Soil Science Chapter 14 (R&B) Chapter 14 (Miller) Ch 21 (R&B) Some diagrams and information in this...
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Transcript of Soil Science Chapter 14 (R&B) Chapter 14 (Miller) Ch 21 (R&B) Some diagrams and information in this...
Soil ScienceChapter 14 (R&B)Chapter 14 (Miller)
Ch 21 (R&B)
Some diagrams and information in this presentation have been used and/or modified with permission from Dr. Greg Pillar, Soil & Environmental Science professor at Queens University in Charlotte,
NC.
Your Responsibility!!!SOIL READING GUIDE
Major Soil GroupsSoil Problems
… in both R&B and Miller books!
The Rock CycleIGNEOUS
ROCK
SEDIMENTARYROCK
METAMORPHICROCK
SEDIMENT
Melt
Cool &
Harden
Heat & Pressu
re
Erode & Weather
MAGMA
Erode & W
eather
Com
paction &
Cem
entationMelt
Ero
de &
Wea
ther
MeltH
eat & Pressure
What is SOIL????The relatively thin surface layer of the Earth’s crust consisting of mineral and organic matter.
Soil is not DIRT!
Q: What’s the difference between soil and dirt?
A.Location, location, location!
Dr. Greg Pillar, Queens College
The 5 Soil-Forming Factors
• climate (water, wind, temperature)
• biology (macro- and microorganisms, plants)
• relief (topography)
• parent material (rocks/minerals)
• time
Which is the MOST important??CLIMATE!!!
Formed from parent material (bedrock) that’s slowly broken down through
weathering processes.
What is Soil?How would you describe soil?
Color• Texture
Dr. Greg Pillar, Queens College
Texture
http://www.mii.org
Why the color?http://www.msstate.edu http://www.cs.cmu.edu
Hematite: red
Goethite: yellowish brown
Ferrihydrite:reddish brown
http://www.beg.utexas.edu
Calcite: off white
http://www.pitt.edu
Quartz:white
Organic matter:black
http://www.organicgardeninfo.com
Dr. Greg Pillar, Queens College
• Did you know ??????There are more than 20,000 different soil types in the
United States
Soil Color Variation
….and each one tastes different
Dr. Greg Pillar, Queens College
Dr. Greg Pillar, Queens College
Soil Composition
Water (~25%)
Air (~25%)
Mineral(~45%)
Humus (~5%)
Mineral matter comes from parent material
Air & Water percents are interchangeable
Humus is organic matter!
Soil Composition continued…
Mineral Matter– Provides nutrient
minerals for plants– Provides pore space
for water & air
Older soils are:– More weathered– Lower in certain
essential nutrient minerals
Humus: black/dark brown organic material remaining after
decomposition– Leaf litter, animal dung, & decaying organisms– Increases the soil’s water-holding capacity by
acting like a sponge
POROSITY = amt of soil pore
spaces
Pore spaces occupy ~50% of a soil’s volume– Filled with varying
proportions of soil water and soil air
Soil Air contains the same gases as atmospheric air, but in different proportions.– More CO2 and less O2
(from organism respiration)– Some bacteria need
nitrogen (why??)– The CO2 can accelerate
weathering• CO2 + H2O H2CO3
(carbonic acid)
PorositySoil Composition continued…
Soil Composition continued…
As water infiltrates the soil, it can carry dissolved materials with it.
Leaching: Removal of dissolved materials from the soil by water percolating downward
Illuviation: Deposition of leached material in lower layers– Some substances completely leach out
of the soil because they’re so soluble that they migrate right down to the groundwater.
