Alfalfa, or Medicago sativa, is a high-value perennial legume crop recognized globally as the “Queen of Forages.” This plant is primarily cultivated for its exceptional forage quality, offering livestock a rich source of protein and digestible fiber. The crop is also a significant component of sustainable agriculture due to its deep taproot system, which improves soil structure and enhances drought tolerance. Furthermore, alfalfa forms a symbiotic relationship with soil bacteria, allowing it to fix atmospheric nitrogen, which reduces the need for synthetic nitrogen fertilizers in subsequent crops. Establishing a successful, high-yielding alfalfa stand begins long before the seed is planted, demanding meticulous attention to soil conditions and planting technique.
Preparing the Seedbed
Successful alfalfa establishment requires creating an optimal soil environment, beginning with comprehensive soil testing. A soil sample should be taken 6 to 12 months before planting to accurately determine pH and nutrient levels, allowing time for necessary amendments to take effect. Alfalfa thrives in deep, well-drained soils and requires a near-neutral pH, ideally between 6.5 and 7.5, for maximum yield and nitrogen fixation. If the soil test indicates a pH below 6.5, agricultural lime must be applied and incorporated well in advance, as raising soil pH is a gradual process.
The physical condition of the seedbed is important, as alfalfa seedlings are poor competitors. Perennial weeds, such as quackgrass, must be controlled the season before seeding, since post-establishment control options are limited. Final seedbed preparation should result in a firm, yet fine, surface that is level and free of large clods. A common benchmark for firmness is the “footprint test,” where an adult’s heel should sink no more than 1/4 to 1/2 inch into the soil. This firmness prevents the small seeds from being planted too deeply and ensures good seed-to-soil contact, which is necessary for uniform germination.
Seed Selection and Inoculation
Choosing the appropriate alfalfa variety is a foundational decision for long-term productivity. Selection should be based on local climate adaptation, resistance to regional pests and diseases, and the intended use, such as hay production or grazing tolerance. Growers must consider the variety’s fall dormancy rating, which indicates how much the plant will slow its growth in the fall, a trait related to winter hardiness. Selecting varieties with high disease resistance index ratings is a proactive measure against common diseases like Phytophthora root rot.
The alfalfa plant relies on a symbiotic association with specific bacteria, Sinorhizobium meliloti, to convert atmospheric nitrogen into a usable form through nitrogen fixation in root nodules. Therefore, all alfalfa seed must be properly inoculated to ensure the bacteria are present at germination. While many seeds come pre-coated, the viability of the bacteria can decline over time, so the expiration date on the seed tag must be checked. If the seed is not pre-coated, or if it has been stored for an extended period, a fresh commercial inoculant must be applied just before planting.
Seeding Techniques and Timing
The timing of seeding is a choice between spring planting and late summer dormant planting. Spring seeding benefits from reliable moisture and allows for some yield in the first season, though it often faces intense competition from annual weeds. Late summer seeding, typically in August or early September, often avoids the heaviest weed pressure but requires consistent moisture to ensure establishment before the first hard freeze. Regardless of the season, seedlings must develop a minimum of three trifoliate leaves and a strong root system before a killing frost to survive the winter.
Alfalfa is a small-seeded crop, making the planting depth critical. The ideal depth is very shallow, usually between 1/4 and 1/2 inch in fine-textured soils, and no deeper than 3/4 inch even in sandy soils. Planting the seed deeper than one inch significantly reduces emergence rates and is a common cause of stand failure. The recommended seeding rate for a pure stand is 15 to 20 pounds of seed per acre when using a precision drill.
Drilling is the preferred method because it provides accurate control over planting depth and ensures uniform seed-to-soil contact. If broadcasting the seed, the rate should be increased by 10 to 25 percent to compensate for less uniform placement, and a cultipacker must be used to press the seed firmly into the soil. After planting, the soil surface should be rolled with a corrugated roller to firm the soil around the seed, which retains moisture and improves contact for rapid germination.
Initial Establishment Care
Management immediately following planting focuses on reducing competition and promoting deep root growth. Monitoring soil moisture is necessary, as alfalfa seedlings are sensitive to drought. If irrigation is used, it should be managed carefully to avoid waterlogging, which alfalfa does not tolerate, and to prevent soil crusting that can hinder seedling emergence.
Weed control during the first 60 days is crucial because weed competition stunts the slow-growing alfalfa seedlings. Post-emergence herbicides are commonly applied once the alfalfa plants have reached the second trifoliate leaf stage, providing enough leaf surface area to tolerate the chemical. For varieties with herbicide resistance, a product like glyphosate can be used, while conventional varieties require specific broadleaf and grass-selective herbicides.
Pest monitoring, particularly for insects like the potato leafhopper, should begin as soon as the seedlings emerge, as early infestations can severely damage the young stand. The timing of the first harvest is determined by the stand’s maturity. The first cutting should be delayed for approximately 60 days after emergence to allow the plant to develop a strong taproot and build up carbohydrate root reserves, ensuring long-term persistence and productivity.