Chapter 12 Soil and Agriculture

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Chapter 12 Soil and Agriculture

• Mr. Manskopf
• Class Web Site
• Http//www.manskopf.com

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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?

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Who Cares About DIRT?
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How is my food choice impacting the environment?
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How come not everyone has enough food?
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About 38 of Earths land surface is used for
agriculture.
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Section 1 Soil

• Explain how soil is formed.
• Describe the different layers (horizons) of soil.
• List four characteristics used to classify soil.

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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

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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 organismsmany
  microscopic decomposers

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Why is soil important

• Renewable resourceSLOW
• Depends upon climate (1cm in 15yrs.)
• Basis of life
• Filters water
• Water storage
• Habitat

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Simplified Soil Food Web
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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

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Weathering of PARENT MATERIAL (ROCK)
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Decomposition
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Leaf Litter
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Different Biomes Different Parent Material,
Climate, Organic Matter Different Soil
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Soil Horizons

• Soil horizons are distinct layers of soil.
• A cross-section of soil horizons is a soil
  profile.
• A Most Critical

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Did You Know? In general, organic matter is
concentrated in the O and A horizons, making them
the most critical for agriculture.
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Is All DIRT The Same?
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Soil Characteristics

• Soil groups are further classified according to
  properties such as color, structure, pH, and
  texture.
• Soil texture is based on particle size.

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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)
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Section 1 Review

• Explain how soil is formed.
• Describe the different layers (horizons) of soil.
• List four characteristics used to classify soil.

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Section 1 Quiz

• 1) After a catastrophe, soil formation is the
  first step in
• A. primary succession.
• B. secondary succession.
• C. a climax community.

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2) Most of the nutrients in soil come fromA.
chemical weathering. B. mechanical
weathering. C. erosion.
D. decomposition.
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3) A farmer interested in raising healthy crops
should look for aA. 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.
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4) An example of a soil parent material isA.
humus. B. volcanic rock.
C. leaf litter. D. topsoil.
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5) As a farmer, you would be most concerned with
the quality of the soil in theA. O horizon.
B. A horizon. C. E
horizon. D. R horizon.
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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 pastures
overall fertility?A. color B. smell
C. structure D. pH E. Taste
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7) Short Answer If you were to travel to the
desert in Arizona, you might find Horizon Layer O
and A missing. Why?
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8) Short Answer What determines how quickly
Horizon O and A form?
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Some estimates predict that 50 million people
could be displaced in the next 10 years due to
desertification, a form of soil degradation.
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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?

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Causes of Soil Erosion

• Wind
• Water 1
• People

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Soil Erosion

• Often occurs faster than soil is formed,
  depleting fertile topsoil
• Crops, trees, and other plant communities protect
  soil from erosion.

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Did You Know? More than 19 billion hectares (47
billion acres) of the worlds croplands suffer
from erosion and other forms of soil degradation
resulting from human activities.
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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)

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What time of year do you think most farm fields
in U.S. are vulnerable to erosion?
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On Ag. land in U.S. today, soil is eroding 16
times faster than it is created
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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

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Tillage vs. Conservation Tillage
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Contour and Strip Cropping
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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.

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Forestry Practices

• Forestry practices, such as clear-cutting, can
  increase erosion.
• Today, practices that reduce soil erosion, such
  as selective logging, are increasingly common.

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Soil Pollution

• Too much, or carelessly timed irrigation can
  waterlog crops and lead to salinizationa buildup
  of salts in upper soil horizons.
• Toxic pesticides can remain in soil for a long
  time, eventually filtering to groundwater.

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Desertification
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Soil Salinization
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Soil Pollution
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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?

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Humans have been practicing agriculture for about
10,000 years.
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What is that?
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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.

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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?

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The Beginnings of Agriculture
People were hunter-gatherers through most of
human history, until agriculture developed about
10,000 years ago.
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Why 10,000 years ago?
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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.

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Types of Agriculture

• Traditional Agriculture

Industrial Agriculture
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The Green Revolution

• Introduced new technology, crop varieties, and
  farming practices to the developing world in the
  mid- to 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

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Green Revolution

• Costs
• Led to a 7000 increase in energy used by
  agriculture
• Worsened erosion, salinization, desertification,
  eutrophication, and pollution

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Pests and Weed Control (Farmers Enemies)

• Chemical pesticides Effective and cheap, but can
  lead to resistance

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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.
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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

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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?