Capabilities of four novel warm-season legumes in the southern great plains: Grain production and quality
Grain legumes could serve as a low cost nitrogen (N) and energy source for animal production in the southern Great Plains (SGP). This study evaluated the yield and nutritive value of grains of tropical annual legumes novel to the SGP. Included were cultivars of pigeon pea [Cajanus cajan (L.) Millsp.] (cv. GA-2), guar [Cyamopsis tetragonoloba (L.) Taub.] (cv. Kinman), cowpea [Vigna unguiculata (L). Walp.] (cv. Chinese red), mung bean [Vigna radiata (L.) Wilcz.] (cv. Berkins), and the grain soybean [Glycine max (L.) Merr.] (cv. Hutcheson) as a control. Seeds were inoculated and planted (60-cm row spacing) annually in mid-June 2004 through 2006. Seeding rates were varied to achieve 10 seeds m–1 row length. Grain was harvested at the end of growing seasons (90–120 d since planting), and grain samples were ground (1.0 mm) and analyzed for N concentration and in vitro digestible dry matter (IVDDM). Significant (P < 0.05) year x legume interactions were recorded for all characteristics, with variable legume responses among years. Guar produced both the highest (2730 kg ha–1 in 2004) and lowest (897 kg ha–1 in 2005) grain yields. Nitrogen concentrations were the highest in soybean grain (60.2–60.7 g kg–1) and consistently the lowest in pigeon pea (33.3–34.9 g kg–1). Soybean grain had the highest IVDDM (968–969 g kg–1), while pigeon pea had the consistently lowest digestibility (890–894 g kg–1). The four novel legumes produced grains that meet the nutritional requirements for all classes of stocker or feeder cattle.