Ground Cover Potential of Forage Grass Cultivars Mixed with Alfalfa at Divergent Locations

Forage grass cultivars are often grown in binary mixtures with forage legumes. Because performance of grass-legume mixtures cannot be reliably predicted from pure stand information of the components, testing of grass-legume mixtures is necessary to develop reliable mixture recommendations. The objectives of this study were to evaluate a large number of cultivars of several temperate forage grasses in binary mixtures with alfalfa (Medicago sativa L.) for ground cover potential in a range of Wisconsin environments, and to develop an efficient cultivar screening program. Cultivars of nine species (146 total cultivars) were grown in at least one of five experiments. Experiments were seeded in spring of 1985 and 1986 at one of four locations divergent in both soil type and latitude. Grass persistence was determined after three growing seasons by evaluating the percentage of ground cover remaining. Grass species and genera varied in percentage ground cover, but were subject to interactions with years and locations. In general, orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) had the highest ground cover (76%). Variation in ground cover among cultivars was detected in all species except diploid perennial ryegrass (Lolium perenne L.), tetraploid intermediate ryegrass (L. hybridum), and festulolium (Festulolium braunii K.A.). Cultivars interacted with locations and/or years for all species, except reed canary grass (Phalaris arundinacea L.). Cultivar ✕ location interactions appeared partially due to latitude for smooth bromegrass (Bromus inermis Leyss.), tall fescue, and most ryegrasses, and to soil type for timothy (Phleum pratense L.). Conclusions regarding the development of a cultivar testing program differed for most species. A reasonable compromise in Wisconsin, to allow for testing each species in common trials, would be to select one southern and one northern test site.