Ewing SA, GM Michalski, M Thiemens, RC Quinn, JL Macalady, S Kohl, SD Wankel, C Kendall, CP McKay, and R Amundson. 2007. The rainfall limit of the nitrogen cycle on earth. Global Biogeochemical Cycles. 21(3): 10.1029/2006GB002838.
Date Published:
August 8, 2007
C Kendall, CP McKay, GM Michalski, JL Macalady, M Thiemens, R Amundson, RC Quinn, S Kohl, SA Ewing, SD Wankel,

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 NO317O = 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.

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