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  •  The way a soil “feels” is called the soil texture.  Soil texture depends on the amount of each size of particle in the soil.  Sand, silt, and clay are names that describe the size of individual particles in the soil. Sand  are the largest particles and they feel “ gritty .” Silt  are medium sized, and they feel soft, silky or “ floury .” Clay  are the smallest sized particles, and they feel “ sticky ” and they are hard to squeeze.
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Soil Soil Presentation Transcript

  • SOIL: Make it Work for You! We Study Soil Because It’s A(n) Great integrator: all parts of ecosystem Producer and absorber of gases Medium for plant growth Medium of crop production Home to organisms (plants, animals and others) Waste decomposer Snapshot of geologic, climatic, biological, and human history Source material for construction, medicine, art, etc. Filter of water and wastes Essential natural resource
  • SOIL: Make it Work for You! Soil Forming Factors Parent Material Topography (The first four factors over) Time Climate Biota These five factors work together to create a unique soil profile made of layers called horizons.
  • SOIL: Make it Work for You!
    • Each discipline defines soil in a different way, depending on how soil affects it.
    • “ In an engineering sense, soil is the relatively loose agglomerate of mineral and organic materials and sediments found above the bedrock.”
        • R.D. Holtz and W.D. Kovacs (1981)
    What is “Soil?”
    • Physical Characteristics
      • Soil Texture, Consistency, & Structure
      • Soil Compaction (Bulk Density)
      • Soil Moisture
    • Nutrient Characteristics (Soil Chemistry)
      • Chemical bonding
      • pH
      • Cation Exchange Capacity (CEC)
      • Nutrient Availability
    SOIL: Make it Work for You!
    • Texture: the mineral components
    • Consistency & Structure: How the mineral components are put together
    • Bulk Density
    • Soil Moisture
    SOIL: Make it Work for You! Physical Characteristics of Soil:
  • SOIL: Make it Work for You!
    • Soil Texture:
      • The way the soil “feels” is called the soil texture.
      • Soil texture depends on the amount of each size of mineral particles in the soil.
      • Sand, silt, and clay are names that describe the size of individual mineral particles in the soil.
        • Sand are the largest particles and they fell “gritty”
        • Silt are medium sized, and they feel soft, silky or “floury”
        • Clay are the smallest sized particles, and they feel “sticky”
  • SOIL: Make it Work for You! Soil Texture: Relative Size Comparison of Soil Particles frisbee Silt (feels floury) dime Clay (feels sticky) (0.05 - 0.002 mm, USDA) (0.02 - 0.002 mm, ISSS) (< 0.002 mm, USDA) (< 0.002 mm, ISSS) beachball Sand (feels gritty) (2.00 - 0.05 mm, USDA) (2.00 - 0.02 mm, ISSS)
  • SOIL: Make it Work for You! Triangle Key: S = sand or sandy Si = silt or silty C = clay L = loam or loamy Soil Texture Triangle SiCL % Sand % Silt % Clay S LS SL L SiL Si CL SiC C SC SCL 0 100 100 100 0 0
  • SOIL: Make it Work for You!
    • Soils are more cohesive when they have more fine particles (Clays).
    • Soils are more loose when the have more coarse particles (Sand).
    • Different combinations of coarse and fine contents produce different soil textures.
    • A loam is a mixture of sand, silt and clay: sandy clay loam is best in landscapes.
    • Many other inclusions, such as cobbles, boulders.
    Effects of Soil Texture:
    • Soil Consistency
      • Describes the general organization of the soil.
      • Hold a moist sample between the thumb and forefinger, and gently squeeze it until it falls apart.
      • The soil is classified by the following categories
        • Loose: You have trouble picking out a single sample and the structure falls apart before you handle it.
        • Friable: The sample breaks with a small amount of pressure.
        • Firm: The sample breaks when you apply a good amount of pressure and dents your fingers before it breaks.
        • Extremely Firm: The sample can't be crushed with your fingers (you need a hammer!).
    SOIL: Make it Work for You!
  • SOIL: Make it Work for You! Soil Consistence Loose* Extremely Firm Firm Friable * Soils with “single grained” structure always have loose consistence.
    • With Structure:
      • Granular
      • Blocky
      • Platy
      • Prismatic
      • Columnar
    • Without Structure
      • Single Grained
      • Massive
    SOIL: Make it Work for You! Soil Structure: the shape that the soil takes based on its physical and chemical properties. Possible choices of soil structure are:
    • With Structure:
    • Without Structure
      • Single Grained:
        • beach sand
      • Massive
        • solid mass with no shape
    SOIL: Make it Work for You! Soil Structure:
  • SOIL: Make it Work for You! Soil Structure: with Structure Granular Blocky Prismatic Columnar Platy
  • SOIL: Make it Work for You! Single Grained Massive Soil Structure: without Structure
  • SOIL: Make it Work for You! Bulk Density: a measure of soil compaction To calculate Bulk Density: 1 cm. (so, there is 1 cubic centimeter of soil) Sample is made of Solids and Pore Spaces 1.33 gms. Volume = 1 cm 3 Weight = 1.33 gms Bulk Density = 1.33 1 Bulk Density = 1.33 gms / cm 3 Bulk Density = Weight of Soil Volume of Soil
  • SOIL: Make it Work for You! Bulk Density & Compaction Zones 8 inches 1.43 0 inches 7 inches 9 inches 10 inches Depth Bulk Density (grams / cm 3 1.90 1.87 1.84 1.80 1.60 Plow Layer Compacted Zone Uncompacted subsoil
  • SOIL: Make it Work for You! Basic Soil Components Soil Particles: Mineral and Organic Pore Spaces: location of air and water
    • Soil Moisture: some terms and concepts
      • Field Capacity : water that remains in soil beyond the effects of gravity.
