Food and Agriculture

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					Food and Agriculture


     Crops and Soil
      Chapter 15
      Section Two
Agriculture: Modern vs. Traditional
•   Machinery               • Manual labor
•   Synthetic fertilizers   • Organic fertilizers
•   Sprinkler systems       • Weeds removed by
•   Drip irrigation           hand
•   Pest management         • Relied on rainfall
                            • Ditch irrigation
                              systems
Fertile Soil: The Living Earth
• Supports the growth of healthy plants
• Topsoil – surface layer, rich in organic
  matter
• Subsoil – poorer in quality than topsoil
• Billions of organisms per hectare:
  bacteria, insects, arthropods,
  earthworms, algae
Soil structure
Soil Erosion and Degradation
• Erosion – wearing away of rock and soil
  by wind and water
• Degradation – human activity or natural
  processes damage the land so it can no
  longer support the local ecosystem
• Desertification – land becomes more
  desertlike because of human activities
Soil Conservation
• Many ways to prevent downhill erosion
• Contour plowing – follow natural land
  contours
• Terracing – many small level fields
• No-till farming – harvest and plant next
  crop without plowing, reduces erosion
  to 1/10 of traditional methods
Enriching the Soil
• Traditionally – organic material such as
  manure & leaves which adds nutrients
• Modern methods include inorganic
  matter which can lead to runoff issues
• Best method – combination of both;
  compost, partly decomposed organic
  matter, combined with inorganic
  fertilizers
Salinization
• Accumulation of salts in the soil
• California and Arizona – irrigation water
  is saltier than rainwater and when it
  evaporates, salt is left behind
• Eventually, plants will not grow
Crops and Soil


  Chapter 15
  Section Two
   Part Two
Pest Control & Pesticides
• In NA, insects 13% of all crops
• Worldwide, pests destroy 33% of crops
• Pest – any organism that is where it
  isn’t wanted or in large enough
  numbers to cause economic damage
• Pesticides – chemicals used to kill
  weeds, insects & other crop pests
• Pesticides can kill/harm good plants,
  insects, wildlife, and people
  – Causes cancer in farmers, manufacturing
    plant workers,
• Resistance – ability to survive exposure
  to certain pesticide
• Persistence – does not break down
  easily or quickly in the environment,
  build up in soil or water
• Some have been banned (DDT – made
  in US and sold overseas)
Biological Pest Control
• Use of living organisms to control pests
• Pathogens – cause disease in pests
• Some plants have natural defenses and
  come make defensive chemicals
• Disrupt pest breeding cycles
Integrated Pest Management – don’t
eliminate the pest, just reduce the
amount of damage
Engineering and Sustainability
• Genetic engineering – modify genetic
  material so plant can resist/kill pests
  – Bt corn
• Sustainable agriculture – conserve
  resources and keep land productive
• Low-input farming – plant pest resistant
  crops that minimize use of water,
  energy, pesticides & fertilizer
Genetically Modified Crops

				
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