Calculations
What is the equation for VWC?
VWC= water volume (cm3)/ total volume of sample (cm3)
The finest level soil taxonomic group is ___________.
series
Sands and silts are __________ minerals.
primary
What are the four physical properties of soil?
Texture, color, pores/voids, and structure
Do soils with lots of pore space have high or low bulk density?
Low bulk density
What is the equation for bulk density?
Bulk Density= mass/volume
Organic matter comprises about what percentage of the soil?
5%
The most abundant nonsilicates are __________.
oxides
30% clay, 60% silt, and 10% sand; what soil texture is this?
Silty clay loam
Do soils with high organic matter have high or low bulk density?
Low bulk density
What is the VWC of 400 cm3 of soil where the field water weight is 213 g and the oven dry weight is 133 g?
VMC= 20 %
What process leads to the development of the E horizon?
eluviation
Name a specific 2:1 clay mineral.
Montmorillonite
From high to low, categorize each soil texture to its susceptibility to wind erosion.
Silt, sand, clay
What is capillary water?
Water held above the saturated zone
What is the wet bulk density of a 300 cm3 soil core that weighs 433 g (field wet weight)?
BDwet= 1.433 g/cm3
List the four pedogenic processes.
additions, losses, translocation, transformation
Before substitution, a typical tetrahedron is composed of what two elements?
oxygen and silicon
Which grade of soil structure describes “aggregates that separate when soil is disturbed”?
Strong
What are 3 hydrologic soil properties? Hint: multiple right answers
Smaller pore size
More porosity
Lower bulk density
Greater water-holding capacity
Gleying
Mottling
More unavailable water for plants
Core samples were obtained by hand auger with a diameter of 6.35 cm and analyzed by 2 cm depth increments. Calculate bulk density and VWC. See Screen.
See Screen
Spodosols come from the Greek spodos which means ___________.
wood ash
List the three categories of true 2:1 silicate clays.
smectites, micas, vermiculites
Which soil structure is this describing? Indistinct aggregates, blocky with rounded corners, 10 to < 20mm
Weak medium subangular blocky
What are the 3 forces governing soil water potential? And what is the equation?
1. Gravimetric Potential
2. Matric Potential
3. Osmotic (solute) Potential
soil water potential= gravimetric potential + matric potential + osmotic potential