Cup plant holds double benefits
By LANCE NIXON
South Dakota State University scientists are exploring a native perennial called the cup plant as a potential new biomass crop that could also store carbon in its extensive root system and add biodiversity to biomass plantings.
Researchers are exploring whether cup plant could be grown in low, moist prairies generally unfit for cropland. It would be grown and processed along with native grasses grown for biomass.
“Down the road there’s going to be a need, and maybe even a market, for plants that can store carbon underground and be part of a biomass production system,” says SDSU professor Arvid Boe, a plant breeder and lead investigator on a grant of $324,336 from the U.S. Department of Energy that’s channeled through the SDSU-based North Central Sun Grant Center.
• SDSU is studying the cup plant’s potential for biomass production.
• The cup plant would be grown with native grasses.
• It grows 7 feet tall and stores carbon in its roots.
Project goals include studying genetic variation and developing molecular markers in cup plant populations from the eastern Great Plains; developing new cultivars that can be grown in combination with other biomass crops; determining best practices such as seeding rate, row spacing, harvest timing and nutrient management; determining life histories of insect pests; and determining biochemical composition.
Boe says cup plant, or Silphium perfoliatum, is a member of the sunflower family found in moist, low ground in the eastern Great Plains, where it can grow more than 7 feet tall. It has large seeds and good seedling vigor, and it yields a lot of biomass.
“It’s conspicuous as a very productive forb in a tallgrass prairie where you have your major grasses, such as big bluestem, switchgrass and prairie cordgrass,” Boe says. “We haven’t come up with too many things to grow with our grasses to add biodiversity to these biofuel mixtures that we’re anticipating growing down the road. It’s very compatible with such things as switchgrass and prairie cordgrass and big bluestem.”
Boe says scientists don’t envision planting entire fields of cup plant. Instead they view it as one in a mix of biomass species that would be seeded in zones best suited for them, just as in the original tallgrass prairie.
Boe and his colleagues borrow a term used years ago by conservationist Erling Jacobson of the U.S. Department of Agriculture’s Soil Conservation Service to speak of “sculpting the landscape” with native grasses best suited to different locations in the prairie.
“We don’t necessarily have a mix at any particular area, but we have various species wherever they’re best adapted on the landscape. It doesn’t make any sense for us to mix switchgrass, big bluestem and prairie cordgrass together and plant it over a whole field. After five years, the species that are best adapted are going to take over anyway in their particular niche,” Boe says. “We’re going to go in, and we’re going to plant essentially monocultures of these various species where they were in the original tallgrass prairie. There were monocultural stands in the tallgrass prairie, but they were zonal.”
Ideal for marginal land
Cup plant is probably best suited to the same terrain that switchgrass likes, Boe says, just above the prairie cordgrass zone and possibly all the way up to the edge of the big bluestem zone.
“It fits the low prairie or moist prairie-type environment that we’re shooting for and might even work out pretty well with prairie cordgrass,” Boe says. “So we add diversity to that low prairie environment that is marginal land not suitable for cropland and also not a good environment for switchgrass to grow. We’re not taking cropland out of production to put cup plant in there. We think it will grow in areas where crops wouldn’t survive or couldn’t even be planted on a regular basis.”
Nixon is a writer with SDSU AgBio Communications.
Pluses, minuses of biodiversity
Cup plant is likely to increase biodiversity in a plant community because it attracts a variety of insects and even birds. Goldfinches drink out of the leaves, and the stems provide perch areas for grassland birds.
Paul Johnson, an SDSU entomologist, is interested in a species of moth called Eucosma giganteana, first described by a scientist in 1881, that seems to have cup plant as its only host plant.
“In South Dakota, the giant eucosma has recently become more than just another interesting prairie insect because of interest in using cup plant as a biomass crop,” Johnson says.
Larvae feed in the rapidly growing terminal structures, especially buds, where the damage can be extensive, often leading to complete loss of floral production. The end result can be significant loss of biomass through stunting and loss of vigor in the plants.
“Turning cup plant into a commodity thus converts the giant eucosma into a pest of significant concern,” Johnson says. “It’s another case of a native prairie plant becoming a crop and the conversion of a previously neglected native plant predator to a pest.”
Johnson is studying the life history of the giant eucosma as part of the SDSU project.
Perennial grasses will always be the base for biomass production, but cup plant is a complementary species, scientists say. Increasing the number of species in the mix reduces the probability of plant disease and insect pests attacking one species and causing large losses in yield.
NEW CROP: Arvid Boe, SDSU plant science professor, inspects a cup plant. The perennial has potential as a biomass crop.
This article published in the May, 2010 edition of DAKOTA FARMER.
All rights reserved. Copyright Farm Progress Cos. 2010.