GEOstudyguide - Chapter 7 1960-60 of the world...

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Chapter 7 1960-60% of the world undernourished Today-15% 2030-Enough food available for everyone Today-Surplus yet 840 million hungry - Africa, Latin America, SE Asia Malnourishment-lack of specific dietary components Most common: Iron deficiency (Good sources of iron: red meat, eggs, legumes, vegetables) Iodine deficiencies affect ~740 M people (SE Asia) ~1M Child deaths/year due to lack of essential vitamins/minerals ~350,000 children go blind due to Vitamin A deficiency In America: Over 64% of adults are overweight ~1/3 are obese ~400,000 related deaths 1st time in history: More overweight people (~1B) in the world than underweight Majority of world's food: Wheat, Rice, Corn Potatoes, Barley, Oats Rye-Cool moist climates Cassava, sweet potatoes, other roots-warm wet climates Protein-rich foods prized around the world 660M tons of cereal to feed livestock Since 1989, 13 of 17 major fisheries have become commercially unsustainable Only 10% of all large fish left Industrial fisheries need only 10-15 years to drop any new fishing community to 10% level 20,000 different soil types in US alone Soil horizons: layers of soil O Horizon - Organic Layer: leaf litter, partially decomposed A Horizon - Topsoil: Mineral particles mixed with organic material E Horizon- Leached: Depleted of soluble nutrients B Horizon- Subsoil: Often dense texture from accumulating nutrients C Horizon- Parent Material: Weathered rock fragments with little organic material
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Approx 11% of earth's land area is devoted to agricultural production In developed countries, ~95% of agricultural growth stems from pesticides/fertilizer usage Less land cultivated in US than 100 yrs ago ~3M ha cropland lost to erosion, ~4M ha transformed to deserts, ~8M ha converted for non-ag uses Land is considered degraded when: Soil is improvished or eroded Runoff is contaminate Biodiversity is diminished Erosion - redistribution of the products of geologic weathering, part of both soil formation and soil loss Reduces crop production by 1% each year Sheet erosion - thin uniform layer of soil removed Rill erosion - small rivulets of running water gather and cut small channels into the soil Gully erosion - rills enlarge to form channels too large to be removed by normal tillage Streambank erosion - washing away of soil from streambanks Wind can be just as harmful of an erosive force as water in dry flat land areas Intensive farming practices include: No crop rotation or resting periods Row crops leave soil exposed Weed-free fields Removal of wind breaks Monoculture Water: Ag largest share of global water use ~80% of water withdrawn for irrigation never reaches intended destination water logging and salinization Fertilizer: nitrogen, potassium and phosphorous stimulate plant growth 1950: avg of 20 kg/ha fertilizer used 2000: avg 90 kg/ha Alternate methods: manure and nitrogen-fixing bacteria US food systems: 16% of total energy use Pests: reduce crop yields and spoil ~50% annual harvest Crops without pesticides have less yield but less operating costs and ecological damage
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