Publication : USDA ARS (original) (raw)

Title: SOIL CARBON UNDER SWITCHGRASS STANDS AND CULTIVATED CROPLAND

Author

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/8/2004
Publication Date: 4/1/2005
Citation: Liebig, M.A., Johnson, H.A., Hanson, J.D., Frank, A.B. 2005. Soil carbon under switchgrass stands and cultivated cropland. Biomass and Bioenergy 28(4):347-354.

Interpretive Summary: Concerns regarding negative social and environmental consequences of a fossil fuel-based economy have increased interest in developing a bioenergy industry in the USA. Switchgrass is considered to be a valuable bioenergy crop with significant potential to sequester soil organic carbon (SOC). A study was conducted to evaluate soil carbon stocks within established switchgrass stands and nearby cultivated cropland on farms throughout the northern Great Plains and northern Cornbelt. Soil from forty-two paired switchgrass/cropland sites throughout MN, ND, and SD were sampled to a depth of approximately 4 feet and analyzed for soil carbon. Soil organic carbon was greater in switchgrass stands than cultivated cropland at soil depths of 0 to 2, 12 to 24, and 24 to 36 inches. Differences in SOC between switchgrass stands and cultivated cropland were especially pronounced at deeper soil depths, where treatment differences were 7.74 and 4.35 Mg/ha (or 6900 lbs/ac and 3900 lbs/ac) for the 12 to 24 and 24 to 36 inch depths, respectively. Greater root biomass below the 12 inch soil depth in switchgrass likely contributed to trends in SOC between switchgrass stands and cultivated cropland. Switchgrass appears to be effective at storing SOC not just near the soil surface, but also at depths below 12 inches where carbon is less susceptible to loss.

Technical Abstract: Switchgrass (Panicum virgatum L.) is considered to be a valuable bioenergy crop with significant potential to sequester soil organic carbon (SOC). A study was conducted to evaluate soil carbon stocks within established switchgrass stands and nearby cultivated cropland on farms throughout the northern Great Plains and northern Cornbelt. Soil from forty-two paired switchgrass/cropland sites throughout MN, ND, and SD were sampled to a depth of 1.2 m and analyzed for soil carbon in depth increments of 0 to 0.05, 0.05 to 0.1, 0.1 to 0.2, 0.2 to 0.3, 0.3 to 0.6, 0.6 to 0.9, and 0.9 to 1.2 m. Soil organic carbon was greater (P<0.1) in switchgrass stands than cultivated cropland at 0 to 0.05, 0.3 to 0.6, and 0.6 to 0.9 m. Differences in SOC between switchgrass stands and cultivated cropland were especially pronounced at deeper soil depths, where treatment differences were 7.74 and 4.35 Mg/ha for the 0.3 to 0.6 and 0.6 to 0.9 m depths, respectively. Greater root biomass below 0.3 m in switchgrass likely contributed to trends in SOC between switchgrass stands and cultivated cropland. Switchgrass appears to be effective at storing SOC not just near the soil surface, but also at depths below 0.3 m where carbon is less susceptible to mineralization and loss.