The researchers analyzed data from dozens of studies to determine
how planting new biofuel crops can influence the carbon content of the
Plants use the sun's energy to convert carbon dioxide from the
atmosphere into the organic carbon that makes up leaves, stems and
other plant parts. As plants decay, this carbon goes into the soil.
Organic carbon is an important component of soil health and also
influences atmospheric carbon dioxide levels. Whenever the soil is
disturbed, as occurs when land is plowed or cleared of vegetation, some
of this carbon returns to the atmosphere in the form of carbon dioxide.
Unlike corn, which must be replanted every year, perennial grasses
such as switchgrass and Miscanthus preserve and increase carbon stores
in the soil. These and other grasses have been proposed as high-energy
alternative feedstocks for biofuel production.
These findings appear in December 2008 in the journal Global Change Biology Bioenergy.