ESS Exam 1

• What is soil made out of?


  3% Organic Material

  25% Water

  25% Air

  47% Mineral (Sand, Silt, and Clay)
• What does soil do?


  Serves as a media for plant growth

  Modifies the atmosphere by emitting/absorbing gases

  Provides a habitat for animals

  Absorbs, holds, purifies, and alters water

  Cycles nutrients

  Serves as an engineering media for construction
• The Pedon


  Smallest 3D body of soil that allows determination of all soil properties of that soil
• Profiles


  Cross sectional cut vertically, every pedon has a profile
• List The Horizon Orders


  O, A, E, B, C, R

  Oreos Are Everything Because Cookies Remain
• O Horizon


  Organic surface layer
• A Horizon


  Mineral horizon
• E Horizon


  Eluvial horizon, loss of organic matter, lots of clay, iron, and aluminum
• B Horizon


  Illuvial horizon, subsurface horizon of clay/iron
• C Horizon


  Parent material, unweathered and unconsolidated material
• R Horizon


  Consolidated bedrock
• What determines soil color?


  Munsell Color Notation
• Hue


  Spectral color of the rainbow, 10YR=10 Yellow: 1 Red
• Value


  Lightness or darkness 0=black 10=white
• Chroma


  Brightness or purity, amount of grey added

  1=high grey, low purity

  10=low grey, high purity
• Matrix


  Main color
• Mottle


  The color added in
• What causes grey colors in soil?


  Drainage problems, iron oxidation
• Redox Features


  Well Drained: >30"

  Moderately Well Drained: 18-20"

  Somewhat Poorly Drained: 10-18"

  Poorly Drained: 10-18" grey matrix with brown mottles

  Very Poorly Drained: Grey to surface
• What does soil texture not include?


  Material over 2mm in diameter (gravel or rocks)

  Organic Material
• Is soil texture a permanent characteristic?

  YES
• Sand


  0.05-2mm

  Single grained, gritty
• Silt


  0.002-0.05mm

  Smooth, floury feel
• Clay


  <0.002mm

  Stiffy, sticky
• Loam


  Good mixture of all 3 particles
• Soil Textures


  Silt, silt loam, loam, silty clay loam, clay loam, silty clay, clay, sandy clay, sandy clay loam, sandy loam, loamy sand, sand
• Granular


  Cookie crumb texture of less than 0.5 cm found where roots grow

  (A Horizon)
• Blocky


  Irregular blocks of 1.5-5.0cm

  (B Horizon)

  Angular Blocky- Sharp edges

  Subangular Blocky- More rounded edges
• Prismatic


  Vertical columns of soil found in lower horizons

  (B but uncommon)
• Columnar


  Vertical columns of soil with a salt cap, found in arid climates

  (B but uncommon)
• Platy


  Thin, flat plates of soil that lie horizontally that are found in compacted soils

  (Rare but can be found in A)
• Single Grained


  Broken into individual particles that do not stick together, found in sandy soils

  (C Horizon)
• Structureless, single grained


  No cohesion (beach sand)

  (C Horizon)
• Structureless, massive


  All primary separates are cemented or bonded together in one mass without any natural planes of weakness

  (C Horizon)
• Why is structure important?

  Helps determine drainage

  Aeration of subsoil

  Influences erosion

  Rooting medium
• Solid/Pore space relations


  Water: 1g/cm^3

  Pine: 0.7g/cm^3

  Quartz: 2.65g/cm^3

  Steel: 7.7g/cm^3
• Particle Density (pd)


  pd= mass of dry soil (g)/volume of soil solids (cm^3)

  v=pir^2h

  2.65g/cm^3
• Bulk Density (pb)


  pb= mass of dry soil (g)/ total soil volume (cm^3)

  Bulk density increases with depth

  Typical ranges from 1.1-1.6 g/cm^3
• Porosity


  E=1-bulk density (g/cm^3)/ particle density (g/cm^3)
• Factors effecting Bulk Density


  Coarse>Fine

  Subsurface horizons>surface horizons

  High organic matter=lower bulk density

  Good structure<poor structure

  Traffic increases pb