[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/03/EW-05-07-12-Nitrogen.mp3|titles=EW 05-07-12 Nitrogen]
Nitrogen is a key plant nutrient. And all of our plants grow in an atmosphere that is saturated with nitrogen—78 percent of the air we breathe is nitrogen.
But that atmospheric nitrogen is of no use to plants or animals. It has to go through a process called fixation in order to be available as a nutrient. Nitrogen fixation is performed by microbes or achieved as a side effect of high-temperature combustion. Lightning also fixes nitrogen by converting it to nitrogen oxides. And so does the combustion in power plants and in your car’s internal combustion engine.
With our increased automobile and energy usage, we’re adding more and more fixed nitrogen to the atmosphere. You’d think that would be a good thing for plants.
“By our combustion processes, we’ve increased the amount of nitrogen in the atmosphere and the amount that falls down on ecosystems.”
At the Cary Institute, forest ecologist Gary Lovett has been studying this.
“And we’re trying to examine the effect of all that increased nitrogen deposition, as we call it. We do that by accelerating the amount of nitrogen that’s being added to forest ecosystems by adding nitrogen fertilizer. We find that when we do that, we expected initially that the forest would grow better as a result of the nitrogen fertilizer, we found that they didn’t. In fact, in some cases, it acidified the soil and killed the trees.”
The fact is that excess nitrogen may go beyond being a nutrient and become a pollutant instead. Furthermore, some of the nitrogen deposited to land will eventually run off into streams, lakes, and oceans, potentially causing fish die-offs and red tide.
That’s why we should limit nitrogen fixation by reducing emissions from tailpipes and power plants.
Web Extra
Gary Lovett, a forest ecologist at the Cary Institute, explains exactly how excess nitrogen could become a pollutant…
[audio:http://wamcradio.org/EarthWise/wp-content/uploads/2012/03/lovett_web_extra.mp3|titles=lovett_web_extra]Links
Gary Lovett’s research summary
http://www.caryinstitute.org/people_sci_lovett_Catskills.html#control
Nitrogen Pollution: From the Sources to the Sea (Hubbard Brook Research Foundation)
http://hubbardbrookfoundation.org/12-2/nitrogen-pollution/
Photo, taken on December 28, 2007 using a Canon PowerShot A710 IS, courtesy of John Duffell via Flickr.