YSCN0037 Feeding the World - sustainability-3 (2)

YSCN0037 Feeding the World - sustainability-3 (2) -...

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YSCN0037 Feeding the World Ways to achieve sustainability
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Why do we get cheaper food than before? Overall trends of agriculture in the last century World grain harvest has quadrupled in the last century. Mostly happened in the latter half of the century: more than tripled since 1950 from 630 million to about 2 billion tons in 2000 Before the mid-twentieth century, the growth in harvest is largely based on the expansion of crop areas and the natural yield increases are too slow to be noticeable in human lifespan. However, such a large expansion of framing lands is no longer possible as most of the “remaining” lands are natural rainforests or deserts which cannot be utilized easily .
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Overall trends of agriculture in the last century Rapid growth of crop production in the past 40 years is largely based on yield increases instead. From 1950 to 1990 (after the “green revolution”), the global grain production increased by 250%. and the average grain yield increased from less than 1.1 tons per hectare to close to 2.5 tons. (~230%) The yield of other crops also shows the same trend. For example, the world soybean harvest had increased from 68 million tonnes in 1984 to 222 million tons in 2007.
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Overall trends of agriculture in the last century The increases in yields are caused by the systematic application of science to agriculture. The growth in the land productivity is driven by three trends increase in irrigated area the extensive use of fertilizer the rapid use of the high-yielding varieties The different aspects of industrial farming ensure a relatively stable and cheap food supply to people in the developed and many of the developing countries. However, recent food security is not sustainable. The worldwide grain land productivity increases at a rate of 2.1% per year during 1950-1990. After 1990, the rise has slowed to 1.2% per year.
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“2007-08 Food Crisis” In the past century, the food prices have been steadily decreasing. For instance, the percentage of U.S. disposable income spent on food prepared at home decreased from 22 percent as late as 1950 to 7 percent by the end of the century. However, the price reaches a minimum around 2000 After 2000 (from 2000-2004), the prices of various foods have generally increased (from the minimum in ~2000) and the increasing trend roughly follows that of oil prices at the same time. As the oil price increased to around US$100 (in 2006), the production of biofuels had grown quickly and its share of the U.S. grain harvest going to ethanol distilleries escalated. This reduces the cereal production used for human consumption.
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Although the production of cereals generally increased in past decades, extreme weather events in several cereal producing countries during 2006-2008 resulted in the depletion of cereal stocks . In this period, the world had produced
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This note was uploaded on 12/08/2010 for the course SCIENCE 0037 taught by Professor Dr. during the Spring '10 term at HKU.

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YSCN0037 Feeding the World - sustainability-3 (2) -...

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