Biogeochemistry

, Volume 86, Issue 1, pp 19–31

Soil carbon saturation: concept, evidence and evaluation

Authors

    • A242 Natural Resource Ecology LaboratoryColorado State University
  • Keith Paustian
    • A242 Natural Resource Ecology LaboratoryColorado State University
    • Department of Soil and Crop SciencesColorado State University
  • Richard T. Conant
    • A242 Natural Resource Ecology LaboratoryColorado State University
  • Alain F. Plante
    • A242 Natural Resource Ecology LaboratoryColorado State University
    • Department of Earth and Environmental ScienceUniversity of Pennsylvania
  • Johan Six
    • A242 Natural Resource Ecology LaboratoryColorado State University
    • Department of Plant SciencesUniversity of California
Original Paper

DOI: 10.1007/s10533-007-9140-0

Cite this article as:
Stewart, C.E., Paustian, K., Conant, R.T. et al. Biogeochemistry (2007) 86: 19. doi:10.1007/s10533-007-9140-0

Abstract

Current estimates of soil C storage potential are based on models or factors that assume linearity between C input levels and C stocks at steady-state, implying that SOC stocks could increase without limit as C input levels increase. However, some soils show little or no increase in steady-state SOC stock with increasing C input levels suggesting that SOC can become saturated with respect to C input. We used long-term field experiment data to assess alternative hypotheses of soil carbon storage by three simple models: a linear model (no saturation), a one-pool whole-soil C saturation model, and a two-pool mixed model with C saturation of a single C pool, but not the whole soil. The one-pool C saturation model best fit the combined data from 14 sites, four individual sites were best-fit with the linear model, and no sites were best fit by the mixed model. These results indicate that existing agricultural field experiments generally have too small a range in C input levels to show saturation behavior, and verify the accepted linear relationship between soil C and C input used to model SOM dynamics. However, all sites combined and the site with the widest range in C input levels were best fit with the C-saturation model. Nevertheless, the same site produced distinct effective stabilization capacity curves rather than an absolute C saturation level. We conclude that the saturation of soil C does occur and therefore the greatest efficiency in soil C sequestration will be in soils further from C saturation.

Keywords

AgroecosystemsCarbon saturationSoil carbon sequestrationSoil carbon modelingTillage

Copyright information

© Springer Science+Business Media B.V. 2007