Switchgrass

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Switchgrass

Scientific classification

Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Liliopsida
Order:	Poales
Family:	Poaceae
Genus:	Panicum
Species:	P. virgatum

Binomial name

Panicum virgatum
L.

Switchgrass (Panicum virgatum) is a warm-season grass and is one of the dominant species of the central North American tallgrass prairie. Switchgrass can be found in remnant prairies, along roadsides, pastures and as an ornamental plant in gardens. Other common names for this grass include tall panic grass, Wobsqua grass, lowland switchgrass, blackbent, tall prairiegrass, wild redtop and thatchgrass.

1 Properties
2 Uses
- 2.1 Biofuel
  - 2.1.1 Prominent use in Tennessee alternative fuel program
3 See also
4 References
5 External links

[edit] Properties

Switchgrass is a hardy, perennial bunch grass which begins growth in late spring. It can grow up to 1.8-2.2 m in height, but is typically shorter than Big Bluestem grass or Indiangrass. The leaves are 30-90 cm long with a prominent midrib. Switchgrass uses C4 carbon fixation, giving it an advantage in conditions of drought and high temperature.^[1]

Its flowers have a well-developed panicle often up to 60 cm in length and bears a good crop of fruits, which are 3 to 6 mm long and up to 1.5 mm wide. The fruits are developed from a single-flowered spikelet. Both glumes are present and well developed. 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.

[edit] Uses

Switchgrass is grazed by certain animals, used as ground cover to control erosion and farmed as forage for livestock. As a drought resistant ornamental grass, it is easily grown in average to wet soils and in full sun to part shade. Establishment is recommended in the spring, at the same time as maize is planted.

[edit] Biofuel

Switchgrass is often considered a good candidate for biofuel, especially ethanol fuel, production due to its hardiness against poor soil and climate conditions, rapid growth and low fertilization and herbicide requirements. Switchgrass is also perennial, unlike corn and sugarcane, and has a huge biomass output, the raw plant material used to make biofuel, of 6-10 tons per acre.^[2]^[3] President George W. Bush mentioned this usage in his 2006 State of the Union address.

Switchgrass has the potential to produce the biomass required for production of up to 100 gallons (380 liters) of ethanol per metric ton.^[4] This gives switchgrass the potential to produce 1000 gallons of ethanol per acre, compared to 665 gallons for sugarcane and 400 gallons for corn.^[5]

However, there is debate on the viability of switchgrass as a biofuel. University of California, Berkeley professor Tad Patzek claims that switchgrass has a negative ethanol fuel energy balance, requiring 45 percent more fossil energy than the fuel produced.^[6] In a 2007 lecture Professor Richard Muller, also of the University of California, Berkeley, noted that it is the conversion of switchgrass biomass into ethanol which introduces significant inefficiencies. He also noted that The Helios Project at Lawrence Berkeley Laboratory is actively trying to engineer metabolic pathways in bacteria to more efficiently convert cellulose to ethanol.

On the other side, David Bransby, professor of energy crops at Auburn University, has found that for every unit of energy input, switchgrass yields four units out.^[7] It is Bransby's work that was the source for President Bush's comments in the 2006 State of the Union address.

[edit] Prominent use in Tennessee alternative fuel program

In January 2007, Tennessee Governor Phil Bredesen announced that his proposed 2007-08 State budget would include $61 million for a comprehensive alternative fuels strategy designed "to position Tennessee to be a national leader in the production of biomass ethanol and related research."^[8] Bredesen proposed this funding in combination with $11.6 million in existing funding for an ongoing related project at Oak Ridge National Laboratory (ORNL), for a total proposal representing a $72.6 million comprehensive plan.^[9] Scientists at ORNL and the University of Tennessee (UT) Institute for Agriculture have developed ethanol from switchgrass, a crop that can be grown virtually anywhere in Tennessee.^[10]