conserved

28. Manage Crops
Farmers plant shelter belts of trees to break the force of the wind

29. Bare soil can be covered with decaying plants to hold soil in place

30. Farmers can graze animals on vegetation instead of plowing it under

31. With no-till farming, plant stalks are left in the field to provide cover for soil

32. Reduce Erosion On Slopes
Contour farming reduces soil erosion by planting along the contours of slopes

33. Terracing creates steep-sided flat areas for crops on the sides of hills and mountains

34. Reduce erosion of exposed soil
Water sprayed onto bare soil to reduce wind erosion

35. Topsoil is replaced and trees are planted

36. Water flow can be controlled in strip mines

37. After mining, the land can be reclaimed