Chapter 12
Soil and Agriculture
Mr. Manskopf
Class Web Site
Http://www.manskopf.com
Essential Questions Covered
• What are the components of the soil?
• How is soil formed?
• What are some of the effects of soil erosion on the
land?
• Describe the impact of human activities on the
land.
• How do recycling and composting programs affect
the soil?
• What impact do pesticides have on the soil?
• What affect do fertilizers have on the nitrogen
cycle?
Who Cares About DIRT?
How is my food choice impacting the
environment?
How come not everyone has enough
food?
About 38% of Earth’s land
surface is used for
agriculture.
Section 1 Soil
• Explain how soil is formed.
• Describe the different layers
(horizons) of soil.
• List four characteristics used to
classify soil.
What is soil made of?
• Soil is made up of
minerals, organic
matter, air, and water.
• Soil composition is
influenced by climate,
organisms, landforms,
parent material, and
time
Soil Composition
• Soil is a thin layer
over most land that
is a complex mix of
rock, nutrients,
decaying matter,
water, air and
billions of
organisms…many
microscopic
decomposers
Why is soil important?
• Renewable
resource…SLOW
• Depends upon
climate (1cm in
15yrs.)
• Basis of life
• Filters water
• Water storage
• Habitat
Simplified Soil Food Web
Soil Formation
• Weathering: Physical and
chemical breaking of rocks and
minerals into smaller pieces
• Erosion and deposition: Pick-up,
transport, and
drop-off of material from one
place to another
• Decomposition: Breakdown of
waste, organisms, and organic
material into simple molecules
Weathering of PARENT MATERIAL (ROCK)
Soil Horizons
• Soil horizons are
distinct layers of
soil.
• A cross-section
of soil horizons is
a
soil profile.
• “A” Most Critical
Did You
Know? In
general,
organic matter
is
concentrated
in the O and A
horizons,
making them
the most
critical for
agriculture
.
Soil Characteristics
• Soil groups are
further classified
according to
properties such as
color, structure,
pH, and texture.
• Soil texture is based
on particle size.
Topsoil Color a Great Quick Indicator
Dark, loamy,
neutral pH are
some of best
soils for farming
Dark color often
means lots of
decayed material
(nutrients)
Section 1 Review
• Explain how soil is formed.
• Describe the different layers
(horizons) of soil.
• List four characteristics used to
classify soil.
Section 1 Quiz
1) After a catastrophe, soil
formation is the first step in
• A. primary succession.
• B. secondary succession.
• C. a climax community.
2) Most of the nutrients in soil
come from
A. chemical weathering.
B. mechanical weathering.
C. erosion.
D. decomposition.
3) A farmer interested in raising healthy
crops should look for a
A. heavy clay soil with a high pH and a dark
color.
B. loamy soil with a low pH and a light
color.
C. loamy, clumpy soil with a neutral pH and
a dark color.
D. sandy soil with a high pH, no clumps,
and a light color.
4) An example of a soil parent
material is
A. humus.
B. volcanic rock.
C. leaf litter.
D. topsoil.
5) As a farmer, you would be most
concerned with the quality of the
soil in the
A. O horizon.
B. A horizon.
C. E horizon.
D. R horizon.
6) A rancher interested in the quality of
the soil in her pasture might use which
aspect of soil as a quick indicator of the
pasture’s overall fertility?
A. color
B. smell
C. structure
D. pH
E. Taste
7) Short Answer: If
you were to travel to
the desert in Arizona,
you might find
Horizon Layer O and
A missing. Why?
8) Short Answer: What determines
how quickly Horizon O and A form?
Some estimates predict that 50 million people
could be displaced in the next 10 years due
to desertification, a form of soil degradation.
Section 2 Soil Degradation and
Conservation
• What causes soil erosion?
• How serious of a problem is it?
• What are ways that farmers,
ranchers and forestry lead to soil
erosion?
Causes of Soil Erosion
Wind
Water #1
People
Soil Erosion
• Often occurs faster
than soil is formed,
depleting fertile
topsoil
• Crops, trees, and
other plant
communities
protect soil from
erosion.
Did You Know? More
than 19 billion hectares
(47 billion acres) of the
world’s croplands suffer
from erosion and other
forms of soil degradation
resulting from human
activities.
Impacts of Soil Erosion
• Loss of soil fertility
• Sediment runoff causes
problems in surface water
(pollution, clog ditches,
boat channels, reservoirs)
• #1 source of U.S. water
pollution
• Renewable only on LONG
timeframes (200-1,000yrs.
for 1 inch)
What time of year do you think most farm
fields in U.S. are vulnerable to erosion?
