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- Title
Soil Carbon Change through 2 m during Forest Succession Alongside a 30-Year Agroecosystem Experiment.
- Authors
Devine, Scott; Markewitz, Daniel; Hendrix, Paul; Coleman, David
- Abstract
Forest succession (FS) and no-till (NT) agriculture are generally assumed to have a beneficial effect on surficial soil organic C (SOC) stocks compared with conventional tillage (CT) management; however, land use effects to depths >30 cm remain uncertain. In this research we compared SOC contents and composition to 2 m under CT, NT, and FS at the 30-year Horseshoe Bend agroecosystem experiment in Athens, Georgia, USA. Soils from 0 to 2 m were fractionated into particulate organic C (POC) (53-2000 μm) and fine C (<53 μm) fractions, and bulk soil δ13C signatures were determined. Soils from 0 to 28 cm were dry- and wet-sieved to estimate aggregate stability. Soil solutions were also collected at 0, 15, and 100 cm for dissolved organic C (DOC) analysis. Full-profile (0-2 m) SOC storage is 52 Mg ha-1 in CT, 60 Mg ha-1 in NT, and 62 Mg ha-1 in FS. Significant differences are limited to 0-5 cm and are linked to enhanced aggregate stability under NT and FS. Increases in subsoil POC under FS and changes in soil δ13C and C/N ratio indicate that substantial subsoil C cycling has occurred. DOC fluxes at 0 cm were significantly greater under NT (200 kg ha-1 year-1) and FS (210 kg ha-1 year-1) than under CT (80 k ha-1 year-1). DOC fluxes at 15 cm are estimated to be 20kg ha-1 year-1 under CT and NT and 40 kg ha year-1 under FS. At 100 cm, DOC fluxes are 2 kg ha-1 year-1, regardless of land use. An increase in FS POC of 2 Mg ha1 from 15 to 100 cm outweighs cumulative differences in DOC input to this layer, implicating deep forest rooting and bioturbation as active mechanisms in subsoil C change. Whereas differences in SOC content were concentrated near the surface, dynamic changes in C cycling extend well below the plow layer.
- Subjects
HORSESHOE Bend (Idaho); IDAHO; CARBON in soils; FOREST succession; NO-tillage; SOIL structure
- Publication
Forest Science, 2011, Vol 57, Issue 1, p36
- ISSN
0015-749X
- Publication type
Article
- DOI
10.1093/forestscience/57.1.36