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Section ii and iii

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Transcript

  • 1. Section II The Nature Of Soil
  • 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 III
    • Soil Erosion
  • 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