On Ag. land in U.S. today, soil is eroding 16
times faster than it is created
Areas of serious concern
Areas of some concern
Stable or nonvegetative areas
Farming Practices That
Reduce Erosion
• Intercropping: Different crops
mixed together
• Crop rotation: Crops are
alternated.
• Shelterbelts: Tall plants
block wind.
• Conservation tillage: Soil
turnover is reduced.
• Terracing: Steep slopes
turned into “steps”
Tillage vs. Conservation Tillage
Contour and Strip Cropping
Ranching Practices
• Ranching is the raising and
grazing of livestock.
• Overgrazing causes and
worsens many soil
problems.
• Range managers
encourage grazing limits
and enforce them on
publicly owned land.
Forestry Practices
• Forestry practices,
such as clear-cutting,
can increase erosion.
• Today, practices that
reduce soil erosion,
such as selective
logging, are
increasingly common.
Soil Pollution
• Too much, or carelessly
timed irrigation can
Evaporation
Evaporation
Transpiration
waterlog crops and lead to
salinization—a buildup of
salts in upper soil horizons.
• Toxic pesticides can remain
in soil for a long time,
eventually filtering to
groundwater.
Waterlogging
Less permea
clay layer
Desertification
Soil Salinization
Soil Pollution
Section 2 Review
• What causes soil erosion?
• How serious of a problem is it?
• What are ways that farmers,
ranchers and forestry lead to soil
erosion?
Humans have been
practicing agriculture
for about 10,000
years.
What is that?
Aldo Leopold
There are two spiritual dangers
in not owning a farm. One is the
danger of supposing that
breakfast comes from the
grocery store, and the other
that heat from the furnace.
Section 3 Agriculture
• Describe the history of farming.
• Analyze the costs and benefits of the “Green
Revolution”
• What are some ways farmers control weeds
and pests?
• Why are pollinators important to farmers?
What are some of the ecological and
economic services that croplands
provide? (what good are farms?)
The Beginnings of Agriculture
People were hunter-gatherers through most of
human history, until agriculture developed
about 10,000 years ago.
Why 10,000 years ago?
Agriculture History
• In early agriculture,
people began planting
seeds from plants they
liked most
• Agriculture and
livestock provided a
stable food supply,
which allowed the
development of
modern civilization.
Types of Agriculture
• Traditional Agriculture
Industrial
Agriculture
The Green Revolution
• Introduced new technology, crop
varieties, and farming practices to
the developing world in the midto late 1900s
Benefits:
• Increased crop yields and saved
millions of people from
starvation in India and Pakistan
• Prevented some deforestation
and habitat loss by increasing
yields on cultivated land
Green Revolution
Costs:
• Led to a 7000% increase in energy used by
agriculture
• Worsened erosion, salinization, desertification,
eutrophication, and pollution
Pests and Weed Control (Farmers
Enemies)
• Chemical pesticides: Effective and cheap,
but can lead to resistance
Pests and Weed Control
•Biological pest control:
Permanent solution,
but can harm nontarget
organisms
•Integrated pest
management:
Increasingly popular
solution, combines
chemical and biological
pest-control methods
Cactus moth larvae are
used to control prickly pear
cactus, but also threaten
many rare, native cacti
around the world.
Pollinators
• Agriculture relies on
pollinators, such as
insects.
• Native and
domesticated pollinator
populations have
declined due to
pesticide use, parasites,
and other as-of-yet
unknown causes
Section 3 Review
• Describe the history of farming.
• Analyze the costs and benefits of the
“Green Revolution”
• What are some ways farmers control
weeds and pests?
• Why are pollinators important to
farmers?
• Each year, Earth gains 75 million
people and loses 5–7 million
hectares of productive cropland.
Section 4: Food Production
• How is our food produced and what
impact does that food production have
on our environment?
• What are GM foods?
• What does sustainable food production
look like?
Large amounts of
macronutrients (protein,
carbs, fats)
Small amounts of
micronutrients (A, C, E,
iron, iodine, calcium)
• Chronic under nutrition:
disease increase, stunted
growth etc.
• Malnutrition: can not get
enough protein mainly
eating corn, rice, wheat
• Huge childhood problem
Human Needs
Malnutrition
UN Estimates:
• 5.5 million each year die
prematurely due to
effects of under
nutrition.
• Each day 15,100 people -- 80% of which are
children
• In U.S. estimates are 11
million do not have
access to enough food
Food intake exceeds
energy use and causes Over nutrition
body fat
• Too many calories not
enough exercise
• Lower life expectancy,
heart disease, lower
productivity and quality
of life
• In developed countries
it is 2nd leading
preventable cause of
death after smoking
Food Security
Since 1960, our ability to
produce food has grown
faster than the human
population, but 1 billion
people are hungry
worldwide.
