Abiotic Systems Flashcards
What is a soil series? how are they named?
a group of soils originating from the same parent material and having similar soil hrozings in the soil profile, what primary diff between them being their soil texture.
Each soil series is named for a nearby geographic feature
How are soil series divided / organized?
into “phases” based on their difference in texture. The phase name portion of a soil name indicates a feature of the soil that affects management
example of a soil series and phase name
Hagerstown silt loam, 3 to 8 % slopes
Who provides soil maps to the public that can be used to determine the soils series at a given site?
USDA, NRCS - National resoruces conservation service
What is a soil horizon? how are they defined?
a layer parallel to soil surface whose phys, chem, and biological characteristics differ from layers above an dbelow. They are defined by obvious physical features such as color and texture
What is a soil profile?
avertical section of soil that cuts through all its horizons and extending into parent material
All soil is composed of what three components
sand, silt and clay
soil textures vary according to ration of three particles. What composition is loam soil?
primarily composed of sand and silt with a small amoutn of clay
as a rule of thumb equar parts sand and silt in loam soil
How do you read a soil texture triangle?
angles and lines - trace on each angle to find texture class. Each side of triangle is a particle size (clay, silt, sand) and the percentage of that partic in soil is determined by values along each of the three axes
What is soil texture important? what does it determine
determines the soils water holding capacity
determines permeability and workability
impacts plant communities
What is friable soil?
soil with a texture in which large clumps are easily broken apart by hand - but cannot easily be broken apart into (undesirably) small particles (such soils are ideal for agriculture and plant growth)
What is soil porosity?
the void size ebtween particles within a soil, expressed as the percentage of void space in the soil
soil porosity has a direct relationship with…what soil characterisitc
soil permeability
Describe the porosity of sand and why it is as such
High porosity due to large particle size making it difficult to compact (maintained void space)
What is a well graded soil?
soil with a wide range and even distribution of soil particle sized, in which smaller soil particles fill the voids created by larger grains
what is gap-graded soil
soil that contains various particle sizes, but in which gradation between sizes is broken by gaps of some particle sizes
what is uniformly graded soil?
soil consis of a single range of particle sizes
What is permability and what soil dynamics does it impact?
permeabilty is rate at which water moves through soil
it impacts infiltration rates (rate at which water flows into soil through small pores)
and it imapcts percolation: downward movement of water in a soil
What is typically the ratio of highly permeable soils. how can poorly draining soils be amended to improve permeability?
large rations of sand and gravel. add more sand and gravel
What is typ ratio of low permeable soils. How can highly permeable soils be amended to decrease permeabilty
High clay composition. Add clay or peat moss or other highly absorbent organics
What is a hydric soil?
soils with low permeability in areas subject to reguarl moisture - they are heavily saturated with water for long periods of time, rednering the soils anearobic and typ bluish in color
In what design instance are infiltration rates important?
greenstormwater mgmt
in what design instance is percolation particularly important?
septic systems. soils with slow perc rate cannot accomdate septic systems
What is a soil’s bearing capacity?
the measur of a soil to decrease in volume under the pressure of a given weight.
