Switchgrass Establishment and Research
16th June 2006
SWITCHGRASS
Â
Characteristics:
 Switchgrass is a warm season, perennial grass that grows from early spring until frost. If left unharvested, it has coarse stems that can grow 3-7 feet tall. Leaves are flat (1/4-1/2 inches wide) and long (up to 30 inches). The plants flower in August-September with seed heads (open panicles) extending above the leaves, somewhat similar to fall panicum. The plants are bunch-like in appearance, and have short rhizomes in spring. Leafy regrowth develops from basal tillers and shoots near soil surface emerging along the lower stems. During the spring, rhizome buds produce aerial shoots; later in the year they produce new rhizomes. Stem buds are potentially active during late spring when rhizome bud activity is reduced; these stem buds become active if the apical meristem (developing seedhead) is removed by mowing or grazing.
          Â
           Plants are ready for grazing (in Raleigh) about 2 weeks later than fescue but about 4 weeks earlier than coastal bermudagrass. See Table 1.
Adaptation:
            Switchgrass is one of the most widely adapted plants; it is found growing on a wide range of soil types in all but five of the states. It was one of the major tall prairie grasses that covered the Great Plains when the pioneers headed west in the 1800′s. It grows best on well drained soils with good moisture supply, however, it will grow on droughty or
 moderately wet soils and will tolerate only occasional flooding.
Varieties to Use:
Â
Cave-in-rock, Alamo, Kanlow, Blackwell.
Seed:
Â
           There is some concern that the official germination % listed on the seed tag (of new crop seeds) may not represent what will happen when planted. Frequently 20 to 40% of switchgrass seed are dormant in the first 6 to 9 months after harvest. Standard germination tests, which includes a wet-pre-chill treatment that breaks dormancy in many seeds, includes dormant seed in the total germination figures.Â
           Storing these seed at near room temperature for 12 to 18 months after harvest will often break dormancy in many of the seed. To obtain a more realistic test of germination that is, seed which will germinate under favorable temperatures, within 28 days of planting, a farmer should run his own test and discount those seed that do not germinate within 28 days (practically all non dormant seeds will germinate in 14 days).
          Â
           To test without the “pre-chilling”, put 200-400 seeds on a damp paper towel, place paper towel containing the seed in a sealed plastic container (rag doll test) and keep at room temperature (70-85oF) for two weeks. If germination is less than 50% of that stated on the tag, you may want to hold these seeds over and plant next year. If holding over seeds, store in normal, acceptable conditions and re-test (both officially and rag doll) before planting next year.
class=Section2> Â
 Seeding:
Â
           6-10 lbs/A of pure live seed (PLS)
           PLS = % Germination x % purity
           Seeds are usually sold on PLS basis.
 When soil temperature is 55 oF or higher.
           Best:               April 1 – May 7
           Possible:         March 1 – June 30
Planting Method:
Â
           Switchgrass may be planted into a previous crop stubble a sod or into a fallow area on a prepared seedbed.Â
           No-till planting: A good practice for establishing switchgrass is to no-till plant into an undisturbed sod or stubble to avoid excessive competition from annual weeds. For no-till planting use a drill and makes a furrow 3/4 to 1″ deep. After a rain the seed will be mostly covered with 1/2 to 3/4″ of soil. Successful no-till seedings may be made in April or May into a stubble of winter rye, or wheat, or into a previously tilled sod of tall fescue. However, some stand reductions have been encountered when planting into rye, wheat or fescue in recent years, and it is believed to be due to chemical constituents of the stubble crop that reduces seedling emergence and vigor of switchgrass seedlings (or allelopathy).
           To reduce this problem and other problems associated with too much residue, rye, wheat or tall fescue should be clipped or grazed to about a 4″ height prior to killing with Gramoxone or Roundup. Rye or wheat should be killed at least 4 to 6 weeks prior to planting, and ideally tall fescue should be killed in October prior to April or May plantings. An additional spraying of herbicide may be necessary in early spring to kill winter annual weeds. Killed mulches over 12 inches tall have proven disadvantageous in most cases for March, April or May plantings. Planting switchgrass in June into standing stubbles of wheat or rye 6 to 12″ in height have often been successful due to moisture conservation at the ground surface when temperatures are high.
