According to research conducted by Fred Below at the University of Illinois (U of I), maize may prove to be the ultimate U.S. biofuels crop. This comes at somewhat of a surprise, because U of I has been studying and advocating Miscanthus for some time.
The chief advantage of maize, when grown in the Midwest, is that it requires much less nitrogen fertilizer input than corn because it does not produce any ears. The sugar is in the stalks, not in the ears and is in the form of sucrose, fructose and glucose.
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.
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 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.
"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." Below explains. "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.
In terms of biofuel production, tropical maize could be considered the 'Sugarcane 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.
Sugarcane produced in Brazil has the same attributes: 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 sugarcane can't be grown in the Midwest.
"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."
The reduction in the use of nitrogen and enzymes certainly would have a significant effect on reducing the cost of ethanol. Also, there has to be some cellulose in maize, which if extracted, would further increase the yield. It sounds like it would be an easy transition to cellulosic ethanol when cost effective enzymes become available.
It sounds like their is a little friendly competition going on at U of I between the advocates of Miscanthus and Maize. Even if Miscanthus turns out to be better it has limitations today in that it cannot be propagated easily and the enzymes for cellulosic ethanol have not been proven to be economical yet.
This post is based on material furnished by the University of Illinois.