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Warmer Climates Don't Change Nitrogen Levels

Warmer Climates Don't Change Nitrogen Levels
Scientists find out their theories don't prove out related to climate change.

If you were into heavy reading, you might pick up a copy of Global Change Biology instead of Indiana Prairie Farmer. Assuming the journal is not on your normal reading list, you might miss an article by Jeff Dukes, professor in forestry and natural resources at Purdue University and co-authors relating to climate change.

No Help: A warmer climate wouldn't necessarily speed up release of nitrogen and prevent nitrogen deficiencies, a Purdue researcher concludes.

The theory in scientific circles up until now was that as the climate warmed, there would be more nitrogen available to make soils more fertile. This would happen because the microbes responsible for the nitrification process would speed up their activity. However, Dukes led a team that discovered that this is not the case. Increased temperatures on a permanent basis would not increase the soil fertility level by adding more nitrogen to the soil. The hypothesis, or best guess, of the scientists appears to have been wrong.

"More nitrogen being available in all ecosystems is not something we can count on," Dukes says.

The microbes that return nitrogen to the soil react differently to a range of climate conditions, Dukes says. Instead of making nitrogen cycling go faster, constant exposure to warmer temperatures may have little or no effect on the process in some ecosystems, the study authors conclude.

Scientists have already developed climate models indicating how plants would change growth habits in warmer environments. The end result of the models was that plant productivity would increase. Based on the new findings, Dukes and his staff believe that the models likely overestimated the increase in productivity. The extra N will not be released as the model assumed to make it happen.

Neither warming nor changes in precipitation changed the rate of return of nitrogen to the soil, they found. Instead, warming and drought caused the processes involved in the nitrogen cycle to become less sensitive to temperature effects.

The bottom line is that warmer climate did not change nitrogen breakdown levels based on their test results.

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