           Another no-till procedure that should prove satisfactory is to seed switchgrass following a previous year crop of millet or sorghum. The millet or sorghum should be grazed or mowed to a 6″ stubble in late fall and permit frost to kill the stubble growth. Broadcast planting or closely drilled rows (10″ or less) of the millet or sorghum should prove satisfactory.
           Do not plant into common bermudagrass or dallisgrass unless they are completely killed, as they prove extremely competitive toward switchgrass seedlings.
           Fallow Planting: When erosion is not a major problem or there is moderate winter cover from dead crabgrass or other grasses, successful establishment of switchgrass in April and May has been made with minimum weed competition. One example is to leave the soil undisturbed following a wheat crop until the following spring.
           Prepared Seedbeds: Be sure soil is firm in order to plant seeds at 1/2″ to 1″ in depth. Two of the major problems with prepared seedbeds are: Increased weed competition, particularly crabgrass and foxtail and increased soil erosion. If crabgrass and similar weed populations are known to be low, switchgrass may be successfully planted on firm prepared seedbeds. Shallow drilling (3/4 to 1″) has often proved superior to cultipacker planting.
Managing Seedlings:
Â
           It is sometimes said that one should plant a field of switchgrass and not look at the stand until the following year. That advise indicates that grassy weeds often appear to be doing more harm than they actually are (if switchgrass emerges). If grassy weeds are very competitive, some selective and controlled grazing can be helpful. Switchgrass seedlings can tolerate only moderate defoliation in the seeding year prior to seed formation. However, grazing the weeds down rapidly followed by several weeks rest can prove helpful.
           It would be best to let the first growth go to full seedhead stage (seed in dough stage) before grazing or cutting for hay. The key is not to use much N (about 30 to 40 lbs. when seedlings are 6 to 8″ tall). Do not apply N at planting to minimize competition from weeds. Apparently, switchgrass seedlings can become established on low N levels.
           Grazing: Growth will begin early (April). Switchgrass has been grazed in several ways. For continuous grazing initiate grazing as soon as growth reaches 6-8 inches. Try to keep height of grazing between 5-10 inches because this helps prevent lower stem bases from becoming woody and stiff. Do not graze stubble below 4 inches. By July-August it will be necessary to let the stand rest long enough to reach 6-10 inches growth between grazings.
           If rotational grazing is practiced, begin grazing when 18 to 24 inches tall and graze to a 6 to 8 inch stubble in 7 to 10 days. Some growth is desirable (8-10 inches) for winter cover.
           Hay: In seeding year the first cutting should be made after seed heads have emerged and fully developed (seed in milk-dough stage). Leave about 4-6 inches of stubble when cutting for hay. In subsequent years take the first cutting when plants are between head emergence and full bloom (usually in June). A second cut can be made in 7-10 weeks. Let the third regrowth accumulate until after it has turned brown from frost. It is desirable to have 8-10 inches residue for winter cover, which should be burned the following February.
Fertilization:
Â
           Since there are no soil test recommendations from NCDA Lab for switchgrass, request a test report for bermudagrass. However do not follow the N recommendation for bermuda. As a rule, switchgrass produces more growth with less N than bermudagrass. When seedlings are 6 to 8 inches tall use no more than 30-40 lbs. N/acre so that weeds won’t be so competitive.
           For maintaining stands apply N, P, K in March after burning. Apply 50-75 lbs N/acre for early spring growth, but there probably is no need to use more than 100-150 lbs. N/A/year. After the early spring application, apply the balance in June or July. The phosphate and potash applications should be reduced relative to bermuda, but try to maintain a 4:1:2 ratio of N:P2O5:K2O. This ratio results in about 40 lbs. P2O5 and 80 K2O/acre when 150 lbs N/acre is applied annually.
class=Section5> Â
Priority:
Â
           Since switchgrass is such a high quality grass and most people will have a limited acreage, it is best to put priority on its use as follows: (1) stocker or growing animals, (2) milking dairy cows,(3) females ready for breeding or, (4) creep graze for calves.
