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Study: Farming affects carbon levels

Agricultural production may release add’l greenhouse gases.
November 09, 2010

For many years, experts around the world have been making strides toward curbing world hunger, but researchers at the University of Minnesota and the University of Wisconsin have found another bump in the road.

In a study, researchers explain expanding cropland has negative effects on nature’s ability to store carbon.

Using land for agricultural production presents a tradeoff between feeding more people and releasing greenhouse gasses into the air, according to the study, published in the November issue of Proceedings of the National Academy of Sciences.

As more land is cleared to grow food, natural carbon stocks — carbon stored in trees, soil and other forms of vegetation — are released into the atmosphere, Jon Foley, a co-author of the study, said.

While data was analyzed on a global scale, researchers found the most pressing problem to be in tropical regions, where carbon loss is nearly twice as much for every 100 acres farmed than it is in temperate regions.

Newly cleared land in the tropics releases almost three tons of carbon for every one ton of annual crop yield, compared with every ton cleared in a temperate zone, the study reports.

While the carbon released in tropic areas doubles, the amount of food crops yielded from newly cleared areas is only half of what it might be on existing farmland, said Paul West, a co-author of the study and a researcher at the Center for Limnology at the UW-Madison.

The researchers said they hope the study will illustrate the need to find new methods to increase food production without contributing more to climate change.

“We can do that for sure by focusing on our already productive agriculture lands and see[ing] how we can increase food production

without clearing new areas,” said Foley, who is also the director of the University’s Institute on the Environment.

The authors agreed that while the task at hand is not an easy one, it is possible.

“We can look for mixtures of conventional and organic methods that increase soil fertility, water availability to crops and even work to use better genetics and crop varieties,” Foley said.

“Some work has shown that for each climate zone around the world for any given crop, there is a whole range of current crop yields,” he said. “What that indicates is that management practices in these places can have a tremendous amount of influence on actual crop production around the world.”

While the solutions may seem clear, the process of implementing them worldwide may not be.

“I think we can pull it off and, ultimately, we have to,” Foley said. “By improving agriculture and our food system in other regions, we can take the pressure off our remaining tropical forests, helping to preserve them for future generations.”

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