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New Crops News, Spring 1993, vol. 3 no. 1

Annual Medics: An Annual Forage Legume

Potential use of annual forage legumes as livestock feed or soil improvement crops in Indiana has not been adequately explored. Studies conducted by D.K. Greene, K.D. Johnson, and J.J. Valenec, and supported by Purdue's New Crops Center are underway to determine adaptation of winter-annual Medicago species commonly grown in Australia to the environmental conditions in Indiana when grown as summer annuals.

Fourteen cultivars representing five annual Medicago species ('Ascot', 'Cyprus', 'Mogul', 'Parabinga', Paraggio', 'Borung', 'Sephi' barrel clovers, 'Harbinger' strand clover, 'Kelson' and 'Sava' snail clovers, 'Paraponto' and 'Sapo' gama clovers, and 'Santiago' and 'Serena' burr clovers) were evaluated in a replicated trial at the Southwest Purdue Agriculture Center, Butlerville, and the Agronomy Research Center, West Lafayette in 1992. Also included in the trial for comparisons were a non-dormant alfalfa ('Sundor'), dormant alfalfa ('Vernal'), sweetclover ('Norgold'), and Korean lespedeza ('Common'). Each site was harvested twice for dry matter yield, and observations important to the potential success of these candidates were noted, including flowering characteristics, percent ground cover, senescence characteristics, seeding characteristics, and tolerance to pests. Subsamples were taken at each harvest and dried at 140deg.F. Medicago entries with superior agronomic potential, 'Vernal' alfalfa and sweetclover, were ground to pass a 3-mm screen, ground again with a cyclone grinder to pass a 1-mm screen, and analyzed for nitrogen content and in vitro dry matter digestibility.

Dry matter yields ranged form one-half to more than four tons of dry matter per acre in a single cutting (Table 1). Half of the medics screened increased dry matter yield at a second harvest of previously non-harvested forage. Reseeding was already apparent by late July for some Medicago species. Medic entries with most agronomic potential included 'Ascot', 'Borung', 'Mogul', 'Paraggio', and 'Sephi' barrel clovers and 'Kelson' snail clover. Nitrogen content was highest for sweetclover (3.15 percentage units) 'Kelson' snail clover had a significantly higher (P<0.01) nitrogen value (2.82 percentage units) when compared to other medic entries analyzed. Nitrogen content was lowest for 'Mogul' barrel clover (2.39 percentage units).

Medic entries with most potential, alfalfa, sweetclover, and red clover, will be further evaluated overseeded into a cool-season perennial grass or winter wheat in 1993.

Table 1. Dry matter yields of annual medic species, perennial alfalfa, and biennial sweetclover in Indiana, 1992.

                                             Yields (T/Acre)         
                                        West Lafayette   Butlerville    
                                       --------------  ----------------
        Species          Variety        July   August  July     August  
 M. trunculata (Barrel   Paraggio       1.77    3.63   2.18      3.52  
                         Parabinga      2.86    2.05   1.86      1.22  
                         Sephi          2.85    4.73   2.30      3.97  
                         Ascot          3.50    4.59   1.86      4.87  
                         Borung         3.37    3.74   3.07      3.58  
                         Cyprus         1.56    1.15   1.54      0.58  
                         Mogul          3.32    3.47   1.66      2.56  
 M. polymorpha (Burr     Serena         2.31    1.22   1.92      0.90  
                         Santiago       2.28    1.73   2.11      0.90  
 M. rugosa (Gama Clover) Paraponto      1.69    2.73   2.63      2.56  
                         Sapo           1.45    2.26   1.41      1.86  
 M. scutellata (Snail    Sava           2.30    2.37   2.82      1.79  
                         Kelson         2.27    4.79   4.42      5.06  
 M. littoralis (Strand   Harbinger      1.75    1.07   0.77      0.32  
 M. sativa (Alfalfa)     Sundor         1.90    2.16   1.28      1.54  
                         Vernal         1.90    2.56   0.90      2.05  
Melilotus spp.           Norgold        2.62    3.72   1.15      1.09