Panicum virgatum, commonly known as switchgrass, is a perennial warm season bunchgrass native to North America, where it occurs naturally from 55°N latitude in Canada southwards into the United States and Mexico.

When ripe, the seeds sometimes take on a pink or dull-purple tinge, and turn golden brown with the foliage of the plant in the fall.

[3] Unlike corn, switchgrass can grow on marginal lands and requires relatively modest levels of chemical fertilizers.

Much of North America, especially the prairies of the Midwestern United States, was once prime habitat to vast swaths of native grasses, including switchgrass, indiangrass (Sorghastrum nutans), eastern gamagrass (Tripsacum dactyloides), big bluestem (Andropogon gerardi), little bluestem (Schizachyrium scoparium)[4] and others.

As European settlers began spreading west across the continent, the native grasses were plowed under and the land converted to crops such as corn, wheat, and oats.

[7] As a warm-season perennial grass, most of its growth occurs from late spring through early fall; it becomes dormant and unproductive during colder months.

This diversity, which presumably reflects evolution and adaptation to new environments as the species spread across the continent, provides a range of valuable traits for breeding programs.

[10] Switchgrass’ suitability for cultivation in the Gran Chaco is being studied by Argentina's Instituto Nacional de Tecnología Agropecuaria (INTA).

Most bioenergy conversion processes for switchgrass, including those for cellulosic ethanol and pellet fuel production, can generally accept some alternative species in the harvested biomass.

Additionally, switchgrass is grown as a drought-resistant ornamental grass in average to wet soils and in full sun to part shade.

[18] Switchgrass has been researched as a renewable bioenergy crop since the mid-1980s, because it is a native perennial warm season grass with the ability to produce moderate to high yields on marginal farmlands.

It is now being considered for use in several bioenergy conversion processes, including cellulosic ethanol production, biogas, and direct combustion for thermal energy applications.

The main agronomic advantages of switchgrass as a bioenergy crop are its stand longevity, drought and flooding tolerance, relatively low herbicide and fertilizer input requirements, ease of management, hardiness in poor soil and climate conditions, and widespread adaptability in temperate climates.

[19] However, these yields were recorded on small plot trials, and commercial field sites could be expected to be at least 20% lower than these results.

During the bioconversion process, the lignin fraction of switchgrass can be burned to provide sufficient steam and electricity to operate the biorefinery.

[34] The Show-Me-Energy Cooperative (SMEC) in Missouri[35] is using switchgrass and other warm-season grasses, along with wood residues, as feedstocks for pellets used for the firing of a coal-fired power plant.

[37] Research has found switchgrass, when pelletized and used as a solid biofuel, is a good candidate for displacing fossil fuels.

Switchgrass pellets were identified to have a 14.6:1 energy output-to-input ratio, which is substantially better than that for liquid biofuel options from farmland.

These technical problems now appear to have been largely resolved through crop management practices such as fall mowing and spring harvesting that allow for leaching to occur, which leads to fewer aerosol-forming compounds (such as K and Cl) and N in the grass.

[38][39][40] Switchgrass is also being used to heat small industrial and farm buildings in Germany and China through a process used to make a low quality natural gas substitute.

[41] Bai et al. (2010) conducted a study to analyze the environmental sustainability of using switchgrass plant material as a feedstock for ethanol production.

In 2014, a genetically altered form of the bacterium Caldicellulosiruptor bescii was created which can cheaply and efficiently turn switchgrass into ethanol.

[43][44] In a novel application, US scientists have genetically modified switchgrass to enable it to produce polyhydroxybutyrate, which accumulates in beadlike granules within the plant's cells.

Since it, along with other native grasses and forbs, once covered the plains of the United States that are now the Corn Belt, the effects of the past switchgrass habitat have been beneficial, lending to the fertile farmland that exists today.

[47] Its root system, also, is excellent for holding soil in place, which helps prevent erosion from flooding and runoff.

Conservation districts in many parts of the United States use it to control erosion in grass waterways because of its ability to anchor soils while providing habitat for wildlife.

Switchgrass is an excellent forage for cattle; however, it has shown toxicity in horses, sheep, and goats[49][50][51] through chemical compounds known as saponins, which cause photosensitivity and liver damage in these animals.

[52] Switchgrass becomes stemmy and unpalatable as it matures, but during the target grazing period, it is a favorable forage with a relative feed value (RFV) of 90–104.

[53] The grass's upright growth pattern places its growing point off the soil surface onto its stem, so leaving 25 cm of stubble is important for regrowth.

[55] Depending on how thickly switchgrass is planted, and what it is partnered with, it also offers excellent forage and cover for other wildlife across the country.