 Research Results:
          Â
           The following three tables will give you some ideas about the initiation of growth, quality analysis, and animal performance of switchgrass compared to fescue, coastal, and flaccidgrass. (Source: Burns, Mochrie, Timothy, NCSU).
|
                 Species |
Date Grazing Began |
| Tall Fescue | April 7 |
| Switchgrass | April 21 |
| Flaccidgrass | May 3 |
| Coastal Bermuda | May 30 |
Table 2.   Average daily gain of 500-700 lb steers grazing several forages. 3-year average, Raleigh, North Carolina.
|
Species     |
April 7-May 30 |
May 30-Sept 18 |
Season Total |
|
Gain, lbs/day |
|||
| Tall Fescue (TF) |
2.04 |
– |
– |
| Coastal (C) |
– |
.92 |
– |
| TF + C |
– |
– |
1.27 |
| Flaccidgrass |
2.97 |
1.69 |
1.98 |
| Switchgrass |
2.37 |
2.02 |
2.11 |
Table 3.   Some quality characteristics* of perennial forages.
|
April 7 – May 30 |
May 30-Sept. 18 |
| Species |
Height (inches) |
IVDMD |
C.Protein (%) |
Height (inches) |
IVDMD |
C. Protein (%) |
| Fescue |
4 |
61 |
19 |
not grazed |
not grazed |
not grazed |
| Coastal |
not grazed |
not grazed |
not grazed |
3 |
56 |
19 |
| Flaccidgrass |
6 |
74 |
22 |
6 |
56 |
19 |
| Switchgrass |
6 |
72 |
17 |
7 |
61 |
15 |
                                          Â
*IVDMD and crude protein determined on canopy sample and not animal diet.
The following data were taken from Official Variety Test Reports. Harvest made with a mower and simulated hay management; yields under grazing would be less.
Â
Table 4.             Average hay yields (12% moisture) of perennial warm season grasses receiving 150-200 lbs N/acre/year. Forage Variety Testing Reports for four counties.
|  |  Rockingham              Rowan            Washington                  Wake |
|||||||||
| 1980-85 |
1980-85 |
1982-85 |
1984-89 1989 |
|||||||
| ——————————————-Tons/Acre————————————- |
||||||||||
| Coastal bermuda |
4.9 |
 | 4.81 |
 | 5.3 ¼br /> |  | - |
¼br /> |  - |
¼br /> |
| Tifton 44 bermuda |
 | 5.5 |
 | 5.8 |
 | 5.0 |
 | 6.3 |
 | 5.4 |
| Pasto-Rico bermuda |
 |  - |
 |  - |
 |  - |
 | 5.6 |
 | 4.9 |
| Tifton 78 bermuda |
 |  - |
 |  - |
 |  - |
 | 4.7 |
 | 4.8 |
| Midland bermuda |
 | 4.8 |
 |  - |
 |  - |
 |  - |
 |  - |
| Flaccidgrass |
 | 4.6 |
 | 5.6 |
 | 4.7 |
 | 6.1 |
 | 4.1 |
| Switchgrass |
 |  - |
 |  - |
 | 5.4 |
 | 4.7 |
 | 5.5 |
| Plains bluestem2 ¼br /> |  |  |  - |
 | 5.5 |
 | 5.4 |
 | 4.2 |
 |
| Caucasian bluestem2 |
- |
 - |
 |  - |
 |  - |
 | 5.9 |
 | 5.5 |
| Pensacola bahia¼br /> | - |
 |  - |
 | 3.6 |
 |  - |
 |  - |
 |
1 Yielded only 1300 lbs in 1984 and was 95% winter killed and was not harvested in  1985.
2 Severe winter-kill occurred in 1989-90 (>75% die back).
Â
Prepared by :¼br />  J.T. Green, Jr., J.P. Mueller Jr, .D.S. Chamblee, J.C. Burns: Feb 2005.