Establishing Alfalfa-Grass Mixtures for the Midwest.

Adding grass to alfalfa grown for dairy has both agronomic and nutritional benefits. The purpose of this research was to seed different mixtures of alfalfa (Medicago Sativa) and three grass species to determine the emergence of alfalfa and grass in the seeded mixtures.

Three grass species (meadow fescue [Festuca pratensis], tall fescue [Festuca arundinacea] and orchardgrass [Dactylis glomerata]) were seeded with alfalfa at three locations in Wisconsin (UW Arlington, Lancaster, and Marshfield Research Stations) in 2010. Alfalfa was seeded at the rate of 645 seeds/m² with varying grass seeding rates as shown in the table. All seed lots had over 90% germination. Seedling emergence was based on plant counts taken 30 to 40 days after seeding.

Grass seeding rate of the grass had little effect on grass plant counts taken 30 to 40 days after seeding, ranging from 23% emergence at 15:85 grass:alfalfa to 19% emergence at 50:50 grass:alfalfa to 16% emergence at 75:25 grass:alfalfa.  Tall fescue and meadow fescue has similar emergence across the seeding mixtures (26 and 24%, respectively) while orchardgrass had lower emergence (9%).  Grass establishment was significantly higher at Lancaster than at the other two sites, suggesting a large environmental effect for establishment. 

Emergence of alfalfa was not affected by the grass seeding rate except at the very highest levels of grass seed.  Therefore higher grass seeding rates resulted in higher grass percentages in the final mixtures (see graph).  In general, as grass seeding rate increased, the alfalfa declined as a percent of the total stand.  It is also apparent that orchardgrass had less effect on alfalfa stand reduction than the other two species.  Seeding rate recommendations for mixtures will result in varying alfalfa-grass percentages depending on the grass species, seeding rate and environment during the seedling establishment phase.