Malnutrition and
undernourishment are
most common in the
developing world.
Arable Land
• Land suitable for
farming
• Running out
• Loosing soil
Genetically Modified Organisms
Organisms that have had
their DNA modified
Commonly engineered traits
include rapid growth, pest
resistance, and frost
tolerance.
In the United States,
85% of corn and 90% of
soybean, cotton, and canola
crops come from GM strains.
Risks and Benefits of GM Crops
Potential for
“superpests” that are
resistant to pestresistant crops
Contamination of
non-GM plants
Benefits of GM Crops
•Benefits:
•Insect-resistant
crops reduce the
need for
insecticides.
•Herbicide-resistant
crops encourage
tillage
conservation.
Industrial Food Production:
Feedlots
Alternative to open
grazing in which
energy-rich food is
delivered to a
concentrated group of
livestock or poultry
Benefits and Cost of Feedlots (Factory
Farms)
Benefits: Reduces soil
degradation and
fertilizer use
Costs: Requires
antibiotic use;
potential for water
contamination and
animal stress
What is this?
Industrial Food Production:
Aquaculture
Fish farming in a
controlled
environment
Benefits and Costs of Aquaculture
Benefits: Can be
sustainable; reduces bycatch; reduces fossil fuel
use
Costs: More difficult to
control spread of diseases;
produces a lot of waste;
potential for farm-raised
animals to escape into wild
Sustainable Agriculture
• Does not deplete soil
faster than it forms
• Does not reduce the
amount or quality of
soil, water, and
genetic diversity
essential to long-term
crop and livestock
production
Sustainable Agriculture
• Organic agriculture is
sustainable agriculture
that does not use
synthetic chemicals.
• Local, small-scale
agriculture reduces
the use of fossil fuels
and chemicals used for
transportation and
storage.
U.S. Food travels avg. of 1,500
miles from farm to fork in U.S.
New Jersey Peach Farm: What are the
advantages and disadvantages of eating locally grown
food?
Section 4 Review
• How is our food produced and what
impact does that food production have
on our environment?
• What are GM foods?
• What does sustainable food production
look like?
Section 4 Quiz
1) Agriculture most likely began
• A. 10,000 years ago in the Middle
East.
• B. 200,000 years ago in Africa.
• C. 15,000 years ago in China.
D. 150,000 years ago in Egypt.
2) Genetic engineering relies on placing
a gene that codes for a desired trait
into the __________ of a different
organism from the organism where the
gene was originally harvested.
A. protein
B. amino acid
C. helix
D. genome
3) Your friend tells you she’s decided not
to use pesticides or synthetic chemicals on
her farm; instead she’ll rely on composting
and biological pest control. She is
practicing
A. industrial agriculture.
B. monoculture.
C. organic agriculture.
D. sustainable agriculture.
4) Sustainable agriculture is
important because while human
population continues to grow,
which of the following will not?
A. animal population
B. arable land
C. food production
D. GM crops
5) What event enabled the evolution of
agriculture?
A. a warming climate due to volcanic
eruptions in Indonesia
B. a sudden growth in human population
C. a decrease in natural prey species,
such as large hooved mammals
D. a warming climate, which ended an
ice age
6) A large area of cropland seeded
with one crop is a(n)
A. monoculture.
B. polyculture.
C. organic practice.
D. traditional farming technique.
7) A farmer has an infestation of aphids
and greenflies. He introduces ladybugs,
which prey on aphids, and uses a limited
dose of a pesticide to deal with the flies.
The farmer’s approach to insect pests is
A. chemical control.
B. biological control.
C. integrated pest management.
D. organic pest management.
8) You would expect to find most
farmers who use GM crops living in
A. relatively poor, undeveloped
countries.
B. countries with strong environmental
protection laws.
C. countries with weak environmental
laws.
D. relatively wealthy, developed
countries.
9) The average food item in the United
States travels 2400 km to reach the
buyer. One alternative to this energyinefficient practice is
A. treating the food with preservative
chemicals.
B. buying locally produced food.
C. buying organic food.
D. buying GM food.
10) GM foods are engineered to resist
herbicides so that
A. humans won’t be put at health risk
from pesticides.
B. insect pests will avoid the crops.
C. the crops will grow more efficiently.
D. farmers can use heavier doses of
pesticides for weeds without killing the
crop plants.
11) In the Chart, which is the most
efficient source of animal protein?
12) Chart B illustrates energy transfer and
trophic structure in a natural ecosystem. If this
was an agriculture ecosystem, where would
humans be located?