Agriculture and Pest Management

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Chapter 15

• Agriculture and Pest Management
• Agriculture Methods
• Slash and Burn Agriculture.
• Small areas - usually in tropics
• Burning returns nutrients to soil
• polyculture practiced plant many different
  types of plants
• Land recovers - forest re-invades
• Labor Intensive Agriculture
• Occurs under three conditions
• 1. When topography wont allow mechanization
• 2. When crop wont allow it
• 3. Where cost is prohibitive and labor cheap

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Chapter 15

• Mechanized Agriculture
• Typical of North America, Europe and former
  Soviet Union
• Requires large tracts of land
• Special varieties of plants that can be harvested
  by mechanical means (hybrids, G.E. species)
• monoculture planting only one species of plants
  on large areas
• Can cause soil erosion and depletion of soil
  nutrients
• Cheap fuel - energy from fossil fuels replaces
  labor
• Has significantly increased food production

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Chapter 15

• Energy Versus Labor
• Mechanized agriculture substitutes energy from
  petroleum for human labor
• 1913 - took 135 hours of labor to produce 2,500
  kilograms of corn
• 1980 - took 15 hours to produce 3500 kilograms of
  corn
• Energy from petroleum is used for
• Tilling, planting harvesting, pumping water,
• To produce fertilizers, pesticides - herbicides,
  fungicides and insecticides
• Changes in the cost or availability of fuel will
  impact on the worlds ability to feed itself!!!!
• Broad implication of US dependence on foreign oil

4
Chapter 15

• Impacts of fertilizers
• 25 of the worlds crop yields is attributed to
  the use of fertilizers - no fertilizers- 25
  decrease in food
• oil costs - poverty- hunger - fertilizer paradox
• Macro nutrients nitrogen (N), phosphorus (P),
  potassium(K) also C,H,O but
• Micronutrient copper zinc, iron, magnesium,
  manganese, boron, etc
• Why do we have to fertilize? Where do the Macro
  nutrients and micronutrients go?

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Chapter 15

• Inorganic fertilizers do not replace organic
  matter !
• Why is organic matter important?
• Humus
• prevents compaction, makes poor spaces
• lowers pH
• serves as food for bacteria and earthworms
• holds moisture
• holds nutrients and provides slow release of
  them, less runoff of pollutants 
• Total dependency on inorganic fertilizers causes
  adverse changes in soil properties.

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Chapter 15

• Pesticides
• Pesticide any chemical used to kill or control
  the populations of unwanted fungi, animals, or
  plants (pests). Weeds unwanted plants
• Herbicide kills plants
• Insecticide kills insects
• fungicide kills fungi
• rodenticide kills mice and rats
• Target organisms pests you desire to kill
• nontarget organisms other organisms killed by a
  pesticide in addition to targeted pest including
  many beneficial organisms

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Chapter 15

• Insecticides
• Natural insecticides
• Nicotine
• Pyrethrum - chrysanthemums
• Rotenone
• Synthetic organic insecticides
• 1867 - Paris green - acetate and arsenide
• 1942 - DDT - dichlorodiphenyltrichloroethne
• DDT saved 5 million lives in first ten years of
  uses. BUT insects became tolerant and DDT
  biomagnified !!!!

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Chapter 15

• Three Types of Synthetic Insecticides
• 1. Chlorinated hydrocarbons
• Examples DDT, aldrin, dieldrin, toxaphene,
  chlordane, mirex, kepone 
• Mode of action thought to be a neurotoxin, but
  mode(s) of action is / are not fully understood
•  
• Very persistent- half life 10-15 years
•  
• Banned in U.S. but still used in developing
  countriesproblem?

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Chapter 15

• 2. Organophosphate
• Examples Chlorpyrifos (Dursban)
• Diazinon (Spectracide),
  Malathion
•  Mode of action - cholinesterase inhibitor
•  Short half lives, but more toxic to humans and
  require more frequent applications
• 3. Carbamates
• Examples carbaryl (Sevin)
•  Mode of action - cholinesterase poison
• Half life - short - hours/days

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Chapter 15

• Problems With Pesticide Use
• 1. Persistence - hard pesticides
• Global transport - found all over the world
• Bioconcentration, bioaccumulation,
  biomagnification (amplification)
• 2. Insects build up resistance
•  
• 3. Impacts on non-target beneficial organisms
•  
• 4. Short term and long term health problems of
  farm workers

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Chapter 15

• Reasons Pesticides Are Widely Used
•  
• 1. Use of Pesticides has increased about of food
  that can be grown worldwide
•  
• 2. Economics - cost of pesticides is less than
  the increased value of crops produced
•  
• 3. Needed to control disease organisms

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Chapter 15

• Organic Farming
•  
• Prior to availability of fertilizers and
  pesticides all farming was organic
•  
• Organic farming is use of animal manure, crop
  rotation, mixture of crops, manual labor or
  biocontrol to kill pests
•  
• Organically grown vegetables, grains and meat
  are gaining in popularity because of health
  concerns over use of pesticides and because of
  nutrition concerns

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Chapter 15

• Integrated Pest Management
•  
• Integrated Pest Management use of a variety of
  methods to control pests rather relying on use of
  pesticides alone - Integrated use of chemical,
  physical and biological methods of controlling
  pests
•  
• Examples Use of sex attractants (pheromones),
  male sterilization, release of predators and
  parasites, pest resistant crops, use of natural
  pesticides, modification of farming techniques