Section:Plant

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Section Plant Soil Science Unit Soil
ManagementLesson Title Homesite evaluations

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SURFACE TEXTURE

• A certain feel based on their make-up sand, silt,
  and clay,
• Classified as fine, medium, and coarse.

TEXTURE CLASSES FINE clay (C), sandy clay (SC),
clay loam (CL), silty
clay (SiC), silty clay loam (SiCL) MEDIUM sand
y clay loam (SCL), loam (L), silt loam (SiL),
silt (Si) COARSE sand (S),
loamy sand (LS), sandy loam (SL)
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PERMEABILITY

• The speed of internal soil drainage. What areas
  do you think internal drainage affects?

• PERMEABILITY CLASSES
• VERY SLOW Sandy clay, silty clay, and clay
  subsoils
• are plastic and
  sticky when wet and very hard when
• dry
• SLOW Clay loam, sandy clay loam
  and silty clay loam
• subsoils, often
  with subangular blocky or massive
• structure
• MODERATE Sandy loam, loam, silt loam and
  silt subsoils with
• weak prismatic to
  blocky structure
• RAPID Sand and loamy sand
  subsoils

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SOIL DEPTH

• The vertical depth of surface soil plus subsoil
  plus any material to a level that would restrict
  root penetration or inhibit excavation.
• A factor for basements and determining the style
  of the house.
• Soil depth can be very shallow, shallow,
  moderately deep, deep, or very deep.

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SLOPE

• Refers to the inclination of the soil surface,
  and has a direct influence on site drainage.
• Slopes are broken down into
• Gentle, moderate, Strong, Steep, and
• Very Steep.

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EROSION

• Loss of topsoil, airborne soil particles
• Soil piling up in areas not wanted, and severe
  rills and gullies create problems for septic
  systems, landscaping and other uses.
• Must be given a soil erosion rating of slight,
  moderate, severe, very severe.

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Soil Erosion cont

• SOIL EROSION CLASSES
• NONE-SLIGHT There is little or no evidence of
  soil movement. Plants and rocks show little to
  no evidence of pedestalling. Gullies are absent.
• MODERATE Litter is deposited against rocks and
  plant crowns. Small rock and plant pedestals are
  present. Rills ½ to 6 inches deep are present at
  gt 10 foot intervals. Gullies are present and
  eroding along lt 10 of their length.
• SEVERE Soil is deposited against rocks and plant
  crowns. Most rocks and plants are pedestalled
  and plant roots may be exposed. Rills 3 to 6
  inches deep may be present at lt5 foot intervals.
  Gullies are numerous, well-developed eroding
  along gt 50 of their length, and are gt 100 feet
  apart.
• VERY SEVERE Frequent, uncrossable gullies are
  present. Blow-outs may be numerous and deep.
  Wind deposits may be present.

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Surface runoff

• Surface run-off is a problem when water runs off
  of the surface before it goes into the soil.
• Most worried about water running off from above
  and into our home.

• SURFACE RUNOFF CLASSES
• SLOW Occurs on 0-3 slopes and
  coarse textured
• soils.
• MODERATE May occur on 3-5 slopes where soils
  are
• not coarse textured.
• RAPID Usually occurs on gt5 slopes where
  soils
• are not coarse textured.

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Shrink-swell

• Clay percentage determines amount of shrink and
  swell
• Smectite clay will trap water molecules causing
  them to swell to many times their original size,
  shrinking back to their original size when the
  water is removed.
• The horizon having the most clay should be
  considered when determining shrink-swell
  limitations.

• SHRINK-SWELL CLASSES AND LIMITATIONS
• None-slight sand, loamy sand and sandy
  
• loam soils
• Moderate loam, silt loam, silt, clay loam,
  
• sandy clay loam and silty clay loam
  soils
• Severe sandy clay, silty clay and
  clay soils

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Water Table

• Refers to how far it is to available water.
• A shallow water table will cause many problems
  for a home site.
• Look at the time of the year when the water table
  is the closest to the surface.
• Water table depth can be broken into the
  following areas slight, moderate, and severe.

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Flooding

• As home areas become urbanized and the area
  becomes sealed with asphalt or concrete,
  surface runoff increases dramatically.
• If the site is close to a floodplain, the flood
  hazard may also increase.
• Landscape position and proximity to streams are
  flood hazard indicators.
• Our ratings are None, Rare, and Frequent.

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Surface Texture
Building Foundations Landscaping Septic Systems Sewage Lagoons
Fine Severe Severe
Medium None-Slight None-Slight
Coarse Moderate Moderate

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Permeability
Building Foundations Landscaping Septic Systems Sewage Lagoons
Very Slow Severe Very Severe None to Slight
Slow Moderate Severe None to Slight
Moderate None to Slight Moderate Moderate
Rapid Moderate Very Severe Severe
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Soil Depth
Depth (inches) Building Foundation Landscaping Septic Systems Sewage Lagoons
Very Shallow lt10 Very Severe Very Severe Very Severe Very Severe
Shallow 10-20 Severe Severe Very Severe Very Severe
Moderately Deep 20-40 Moderate Moderate Severe Severe
Deep 40-72 None-Slight None-Slight Moderate Moderate
Very Deep gt72 None-Slight None-Slight None-Slight None-Slight
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Slope
Slope () Building Foundation Landscaping Septic Systems Sewage Lagoons
Nearly Level 0-3 None-Slight None-Slight None-Slight None-Slight
Moderate 3-5 None-Slight None-Slight None-Slight Moderate
Strong 5-8 None-Slight None-Slight None-Slight Moderate
Steep 8-15 Moderate Moderate Moderate Severe
Very Steep gt15 Severe Severe Severe Severe
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Erosion
Building Foundations Landscaping Septic Systems Sewage Lagoons
None-Slight None-Slight None-Slight None-Slight None-Slight
Moderate None-Slight None-Slight None-Slight None-Slight
Severe Moderate Moderate Moderate Moderate
Very Severe Severe Severe Severe Severe
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Surface Run-off
Building Foundations Landscaping Septic Systems Sewage Lagoons
Slow Severe None-Slight Severe
Moderate None-Slight None-Slight None-Slight
Rapid None-Slight Severe None-Slight

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Shrink-swell
Building Foundations Landscaping Septic Systems Sewage Lagoons
Low None-Slight None-Slight None-Slight
Moderate Moderate Moderate Moderate
High Severe Severe Severe

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Water Table
Building Foundations Landscaping Septic Systems Sewage Lagoons
Slight gt30 gt24 gt72 gt60
Moderate 18-30 12-24 48-72 40-60
Severe lt18 lt12 lt48 lt40

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Flooding
Building Foundations Landscaping Septic Systems Sewage Lagoons
None None-Slight None-Slight None-Slight None-Slight
Occasional Severe None-Slight Moderate None-Slight
Frequent Severe Severe Severe Severe