Sunday, April 19, 2015

Soy beans cost more because of climate change

http://www.sciencedaily.com/releases/2015/03/150330162427.htm






Even during a good year, soybean farmers nationwide are, in essence, taking a loss. That's because changes in weather patterns have been eating into their profits and taking quite a bite: $11 billion over the past 20 years.

This massive loss has been hidden, in effect, by the impressive annual growth seen in soybean yields thanks to other factors. But that growth could have been 30 percent higher if weather variations resulting from climate change had not occurred, according to a study by University of Wisconsin-Madison agronomists published last month in Nature Plants.

Averaging the data across the United States, researchers found that soybean yields fell by around 2.4 percent for every one-degree rise in temperature. In Wisconsin and most other northern states, including South Dakota and Minnesota, the changes in climate factors actually led to higher soybean yields. Wisconsin, for instance, saw an increase of 17.5 kilograms per hectare per year over the 20 years studied. However, most soybean-growing states farther south, including Ohio, Arkansas and Kentucky, experienced decreases in yields.
These divergent responses have to do with historical norms. In colder northern states, soybeans seem to be enjoying the new warmer weather, while in states farther south -- where conditions had previously been fairly ideal -- the additional heat is causing stress.
Conley's team isolated the impacts of changing temperature and precipitation on soybean yields in a much more precise way than previously done. While earlier approaches relied on estimates, UW-Madison researchers gathered their own data field trials, giving them access to more reliable and consistent information about the genetics of the soybeans being grown, the management practices being used and the weather the fields saw throughout the growing season. Spyridon Mourtzinis, a post-doctoral fellow in Conley's lab, then removed the effects of the management strategies and genetic improvements so the team could focus their analysis on the impacts of weather variability.

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