Soil Carbon Storage by Switchgrass Grown for Bioenergy

Life-cycle assessments (LCAs) of switchgrass (Panicum virgatum L.) grown for bioenergy production require data on soil organic carbon (SOC) change and harvested C yields to accurately estimate net greenhouse gas (GHG) emissions. To date, nearly all information on SOC change under switchgrass has been based on modeled assumptions or small plot research, both of which do not take into account spatial variability within or across sites for an agro-ecoregion. To address this need, we measured change in SOC and harvested C yield for switchgrass fields on ten farms in the central and northern Great Plains, USA (930 km latitudinal range). Change in SOC was determined by collecting multiple soil samples in transects across the fields prior to planting switchgrass and again 5 years later after switchgrass had been grown and managed as a bioenergy crop. Harvested aboveground C averaged 2.5 ± 0.7 Mg C ha−1 over the 5 year study. Across sites, SOC increased significantly at 0–30 cm (P = 0.03) and 0–120 cm (P = 0.07), with accrual rates of 1.1 and 2.9 Mg C ha−1 year−1 (4.0 and 10.6 Mg CO2 ha−1 year−1), respectively. Change in SOC across sites varied considerably, however, ranging from −0.6 to 4.3 Mg C ha−1 year−1 for the 0–30 cm depth. Such variation in SOC change must be taken into consideration in LCAs. Net GHG emissions from bioenergy crops vary in space and time. Such variation, coupled with an increased reliance on agriculture for energy production, underscores the need for long-term environmental monitoring sites in major agro-ecoregions.

[1]  J. E. Weaver,et al.  Amounts of underground plant materials in different grassland climates , 1939 .

[2]  J. E. Weaver,et al.  LENGTH OF LIFE OF ROOTS OF TEN SPECIES OF PERENNIAL RANGE AND PASTURE GRASSES. , 1946, Plant physiology.

[3]  J. E. Weaver Prairie Plants and Their Environment: A Fifty-year Study in the Midwest , 1968 .

[4]  C. Jones,et al.  Effect of Soil Texture on Critical Bulk Densities for Root Growth , 1983 .

[5]  D. F. Cox,et al.  Statistical Procedures for Agricultural Research. , 1984 .

[6]  R. Westerman Soil testing and plant analysis , 1990 .

[7]  John S. Shenk,et al.  Population Definition, Sample Selection, and Calibration Procedures for Near Infrared Reflectance Spectroscopy , 1991 .

[8]  Brian W Ilbery,et al.  Agricultural Research Alternatives , 1993 .

[9]  R. Littell SAS System for Mixed Models , 1996 .

[10]  Marie E. Walsh,et al.  U.S. bioenergy crop economic analyses: status and needs. , 1998 .

[11]  Stan D. Wullschleger,et al.  Soil carbon dynamics beneath switchgrass as indicated by stable isotope analysis. , 2000 .

[12]  James W. Fyles,et al.  Carbon sequestration in perennial bioenergy, annual corn and uncultivated systems in southern Quebec , 2001 .

[13]  Rattan Lal,et al.  Soil Carbon Sequestration and the Greenhouse Effect , 2001 .

[14]  F. Nachtergaele Soil taxonomy—a basic system of soil classification for making and interpreting soil surveys: Second edition, by Soil Survey Staff, 1999, USDA–NRCS, Agriculture Handbook number 436, Hardbound , 2001 .

[15]  V. R. Tolbert,et al.  High-value renewable energy from prairie grasses. , 2002, Environmental science & technology.

[16]  K. Bowren,et al.  Potential of forages to diversify cropping systems in the Northern Great Plains , 2002 .

[17]  Alan J. Franzluebbers,et al.  Soil organic matter stratification ratio as an indicator of soil quality , 2002 .

[18]  D. Andress,et al.  Soil carbon changes for bioenergy crops. , 2004 .

[19]  Mark A. Liebig,et al.  Biomass and carbon partitioning in switchgrass. , 2004 .

[20]  D. M. Temple,et al.  Erosion processes in gullies modified by establishing grass hedges , 2004 .

[21]  Jack A. Morgan,et al.  Greenhouse gas contributions and mitigation potential of agricultural practices in northwestern USA and western Canada , 2005 .

[22]  J. D. Hanson,et al.  Germination of switchgrass under various temperature and pH regimes. , 2005 .

[23]  Mark A. Liebig,et al.  Soil carbon under switchgrass stands and cultivated cropland , 2005 .

[24]  Bruce Anderson,et al.  Renovating Pastures with Glyphosate Tolerant Soybeans , 2005 .

[25]  J. Krupinsky,et al.  Biomass Yield, Phenology, and Survival of Diverse Switchgrass Cultivars and Experimental Strains in Western North Dakota , 2005 .

[26]  S. Polasky,et al.  Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[27]  M. Liebig,et al.  Soil response to long-term grazing in the northern Great Plains of North America , 2006 .

[28]  Kent M. Eskridge,et al.  Establishment Stand Thresholds for Switchgrass Grown as a Bioenergy Crop , 2006 .

[29]  J. T. Green,et al.  Long-term yield potential of switchgrass-for-biofuel systems. , 2006 .

[30]  May Wu,et al.  Energy and Emission Benefits of Alternative Transportation Liquid Fuels Derived from Switchgrass: A Fuel Life Cycle Assessment , 2006, Biotechnology progress.

[31]  B. McConkey,et al.  Cropping system influences on soil chemical properties and soil quality in the Great Plains , 2006, Renewable Agriculture and Food Systems.

[32]  D. Tilman,et al.  Carbon-Negative Biofuels from Low-Input High-Diversity Grassland Biomass , 2006, Science.

[33]  Eugene F. Kelly,et al.  LTER : Long Term Ecological Research Network , 2007 .

[34]  W. Parton,et al.  Life-cycle assessment of net greenhouse-gas flux for bioenergy cropping systems. , 2007, Ecological applications : a publication of the Ecological Society of America.

[35]  Vance N. Owens,et al.  Switchgrass and Soil Carbon Sequestration Response to Ammonium Nitrate, Manure, and Harvest Frequency on Conservation Reserve Program Land , 2007 .

[36]  S. Polasky,et al.  Land Clearing and the Biofuel Carbon Debt , 2008, Science.

[37]  Jacinto F. Fabiosa,et al.  Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land-Use Change , 2008, Science.

[38]  R. Perrin,et al.  Net energy of cellulosic ethanol from switchgrass , 2008, Proceedings of the National Academy of Sciences.

[39]  R. Perrin,et al.  Farm-Scale Production Cost of Switchgrass for Biomass , 2008, BioEnergy Research.

[40]  William F. Laurance,et al.  How Green Are Biofuels? , 2008, Science.

[41]  John H. Porter,et al.  A Brief History of Data Sharing in the U.S. Long Term Ecological Research Network , 2010 .

[42]  Donald L. Suarez,et al.  Carbonate and Gypsum , 2018, SSSA Book Series.

[43]  R. L. Westerman,et al.  Analytical Instruments for Soil and Plant Analysis , 2018, SSSA Book Series.

[44]  K. H. Hartge,et al.  Bulk Density , 2018, SSSA Book Series.