Reminder 1:

Your 5-10 photos are due today !

…most of you already have them

Also, make sure you have 5-10 photosfor your longer Plant-Report !

Worth 5 Points !

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

Pages41-58

Page153

There are other minerals that are required by animals (but not plants):

SodiumIodine*

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

Limiting Factor is Nitrogen

Now, Limiting FactorIs Potassiumadd nitrogen

Factors For Optimal Plant Growth *

p. 782

MostOften

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 needmore 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 horsesit cause tremors & lack of

coordination (‘loco’ is spanishfor 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

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!

Chernobyl Nuclear Power Accident, 1986

Lead Pollution from leaded-gas, lead-paints, factories

Darker color = more lead

Plants are also being ‘genetically engineered’ to absorbmore 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 Here12:10

Bacteria Symbiotic Root Nodules = Nitrogen-fixing bacteria living inside specialized root structures

Only members of Legume Family (pea, bean, lentils, clover, alfalfa, soybean, peanut, etc.)

*

…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

One earthworm digests 1 ton of soil per year

• Aerates soil• Recycles nutrients

Castings

Giant earthworm (Australia)

*

3) Soil Texture:

“The relative concentrations of Sand, Silt, Clay”

Sand = .02 - 2 mm diameterSilt = .002 - .02 mmClay = less than .002 mm

Three Factors that can affect plant uptake of nutrients:

*

Joke

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 moldedinto any shape you want…

…and when it dries doesn’t“crack”….that shows how fewair/water spaces there are.

*

Clay isNegatively-charged....

…so attractsPositively-chargedminerals (cations).

This represent a‘storage facility’ for

cations.

*

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Look at all of the Cations required by plants

(and animals)!

*

Advantages of clay soil:

-good water-holding capacity (for what 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

*

Joke

Silt

…is really just eroded sand……has less of the advantages of sand,

and still low water- & nutrient-holding capacity

*

Best type of soilSoil Texture

Triangle*

Best type of soilSoil 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 doneby the Louisville

Sewer District, too!

What can plants do to protect themselves from being attacked by:

Animals (insects, mammals, birds, fish, etc.)Bacteria

Fungi