Sod-Seeded Soybeans for Forage

The availability of quality forage in the mid-summer often limits livestock production in the southern U.S. Corn Belt. Soybeans [Glycine max (L.) Merr.] sod-seeded into grass pastures may give farmers a chance to improve the quantity and quality of forage available for grazing. The objectives of this study were to examine the growth and development patterns of four soybean cultivars grown in grass sod and to determine the potential of sod-seeded soybeans for forage. The cultivars PI 89003-1 (Group II), ‘Williams’ (Group III), ‘Bobwhite’ (Group V), and ‘Hill’ (Group V) were seeded on 18 June into a tall fescue (Festuca arundinacea Schreb.) sod with and without paraquat (1,1'-dimethyl-4,4'-bipyridinium ion) at 0.57 kg(ai)/ha. Paraquat was used in this research to suppress the tall fescue sod. Total forage (soybeans plus grass) yields ranged from 6,700 kg/ha for Hill, sprayed with paraquat, to 4,500 kg/ha for Williams unsprayed. The crude protein (CP) content at frost ranged from 15 to 18%, and the in vitro dry matter disappearance (IVDMD) averaged about 60%. Tall fescue grown alone produced 2,800 kg/ha dry matter with 50% IVDMD and 8 to 10% CP. Dry matter accumulation of soybeans was affected by paraquat and the duration of constant growth rate. During the constant growth rate phase, plots sprayed with paraquat produced about 75 kg/ha·day of dry matter, whereas unsprayed plots produced about 50 kg/ha·day. Duration of constant growth rate increased with tune to maturity except for the viney-type Bobwhite, which had a shorter constant growth rate phase than expected. Late-maturing soybean cultivars appear better for use as a forage because they offer greater flexibility as to time of harvest, maintain higher forage quality, and generally produce more forage than early-maturing soybeans. These results, based on a single season, indicate that soybeans can add to the quantity and quality of the forage available in tall fescue pastures.