FORAGE YIELD AND QUALITY OF 6 ANNUAL MEDICAGO SPECIES IN THE NORTH-CENTRAL USA

Annual medics (Medicago spp.) have been extensively used as winter ann ual forage and green manure crops in Mediterranean regions, but their potential use in the north-central USA has not been evaluated. Our obj ective was to determine the summer and fail forage yield and forage qu ality of spring- and summer-seeded annual medics. Twelve commercial an nual medic cultivars from Australia (representing five species) and 'G eorge' black medic (M. lupulina L.), 'Nitro' alfalfa (M. sativa L.), a nd 'Arlington' red clover (Trifolium pratense L.) were seeded in sprin g and summer at Rosemount and Morris, MN, in 1991 and at St. Paul and Pecker, MN, in 1992. Forage yields were taken at a single harvest in s ummer (when most medics were reproductive) from spring-seeded stands a nd in the fall first frost (0 degrees C) from summer-seeded stands. Fo rage yields of spring and summer-seeded annual medics ranged from 1.2 to 5.7 and 0.5 to 5.5 Mg ha(-1), respectively, depending on location a nd species. Barrel medic (M. truncatula Gaertn.), snail medic [M. scut ellata (L.) Mill.], and burr medic (M. polymorpha L.) cultivars were a mong the highest yielding, while Nitro alfalfa, George black medic, an d Arlington red clover were consistently among the lowest yielding for age species. George black medic, Harbinger strand medic (M. littoralis Rohde ex Loisel.), and Kelson snail medic were among the highest in f orage crude protein (CP) concentration for both summer and fall harves ts. Forage fiber concentrations of all annual medics except Sava snail medic were equal to or lower than those in Nitro alfalfa. Our results indicate that annual medics have the potential for producing high yie lds of quality forage in the north-central USA and might be used as sh ort-season annual crops for harvest in fall and summer when traditiona l forage supplies are inadequate.