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Agriculture notes

Agriculture notes. Brief History. Fossil evidence indicates that modern humans evolved in East Africa about 200,000 years ago During most of there existence they survived by hunting and gathering Agriculture started about 10,000 years ago

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Agriculture notes

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  1. Agriculture notes

  2. Brief History • Fossil evidence indicates that modern humans evolved in East Africa about 200,000 years ago • During most of there existence they survived by hunting and gathering • Agriculture started about 10,000 years ago • The development of agriculture gave rise to civilization. • http://www.history.com/shows/mankind-the-story-of-all-of-us/videos/mankind-the-story-of-all-of-us-farming

  3. Subsistence Farming • Early agriculture was mostly subsistence farming • Subsistence farming – when the family produces just enough food to support the family unit (without excess intended for sale or trade) • Although this early farming method could deplete soil, it did not involved many of the environmentally detrimental techniques that are characteristic of modern farming.

  4. Manipulating the environment • Agriculture by its very nature requires humans to manipulate the natural environment • Examples -plowing, tilling land -fertilizers -pesticides -monocultures -artificial selection -genetically modified organisms

  5. Pests • Pest – a troublesome, destructive, or annoying organism (this definition is from a human’s perspective of course) • Pests can cause many problems -can compete with humans for food (destroy crops) -can carry disease (example – malaria and yellow fever) -can have negative effects on native wildlife/environment -can cause damage to residential and commercial property

  6. Pests - examples • Insects (can be killed by insecticides) • Fungi (can be killed by fungicides) • Mammals (can be killed by rodenticides and other poisons) • Nematodes (can be killed by nematicides) • Birds (can be killed by avicides) • Weeds (can be killed by herbicides) • Any organism that “interferes” with human activities can be considered a pest

  7. Pests – a man-made problem • Introduced species – often become pests • Monocultures (growing a single kind of plant over a large area) encourages pest development -provide abundant food supply -often eliminate/reduce natural predators • Pesticides – often make the pest problem worst by making the targeted pest stronger and destroying natural predators

  8. The evolution of pesticides • Early pesticides – natural minerals or chemicals, were expensive and had limited success at controlling pests • Chlorinated hydrocarbons (including DDT) -discovered during WWI when insects were used to test chemicals (nerve gas) -became the most important group of insecticides

  9. Chlorinated hydrocarbons • Cheap and easy to use • Killed many different kinds of insects • Continued to kill insects long after they were applied (persistent) • DDT was the first widely used chlorinated hydrocarbon • DDT was banned in the U.S. in 1972 due to its adverse effects on the environment http://www.cbsnews.com/news/the-legacy-of-silent-spring/

  10. Pesticides -types • Persistent vs biodegradable – persistent take a long time to break down in the environment while biodegradable pesticides break down more easily • Broad-spectrum vs. selective – broad-spectrum kill many different organisms including the target pest while selective kill the target organism *In North America only 1 out 8 insects is considered a pest!

  11. Pesticides Pros and Cons • Pro – saved millions of lives and billions of dollars worth of crops, protect humans from disease and hunger • Con – can affect the natural ecosystem (often times in ways that we can not predict), can cause health problems, often make pests stronger (resistant)

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