Quality Seeds

by John Squire, CCA

Each year presents new opportunities and new challenges for crop producers and this season has been
difficult or frustrating in a couple of ways. In the upper Midwest this spring was exceptionally wet and
generally cooler than average. Producers were not able to plant corn and soybean crops in a timely fashion
due to consistent rain patterns. In many cases, corn and soybeans were planted later than normal, very late, or
-in some cases- not at all. Where no corn or soybean crop was planted, the question becomes, "What to do
with the land?" Should one leave the land go to weeds, should one plant a cover crop, or fallow the land?
Why not summer seed alfalfa to those areas that were not planted to corn or soybeans?

Alfalfa is the fourth most widely grown crop in the United States with an estimated value of $8.1 billion per
year. Alfalfa is adapted to growing across a wide range of environments and can serve to provide a
significant amount of biological nitrogen to a following crop such as corn. Even in the heart of corn and
soybean country, fields of alfalfa can be found. Such fields help spread the workload throughout the year
instead of funneling it all to the spring or fall. The national average alfalfa yield is about 3.3 tons per acre per
year. At $100 dollars a ton and low input costs (purchase seed once for a 3-4 year stand and no nitrogen
fertilizer), coupled with nitrogen credits from 100 to 150 lbs. to a following crop, make this an attractive
enterprise to the farm. Additionally, alfalfa could serve very well as a stabilizing crop in filter strips along
waterways that border corn and soybean fields. Deep rooted alfalfa can extract nutrients and some less
desirable elements that leave row crop fields reduce the risk of ground/surface water contamination. The list
of values of alfalfa continues, but we will leave it there.

When choosing to plant alfalfa in the summer there are a few points to consider. There are both advantages
and disadvantages to planting alfalfa in the summer. A couple obvious advantages include; reduced workload
in the spring planting season, generally lower weed pressure occurs after a summer cultivation, and a chance
to harvest winter wheat before planting alfalfa. On the flip side, potato leafhoppers can severely suppress
alfalfa growth and establishment with summer seeding practices.

Fertility and seedbed preparation

Take a soil sample to test the level of nutrients available to the alfalfa crop. Key points for soil fertility with
alfalfa include potassium (K) levels, proper pH (between 6.5 and 6.9), and some micronutrients such as
boron, sulfur, calcium and zinc. A soil test will reveal any deficiencies that would limit alfalfa growth. The
best time to take a soil test for alfalfa is 6 months to a year before planting the crop. This provides time to
apply lime and give it time to react with the soil to neutralize the pH before planting the alfalfa. If a field of
alfalfa is already established and needs lime a topdress application may help raise the pH. Surface applying
lime is not as effective because it needs incorporation to neutralize a deeper soil profile.

Preparing the soil in the summer can be challenging due to dry soil conditions, which may lead to cloddy
seedbeds. Some producers choose to no-till plant alfalfa without working the soil. If using conventional
tillage to prepare the seedbed, the surface should be granular texture and not too cloddy, or too powdery for
proper seed to soil contact. Remember that alfalfa is a small seed and rough soils generally do not support
germination as well as a finer soil. The soil should firm before planting the alfalfa, firm enough that the heal
of your boot does not sink more than 3/8 inch.

When should I summer seed?

There are a couple of matters to consider when deciding on when to summer seed the alfalfa Moisture is
vital to seed germination and growth. Planting into moist soils is ideal, but planting into dry soils when a
desirable rainstorm in eminent will also insure that the seed will germinate. The second issue in summer
seeding is having enough time to allow adequate plant growth before a killing frost. More effectively stated
would be to have enough growth before the season turns cool enough to slow the growth of alfalfa. This date
varies depending on where you live. For the northern half of Minnesota , Wisconsin , and Michigan the time
would be before the middle of August. For areas south of that perhaps as late as the end of August or late
would still be just fine. The key to deciding how late to plant alfalfa is to know when the first average fall
killing frost in your area is. Alfalfa needs six weeks after emergence to grow before a killing frost in the fall.
Another way to look at this is to back up 7 or 8 weeks (to allow for germination) before a killing frost to
make the cutoff for planting. LG 9326, LG 9429, and Awesome all have good winter hardiness and are
adapted to summer or spring seeding.

Seeding adjustments

Many times producers spend little time calibrating their planter. They figure little changed since the last time
they used it and everything should be set for the correct lbs. per acre. Alfalfa seed size may not seem to vary
any but different seed lots may vary in the way they flow through the planter. This make it important to
check your planter seeding rate (calibrate the planter) for each alfalfa variety or treatment you use. To do
this, collect and weigh the seed dropped from the planter for a measured distance. Then calculate the area
covered by the planter in that distance. Convert the area to a fraction of an acre and multiply the seed weight
by the number of times that area fits into an acre. - Example: you collected 1/4 lbs. when the planter traveled
50 ft and the planter is 12 ft wide. => 50x12=600, 600÷43560=0.013774, 1÷0.013774=72.6 72.6x0.25=18.
The calibrated seeding rate is 18 lbs. per acre.- Dan Undersander (Seeding Rate of Different Alfalfa Seed
Lots - Agr. Advice FC 12.2.1 Aug. 1999) reported differences in seeding rates of various seed lots and
planters ranging up to 7 lbs. per acre. At $4/lb. retail this could mean a difference of 28 dollars an acre in
seed expenses.

People who seed alfalfa regularly understand the importance of proper planter settings. Two common
methods of seeding alfalfa are to use a drill with a small seed box for alfalfa, or to use a culti-packer type
seeder. Alfalfa should be seeded between 1/4 to 1/2 inch deep, in medium textured soil and from 1/2 to 1
inch on sandy soils. Also, soil moisture should be considered in deciding planting depth to optimize
germination and growth. Seeding rate varies by soil type and farmer preference, ranging from 10 to 24 lbs.
alfalfa seed per acre. Common rates range from 14 to 20 and the target population of seedlings per square
foot is 30. This will easily decrease to 15 or 20 plants per square foot after the first winter. When planting
into fields that have not had alfalfa in them for 3 to 5 years one should inoculate the alfalfa to promote
nodulation for nitrogen fixation.

Pest control

Summer seeding alfalfa is beneficial for weed control since many weeds have germinated in the spring and
cultivation will kill many existing weeds. Some weed seeds will germinate in the summer but generally weed
pressure will be less than spring seeded alfalfa. The critical weed control period for alfalfa is the
establishment year. This is the time when weeds most easily diminish alfalfa stands and ultimately reduce
yields. One method of weed control during establishment is to cut the alfalfa before the weeds interfere too
much. This works effectively in some cases but other instances may warrant the use of herbicides. If using a
herbicide read and follow the label for proper application rate and timing. Weed control throughout the rest
of the stand life is generally not an issue.

Potato leafhopper control is critical when summer seeding (spring seeding as well) alfalfa. Set-backs from
potato leafhopper during the seeding year can persist the life of the stand. Scout alfalfa fields weekly to
determine the level of leafhopper infestation. Spray to control leafhoppers when thresholds are found. Even
though spraying to control this pest may seem expensive and time consuming, it will pay with higher yields in
the current season and in those to come.