Alamo Switchgrass
Alamo switchgrass (Panicum virgatumis) is a perennial, sod-forming grass growing between 3 and 5′ tall. Switchgrass is a native grass and given suitable soil conditions can be found throughout the USA except California and the Pacific Northwest. Best soils are moderately deep to deep, somewhat dry to poorly drained, sandy to clay loam soils unless severe weed competition exists during establishment. In the East, it performs well on shallow and droughty soil. Switchgrass does poorly on heavy soils.
Alamo switchgrass is readily distinguished from other warm-season grasses by the white patch of hair found at the point where the leaf attaches to the stem. This patch is also visible in young plants. Plants are blue-green in color and usually slightly waxy. The seed head is an open, spreading panicle.
Switchgrass provides good warm-season pasture and high quality hay for livestock. Switchgrass is also renowned for its heavy growth during late spring and early summer. Alamo can be employed on its own for pasture or in seed mixtures for warm-season grazing or hay.
When it comes to erosion control switchgrass is possibly the most valuable of the native grass across a wide range of sites. It’s a valuable plant for soil stabilization on strip-mine spoils, sand dunes, dikes, and similar critical areas. Switchgrass has also bee used for low windbreak plantings in truck crop fields.
In addition to its benefits to livestock and in erosion control switchgrass also provides excellent nesting and fall and winter cover for pheasants, quail, and rabbits. It holds up well in heavy snow and is used on shooting preserves. In addition the seed provides pheasants, quail, turkeys, doves, and songbirds with a food source.
Despite the aforementioned benefits of switchgrass its potential use as a renewable biofuel resource may prove to be its greatest. Interest in this use for switchgrass has been increasing in recent years, primarily in the Southern United States. The Booneville, Arkansas, Plant Materials Center (PMC) and the Plant and Soil Science Department of Oklahoma State University (OSU) are cooperating to evaluate several upland types of switchgrass for use as a biomass energy resource.
OSU has evaluated selections of upland types of switchgrass for several years. The development of hybrid progeny with substantial heterosis for increased biomass yield will ultimately result in improved hybrid cultivars for the Central and Southern United States.
The PMC is currently evaluating a number of improved lines and commercially available cultivars for their dry-matter potential and environmental adaptation. Results of this study may contribute to producers cashing in on a growing demand for renewable fuels and a decrease on our dependency on fossil fuels.
When used for pasture or hay switchgrass should be seeded in pure stands as it is more manageable alone than in mixes. Its slick, free-flowing seed can be planted with most seed drills or with a broadcast spreader. The optimal or best time to plant is between December and the end of May. In the Central Plains 3-5 pounds PLS per acre is the recommended planting rate.
Switchgrass seeds are smooth and shiny, with about 426,000 per pound.
Seedbeds should be firmed with a roller prior to drilling or broadcasting the seed. If seeds are planted using the broadcast method, roll the area after seeding to help cover the seed. When drilled, seeds should be planted 1/4 inch deep. No-tillage seeding in closely grazed or burned sod has been successful where clipping, grazing, or proper herbicides accomplish sod control.
Phosphorus and potassium should be applied according to soil tests before or at seeding. Nitrogen should not be used at seeding time as it will stimulate weed growth.
To control weeds during initial growth mow switchgrass to a height of 4 inches in May or 6 inches in June or July. While grazing is generally not recommended the first year, a vigorous stand may be grazed late in the year. However, grazing periods must be short with at least 30 days of rest provided between grazings. Switchgrass is the earliest maturing of the common native warm-season grasses and it is ready to graze in early summer.
Established stands of switchgrass may be fertilized in accordance with soil tests. Phosphorus and potassium may not be needed if the field is grazed since these elements will be recycled back to the soil by the grazing animal. Apply nitrogen after switchgrass has begun to produce using a single application in mid-to-late May or a split application in both May and early July. Avoid high rates of nitrogen because carry-over could spur cool-season grass growth and harm young plants the following spring.
Switchgrass will benefit from burning of plant residues just prior to the initiation of spring growth. Burning fields once every 3 to 5 years decreases weed competition, eliminates excessive residue and stimulates switch grass growth. Switchgrass used for wildlife food and cover should be burned once every 3 to 4 years to reduce mulch accumulations that restrict the movement of hatchlings and attract nest predators.
Under continuous grazing management, begin grazing switchgrass after it has reached a height of 14 to 16 inches, and stop when plants are grazed to within 4 inches of the ground during late spring, 8 inches in early summer, and 12 inches in late summer. A rest before frost is needed to allow plants to store carbohydrates in the stem bases and crown. Plants may be grazed to a height of 6 to 8 inches after frost. The winter stubble is needed to provide insulation.
With management intensive systems, grazing can begin in the first paddocks when plants reach a height of 10 inches and should not be grazed below a stubble height of 6 to 8 inches. Grazed paddocks need to be rested 30-60 days before being grazed again.
- Download this information as a printable .pdf fact sheet. Alamo Switchgrass Fact Sheet
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