Chapter 3 Flashcards
(50 cards)
Material phase that in soil is mostly minerals and some humus
Roughly half of the soil volume
Gives nutrients and anchor to plants
Solid phase
Material phases in soil found between solid particles
Other half of soil volume
Ratio varies
Liquid and gas phases
Mineral particles classified by size
Soil separates
> 2 mm in diameter
Coarse earth
0.05 - 2.00 mm
Sand
0.002 - 0.05 mm
Silt
< 0.002 mm
Clay
Provides framework and stability in soil mixture
Easily eroded on its own
Mostly quartz (resistant to breakdown)
Small amount of nutritious minerals (ex. feldspar)
Mostly spherical grains, angularity depends on amount of rolling in water
Sand
Too small to see grains with naked eye
Smooth feel, not sticky
Suspended in fast flowing water, drops in slow flowing
Wind carries it when disturbed by sand
Spherical grains
Majority of parent material in loess
Similar minerals as sand
Silt
Very fine
High surface area on grains per volume
Made of secondary minerals derived from original rock by drastic alteration or recrystallization of weathered products
Flat plate-like shaped grains
Differentiated by arrangement of chemical elements
Clay
< 0.0001 mm
Colloidal clay
How firm or coarse
General ratio of sand/silt/clay
Soil texture
Texture when soil is mostly sand
Coarse
Texture when soil is mostly clay
Fine
Texture of soil when it’s influenced by more than one soil separate
Medium
Instrument that suspends soil in water to measure the density of each separate
Determines ratio of sand/silt/clay
Hydrometer
Soil with balanced amount of all sand, silt, and clay
Roughly 20% clay, 40% silt, 40% sand
Loam
Arrangement of soil particles in an aggregate
Soil structure
Unit of soil structure
Aggregates/peds
The 5 types of soil structure
-granular
-platy
-blocky
-prismatic
-columnar
The properties that make clay and humus act like glue in soil structures
-small
-high in surface area
-have electrical charges
Aggregates are mostly spherical
Generally porous, crumb-like texture
Acts like a sponge
Found commonly in dark surface soil
Some clay and plenty of humus
Ideal structure for farming
Granular
Aggregates are shaped like long, flat sheets that stack on top of each other
Restricts water percolation because of a lack of vertical pores
Platy structure
Cube shaped aggregates
Decent water percolation
Sharp edges when clay heavy, rounded edges when not
Most common in humid forests
Blocky structure
