ENV-1010 Lecture Notes - Lecture 16: Crop Yield, Multiple Cropping, Selective Breeding
13 Sep 2016
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Food resources: 3 main resources and % of world"s food, croplands 77, rangelands 16, ocean fisheries 7% Food production cropland: since 1950 > increase in global food production from mechanized farming. 90% of food comes from only 15 plants. 3 grain crops provide 50% of calorie intake. Agriculture systems: industrialized and traditional: 1. Machines, fossil fuel energy, water, fertilizers, and pesticides. 42% of world population provides 20% of world"s food supply. Very low-input agriculture mostly by human power. Produces just enough food for family: shifting agriculture, nomadic livestock herding. Increase human/animal labor plus application of fertilizer and extra water. Produces higher yield (family + crop to sell) Agricultural efficiency: u. s. industrial agriculture 2. 4% of labor force produces food, ldcs 45-65% of labor force produces food. 2nd green revolution 1970-present: developing countries especially tropical and subtropical, fast-growing dwarf varieties of rice and wheat with 2x to 5x more yield, such revolutions use machinery and fossil fuel to plant and harvest.