Observe this Observe this SOIL PROFILESOIL PROFILE through soil through soil
Soil layers are Soil layers are horizonshorizons and and assigned lettersassigned letters
O: Organic materialO: Organic material (may be absent)(may be absent)
A: A: TopsoilTopsoil - Organic - Organic material & mineral material & mineral grainsgrains
E: Leached zoneE: Leached zone (may be absent)(may be absent)
B: B: SubsoilSubsoil – rich in – rich in clay, iron, aluminumclay, iron, aluminum
C: Weathered bedrockC: Weathered bedrock
R: Bedrock R: Bedrock (parent material)(parent material)
Soil Pedon
Dr. Greg Pillar, Queens College
A horizon: organic coatings
B horizon: Iron coatings
C horizon: little coating
Soil Color by Horizon
http://nesoil.com
Fun Fact: It takes 100 to 600 years to
form an inch of topsoil.
Dr. Greg Pillar, Queens College
Soil Color – Variation by Geography
Red soils: Southeast US
Dr. Greg Pillar, Queens College
Soil Color – Variation by Geography
Brown/black soils: Midwest
Dr. Greg Pillar, Queens College
http://www.scienceclarified.com
Soil Color – Variation by Geography
White (gypsum) sands: New Mexico
Dr. Greg Pillar, Queens College
Soil OrganismsEx: bacteria, fungi, algae, microscopic worms, protozoa, plant roots, insects, earthworms, moles, snakes, groundhogs, etc.
Soil organisms provide several Ecosystem Services (important environmental functions).– maintaining soil fertility– preventing soil erosion– breaking down toxic materials– cleansing water– affecting atmospheric composition
Earthworms & Ants: – Cycle minerals– Aerate the soil– Decomposing corpses
contribute organic matter– Assist plants in
reproduction by burying seeds
Mycorrhizae– Symbiotic relationship
between fungi and the roots of vascular plants
– Fungus absorbs nutrients from the soil, and provides it for the plant.
– Plant produces food (photosynthesis), and provides it for the fungus.
Dr.
Gre
g P
illa
r, Q
ueen
s C
olle
ge
Physical Soil
PropertiesPHYSICAL properties:Texture (%sand, silt, clay)
Porosity & PermeabilityIonic Charge
Texture is determined by its % sand, silt, and clay.
Texture determines the type of soil, and the soil’s properties.
Physical Property: Texture
Loam: ideal for
agricultural soil
Soil Components
http://school.discoveryeducation.com
Q: What did the shy pebble say to the big
rock?A. Do you think I’ll ever be a
little boulder?
Dr. Greg Pillar, Queens College
Fine Texture - Clay
https://www.soils.org/lessonsDr. Greg Pillar, Queens College
Course Texture - Sand
https://www.soils.org/lessonsDr. Greg Pillar, Queens College
Soil TextureThe relative portions of sand, silt, and clay-sized particles
Sand: 2.0 – 0.05 mm
Silt: 0.05 – 0.002 mm
Clay: < 0.002 mm
Dr. Greg Pillar, Queens College
B
Soil Texture Diagram PracticeWhat type of soil has:1. 20% clay, 40% silt, 40% sand2. 40% clay, 10% silt, 50% sand3. 30% clay, 60% silt, 10% sand
Find the % of each particle at:
1. A2. B3. C
A
C
60%clay, 20%silt, 20%sand
30%clay, 40%silt, 30%sand
10%clay, 30%silt, 60%sand
(1) Loam(2) Sandy clay(3) Silty clay
loam
Property Sand Silt Clay
Water holding Low Med-high High
Aeration Good Med Poor
Nutrient supplying Poor Med-high High
Pollutant Filtering Low Med High
Why is Soil Texture Important?
SO
IL
TO
UC
HY
FEELY
TIM
E!
Physical: Porosity & Permeability
again… Think it is important??
Definition?– amt of soil pore spaces
Porosity
PermeabilityDefinition?
– ability of water to percolate through
____ porosity = ____ permeability
Physical: Ionic ChargeSoil minerals are often present as ions.Minerals ions are either positively or negatively charged.Clay particles have mostly negative charges on their outer surfaces.– Positively charged mineral ions are attracted
to the soil particles and are held for plant use.• potassium K+ and magnesium Mg2+
– Negatively charged mineral ions are repelled by the soil particles and are washed away from roots.
