Best answer:Environmental Biology Discussion, writing homework

  

Answer & Explanation:That many of our crops are genetically modified and contain genetic material from other species. 1) If you had a choice, would you purchase and consume genetically modified crops? Explain why or why not and support your answers with scientific facts/studies.2) Currently, the U.S. does not require labeling of GMOs. Would you want to see labeling? Explain why or why not.Answer both questions. Write one or two paragraphs for each question. Write what you think, no research. I will upload some reading.
unit_8__food_and_agriculture_.doc

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UNIT 8- FOOD RESOURCES
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UNIT 8 OUTLINE
I.
Food Resources
A.
Food Sources
B.
Forms/Types of Agriculture
1.
Industrialized agriculture
2.
Plantation agriculture
3.
Traditional agriculture
C.
U.S. Agriculture
D.
Traditional Agriculture
1.
Crop Rotation
2.
Polyvarietal cultivation
3.
Intercropping
E.
Green Revolutions
F.
Environmental impacts of raising/catching animals for protein
G.
Global Problems Related to Food Supply
1.
Growing populations
2.
Famine, malnutrition and disease
3.
Contamination of food supply
4.
Loss of fertility in Soil
5.
Loss of Topsoil
6.
Desertification/overuse of water
7.
Salinization of Soil
8.
Pollution – air, soil, water
9.
Use of fossil fuels for food production – greenhouse gases
10. Overfishing
11. Loss of habitat/biodiversity
II.
Soils
A.
What makes up soil?
B.
Human Activities that Impact Soil Quality
1.
Erosion
2.
Overgrazing
3.
Desertification
III. Increasing Food Production
A.
Genetic Engineering
1.
Traditional Crossbreeding/selective breeding
2.
Genetic engineering,
3.
GMF (genetically modified food) has generated much
controversy and fear.
4.
Loss of Genetic Diversity
IV. Pest Control
A.
Why we control pests:
B.
Pesticides
1.
Benefits of Pesticides
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2.
Harmful effects of pesticides
3.
What would be the ideal pesticide?
C.
Alternatives to Pesticides
1.
Cultivation practices
2.
Genetic Engineering
3.
Biological Pest Control
D.
Integrated Pest Management (IPM)
1.
IPM is a mix of strategies
2.
Case Study: Indonesia
3.
Benefits of IPM
4.
Why is IPM not used more widely?
V. Sustainable Agriculture
A.
What is sustainable agriculture?
B.
Organic Agriculture
C.
Locally grown foods (Eat Locally)
VI. Self-Study
A.
Genetically Modified Crops
B.
Disappearance of Honeybees
C.
Video
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I. Food Resources
A. Food Sources
Major food sources on our planet: croplands, rangelands and
fisheries.





Croplands produce approximately 77% of the world’s food.
Primary crops: wheat, corn, and rice
Rangelands produce meat, about 16% of the world’s food.
Primary meat sources: fish, chicken, pigs, and cattle
Oceanic fisheries supply about 7% of the world’s food.
All three systems have increased their food yields since 1950. This
is due to:

Technological advances have increased food production or
harvesting.

More sophisticated farming techniques have been developed.

Expanded use of inorganic chemical fertilizers, irrigation,
pesticides, and high-yield crops has been developed.

