Bio102-Chap7Notes - Agriculture: Resources & Impacts...

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Agriculture: – Themes 0. Agriculture: Background 0. Major food resources 0. Agricultural methods 0. World food supply 0. Environmental Impacts (Huge!!) 1. Damage from energy, water, pesticide use 1. Land degradation / Soil loss 1. Overgrazing/Desertification 0. Solving Problems 2. Green revolution? 2. Sustainable agriculture 1. Background a. Major Food Sources 3 crops provide majority of world’s nutrients: 0. Wheat, Corn, Rice —> > 50% of world’s calories 1. Regional differences: Potatoes, barley, oats —> cool, moist climates Cassava, sweet potatoes, sorghum —> tropical climates Meat and Milk distribution highly inequitable 60% of production occurs in LDCs 90% of U.S. grain feeds livestock! o 16 kg of grain produce about 1 kg of edible beef o Eating grain directly —> 21x more calories and 8x more protein than eating beef Seafood is an important protein source Cannot solve world hunger problem ! 0. Between 1970-1990, world fishing fleet doubled annual harvest increased slightly (is it sustainable??) Since 1980s, 13 of 17 major fisheries have declined dramatically (commercially unviable?) 1. Catching $70 billion in fish costs $124 billion 1/4 of catch is lost (by-catch) b. Agricultural Methods (Approaches) 0. History of agriculture Cultivation of different crops began ~ 10,000
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years ago in at least 3 different regions 0. Wheat (Fertile crescent) 1. Corn (Mexico) 2. Rice (S. China) 0. World Agriculture Today- a) Resource-based agriculture: 0. Subsistence Agriculture (50% of all croplands) Two main kinds: Nomadic herding (subtropical, dry) Shifting cultivation (tropical forests) 1. 1 farmer feeds family 2. High land, low energy, low capital 3. Intensive Agriculture (25% of all croplands) 4. Agriculture in China, India, etc. (esp. Rice) 5. 1 farmer feeds several 6. High labor, low energy, low capital b) Demand (Industrialized) Agriculture (25% of all croplands) 7. High energy , high capital, low labor inputs 8. Goal: production per unit of land area fertilizer + pesticides + irrigation mechanization (10 units fossil fuel energy = 1 unit food energy) crop breeding —> high yielding species = “Green Revolution” —> Sustainable ? 9. 1950 - 1995: 2x crop production in U. S. 10. Required: 4x fossil fuels 10x fertilizers 30x pesticides 3) World Food Supply 2. World supply has improved over past 2 centuries 1950 - 2.5 billion people —> 2,000 calories/person 2001 - 6.0 billion people —> >2,500 calories/person 3. Many regional shortages: Sub-Saharan Africa has had several famines 0. Widespread starvation, social upheaval, economic chaos
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Bio102-Chap7Notes - Agriculture: Resources & Impacts...

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