Read the full article on the Earth & Environmental Sciences Area (EESA) website.

At a glance, nitrogen seems to be an extremely abundant element, comprising nearly 80% of Earth’s atmosphere. But for organisms to actually access nitrogen–an essential building block for proteins, DNA molecules, and more–the element must be “fixed” by bacteria that convert atmospheric nitrogen into a usable form through a process known as nitrogen fixation. This makes nitrogen a primary limiting nutrient in many ecosystems, largely affecting the growth of plants along with ecosystem diversity, productivity, and resilience.

A recent study led by EESA postdoctoral researcher Kelsey Crutchfield-Peters took to the field to explore nitrogen cycling in an deep old growth forest rhizosphere–a region of the subsurface composed of plant roots and their microbiomes–where nutrient uptake has been largely unexplored. The study, published in the Proceedings of the National Academy of Sciences, found that dissolved nitrogen in deep weathered bedrock was an order of magnitude higher than in upper-layer soils, where most nutrient uptake is assumed to occur. The team’s findings from this forest subsurface in particular, with roots extending meters into underlying weathered bedrock beyond thin soils, can help to expand our understanding of where plants get nutrients, and suggests that ecosystem models and nitrogen budgets may be missing a major piece of the nitrogen story.