Alfalfa: Seeding Year Management
Seed alfalfa or alfalfa-grass mixtures only on well-drained soils. Seeding alfalfa following old alfalfa stands is not recommended, as this practice has led to stand establishment problems, which are thought to result in part from insect and disease buildup.
Have a soil test taken to determine lime and fertilizer needs for alfalfa establishment. Fields to be seeded to alfalfa should be limed to pH 6.5 to 7.0. Needed lime should be applied at least 6 months to a year before seeding to allow the lime time to react with the soil and minimize triazine herbicide carryover. For maximum production, seed only in soils that already are at a pH of 6.2. For soils below this pH, lime usually should be applied but seeding delayed. See Section 1.2 of this guide, Soil Fertility Management. Starter fertilizer applications of up to 20-60-20 per acre are desirable at seeding time. Band placement is highly recommended. Plant nutrients recommended in excess of this amount should be incorporated into the seedbed before seeding. If soil test recommendations are followed at planting, additional applications of fertilizer in the fall of the seeding year are not necessary. In absence of the soil test, refer to the typical plant nutrient recommendations listed in Table 1.2-5.
Alfalfa or alfalfa-grass mixtures may be seeded using conventional seeding equipment such as a cultipacker seeder or grain drill on a firm, well-prepared seedbed, or they may be seeded directly into corn stalk or small grain stubble using a special no-till seeder. No-till establishment requires special attention to weed and insect control, but if properly done it results in excellent stands with little or no soil losses. For specific recommendations, see “No-Till Forage Seeding,” below. Plant as soon as a good seedbed can be prepared in spring or, for a mid- to late summer seeding, in early to mid-August. Late summer seedings need at least 8 weeks of growth before the first killing frost.
Band seeding no deeper than ¼ inch is an excellent method of seeding. When band seeding or when using the no-till seeder, you may reduce recommended alfalfa seeding rates by one-third. Press wheels used in conjunction with conventional band seeding provide additional stand insurance. If the seedbed is dry and press wheels are not used, cultipack before and after seeding in the same direction as the band seeding, to ensure a firm seedbed. If annual crops such as oats or peas and triticale are used as a nurse crop, reduce the seeding rate of the companion crop by 30 percent, and harvest when the small grain is in the boot or early heading stage for silage, hay, or greenchop. Do not apply additional nitrogen for the nurse crop.
Fluid seeding—distributing seed in a carrier of water or fertilizer solution—is a new technique generally limited to forage legumes. Because fluid seeding requires special equipment for good seed suspension and distribution, custom application is recommended. Fluid seeding is a broadcast method, so for best results prepare the seedbed as in conventional seeding and cultipack after seeding.
Seeding rates necessary for successful stands are related to the condition of the seedbed and method of seeding. For suggested seeding rates, see Table 1.8-5.
Use preinoculated seed or treat seed with proper inoculant. If seed is preinoculated, look for the expiration date on the tag to see if reinoculation is necessary. This may occur if seed is not used soon after purchase or is stored improperly. Proper inoculation techniques are described in Agronomy Facts 11: Inoculation of Forage and Grain Legumes.
Seed that has been pretreated with Apron (metalaxyl) fungicide is available to give protection against Phytophthora and Pythium. These fungal diseases can cause serious establishment problems in poorly drained fields or following extended periods of heavy rainfall. Apron fungicide is available for self-treatment of seeds, also, and the fungicide Ridomil is available for soil application to protect against these same diseases.
When alfalfa is spring seeded, the first cutting can be made 60 days after emergence if one cutting during the seeding year is allowed to reach early bloom before it is harvested. Normally up to two to three harvests may be made in the year of a spring seeding, depending on the length of the growing season.