Reminder 1:
Your 5-10 photos are due today !
…most of you already have them
Worth 5 Points !
Also, make sure you have 5-10 photos
for your longer Plant-Report !
Reminder 2:
Exam-3 is next Friday!
Chapter 37 (all)
Chapter 38 (pp. 781-784, 787-792) and
related pages on water, chemistry, etc.
Chapter 39 (pp. 795-801)
…this is what we will be covering the next three lectures
Reminder 3 :
Office Visits need to be completed
by next Thursday!
…about 1/3 of class is finished
..only takes about a half-hour.
…e-mail for appointments.
Worth 5 Points !
Announcement:
Lab Next Week = Field Trip
….to Louisville Nature Preserve !
…so dress appropriately
Chapter 38 -
Plant Nutrition
Joke
p. 782
Pages
41-58
Page
153
*
There are other minerals that are
required by animals (but not plants):
Sodium
Iodine*
Chromium*
Selenium*
Cobalt*
Fluorine
* note that some of these can occur as radioactive isotopes
Typical example of Nitrogen Deficiency
‘Wooden Barrel Model’
demonstrating the
Principle of Limiting Factors
of plant growth
Factors For Optimal Plant Growth
Limiting Factor is
Nitrogen
add nitrogen
Now, Limiting Factor
Is Potassium
*
p. 782
Most
Often
Needed
*
Numbers = % Fertilizer Weight
Seeds have a complete supply of nutrients
Early growth depends a lot on Nitrogen
Root growth depends more
on Phosphorus & Potassium
Ginseng
Flowers & Fruits also need
more Phosphorus & Potassium
But it really depends on species
Plants absorb just about any mineral
elements that happen to be in the soil…
*
Some plants are even “Hyperaccumulators”
(absorbing more than 100x more chemical
than what is in the soil)
Locoweed (Colorado)
absorbs selenium.
If eaten by cattle or horses
it cause tremors & lack of
coordination (‘loco’ is spanish
for crazy).
This plant is in the Legume family.
Dr. Chris Anderson, New Zealand,
is mining gold by growing plants
near old gold mines (in the ‘tailing waste’)
He is finding concentrations of gold at
100 ppm in the plants. The trick is simply
to extract the gold cheaply.
‘Phytoremediation’ = using plants to reduce pollution
• Absorbs pollutant and either
metabolizes it (breaking it down) or
at least, concentrates it in the plant.
• Reduces erosion of the polluted soil
by the action of the roots holding on
to the soil.
*
Botanists conducting research on Phytoremediation
old Army Ammunition Dump
St. Paul, Minnesota
Chernobyl Nuclear Power Accident, 1986
Float sunflower plants in a pond
near the nuclear power plant.
The plants absorbed 8000x more
radioactive cesium, and
2000x more radioactive strontium
than what was found in the pond!
Lead Pollution from leaded-gas, lead-paints, factories
Darker color = more lead
Plants are also being ‘genetically engineered’ to absorb
more pollutants…
*
Three Factors that can affect plant uptake of nutrients:
1) Soil pH = concentration of H+
Acid Soils Tend to Have:
•
•
Higher Rainfall
Higher Amounts of Decaying Plant Debris in Soil
Alkaline Soils Tend to Have:
•
•
Lower Rainfall
Lower Amounts of Decaying Plant Debris in Soil
Which type of soil do you think Kentucky has?
In Acidic soils, some minerals become deficient
(like Phosphorus and Molybdenum)
Other minerals are more soluble at higher acidity
and so are taken up more readily by plants:
• Iron
• Zinc
• Manganese
• Magnesium
• Boron
• Copper
One mineral (aluminum) can even become toxic
to the plant because it is so soluble.
The way to overcome acidity =
….add Lime (CaCO3)
(calcium carbonate)
*
*
Three Factors that can affect plant uptake of nutrients:
2) Biological Activity
Three primary examples:
• Fungi
• Bacteria
• Earthworms
Mycorrhizae (fungi)
Announcement:
Lab Next Week = Field Trip
….to Louisville Nature Preserve !
…so dress appropriately
Meet Here
12:10
Symbiotic Root Nodules = Nitrogen-fixing bacteria
living inside specialized root structures
Only members of Legume Family (pea, bean, lentils,
clover, alfalfa, soybean, peanut, etc.)
Bacteria
*
*
…only occurs in certain bacteria
An acre of alfalfa can capture
up to 200 lbs of nitrogen per year !
The “Dead Zone” in the Gulf of Mexico is due to overstimulated
phytoplankton growth (called ‘blooms’). When they die and settle
to bottom of ocean. Their decompostion consumes too much
oxygen, which leads to fish death, etc.
*
Earthworms
*
Giant earthworm (Australia)
One earthworm digests 1 ton of soil per year
• Aerates soil
• Recycles nutrients
Castings
Three Factors that can affect plant uptake of nutrients:
*
3) Soil Texture:
“The relative concentrations
of
Joke
Sand, Silt, Clay”
Sand = .02 - 2 mm diameter
Silt = .002 - .02 mm
Clay = less than .002 mm
Sand
Advantages of sandy soil:
- good aeration
- good drainage
- can’t be compacted
- warms easily
Disadvantages of sandy soil:
- poor water-holding capacity
- poor nutrient-holding capacity
*
Clay
Has few air spaces because
particles fit together so closely
Pure clay can be molded
into any shape you want…
*
…and when it dries doesn’t
“crack”….that shows how few
air/water spaces there are.
*
Clay is
Negatively-charged....
…so attracts
Positively-charged
minerals (cations).
This represent a
‘storage facility’ for
cations.
p. 782
Pages
41-58
Page
153
*
Look at all of the Cations
required by plants
(and animals)!
Advantages of clay soil:
-good water-holding capacity (for what
Joke
water it holds)
- good nutrient-holding capacity
Disadvantages of clay soil:
- poor drainage
- poor aeration
- doesn’t hold onto very much water
- too much compaction
- a “cold” soil
*
Silt
…is really just eroded sand…
…has less of the advantages of sand,
and still low water- & nutrient-holding capacity
*
Best type of soil
Soil Texture
Triangle
*
Best type of soil
Soil Texture
Triangle
What is the % of Sand,
Silt & Clay in Loam?
*
So ideally you want a “Loam Soil”
- good aeration
- good water-holding
- “warm” soil
- holds nutrients well
What do you do if you don’t naturally have Loam Soil?
Add Humus !
(organic matter)
Advantages of Humus:
1) Humus has all the advantages of sand, silt and clay without
all of the disadvantages. For instance, as it decomposes it
becomes negatively-charged (like clay), but it ‘holds-on’
to water very well.
3) It acts as a “time-release fertilizer”…as the organic matter
decays, it’s nutrients get recycled back into the soil.
*
Farmers and Gardeners can add humus by:
1) Adding ground-bark, peat-moss, animal manure,
compost (decaying leaves, grass clippings, etc)….
2) use “Green Manure” = grow plants (clover,
turfgrass) and then plow it into the soil
*
Done a lot by
Chinese farmers…
…but now being done
by the Louisville
Sewer District, too!
What can plants do to protect themselves from being attacked by:
Animals (insects, mammals, birds, fish, etc.)
Bacteria
Fungi