Soils Exam II Flashcards
What are the best suited purpose of each USDA land capability class? (I, II, V, and VII)
I - All
II - Intensive cultivation (some limitations)
V - No cultivation, intensive grazing
What are the 12 soil orders?
Andisol, Histosol, Vertisol, Entisol, Inceptisol, Ultisol, Oxisol, Aridisol, Gelisol, Mollisol, Alfisol, Spodosol
Soil order ending in “…ands”
Andisols
Soil order ending in “…ists”
Histosols
Soil order ending in “…erts”
Vertisols
Soil order ending in “…ids”
Aridisols
Soil order ending in “…els”
Gelisol
Soil order ending in “…olls”
Mollisols
Soil order ending in “…alfs”
Alfisols
Soil order ending in “…ods”
Spodosols
What is the bulk density of most mineral soils in temperate regions that are not compacted?
1.2 g/cm3
What is Volumetric water content?
The volume of water per volume of soil
Features of Andisols
Poorly cystaline clays and glass dominated
Volcanic PM
High Water holding capacity
Features of Histosols
20-30% Organic Matter by weight
Not a mineral soil
Features of Vertisols
Rich in clay
Highly susceptible to shrink/swell
Has deep cracks up to several inches wide (when dry)
Features of Entisols
No B horizon
Little or no soil development present
Soil order ending in “…ents”
Entisols
Soil order ending in “…epts”
Inceptisols
Features of Inceptisols
Has weak B horizon
Relatively young soil
Soil order ending in “…ults”
Ultisols
Features of Ultisols
Highly leached and weathered
Acidic forest soils
Quite old soil
Soil order ending in “…oxs”
Oxisols
Features of Oxisols
Contains only Oxide minerals
Not found in WA
Tropic locations
Features of Aridisols
Contains large amounts of CaCO3
Some subsurface horizon development
Dry most of the year
Features of Gelisols
Has permenant permafrost
Not found in WA
Features of Mollisols
Dark, thick A horizon
Grassland locations
Features of Alfisols
Moderately leached
Broadleaf forests
High fertility and water holding capacity
Clay accumulation (Bt)
Features of Spodosols
accumulation of sdsquioxides (Al and Fe)
Bs horizon present
Sandy Coniferous and acidic forests
Channeled Scablands formation
Shaped by catastrophic floods from northern regions
Large eruption about 8000 years ago
Mount Mazama
Define Particle Density
Mass of particles (or solids) per volume of particles (or solids)
Estimated Bulk Density for mineral soil in temperate regions
1.2 g/cm3
Which pores are most important for air movement in soil?
Macropores
Why is good aggregation important?
Increases soil porosity
Increases number of Macropores
Increases easy movement of air and water
What measurement is used to quatify the shrink-swell tendency of soils?
Coefficient of Linear Extensibility (COLE)
What will water do if Soil A = -300kPa and Soil B = -500kPa
Move from soil A to soil B
What components of total water potential effects water flow direction in a saturated Soil?
Gravitational and pressure potential
The components of total water potential
Pressure Potential
Gravitational Potential
Osmotic Potential
Matric Potential
Difference between Adhesion and Cohesion
Adhesion - Attraction of water to soilds
Cohesion - Attraction of water to water
What conditions must be present for Osmotic pressure to also be present?
A semi-premeable membrane and solutes
How to quantify field capacity
Approximately at -30kPa
Moist, well drained soil
How does OM help with compaction?
Reduces compaction
Increases aggregate stability
