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- Title
Long term decomposition: the influence of litter type and soil horizon on retention of plant carbon and nitrogen in soils.
- Authors
Hatton, Pierre-Joseph; Hicks Pries, Caitlin; Castanha, Cristina; Torn, Margaret; Bird, Jeffrey
- Abstract
How plant inputs from above- versus below-ground affect long term carbon (C) and nitrogen (N) retention and stabilization in soils is not well known. We present results of a decade-long field study that traced the decomposition of C- and N-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.
- Subjects
PLANT litter decomposition; SOIL horizons; CARBON in soils; NITROGEN in soils; HUMUS analysis; SOIL stabilization; PONDEROSA pine
- Publication
Biogeochemistry, 2017, Vol 134, Issue 1-2, p5
- ISSN
0168-2563
- Publication type
Letter
- DOI
10.1007/s10533-017-0345-6