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BioEnergy Research

, Volume 5, Issue 1, pp 124–138 | Cite as

Review and Model-Based Analysis of Factors Influencing Soil Carbon Sequestration Beneath Switchgrass (Panicum virgatum)

  • Charles T. GartenJr.Email author
Article

Abstract

A multi-compartment model was developed to summarize existing data and predict soil carbon sequestration beneath switchgrass (Panicum virgatum) in the southeastern USA. Soil carbon sequestration is an important part of sustainable switchgrass production for bioenergy because soil organic matter promotes water retention, nutrient supply, and soil properties that minimize erosion. A literature review was undertaken for the purpose of model parameterization. A sensitivity analysis of the model indicated that predictions of soil carbon sequestration were affected most by changes in aboveground biomass production, the ratio of belowground-to-aboveground biomass production, and mean annual temperature. Simulations indicated that the annual rate of soil carbon sequestration approached steady state after a decade of switchgrass growth while predicted mineral soil carbon stocks were still increasing. A model-based experiment was performed to predict rates of soil carbon sequestration at different levels of nitrogen fertilization and initial soil carbon stocks (to a 30-cm depth). At a mean annual temperature of 13°C, the predicted rate of soil carbon sequestration varied from −28 to 114 g C m−2 year−1 (after 30 years) and was greater than zero in 11 of 12 simulations that varied initial surface soil carbon stocks from 1 to 5 kg C m−2 and nitrogen fertilization from 0 to 18 g N m−2 year−1. The modeling indicated that more research is needed on the process of biomass allocation and on nitrogen loss from mature plantations, respectively, to improve our understanding of carbon and nitrogen dynamics in switchgrass agriculture.

Keywords

Switchgrass Modeling Soil carbon Carbon sequestration Bioenergy Review 

Abbreviations

AAP

Adjusted aboveground production

AGC

Nitrogen concentration in aboveground biomass

AGN

Annual aboveground nitrogen uptake

ANP

Annual aboveground production

ANT

Annual nitrogen inputs to the field

APP

Aboveground biomass production without fertilization

ARC

Annual rate of soil carbon sequestration

AVN

Available soil nitrogen

BGN

Annual belowground nitrogen uptake

BGP

Annual belowground production

BSC

Initial soil carbon stock

CHR

Cumulative harvest of aboveground biomass

CLR

Coarse live root biomass

CNC

C/N ratio in coarse live roots

CNF

C/N ratio of fast soil carbon pool

CNL

Potential cumulative nitrogen loss

CNP

Cumulative nitrogen input

CNR

C/N ratio in five live roots

CNS

C/N ratio of slow soil carbon pool

CUM

Cumulative soil carbon sequestration

DEP

Annual atmospheric nitrogen deposition

FAF

Fraction of belowground biomass production allocated to fine live roots

FAR

Fraction of aboveground biomass removed during harvest (harvest efficiency)

FCL

Annual coarse live root mortality

FDC

Annual loss of fast soil carbon via decomposition

FFL

Annual fine live root mortality

FFR

Fertilization factor used to scale APP to AAP

FLR

Fine live root biomass

FLS

Fractional annual transfer of surface litter carbon to fast soil carbon

FNF

Fraction of initial soil carbon in the fast soil carbon pool

FSC

Fast soil carbon stock

HRV

Harvested aboveground biomass

IFC

Annual carbon transfer from coarse live roots to fast soil carbon

IFF

Annual carbon transfer from fine live roots to fast soil carbon

LDC

Annual loss of surface litter carbon via decomposition

LFS

Annual transfer of surface litter carbon to fast soil carbon

LRB

Total live belowground biomass

LSC

Surface litter carbon stock

MAT

Mean annual air temperature

NFR

Annual nitrogen fertilization

NLS

Potential annual nitrogen loss

NMR

Annual rate of net soil nitrogen mineralization

NNM

Annual net soil nitrogen mineralization

NUE

Nitrogen use efficiency

NUP

Annual plant nitrogen uptake from available soil nitrogen

RBA

Ratio of annual belowground-to-aboveground biomass production

RFF

Nitrogen translocation

RHC

Heterotrophic soil respiration

RSR

Root-to-shoot biomass ratio

SCS

Saturation limit for the slow soil carbon pool

SDC

Annual loss of slow soil carbon via decomposition

SNS

Soil nitrogen stock

SOC

Carbon stock in the mineral soil (excluding LSC)

SSC

Slow soil carbon stock

STB

Annual flux of carbon from fast soil carbon to slow soil carbon

STR

Annual transfer rate for carbon flux from fast soil carbon to slow soil carbon

TCL

Annual production of coarse live roots

TCR

Turnover time of coarse live roots

TFL

Annual production of fine live roots

TFR

Turnover time of fine live roots

TFS

Turnover time of fast soil carbon

TLC

Annual carbon inputs to surface litter

TLS

Turnover time of surface litter carbon

TSS

Turnover time of slow soil carbon

Notes

Acknowledgments

This research was sponsored by the US Department of Energy’s Office of Science, Biological and Environmental Research funding to the Consortium for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems, and performed at Oak Ridge National Laboratory (ORNL). ORNL is managed by UT-Battelle, LLC, for the US Department of Energy under contract DE-AC05-00OR22725. I wish to thank Stan Wullschleger (ORNL) and Mac Post (ORNL) for their helpful reviews of the draft manuscript.

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Copyright information

© Springer Science+Business Media, LLC. (outside the USA)  2011

Authors and Affiliations

  1. 1.Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeUSA

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