LSU AgCenter releases sweet sorghum production guide

By Louisiana State University | October 23, 2014

Sweet sorghum is not currently grown as a commercial crop in Louisiana, but in the future, producers may consider growing it for use as a biofuel feedstock.

To help guide commercial production of this crop, the Louisiana State University AgCenter has released the Sweet Sorghum Production Guide.

The guide was written to supply producers with information they will need to grow profitable sweet sorghum crops, said LSU AgCenter crops specialist Wink Alison.

“Sweet sorghum has been found to be a potential biofuel crop,” Alison said. “We want to show people sweet sorghum can be grown in Louisiana and what they need to do to be successful at it.”

Sweet sorghum has been chosen as a potential feedstock for biofuel because it produces both fiber and sugars using relatively modest agricultural inputs when grown on marginal soils, said Sonny Viator, coordinator of the LSU AgCenter Iberia Research Station.

AgCenter researchers are studying how to produce sweet sorghum, as well as energycane, for use as feedstocks for biofuels as part of its Sustainable Bioproducts Initiative. The study focuses on evaluating geographic zones for adaptation, producing commercial yields on marginal soils and determining low-input sustainable production practices.

Sweet sorghum can be grown throughout Louisiana, and some of the findings of this study are available in the Sweet Sorghum Production Guide.

“Several years of research under Louisiana’s climatic conditions have found that both biomass and fermentable sugar yields vary widely depending on growing conditions and maturity of the varieties/hybrids being evaluated,” Viator said.

“Varieties and hybrids of medium maturity planted during the optimum time of mid-April to mid-May have consistently produced impressive yields, whereas early-maturing varieties and hybrids produce less biomass, especially when planted outside the optimal planting date period,” he said.

Sustaining feedstock deliveries for a three-month processing period requires a range of maturity groups, Viator said. Price structure will depend on product demand and will have to exceed cost of production and be competitive with existing commodity prices.

Sweet sorghum is not grown for biofuel use in the United States, but researchers say they believe one day it will be grown throughout the country, with most of the crop concentrated in the Southeast.

Today, sweet sorghum in Louisiana is grown in small plots and used for niche market items such as syrups.

“South America, especially Brazil, has been growing sweet sorghum as a complementary crop with sugarcane for several years,” Viator said. “It has not reached commercialization in the U.S. as of yet. But there are pilot programs, and growing sweet sorghum for commercial use may be just around the corner.”

The AgCenter production guide is a compilation of what researchers have found during the study. The guide includes information on planting, fertilizing, varieties, harvesting, processing and economics. Equipment used to plant sweet sorghum is also addressed in the guide.

“We’ve found sweet sorghum can fit into a row-crop production system,” Alison said. “Producers don’t need special equipment to grow it. And it can be profitable.”

Sweet sorghum is an annual plant, with seed similar to that of grain sorghum, Alison said. “So the same planting equipment can be used for both grain sorghum and sweet sorghum.”

Researchers have evaluated available varieties and identified several for Louisiana producers to grow for the biofuels industry. They are Dale, M81E, Theis and Topper 76-6. Recently, commercial companies have released new hybrids, some of which have been evaluated in Louisiana.

In addition to planting information, the production guide contains harvest information.

AgCenter researchers have found producers can use existing harvest equipment. But because whole-plant harvest is necessary for use in the biofuels industry, billet harvesters used with sugarcane also can be used for sweet sorghum. Researchers are studying the harvest efficiency of using sugarcane combine harvesters as well.

Harvested sweet sorghum must be brought to a processing facility where the juice and plant fibers are separated and then processed for use in the biofuels industry.

“Sweet sorghum, like energycane, contains simple sugars and complex sugars,” said Donal Day of the LSU AgCenter Audubon Sugar Institute. “The complex sugars can be converted to simple sugars. Fuels can be produced from the sugars either directly, using catalytic methods, or by fermentation.”

Sweet sorghum is an annual crop, which means it must be planted every year. This is something AgCenter plant researcher Kun-Jun Han said he believes will be attractive to Louisiana producers.

“Because sweet sorghum is an annual crop, producers can easily change their management strategy, depending on imminent market conditions,” Han said. “There’s no long-term commitment like there is for sugarcane. If another crop is more profitable in one year than sweet sorghum, producers can switch from growing sweet sorghum to the crop that is more profitable.”

In addition to information on planting, harvesting and processing sweet sorghum for use in biofuels, the Sweet Sorghum Production Guide also addresses the economics of growing sweet sorghum, including costs associated with land preparation and transportation.

While AgCenter researchers are preparing for the biofuels industry to become big business in Louisiana and the need for sweet sorghum to increase, they also said producers may want to wait before putting too much money and time into growing this crop.

“Right now, there’s just not a market for sweet sorghum to use for biofuels in Louisiana,” Alison said. “Until there’s an industry for it, sweet sorghum is not a crop someone will grow. But when the biofuels industry does come to Louisiana, we’ll be ready for it. We’ll know what to do to help producers grow profitable crops.”

The Sustainable Bioproducts Initiative project involves a team of university and industry partners, led by the LSU AgCenter, studying the regular production of biomass for economically viable conversion to biofuels and bioenergy using existing refinery infrastructure.

The project is funded through a $17.2 million grant from the United States Department of Agriculture’s Agriculture and Food Research Initiative. For more information on the SUBI project, go to www.lsuagcenter.com/subi