Section II The Nature Of Soil
Formation of soil <ul><li>can take thousands of years </li></ul>
Soil <ul><li>is a mixture of weathered rock, decayed organic matter, mineral fragments, water, and air </li></ul>
<ul><li>formation is influenced by climate, slope, type of rock, types of vegetation, and length of time that the rock has...
Composition of soil <ul><li>the ingredients that make up soil </li></ul>
<ul><li>1.  clay, silt, and sand are small particles of sediment </li></ul><ul><li>2.  decaying, dark-colored plant and an...
Soil profile <ul><li>made up of different layers of soil </li></ul>
Horizon O <ul><li>top layer of vegetation and organic matter </li></ul>
1.  Horizon A – top layer of soil <ul><li>May be covered with organic litter that may turn into humus </li></ul><ul><li>Fe...
2.  Horizon B – middle soil layer <ul><li>contains less humus and is lighter in color than A horizon </li></ul>
<ul><li>minerals travel from horizon A to B horizon in a process called leaching </li></ul>
Horizon C – bottom soil layer <ul><li>has very little organic matter and is not strongly affected by leaching </li></ul>
<ul><li>Contains rock – the parent material from the soil </li></ul><ul><li>Glaciers can deposit soil that did not form fr...
Soil types – differ in different places
Different regions have different climates that affect soil development
Parent rock affects soil formation and type of vegetation that grows in a region
<ul><li>Time affects soil development because the longer the weathering has occurred, the less the soil resembles parent r...
<ul><li>Soil on steep slopes develops poorly </li></ul>
Section III <ul><li>Soil Erosion </li></ul>
<ul><li>Soil erosion or loss is important because plants do not grow as well when topsoil is lost. </li></ul>
<ul><li>Causes and effects of soil erosion – many human activities disturb the natural balance between soil production and...
Agricultural Cultivation <ul><li>increased farming removes the plant cover, leaving soils open to wind and water erosion. ...
Forest Harvesting <ul><li>Removes forest vegetation which increases erosion and particularly damages tropical rain forest ...
1984 2004
Overgrazing <ul><li>Results when animals graze until almost all ground cover disappears </li></ul>
Excess Sediment <ul><li>Can damage the environment when soil erosion is severe </li></ul>
Preventing Soil Erosion <ul><li>Soil must be protected / conserved </li></ul>
Manage Crops <ul><li>Farmers plant shelter belts of trees to break the force of the wind </li></ul>
<ul><li>Bare soil can be covered with decaying plants to hold soil in place </li></ul>
<ul><li>Farmers can graze animals on vegetation instead of plowing it under </li></ul>
<ul><li>With no-till farming, plant stalks are left in the field to provide cover for soil </li></ul>
Reduce Erosion On Slopes <ul><li>Contour farming  reduces soil erosion by planting along the contours of slopes </li></ul>
<ul><li>Terracing creates steep-sided flat areas for crops on the sides of hills and mountains </li></ul>
Reduce erosion of exposed soil <ul><li>water sprayed onto bare soil to reduce wind erosion </li></ul>
<ul><li>Topsoil is replaced and trees are planted </li></ul>
<ul><li>Water flow can be controlled in strip mines </li></ul>
<ul><li>After mining, the land can be reclaimed </li></ul>
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Section ii and iii

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Section ii and iii

  1. 1. Section II The Nature Of Soil
  2. 2. Formation of soil <ul><li>can take thousands of years </li></ul>
  3. 3. Soil <ul><li>is a mixture of weathered rock, decayed organic matter, mineral fragments, water, and air </li></ul>
  4. 4. <ul><li>formation is influenced by climate, slope, type of rock, types of vegetation, and length of time that the rock has been weathering </li></ul>
  5. 5. Composition of soil <ul><li>the ingredients that make up soil </li></ul>
  6. 6. <ul><li>1. clay, silt, and sand are small particles of sediment </li></ul><ul><li>2. decaying, dark-colored plant and animal material is called humus </li></ul><ul><li>3. small spaces between soil particles may be filled with air or water </li></ul>
  7. 7. Soil profile <ul><li>made up of different layers of soil </li></ul>
  8. 8. Horizon O <ul><li>top layer of vegetation and organic matter </li></ul>
  9. 9. 1. Horizon A – top layer of soil <ul><li>May be covered with organic litter that may turn into humus </li></ul><ul><li>Fertile layer with more humus and less rock and mineral particles than other soil horizons </li></ul>
  10. 10. 2. Horizon B – middle soil layer <ul><li>contains less humus and is lighter in color than A horizon </li></ul>
  11. 11. <ul><li>minerals travel from horizon A to B horizon in a process called leaching </li></ul>
  12. 12. Horizon C – bottom soil layer <ul><li>has very little organic matter and is not strongly affected by leaching </li></ul>
  13. 13. <ul><li>Contains rock – the parent material from the soil </li></ul><ul><li>Glaciers can deposit soil that did not form from the bedrock beneath it </li></ul>
  14. 14. Soil types – differ in different places
  15. 15. Different regions have different climates that affect soil development
  16. 16. Parent rock affects soil formation and type of vegetation that grows in a region
  17. 17. <ul><li>Time affects soil development because the longer the weathering has occurred, the less the soil resembles parent rock </li></ul>
  18. 18. <ul><li>Soil on steep slopes develops poorly </li></ul>
  19. 19. Section III <ul><li>Soil Erosion </li></ul>
  20. 20. <ul><li>Soil erosion or loss is important because plants do not grow as well when topsoil is lost. </li></ul>
  21. 21. <ul><li>Causes and effects of soil erosion – many human activities disturb the natural balance between soil production and soil erosion. </li></ul>
  22. 22. Agricultural Cultivation <ul><li>increased farming removes the plant cover, leaving soils open to wind and water erosion. </li></ul>
  23. 23. Forest Harvesting <ul><li>Removes forest vegetation which increases erosion and particularly damages tropical rain forest soil </li></ul>
  24. 24. 1984 2004
  25. 25. Overgrazing <ul><li>Results when animals graze until almost all ground cover disappears </li></ul>
  26. 26. Excess Sediment <ul><li>Can damage the environment when soil erosion is severe </li></ul>
  27. 27. Preventing Soil Erosion <ul><li>Soil must be protected / conserved </li></ul>
  28. 28. Manage Crops <ul><li>Farmers plant shelter belts of trees to break the force of the wind </li></ul>
  29. 29. <ul><li>Bare soil can be covered with decaying plants to hold soil in place </li></ul>
  30. 30. <ul><li>Farmers can graze animals on vegetation instead of plowing it under </li></ul>
  31. 31. <ul><li>With no-till farming, plant stalks are left in the field to provide cover for soil </li></ul>
  32. 32. Reduce Erosion On Slopes <ul><li>Contour farming reduces soil erosion by planting along the contours of slopes </li></ul>
  33. 33. <ul><li>Terracing creates steep-sided flat areas for crops on the sides of hills and mountains </li></ul>
  34. 34. Reduce erosion of exposed soil <ul><li>water sprayed onto bare soil to reduce wind erosion </li></ul>
  35. 35. <ul><li>Topsoil is replaced and trees are planted </li></ul>
  36. 36. <ul><li>Water flow can be controlled in strip mines </li></ul>
  37. 37. <ul><li>After mining, the land can be reclaimed </li></ul>
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