ag1 - AgricultureandSoil Lecture7 TheScopeofAgriculture

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Agriculture and Soil Lecture 7
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The Scope of Agriculture Agriculture is the basis of civilization Developments associated with Agriculture § Transition from food gathering to food  production § Landform modification § More food from given area of land § Food surplus – buffer against hardship § Trading surplus § Improved health/longevity (?)
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The Scope of Agriculture Most extensive human use of the planet – 18% of the world’s land area currently farmed 22% is grazed by livestock 4 - 5% is urbanized 30% of the natural productivity of Earth’s  ecosystems  is captured or changed by  agriculture
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Croplands and  pastures now rival  forest for area of  land surface  occupied – 40%
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Native vegetation cleared for cultivation loss of habitat soil exposure hydrologic changes Increasing food supply leads to increased  population and more agriculture – impact spiral Intensifying agriculture can intensify its effects Soil loss and soil degradation Consequences of Agriculture
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Soil is unbelievably complex – Mineral particles – from parent material Organic remnants Gaps filled with air or water –  dissolved substances A whole lot of organisms The action of living organisms is essential for soils to fully develop -  worms, plants, bacteria, fungi, yeast, etc. st Dirt
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Development of Topsoil
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Human action can affect all of these variables, either  positively or negatively
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Soil Formation and Primary  Succession
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Parent Material  Beneficial: Adding structure and nutrients to soil Harmful: Nutrient leaching Topography (Land-surface relief) Beneficial: Terracing; reducing slope angles Harmful: Slope oversteepening; mass-wasting; erosion Humans Can Affect Soil Formation Factors
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ag1 - AgricultureandSoil Lecture7 TheScopeofAgriculture

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