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item Sinclair, Thomas

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/8/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The book SUGAR 2000 is to consider the many factors that will be influencing the future of the sugarcane industry world-wide. One important concern is that the yields of sugarcane have not increased in recent years. To set the stage for discussions on the stabilization in yields, Dr. Sinclair, USDA/ARS, Gainesville, FL, was asked to analyze the possible development of similar yield plateaus in grain crops. The analogy of a mountain range was used in this paper to analyze the basis for 'peak' crop yields and various 'plateaus' of yield. Indeed, yield plateaus in grain crops appear to have developed in industrialized countries. Importantly, the yield plateaus are not imposed by limits in agricultural technology, but are a result of socioeconomic factors. Economic pressures and environmental legislation have caused growers to no longer maximize yields, but accept grain crop yields at less than maximum yields.

Technical Abstract: An analogy to the topography of a mountain range is used to explore the various levels of crop yield. The peaks in crop yield are ultimately constrained by the amount of light energy that is available for use by plants to assimilate carbon. Although theoretical peak yields have been achieved experimentally, most crop yields are at lower levels constrained by the availability of resources. The resource plateaus for yield are set in many cases by the availability of either water or minerals, especially nitrogen. In industrialized countries, it appears that indeed yield plateaus have developed in the past ten years that are closely associated with fertilizer application. While it is possible for growers to raise the fertilizer plateau, socioeconomic factors have become important in establishing this plateau. Economic decisions to maximize profits rather than maximize yields, have become a new, important reality in leveling of crop yields. Also, societal pressures resulting from environmental and food safety concerns encourage crop production at less than maximum levels. Peak, or maximum, crop yields do not appear to be a realistic future objective for many cropping systems in view of these emerging socioeconomic plateaus.