Assessment of a Method to Measure Temporal Change in Soil Carbon Storage
- B. H. Ellert *,
- H. H. Janzen and
- T. Entz
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2002.