      • Permanent Wilting Percentage : amount of water after the permanent wilting point is reached.
      • Available Water : amount of water in the soil between the field capacity and the permanent wilting percentage.
    SOIL: Make it Work for You!
  • SOIL: Make it Work for You! Relationship between soil texture and water availability Sand Sandy Loam Silt Loam Clay Loam Clay Inches of Water Per ft. of Soil 1 2 3 4 Permanent Wilting Percentage Field Capacity Available Water
  • SOIL: Make it Work for You! At Saturation At “Available Water Soil at Different Moisture Levels: Pore Space Water on soil particle surface Pore Spaces are filled with water
  • SOIL: Make it Work for You! Soil at Different Moisture Levels: At Permanent Wilt Compacted No water remains attached to soil particles Pore spaces are collapsed
  • Compacted Zone Impermeable Layer SOIL: Make it Work for You! H 2 O H 2 O Non-Compacted Compacted
  • Sand Over Clay Impermeable Layer SOIL: Make it Work for You! H 2 O H 2 O
  • SOIL: Make it Work for You! Perched Water Table Clay Over Sand H 2 O H 2 O
    • Wet & Dry Layers
    SOIL: Make it Work for You! Soil Sandwiches H 2 O H 2 O
    • Patchy Soil Moisture
    SOIL: Make it Work for You! Soil Salads H 2 O H 2 O
  • Summary of Water Movement:
    • Rate depends on:
      • pore space (structure) and consitence
      • particle sizes (texture) and particle size distribution.
    • Changes in bulk density:
      • changes water movement (e.g. compaction).
      • may result in perched water tables through creating an impermeable layer.
    SOIL: Make it Work for You!
  • Surface Drainage (Run-Off)
    • Severity of slopes
    • Angle and length of slopes
    • Soil or surface type
    • Presence or absence of vegetation
    • Total surface area of drainage basin
      • Must include structural surface area
      • Structures modify soil saturation, contact areas, and volume contact/unit area
    SOIL: Make it Work for You!
    • Divert run-off from adjacent sites
    • Stabilize slopes with synthetic materials, mulches or vegetation
    • Break up straight line flows, slows velocity
    • Construct sediment fences
    • Line drainage channels with coarse aggregates
    • Contoured beds and or terracing
    • Re-vegetation mats
      • Organic vs. synthetics
      • Run strips parallel to slope
    • Soil modifications;
      • Replace high bulk density soils
      • Incorporate OM or aggregates
      • Break up soil surface crusts
    SOIL: Make it Work for You! Controlling Surface Drainage
  • Altering Subsurface Drainage
    • Deep plowing (sub-soiling) can damage tree roots where landscape is established, utilities, impractical for small sites
    • Avoid abrupt changes in soil type
    • Incorporate OM or large quantities of aggregates
    • Huge variety of drains
    SOIL: Make it Work for You!
    • Large Subsurface Drains
      • Concrete pipes
        • Usually for heavy traffic or very large drains
        • High handling and transportation costs
      • Large diameter - 12” to 24” diameter metal culverts
        • Preferred under vehicular traffic
        • Damaged ends hinder linking
        • Expensive
    • Smaller Subsurface Drains
      • Ceramic tiles, out moded
      • Corrugated plastic pipe
        • Cheap, light, flexible
        • Perforated - areas of collection of release
        • Non-perforated - transport areas
      • Avoid clods contacting during installation
        • Cover on 3 to 4 sides with 3” to 4” of aggregates
        • Cover with back-fill, preferably 12”+
          • Topsoil in non-roads, road bed material in traffic areas
    SOIL: Make it Work for You!
  • French Drains
    • Old-fashioned, but very effective
    • Numerous variations;
      • With or without pipes
      • Covered or exposed
    • Often connected to the surface with water permeable material
    • Essentially a trench filled with aggregates
      • Always slope to a lower elevation!
      • Very useful for draining contained planting sites
    SOIL: Make it Work for You!
  • SOIL: Make it Work for You!
    • Horizon “A” = topsoil
      • Specified by texture, OM content, available nutrients and drainage characteristics.
      • Critical to landscape success.
