pressure and misery, which he defined as famine, poverty,

kayakjokeMechanics

Feb 22, 2014 (3 years and 5 months ago)

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Unit
4


Agriculture

Thomas Robert Malthus:
An English political economist,
explained in simple terms the connection between population
pressure and misery, which he defined as famine, poverty,
disease and war.

(from his 1798 book,
An Essay on the Principle of Population
.)

Ch.11


Food is necessary for human
existence.


Human population, if not
checked, tends to grow faster
than the power in the earth to
produce subsistence.


The effects of these two unequal
powers must be kept equal.


Misery is the mechanism that
balances human requirements
and available resources.

Unit
4


Agriculture

The Human
-
Induced Biome:
Agroecosystems

Ch.11


11% of the land area in the world is used for agriculture
(about the size of North & South America combined)



A rising % of
NPP (
Net
Primary
Production
) is
being
converted from
natural systems
to support
people

Unit
4


Agriculture

Food and Population Increase

Ch.11


As populations increase, the amount of land under cultivation
MUST also increase


We usually see food shortages when pop’s reach their
carrying capacity

Unit
4


Agriculture

How We Starve

Ch.11

Undernourishment:

Malnourishment:

Lack of Calories

< 1.2 x BMR

Lack of Nutrients

Both seem to be caused by energy
-
protein deficiency

Can lead to:

Marasmus

Can lead to:

Kwashiorkor

Deficiency in certain
nutrients
micronutrients seem
to lead to
Kwashiorkor

Unit
4


Agriculture

Ch.11


Global food production has stayed ahead of population growth.
However:


One of six people in developing countries cannot grow or buy
the food they need.


There will need to be a 40% increase in food over the next
20 years

The root cause of hunger and malnutrition is
poverty
.

Unit
4


Agriculture

Ch.11


A 2005 Boston University study found that about 60% of
American adults are overweight and 33% are obese
(totaling 93%).


Americans spend $42 billion per year trying to lose weight.


$24 billion per year is needed to eliminate world hunger.

Overnutrition
:

Under

Healthy

Over
-

Obese

Unit
4


Agriculture

Ch.11


~150 plants have been used as crops


Only 14 are significant for world
-
wide food energy

Wheat


Rice



Maize

Potatoes


Sweet Potatoes

Sugar Cane

Sugar Beets


Beans



Soybeans

Barley



Sorghum


Coconut


Banana


Manioc (yucca/cassava)

Crops:

Unit
4


Agriculture

Ch.11


Traditional agriculture


Low
-
input polyculture

Agroecosystems


Industrialized agriculture


High
-
input monoculture


Plantation agriculture


Crops grown for export


Rangeland


Unplanted grazing land


Pasture


Planted grazing land


Aquaculture


Farming in aquatic
habitats

Can produce higher
yields than high
-
input
monoculture


80% of the world’s food
supply comes from industrial
agriculture


Uses large amounts of fossil
fuel energy, water, fertilizers,
and pesticides

Found in mostly in
tropical areas

“Cash Crops”

(coffee, tobacco, sugar
cane, rubber trees)

Unit
4


Agriculture

Ch.11

1.
Try to stop ecological succession and
keep the
agroecosystem

in an early
successional state


2.
Monoculture: Large areas planted with
a single species


3.
Crops are planted in neat rows


4.
Farming greatly simplifies biological
diversity


5.
Plowing is unlike any natural soil
disturbance


6.
Genetic modification of crops.

How are Agroecosystems different
than natural ecosystems?

Leading to poor soil quality (N, P & K)

Crops have low
genetic variability

Easy for pests and
disease to spread

Leading to greater
soil erosion

Requiring irrigation

Unit
4


Agriculture

Ch.11


After WWII (1950’s


1980’s) programs were enacted aimed at
feeding a booming population

Development of crops with…

higher yields (mostly due to better irrigation techniques)

better disease resistance

better ability to grow under poor conditions


The
Green

Revolution

Since 1978 the amount of irrigated land per person has declined
due to:

Depletion of underground water supplies.

Inefficient irrigation methods.

Salt build
-
up.

Cost of irrigating crops

Unit
4


Agriculture

Ch.11


To increase crop yields, we can mix the genes of similar
types of organisms and mix the genes of different organisms
(
Genetic Engineering)
.

The GENE Revolution

Develop hybrids
faster than nature

Introduce the
“terminator gene”

Transform genes
from one major form
of life to another

Used to:

Strawberry Polyploidy

May create

superhybrids
” that grow
out of control or require
much more fertilizer

wild

Hexaploid

(6n)

Golden Rice

Makes seeds from a crop sterile to:

1.
Prevent genetically modified crops from spreading.


2.
Protect the developer’s economic interest

(Farmers have to keep purchasing seeds)



Has led to undesirable & unforeseen
environmental effects:

Less pesticide needed for crops



WOO HOO!!

