Intro Soils Lecture 1a

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Intro Soils Lecture 1a

  1. 1. Introduction to Soils Instructor: Kitty O’Neil
  2. 2. AGPS 1103 – Intro Soils• 3 credits, lecture & lab each week• Syllabus – Contact info – Textbook, lab manual – Course outline – Exams, quizzes, lab reports, grading, project – Policies• Extensive use of Blackboard
  3. 3. Lecture 1 - overview• Importance of soil – Soil functions• Definition of soil• Components of soil – Mineral, organic, air, water• Soil formation, weathering – Parent materials – Soil formation processes – Soil differs from parent material• Soils vary in space and in time
  4. 4. Why do we care about soil? ?
  5. 5. Why do we care about soil?• Soil resources were and are a central factor in shaping human history and development.• Survival of humans and animals is dependent on light, water, air and soil.• Good, productive soil is a basic human need. – Grow our food, clean our water, clean our air
  6. 6. Why do we care about soil?“All civilization is basically dependent uponnatural resources. All natural resources …aresoil or derivatives of soil. Farms, ranges,crops and livestock, forests, irrigation water,and even water power resolve themselvesinto questions of soil. Soil is therefore thebasic natural resource.” - Aldo Leopold, Erosion and Prosperity, 1921
  7. 7. Why do we care about soil?• “Man—despite his artistic pretensions, his sophistication, and his many accomplishments—owes his existence to a six-inch layer of topsoil and the fact that it rains.” - Author unknown
  8. 8. What does soil DO?OK, so soil is important.Why? What does soil actually DO? ?
  9. 9. What does soil DO?1. Soil serves as a natural medium for the growth of plants,2. regulates and purifies water,3. recycles organic wastes and nutrients,4. provides habitat for soil organisms, and5. serves as physical support for building and construction.= Soil functions
  10. 10. What is ‘soil?’?
  11. 11. What is ‘soil?’Soil = the unconsolidatedmineral and organicmaterial on the immediatesurface of the earth.
  12. 12. Soil = solids + pore space Composition of typical soil, by volumeFrom Univ. of Massachusetts Extension Vegetable Program, Soil Basics, part I
  13. 13. Mineral particles > 2.0mm = Gravel 0.05 – 2.0mm, don’t stick together, gritty 0.002 - 0.05mm, smooth when wet<0.002mm, sticky whenwet, hard clods when dry from Hillel, 1998, Environmental Soil Physics, Academic Press
  14. 14. Organic matter• Wide range of organic materials – Living organisms • Plants, roots • Insects, nematodes • Fungi, bacteria – Non-living OM, products of decomposition of living things • Continuously decomposed, new compounds synthesized by other microorganisms• Holds mineral particles together to form aggregates• Over time, OM is lost from soil as CO2
  15. 15. Pore space = air + water• Air space provides gas exchange to organisms and plant roots• Water is needed by plants and organisms• Soil water also contains dissolved mineral compounds & nutrients needed by plants and organisms
  16. 16. Where did soil come from? ?
  17. 17. Where did soil come from?Soil has been formed by 5 major factors:1.Parent material (original form)2.Climate (precipitation and temperatureeffects)3.Macro- and microorganisms4.Topography (elevation, slope, position)5.Time
  18. 18. Where did soil come from? Parent material Climate x Organisms Topography Time
  19. 19. Where did soil come from? Parent material Climate x Organisms Topography Time
  20. 20. Soil Formation or ‘weathering’from Brady & Weil, TheNature and Properties ofSoils, Prentice-Hall publ.
  21. 21. Soil Formation or ‘weathering’From T.H. Cooper, Soil 2125, U. Minnesota,http://www.soils.umn.edu/academics/classes/soil2125/index.html
  22. 22. Weathering varies with climate, organisms From T.B. Walther, Introduction to Geography, http://www.geography.hunter.cuny.edu/~tbw/ncc/
  23. 23. Weathering varies with topographyFrom Smith, et al, Soil, in AccessScience@McGraw-Hill, http://www.accessscience.com, DOI10.1036/1097-8542.631500; after Simonson et al., Understanding Iowa Soils, Brown, 1952
  24. 24. Soil originated from ‘parent material’As a result of weathering, soil differs from theparent material :a)physically,b)chemically,c)biologically, andd)structurally.…this is an ongoing process…
  25. 25. Soils vary widely Parent  Variable material Climatex Organisms Topography  Variable Time  Really Variable
  26. 26. Soils vary widely
  27. 27. Soils vary widely
  28. 28. Soils vary widely
  29. 29. Lecture 1 - overview• Importance of soil – 5 Soil functions• Definition of soil• 4 Components of soil – Mineral, organic, air, water• Soil formation, weathering – Parent materials – Soil formation processes – Soil differs from parent material• Soils vary in space and in time
  30. 30. Questions?
  31. 31. Questions?

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