Performance of Forage Soybean in the Southern Great Plains

Pasture for livestock in the southern Great Plains is often in short supply during the late summer. This study compared seasonal patterns in forage production, forage quality, and seed yield of three recently developed forage soybean [Glycine max (L.) Merr.] cultivars (Donegal, Derry, and Tyrone) to the seed cultivar Hutcheson. Inoculated seeds were planted at 60 kg ha−1 in rows (20 m long) with 60‐cm spacing, in June 2001, 2002, and 2003, after harvest of no‐till winter wheat (Triticum aestivum L.). Whole plant samples were collected on six sample dates from approximately 52 to 120 d after seeding (DAS). At 120 DAS, forage soybeans Derry, Donegal, and Tyrone leaf and stem accumulations were 15, 46, and 47% and 43, 69, and 126% greater than that of Hutcheson, respectively. Seed soybean initiated flowering 15 d earlier than forage soybeans, resulting in lower leaf and stem yield. Forage quality of whole plants (N concentration and dry matter digestibility) of whole plant was similar across cultivars. Seed yield of Tyrone was lowest (690 kg ha−1), as compared to Donegal (1180 kg ha−1), Hutcheson (985 kg ha−1), or Derry (939 kg ha−1). Nitrogen concentration and digestible dry matter (DDM) of seed for all cultivars were similar. We concluded that forage soybean cultivars could provide greater leaf and stem biomass for livestock in the southern Great Plains during late summer and early fall when perennial warm‐season grasses are less productive.