Soils Exam 1 Flashcards
Pedon
A 1X1X1.5 M DEEP UNIT OF SOILIS REFFERED AS A PEDON.
Regolith
Volume of soil between surface and bedrock
Soil functions
- Supports plant life in our biosphere
- Harbors thousands of types of saprophytes (organisms that eat or decompose dead organisms)
- Serves as foundations for homes, industries and highways
- Absorbs harmful contaminants from surface h20
- Filters pathogens/parasites from waste water
Four ways soils support plant life
- Anchor plant roots
- Supply water for plan roots
- Supply air for plant roots
- Furnish roots for plant growth
- Release water with low levels of nutrients
Types of rocks
- Igneous Rocks
- metamorphic rocks
- Sedimentary rocks
Rocks
Collection of minerals
Hydrologic Cycle
Breaks rocks to form soils
Rock + Rain=
The current landscape+soil
Five hills lope position
Summit Shoulder Back slope Foot slope Toe slope
Soil forming processes
- Losses(erosion)
- Additions(deposition)
- Translocation
- Transformation
Soil forming factors
- Parent material
- Topography
- Climate
- Time
- Organisms
Different types of parent materials
- Alluvium-water-river-flood plains
- Colluvium-gravity-foot slope
- Lacustrine-water-lakes-dried up lake beds
- Aeolian-wind-wind blown deposits
- Marine-ocean-exposed ocean deposits
- Glacial till-retreating glaciers-broad glacial plains
- Glacial outwash-melt water from glaciers-areas with in glacial areas
Soil Horizons
- surface
- topsoil
- subsoil
- substratum
- bed rock
Texture
Soils containing large amounts of sand exhibit little plasticity and cannot retain large amounts of water or nutrients. They have large voids (macropores) that readily transport water and air.
Mineral fraction of soils
Sand Silt Clay
Diameter of particles
0.05-2 mm 0.002-0.05 mm <0.002 mm
Soil Color
Useful tool for providing information about other soil properties Organic matter content Soil minerals Seasonal high water tables
Structure
The arrangement of primary soil particles into compound particles or aggregates. The type and grade of structure plays an important role in the movement of water within soils.
Minerals particles having an average diameter>2mmare termed gravel..
and are not used to calculate soil texture
NOT TRUE ABOUT TEXTURAL CLASSES
They are closely related to its color
There are 11
They are related to structure
Dull-gray coloration of an iron-rich mineral soil profile, particularly with increasing depth, indicates
saturation or seasonal water table
The hue of a soil is considered non-existent, and denoted as N, when the:
Chroma is 0
Soil color can be highly indicative of:
- OM content, parent material, and/or degree of seasonal saturation (drainage)
B) Sand content, parent material, and/or calcium content
C) Soil fertility (namely base saturation)
D) OM content and nematode infestation
E) Horizon depth and load-bearing capacity
F) Sand content and shrink-swell characteristics
Redox depletions, localized pockets of soil where anaerobic conditions persist, take on a ‘gley’ color in which chroma is low (less than or equal to 2) and value is typically:
greater than or equal to 4
Which type of soil structure is common in soil horizons dominated by shrinking-swelling clays?
Wedge
Which soil structure most impedes movement of water through the soil?
Massive
Platy
In the majority of upland soil profiles, this component of soil color increases with depth:
Value
The hue of a soil is considered non-existent, and denoted as N, when the:
Chroma is 0
Which type of soil structure is common in soil horizons dominated by shrinking-swelling clays?
Wedge
Soils residing in the ‘sand’ textural class are often specified in construction of important, highly-trafficked turfgrass systems to enhance long-term:
- Infiltration and permeability B) Cation exchange capacity (CEC) C) Erodibility D) Available water holding content E) Shrinking and swelling characteristics
Of the following soil properties, which is least-related to soil texture?
-Soil color B) Permeability C) Soil textural class D) Available water holding content E) Erodibility F) Infiltration G) Shrink-swell characteristic H) Porosity
If you excavated a perfect 3x3x3-cm cube of dry soil and determined it’s mass to be 40 grams, the bulk density of that soil is:
1.48 g/cm3
Imagine you have a pure quartz sand. Furthermore the sand is exactly 50% pore space by volume. Knowing the particle density of quartz to be 2.65 g/cm3, what’s the bulk density of this pure quartz sand?
1.325 g/cm3
You find a steel ring having a 4 cm inner diameter, a height of 1.5 cm, and a mass of 7 grams. Nice find! Imagine you took that ring to the field, packed it with soil, dried it in an oven, and let it cool. Later, you determine the oven-dry soil and ring (together) weigh 30.6 grams. What is the bulk density of the soil you collected?
1.4 g/cm3
A dry soil clod weighs 48 g. When you then tie a string around it, dip it in hot wax, and determine the volume of water it displaces, you realize this dry, water-tight, SOIL CLOD has a volume of 27.5 cm3! Using 2.65 g/cm3 for particle density, what do you estimate the porosity within the soil clod to be?
less than 35%
You find a steel ring having a 8 cm inner diameter, a height of 1.5 cm, and a mass of 32 grams. You feel lucky and want to do the right thing, so you take it to a field, pack it with soil, dry it in an oven, and let it cool. Later, you determine the oven-dry soil and ring (together) weigh 148.9 grams. Using a particle density of 2.65 g/cm3, what do you estimate the porosity of the soil you collected to be?
41.5 %
simplistic
a surface blend of ssc and or organic matter material in witch plans grow
Weathering: Physical Breakdown
expansion/contraction
abrasion
Weathering: Chemical Alteration
decomposition of minerals
hydrolysis
Primary minerals
created with magma deep with in the earth
Secondary minerals
formed at earth surface from chemical(weathering) of primarily minerals
