Chapter 4 Quiz Flashcards
8 soil physical properties
- soil color
- soil texture
- soil structure
- soil densities
- total porosity
- soil compaction
- soil tilth
- aggregate stability
easiest soil properties to change
color, structure, bulk density, soil porosity, compaction, aggregate stability
what are the two soil densities
bulk density and particle density
bulk density >1.5 g/cm3 =
compacted
organic soil has a bulk density < _____ g/cm3
1
mineral soil has a bulk density > ______ g/cm3
1
particle density =
2.65 g/cm3
the water and air in the soil equals…
total porosity
water has _____ pores
small
air has _____ pores
large
total porosity functions
air movement/circulation and water movement/circulation
total porosity size
macropores, micropores, and mosopores
soil tilth
how easy it is to till
aggregate stability
relates to soil erosion
organic matter is the ____ of aggregates
glue
4 soil color determinants
- mineralogy
- organic matter
- hydrology
- soil chemistry
determining soil color
Munsell Color Chart, hue, chroma, and value
soil colors common in Calloway County
7.5YR and 10YR
10 YR 6/3
10YR =
6=
3=
10YR = hue
6= value
3= chroma
y axis =
value
x axis =
chroma
top right corner
hue
A horizon
mid/low value and low chroma
E horizon
high value and low chroma
B horizon
we don’t know
water table depth can impact…
soil color
soil texture
proportion of sand, silt, or clay in the soil
soil separate
three categories based on particle size
largest particle size =
smallest particle size =
l = sand
s = clay
soil texture importance
related to porosity and surface area
__ texture classes
12
texture-by-feel
field texture id method
hydrometer
lab texture id method
sedimentation
texture id method
soil must have a particle diameter…
< 2mm
sand diameter
2.0 - 0.05mm
sand dominant material
quartz
silt diameter
0.05-0.002mm
silt dominant materials
quartz / feldspar / mica
clay diameter
<0.002mm
clay dominant materials
secondary minerals
soil texture importance (4)
- provides water flow potential
- influences water holding capacity
- indicates fertility potential
- indicates suitability for urban purposes, such as buildings
sand characteristics (4)
- low specific surface area
- gritty
- resists compaction and increases porosity
- rapid infiltration and drainage
specific surface area means…
how well soil can absorb water and nutrients
silt characteristics (4)
- high specific surface area
- silky and smooth
- promotes water retention and air circulation
- moderate infiltration
clay characteristics (6)
- large surface area
- small pores
- high water holding capacity
- increased water retention
- slow infiltration and poor drainage
- sticky and easily compacted
small clay particles are…
colloids
USDA textural classes
sandy soils (coarse), loamy soils (medium), clayey soils (fine)
soil porosity
the total volume of soil pores and the distribution of pore sizes
ideal soil porosity is…
50%
soil compaction = soil porosity…
> 50%
sand has ____ # or % of pores but _______ size
less; bigger
clay has ____ # or % of pores but _______ size
more; smaller
Western KY has
silt loam
____: large particles = large pore spaces
sand
____: small particles = small pore spaces
clay
more specific surface area is better because…
it can absorb more nutrients
specific surface area formula
surface area / mass (label cm2/g)
clay is _________ in the texture triangle
horizontal
