Characteristics of Prairie Grass
Prairie grass (Bromus Wildenowii Kunth.) is a tall growing perennial
grass that is suited to well drained soils with medium to high fertility levels and a pH
of 6.0 or greater. It is a type of bromegrass, but is different from smooth bromegrass in
that it does not have rhizomes and it produces seed heads in each growth period,
especially during the summer. Herbage and immature seedheads of prairie grass are highly
palatable.
Prairie grass is more drought resistant and continues to grow later in the fall than most
cool-season forage grasses. Fall harvesting improves the winter persistence of prairie
grass. It will persist for 4 to 6 years in Pennsylvania if properly managed. It matures
about the same time or a little later in the spring than orchardgrass. Forage quality of
prairie grass compares well with other cool-season grasses but is more palatable. It is an
excellent grass for providing forage during droughts and for extending the grazing season
well into the fall in Pennsylvania.
Prairie grass is occasionally refered to as rescue grass (Bromus catharticus Vahl). While
these grasses are related, they are not the same and rescue grass is less persistent than
prairie grass in Pennsylvania's climate.
Adapted Prairie Grass Varieties
'Matua' is the only cultivar of prairie grass that is currently sold in the U.S.. This variety was developed in New Zealand under grazing conditions and has been very productive in Pennsylvania. Other prairie grass varieties are being evaluated by the USDA-Pasture Laboratory and Penn State University for persistence and productivity; however, none of these varieties are commercially marketed in Pennsylvania at this time.
Prairie grass is slower to emerge after seeding than either tall fescue
or smooth bromegrass. However, prairie grass growth and development after emergence is
greater than either of those grasses. A moist, firm seedbed is required for prairie grass
or prairie grass-legume mixtures. Spring or summer seeding of prairie grass are
recommended in Pennsylvania. However summer seedings should be completed by early August
in the northern half of the state and by mid August in the lower half of the state. Later
seedings are generally inadequately established to survive Pennsylvania winters.
Seed may be either drilled or broadcast. Drilling is preferred because it provides a more
uniform depth of planting. Plant prairie grass seeds 1/4 inch deep. Although prairie grass
seed sold in the United States has generally had the awn removed, the long fluffy seeds
often bridge in conventional seed drills and make planting difficult. Using one of the
alternate seeding methods listed will help reduce this problem: 1) mix prairie grass seed
with a small amount of triple superphosphate and sow through the fertilizer attachment of
the grain drill, or 2) mix prairie grass seed with a small amount of oats and sow through
the small grain attachment of your grain drill (only for spring seeding).
Most hopper-type fertilizer spreaders can be calibrated to broadcast prairie grass seed.
If seed is broadcast, however, be sure to lightly cover the seed with soil. This can be
done by light disking or by following with a drag or harrow. Unlike many other cool-season
grasses, prairie grass should not be cultipacked after seeding because it increases the
difficulty of seedling emergence and the risk of stand failure.
Prairie grass seeding rate varies with seedbed condition, method of seeding, and quality
of seed. Generally, when seeding prairie grass alone, rates of 30 to 35 lb per acre are
sufficient. When seeding in mixtures with a legume, seeding rates of 20 to 30 lb per acre
of prairie grass are recommended. Germination of stored seed can decline rapidly,
therefore seed should be used promptly and not stored from year to year.
Weed control at the time of seeding and during prairie grass establishment is extremely
important because of prairie grass's slow emergence and upright growth. The upright growth
allows emerging weeds below the prairie grass to receive sufficient sunlight to continue
growing. If weeds are anticipated (previous weed problem) in a field to be seeded to
prairie grass, use of a preplant or preemergence herbicide is recommended. Refer to the
most recent edition of the Penn State Agronomy Guide for efficacy and use restrictions of
herbicides labeled for use during and after forage grass establishment.
Prairie Grass Harvest Management
After spring seeding, prairie grass can be grazed after 50 to 70 days or
harvested for hay after 80 to 110 days, depending on climatic conditions. Grazing the
initial harvest after spring seeding will stimulate the formation and development of new
shoots. Even though prairie grass roots develop faster than smooth bromegrass or tall
fescue roots, make sure the grazing animals do not pull the young plants out of the
ground.
