WASHINGTON, June 18, 2014 - Researchers at Texas A&M University say that in addition to being another source of energy, sorghum grown to make biofuel also may offer a significant source of carbon sequestration.
Sorghum still represents a relatively small share of the biofuel feedstock market, but is interchangeable with corn in the grain-based ethanol market (a bushel of grain sorghum produces as much ethanol as a bushel of corn). Approximately a third of the U.S. sorghum crop – almost 390 million bushels in 2013 is used for biofuel production.
Naturally drought-tolerant – last year’s crop represented a nearly 60-percent increase over the 2012 harvest, a rise attributable to its hardiness during the ongoing drought sorghum can be used for many different types of ethanol production, including starch-based, sugar-based and cellulosic ethanol production.
Members of the Texas A&M’s soil and crop sciences department are measuring greenhouse gases from biofuel production scenarios to help quantify the carbon footprint of a bioenergy cropping system, as well as evaluate compliance with federally mandated reduction goals.
Frank Hons, professor of soil science, says the study, “Impacts of Biomass Sorghum Feedstock Production on Carbon Sequestration and Greenhouse Gas Emissions,” indicates that bioenergy sorghum may play an even more significant role in future biofuel production as a high quality biomass feedstock. The study was funded by Texas A&M’s AgriLife Research Cropping Systems bioenergy program and a grant from USDA’s National Institute of Food and Agriculture.
To date, no previous studies have quantified life cycle greenhouse gases from sorghum grown as a fuel feedstock.
“Bioenergy crop production represents an opportunity for greenhouse gas mitigation in the U.S.,” said Hons. “Crop production systems can be a net sink or net source of atmospheric carbon dioxide, depending on a number of factors, including land management practices.”
Another member of the research team, Joe Storlien, a postdoctoral research associate, said life cycle analyses are used to evaluate biofuel efficiency by balancing the direct and indirect greenhouse gases associated with production with the total energy output and soil carbon storage.
One objective of the study was to determine the effects of crop rotation, nitrogen fertilization and residue management on net greenhouse gas emissions from bioenergy sorghum production. The study, conducted on a field under bioenergy sorghum production since 2008, analyzed direct and indirect greenhouse emissions, soil carbon sequestration to a three-foot depth, and theoretical biofuel yield from eight different bioenergy sorghum production scenarios.
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