      • Should be removed prior to construction and stock piled on site
        • Incorporate 1/3 into sub-soils after construction to create smoother transition zone
        • Sharp transition between topsoil and subsoil creates perched water tables.
    • Horizon “B” = transition zone
      • Constitutes much of the exposed soil in areas where construction has occurred and in some formerly cultivated portions of Ohio
    • Horizon “C” = true subsoil
      • Little or no soil development.
      • Often contains accumulated soluble salts, lime, etc. beneath cultivated areas.
    Soil Horizons:
  • SOIL: Make it Work for You! Characterization and Sampling Options Soil Pit Exposed Profile (road cut)
    • Chemical bonding
    • pH
    • Nutrient Availability
    • Cation Exchange Capacity (CEC)
    SOIL: Make it Work for You! Soil Chemistry
    • What is “chemistry?”
      • Elements: the simplest kind of matter. They cannot be broken down into anything simpler.
      • Elements can exist alone. Nitrogen (N), Phosphorus (P), Potassium (K), Oxygen (O), are elements and they can be made to exist alone, but in nature they seldom do.
      • Elements tend to combine with each other. These are called “compounds.” When they combine, it’s called a “chemical reaction.”
    SOIL: Make it Work for You!
    • What is “chemistry?”
      • Chemistry is the study of the “how” and “why” elements combine, and break apart, through chemical reactions.
      • Soil Chemistry is simply studying how and why compounds are formed and broken apart in the soil, and how these chemical reactions affect plants.
    SOIL: Make it Work for You!
  • SOIL: Make it Work for You! Chemistry Made Simple: The Atom Hydrogen - The Nucleus = positive charge The Electron = negative charge (+)
  • SOIL: Make it Work for You! Chemistry Made Simple: The Atom Hydrogen (+) - The Nucleus = positive charge
  • SOIL: Make it Work for You! A Water Molecule H 2 O Hydrogen Hydrogen Oxygen (+) (+) (+)
    • What happens when an atom has too many electrons?
      • It has a negative charge ( - )
      • These atoms are called: anions
    • What happens when an atom doesn’t have enough electrons?
      • It has a positive charge (+)
      • These atoms are called: cations
    SOIL: Make it Work for You!
    • What happens when an anion meets a cation?
      • Anions have a negative charge (-):
      • Cations have a positive charge (+):
      • When they meet, they combine to become a molecule, the simplest compound:
      • NaCl (sodium chloride = salt).
    SOIL: Make it Work for You! Chlorine: Cl - Sodium: Na +
  • SOIL: Make it Work for You! Common soil cations and anions, their chemical symbols and ionic forms
  • SOIL: Make it Work for You! The Chemistry of Clay: Clay Particle - - - - - - - - - - - - - - - - - - - - - - - - - - Clay particles carry negative charges
  • SOIL: Make it Work for You! With Magnets - - + - Unlikes Attract Likes Repel In Soil + - + + CLAY NH 4 + Ammonium CLAY K+ Potasium CLAY NO 3 - Nitrate
    • Water ionizes: it falls apart into ions.
    • H 2 O  H + + OH -
    • Called the self ionization of water.
    • Only a small amount.
    SOIL: Make it Work for You! The Strange Properties of Water:
    • It’s simply a measure of the relative amount of H + ions
    • In the soil, it is driven by the ionization of water: H 2 O  H + + OH -
    • We us pH to measure the acidity or the alkalinity (basicity) of a solution (a soil solution)
    SOIL: Make it Work for You! What is pH?:
  • SOIL: Make it Work for You!
  • Possible pH Ranges Under Natural Soil Conditions black walnut: 6.0-8.0 Most desirable carrot: 5.5-7.0 cucumber: 5.5-7.0 spinach: 6.0-7.5 tomato: 5.5-7.5 white pine: 4.5-6.0 Very strong Strong Moderate Slight Slight Moderate Strong Very strong Neutral Acid Basic 3 4 5 6 7 8 9 10 11 1 2 12 13 14 Most agricultural soils Extreme pH range for most mineral soils cranberry:4.2-5.0 apple: 5.0-6.5
  • SOIL: Make it Work for You! - - - - - - - - - - - - - - - Al +3 - - - K + Clay Particle Soil reactions in neutral to high (alkaline) pH conditions Clay and organic particles have a negative charge - - - - Mg +2 H + Mg +2 K + H + Ca +2 Ca +2 PO 4 -3 NO 3 - NO 3 -
  • SOIL: Make it Work for You! Soil reactions in low (acid) pH conditions Clay and organic particles have a negative charge - - - - H + H + Al +3 K + H + Al +3 Al +3 PO 4 -3 - - - - - - - - - - - - - - - Al +3 - - - K + Clay Particle NO 3 - NO 3 -
    • Soil Texture and physical nature of the soil
    • Water availability:
      • soil texture
      • bulk density
    • Soil Chemistry:
      • Charged elements / molecules & soil particles
      • pH and nutrients
    SOIL: Make it Work for You! Physical and Chemical Characteristics of Soil: what does it all mean to you?