WASHINGTON, April 5 (Xinhua) -- A study published on Thursday in the journal Science indicated that more than a quarter of nitrogen on Earth came from bedrock instead of coming from the atmosphere as previously thought.
This newly identified source of nitrogen could feed the carbon cycle on land, allowing ecosystems to pull more emissions out of the atmosphere.
Scientists from the University of California, Davis found that up to 26 percent of the nitrogen in natural ecosystems is sourced from rocks, with the remaining fraction from the atmosphere.
"Our study shows that nitrogen weathering is a globally significant source of nutrition to soils and ecosystems worldwide," said co-lead author Ben Houlton. "We think that this nitrogen may allow forests and grasslands to sequester more fossil fuel CO2 emissions than previously thought."
Researchers said that ecosystems need nitrogen and other nutrients to absorb carbon dioxide pollution, but there is a limited amount of it available from plants and soils.
If a large amount of nitrogen comes from rocks, it helps explain how natural ecosystems like boreal forests are capable of taking up high levels of carbon dioxide, they said.
However, they found not just any rock can leach nitrogen. Rock nitrogen availability is determined by weathering through tectonic movement or when minerals react with rainwater.
It helped explain why large areas of Africa are devoid of nitrogen-rich bedrock while northern latitudes have some of the highest levels of rock nitrogen weathering.
The study has found mountainous regions like the Himalayas and Andes are estimated to be significant sources of rock nitrogen weathering, similar to those regions' importance to global weathering rates and climate.
Also, grasslands, tundra, deserts and woodlands experience sizable rates of rock nitrogen weathering.
"Humanity currently depends on atmospheric nitrogen to produce enough fertilizer to maintain world food supply. A discovery of this magnitude will open up a new era of research on this essential nutrient," said Kendra McLauchlan, program director in the National Science Foundation's Division of Environmental Biology, which co-funded the research.
But according to the researchers, the work does not hold immediate implications for farmers and gardeners, who greatly rely on nitrogen in natural and synthetic forms to grow food.
