Establishment of Temperate Pasture Species into Alfalfa by Frost‐Seeding

Abstract

Mature alfalfa (Medicago sativa L.) stands are generally unsuitable as pastures because of their low plant density and the relative inability of alfalfa plants to tolerate grazing pressure. The objective of this research was to determine the potential for introducing new species into mature or declining alfalfa stands by frost‐seeding. Experiments were conducted in 1995 and 1996 at the University of Wisconsin Agricultural Research Stations near Arlington, WI (four sites), and Lancaster, WI (three sites). Smooth bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), perennial ryegrass (Lolium perenne L.), reed canarygrass (Phalaris arundinacea L.), timothy (Phleum pratense L.), and red clover (Trifolium pratense L.) were frost‐seeded into mature alfalfa stands at seeding rates of 0, 55, 110, 220, 440, and 880 seeds m−2. Competition from existing vegetation was reduced by clipping the fields in the autumn prior to seeding and harvesting (by either grazing or clipping) during the seeding year. Seedling counts were taken approximately 60 and 90 d after seeding. Seedling densities were similar at 60 and 90 d after seeding in both years. There was variability in the magnitude of species establishment and density among sites, but species ranking order was fairly consistent across sites. Species ranking for seedling density was perennial ryegrass > orchardgrass, smooth bromegrass, and red clover > timothy and reed canarygrass (59, 28, 20, 22, 13, and 5 seedlings m−2, respectively). All species showed a linear or quadratic response to increasing seeding rate, but the response varied with species. Results of this research indicate that establishment of these species by frost‐seeding is possible and that this technique can increase plant diversity within pastures.