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Switchgrass cultivation requires standardized and well established agricultural practices in order to be productive

Summary​

Switchgrass cultivation involves well-established practices developed over decades of research and farming experience. Switchgrass is primarily grown from seed using tillage or no-tillage methods, with weed management being crucial during establishment. Once established, switchgrass requires minimal herbicide usage, but benefits from nitrogen fertilizer application to maintain high yields. Harvesting typically occurs once per year after a killing frost, using equipment similar to other forage crops. Storage is a major consideration as the crop's single annual harvest and bulk storage requirements represent significant logistical challenges for large-scale biofuel production. Switchgrass stands can be productively harvested for over 10 years, but resowing practices require further research to address soil carbon preservation concerns.

Switchgrass is a perennial herbaceous grass that has been extensively studied with the goal of maximizing its yield and profitability as an energy crop for the production of second generation biofuels. Switchgrass, being a native grass that has been cultivated extensively in the United States for close to eight decades, has a well-established cultivation and harvest process.

Establishing (planting) switchgrass​

Switchgrass is primarily grown from seed, which is the most desirable method of establishment for energy crop cultivation. Switchgrass can be cultivated through tillage or no-tillage methods, with no-tillage offering environmental and sustainability benefits that need to be weighed against pragmatic local environmental considerations of regular tillage. During establishment, weeds pose a challenge to successful cultivation, often requiring herbicide application 1. It is recommended that fertilizers are not applied during establishment as this can further encourage weed growth. Plant establishment is also the primary time where some form of irrigation may be required if precipitation levels are insufficient to support the growth of the plant 2. During the first year of growth, biomass production will reach approximately 50% of its full potential, with the second year achieving above 75% of yield potential 1.

Switchgrass Management​

After switchgrass is established and the threat of weeds has been minimized, very little herbicide usage is required throughout the remainder of the crop's lifetime, with one or two applications of herbicide typically being sufficient 1. In order to maintain high yields, application of nitrogen fertilizer is required. Rates of nitrogen application vary but generally are around 20 pounds of nitrogen per acre per ton of harvested biomass to maximize biomass yields, but this value can be reduced if the crop is harvested after a killing frost (a below freezing temperature event). This limits the nitrogen that is removed from the system as some of the nitrogen is sent back underground to the roots1. In general, there are adequate potassium and phosphorus levels in American soil profiles for switchgrass cultivation but some additional application may be required on a case-by-case basis 1.

Switchgrass harvesting​

Harvesting switchgrass is similar to other forage crops such as alfalfa and hay which requires commercially available equipment such as rotary head hay harvesters and balers 1. Switchgrass can have two harvests in a season, however a single harvest after a killing frost is recommended to maximize yields and future stand productivity 1. If managed correctly, switchgrass stands can be continuously harvested productively for more than 10 years 1.

Switchgrass storage​

A key challenge of switchgrass cultivation is that there is a single harvest per year, meaning that storage and handling becomes a vital logistical issue. The most cost-efficient method of switchgrass storage is through rectangular baling as it allows for easier transportation and secondary processing in the bioethanol plant 3. Round bales tend to perform better when stored for a longer period of time as they experience less storage losses if left uncovered however, it is generally recommended to use some form of protected storage such as tarps or structures 1.

The logistics of switchgrass handling and storage are considered one of the major challenges to developing a switchgrass biofuel industry. For a large-scale industry as would be required for an ambitious biofuel goal such as supplying 50% of the United States' domestic aviation fuel needs, baling alone may not be adequate because of the challenges related to the storage of large bulk volumes, transportation, and refining processes. Methods such as pelletization have been proposed to address these logistical issues 3.

Resowing switchgrass​

There is a significant gap in the literature relating to the best practices for resowing (reestablishing) switchgrass stands that have lost their productivity after their 10+ year lifespan. Due to the extensive below ground root system of switchgrass, conventional tillage may be required for reestablishment. Conventional tillage may result in much of the stored soil organic carbon (SOC) being released back into the atmosphere, reducing the soil rehabilitation benefits that switchgrass can provide 4. Further research into the best practices for resowing switchgrass is required to better quantify the sustainability benefits of switchgrass.

Sources​

Footnotes​

  1. Downing, M., Eaton, L. M., Graham, R. L., Langholtz, M. H., Perlack, R. D., Turhollow, A. F., ... & Brandt, C. C. (2011). U.S. billion-ton update: Biomass supply for a bioenergy and bioproducts industry (No. ORNL/TM-2011/224). Oak Ridge National Laboratory. ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9

  2. McLaughlin, S. B., Bouton, J. H., Bransby, D. I., Conger, B. V., Ocumpaugh, W. R., Parrish, D. J., Taliaferro, C. M., Vogel, K. P., & Wullschleger, S. D. (1998). Developing switchgrass as a bioenergy crop. In J. Janick (Ed.), Perspectives on new crops and new uses (pp. 282–299). ASHS Press. ↩

  3. Hess, J. R., Wright, C. T., & Kenney, K. L. (2007). Cellulosic biomass feedstocks and logistics for ethanol production. Biofuels, Bioproducts and Biorefining, 1(2-3), 181–190. https://doi.org/10.1002/bbb.26 ↩ ↩2

  4. Min, K., Nuccio, E., Slessarev, E., Kan, M., McFarlane, K. J., Oerter, E., Jurusik, A., Sanford, G., Thelen, K. D., Pett-Ridge, J., & Berhe, A. A. (2025). Deep-rooted perennials alter microbial respiration and chemical composition of carbon in density fractions along soil depth profiles. Geoderma, 455, 117202. https://doi.org/10.1016/j.geoderma.2025.117202 ↩