Intense farming methods, such as densely populated feedlots,
enclosed breeding/growing pens, and aquaculture ponds or
ocean cages have been implemented.
B. Forms/Types of Agriculture
There are three major forms of agriculture: industrialized
agriculture, plantation agriculture and traditional agriculture.
1. Industrialized agriculture
Industrialized/high-input agriculture produces large quantities of single
crop (monocultures) or livestock animals.
Greater reliance on fossil fuels to drive machinery, water, fertilizers,
and pesticides.
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It is practiced on 25% of cropland, mostly in developed countries.
Produces large numbers of livestock animals
Corporate farmers – represent 5% of US landowners but control ½
nation’s farm acreage compared to 1880s when 40% of population
lived on farms
Feedlots are another example of industrialized agriculture. Feedlots
support large numbers of animals aimed at supporting rapid growth of
fattened animals for meat.
2. Plantation agriculture
Is a form of industrialized agriculture practiced primarily in tropical
developing countries. Not as heavily mechanized as the agriculture
practiced in developed countries such as the U.S.
Cultivate monoculture crops – produce only one kind of crop.
Examples of plantation crops include: bananas, coffee, soybeans, and
sugarcane – many of which are cash crops.
3. Traditional agriculture
Traditional agriculture is characterized by:
 Less of machinery (hence less use of fossil fuels)
 Greater reliance on manual or animal labor
 Less reliance or use of commercial fertilizers as compared to
industrialized farming.
This form of agriculture provides about 20% of the food supply and is
practiced by 42% of the world’s people. It the form of agriculture
mainly practiced by developing countries.
There are several types of traditional agriculture:
Traditional subsistence agriculture: crops typically support a
single farm family’s survival.
Traditional intensive agriculture strives to feed not only the
farmer’s family, but also additional food to sell as income. By using
fertilizer, better irrigation a higher yield is sought.
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Industrialized
agriculture
Shifting
cultivation
Plantation
agriculture
Nomadic
herding
Intensive traditional
agriculture
No
agriculture
Figure 8.1: Forms of agriculture around the world. Note that
industrialized agriculture is the predominant form of agriculture in
North America and Europe.
C. U.S. Agriculture
The U.S. agricultural system produces 17% of the world’s grain but
affects the environment more than any other industry.
 U.S. agriculture is bigger than the automotive, steel, and
housing industries combined in total annual sales.
 Agriculture has doubled crop yield of wheat, corn, and soybeans,
using about the same amount of land since 1940.
 Large agribusinesses (huge corporate/family-owned farms)
control three/fourths of U.S. food production. Labor and resource
costs, with the exception of pesticides, have decreased since
1950.
 This development was possible because of cheap energy. But the
efficiency of U.S. agriculture in terms of energy use is still far
below that of traditional subsistence farming or traditional
intensive farming.
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
Considering the energy used to grow, store, process, package,
transport, refrigerate and cook all plant and animal food, about
ten units of nonrenewable fossil fuel is needed to put one unit of
food energy on the table.
4%
Crops
2%
Livestock
6%
5%
Food processing
Food distribution and
preparation
17% of
total
commercial
energy use
Food
production
Figure 8.2: Energy use in U.S. agriculture. Note the amount of
energy each step in the process uses.
D. Traditional Agriculture
Traditional agriculture, used by people for centuries, turns out to be a
more sustainable form of agriculture. Instead of growing a
monoculture, traditional agriculture focuses of multiple crops. Let’s
look at the different strategies found in traditional agriculture:
1. Crop Rotation
Crop rotation is the alternation of the crop planted in a field from one
season/year to the next (e.g., alternating between corn and
soybeans).
 This helps restore nutrients to soil
 Strategy to avoid pest infestation and disease.
 Helps prevent erosion of topsoil
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Figure 8.3: Crop rotation. Here two different crops are rotated
on different plots year after year.
2. Polyvarietal cultivation
Polyvarietal cultivation is when farmers plant several varieties of the
same crop on a plot.
This reduces chances of losing whole crops to pests or disease because
some varieties may be proving to be more resistant.
3. Intercropping
Intercropping is when the farmer plants rows or two or more
different crops on the same plot at the same time.
Plants can complement each other by retaining more moisture or
providing natural fertilizer in the case of legumes which are nitrogen
fixers.
Intercropping can also reduce erosion by reducing the amount of soil
that blows away with the wind by planting cover crops.
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Figure 8.4: Intercropping. Here different rows of plants are
planted with different crops.
a)
Shelterbelts
Farmers plant rows of fast-growing trees around crop plantings to
provide windbreaks, thereby reducing soil erosion by wind.
Figure 8.5: Shelterbelts. Trees are grown around the plot to
prevent erosion from wind.
b)
Polycultures
Farmers plant many different crops which mature at various times
together.

This strategy provides a sustainable yield of plants at different
times of year and a constant food supply

Weeds have a difficult time establishing themselves and multiple
habitats encourage proliferation of natural predators of pests.
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
Results in less use of herbicides and pesticides.

