 Now, however, it appears that maize itself may prove to be the
ultimate U.S. biofuels crop. Early research results show that
tropical maize, when grown in the Midwest, requires few crop
inputs such as nitrogen fertilizer, chiefly because it does not
produce any ears. It also is easier for farmers to integrate
into their current operations than some other dedicated energy
crops because it can be easily rotated with corn or soybeans,
and it can be planted, cultivated and harvested with the same
equipment U.S. farmers already have. Finally, tropical maize
stalks are believed to require less processing than corn grain,
corn stover, switchgrass, Miscanthus giganteus and the scores of
other plants now being studied for biofuel production.What it
does produce, straight from the field with no processing, is 25
percent or more sugar in the forms of sucrose, fructose and
glucose.
"Corn is a short-day plant, so when we grow tropical maize
here in the Midwest, the long summer days delay flowering, which
causes the plant to grow very tall and produce few or no ears,"
says Below. Without ears, these plants concentrate sugars in
their stalks, he adds. Those sugars could have a dramatic affect
on Midwestern production of ethanol and other biofuels.
According to Below, "Midwestern-grown tropical maize easily
grows 14 or 15 feet tall compared to the 7 1/2-feet height that
is average for conventional hybrid corn. It's all in these tall
stalks. In our early trials, we are finding that these plants
build up to a level of 25 percent or higher of sugar in their
stalks."
This differs from conventional corn and other crops being
grown for biofuels in that the starch found in corn grain and
the cellulose in switchgrass, corn stover and other biofuel
crops must be treated with enzymes to convert them into sugars
that can be then fermented into alcohols such as ethanol.
Storing simple sugars also is more cost-effective for the
plant, because it takes a lot of energy to make the complex
starches, proteins and oils present in corn grain. This energy
savings per plant could result in more total energy per acre
with topical maize, since it produces no grain.
"In terms of biofuel production, tropical maize could be
considered the 'sugar cane of the Midwest,'" Below said. "The
tropical maize we're growing here at the University of Illinois
is very lush, very tall and very full of sugar." He added that
his early trials also show that tropical maize requires much
less nitrogen fertilizer than conventional corn and that the
stalks actually accumulate more sugar when less nitrogen is
available. Nitrogen fertilizer is one of major costs of growing
corn.
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He explained that sugar cane used in Brazil to make ethanol is
desirable for the same reason: It produces lots of sugar without a
high requirement for nitrogen fertilizer, and this sugar can be
fermented to alcohol without the middle steps required by
high-starch and cellulosic crops. But sugar cane can't be grown in
the Midwest.
The tall stalks of tropical maize are so full of sugar that
producers growing it for biofuel production will be able to supply a
raw material at least one step closer to being turned into fuel than
are ears of corn.
"And growing tropical maize doesn't break the farmers' rotation.
You can grow tropical maize for one year and then go back to
conventional corn or soybeans in subsequent years," Below said. "Miscanthus,
on the other hand, is thought to need a three-year growth cycle
between initial planting and harvest, and then your land is in
Miscanthus. To return to planting corn or soybean necessitates
removing the Miscanthus rhizomes.
Professor Below is studying topical maize with doctoral candidate
Mike Vincent and postdoctoral research associate Matias Ruffo and in
conjunction with U of I Associate Professor Stephen Moose. This
latest discovery of high sugar yields from tropical maize became
apparent through cooperative work between Below and Moose to
characterize genetic variation in response to nitrogen fertilizers.
Currently supported by the National Science Foundation, these
studies are a key element to developing maize hybrids with improved
nitrogen use efficiency. Both Below and Moose are members of
Illinois
Maize Breeding and Genetics Laboratory, which has a long history
of conducting research that identifies new uses for the maize crop.
Moose now directs the longest-running plant genetics experiment
in the world, in which more than a century of selective breeding has
been applied to alter carbon and nitrogen accumulation in the maize
plant. Continued collaboration between Below and Moose will
investigate whether materials from these long-term selection
experiments will further enhance sugar yields from tropical maize.
[Text from file received from
the University of Illinois
College of Agricultural, Consumer and Environmental Sciences]
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