Desert Soils Losing Nitrogen & Fertility Thanks to Global Warming

mojave desert nitrogen test device
Photo: Device measuring outgassing of nitrogen from desert soil (Cornell University)
You may have heard of nitrogen being lost through processes such as soil erosion, but according to a new study from Cornell University, warming climates are also causing soils to lose nitrogen as a gas. Arid soils are particularly affected - and with nitrogen being one of the key nutrients for plant growth, the study predicts that deserts could support even less plant life in the future.

"This is a way that nitrogen is lost from an ecosystem that people have never accounted for before," says Jed Sparks, co-author of the study and associate professor of ecology and evolutionary biology. "It allows us to finally understand the dynamics of nitrogen in arid systems."

The findings, taken from tests in the Mojave Desert, represent a first attempt to look at abiotic (non-biological) factors of nitrogen loss in soils. Previously, scientists had only looked at biotic factors such as soil microbes releasing nitrogen into the air. However, the report predicts that with higher temperatures, non-biological causes account for heavier nitrogen losses. With shifting precipitation patterns added to the mix, the situation is made worse.

With deserts making up 35 to 40 percent of Earth's land surface, and arid and semiarid regions as being most likely to be chosen as new human habitats, the findings point to the potential of poorer air quality, soil infertility and increasing desertification.

"We're on a trajectory where plant life in arid ecosystems could cease to do well," says graduate student and co-author Carmody McCalley.

What is more unsettling is that most current climate models do not consider abiotic factors of nitrogen loss. Sparks and McCalley warn that climate models must be modified in order to accurately reflect what is going on.

"The [algorithmic] code in climate models would have to change to account for abiotic impacts on this part of the nitrogen budget," says McCalley.

Cornell Chronicle

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