Low-input polyculture produces higher crop yields than highinput monoculture.
c)
No-till farming
Rather than till the soil, which increases soil erosion, farmers drills
furrow into the soil and seeds are deposited in the hole. This style of
the farming is practiced by nearly half of the acreage farmed in the
U.S.
Figure 8.6: No-till farming.
E. Green Revolutions
Since 1950s agricultural technology has produced what we call “green
revolutions” which include the following:
 Development of selective or genetically engineered crops
 More crops/season, fewer rotations
 Development of fast growing varieties of wheat and rice
 Increase number of crops/year
 Revolutions allow greater yield on smaller plots of land
Many of these newer varieties allow one to grow more crops on
smaller plots of land which is more efficient in the sense of space.
Prevents less use of forests and preserves biodiversity. For example,
India has been able to double its food production since 1960.
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Figure 8.7: IR-8 is a dwarf rice variety that produces higher
yields of rice than traditional strains.
Article: Historical rice varieties and impact on green revolution:
http://www.abc.net.au/science/slab/rice/story.htm
What has been the environmental impact of these “revolutions?”
 Newer high-yield varieties require more intensive use of
fertilizers and pesticides
 Greater use of fossil fuels
 Increased pollution
 Loss of biodiversity (monocultures, limited strains available)
F. Environmental impacts of raising/catching animals for
protein
The harvesting of animals for food also has significant environmental
impacts. The following graph charts the per capita (per person)
amount of protein since 1960. As you can see the consumption of
animal protein per person has more or less risen in the last 45 years.
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Figure 8.8: Consumption of animal protein (per capita) over
time.
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Figure 8.9: Amount of land and water and required for
different protein sources.
THOUGHT QUESTION NO. 1: Based on Figure 8.9, which source
of protein is the most efficient in terms of the amount of land
used/kg of protein?
THOUGHT QUESTION NO. 2: Based on Figure 8.9, which source
of protein is the least efficient in terms of the amount of land
used/kg of protein?
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Figure 8.10: Amount of grain used to support different animals
raised for meat.
G. Global Problems Related to Food Supply
1. Growing populations
Growing populations cause the following impacts:
 Generates more waste
 More consumption of resources
 More disease and malnutrition
 More consumption of fossil fuels to produce food in industrialized
countries.
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2. Famine, malnutrition and disease
Famine often occurs due to droughts/failure of crops and can lead to:
 Malnutrition and disease
 Malnutrition leads to mental and physical retardation in children
 Malnutrition makes people more prone to infectious disease.
3. Contamination of food supply
Contamination of a population’s food supply can come from several
sources:
 Pesticide residues from foods
 Contamination of drinking supply from livestock waste
(bacteria), fertilizers and pesticides.
 Bacterial contamination of meat and vegetables (e.g. salmonella
and E. coli.).
4. Loss of fertility in Soil
Occurs when land is overused beyond what it can sustain.
Farmers will remove crops completely without leaving any plant
material to decompose and fertilize the land (remember the carbon,
nitrogen and phosphorous cycles)
5. Loss of Topsoil
Soil erosion can be caused by overgrazing and unsustainable farming
practices.
Erosion occurs when topsoil is washed away into streams or blown
away by the wind.
In the last 100 years about 1/3 of the topsoil has been lost to erosion.
This leads to desertification in times of drought.
This is what happened in the 1930s in the Midwestern United States
(the Dustbowl).
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Figure 8-11: The Dust Bowl of the 1930s was a result of
unsustainable farming practices and drought. Millions of tons
of precious top soil was lost.
6. Desertification/overuse of water
Overuse of water also causes area to become a man-made desert.
This is caused by spreading urbanization and colonization and its
subsequent increased water use.
Increased water depletion can also result from water-intensive
farming.
In California and Midwest, the water tables are sinking
In areas near shore, withdrawal of water from ground water sources
can leads to salt water intrusion which contaminates water supplies.
7. Salinization of Soil
The salts left behind when irrigation water is not absorbed into the soil
can be left in the topsoil. This is called salinization.
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Loss of crop productivity can result from repeated irrigation, which
produces salt buildup and water logging of plant crops.
Salinization has reduced yields on 20% of the world’s cropland.
Water logging occurs when saline water (from irrigation) envelops the
deep roots of plants. This saline water accumulates underground and
raises the water table.
8. Pollution – air, soil, water
Industrialized farming can release pollutants into our air, soil and
water.
Water: fertilizers, pesticides and animal waste contaminate our water
supplies.
Air: the use of machines in agriculture release air pollutants and
greenhouse gases.
Soil: pesticides can penetrate the soil and reach our groundwater
system.
9. Use of fossil fuels for food production –
greenhouse gases
Industrialized farming results in increased use of fossil fuels which
emits greenhouse gases.
10. Overfishing
Our fisheries are severely depleted because we are taking fish at a
faster rate than can be replenished. The following graph shows the
rise in ocean fish harvesting:
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Figure 8.12: Total fisheries catch since 1950s.
SUPPLEMENTAL READING: Read article on fisheries depletion
in the doc sharing section.
THOUGHT QUESTION NO. 3: What percentage of fish and
seafood populations have already collapsed?
THOUGHT QUESTION NO. 4: How is the term “collapse” defined
in the article?
11. Loss of habitat/biodiversity
Finally, as populations grow more and more land is needed to for
towns/cities, farms and to house livestock. This encroaches on the
habitats of other species and this loss of habitat leads to local
extinction of populations and loss of biodiversity.
Loss of biodiversity can also occur from killing predator populations.
Pollution from farming can also kill local populations.
Also industrialized farming tends to produce monocultures. To date we
have lost dozens of wild crop strains as well as traditional or heirloom
varieties of crops. Therefore, we are losing genetic diversity by raising
only a select variety of crops.
II. Soils
A. What makes up soil?
Soil is a complex mixture of organic and inorganic components. The
uppermost organic layers (litter) and topsoil are the layers of soil that
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are richest in plant nutrients. That is why there is so much concern
about the loss of topsoil because it affects the productivity of the
plants that are grown in the area.
Figure 8.13: Soil is composed of organic and inorganic
materials.
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Figure 8.14: Soil Profile. The O horizon (organic litter layer) and A
horizon (topsoil) are richest in plant nutrients and most vital for
agriculture.
Soil and soil profiles vary from place to place which has implications
for agriculture.
Amazonian rainforest soil – the large amount of rain leaches
nutrients from topsoil out of reach of plant roots. What little nutrients
remain is taken up by lush vegetation, leaving little in soil. Thus when
farmed, Amazonian soil tends to give out after a few years and
farmers must move on and clear a new plot of land.
Kansas prairie soil = the lower rainfall keeps nutrients in topsoil
where plants take them up and recycle them back into soil when they
die. The topsoil in this region is rich and productive as evidenced by
the extensive farming in this part of the U.S.
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B. Human Activities that Impact Soil Quality
1. Erosion
Unfortunately, many human activities are causing soil erosion. Soil
erosion occurs when soil is removed from one location and
transported to another location by the action of wind or water.
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
It is estimated that US soils are eroding 16 times faster than are
forming

