title: Energy potential and greenhouse gas emissions from bioenergy cropping systems on marginally productive cropland.
abstract: Low-carbon biofuel sources are being developed and evaluated in the United States and Europe to partially offset petroleum transport fuels. Current and potential biofuel production systems were evaluated from a long-term continuous no-tillage corn (Zea mays L.) and switchgrass (Panicum virgatum L.) field trial under differing harvest strategies and nitrogen (N) fertilizer intensities to determine overall environmental sustainability. Corn and switchgrass grown for bioenergy resulted in near-term net greenhouse gas (GHG) reductions of -29 to -396 grams of CO2 equivalent emissions per megajoule of ethanol per year as a result of direct soil carbon sequestration and from the adoption of integrated biofuel conversion pathways. Management practices in switchgrass and corn resulted in large variation in petroleum offset potential. Switchgrass, using best management practices produced 3919±117 liters of ethanol per hectare and had 74±2.2 gigajoules of petroleum offsets per hectare which was similar to intensified corn systems (grain and 50% residue harvest under optimal N rates). Co-locating and integrating cellulosic biorefineries with existing dry mill corn grain ethanol facilities improved net energy yields (GJ ha-1) of corn grain ethanol by >70%. A multi-feedstock, landscape approach coupled with an integrated biorefinery would be a viable option to meet growing renewable transportation fuel demands while improving the energy efficiency of first generation biofuels.
authors.affiliation: Agroecosystem Management Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Lincoln, Nebraska, United States of America.
authors.forename: Marty R
authors.initials: MR
authors.lastname: Schmer
authors.affiliation: Grain, Forage and Bioenergy Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Lincoln, Nebraska, United States of America.
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Vogel
authors.affiliation: Agroecosystem Management Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Lincoln, Nebraska, United States of America.
authors.forename: Gary E
authors.initials: GE
authors.lastname: Varvel
authors.affiliation: Soil-Plant Nutrient Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Ft. Collins, Colorado, United States of America.
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Follett
authors.affiliation: Grain, Forage and Bioenergy Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Lincoln, Nebraska, United States of America.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Mitchell
authors.affiliation: Agroecosystem Management Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Lincoln, Nebraska, United States of America.
authors.forename: Virginia L
authors.initials: VL
authors.lastname: Jin
mesh_terms: D056804:Biofuels; D018556:Crops, Agricultural / Q000187:drug effects / Q000254:growth & development*; D005740:Gases / Q000032:analysis*; D017752:Greenhouse Effect; D009584:Nitrogen / Q000494:pharmacology; D008897:Panicum / Q000187:drug effects / Q000254:growth & development; D003313:Zea mays / Q000187:drug effects / Q000254:growth & development
chemical_list: D056804:Biofuels; D005740:Gases; D009584:Nitrogen