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Nitrogen Study Could 'Rock' A Plant's World

Nitrogen Study Could 'Rock' A Plant's World

All plants need nitrogen to grow, and a new study says some plants get this nutrient from a surprising source. Conventional wisdom believes nitrogen for plants starts in the air and is converted by microbes in the soil into a usable form. But a report in the journal Nature finds that some nitrogen comes directly from rock. This discovery has implications for global warming.

DAVID GREENE, host:

Anyone with a green thumb will tell you that plants need nitrogen. Gardeners might use fertilizer, but in nature, the conventional wisdom is that air is the ultimate source of nitrogen for plants. It's converted to plant food by microbes underground. A new study, though, finds that conventional wisdom is wrong. NPR's Richard Harris explains that this could have some big implications for the planet.

RICHARD HARRIS: It's been such a central fact in botany that for many decades, nobody has bothered to question whether plants rely on the air for their nitrogen. Yet, there have been hints that the conventional wisdom is wrong.

Mr. BENJAMIN HOULTON (University of California, Davis Professor): If you go into most forest ecosystems for a long time it's been recognized that there's way too much nitrogen accumulating in soils and plants than could be explained by the atmosphere.

HARRIS: Benjamin Houlton, at the University of California, Davis, says you can add up all the nitrogen captured by microbes and you can add in the nitrogen particles that fall in the forest in the rain, but you still come up short.

So where else could forest nitrogen be coming from? Houlton was chatting about this with a colleague one day, and they started mulling over an idea that had been discarded long ago. That's the notion that significant amounts of nitrogen could leach out of sedimentary rocks. It seemed like a long shot to revisit this idea, but what the heck.