Properties

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Uses

Background

Much of North America, especially the prairies of the Midwest, was once home to vast swaths of native grasses including Switchgrass (Panicum virgatum), Indiangrass (Sorghastrum nutans), Eastern Gamagrass (Tripsacum dactyloides), Big Bluestem (Andropogon gerardii), Little Bluestem (Schizachyrium scoparium) and others. As settlers began spreading out across the continent, the native grasses were replaced by crops such as corn and wheat.Introduced grasses such as fescue, bluegrass, and orchardgrass replaced the native grasses.
   Today, as [biofuel]s are becoming a mainstay in the headlines, the public is hearing about Switchgrass as an excellent prospect for providing ethanol for our cars. There are also other benefits and opportunities for switchgrass in our economy.

Switchgrass is very versatile and adaptable. It can grow and even thrive in many weather conditions, lengths of growing seasons, soil types and land conditions. Its distribution spans south of latitude 55ºN from Saskatchewan to Nova Scotia and south over most of the United States east of the Rocky Mountains (Sizler, 2007) As a warm season perennial grass, most of its growth occurs from late spring through early fall and becomes dormant and unproductive during colder months. Thus, the productive season in the northern regions can be as short as three months, but up to eight months in the Gulf Coast area (Ball et al., 2002).

One of the benefits of switchgrass is through soil amendment and conservation. Switchgrass has a deep fibrous root system – nearly as deep as the plant is tall. Since it, along with other native grasses and forbs, once covered the plains of the United States that are now the Corn Belt, you could say that they still help feed the world today. Their deep fibrous roots left a very deep rich layer of organic matter in the soils; making those mollisol soils some of the most productive in the world. By returning switchgrass and other perennial prairie grasses to the agricultural scene, many marginal soils will benefit from their deep root systems through increased organic matter levels, permeability, and fertility.

As soil erosion, both from wind and water, is of great concern in all regions, the adaptability of Switchgrass is very appealing. Due to its height, it can be used as a low part of a wind erosion barrier (USDA NRCS, 2001). Its root system is excellent for holding soil in place. Some highway departments have used it in their seed mixes when re-establishing growth along roadways (Kansas Department of Transportation). It can also be used on strip mine sites, dikes(4), and pond dams. Conservation districts are already using it in many parts of the country to control erosion in grass waterways because of its excellent ability to anchor soils while also doubling as native habitat for wildlife.

Switchgrass is well-known among wildlife conservationists as a favorite among the upland game bird species such as pheasant, quail, grouse and song birds. Its small seeds are well-liked among them. Wild turkeys are also commonly found in Switchgrass stands. Depending on how thickly switchgrass is planted, and what it's partnered with, it can offer excellent forage and cover for a wide variety of other wildlife across the country. For those producers who have switchgrass stands on their farm, they consider this benefit an aesthetic one as much as an environmental one because they enjoy watching the wildlife. Some members of Prairie Lands Bio-Products, Inc. in Iowa have even turned this benefit into a profitable one by leasing their switchgrass land for hunting during the proper seasons (6). In an agricultural setting, like growing many acres of switchgrass for biofuel, the advantages to wildlife can still stand. Although the Wildlife Society suggests that rather than harvest an entire field at once, strip harvesting could be practiced so the entire habitat isn't removed at one time for the wildlife that have made the switchgrass their home (7).

There is another type of conservation that doesn't draw as much attention as soil and wildlife conservation normally does: the conservation of our native plant species, such as switchgrass. By bringing switchgrass to the front of the news, we're revisiting a part of our nation's past that many have perhaps never thought about: when North American was covered in "that vast seas of grasses, so thick and high that pioneers said it could swallow a rider on horseback."(19) Maybe this will stir interest by a broader spectrum of the population in switchgrass and other native species that were once a part of our landscape which have gone to the wayside. There are groups dedicated to helping inform the public about native plant species, such as this scholarly group at the University of Idaho who has a published the Native Plants Journal and its online twin http://nativeplants.for.uidaho.edu/ dedicated to educating the public about native plant species (8), as well as groups with web sites like www.grownative.org, international organizations such as the National Audubon Society, and state organizations like the Virginia Native Plant Society. These groups can offer information about native species' habitat, pests, growth patterns, positive attributes and negative ones. They can also offer some interesting tidbits of history and anecdotes about some plants.

Biofuel

Switchgrass is 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 (19). It can also be pressed into fuel pellets which are burned in special furnaces used to heat homes, which typically use corn or wood pellets (9).

Forages

Switchgrass is an excellent forage for cattle; however, it has shown toxicity in horses, sheep and goats (10, 11, 12) through chemical compounds known as saponins, which cause photosensitivity and liver damage in these animals. Researchers are continuing to learn more about the specific conditions under which the switchgrass must be in order to cause harm to these species, but until more is discovered, it's recommended that switchgrass not be fed to them. For cattle, however, it can be fed as hay, or grazed.

Grazing switchgrass calls for watchful management practices to ensure survival of the stand. It is recommended that grazing begin when there's 18 – 22 inches of growth, to stop grazing when there are 8 – 12 inches of stubble left, and to rest the pasture 30 – 45 days between grazing periods (13). Switchgrass becomes very stemmy and unpalatable as it matures, but during the target grazing period, it's a highly favorable forage with a relative feed value (RFV) of 90-104 (14). The grass' upright growth pattern places its growing point off the soil surface onto its stem, so leaving 8 – 12 inches of stubble is important for regrowth. When harvesting switchgrass for hay, the first cutting occurs at the late boot stage – around mid-June. This should allow for a second cutting in mid-August, leaving enough regrowth to survive the winter. (15)

Establishment

Switchgrass stands can last for many years. The rhizome root system grows deeply into the soil and the plant efficiently uses the C4 cycle to fix carbon through photosynthesis for energy production. But establishment takes the proper steps and patience.

The first step is choosing your planting method, which will then determine how you prepare your seedbed. Various states' Extension Services recommend different planting methods for switchgrass for their regions, including tillage, no-till, broadcast and sod-seedling (15, 16, 17, 18). No matter which is used, initial weed control is essential since switchgrass is slow to establish, and the use of broadleaf herbicides over the switchgrass seedlings could cause the crop great damage. The seeding rate is five to six pounds of pure live seed (PLS) per acre in the spring (April – May) at ¼ - ½ inch planting depth (3). There are approximately 280,000 switchgrass seed per pound (3). Fortunately, the seed is large and smooth enough that it can be planted with most drills (16). Therefore, farmers choosing to move some of their acres into this crop for either biofuel or other reasons may not have to purchase a new piece of equipment. Germination occurs in approximately 5 – 7 days (15). No fertilizer is required in the establishment year, nor is it recommended: switchgrass is very efficient at utilizing the available nutrients in the soil and adding fertilizer would only increase the weed competition (9).

Once established, it takes three years for a stand of switchgrass to reach its full potential (9). According to David Bransby at Auburn University, it'll produce a quarter to a third of its full potential in its first year and two-thirds in its second year (20). It is sometimes suggested that the stand not be harvested during the establishment year (9). Afterwards, each region has its own recommendations for fertilizer rates. The timing of harvesting depends upon how the switchgrass is to be used, and weed control can be addressed with limited herbicides, controlled burns, and mechanical methods.

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