Article
Pasture Management
Through the Season
Sid Bosworth, Extension Associate Professor,
Department of Plant and Soil Science, University of Vermont sid.bosworth@uvm.edu
Spring Management
It is important to consider that what you do with
your pasture in the spring can determine what will happen for the rest
of the year in terms of pasture and animal productivity. Here are a few
things to consider that might help you improve pasture and animal performance.
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Start grazing on time. Spring is when grasses
have the highest growth rate during the year. If you start too late, the
animals will never catch up. A good rule of thumb is to start grazing when
the grasses reach about 3 inches in height if it is Kentucky bluegrass
or 4 inches in height if it is a tall grass like orchardgrass. Once your
animals have moved through the rotation, you can allow grazing to begin
when bluegrass reaches 5 to 6 inches or tall grasses, 7 to 10 inches.
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Adjust stocking rate so animals keep up with the
grass. Besides a high growth rate in the spring, grasses also have
the urge to produce a seed head. Once that process starts, your grasses
have definitely gotten away from you. The results can have a significant
negative impact on your pasture. Forage quality goes down. The pasture
is usually poorly utilized. Tillers that grow from the base of the sward
(the foundation for summer production) will be inhibited because of lack
of light. Legumes, such as clovers, are also inhibited to grow because
of competition by the tall, rank clumps of grass.
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The best way to control this is to have a stocking rate
that keeps up with the grass growth and inhibits or delays the grasses
ability to send up a seed head. Stocking rate is simply the number of animals
per acre grazing. In the spring, you might start with about one animal
unit (1000 lb cow) per half acre. In other words, a 30 cow herd would run
on about 15 acres in the spring. You may need to make adjustments from
this depending on the productivity of your pasture.
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If possible , divert the rest of your pasture area for
hay or silage. This means that you should put your worse ground into spring
grazing (that land that cannot be harvested). If you cannot divert half
of your pasture toward an hay harvest, you might consider adding additional
animals to your spring pasture program. This might include backgrounded
youngstock or stockers. Another option - make an arrangement with neighboring
dairy farmers to graze their dry cows and heifers during this period.
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Manage the pasture so that it is grazed at least
twice before June 1. This is easiest to do if you have a Voison type
rotational grazing system. By checking the regrowth of the earliest grazed
paddocks, you can decide when to start the second rotation. The rest of
the pasture that is ungrazed is then used for hay. If your animals are
grazing one large area, it is more difficult to monitor but a temporary
fence can be used to adjust stocking rate.
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Supplement with a magnesium mineral supplement to
prevent grass tetany. This is especially important for cows soon to
freshen or with calves at side that are grazing predominantly grass pasture.
Avoid fertilizing the pasture with potash or fertilizers containing potash
in early spring as this will make grasses more "tetany prone." If your
pasture has a significant amount of legume, it is much less likely to cause
a tetany problem.
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During the first week of grazing, slowly introduce
animals to pasture and supplement with some dry hay to avoid bloat.
This can be a problem when hungry animals quickly consume clovers, alfalfa
or even young, lush grass.
Summer Management
With adequate pasture available, most livestock
farms should be able to provide a relatively inexpensive feed during the
summer months. Only during periods of extended drought, should there be
a need to supplement cows with hay or silage. Here are a few things to
consider that might help you improve pasture and animal performance during
the summer months:
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Allow an adequate rest period between grazings
utilizing rotational grazing. Base this on the regrowth of the pasture,
not a certain number of days. In the summer months this may be anytime
between 25 and 40 days depending on weather conditions. In most pasture
systems, areas will vary in soil productivity, thus, pasture growth rates
will also vary. Therefore, it is best to not to use a set rotational
scheme but move animals to those paddocks that have reached their optimum
available pasture. Rule of thumb: allow grazing to begin when tall grasses
reach 6 to 7 inches in height or short grasses such a Kentucky bluegrass
when they reach 5 to 6 inches.
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Avoid overgrazing. Animals must be moved when
the available pasture falls below its optimum range or animal performance
will decline. As a rule, remove animals when grass heights are 2 to 3 inches
for tall grasses and 1 to 2 inches for bluegrass.
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Supplement if necessary. If pasture becomes short
during summer dry spells, it is often tempting to just let the animals
continue to move through the pastures eating what they can. If pasture
plants are eaten too often and too close, both plant production and animal
production will decline. When pasture becomes short, either supplement
with hay, haylage or increase pasture acreage.
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Forward creep graze your calves. Calves need
a higher quality pasture than brood cows. Utilizing a "creep" gate can
allow growing calves to graze the next fresh paddock and still return for
suckling, much the same principle as a creep grain feeder. Forward creep
grazing can also allow you to force the cows to clean up each paddock before
moving them, without jeopardizing the growth of the calves.
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Begin stockpiling pasture in late summer. If
you have additional pasture or hay ground, you can use this for late fall
grazing. Simply keep the animals off starting in mid- August. If the pasture
is primarily grass, you can increase it's productivity by applying approximately
50 lbs of nitrogen per acre (about 100 pounds of urea). Allow this pasture
to "stockpile" until your other pastures are completely grazed in the fall.
Then you can strip graze this pasture in late fall.
Fall Management
Although you can get significant forage during the
fall months, it is also a time of preparation for winter and the next year.
The following are some thoughts on managing in the fall.
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Soil test early in the fall to determine any
lime, phosphorus, potassium or magnesium needs. Fall is a good time to
do this and to apply most soil amendments.
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Manage your crops so that you reduce the risk of
winter injury. This will vary somewhat according to the particular
species.
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It is generally recommended to avoid grazing Timothy,
smooth bromegrass, red clover and birdsfoot trefoil from early September
to mid-October to allow for adequate accumulation of energy storage. A
late grazing after mid-October may be made, but only graze down to about
4 to 6 inches. This allows enough stubble to catch snow and protect the
basal portions of the plants.
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Other species such as orchardgrass, bluegrass, perennial
ryegrass, tall fescue or white clover are not as sensitive and can be grazed
throughout the fall months. These grasses can also tolerate a quicker rotation.
However, too short of a grazing or harvest interval can still deplete energy
reserves and weaken a stand. If the stand has been subjected to many grazings
through the year, it would be best to give it a longer rest period before
grazing.
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For alfalfa in Vermont, it is generally best not to
take a fall grazing or harvest. It reduces yield the following year and
increases the risk of winter injury. If you do harvest in the fall, be
sure there has been at least 45 days since the last cut and that your soil
potassium level is up to optimum on your soil test. If not, apply some
right after a late summer grazing or harvest while there is still time
for the plants to take some up before they go dormant. Also, leave 4 to
6 inches of stubble to help catch any snow during the winter.
This site is maintained by Sid.Bosworth@uvm.edu,
Plant & Soil Science Department, University of Vermont.
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Last modified May 26 2004 01:29 PM
