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Section: Plant & Soil Science Unit: Soil Management Lesson Title: Homesite evaluations. 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
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Section: Plant & Soil Science Unit: Soil ManagementLesson Title: Homesite evaluations
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 sandy clay loam (SCL), loam (L), silt loam (SiL), silt (Si) COARSE sand (S), loamy sand (LS), sandy loam (SL)
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
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.
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.
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.
Soil Erosion con’t 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 > 10 foot intervals. Gullies are present and eroding along < 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 <5 foot intervals. Gullies are numerous, well-developed eroding along > 50 % of their length, and are > 100 feet apart. VERY SEVERE Frequent, uncrossable gullies are present. Blow-outs may be numerous and deep. Wind deposits may be present.
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 >5% slopes where soils are not coarse textured.
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
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.
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.
