Chapter 2 Formation of Soils from Parent Materials

1. Chapter 2 Formation of Soils from Parent Materials Sampling moon “soil.” (NASA, Apollo 14)

2. Figure 2.1 (a) (b)

3. Figure 2.2

4. Figure 2.3

7. Unloading Temperature Thermal Expansion Freeze-Thaw Frost Wedging Abrasion Water, Ice, Wind Biological Activity Burrows Root Wedging Physical Weathering Processes

8. Hydration Intact water molecules combine with a mineral5Fe2O3 + 9H2O Fe10O15(9H2O) Hydrolysis Water Molecule splits into hydrogen and a hydroxyl and the hydrogen replaces a cation from the mineral structure KAlSi3O8 + H2O HAlSi3O8 + K+ + OH- Dissolution Aided by small amounts of acid in the water Soluble ions are retained in the underground water supply CaCO3 + 2[H+(H2)O] Ca2+ + CO2 + 3H2O OR CaSO4(2H2O) + 2H2O Ca2+ + SO42- + 4H2O Biogeochemical Weathering Processes

9. Carbonation Weathering is accelerated by the presence of weak acids CO2 + H2O H2CO3 (Carbonic Acid) Then H2CO3 + CaCO3 Ca2+ + 2HCO3- Oxidation-Reduction Any chemical reaction in which a compound or radical loses electrons Important in decomposing ferromagnesian minerals 4Fe + 3O2 2Fe2O3 Or4Fe(2-)O + O2 + 2H2O 4Fe(3-)OOH (Goethite) Biogeochemical Weathering Processes

10. Figure 2.5 (a) (b)

11. Figure 2.6 (a) (b)

12. Development of Clays • The breakdown of parent rock results in the development of clays

13. Climate Primarily precipitation and temperature Organisms Especially vegetation, microbes, and soil animals Relief Slope, aspect, and landscape position Parent Material Geological or organic precursors to the soil Time Factors Influencing Soil FormationCLORPT

14. The parent material is what the soil and the nutrients ultimately come from Examples Colluvium Alluvium Floodplain Glacial Marine Sediments Loess Organic Bogs Effects of Parent Material

15. Figure 2.11

16. Figure 2.12 A productive soil in the Appalachian Mountains formed on colluvium

17. Figure 2.14 Alluvial fans merging into a Bajada in Alaska, which will form well-drained soils

18. Figure 2.13

19. Figure 2.15

20. Glacial Erosion

21. Glacial Erosion

22. Figure 2.17

23. Figure 2.16 1. Till deposits of various kinds2. Glacial-lacustrine deposits3. The Loessial blanket4. Area that escaped glaciation but has loess

24. Figure 2.18

25. Figure 2.19 GlacialTill GlacialOutwash

26. Figure 2.20 Distribution of Dune Sands and Loess Deposits

27. Homes carved from Loess deposits in China

28. Figure 2.22 Development of a peat bog resulting in Histosols

29. Effective Precipitation Depends on timing, topography, and soil type Temperature Effects the rate of weathering Climate also affects vegetation Effects of Climate

30. Box 2.1 a. Seasonal Distribution, b. Temperature and Evaporation, c. Topography, d Permeability

31. Figure 2.23 Temperature and Precipitation work together to affect depth of regolith weathered from bedrock

32. Climate and Vegetation are interconnected Figure 2.24

33. Flora Lichen, Moss, Trees Fauna Mites, Nematodes, Springtales, Earthworms Effects of Organisms

34. Figure 2.8 The effect of lichen etching bedrock

35. Figure 2.25 Difference in the soil profile under grassland versus forest vegetation

36. Change in soil Ph because of forest type

37. Semiarid rangeland vegetation will locally enhance fertility, photos from Patagonia Argentina

38. Figure 2.28 Prairie dog burrows help to mix the soil (called crotovinas), photo taken in Illinois

39. Slope and Aspect Determines amount of solar radiation absorbed Parent Material Interactions Affects the distribution of colluvium and alluvium Salt Buildup Arid areas slats are leached from relatively higher areas to lower areas Interaction With Vegetation Moisture regime is affected by microtopographic changes which in turn controls vegetation distributions Effects of Topography

40. Figure 2.29 Topographic influence on soil depth (a) (b)

41. Figure 2.30

42. All soil forming processes occur over a very long period of time The time it takes to develop a soil is relative, dependent upon Climate Vegetation Human Interaction Effects of Time

43. Figure 2.31

44. Catenas When soils are developed on the same parent material and the soils only differ on the basis of drainage due to variations in relief Chronosequence A sequence of related soils that differ in certain properties primarily as a result of time as a soil-forming process Lithosequence A group of related soils that differ as a result of parent material Climosequence A sequence of soils that differ as a result of changes in climatic regimes (temperature and precipitation) Biosequence A group of related soils that differ primarily due to variation in kinds and numbers of plants and soil organisms When Everything Else Is Held Equal (Sequences)

45. Transformation When soil constituents are chemically or physically modified or destroyed and others are synthesized from precursor materials Translocation The movement of organic and inorganic materials horizontally or vertically across a pedon Additions Inputs of materials from outside sources (i.e. plant litter) Losses Materials that are removed from the soil profile by leaching or erosion Four Basic Processes of Soil Formation

46. Figure 2.32