recent ruling by the U.S. Environmental Protection Agency says 288 million gallons of cellulosic biofuel must be blended into the U.S. gasoline supply this year, down slightly from last year.
Until now, producers have relied on incomplete information and unrealistic, small-scale studies in guiding decisions about which feedstocks to grow and where, but a new multi-institution report provides practical agronomic data for five cellulosic feedstocks, which would improve adoption and increase production across the country.
"Our main goal with this project was to determine whether these species could be viable crops when grown on the farm scale," said D.K. Lee, associate professor in the Department of Crop Sciences at the University of Illinois and leader of the prairie mixture portion of the study.
The project, backed by the U.S. Department of Energy and the Sun Grant Initiative, began in 2008 and includes researchers from 26 institutions. Together, they evaluated the bioenergy potential of switchgrass, miscanthus, sorghum, energycane and prairie mixtures in long-term trials spanning a wide geographical area.
Crops were grown for five to seven years in multiple locations and with varying levels of nitrogen fertilizer. Although most of the crops are known to tolerate poor soil quality, the researchers found that they all benefited from at least some nitrogen. And although most of the crops are somewhat drought-tolerant, precipitation made a difference.
The new results said the greatest yield potentials for lowland switchgrass varieties are in the lower Mississippi valley and the Gulf Coast states, whereas miscanthus and prairie mixture yields are likely to be greatest in the upper Midwest. Energycane could reach high yields but in a relatively limited portion of the country. The crop that shows the highest potential yields in the greatest number of locations is sorghum.
"In terms of management, sorghum is almost the same as corn. It germinates and grows so quickly, weed control is not a big issue. If you plant by early June, it will be 15 to 20 feet tall by September. It also has good drought tolerance," Lee said.
But sorghum is wet at harvest and can't be stored. It also requires nitrogen and can lodge, or collapse, before harvest in wet or windy conditions.
Racehorse vs. workhorse
Is it better to choose a sweet corn hybrid with exceptional yields under ideal growing conditions, the racehorse, or one that performs consistently well across ideal and less-than-ideal conditions, the workhorse?
New research from the University of Illinois suggests the workhorse is the winner in processing sweet corn.
In processing sweet corn, vegetable processors -- not growers -- choose the hybrid for each field. Processors need hybrids that lend themselves to machine harvest, ears that hold up to processing and kernels that maintain quality as a finished product.
"When sweet corn is ripe, it must be harvested. Unlike grain corn, which can be storied prior to use, sweet corn must be processed and preserved immediately after harvest," said Marty Williams, an ecologist with U of I's Department of Crop Sciences and USDA-ARS. "Midwest processors want to have their plants running at capacity throughout the approximately three-month harvest window. A plant running significantly above or below that capacity is costly. I suspect a racehorse hybrid is problematic because it's difficult to predict its performance when the weather deviates from ideal growing conditions, which is common in the Midwest."
Evidence that vegetable processors prioritize stability could inform future sweet corn breeding programs, and it would provide a sense of security for growers. "Growers are more likely tasked with growing a workhorse over a racehorse. That decision buffers them, as well as the processor, from less-than-ideal growing conditions," Williams said.