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Chapter 8. Raising Land Productivity: Introduction
From the beginning of agriculture until 1950 or so, growth in world food production came almost entirely from expanding the cultivated area. Rises in land productivity were negligible, scarcely perceptible from one generation to the next. Then as the frontiers of agricultural settlement disappeared, the world began systematically to raise land productivity. Between 1950 and 2000, grainland productivity climbed by 160 percent while the area planted in grain expanded only 14 percent.1
This extraordinary rise in productivity, combined with the modest expansion of cultivated area, enabled farmers to triple the grain harvest over the last half-century. At the same time, the growing demand for animal protein was being satisfied largely by a quintupling of the world fish catch to 95 million tons and a doubling of world beef and mutton production, largely from rangelands. These gains not only supported a growth in population from 2.5 billion to 6.1 billion, they also raised food consumption per person, shrinking the share who were hungry.2
As we look ahead at the next half-century, we face a demand situation that is similar in that the world is facing a projected increase of nearly 3 billion people, only slightly less than during the last half-century, but now virtually all the increase is coming in developing countries. In 1950, most of the world wanted to move up the food chain, eating more livestock products. That is also true today, but instead of 2 billion wanting to move up the food chain, there are now close to 5 billion.3
With agricultural supply, however, there are sharp differences. The annual rise in land productivity, averaging 2.1 percent from 1950 to 1990, dropped to 1 percent from 1990 to 2002. In addition, oceanic fisheries and rangelands have been pushed to their limits and beyond, which means we cannot expect much, if any, additional output from either system. Future gains in animal protein production will have to come largely from feeding grain to animals, whether they be livestock, poultry, or fish. And this means more demands on the world's croplands.4
At the center of the tripling of world grain production during the last century were high-yielding varieties, the dwarf wheats and rices developed originally in Japan and hybrid corn from the United States. Under favorable conditions, these varieties could double, triple, even quadruple the yields of traditional varieties. But there are no new varieties in the pipeline that can lead to similar quantum jumps in yields. Nearly two decades have passed since the first genetically modified crop varieties were released, yet biotechnologists have yet to produce a single variety of wheat, rice, or corn that can dramatically raise yields. Nor does it seem likely that they will, simply because plant breeders, using conventional breeding techniques, have already taken most of the obvious measures to get the big jumps in yields.5
Helping to realize the genetic potential of the new high-yield varieties was the growth in irrigation, which expanded from 94 million hectares in 1950 to 272 million in 2000, raising the share of the world's grain harvest from irrigated land to 40 percent. Now growth in the irrigated area is slowing as many countries lose irrigation water from aquifer depletion and its diversion to cities.6
As high-yielding varieties spread and irrigated area expanded, fertilizer use climbed from 14 million tons in 1950 to 137 million tons in 2000—a tenfold gain. While irrigation was removing the moisture constraints on crop yields, fertilizer was removing nutrient constraints. Then diminishing returns set in and the growth in fertilizer use slowed markedly. In the United States, Western Europe, and Japan, use has not increased for more than a decade. It may also now be leveling off in China, the world's largest user of fertilizer. There are still many countries that can profitably increase fertilizer use, including India and Brazil. But for much of the world, applying more fertilizer now has little effect on yields.7
Looking back, the greatest progress in eradicating hunger came while grain production per person was climbing from 251 kilograms in 1950 to 344 kilograms in 1984. During these 34 years, the rising tide of food production was reducing hunger throughout the world. After 1984, however, growth in the grain harvest slowed, falling behind that of population. By 2002, it had fallen to 290 kilograms per person, a decline of 18 percent from the peak in 1984.8
1. U.S. Department of Agriculture (USDA), Production, Supply, and Distribution, electronic database, updated 13 May 2003.
2. Animal protein from U.N. Food and Agriculture Organization (FAO), FAOSTAT Statistics Database, at apps.fao.org, livestock data updated 9 January 2003; population from United Nations, World Population Prospects: The 2002 Revision (New York: February 2003); world fish catch from FAO, Yearbook of Fishery Statistics: Capture Production and Aquaculture Production (Rome: various years).
3. United Nations, op. cit. note 2.
4. Land productivity from USDA, op. cit. note 1.
5. Thomas R. Sinclair, "Limits to Crop Yield," paper presented at the 1999 National Academy Colloquium, Plants and Populations: Is There Time? Irvine, CA, 5-6 December 1998.
6. FAO, FAOSTAT, op. cit. note 2, irrigation data updated 7 August 2002.
7. Ibid., fertilizer use data updated 1 April 2003.
8. USDA, op. cit. note 1; United Nations, op cit. note 2.
Copyright © 2003 Earth Policy Institute