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This article in SSSAJ

  1. Vol. 66 No. 5, p. 1687-1695
    Received: June 5, 2001

    * Corresponding author(s): ellert@em.agr.ca
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Assessment of a Method to Measure Temporal Change in Soil Carbon Storage

  1. B. H. Ellert *,
  2. H. H. Janzen and
  3. T. Entz
  1. Agriculture & Agri-Food Canada Research Centre, P.O. Box 3000, Lethbridge, AB, Canada T1J 4B1


Sensitive methods are essential to resolve small changes in soil C storage, such as those attained in sequestration projects, against much larger quantities of C already present. To measure temporal changes in C storage we proposed a high-resolution method based on collecting volumetric soil cores from a microsite (4 by 7 m), marking core locations to intersperse multiple cores collected initially and in a subsequent sampling year, rigorous analytical quality control, and calculating soil C pool sizes with proper corrections for unequal soil masses. To evaluate the method, we measured the recovery of 3.64 Mg C ha−1 added as coal dust to microsites. We calculated C stored in successive soil layers of both fixed volume and equivalent mass. We inferred coal C recovery from spatial comparisons between coal-amended and unamended plots, and from temporal comparisons between soil samples collected before and after coal addition. The comparisons among C storage showed effective recovery of added coal C, but only for paired temporal differences based on calculations of organic C storage in an equivalent soil mass. With spatial comparisons, coal C became undetectable when soil thickness exceeded 35 cm. With temporal comparisons, coal C recovery ranged from 91 to 106%, provided differences were calculated for successively thicker layers of equivalent soil mass. In contrast, recovery was only 64 to 82% when temporal differences were calculated for layers of fixed soil volume. The method is useful to quantify small temporal changes in soil organic C storage within microsites, and possibly over more extensive areas with sufficient samples to characterize spatial variability.

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Copyright © 2002. Soil Science SocietyPublished in Soil Sci. Soc. Am. J.66:1687–1695.