Fall Seeding Alfalfa
While we are rapidly approaching the optimal time to begin fall seeding alfalfa, there’s still time to get the crop established before a killing frost. Newly-seeded alfalfa requires five to six weeks after seeding before a killing frost or freeze.
A major key to successful forage production is a good soil testing and fertilization program. It’s best to apply needed amendments to the soil prior to seeding establishment. If the soil analysis indicates a need for liming materials, apply agricultural lime in amounts called for by the soil test. If the soil will be tilled prior to seeding, till the lime into the soil.
Applying Lime Takes Time
If the seeding must be established no-till and the test calls for large quantities of lime (four or five tons per acre or more), care must be taken to not create a very high pH zone at the surface with a low pH zone just below. In this case, it might be best to apply the lime in equal annual amounts over a period of three or four years.
Phosphorus and potassium are the two most critical fertilizer materials for establishing and maintaining alfalfa stands. An initial application may be tilled into the soil prior to planting. Fertilizer must be top-dressed in succeeding years. Band application of a starter fertilizer at seeding time may help ensure stands on soils testing low or very low in phosphorus.
Get the Foundation Right for Planting
Preparing a firm seedbed for planting is essential. This can be accomplished by firming the soil with a corrugated roller or cultipacker before seeding. After seeding, firm the soil again to cover the seed and obtain necessary seed-soil contact. Final seed placement should be no deeper than ½-inch in heavy soils and ¾-inch in light soils.
If stands established in the spring are inadequate, they may be reseeded or inter-seeded the following late summer. For alfalfa, stand counts per square foot should be +25 for a good stand, 15 to 25 for a marginal stand, and less than 15 for a poor stand in the establishment year. Poor stands should probably be reseeded or inter-seeded.
Evaluating Stand Quality
The difficult decision comes with a stand of 10-15 plants per square foot, where, if the plants remain healthy, additional seeding and fertility operations under less-than-ideal conditions may damage the stand, ultimately doing more harm than good.
Under those circumstances, producers should consider weather and soil conditions carefully. Reseeding marginal stands largely depends on the producer’s immediate need for forage and the resulting management of the stand going into fall and winter. A reseeded or inter-seeded area would not be harvested after the seeding to improve the chances for good stand survival through the winter.
Interseeding a poor stand of newly-established alfalfa plants will likely be more successful than attempting to thicken an old, established alfalfa stand. In either case, the alfalfa stand achieved will probably not be uniformly thick.
Finally, a general rule of thumb is to plant 12-15 pounds per acre of high-quality seed per acre. Products like LH 9400 and LH 9120 BR are ideal choices to plant this fall and will provide years of high-quality forage.
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