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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #309626
Title: Grass invasion into switchgrass managed for biomass energy

Author
item Mitchell, Robert - Rob
item Vogel, Kenneth

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2015
Publication Date: 7/31/2015
Citation: Mitchell, R., Vogel, K.P. 2015. Grass invasion into switchgrass managed for biomass energy. BioEnergy Research. DOI:10.1007/s12155-015-9656-4.

Interpretive Summary: Switchgrass is native to North American grasslands east of the Rocky Mountains and has been planted for forage and conservation purposes for more than 75 years. Although switchgrass is considered to be the model herbaceous perennial bioenergy feedstock for use on marginally-productive cropland, there are concerns that high-yielding biofuel crops like switchgrass could become invasive. However, there is little field-based evidence to support this concern. We used a long-term switchgrass study to evaluate the persistence and competitive ability of switchgrass under different N rate and harvest date treatments after 10 years of management as a biomass energy crop on a site marginally productive for row crops. The most common grasses invading switchgrass stands were big bluestem, smooth bromegrass, Kentucky bluegrass, and intermediate wheatgrass, with big bluestem being the most common, occurring in 89% of the plots. The greatest invasion by grasses occurred in plots to which 0 N had been applied and with harvests at anthesis. Limited invasion occurred in plots receiving at least 60 kg of N ha-1 or in plots harvested after frost. There were differences among cultivars with Cave-in-Rock being more resistant to invasion than Trailblazer. There was no evidence of switchgrass from this study invading into border areas or adjacent fields after 10 years of management for bioenergy. This study indicates switchgrass is more likely to be invaded by other grasses than to be invasive in the Great Plains and Midwest USA.

Technical Abstract: Switchgrass (Panicum virgatum) is a warm-season perennial grass and is the model herbaceous perennial bioenergy feedstock. Although it is indigenous to North American grasslands east of the Rocky Mountains and has been planted for forage and conservation purposes for more than 75 years, there is concern that switchgrass grown as a biofuel crop could become invasive. Our objective is to report on the invasion of warm-season and cool-season grasses into the stands of two switchgrass cultivars following 10 years of management for biomass energy under different N and harvest management regimes in eastern Nebraska. Switchgrass stands were invaded by big bluestem (Andropogon gerardii), smooth bromegrass (Bromus inermis) and other grasses during the 10 years. The greatest invasion by grasses occurred in plots to which 0 N had been applied and with harvests at anthesis. Limited invasion occurred in plots receiving at least 60 kg of N ha-1 or in plots harvested after frost. There were differences among cultivars with Cave-in-Rock being more resistant to invasion than Trailblazer. There was no observable evidence of switchgrass from this study invading into border areas or adjacent fields after 10 years of management for biomass energy. Results indicate switchgrass is more likely to be invaded by other grasses than to be invasive in the Great Plains and Midwest USA.