Rainfall limit of the N cycle on Earth

	Become an AGU Member Subscribe to AGU Journals



Read Full Article (file size: 498335 bytes) Cited by GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 21, GB3009, doi:10.1029/2006GB002838, 2007 Rainfall limit of the N cycle on Earth Stephanie A. Ewing Division of Ecosystem Sciences, Department of Environmental Science Policy and Management, University of California, Berkeley, California, USA Greg Michalski Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana, USA Mark Thiemens Division of Physical Sciences, University of California, San Diego, La Jolla, California, USA Richard C. Quinn SETI Institute, NASA Ames Research Center, Moffett Field, California, USA Jennifer L. Macalady Penn State Astrobiology Research Center, Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, USA Steven Kohl Division of Atmospheric Sciences, Desert Research Institute, Reno, Nevada, USA Scott D. Wankel U.S. Geological Survey, Menlo Park, California, USA Carol Kendall U.S. Geological Survey, Menlo Park, California, USA Christopher P. McKay NASA-Ames Research Center, Moffett Field, California, USA Ronald Amundson Division of Ecosystem Sciences, Department of Environmental Science Policy and Management, University of California, Berkeley, California, USA Abstract 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. Received 9 September 2006; accepted 23 May 2007; published 8 August 2007. Index Terms: 0469 Biogeosciences: Nitrogen cycling; 0428 Biogeosciences: Carbon cycling (4806); 0454 Biogeosciences: Isotopic composition and chemistry (1041, 4870); 0486 Biogeosciences: Soils/pedology (1865). Read Full Article (file size: 498335 bytes) Cited by Citation: Ewing, S. A., G. Michalski, M. Thiemens, R. C. Quinn, J. L. Macalady, S. Kohl, S. D. Wankel, C. Kendall, C. P. McKay, and R. Amundson (2007), Rainfall limit of the N cycle on Earth, Global Biogeochem. Cycles, 21, GB3009, doi:10.1029/2006GB002838. Copyright 2007 by the American Geophysical Union.

Abstract