Switchgrass Long Range Field Planting Plan

Plant Accession Data

• accessions: 9005438 and 9005439
• common name: switchgrass
• scientific name: Panicum virgatum L.

Description

Swichgrass is a native, warm season, sod forming grass that occupies the more mesic portions of riparian or wetland plant communities. This grass has extensive, scaly creeping rhizomes capable of forming a dense sod. The plants reach an overall height of 1 to 2 meters. The seedheads )panicle) are open/diffuse with the spikelets on long pendicles, the lower ones arranged in a series of whorls. The spikelets are two-flowered with only the upper one fertile. The lemma surface of the fertile floret is smooth and shiny. A distinctive vegetative characteristic is the hairy ligule (1.5 to 3.5 millimeters long) in combination with a V-shaped patch of wavy hair on the upper leaf surface originating at the collar. Leaf blades are flat and firm (10 to 60 centimeters long, 0.3 to 1.5 centimeters wide).

Origin

9005438 is a composite of three Wyoming collections; Wy-86 (Platte County, elevation 1,450 meters, precipitation 300 millimeters), Wy-141 (Goshen County, elevation 1,325 meters, precipitation 340 millimeters), and Wy-291 (Platte County, elevation 1,460 meters, precipitation 300 millimeters). 9005439 originated in Platte County, Wyoming (elevation 1,455 meters, precipitation 300 millimeters). A total of 17 Montana collections and 10 Wyoming collections have been evaluated at the Bridger Plant Materials Center (PMC), being originally compared to release cultivars such as 'Blackwell' and 'Neb-28' and later 'Forestberg' and 'Dacotah'. 9005438 was selected for its late maturity (southern type), while 9005439 was selected for its earlier maturity (northern type). These two accessions have exhibited good productivity and longevity in the northern latitudes when used as late summer livestock forage and wildlife food and cover.

Adaptation

In Montana and Wyoming switchgrass is primarily found in remnants of the mixed grass prairie (Major Land Resource Areas 67 - Central High Plains, 60 - Pierre Shale Plains and Badlands, and 58 - Northern Rolling High Plains). Land cultivation and heavy grazing has greatly reduced the abundance of this species, limiting it to scattered stands or individual plants. It can be found on subirrigated, lowland, and overflow sites in association with sedges, rushes, western wheatgrass and occasionally other warm season grasses such as prairie cordgrass and big bluestem. Switchgrass is usually associated with heavier clayey soils, but can be found on coarse soils if soil moisture availability is good. The purpose of field testing of this material is to determine how far into the shortgrass prairies and foothills this species will successfully establish and persist.

Establishment

Seed should be planted into a firm weed-free seedbed at a depth of one centimeter. If planted by itself, the seeding rate should be about 4 kilograms per hectare but if included in a mix 2 kilograms per hectare or less. For reclamation of lowland sites or for establishment of wildlife habitat switchgrass is commonly seeded with bluestems, indiangrass, and sideoats grama. As with most of the warm-season grasses, spring seeding is recommended. Establishment of warm-season grasses is not always successful in eastern Montana and eastern Wyoming because of the climatic patterns of early spring moisture, followed by hot dry early summer months; a climatic pattern more conducive to cool-season grass establishment.

Uses

At the interface between the mixed grass prairie and the short grass prairies there is a need for supplemental forage during the late summer and early fall. Cool season grasses have matured, resulting in lower palatability and reduced forage quality. The establishment of warm-season complimentary pastures would provide an abundance of high quality forage at a time of critical forage shortage of most cool-season species. Under irrigation or subirrigation switchgrass is productive enough to be harvested for hay and still provide enough regrowth for late summer and fall grazing. The tall upright plants and the abundance of high protein seed make switchgrass an ideal wildlife cover and food crop. The seed is relished by upland game birds as well as deer and antelope.

Seed Production

Switchgrass seed is relatively easy to produce. Reliable seed production requires supplemental irrigation or a site receiving at least 450 millimeters of precipitation. Row spacing of 60 to 90 centimeters is recommended to allow cultivation and maximize productivity. The upright stature and uniformity of this species allow for direct combining, however with dense stands swathing and harvesting out of a cured windrow is recommended. Seed production at the Bridger Plant Materials Center has averaged 400 kilograms per hectare (10 year average). Management of seed production fields include aftermath removal (baling or fall or early spring burning), spring fertilization (80 kilograms per hectare nitrogen, 40 kilograms per hectare phosphorus), close cultivation, and chemical broadleaf weed control.

Planting Information

Culture and Management ¹

In accordance with applicable practice standards and specifications as stated in Section IV of the Field Office Technical Guide.

Field Planting Size

Minimum five (5) acres each, featured cultivar and standard of comparison entry.

Seeding Rate

Three (3 ) pounds pure live seed (PLS) per acre in pure stands. (Approximately 350,000 seeds per pound, 8 seeds per square foot at one (1) pound PLS per acre. Should be used in monocultures, or in mixtures with forbs, shrubs, or legumes for complementary pastures. Adjust rate accordingly for mixtures.

Standard of Comparison

• 'Dacotah' switchgrass
• 'Forestberg' switchgrass
• 'Covar' sheep fescue

Evaluation

Herbaceous plant performance will be requested annually for the first five (5) years and the tenth (10th) year following establishment. Use standard evaluation forms.

¹ Seedbed preparation, planting methods, seed placement depth, weed control, and stand establishment management..

² Field office location managed by the respective Natural resource Team.

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Last Modified: 07/05/2007