Relative stability of soil carbon revealed by shifts in ?¹⁵N and C:N ratio

F. Conen (1) , M. Zimmermann (2) , J. Leifeld (3) , B. Seth (1) , C. Alewell (1)

1 Institute of Environmental Geosciences
2 School of Geosciences [Edinburgh]
3 Research Station ART

Life on earth drives a continuous exchange of carbon between soils and the atmosphere. Some forms of soil carbon, or organic matter, are more stable and have a longer residence time in soil than others. Relative differences in stability have often been derived from shifts in ?¹³C (which is bound to a vegetation change from C3 to C4 type) or through ¹⁴C-dating (which is bound to small sample numbers because of high measurement costs). Here, we propose a new concept based on the increase in ?¹⁵N and the decrease in C:N ratio with increasing stability. We tested the concept on grasslands at different elevations in the Swiss Alps. Depending on elevation and soil depth, it predicted mineral-associated organic carbon to be 3 to 73 times more stable than particulate organic carbon. Analysis of ¹⁴C-ages generally endorsed these predictions.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

F. Conen, M. Zimmermann, J. Leifeld, B. Seth, C. Alewell. Relative stability of soil carbon revealed by shifts in ?¹⁵N and C:N ratio. Biogeosciences Discussions, 2007, 4 (4), pp.2915-2928. ⟨hal-00297914⟩