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Rainfall limit of the N cycle on Earth

January 1, 2007

In most climates on Earth, biological processes control soil N. In the Atacama Desert of Chile, aridity severely limits biology, and soils accumulate atmospheric NO3. We examined this apparent transformation of the soil N cycle using a series of ancient Atacama Desert soils (>2 My) that vary in rainfall (21 to <2 mm yr−1). With decreasing rainfall, soil organic C decreases to 0.3 kg C m−2 and biological activity becomes minimal, while soil NO3 and organic N increase to 4 kg N m−2 and 1.4 kg N m−2, respectively. Atmospheric NO3 (Δ17O = 23.0‰) increases from 39% to 80% of total soil NO3 as rainfall decreases. These soils capture the transition from a steady state, biologically mediated soil N cycle to a dominantly abiotic, transient state of slowly accumulating atmospheric N. This transition suggests that oxidized soil N may be present in an even more arid and abiotic environment: Mars.

Publication Year 2007
Title Rainfall limit of the N cycle on Earth
DOI 10.1029/2006GB002838
Authors Stephanie A. Ewing, Greg Michalski, Mark Thiemens, R.C. Quinn, J. L. Macalady, S. Kohl, Scott D. Wankel, Carol Kendall, Christopher P McKay, Ronald Amundson
Publication Type Article
Publication Subtype Journal Article
Series Title Global Biogeochemical Cycles
Index ID 70031179
Record Source USGS Publications Warehouse
USGS Organization Toxic Substances Hydrology Program