Long term decomposition: the influence of litter type and soil horizon on retention of plant carbon and nitrogen in soils
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- City Univ. (CUNY), NY (United States)
- City Univ. (CUNY), NY (United States); Univ. of Michigan, Ann Arbor, MI (United States)
How plant inputs from above- versus below-ground affect long term carbon (C) and nitrogen (N) retention and stabilization in soils is not well understood. We present results of a decade-long field study that traced the decomposition of 13C- and 15N-labeled Pinus ponderosa needle and fine root litter placed in O or A soil horizons of a sandy Alfisol under a coniferous forest. We measured the retention of litter-derived C and N in particulate ( > 2 mm) and bulk soil ( < 2 mm) fractions, as well as in density-separated free light and three mineral-associated fractions. After 10 years, the influence of slower initial mineralization of root litter compared to needle litter was still evident: almost twice as much root litter (44% of C) was retained than needle litter (22–28% of C). After 10 years, the O horizon retained more litter in coarse particulate matter implying the crucial comminution step was slower than in the A horizon, while the A horizon retained more litter in the finer bulk soil, where it was recovered in organo-mineral associations. Retention in these A horizon mineral-associated fractions was similar for roots and needles. Nearly 5% of the applied litter C (and almost 15% of the applied N) was in organo-mineral associations, which had centennial residence times and potential for long-term stabilization. Vertical movement of litter-derived C was minimal after a decade, but N was significantly more mobile. Overall, the legacy of initial litter quality influences total SOM retention; however, the potential for and mechanisms of long-term SOM stabilization are influenced not by litter type but by soil horizon.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1379898
- Journal Information:
- Biogeochemistry, Journal Name: Biogeochemistry Journal Issue: 1-2 Vol. 134; ISSN 0168-2563
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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