If Corn Is Biofuels King, Tropical Maize May Be Emperor
In terms of biofuel production, tropical maize could be the sugarcane of the Midwest. Its tall stalks are so full of sugar that it is at least one step closer to being turned into fuel than are ears of corn, according to University of Illinois research.
Maize may prove to be the ultimate U.S. biofuels crop. It produces 25% or more sugar as sucrose, fructose and glucose. This sugar is one step closer to becoming ethanol than the starch in corn, miscanthus, stover and switchgrass. These conventional feedstocks must be treated with enzymes to convert them into sugars that can be then fermented into 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 in corn grain. This energy savings per plant could result in more total energy per acre with topical maize, since it produces no grain.
When University of Illinois crop scientist Fred Below began growing tropical maize, the form of corn grown in the tropics, he was looking for novel genes for nitrogen utilization. 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 can be easily integrated into farmers' 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 existing equipment.
“Corn is a short-day plant, so when we grow tropical maize 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. According to Below, Midwestern-grown tropical maize easily grows 14-15 ft. tall building up to a level of at least 25% sugar in its stalks.
The tropical maize at the University of Illinois requires much less nitrogen fertilizer than conventional corn, and the stalks actually accumulate more sugar when less nitrogen is available.
Below explained that sugarcane 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 sugarcane 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 farmers' rotation,”Below says.