Exam 3 Flashcards
Definition of Soil
Layer(s) of generally loose mineral and organic material that are affected by chemical, physical, and biological processes at or near the planetary surface and usually holds liquids, gasses, and biota and support plants
Spheres that interact the pedosphere (soils)
-Hydrosphere
-Lithisphere
-Biosphere
-Atmosphere
4 main components of soil
-Minerals
-Air
-Water
-Organic matter
Model of Soil Formation
S=F(cl,o,r,p..)
T
Regolith
Area of soil right above parent material
Chemical weathering is more common in what environment
Hot and wet environment
6 roles of soil
-Habitat
-Construction material, foundation
-Plant growth
-Modify atmosphere
-Control water
-Recycle waste
Three size classes
-Sand (largest)
-Silt
-Clay
Area called the “living skin” of earth
Air, water, rocks, and life interact
Critical zone
Master Horizons and Features
-O:Organic Matter
-A: Organic Matter and Minerals
-E: Eluviation, loss of material
-B: Alteration to parent materal, subsoil
-C: Partial parent material, little alteration, unconsolidated
-R: Actual parent rock, consolidated
Transition Horizons
Horizons that have characterisitics from two different horizons
Denotes the use of two letters AB, BA, etc
Three types of Organic material
-Litter: Fresh material
-Fermented: Beging decomp, still distingushable
-Humic: Origins not distingushible
Four Major Processes of Soil Formation
-Translocation:Material moves up or down the horizon or in and out
-Transformations: decomp and rock weathering
-Additions:Dust
-Losses:Water
Soil Profile vs. Horizon
Profile is a verticle cut into the Earth and has many horizons
Horizon is just one section
Taxonomic soil category that covers the most area, but has the least amount of info
Order
Taxinomic Categories from least information to most
1.Order
2.Suborder
3.Great Group
4.Subgroup
5.Family
6.Series
Subgroup
Divides the Great Group into categories based on atypic characteritics
Its the same soil just a little different
Typic definition
Contains the central characteritic
Would fall between two atypic subgroups
Ex. Between aridic and aquertic would be typic
Entisols
-Recent
-Little to no soil profile development
-Alluvial to sand barrens
Inceptisols
-Young w/ rapid development
-Pacific Northwest and Northeast
Andisols
-Volcanic ash layers
-Near volcano or downwind
-High natural fertility
Gelisols
-Young soil, minimal profile development
-Permafrost
-Not good for ag or development
-Store a lot of carbon
Histosols
-20% organic matter
-Black to Dark Brown
-Developed in wet environments (like wetlands)
Aridisols
-Arid, dry
-Dry year round
-Most common soil in the west
Vertisols
-High clay content
-Creates cracking on surface layer when dry
Mollisols
-Most productive w/o fertillizers
-High organic content
Alfisols
- Aluminum and Iron
-Midwest
-Highly productive
Ultisols
-Subtropical to tropical
-Red to Yellow
-Prone to leeching
-Southeastern US
Spodosols
-Wood Ash
-Acidic
-Pine tree forests, creates the high acid content
Oxisols
-Highly weathered
-High clay content
-Tropics
Effective Precipitation
Precipitation that reaches the regolith
Why is effective precipitation important in soils
The movement of precipitation can bring soluable materials down or break up parent rock
The lack of precipitation may keep certain materials in place
Residual Material
Material that is formed directly from the parent material (bedrock)
Rock Fragments that are transported down
Course and stony
Colluvial debris/material
Alluvial Deposits
-Lowest area comapred to Rsidual and Colluvial
-Deposited Sediment
Hydrolosis
-Water splits into H and O2
-H replaces a cation on the mineral
Biogeochemical weathering
The conversion of primary minerals to secondary minerals and releasing soluable plant nutrients
