26
Nebraska Farmer - June 2006
Hay/Forage
Manage your alfalfa
to get highest yields
By DAN UNDERSANDER
A
LFALFA management can mean the
difference between 3-ton or 6- to 8ton yields. Since fixed costs (land,
taxes, equipment depreciation, etc.)
remain the same and the difference
between harvesting a 1-ton and a 2-ton
yield is less than 10%, profit clearly relates to high yields.
Certain management practices can
lead to high yields of high-quality alfalfa, including:
■ Ensure optimum soil pH and
fertility. Yield declines dramatically
as soil pH falls below 6.8. Alfalfa needs
more potassium than most other crops.
Potassium must be supplied annually
in a single or split application to grow
high-quality forages. Other nutrients,
such as phosphorus, boron and sulfur,
can be supplied by either manure or
fertilizer.
■ Get good stand density. This is
often overlooked as farmers are trying
to get another year out of a stand, but
remember, when stand density falls
below 55 stems per square foot, the
stand is limiting yield. You would not
plant corn or soybeans at a low stand
density, so why keep a thin alfalfa stand
that is low-yielding?
■ Plant high-yielding varieties.
In 20 years of alfalfa variety trials conducted at several sites, University of
Wisconsin researchers have found the
average range in yield between the top
and bottom variety within each trial is
2.5 tons per acre per year. That difference would pay for the seed cost several times over for every year of the
stand.
■ Harvest on time. Since the first
cutting of alfalfa equals about 40% of
the total season yield and is often used
to refill silos for the milking herd, appropriate harvesttime is crucial. A key technique is to harvest first-cutting alfalfa
based on scissors-clip results reported
in the region or to use a forage-quality
stick. The optimum cutting date for
high-quality alfalfa can vary by as much
as two weeks from year to year.
■ Cut alfalfa short. Researchers
have found approximately a half-ton
yield increase for each inch shorter
alfalfa is cut, down to 1.5 inches. The
only reason to cut higher is if smooth
bromegrass or timothy is mixed with
the alfalfa; then, cut at 4 inches.
■ Make a wide swath. Hay in a
swath covering more than 80% of the
cut area will dry faster. Faster initial
drying will preserve more starches and
sugars through the curing process and
increase the total digestible nutrients,
or TDN, of the harvested forage.
■ Minimize ash content. Newer
forage analyses clearly point out the
loss that additional soil contamination
causes to hay value. Ash content of alfalfa and grasses is 6% to 8%. Each 1%
additional ash (soil contamination) is
1% less TDN. Average ash content of hay
and haylage samples submitted to the
University of Wisconsin Soil and Forage
Testing Laboratory is 10% to 12%.
■ Scout fields and spray. Alfalfa
weevil in some areas and years, and
potato leaf hopper in most areas and
years, can cause significant yield losses
if not controlled. This is particularly
true of new-seeding alfalfa where this
pest can stunt the crop so it will never
yield as well in future years — even if
the insect is not present.
■ Minimize driving on the field.
While some traffic is necessary for harvesting, each trip damages the stand
and reduces the next cutting’s yield.
First, minimize driving on the field by
eliminating unnecessary trips. Second,
reduce the effect of wheel traffic by
doing the driving on the field as quickly
as possible after cutting. Each day the
traffic occurs following cutting causes
an additional 4% to 6% yield loss from
the next cutting.
Alfalfa is a high-value crop that requires specific management practices
to produce high yields. High yields
result in greater profit since costs increase only minimally with high-yield
management.
Undersander is a University of Wisconsin Extension forage agronomist.
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