Reagan L. Noland1, M. Scott Wells2, Krishona L. Martinson3, Roger L. Becker4 and Craig C. Sheaffer2, (1)Minnesota, University of Minnesota, Lindstrom, MN (2)Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN (3)Department of Animal Science, University of Minnesota, St. Paul, MN (4)Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN
Alfalfa winter-injury and winter-kill can contribute to significant losses, particularly in northern climates. Alternative warm season annual forage crops can be planted in response to winterkill, although appropriate species and best management practices need to be established. In 2014, eight warm-season forage options (brown-midrib sorghum (Sorghum bicolor), sudangrass (Sorghum bicolor subsp. drummondii), hybrid sorghum-sudangrass, annual ryegrass (Lolium multiflorum), Japanese milliet (Echinochloa esculenta), Italian rygrass (Lolium multiflorum), teff (Eragrotis tef), and annual rygrass with red clover (Trifolium pratense) were no-till planted into simulated, winter-killed alfalfa at the University of Minnesota Southern (Waseca, MN) and Rosemount (Rosemount, MN) Research and Outreach Centers. Three N fertilization rates (0, 56, and 112 kg ha-1) were applied as split-plots and harvests occurred on 30 day intervals (for three harvests total). In Rosemount, both species (P < 0.01) and N rate (P < 0.001) significantly affected forage yield. Teff (9.96 Mg ha-1), annual ryegrass, and annual ryegrass + red clover had significantly greater total forage yields than all other species. Brown-midrib sorghum and sudangrass were among the highest producing treatments at the first harvest, but did not regrow as well under the intensive cutting regiment. Despite any alfalfa nitrogen credit, treatments receiving 112 kg N ha-1 produced significantly greater dry matter than those receiving 56 kg N ha-1 which, in turn, resulted in greater yields than 0 kg N ha-1 treatments. Crude protein was also affected by both species (P < 0.001) and N rate (P < 0.001). Italian ryegrass had the greatest crude protein (14%), and treatments fertilized with either 56 or 112 kg N ha-1 resulted in significantly greater crude protein than unfertilized. NDFD (48 hr) was only affected by species (P < 0.001), in which case Italian ryegrass was significantly greater than all other species (76%). If managed as a supplement to an injured alfalfa stand, teff and the ryegrass options are most suitable for typical cutting cycles.