Switchgrass: Two Decades of Progress

Author: 
Jake Miller
Newsletter Issue: 
October 2015

Dr. Michael Casler cutting grasses in the field
Above: Dr. Michael Casler, Plant Breeder USDA ARS in his switchgrasss research test plots. 
Photo credit: Wolfgang Hoffman

Plant breeders began working to increase switchgrass yields more than two decades ago. Today results from this research are helping to make CenUSA’s vision a reality.

“CenUSA is responsible for us being able to do our field trials,” said Dr. Michael Casler, USDA-ARS research geneticist based in Madison, Wisconsin. Much of the work Casler and his team have done is centered around breeding switchgrass plants that are economically viable. The current goal is to breed plants that can produce ten tons of biomass per acre.

“Since the 1990’s we have increased yield by 55-60% but our goal is ten tons per acre so we still have a ways to go,” said Casler. He predicts switchgrass yields will reach their goal by 2025.

Beginning in 1992, researchers began using “routine selection” to improve switchgrass performance. Routine selection is the process of intentionally selecting plants that have desired traits like yield and winterhardiness.  Casler has made big breakthroughs in his breeding program by delaying switchgrass flowering time.

Plants from southern states such as Alabama and Texas have switchgrass strains that flower much later than their Northern relatives. However, these strains are not very winter-hardy and will likely not survive the first year in the Midwest. Casler and his team have been working to breed winterhardy strains that flower later in the season.

“Typically, switchgrass flowers in early August which is a problem because there’s still six weeks left in the season,” said Casler. “Our goal is to delay flowering time as far as we can into September.” Breeding plants that flower later in the season increases biomass yields because the plants will keep growing.

In addition to producing high-yielding bioenergy, switchgrass, a deep-rooted perennial, has been shown to improve the environmental performance of farming systems by reducing soil erosion and nutrient leaching. However, Keri Jacobs, an economics professor at Iowa State University, explains that producers are typically not compensated for non-market benefits, like soil and water quality, meaning most producers stay on the path that leads to more revenue; typically corn and soybeans. In addition, a perennial grass like switchgrass, can tie up farmland for ten years or even longer.

 “It’s like the chicken and the egg,” said Jacobs. “For switchgrass to be economically viable there needs to be a stable market for its use. Right now switchgrass for biofuel is not being produced on a commercial scale because there is not a commercial scale end user and traditional crops are more profitable. Greater yields and a reliable market will be the real keys to making switchgrass economically viable in the Midwest,” said Jacobs.