Biogeochemistry

, Volume 86, Issue 1, pp 19–31

Soil carbon saturation: concept, evidence and evaluation

  • Catherine E. Stewart
  • Keith Paustian
  • Richard T. Conant
  • Alain F. Plante
  • Johan Six
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

Authors and Affiliations

  • Catherine E. Stewart
    • 1
  • Keith Paustian
    • 1
    • 2
  • Richard T. Conant
    • 1
  • Alain F. Plante
    • 1
    • 3
  • Johan Six
    • 1
    • 4
  1. 1.A242 Natural Resource Ecology LaboratoryColorado State UniversityFort CollinsUSA
  2. 2.Department of Soil and Crop SciencesColorado State UniversityFort CollinsUSA
  3. 3.Department of Earth and Environmental ScienceUniversity of PennsylvaniaPhiladelphiaUSA
  4. 4.Department of Plant SciencesUniversity of CaliforniaDavisUSA