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Crops and Soil Chapter 15 Section Two
Food and Agriculture Crops and Soil Chapter 15 Section Two
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Agriculture: Modern vs. Traditional
Machinery Synthetic fertilizers Sprinkler systems Drip irrigation Pest management Manual labor Organic fertilizers Weeds removed by hand Relied on rainfall Ditch irrigation systems
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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
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Soil structure
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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
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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
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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
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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
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Chapter 15 Section Two Part Two
Crops and Soil Chapter 15 Section Two Part Two
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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
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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)
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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
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Integrated Pest Management – don’t eliminate the pest, just reduce the amount of damage
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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
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Genetically Modified Crops
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