• nitrate NO3-
Physical Characteristics (review)
Why would 100% sand be undesirable for plants?Why would 100% clay be undesirable for plants?
Answer SAND / SILT / CLAY for the following:– A soil with a lot of _____ would have good drainage,
but poor nutrient-holding characteristics.– A soil with a lot of _____ would have poor drainage,
but good nutrient-holding characteristics.– A soil with a lot of _____ would have low porosity.– A soil with a lot of _____ would have high
permeability.
Two soil cores
Bottom of corecontains filter
paper and cheese cloth
Demonstration
Two unknownliquids
Pollutant #1
Pollutant #2
Demonstration
Liquids passedthrough soil
cores
Leachate collected below
What did you observe?
Demonstration
What happened to the original liquids?
What does a change or no change
in color mean?
To what extent did the soil contribute to
this change?
Soil Soil
Adsorption of Organic Dyes
S+
N
NN
Cl-
O
SO
O
HO
OH
Cl
Cl
Chlorophenol red
Methylene blue
CR-
MB+
Soil
CR-
CR-
CR-
CR-
MB+
MB+
MB+MB+
MB+
MB+
MB+
MB+MB+
MB+
Chemical Property: Acidity
Most soil pH is 4-8. Plants are happiest at 6-7. Plants are affected by soil pH.(1) The solubility of certain nutrient minerals varies
with differences in pH• Low pH = Al & Mn are more soluble, and can be
absorbed in toxic amounts.• High pH = some salts are less soluble, and are less
available to the plants.(2) Soil pH affects the leaching of nutrient minerals.
• Acidic soil = positively charged ions are less soluble and are unavailable for plants.
Soil Conditioners (Lime)CaCO3 or MgCO3
Soil amendment / conditioner… not a fertilizer!Important functions:
1. Corrects soil acidity2. Adds important plant nutrients— Ca & Mg3. Reduces solubility & toxicity of certain elements
in the soil Al, Mn, FeThis toxicity could reduce plant growth under acid conditions.
4. Promotes availability of major plant nutrients. Zn, Cu, P
5. Increases bacterial activity & mutualistic relationships.
http
://w
ww
.wvu
.edu
/~A
gext
en/h
ortc
ult/
turf
/lim
ing.
htm
Soil Conditioners (Compost)
Decayed organic matterReplaces some nutrientsImproves soil structure
– The soil becomes more porous, increasing air circulation and the ability of the soil to absorb and hold moisture.
– Makes the soil more spongy!
http
://w
ww
.wvu
.edu
/~A
gext
en/h
ortc
ult/
turf
/lim
ing.
htm
Wh
at is
So
il?
Soil supports life
http://www.Istockphoto.comL. Clarke and Corbis, 2008
Why is Soil Important?
Fun Fact: 1 teaspoon of good soil contains more than 1 million bacteria!
Fun Fact: There are more living organisms in a cubic foot of soil then
all of China!
Fun Fact: There are more living organisms in a cubic foot of soil then
all of China!
Dr. Greg Pillar, Queens College
Soil stores important nutrients
http://www.lesco.com/
Nitrogen (NH4+) (ammonium)
Potassium (K+)Calcium (Ca2+)
Magnesium (Mg2+)
Phosphorus (P) (PO4-3)
(PO4-3 combines with +charged
particles in soil)
Dr. Greg Pillar, Queens College
Soil Holds Water
Dr. Greg Pillar, Queens College
Soil provides support for buildings
http://www.pbase.comDr. Greg Pillar, Queens College
Soil
Soil filters, buffers, detoxifies….
http://extension.missouri.eduDr. Greg Pillar, Queens College
Inputs/OutputsAre these Soil Inputs or Soil Outputs?
