**The nitrogen that atmospheric agents extract from the rocks represents a significant portion of this important nutrient of plants, well above what has been believed up until now. The discovery will have repercussions on climate models, since the nitrogen cycle influences the carbon cycle by sequestration of carbon dioxide by vegetation.**

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A significant fraction of the nitrogen needed by plants comes from rocks exposed to the elements and does not derive, as was thought, almost exclusively from the atmosphere, from which it is extracted and made available by so-called nitrogen-fixing bacteria. This is the conclusion reached by researchers at the University of California at Davis, who sign [an article published in "Science"](http://science.sciencemag.org/content/360/6384/58) . The discovery will allow to improve climatological models because the availability of this nitrogen source, strongly variable from one region to another of the globe, influences the ability of plants to sequester carbon dioxide. 

The availability of rocky nitrogen is primarily determined by atmospheric agents, which allow the triggering of chemical reactions between the minerals present in the rocks and rainwater and therefore the release of the element into the environment. But also other chemical reactions and tectonic movements contribute to this process. 


According to the study, the amount of nitrogen available to plants coming from rocks varies globally from 8 to 26 percent, for an estimated total value between 19 and 31 million tons of nitrogen per year. The size of the release changes from region to region and depends on the type of soil, reaching the maximum values ​​at the northern latitudes. This helps to explain why boreal forests are able to absorb particularly high levels of carbon dioxide. Even the pastures and tundra of those regions have high levels of rocky nitrogen. 

According to the authors' estimates, also mountainous regions such as the Himalayas and the Andes are significant sources of nitrogen released by rocks due to the action of atmospheric agents. On the contrary, large parts of Africa are without a nitrogen-rich rocky substratum. 

>"Nitrogen is the most important limiting nutrient of the Earth but in certain situations it is also a dangerous pollutant, so it is important to understand the factors of natural control of this element," said Kendra McLauchlan of the National Science Foundation, who financed the search. "Humanity is currently dependent on atmospheric nitrogen to produce sufficient fertilizers to maintain world food supply, and a discovery of this magnitude will open a new era of research on this essential nutrient."


### References for Further Reading

[Phys](https://phys.org/news/2018-04-source-global-nitrogen.amp)

[Science Daily](https://www.sciencedaily.com/releases/2018/04/180405140946.htm)