A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence
Article first published online: 20 DEC 2002
Copyright 2002 by the American Geophysical Union.
Global Biogeochemical Cycles
Volume 16, Issue 4, pages 82-1–82-26, December 2002
How to Cite
A multiisotope C and N modeling analysis of soil organic matter turnover and transport as a function of soil depth in a California annual grassland soil chronosequence, Global Biogeochem. Cycles, 16(4), 1135, doi:10.1029/2001GB001823, 2002., , , , , and ,
- Issue published online: 20 DEC 2002
- Article first published online: 20 DEC 2002
- Manuscript Accepted: 31 JUL 2002
- Manuscript Revised: 5 JUL 2002
- Manuscript Received: 31 OCT 2001
- terrestrial ecosystem biogeochemistry model;
- soil organic matter dynamics;
- soil chronosequence
 We examine soil organic matter (SOM) turnover and transport using C and N isotopes in soil profiles sampled circa 1949, 1978, and 1998 (a period spanning pulse thermonuclear 14C enrichment of the atmosphere) along a 3-million-year annual grassland soil chronosequence. Temporal differences in soil Δ14C profiles indicate that inputs of recently living organic matter (OM) occur primarily in the upper 20–30 cm but suggest that OM inputs can occur below the primary rooting zone. A three-pool SOM model with downward transport captures most observed variation in Δ14C, percentages of C and N, δ13C, and δ15N, supporting the commonly accepted concept of three distinct SOM pools. The model suggests that the importance of the decadal SOM pool in N dynamics is greatest in young and old soils. Altered hydrology and possibly low pH and/or P dynamics in highly developed old soils cause changes in soil C and N turnover and transport of importance for soil biogeochemistry models.