Green revolution myth and agricultural reality?

Author:DeGregori, Thomas R.
 
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A litany of mythical criticisms of the Green Revolution has so often been repeated and so widely disseminated that the critics' slogans have been accepted by many educated observers as unchallengeable fact. One of the slogans of critics of the Green Revolution is that the HYV (high-yielding variety) seeds require more fertilizer, water, and pesticides when in fact they outperform the traditional varieties at most any level of inputs.

The modern rice varieties have about a threefold increase in water productivity compared with traditional varieties. Progress in extending these achievements to other crops has been considerable and will probably accelerate following identification of underlying genes. (FAO 2003, 28) Overall, the best estimates are that "the water needs for food per capita halved between 1961 and 2001" (FAO 2003, 28).

Higher yields "require" more fertilizer as the more nutrient that is extracted from the soil, the more that has to be replaced. Norman Borlaug in his Nobel Prize acceptance speech stated: "If the high-yielding dwarf wheat and rice varieties are the catalysts that have ignited the Green Revolution, then chemical fertilizer is the fuel that has powered its forward thrust.... The new varieties not only respond to much heavier dosages of fertilizer than the old ones but are also much more efficient in their use" (1970).

The old tail-strawed varieties would produce only ten kilos of additional grains for each kilogram of nitrogen applied, while the new varieties can produce 20 to 25 kilograms or more of additional grain per kilogram of nitrogen applied. (Borlaug 1970) The Green Revolution seeds turn out to be more disease resistant (as plant breeders have added multiple disease resistant genes--gene stacking), requiring fewer pesticides. "Increasingly, scientists breed for polygenic (as opposed to monogenic) resistance by accumulating diverse, multiple genes from new sources and genes controlling different mechanisms of resistance within single varieties" (Smale 1997, 1265; see also Cox and Wood 1999, 46). The coefficient of variation for rice production has been steadily decreasing for the last forty years, which would seem to indicate the new technologies in agricultural production are hOt as fragile as some would have us believe (Lenne and Wood 1999). Wheat "yield stability, resistance to rusts, pedigree complexity, and the number of modern cultivars in farmers' fields have all increased since the early years of the Green Revolution" (Smale and McBride 1996).

Modern "monoculture" is central to the unverified claims about modern varieties being less disease resistant. Critics of modern agriculture who fear the susceptibility to disease from monoculture continually hark back to the southern corn-leaf blight in the United States in 1970 since they cannot come up with any other comparable loss in the last half-century in corn or wheat or rice, the staples that provide about two-thirds of the world's food production. The $1 billion in losses of about 15 to 25 percent of the 1970 corn crop was substantial, but these loses should be considered against the fact that corn yields had more than doubled over the previous two decades and that the crop year following the blight was one of record yields. From the first work in wheat in Mexico, it was clear that Green Revolution yield increases depended on both increases in plant production and decreases in crop losses. Since then, some of the most important and widely planted HYVs were bred from a multiplicity of varieties...

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