Tropical agriculture "double-whammy": high emissions, low yields

Food produced in the tropics comes with high carbon emissions and low crop yields, according to a new study in the Proceedings of the National Academy of Sciences (PNAS). In the most comprehensive and detailed study to date looking at carbon emissions versus crop yields, researchers found that food produced in the tropics releases almost double the amount of carbon while producing half the yield as food produced in temperate regions. In other words, temperate food production is three times more efficient in terms of yield and carbon emissions.

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"Tropical forests store a tremendous amount of carbon, and when a forest is cleared, not only do you lose more carbon, but crop yields are not nearly as high as they are in temperate areas," explains lead author Paul C. West, a graduate student at the University of Wisconsin-Madison, in a press release.

The researchers found that one ton of food emitted approximately over 75 tons of carbon in the tropics, whereas a ton of food grown in temperate regions released just less than 27 tons of carbon.

"This creates a kind of 'double whammy' for a lot of tropical agriculture: we have to clear carbon-rich ecosystems to create tropical croplands, and unfortunately they often have lower yields than temperate systems," says co-author Jonathan Foley, director of the University of Minnesota's Institute on the Environment. "In terms of balancing the needs of food production and slowing carbon dioxide emissions, this is a tough tradeoff."

Article continues: http://news.mongabay.com/2010/1102-hance_tropical_agriculture.html