If the seedling growth of prairie grass is harvested for silage or hay, fewer new shoots
will develop and the stand will have reduced ground cover and a bunch type appearance.
Prairie grass yield from the first harvest after seeding will be similar to that from
smooth bromegrass but less than that from tall fescue. Grazing in the fall after a summer
seeding is not recommended.
In established prairie grass stands, delaying the first spring harvest will reduce
recovery rate and lower the yield potential of the next cutting. Under normal weather
conditions, about 25 to 30 days of regrowth is sufficient between harvests. This period is
a good balance between yield and quality of prairie grass. Generally, by this time new
shoots have developed at the base of the plant and harvesting or grazing will allow more
light to reach the shoots and stimulate their growth. A growth period of approximately 50
days in mid-summer will allow the prairie grass seed heads to mature and drop seed during
August. This will thicken up the stand the following year.
Prairie grass's ability to grow at cool temperatures makes it ideal for late fall or early
spring grazing. Fall yields of nearly 3.5 tons per acre are possible. It persists best
when managed so that monthly harvests are made during the fall. In addition, spring yield
and shoot density increase when multiple harvests are made in the fall. Harvesting only
once in the fall (November) caused 98 percent of the of the basal shoots (source for
growth the following spring) to winter kill. However, when prairie grass was harvested or
grazed 3 times during the fall only 35 percent of the basal shoots winter killed.
Compromise is needed with regard to fall harvesting because late fall grazing will
slightly reduce prairie grass vigor the following spring and restrict its use as an early
spring grazing source.
Prairie grass should not be cut or grazed below a 3 inch stubble height because regrowth
energy reserves and buds for plant regrowth are contained in this region. Cutting or
grazing below this height will weaken the plant and delay regrowth. Yields of nearly 7
tons per acre have been achieved when harvesting prairie grass for silage.
Prairie grass is an ideal grass for grazing systems because of its potential for early
spring and fall growth. Its spring growth offers the opportunity for earlier spring
grazing and its fall growth can effectively extend the grazing season by as much as two
months over traditional cool- season grass species. In addition, since seed heads are
palatable, it is not necessary to mow off the seed heads that remain after grazing.
Prairie grass persists better under rotational grazing than continuous grazing management.
It will not withstand overgrazing, especially when it is under stress of excessively wet
or dry conditions.
The quality of prairie grass is not as strongly affected by time of harvest as other
cool-season grasses. Digestible dry matter intake (DDMI) is greater for Matua prairie
grass than orchardgrass. When harvested on May 21, Matua had 25 percent greater DDMI than
orchardgrass. This difference increased to 35 percent when harvesting one week later.
Prairie grass may contain lower levels of trace elements than other grasses. Inclusion of
a legume in the mixture with prairie grass, or providing trace elements to animals
consuming primarily prairie grass will eliminate potential problems.
Fertility needs at seeding should be determined by soil test. Soil pH
between 6.0 and 7.0 is best for prairie grass, however it is adapted to slightly alkaline
or acid soils. In the absence of a soil test, assuming a medium-fertility soil, plow down
0- 45-135 lb. per acre and apply 20-20-20 lb. per acre at seeding (banded if possible). If
prairie grass is seeded with a legume, reduce or eliminate nitrogen application at
seeding.
Prairie grass requires a high level of fertility for maximum production. It is also very
responsive to N fertilization. If prairie grass is planted with alfalfa or another legume,
restrict annual N applications to 40 or 50 lb. per acre to limit the effect N has on
reducing nitrogen fixation of the legume. If prairie grass is grown without a legume,
apply 100 to 200 lbs N per acre in split applications of 50 lbs per acre in early spring
when the grass becomes green and 50 lbs per acre after each harvest and in early fall.
Adequate nitrogen fertilization is essential for maximizing prairie grass growth in the
fall.
Prairie grass is a deep-rooted grass which grows best on fertile, well-drained soils. It will provide early spring growth and excellent fall growth to extend the grazing season. Matua, the only variety of prairie grass currently sold in Pennsylvania, is a good cool-season grass for Pennsylvania conditions. However, proper management is essential to obtain adequate yield and persistence.
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This page was last updated on November 16, 2002