Rainfall limit of the N cycle on Earth
Article first published online: 8 AUG 2007
Copyright 2007 by the American Geophysical Union.
Global Biogeochemical Cycles
Volume 21, Issue 3, September 2007
How to Cite
2007), Rainfall limit of the N cycle on Earth, Global Biogeochem. Cycles, 21, GB3009, doi:10.1029/2006GB002838., , , , , , , , , and (
- Issue published online: 8 AUG 2007
- Article first published online: 8 AUG 2007
- Manuscript Accepted: 23 MAY 2007
- Manuscript Revised: 6 APR 2007
- Manuscript Received: 9 SEP 2006
 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.