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Boosting Forage Yields In Thin Alfalfa Stands


by Margaret Smith, PhD
Forage Agronomist

Were your alfalfa stands damaged over winter and thinned beyond optimum production potential?  Thin alfalfa stands can be interseeded with various other forage species to improve forage yield and extend their life span.

If your current alfalfa stands have experienced loss over the winter, assess the potential of that stand (check out our Assessing Alfalfa post). When counting alfalfa stems, over 55 per square foot is a ‘keeper‘ stand. If the counts fall between 40 and 55 stems per square foot, the forage performance may benefit from a boost from interseeding additional forages. With fewer than 39 stems per square foot, economic yields will definitely benefit from planting additional forage species.  

Interseeding legumes will maintain high quality forage. Interseeding grasses will increase forage yields; quality can be maintained through attention to grass growth stage for harvesting.

Options for Interseeding into Alfalfa

    Alfalfa is NOT recommended (with a limited exception)

    Because alfalfa is autotoxic to new alfalfa seedlings, attempting to thicken a stand with additional alfalfa is not a good option. The exception is for a stand established only last year. One-year-old alfalfa plants have not developed high levels of autotoxic compounds and farmers have reported success interseeding additional alfalfa in this planting window.

    Alternate Legumes

    • Red clover is the best alternate legume choice if planning to keep your forage stand for more than one year. Red clover dries somewhat slower in the windrow than alfalfa, so plant a variety like Freedom or Ruby Red, selected for faster drying. Seed at 6 pounds (drilled) to 10 pounds (broadcast)per acre.
    • Berseem clover is a good choice if only planning to keep your stand through this crop year. Berseem, an annual, begins growth quickly in the spring and continues actively through frost. Be sure to mow berseem before flowering to ensure regrowth. Flowering and low mowing will end berseem’s life cycle. Seed 7 pounds (drilled) to 12 pounds per acre (broadcast) per acre.


    • Orchardgrass or tall fescue are options when planning to retain your stand for more than one year. These perennials are slow to establish and, when planted in the spring, can benefit from an early first harvest to reduce competition and shading from established alfalfa. Once established, hay yields will outperform the older, pure alfalfa stand. Grasses don’t establish well when broadcast without incorporation. Drill at 5-10 pounds per acre for orchardgrass or 4 pounds per acre for fine-leaved, tall fescue. These perennials can also be interseeded in the late summer, when alfalfa growth and competition has slowed.
    • Italian ryegrass is a good choice for very high-quality, annual forage on soils with good water-holding capacity. As a winter-annual, Italian ryegrass will not set seed in the seeding year, so maintains high quality throughout the growing season. In the northern U.S., Italian ryegrass will winterkill. Drill 5 to 10 pounds per acre into established alfalfa. Select the higher rates with lower remaining alfalfa populations.
    • Spring small grains (oats, barley or triticale) also may be interseeded. These small grains may be used when alfalfa stands are very reduced and will be terminated after this growing season or after a single, late-spring or early-summer forage harvest. The small grains may be cut for hay or haylage. If cut in the boot stage, a warm-season forage can be seeded following. Drill 1 ½ to 2 ½ bushel per acre oats; 1 ½ to 2 bushel per acre barley; or 1 ½ bushel per acre triticale.

    Is It Time to Reseed Alfalfa?

    With very depleted alfalfa stands (fewer than 3 plants per square foot and/or fewer than 39 stems per square foot) it may be time to completely replace the stand. Optimum results with reseeding are with a full year of an alternate crop between hay stands. However, terminating a depleted alfalfa stand after a first cutting, either alone or with interseeded small grains, can also work.

    Following this forage harvest, terminate the alfalfa and seed a short-season corn for silage or warm-season-grass for additional forage production. Warm-season grass options include sorghum-sudangrass, forage sorghum, hybrid sudangrass, or one of several millet species. Terminating with tillage, followed by warm summer temperatures, adequate moisture, and growing grasses allow time and the environment for microbial activity which breaks down alfalfa’s autotoxic compounds. Breakdown of autotoxic  compounds is slower if alfalfa is chemically terminated and the following crop no-tilled and if conditions are very dry.  Alfalfa can then be reseeded the following spring.


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