Mass Movements (landslides, etc)Precipitation
Parent MaterialLeaching
InfiltrationUptake by PlantsOrganic Matter
Energy
I
I
I
I
O
I
O
O
Transfers/TransformationsRecall:
Transfers simply MOVE things… they reorganize the soil!
Transformations CHANGE things…they alter the soil’s makeup in some way.
Are these Soil Transfers or Transformations?Decomposition
ErosionDepositionWeathering
Nutrient Cycling
transfer
transfer
transformation
transformation
transformation
Soil PollutionPart II
Chapter 21 (R&B)
Soil Pollution= any physical or chemical change in soil that adversely affects the health of plants and other organisms living in and on it.
Many soil pollutants…– ARE MOBILE!
• move into groundwater, surface water, or air– ARE PERSISTENT!
• seep into tiny cracks called micropores and adhere to the soil particles
– COME FROM FERTILIZERS / PESTICIDES! – CAN ACCUMULATE!
Sustainable Agriculture practices can help…
Salinization of Irrigated SoilIrrigation water soaks through the soil area where the plant roots grow, adding to the existing water. The additional irrigation water causes the underground water-table to rise, bringing salt to the surface. When the irrigated area dries & the underground water table recedes, salt is left on the surface soil. Each time the area is irrigated this salinity process is repeated. ALL IRRIGATION WATER CONTAINS SOME DISSOLVED SALTS.
Salinization of Irrigated Soil
Extra water flows through the soil, mixing w/ salt underground, and bringing it to the surface.
This is in Australia – occurred not from irrigation, but from lack of water-loving plants.
Irrigation salinization is basically the same concept, and the ground would look just like this.
Effects of Salinized Soil on Plants
Normally, the water concentration inside
plant cells is lower than that in the soil resulting
in a net movement of water into the root cell.
When soil contains a high amount of salt, its
relative water concentration can be lower than the water concentration inside
cells. This causes water to move out of the roots into the soil, even when
the soil is wet.
Salinization Lab 1. Answer Prelab Questions2. Gather Materials
– 4 ziploc bags– 20 radish seeds– 4 paper towels
3. Follow instructions on the lab sheet4. BE SURE TO LABEL YOUR BAGS!!!5. Leave them in the box in the front. 6. We’ll inspect their germination
progress and take data over the next week.
Soil RemediationUntil recently, the only way to remove soil contaminants was to…
Why is this a bad thing to do??– Impractical, kills all beneficial
organisms, creates waste, expensive…
DIG IT UP
& INCINERATE IT!
Soil Remediation Techniques
Small Groups: define these, then make a pro/con list. Use your book if necessary.
Dilution– Add lots of water; leach out pollutants
Vapor extraction– Inject air into soil to remove volatile organic
compounds
Bioremediation– Use microorganisms to degrade organic contaminants
(oil, sludge)
Phytoremediation– Use plants to absorb contaminants such as salts or
heavy metals.
Extraction well
Pollutant low sorption potential = not attracted to soil easily washed away
Pollutant high sorption potential = not easily washed
Water
DILUTION: Pump & Treat / Soil Washing
12 - 28
GROUND LEVEL
… But what’s the problem here?
Source Identification and Removal !!!!
12 - 30
How can this problem be fixed???
GROUND LEVEL
Bioremediation (Bioventing)
12 - 32
15.06.b
Activities that Threaten SoilActivities that Threaten Soil
Removing vegetationRemoving vegetation
OvergrazingOvergrazing
Soil contaminationSoil contamination
Erosion ControlErosion Control
• Agricultural: 10% of the worlds best agricultural land damaged due to soil erosion and overuse over last 50 years.
- contour plowing- no-till agriculture (no plowing)- terracing slopes- crop rotation - fallow
Preventing Soil Erosion
Your Responsibility!!!Soil Reading Guide
Major Soil GroupsSoil Problems
Soil Conservation & Regeneration
… in both R&B and Miller books!
Soil Pedon
USDA Soil Profile Activity:http://soils.usda.gov/education/resources/k_12/lessons/profile/