APES 5.3 The Green Revolution

Enduring Understanding:

  • When humans use natural resources, they alter natural systems.

Learning Objective:

  • Describe changes in agricultural practices.

Essential Knowledge:

  • The Green Revolution started a shift to new agricultural strategies and practices in order to increase food production, with both positive and negative results.  Some of these strategies and methods are mechanization, genetically modified organisms (GMOs), fertilization, irrigation, and the use of pesticides.
  • Mechanization of farming can increase profits and efficiency for farms.  It can also increase reliance on fossil fuels.

Characteristics

  • The green revolution is a marked increase in agricultural innovation and the spread of those innovations around the world

    • Norman Borlaug developed new strains of wheat that produced higher yields and were disease resistant
    • In the 1950s, these strains were brought to Mexico and the Philippines to be cultivated there
    • Output increased due to this sharing

  • Movement towards large scale, productive operations

    • Mechanized
    • Monocultures
    • Use artificial fertilizer and pesticides
    • Extensive irrigation used
    • Genetically modified organisms (GMOs) sometimes used

  • Maximized yield per unit area but significant impact on the natural world

Mechanization

  • Machinery does not have the drawbacks of living labor
  • Can be specialized and upgraded
  • Easy to use
  • Efficiency leads to higher profits
  • Fossil fuel use
    • And remember all the factors that go into that: Extraction, combustion, reliance
  • A single farmer cannot manage all of this, farms become reliant upon machines

Monoculture

Pros

  • Easy to plant, maintain, harvest
  • All have the same watering schedule, pests, growing/harvesting times, etc.

Cons

  • Loss of habitat and biodiversity
  • Loss of ancestral varieties
  • Increased possibility of catastrophic event
    • A single disease/pest can come through and kill every crop because they’re all exactly alike

Artificial Fertilizers

  • Haber-Bosch process
    • N2 + 3H2 → 2NH3

Pros

  • Release nutrients over time
  • Can be customized for the plant
  • Mass produced
  • Easily shipped and stored
  • Easily and quickly dispersed
  • No objectionable smell
    • Unlike manure
  • Ensure higher yield due to maximized growth potential

Cons

  • Because of how easily they dissolve, can cause eutrophication after run-off
  • Nitrogen-bearing ions can end up in drinking water
  • Disrupts nitrogen cycle

Artificial Pesticides

Pros

  • Herbicide, insecticide, fungicide
  • Can be customized for the plant
  • Mass produced
  • Easily shipped and stored
  • Easily and quickly dispersed
  • Ensure higher yield due to minimized loss from pest damage

Cons

  • Possible extermination of nontarget species
  • Persistence
    • “Forever chemicals”
  • Possible human health effects
  • Contamination of groundwater
  • Evolution of pesticide-resistant pests
    • Pesticide treadmill
    • The pests become resistant, so we use more pesticide
    • They become resistant to that, so we use even more…
    • So on and so forth

Irrigation

Pros

  • Customizable application
  • Maximized yield by maximizing growth potential

Cons

  • Depletion of freshwater resources
  • Associated environmental effects
    • Waterlogging
    • Salinization

GMOs

Artificial Selection vs. GMOs

  • Artificial selection is human-direction evolution that selects for traits beneficial to humans based on the genetic material available
  • Creating a GMO involves human-directed evolution that selects for traits beneficial to humans, taking advantage of genetic material of normally-incompatible species, creating new traits in the host

Process

  • A gene that has a pest resistant effect from a bacteria, for example, is isolated
  • It is then spliced into the genomic material of a crop
  • The crop gains that pest resistance, despite the gene coming from a completely different organism

Pros

  • Creates crops that can grow on land once unsuitable for agriculture
    • Drought-, heat-, salt-tolerant
  • Crops can be resistant to herbicide
    • Can use stronger herbicides to spray it indiscriminately
    • The herbicide kills the unwanted stuff but the crop lives
  • Crops can produce their own insecticide
    • Reduces use of artificial insecticides

Cons

  • Semiarid and arid lands converted to agriculture already have low nutrient soil
  • Weeds can become herbicide resistant with excess use of herbicide
  • Bt crops may kill nontarget pests
  • Bt crops can lead to insecticide-resistant pests
  • Moral/ethical/economic issues with patented genetic modification