Alfalfa (Medicago sativa) is a widely cultivated perennial legume valued globally as a premier forage crop. Its deep root system and ability to fix atmospheric nitrogen make it high-yielding, especially when managed for hay production. Alfalfa is highly sought after for livestock, particularly dairy cattle and horses, due to its high crude protein content and digestible energy. Achieving high-quality alfalfa hay requires careful attention to specific growth stages and harvesting techniques, from preparing the soil to curing the final product.
Site Preparation and Soil Requirements
Alfalfa thrives in soils with a near-neutral to slightly alkaline pH, ideally ranging between 6.5 and 7.5. Soil testing is necessary to determine the current pH level, as acidity below 6.2 significantly reduces alfalfa yield and nutrient uptake. If the soil is too acidic, agricultural lime must be incorporated several months before planting to raise the pH.
Proper soil drainage is equally important for long-term stand health because alfalfa roots are highly sensitive to saturated conditions, often referred to as “wet feet.” Fields with poor internal drainage or a shallow water table should be avoided, as prolonged waterlogging can lead to root rot diseases like Phytophthora. Selecting a well-drained loam or clay-loam soil is the preferred approach for establishing a productive field.
A baseline soil test measures existing nutrient levels, focusing on phosphorus (P) and potassium (K). These macronutrients do not move easily in the soil, so they must be incorporated or applied before seeding for optimal root access. Adequate P supports root development and nodulation, while K plays a significant role in overall plant health, winter hardiness, and yield.
Soil tests provide specific recommendations for P and K application rates, ensuring the young plants have the necessary resources to develop a deep, robust root system before the first harvest.
Seeding and Establishment
Once soil conditions are optimized, growers typically choose between early spring planting or late summer/early fall planting, depending on regional climate and weed pressure. Spring seeding allows for growth throughout the first season but requires more aggressive weed management due to competition.
Late summer planting, six to eight weeks before the first hard frost, offers less weed competition and allows the stand to establish a strong root system before winter dormancy. Alfalfa seeds must be treated with the correct strain of Rhizobium meliloti bacteria before planting. This inoculation enables the plant to form root nodules and convert atmospheric nitrogen into a usable form (nitrogen fixation).
Seeding rates generally range from 15 to 20 pounds of pure live seed per acre. The depth of planting is important for successful germination; seeds should be placed shallowly, typically between 1/4 and 1/2 inch deep. Planting too deep can deplete the seed’s energy reserves before the seedling reaches the surface.
Managing weeds during establishment is a primary concern because young alfalfa plants are poor competitors for light, water, and nutrients. Pre-plant incorporated herbicides or post-emergence control measures are often necessary. Effective initial weed control sets the field up for multiple years of clean, high-quality hay production.
Stand Management and Longevity
Maintaining a high-yielding alfalfa stand requires a proactive approach to nutrient replacement and pest management. Alfalfa is a heavy feeder of potassium (K), and repeated harvests remove substantial amounts of this nutrient. Maintenance fertilization involves regular applications of P and K, often after the second or third cutting, to replace the nutrients extracted by the harvested biomass.
Potassium supports the plant’s physiological functions, including water regulation and disease resistance, and is particularly important for rebuilding carbohydrate reserves before winter. Regular soil testing, perhaps every two to three years, guides these maintenance applications, ensuring nutrient levels support maximum yield without wasteful over-application.
Water availability significantly impacts alfalfa yield, especially during active growth between cuttings. While deep-rooted plants access water deeper in the soil profile, supplemental irrigation may be necessary in drier climates or during extended droughts. Adequate moisture ensures the plant can rapidly regrow after harvest and maximize its seasonal yield potential.
Monitoring for insect pests, such as the alfalfa weevil and the potato leafhopper, prevents significant yield losses. The alfalfa weevil larvae feed on new growth in the spring. The potato leafhopper causes a characteristic yellowing, called “hopper burn,” which reduces forage quality. Scouting the field and using established economic thresholds helps determine when pesticide application is warranted.
Preparing the stand for winter dormancy directly impacts stand longevity. The timing of the final autumn cutting is adjusted to allow plants sufficient time to accumulate carbohydrate reserves in the crown and roots before the first hard frost. This energy accumulation ensures the plants survive the winter and initiates vigorous regrowth the following spring, extending the productive life of the stand.
Harvesting and Curing for Hay Quality
The moment of harvest is the biggest determinant of final hay quality, balancing the goals of high yield and high protein content. For the best blend of quality and quantity, alfalfa is typically harvested at the late bud to 1/10th bloom stage. Cutting earlier maximizes protein and digestibility but reduces tonnage, while cutting later increases tonnage but reduces nutritional value.
Hay quality is often measured by Relative Feed Value (RFV) or Relative Forage Quality (RFQ), indices that relate to the digestibility and nutrient concentration of the forage. Cutting height also affects regrowth potential and stand health. Leaving a stubble height of three to four inches ensures enough leaf area remains on the plant to quickly initiate photosynthesis and regrowth.
After cutting, the curing process begins, aiming to rapidly reduce the moisture content of the cut forage. Alfalfa is typically wilted in the field until it reaches a moisture content safe for baling, generally below 18 percent. This wilting is managed using mechanical conditioning, which cracks the stems to allow moisture to escape at a rate closer to that of the leaves.
Raking the windrows is performed when the hay is partially dry (30 to 40 percent moisture) to speed up drying and prevent excessive leaf shatter. Alfalfa leaves contain the majority of the protein and are easily lost if handled when too dry. Baling the hay once moisture content is confirmed to be below the safe threshold prevents the growth of molds and fungi, which can reduce quality and pose a risk of spontaneous combustion in storage. Protecting the finished bales from rain and ground moisture in a covered structure preserves the nutrient value.