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PST 2310 SOIL Technology Chapter 1: The Importance of Soil Chapter 2: Soil Origin and Development

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PST 2310 SOIL Technology Chapter 1: The Importance of Soil Chapter 2: Soil Origin and Development

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    1. PST 2310 SOIL Technology Chapter 1: The Importance of Soil Chapter 2: Soil Origin and Development

    2. The Importance of Soil Soil shapes human history Egyptians 4000 years ago, Nile river The dust bowl 1930s, due to soil misuse World population doubles every 40 years Soil is non-renewable in our life time

    5. Soil Is a Life-supporting Layer of Material Core, mantle, crust, atmosphere Crust, rock is 50 miles thick Atmosphere is 170 miles thick Soil is thin layer in between

    7. Oxygen Plant roots need oxygen to grow. Temperature: Our temperate climate ranges between 40 to 85 degrees. Water, cycles from one stage to next, one location to next. Carbon, converted by photosynthesis. Nutrients, cycle through the soil.

    9. Photosynthesis & Respiration Photosynthesis: 6CO2+12H2O light energy -->C6H12O6+6O2+6H2O Respiration: C6h12o6+6o2--->.6co2+6h2o+energy (691 cal/mol)

    11. SOIL: A 3-PHASE SYSTEM Solid phase (45%) Liquid phase (25%) Gas phase (25%) Organic matter (5%)

    12. SOIL PHASES

    13. Agricultural Uses of Soil Cropland Grazing land Forest Other, especially landscape usage

    15. Nonagricultural Uses of Soil Recreation Foundations Shrink-swell potential Load bearing capacity Waste disposal Building materials

    17. Land Use in the United States Rangeland 132 Million Acres

    18. Soil Origin and Development The soil body Pedon, a small body of soil 10 to 100 sq ft Poly pedon, a collection of pedons

    20. Pedons Pedon C

    21. Soil Formation Physical weathering Frost Wedging Chemical Weathering Solution Hydrolysis Oxidation Root wedging

    22. Soil Formation and Root Wedging

    23. Rocks and Minerals Igneous rock. From volcanic activity. Sedimentary rock, deposited by wind or water. Sandstone Limestone Metamorphic rock. Sedimentary rock changed by pressure etc.

    25. Rocks and Minerals

    26. Rocks and minerals Picture page 20

    27. Rocks and Minerals Parent Material Glacial Ice Wind Water Gravity Organic deposits Climate Organisms Topography Time

    28. Parent Material Residual soils Formed in place Formed slowly

    29. Glacial Ice Carried materials of much of North America, 1,000,000 to 10,000 years ago Glacial drift,deposits left at melting Glacial till, dropped in place, no sorting Glacial outwash, sorted Lacustrine, lake deposits

    31. Wind Eolian deposits, soil deposited by wind Loess, wind deposited silt

    32. Eolian Wind Deposited Soil

    33. Water Alluvial soils deposited in moving fresh water Alluvial fans, form just below hills Levees, soil deposited in low ridges along a river bank Floodplains, large flat areas, soil settles out River terrace, when a river cuts a new path and leaves old area high and dry

    34. Alluvial Fan

    35. Water Marine sediments, form in the ocean Deltas, where a river meets the ocean and leaves deposits at the mouth

    36. Delta River Soil Deposits

    37. Gravity Colluvium, parent materials slid down a slope Talus, sand and rocks that collect at the foot of a slope

    38. A Talus Slide

    39. Organic Deposits Minerals soils contain less than 20% organic material Organic soils contain 20% or more organic materials, usually form under water Low oxygen under water retards decay

    40. Mineral Soils

    41. Climate Temperature affects speed of chemical reactions Reactions occur mostly above 60 degrees F Rainfall leaches materials deeper into the soil

    42. Effects of Climate Cooler temp More o.m.

    43. Effects of Climate

    44. Topography Steepness of slope effects water movement. Steep or south slopes are drier than gentle or north slopes. The top of a slope is drier than the bottom. Steep slopes promote erosion. Low spots gather soil and have higher O.M.

    46. Time Soil formation can be in as little as a hundred years with good conditions Under poor conditions, soil formation will take hundreds of years

    48. The Soil Profile The master soil horizons are; A,B,&C In order from the top down the horizons are O,A,E,B,C, and R

    50. The O horizon The O horizon is formed from wholly or partially decayed organic matter Usually occurs in undisturbed soil

    52. The A horizon Called topsoil by most growers Surface mineral layer where organic matter accumulates Looses clay, iron to leaching Best environment for growing crops

    54. The E horizon Zone of greatest eluviation Clay, chemicals are leached to lower level Light in color Usually found in sandy forest soils in high rainfall areas

    56. The B horizon Subsoil Zone of accumulation, or illuviation Collects materials leached out of the A horizon Lower O.M. A,E,& B are called solum

    58. Subdivisions of Master Horizons As soils age, they develop more layers than basic horizons Assume letter of both I.e.AB May also be identified by lower case letter that tells specific trait Further subdivision using number after lower case letter, I.e. Bt1 meaning two distinct layers in the B horizon

    60. Oa

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