Microbe diet key to carbon dioxide release

August 1st, 2008 - 1:33 pm ICT by IANS  

Washington, Aug 1 (IANS) Microbes help decompose plant matter, enriching the soil with nutrients and releasing the greenhouse gas carbon dioxide into the atmosphere. Duke University scientists found that the ratio of nitrogen to carbon in this organic matter ensures how much nitrogen is available to plants and how much carbon dioxide is released.

“We have been able to demonstrate that the pattern of carbon dioxide release through decomposition is governed by the same properties everywhere, from the Arctic Circle to tropical rain forests,” said the study’s co-author Stefano Manzoni.

Manzoni works in the lab of Amilcare Porporato, associate professor in Duke’s Pratt School of Engineering.

During decomposition, microbes digest fallen organic matter from plants and slowly break it down. Two of the important byproducts of this process are mineral nitrogen and carbon dioxide (CO2).

Nitrogen is an essential nutrient for both plants and microbes, and once it becomes mineralised, it becomes available for plants to use.

Carbon - the most abundant element in plants and organic matter - is released into the atmosphere as CO2, a greenhouse gases responsible for global warming.

“When their diet is lacking in nitrogen, microbes tend to react by releasing more CO2 and taking in less mineral nitrogen from the soil. So plants can get the much-needed mineralised nitrogen earlier in decomposition process from the fallen organic matter.” Porporato said.

For the analysis, Manzoni assembled a database of more than 2,800 samples of decomposing plant matter from worldwide locations.

The results of the Duke analysis were published in Science Friday.

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