A. Denise Attaway
Researchers with the LSU AgCenter, Mississippi State University Cooperative Extension Service and the U.S. Department of Agriculture are working together to bring the high biomass version of sugarcane, known as energycane, and sweet sorghum way north of Interstate 10, which runs east and west across south Louisiana.
“We’re looking at these as crops producers can grow in addition to crops they’re already growing,” said Donal Day, project manager for the LSU AgCenter’s Sustainable Bioproducts Initiative. “We’re looking at how producers in the northern areas of Louisiana and Mississippi can grow these crops to help supplement their incomes.”
Both crops can be used to provide feedstock for biorefineries to use in producing biofuels.
Brian Baldwin, a professor of plant and soil science at Mississippi State, said energycane is a hybrid of sugarcane and wild cane bred for high fiber – or high biomass.
The researchers are testing five types of energycane at locations in Tifton, Ga., Athens, Ga., Starkville, Miss., Raymond, Miss., St. Gabriel, La., College Station, Texas, Beaumont, Texas, and Waimanalo, Hawaii.
“Yes, we’re testing energycane in Hawaii,” Baldwin said. “The coastal areas are rapidly being converted to housing. The only place for agriculture to grow is farther up the mountains, and those areas can get cold.”
Researchers at the USDA-Agricultural Research Service Sugarcane Research Unit in Houma, La., are crossbreeding sugarcane with miscanthus, commonly known as elephant grass, and two ancestral species of sugarcane to produce a number of different energycane varieties that can be grown in colder temperatures.
“Creating an energycane variety that is cold-tolerant will extend the range of cultivation and allow for producers outside the traditional cane growing areas to produce energycane crops,” said Collins Kimbeng, a plant breeder with the LSU AgCenter. “Creating cold-tolerant varieties also will allow for energycane to be grown later in the winter months, prolonging the growing season and enabling producers to produce crops for longer periods of time.”
In addition to creating a new breed of cane, researchers also are studying management practices for growing energycane in colder temperatures. LSU AgCenter sugarcane specialist Kenneth Gravois said these practices include fertility management and planting depths and, farther north, row spacing.
“Our goal is to produce an energycane crop with minimal inputs, such as reduced nitrogen rates and reduced cultivation,” Gravois said.
Researchers also are studying sweet sorghum as another feedstock. According to Sonny Viator, an LSU AgCenter professor and resident coordinator of the Iberia Research Station, sweet sorghum has been identified as a high-producing sugar crop that creates juice that can be used to make biofuels and biochemicals.
Just as the fiber in energycane is used to produce biofuels, the juice in sweet sorghum is used to make butanol, ethanol and other products.
Sweet sorghum “is a low-input crop, one that can be grown on marginal soil, and a crop suitable for sustainable production,” Viator said. “And we’ve identified it as one of the sugar crops that can be used to produce biofuels.”
The researchers are trying to determine the potential for producing sweet sorghum from midsummer to the first frost by varying the timing of planting and using plants of different maturity levels. That combination of planting dates and differing maturities allows the sorghum to be available for harvest over a sustained period of about three months.
Traditionally, the best planting period for sweet sorghum in Louisiana has been from mid-April to mid-May, with harvest in August. This study is looking at a production model of harvesting sweet sorghum beginning in July and extending until early November. Following that, energycane would be harvested until spring, when, perhaps, a third crop would be available.
“The ultimate goal is to supply feedstock to a biorefinery for most of the year,” Viator said.
A trio of LSU AgCenter researchers is investigating sweet sorghum sustainable production practices at AgCenter research stations across the state. Wink Alison at the AgCenter Scott Research and Extension Center in Winnsboro, La., Kun-Jun Han in the School of Plant, Environmental and Soil Sciences in Baton Rouge, and Dustin Harrell at the AgCenter Rice Research Station in Crowley, La., are identifying production practices that can help producers optimize yields.
When the project is completed, producers should know how much fertilizer to apply and how much tillage is required and understand the benefits of using legumes in rotation with sweet sorghum.
LSU AgCenter forestry specialist Michael Blazier at the Hill Farm Research Station in Homer, La., is conducting a carbon sequestration study in tandem with the research on fertilizing sweet sorghum and growing energycane north of its typical growing area.
Blazier’s study measures the carbon content of soils to a 3-foot depth and the organic matter residues left after harvest. In addition, the study involves measuring soil microbial biomass activity and functional diversity.
“We’re measuring the soil microbial parameters because soil microbes are essential for converting organic matter into nutrients needed for crop growth,” Blazier said. “With the microbial information, we’ll understand how well organic residues are recycled as nutrients, which can be helpful for Louisiana producers in making decisions about fertilizer sources for sweet sorghum and residue retention for sugarcane.”
The soil and organic matter carbon information the researchers are collecting will be used to determine the extent to which producing biofuels from sweet sorghum and sugarcane takes carbon dioxide from the atmosphere and stores it long-term in the soil.
“This is an important component of being able to enter the biofuels market because those markets are heavily influenced by domestic and international government programs and mandates to offset conventional fuel use with biofuels that take up more carbon dioxide from the atmosphere than emitted in their production and use,” Blazier said.
After the energycane and sweet sorghum have been harvested, the crops can be brought to a processing plant to produce juice, syrup and bagasse for use in the biofuels industry. As part of the Sustainable Bioproducts Initiative, the LSU AgCenter has constructed a pilot plant at the Audubon Sugar Institute in St. Gabriel, La.
Energycane and sweet sorghum are converted into biofuels using several different processes, such as the Optinol Process. This process comes from an industry partner on the project, Optinol, and uses a patented bacterium that naturally favors the production of butanol while producing virtually no acetone or ethanol.
Another process developed by industry partner Virent converts fermentable sugars into jet fuel.
According to Day, plants similar to the AgCenter’s pilot plant can be strategically placed so that they are located near energycane and sweet sorghum production for use as biofuel feedstock.
“Producers would greatly benefit from having a plant such as this nearby,” Day said. “We would be happy to meet with anyone interested in growing these crops or building one of these plants. This would be a great venture for producers living in the Delta.”
A. Denise Attaway is an assistant communications specialist with the LSU AgCenter Sustainable Bioproducts Initiative.
(This article was published in the 2014 winter issue of Louisiana Agriculture magazine.)