AMES, Iowa – New research at Iowa State University shows that using advanced planting techniques can triple the amount of biomass produced by the perennial, bioenergy crop miscanthus in its establishment year. This would significantly increase the plant’s potential to store carbon and improve its economic viability for producers.
Agricultural lands hold significant potential for CO2 sequestration, particularly when utilizing perennial biomass crops. Among these, Miscanthus × giganteus (mxg) stands out due to its high productivity and carbon sequestration capabilities.
“There are already markets for mxg in Iowa,” said Andy VanLoocke, associate professor of agronomy, a leading researcher on the project. “Our new study suggests that we’ve been underestimating its potential for economic and environmental benefits during the crop’s initial growing season.”
The findings were published this month in GCB Bioenergy. The project was a collaboration between Iowa State and University of Illinois scientists.
As part of the study, the Iowa State team analyzed the carbon uptake of mxg during its establishment year (2019) at the Sustainable Advanced Bioeconomy Research (SABR) farm in Iowa, where it was planted on land previously in conventional row crops. Researchers used advanced planting technology, allowing a much higher density of mxg plants per unit area than in previous U.S. studies.
Mxg is a perennial crop planted by rhizomes, not by seed. Midwest research plots so far have largely used customized planters, and even partial hand labor, to plant individual rhizomes. The Iowa study took advantage of new, mechanized planting equipment that can plant more quickly and easily increase planting density.
At the end of the first year after planting, SABR’s mxg had a threefold increase in carbon uptake compared to a similar cornbelt study site at the University of Illinois Energy Research Farm. The Illinois mxg crop was established with lower planting density and pre-commercial planting equipment.
“Our plots have been growing well since 2019, and in Illinois, where the mxg plots were established a decade earlier, the miscanthus is still growing well with only slight dips in productivity,” VanLoocke said. “Miscanthus requires very little fertilization or pesticide use, so expenses are very low after the initial planting. This also means it has significant potential environmental benefits, including for water quality.”
Historically, mxg was rarely harvested in the first growing season and had been shown to have a highly variable net ecosystem carbon exchange, or NEE, within the first growing season. Management practices that allow for first-season harvests and increased carbon uptake could significantly improve the early economics and environmental impacts of mxg crops.
“At least for now, mxg, which has high cellulose content, is not expected to be used widely for a liquid fuel like ethanol, but it can perform well as biomass-based fuel,” VanLoocke said. “It also has potential markets as animal bedding and in biodegradable cardboard.”
He credits Aslan-Sungur “Rojda” Guler, the study’s first author, a research scientist in agronomy and the U.S. Department of Energy (DOE) Center for Advanced Bioenergy and Bioproducts Innovation at Iowa State, with planning and managing the detailed instruments and computational methods required to painstakingly track the crop’s complex daily carbon dynamics over the course of the year.
Tower and related equipment that help measure, track and analyze carbon fluxes and related changes in crop fields. Photo illustration by Aslan-Sungur “Rojda” Guler, Department of Agronomy, Iowa State University.
“Our results strongly suggest that increasing mxg planting density can enhance carbon uptake,” Guler said. “But we need more research and economic analyses to better understand carbon flux and other aspects of the plant’s costs and benefits under different environmental conditions and management practices.”
The research team also included Nic Boersma, research scientist in agronomy and the DOE Center for Advanced Bioenergy and Bioproducts Innovation at Iowa State. Other partners were Caitlin Moore, Emily Heaton and Carl Bernacchi with the Department of Crop Sciences and DOE Center for Advanced Bioenergy and Bioproducts Innovation at the University of Illinois.
Funding for the project came from the Department of Energy and the Iowa Agriculture and Home Economics Experiment Station.
