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FIELD PREPARATION AND TIMING
- Test soil and apply corrective aglime, N, P205, K20 and micronutrients.
A proper pH is the single most important fertility factor for establishing
and maintaining high yielding, productive alfalfa stands. Apply
aglime at least 12 months before seeding to achieve a desired 6.7-6.9
pH at
seeding.
A pH of 6.0 verses a pH in the 6.7-6.9 range can reduce the
first hay year's first crop yield by 30%. This yield drag continues
for the life
of the stand.
- Control perennial weeds such as quack grass
before seeding.
- For Kussmaul Seeds marketing area, the spring seeding
of alfalfa seed can begin as soon as a proper seedbed can be prepared.
A proper seedbed is one that is smooth, firm, clod-free for the
optimum placement of
seed
by the drill or Brillion seeder. Avoid working soils that
are too wet to prevent compaction and crusting.
- Alfalfa stands can
also be established by summer seedings. Keys include timing seedings
with anticipated moisture
and early enough
in August
to allow 6-8" of growth before the first killing frost.
Seeding should be completed by August 10th in the northern
half of
Kussmaul Seeds
marketing area and by August 20th in the southern areas.
- A
seeding rate of 14-17 pounds of high quality alfalfa
seed will usually produce adequate stand counts. Go 20%
higher if direct seeding.
- Place seed 1/4 to 1/2 inches
deep on medium and heavy soils and 1/2 to a maximum of 1 inch on
sandy soils.
- Good alfalfa stands can be established with companion
crops if the field is managed to the advantage
of the alfalfa rather
than the companion
crop.
GERMINATION AND EMERGENCE
- Germination will begin after an
alfalfa seed has absorbed about 125% of its weight in water.
- Germination
will begin when soil temperatures exceed 36∞F. However,
the ideal temperature range for germination is 65-77∞F.
- Alfalfa seedlings are very cold tolerant through the first trifoliate
leaf stage of growth. The first trifoliate usually
develops about
two weeks after emergence.
- Under normal conditions, only
about 60% of the seeds planted germinate and emerge from the soil.
ESTABLISHMENT
(The period of time from emergence
to the appearance of the first flower buds. A period 6-8 weeks for
spring seedings and 9+ months
for summer seedings)
- Nearly 60-80% of the seedlings that emerge, disappear
during the first year.
- Alfalfa is particularly vulnerable to
these diseases during the seeding stage; aphanomyces root rot, Anthracnose,
common leaf
spot,
Downey
mildew, Phythium seedling rot, spring black stem and summer
black stem. Growers
can put the odds of a successful stand in their favor by planting
resistant varieties, using seed treated with the Apron fungicide
and following
recommended cultural practices.
- Seedling alfalfa, particularly
under a spring seeded companion crop, are a prime target for potato
leafhopper injury. Select
resistant varieties
or monitor fields for the presence of potato leafhoppers
and use chemical control as needed.
- Control competition from annual
and perennial weeds.
PRODUCTIVE MATURE
STANDS
- Alfalfa has a tremendous ability to produce maximum yield
over a wide range of stand densities. Normally, new seedings should enter
the
first
hay year with 25 to 30 plants per square foot.
- Alfalfa yield is determined
by the number of plants in a given area, the number of stems per
plant and the weight of each stem.
The maximum
number of stems on a plant is set within 14 days after harvest
and declines as
the plant ages.
- Maximum forage growth occurs when temperatures
are between 50 and 80∞F.
- The leaf to stem ratio is less for spring
growth than mid-summer. However, summer growth will have greater
lignification than spring
growth.
- When three harvests are taken during a growing season,
the relative yield rations are 7:5:3. That is, if the first crop
yields 3 T
/ A, then the second and third will yield approximately 2.1
and 1/3 T/A
respectively.
The relative yield ratio is generally 9:7:5:3 in a four cut
system.
- The selection of a cutting schedule is very important.
- For optimum
persistence cut between first flower and 25% flower for each crop.
Generally a three cut system.
- For high quality, cut at mid-bud and
28-33 day intervals thereafter. No after frost harvest. Usually a
four cut
system.
- For high yield and high quality, cut first
crop at the bud stage, the second in 28-30 days and subsequent
crops at 38
to 55 day intervals.
Generally
a four crop system.
- No harvest advised September-October
15th for any of the above cutting schedules.
- Each ton of alfalfa
hay harvested removes approximately 14 pounds of P20S, 58 pounds
of K1O; and the calcium
and magnesium found
in 100 pounds
of aglime. This is the nutrient equivalent of
150 pounds of
0-10-40 fertilizer. Replace annually with top
dressed mineral fertilizer
or manure when feasible.
- Disease pressure during
the early hay years of the rotation includes; anthracnose, common
leaf spot and
spring black
stem. Later in the
hay years Bacterial wilt, Fusarium wilt and
crown rot: and Verticillium wilt
join
the assault. For long stand life, plant resistant
varieties, maintain fertility and follow recommended
cultural
practices.
- Monitor alfalfa stands for alfalfa
weevil during May and June; and potato leafhopper
during June,
July and
early August.
Treat
as recommended.
- Typically, stands that fall
below 40 stems per square foot or 3 to 4 healthy plants
per square foot are no
longer profitable
and
should
be rotated.
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