But
, every part of the plant including the
edible tissues produce toxin not just the
leaves that the caterpillars eat and
would get sprayed with
pesticide

Unit
4


Agriculture

Ch.12

Soils

High organic content


very fertile

Humus/leaf
-
litter

Mineral
-
rich

Clay

Weathered bedrock

(E)

Undisturbed soils
form
layers/horizons

Unit
4


Agriculture

Ch.12

Soil Texture

Particle size:







Texture

(when wet):

Gritty

Sticky

Slippery

Water/nutrient
Retention:

Erosion/
Sedimentation
threat:

Unit
4


Agriculture

Ch.12

Soils

Clearing natural vegetation

+


Tilling Soil



Erosion of fertile topsoil



Sedimentation of waterways

Annual
Crop

Perennial
grasses

Unit
4


Agriculture

Ch.12

Soils

Methods to help mitigate
soil erosion:


No
-
till or minimum till
seeding


Contour cropping /
terracing


Leaving fields fallow


Rotating crops

Unit
4


Agriculture

Ch.12

Pesticides

Only 10% of pesticide ingredients sprayed on
American crops have been tested by the FDA

Unit
4


Agriculture

Ch.12

There are cultivation, biological, and ecological
alternatives to conventional chemical pesticides.


Cultivate a more diverse crop


Provide homes for the pest enemies.


Implant genetic resistance.


Bring in natural enemies.


Use pheromones to lure pests into traps.


Use hormones to disrupt life cycles.

Integrated Pest Management (IPM)


Uses a combination of alternative
strategies and minimal chemical
pesticides


Goal: to reduce crop damage to
an economically
-
tolerable level

Unit
4


Agriculture

Ch.12

Animal Farming


Overgrazing occurs when the carrying capacity is
exceeded. It can cause severe damage to lands.


Livestock production in developed countries is industrialized:


Feedlots are used to fatten up cattle before slaughter.


Most livestock are fed grain grown on cropland. (40% of
grain grown worldwide)


Systems use a lot of energy and water and produce huge
amounts of animal waste and methane gas.

Unit
4


Agriculture

Ch.12

Desertification

About one
-
third of the world’s land has lost some of its
productivity because of drought and human activities that
reduce or degrade topsoil.

Unit
4


Agriculture

Biodiversity Loss

Soil

Water

Air Pollution

Human Health

Loss and
degradation of
grasslands,
forests, and
wetlands

Erosion

Water waste

Greenhouse gas
emissions from
fossil fuel use

Nitrates in
drinking water

Loss of fertility

Aquifer depletion

Pesticide residues
in drinking water,
food, and air

Salinization

Increased runoff and
flooding from cleared
land

Other air pollutants
from fossil fuel use

Fish kills from
pesticide runoff

Waterlogging

Sediment pollution from
erosion

Greenhouse gas
emissions of
nitrous oxide from
use of inorganic
fertilizers

Contamination of
drinking and
swimming water
with disease
organisms from
livestock wastes

Desertification

Killing wild predators to
protect livestock

Fish kills from pesticide
runoff

Surface and groundwater
pollution from pesticides
and fertilizers

Belching of the
greenhouse gas
methane by cattle

Loss of genetic diversity of
wild crop strains replaced
by monoculture strains

Bacterial
contamination of
meat

Overfertilization of
lakes and rivers from
runoff of fertilizers,
livestock wastes, and
food processing wastes

Pollution from
pesticide sprays

Return to
question # 4

1. What is the predicted
percent decrease in grain
consumption from 1984 to
2015?

2. Using data from the
graph explain why that
decrease from # 1 is
expected.

3. Why was there a huge
increase in grain
consumption from 1950


1984? Explain fully.

4. What are the environmental consequences of that massive
increase in grain production?

5. What needs to be done in order to increase grain production in
the future?

1. What is the predicted
percent decrease in grain
consumption from 1984 to
2015?

350 kg/yr
-

250 kg/yr

=100 kg/yr

100 kg/yr
÷

350 kg/yr x 100


= 28.5%

28.5%

2. Using data from the
graph explain why that
decrease from # 1 is
expected.

Gross grain production is
expected to increase by
about 14% during this time,
while population is
expected to increase by
30%. This gap will cause
the grain that is available
to each person to decrease

3. Why was there a huge
increase in grain
consumption from 1950


1984? Explain fully.

Green Revolution!!


Programs initiated to
increase crop yields


A switch to industrialized,
high
-
input, monoculture


Advances in machinery,
irrigation, chemical
fertilizer, and pesticide
technology

4. What are the
environmental
consequences of that
massive increase in grain
production?

Mention and explain
degradation of


Biodiversity


Soil


Water


Air

Consequences
Chart

5. What needs to be done
in order to increase grain
production in the future?


Convert land used for
livestock to grains for
human consumption


Increase crop yield


Genetically
modified crops


Soil conservation
techniques


Cultivation
techniques