15-2 Crops and Soil

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15-2 Crops and Soil
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• Traditional Methods
• Animal or human power
• Organic fertilizers and mulch
• Flowing water through ditches
• Weeds removed by hand or machine

• Modern Methods
• Machine power with fossil fuels
• Synthetic chemical fertilizers
• Synthetic pesticides and herbicides used to kill
  pests
• Variety of irrigation methods

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Erosion

• Two main causes wind or water
• When vegetation is removed by plowing or cutting
  the roots that anchor the soil can no longer do
  so.

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Desertification

• Land in arid or semi-arid regions converting from
  grassland to desert
• Worldwide grasslands are farmed most.
• When they are overgrazed or crops are not rotated
  a type conversion results

Sahel - Africa
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Salinization

• Accumulation of salts problem in arid
  environments
• Can eventually result in unusable land
• Ex Westlands water district

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Westlands salinization
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Conserving and enriching the Soil

• Management techniques include
• Contour plowing
• Row crops
• Drip irrigation
• No-till farming

• Compost and inorganic fertilizers

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Section 15-2 Part II
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Pests, Pesticides and Pest Control

• Any organism that occurs where it is not wanted
  or that occurs in large enough numbers to cause
  economic damage
• Plants, fungi, microorganisms, insects etc..

Gypsy moth Eastern Forests
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• Wild plants often have natural resistance to pest
  species
• One reason crops are susceptible is that they are
  not genetically diverse and are grown in
  monocultures

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Pesticides

• Used to kill insects, weeds and other pests
• Some are synthetic others are derived from
  natural chemicals (nicotine)

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Pesticide resistance

• Over 500 species of insects have evolved
  resistance to pesticides since 1940
• Many plants are now resistant to herbicides

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Human Health Concerns

• Cancer risk
• Biomagnification (DDT)
• Hormone mimics (chlordane)

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Biological Pest Control

• Using living organisms to control pests
• BT used to control caterpillars (bacteria that
  eats them from the inside)
• VNT uses natural barriers and chemical defenses
• Biodegradable toxins from plants

Chrysanthemum
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Integrated Pest Management

• Includes a mix of sustainable approaches

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Sustainable Agriculture

• Keeps land productive indefinitely
• Minimizes use of energy, pesticides, water and
  fertilizer
• Make use of natural controls and crop rotation