Great Plains has lost 1/3 or more of its original topsoil

We have seen reductions in US soil losses since 1980s because
of better farming practices.
Red = high
Orange = very
high
Yellow= moderate
Green= low
Source: US Dept of Agriculture
Figure: 8.15: Vulnerability to wind erosion world map
Causes of soil erosion include:
 Livestock overgrazing
 Deforestation
 Cropland agriculture
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Figure 8.16: Causes of
Soil degradation
Figure 8.17: Example of
erosion on irrigated
cropland.
Ways to prevent soil erosion
Many of the ways we can prevent soil erosion are based on traditional
farming practices, some of which we discussed above. This includes:






Crop rotation
Intercropping
No-till Farming
Shelterbelts
Contour Farming
Terracing
These techniques are exemplified by the photos below:
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Figure 8.18: Farming practices that help prevent erosion.
Contour farming and terracing essentially prevent erosion on sloped
land by farming in strips or terraces to prevent the formation of gullies
and losing large amounts of water flowing downhill.
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2. Overgrazing
Overgrazing can also degrade top soil. We discussed much of this in
the biodiversity lecture and will not repeat it here. Here is a recap of
how overgrazing leads to soil loss and erosion.
Figure 8.19: process of soil degradation resulting from
overgrazing.
Figure 8.20: contrast between
overgrazed and managed land.
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3. Desertification
Desertification is the loss of more than 10% productivity due to soil
erosion, soil compaction, deforestation, overgrazing drought and water
depletion. It is essentially the conversion of once fertile land into a
newly-made desert.
Desertification can expand natural desert areas by creating new ones
in areas that were once fertile.
While desertification can occur from natural causes such as drought,
the major human causes of desertification are: poor farming practices,
overgrazing and overdraft of water (overconsumption of water).
Red = very high
Orange = high
Yellow= moderate
Green= low
Source: US Dept of Agriculture
Figure 8.21: Areas of desertification vulnerability. Note the
areas in red in the United States, Africa and the Middle East.
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III.
Increasing Food Production
A. Genetic Engineering
1. Traditional Crossbreeding/selective breeding
The traditional method by which new varieties of fruits and vegetables
was through cross-breeding which involves the breeding of different
strains or varieties of plants. Plants are crossbred to introduce
traits/genes from one variety or line into a new genetic background.
This involves the breeding closely or distantly related individuals to
produce new crop varieties or lines with desirable properties. For
example a plant variety or strain of tomato that is a good producer
could be crossed with a variety of tomato that had better disease
resistance to introduce better disease-resistance into the line.
Crossbreeding is a 15-year plus process. Sometimes the new varieties
are useful only for a few years; then, pests and diseases reduce the
effectiveness of the new varieties.
2. Genetic engineering,
Genetic engineering, which represents the latest “green revolution”,
involves the insertion of a gene from one organism into the DNA of
another organism in order to create improved strains of crops and
livestock animals. Such organisms are called “Genetically Modified
Organism” or GMOs.
A subset of GMO’s are called transgenic organisms. T …
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