1 / 66

SOIL FORMATION

SOIL FORMATION. Soil forms when weathered parent material interacts with environment. weathering. Wearing parent material down PHYSICALLY CHEMICALLY. Physical (Mechanical): disintegration of parent material into smaller pieces increases surface area:

dmatthew
Download Presentation

SOIL FORMATION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SOIL FORMATION Soil forms when weathered parent material interacts with environment.

  2. weathering • Wearing parent material down • PHYSICALLY • CHEMICALLY

  3. Physical (Mechanical): disintegration of parent material into smaller pieces increases surface area: surface area increases by about the same factor as particle size decreases.

  4. Chemical (Biogeochemical) acts on surfaces: primary minerals are broken down and secondary minerals are formed.

  5. Soil forms when weathered parent material interacts with the environment. What would constitute the ENVIRONMENT of a soil?

  6. Soil carbonic acid (formed from LIFE in soil) extracts minerals from soil(which came from parent material)

  7. How fast does soil form? Slow--------------------------------------Fast ~ 1 cm/1000 yr ~ 30cm/50yr Not very.

  8. Hans Jenny • 1941: soil is open system, properties are functionally related; system changes when property(ies) change(s). • Jenny’s CLORPT equation s = ƒ (cl, o, r, p, t) He expanded on the ideas of Dokuchaev

  9. 1. CLIMATE 2. ORGANISMS 3. RELIEF 4. PARENT MATERIAL 5. TIME

  10. 1. CLIMATE …determines speed, character of soil development: determines the type and rate of weathering determines living organisms and plants found in an area

  11. components of climate : • 1. Temperature • -for every 10°C , biochemical rxn rates 2X • 2. Effective precipitation • (water that moves through entire soil column, including regolith) • -depth of water = depth of weathering • -water moves soluble & suspended materials

  12. (Fig. 2.15) High temperatu

  13. Temperature and humidity increase the depth of weathering. Humid, tropics High latitude Dry, SW US Humid, SE US

  14. Effective precipitation -a) seasonal distribution -b) temperature, evaporation -c) topography -d)permeability

  15. a) Seasonal distribution of precipitation: Location B 600 mm/yr Location A 600 mm/yr 100mm 50mm 6 rainy months only Every month

  16. b) Temperature and evaporation: Location A hot Location B cool High evapotranspiration Low evapotranspiration 600 mm 600 mm Lower effective ppt Higher effective ppt

  17. Topography: concave or bottom of slope (receiving) level slope

  18. Permeability:

  19. 2. Organismsplant and animal (Living plants and animals on and in soil) -sources of organic matter -nutrient recycling -vegetation prevents erosion -type of vegetation influences soil type -base pumping -

  20. Type of vegetation influences soil type

  21. Base pumping Deciduous trees are more effective base pumpers than conifers . -needles are hard to break down -basic cations leach away: soil is acidic -deciduous litter is easy to break down -cations (bases) are released so surface soils are not acidic

  22. Macroanimals (insects, mammals, gastropods, earthworms) • mix, bind soil; create channels for air, water

  23. crotovinas

  24. night crawlers and water

  25. Macroanimals (insects, mammals, gastropods, earthworms) • mix, bind soil; create channels for air, water • Microanimals (nematodes, protozoa)

  26. Macroanimals (insects, mammals, gastropods, earthworms) • mix, bind soil; create channels for air, water • Microanimals (nematodes, protozoa) • Macroplants (the green plants) • provide organic matter, roots create channels, adsorb nutrients, release CO2, stabilize, protect from erosion

  27. Macroanimals (insects, mammals, gastropods, earthworms) • mix, bind soil; create channels for air, water • Microanimals (nematodes, protozoa) • Macroplants (the green plants) • provide organic matter, roots create channels, adsorb nutrients, release CO2, stabilize, protect from erosion • Micro “plants” (fungi, bacteria, actinomycetes, algae) • decomposers

  28. 3. Relief/Topography • important for rate of runoff, erosion, drainage

  29. Flat valley floors and flat ridge tops: soil accumulates; (deepening>removal) Slopes: (removal> deepening)

  30. 4. Parent Material Determines: • texture, • types of weathering, • mineral make-up

  31. Some Physical Weathering Processes: 1. Freeze/thaw

  32. Freeze / Thaw

  33. Physical: 1. Freeze/thaw 2. Exfoliation

  34. 2. Exfoliation (unloading)

  35. Physical: 1. Freeze/thaw 2. Exfoliation 3. Abrasion

  36. 3. Abrasion (wind, water, ice) wind

  37. water

  38. ice

  39. Physical: 1. Freeze/thaw 2. Exfoliation 3. Abrasion 4. Salt wedging

More Related