1 / 53

Chapter 11 - Soil Resources

Chapter 11 - Soil Resources. i t’s just dirt!. I. Soils: Products of Weathering. Soil  loose surface materials composed of weathered rock and mineral materials with variable amounts of organic matter can support growth of plants resting upon bedrock. Soils.

akio
Download Presentation

Chapter 11 - Soil Resources

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. Chapter 11 - Soil Resources it’s just dirt!

  2. I. Soils: Products of Weathering • Soil  loose surface materials composed of weathered rock and mineral materials with variable amounts of organic matter • can support growth of plants • resting upon bedrock

  3. Soils B. Residual vs. Transported Soils • Residual formed “in situ” via weathering • Transported  formed elsewhere & deposited alluvial, glacial, wind deposited Example  loess soils & the Palouse

  4. Soils C. Soil Profile  vertical section of soil from surface to bedrock D. Soil Horizons  layers of soil (in profile) distinguished by color, texture, structure & composition

  5. Soil Profile & Horizons

  6. Soils E. Color & Texture 1. Color indications of composition • Higher organics  darker color • Higher iron  redder color • Higher calcium or salts  whitish colors

  7. Soils 2. Texture • Grain sizes  Sand, silt, clay • often determines physical properties -looseness/compactibility -drainage & moisture retention

  8. Soil Texture

  9. Soils F. Soil Classification  “a pain in the _____!” • Early attempts  Zonal classificationbased on climate controls, temp. vs. rainfall

  10. Classification • “modern” classification  soil science vs. engineering classification • Classified by physical characteristics • 14,000 soil “series” now recognized! • Forgetaboutit!

  11. II. Soil Resources & Problems Soil a renewable resource? • Soil Erosion • U.S. farmlands, 1992 = 2 billion tons • ~4.8 tons/acre, average annual loss • ~1.6 tons/acre, avg. annual formed • accumulated side effects!

  12. Soil Erosion Styles of erosion • Sheet • Rill • Gullying • Wind

  13. Global Soil Erosion

  14. II. Soil Resources & Erosion B. Causes • Natural • Human-related • Overgrazing & bad agriculture techniques • Deforestation • Recreational activities

  15. Case Study: Palouse soil erosion • Palouse region, eastern WA  Go COUGS! • Loess soil  wind blown silt

  16. Case Study: Palouse soil erosion • Formed during Pleistocene glaciation • Several hundred feet thick in places • High fertility, important physical properties & agricultural potential • Interesting historical ramifications

  17. Palouse soil & erosion issues

  18. Palouse soil erosion • Up to 25 tons/acre/year erosion • Highest rates  200 tons/acre/year!  steeper slopes • ~.17 inches/year  8.5 inches/50 years *Farm near Thornton, WA  4.5 feet of soil lost in less than 50 years!

  19. Palouse soil erosion • 20% + of cropland eroded to subsoils • Decreased yields • Increased fertilizers needed, decreased soil pH (acidifying) Dirt: The Erosion of Civilizations, 2007, David Montgomery, University of California Press

  20. Palouse soil erosion Contributing factors to Palouse erosion? • Intensive mechanized farming  tractor plowing began (1930’s) • Plowing on hillsides • Rain on freshly plowed land  rilling/gullying • Wind storms  age-dated lake cores  4-fold increase in erosion w/modern plowing

  21. II. Soil Resources B. Soil Contamination • Industrial pollution • Salinization

  22. II. Soil Resources & Problems C. Expansive Soils • expansion upon water saturation • shrink when dried out • $6 billion/year damages • Clay-rich soils Why is clay the culprit?

  23. Expansive Soils Mitigation • How to deal with expansive soils? • Hire a geoengineering firm & spend lots of $$$$ fixing the problem after, or….. • Spend less $$$$$ before • http://web.mst.edu/~rogersda/umrcourses/ge341/

  24. II. Soil Resources & Problems D. Settlement • Non-uniform settling and compaction  • Differential settlement • Soils with strength & cohesion differences READ  Leaning Tower of Pisa

  25. II. Soil Resources & Problems E. Permafrost • Permanently frozen ground • Northerly, polar latitudes • Freezing depth (winter) exceeds thaw depth (summer)

  26. Case Study: The Trans-Alaska Pipeline • Prudhoe Bay (North Slope) oil fields • Discovered 1968 – “world class field” • Remote location, cold water port • No oil tankers! How to get the oil to market? • 1300 km (~800 mi) pipeline

  27. Trans Alaskan Pipeline B. Pipeline Route • Prudhoe Bay to Valdez (Prince William Sound) • Inaccessible wilderness • 2 mountain ranges, large river crossings • LARGE areas of permafrost

  28. Trans Alaskan Pipeline C. Planning Studies, Designs, & Cost • Prefeasibility studies  mapping & drilling bedrock vs. permafrost • Identified faults  active Denali fault • Permafrost dilemma  oil needs to flow @ 65oC in 48” pipeline *1/2 of pipeline must be above ground  why?

  29. Trans Alaskan Pipeline Above ground design MUST: • Dissipate heat away from ground • Allow for fault movements & earthquakes • Vertical support members (down to 60’) w/heat exchangers & refrigerant • Horizontal beam & jiggle joints for magnitude 8 quake

  30. Building on permafrost

More Related