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Soils 2012. Steven Bradley. Sand [Rough & Fine] Silt Clay. Soil Particles. Sand: Basketball Silt: Baseball Clay: Aspirin. Soil Particle Size. % Sand, Silt, and Clay. Soil Texture. The Soil Texture Triangle. Step 1. Step 2. Step 3. “R Horizon”. Soil Horizons.
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Soils 2012 Steven Bradley
Sand [Rough & Fine] • Silt • Clay Soil Particles
Sand: Basketball Silt: Baseball Clay: Aspirin Soil Particle Size
% Sand, Silt, and Clay Soil Texture
“R Horizon” Soil Horizons
O: Decomp & Plants • A: “Topsoil” • E: Eluvial; leeched • B: Subsoil; where leeched materials go • C: Substratum • R: Bedrock Horizons (cont.)
Composition of Natural Soil, by weight Composition of Compacted Soil, by weight Compacted and Natural Soil
The capacity of soils to hold water available for use by most plants • Used for irrigation schedules Available Water Capacity
The depth that roots can penetrate through a soil down to a root restrictive layer Effective Rooting Depth
3 Types: • Gully • Rill • Sheet Erosion
Water accumulates • Recurs in channels • Can become deep Gully Erosion
Numerous and random • Small • Usually occurs on recently cultivated soil Rill Erosion
Uniform • Thin layers • Usually by rainfall Sheet Erosion
Wet enough to promote plant growth • Indicates wetlands Hydric Soils
ACEMOR • Alluvium [streams] • Colluvium [gravity] • Eolian [wind] • Marine Sediments [sea/tide] • Organic Deposits [decomposition] • Residuum [bedrock] Parent Materials
Parent Material • Climate • Living Organisms • Landscape Position • Time Soil Forming Factors
Additions [organic, deposits] • Losses [Leeching, erosion] • Translocations [water] • Transformations [i.e. rust] Soil Formation
Yield per acre • Irrigated & NonIrrigated Soil Productivity
Infiltration • Percolation • Permiation Water Movement
Organic matter = Dark • Iron = Brown-Yellow-Red • Oxidation = Blue/Green • Brown/Gray = Wet, Saturated Soil Color
Granular [spherical] • Platy [laminated] • Blocky [cube] • Columnar [rounded top] • Prismatic [vertical] Structure
Soils act like… • Sponges • Faucets • Supermarkets • Filters • Traps Soil Functions
Unoccupied spaces in soil • Clay: Not very porous • Sand: Very porous Porosity
Quality of soil that allows movement Permeability
Losing all/part of the upper soil horizon Truncation
Underground supplies of water Water Table