Technological Trajectories and the Human Environment (1997) / Chapter Skim
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How Much Land Can Ten Billion People Spare for Nature?
How Much Land Can Ten Billion People Spare for Nature?
Pages 56-73
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From page 56... ...
How Much Land Can Ten Billion People Spare for Nature?
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From page 57... ...
Looking back from 1994 to 1961-1966 one can see that Indian farmers spared 44 million ha, about the area of California, by growing more per hectare (see Figure 11. "How much land can ten billion people spare for Nature?
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From page 58... ...
The calories and protein for draft animals require some explanation: they represent consumption by the animals. In 1910 the horses and mules on Amencan farms and in Amencan cities consumed feed that was grown on an area 44 percent as large as that used to cultivate products for domestic use; their replacement by tractors and trucks has been blamed for the American grain surplus of the 1930s (lIassebrook and Hegyes, 1989; US Department of Agnculture, 1962~.
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From page 59... ...
Even efficient broiler chickens put only about a fifth of the calories they eat into meat.2 Grazing animals eat more than feed crops, so agriculture, if not cropland, must be credited with some part of the animal calories. Allowing for some further release of calories by reduction in animal numbers but also a continuing role for draft animals, I add 200 calories to the 2,900 calories in crops, bringing the total for ten billion people to 3,100 calories.
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From page 60... ...
But globally the water on land far exceeds the amount needed to grow food for ten billion people.4 Although cropland per capita expanded from the year 1700 to 1950, it has since shrunk while per capita food production has risen (Richards, 1990; FAO, 1992. Having techniques that raise yield per hectare and having farmers use these techniques are clearly preeminent in this historic reversal.
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From page 61... ...
At eighty people per hectare, 125 million ha, or less than a tenth of the present cropland, could support a population of ten billion. In Figure 4 a logistic curve rises with the actual average American maize yields toward the limit of the winning 1992 yield.
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From page 62... ...
For example, in the early 1970s fallen production drove food prices up, and US soybean prices doubled. Anxious academics and politicians launched world hunger studies.
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From page 63... ...
grown by the winners of the Iowa Master Corn Growers' Contest and also of average yields of Iowa and world farmers. NOTE: The rising trend of per-year yields for Iowa Masters is 1.1 percent, or 0.14 t/ha; for Iowa, the average is 1.S percent, or 0.10 t/ha; and for world maize growers, the average is 2.2 percent, or 0.06 t/ha.
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From page 64... ...
A reasonable analysis can produce an annual decline of food prices of 0.5 percent, which matches the 1900-1984 fall of world prices of the main agricultural products.6 DOES WATER CLOUD THE VISION? Despite the abundance of water overall, its uneven distribution among regions and its capricious variation among seasons plague farming.
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From page 65... ...
HOW MUCH WILL HIGH YIELDS TARNISH THE LAND? If farmers increase their yields with techniques that harm the surroundings, they will spare land, but the external effects may tarnish their victories.
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From page 66... ...
Looking forward, the Dutch projected changes from the present farmland in nations of the European Union to the year 2015 (Rabbinge et al., 1992~. Diverse scenarios built around liberal trade, employment policies, and environmental regulation all shrank farmland by 40 percent or more.
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From page 67... ...
On the other hand, an average yield of 16 Mcal/ha, one-third less than present European wheat, would spare much of the land. Averaging 16 Mcal/ha, farmers would be able to support ten billion people consuming 6,OOO car/day on the present cropland, sparing half of the reference area.
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From page 68... ...
8 FIGURE 7. The sparing for Nature of a reference area of 2.8 billion hectares of cropland by farmers raising yields for ten billion people consuming 3,000 or 6,000 calories daily.
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From page 69... ...
New, surprising fungi caused both the Irish potato famine of the 1840s and the Southern corn leaf blight of 1970. "History warns that new pests will appear but provides no data for a model that tells where and when newcomers will appear or what they will be like.
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From page 70... ...
Although the uneven distribution of water among regions and its capricious variation among seasons plague farming, opportunities to raise more crops with the same volume of water kindle our hopes for the spread of high yields. Rising yields have shrunk European and American cropland for decades, and governments pay farmers to keep fields idle.
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From page 71... ...
. is that 1,000 billion people could live from the earth if photor!
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From page 72... ...
1990. Approaches to mitigate tropical deforestation by sustainable soil management practices.
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From page 73... ...
1994. How Much Land Can Ten Billion People Spare for Nature?
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