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    Soil

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    jojorob7

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    © All Rights Reserved
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    Soil

    Uploaded by

    jojorob7
    15 views18 pages

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    Soil PPT

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    Copyright:

    © All Rights Reserved
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    Download as ppt, pdf, or txt
    15 views18 pages

    Soil

    Uploaded by

    jojorob7

    Copyright:

    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    of 18

    5.

    2 Soil

    Characteristics of Soil
     Soil is part of the regolith that supports
    the growth of plants.
    • Regolith is the layer of rock and mineral
    fragments that covers most of Earth’s land
    surface.
    5.2 Soil

    Characteristics of Soil
     Soil Composition
    • Soil has four major components: mineral matter,
    or broken-down rock; humus, which is the
    decayed remains of organisms; water; and air.
    Composition by Volume of
    Good-Quality Soil
    5.2 Soil

    Characteristics of Soil
     Soil Texture
    • Texture refers to the proportions of different
    particle sizes.
    - Sand (large size)
    - Silt
    - Clay (small size)
    • Loam (a mixture of all three sizes) is best suited
    for plant life.
    5.2 Soil

    Characteristics of Soil
     Soil Texture (SAND)
    -Sand has less nutrients for plants than smaller
    particles

    -Voids between sand particles promote free


    drainage and entry of air

    -Holds little water and prone to drought


    5.2 Soil

    Characteristics of Soil
     Soil Texture (SILT)

    -Smaller particles – retains more water for plants


    and have slower drainage than sand.

    -Easily washed away by flowing water – highly


    erosive.

    -Holds more plant nutrients than sand.


    5.2 Soil

    Characteristics of Soil
     Soil Texture (CLAY)

    -Pores spaces are very small and convoluted


    Movement of water and air very slow

    -Water holding capacity


    Tremendous capacity to adsorb water-
    not all available for plants.

    -Chemical adsorption is large


    5.2 Soil

    Characteristics of Soil

    Soil Consistence
    -Loose: the soil breaks apart when held

    -Friable: the soil breaks apart with a


    small amount of force

    -Firm: the soil breaks apart with a lot of


    pressure between two fingers
    5.2 Soil

    Characteristics of Soil
     Soil Structure
    • Soil particles clump together to give a soil its
    structure.
    Humus/Organic Matter
    Humus/Organic Matter
    •Organic
    Organicmatter
    matterisismade
    madeup
    upof:
    of:
    – Decomposing Plants
    – Decomposing Plants
    Such as leaves and flowers
    Such as leaves and flowers
    AND
    AND
    -Decomposing animals
    – Decomposing animals Such as insects
    Such as insects
    • Organic Matter breaks down into nutrients
    • which
    Organic
    areMatter breaks
    used by plantsdown into nutrients
    for growth.
    which are used by plants for growth.
    5.2 Soil

    Soil Formation
     The most important factors in soil
    formation are parent material, time,
    climate, and organisms.
    1. Parent material
    • Residual soil—parent material is the bedrock
    • Transported soil—parent material has been
    carried from elsewhere and deposited
    5.2 Soil

    Soil Formation
    2. Time
    • Important in all geologic processes
    • The longer a soil has been forming, the thicker
    it becomes.
    3. Climate
    • Greatest effect on soil formation
    5.2 Soil

    Soil Formation
    4. Organisms
    • Organisms influence the soil's physical and
    chemical properties.
    • Furnish organic matter to soil
    5.2 Soil

    The Soil Profile


     Soil varies in composition, texture, structure,
    and color at different depths. Soil horizons
    are zones or layers of soil. A soil profile is a
    vertical section through all the soil horizons.

    • The A horizon is commonly know as topsoil.


    • The B horizon is subsoil and contains clay
    particles washed out from the A horizon.
    • The C horizon is between B horizon and
    unaltered parent material.
    Soil Profile
    A Soil Profile Showing
    Different Horizons
    5.2 Soil

    Soil Erosion
     Water erodes soil.
     Rates of Erosion
    • Human activities that remove natural vegetation,
    such as farming, logging, and construction, have
    greatly accelerated erosion.
    5.2 Soil

    Soil Erosion
     Controlling Erosion
    • Planting rows of trees called windbreaks
    • Terracing hillsides
    • Plowing along the contours of hills
    • Rotating crops

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