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SOIL - Fundamental Concepts ABIOTIC

SOIL - Fundamental Concepts ABIOTIC. Prepared by Earl D. Lockridge National Soil Survey Center Lincoln, NE. Amended by: Mr. R. SOIL (Know this one).

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SOIL - Fundamental Concepts ABIOTIC

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  1. SOIL - Fundamental ConceptsABIOTIC Prepared by Earl D. Lockridge National Soil Survey Center Lincoln, NE Amended by: Mr. R

  2. SOIL (Know this one) • A mixture of mineral matter, organic matter, water, and air that originated from weathered bedrock and has become differentiated with depth into horizons Composite definition added Geomorphology book

  3. SOIL • Mature soil- clearly defined horizons produced by the weathering process. Each layer encroaches on the layer below it • Paleosols - ancient soils removed from the zone of soil formation, usually by burial from younger sediments.

  4. Major Components • Mineral matter • Organic matter • Air • Water

  5. SOIL • Component definition: Mixture of mineral matter, organic matter, water, and air. • Example: Air25% Mineral Matter 45% Water 25% Organic Matter5%

  6. CLIMATEandTIME –are the most important factors in soil formation • bedrock- The igneous, metamorphic, and sedimentary components of the Lithosphere that may exist as mountains, cliffs, or low lying plains

  7. Types of Bed Rock • Igneous- rock from volcanic sources or locations…can be very old • Examples- Granite & Quartz

  8. Types of Bed Rock • Sedimentary- rock formed by long term deposition by wind and water. Frequently found in layers. • Examples- Sandstone & Shale

  9. Types of Bed Rock • Metamorphic- rock which has been altered by high heat or pressure • Examples- slate (altered shale), gneiss (altered granite), diamond (carbon, coal)

  10. parent rock- anarea of bed rock that is the source of an area of soil

  11. How do we get soils?

  12. Over time the weathered material from the bed rock is covered by both living and dead organic material and a soil horizon develops in a dynamic way. • These layer become characteristically differentiated over time due to climatic factors in their environment

  13. Weathering • Disintegration and decomposition of rocks by surface processes. Geomorphology book

  14. Weathering • Mechanical- the physical process of breaking apart rocks (frost/salt wedging, root growth) • Chemical- breakdown through chemical alteration (oxidation, hydrolysis, acid inorganic or organic derived from Lichen, fungi, bacteria, mosses and all vascular plant roots) piru.alexandria.ucsb.edu/ ~tierney/TRS/lab6.htm –part of chemical definitdefinition taken form here

  15. Factors that Affect Soil Structure • Kind of clay • Amount of organic matter • Freezing and thawing • Wetting and drying • Action of burrowing organisms • Growth of root systems of plants

  16. Important Note • All of these have a loosening effect on the soil, but they have no effect on aggregate stability

  17. Soil Forming Processes • Translocations • Transformations • Additions • Losses

  18. Only one millimeter of topsoil is created on 2.5 acres every year (The Way the World Works, 1996 )

  19. Differentiated layer of developed soils are known as HORIZONS

  20. The Horizons • O- organic layer of decomposing plant material little mineral content • A- Organic acid design decomposing the parent material giving it a dark color. This is the zone of leaching. Dissolved chemical carried down from the surface. Accessible by plant roots. Most soil organisms found here O A http://cr.middlebury.edu/biology/treeline/educ_dialogue/virtual_tour/orig_images/how/collectingSS/LongMonowRulerwarrows.jpg

  21. The Horizons • B- Zone of accumulation. More weathering then C. Parent material is hard to identify. Can be full of clay (more so then the above layers) and impermeable (red brown color common because of oxidation). Nutrients collect in this region-mineral leach up form the parent rock below B C web.unbc.ca/~quarles/ nres/soc/ggroup/hp.html

  22. The Horizons • C- Slightly weathered parent material (bed rock). Has not undergone leaching and accumulation to the same extent of above layers less oxidation then the B layer • D or R- Bed Rock Bed Rock (Exposed) http://news.minnesota.publicradio.org/features/2005/05/09_steilm_rockmining/ml

  23. O A B C nesoil.com/images/ massasoit.htm

  24. Hint!! • Not all layers of soil may be present, but if they are they will always be in the following order O-A-(E)-B-C-R (or D)

  25. Three Fractions of Mineral Matter • Sand 2-.5mm (diameter) • Silt .49-.002mm • Clay smaller than .002mm

  26. USDA Textural Triangle

  27. Examples of Soil Structure

  28. Soil Color • Indicator of different soil types • Indicator of certain physical and chemical characteristics • Due to humus content and chemical nature of the iron compounds present in the soil

  29. loams – most fertile soil (silt, sand and clay in equal parts with partials of intermediate size)

  30. Why is loamy soil best?

  31. http://www.priweb.org/ed/pgws/systems/images/porosity.jpg Porosity • Porosity- the measure of how much water a rock can hold • finer (silt, clay) the grain greater overall surface area so more porosity, more poorly connected however

  32. http://www.earthnet-geonet.ca/glossary/display_term_e.php?term=permeability&showLetters=truehttp://www.earthnet-geonet.ca/glossary/display_term_e.php?term=permeability&showLetters=true Permeability • permeability- how easily the water can be transmitted • larger pores allow water to pass through easily (sand size and larger)

  33. There are 20,000 different types of soil in the United States! (The Way the World Works, 1996 )

  34. Local Soil Types

  35. PedogenicPedogenic means pertaining to processes that add, transfer, transform, or remove soil constituents. http://earthquake.usgs.gov/image_glossary/pedogenic.html

  36. Physical Properties of Soil • Soil texture • Soil structure • Soil color • Bulk density

  37. Aspects of Soil Structure • The arrangement into aggregates of desirable shape and size • The stability of the aggregate • The configuration of the pores

  38. Factors that Affect Aggregate Stability • Kind of clay • Chemical elements associated with the clay • Nature of the products of decomposition or organic matter • Nature of the microbial population

  39. Factors that Affect Soil Structure • Kind of clay • Amount of organic matter • Freezing and thawing • Wetting and drying • Action of burrowing organisms • Growth of root systems of plants

  40. Important Note • All of these have a loosening effect on the soil, but they have no effect on aggregate stability

  41. Major Forms of Iron and Effect on Soil Color FormChemical FormulaColor Ferrous oxide FeO Gray Ferric oxide (Hematite) Fe2O3 Red Hydrated ferric oxide (Limonite) 2Fe2O33H2O Yellow

  42. Bulk Density • Determined by dividing the weight of oven-dry soil in grams by its volume in cubic centimeters • The variation in bulk density is due largely to the difference in total pore space

  43. Effects of Bulk Density • Engineering properties • Water movement • Rooting depth of plants

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