Warm-Season Annual Legumes for Forage Production in Southern High Plains.

Warm-season annual legumes can be an option for forage production in the Southern High Plains, USA. The objective of this study was to assess DM yield and nutritive value of four warm-season annual legumes in southeastern New Mexico. Two lablab [Lablab purpureus (L.) Sweet] beans cv ‘Rio Verde’ and ‘Rongai’, and two cowpea (Vigna unguiculata L. Walp.) beans cv ‘Iron and Clay’ and ‘Catjang’ were sown on June 1, 2009, at New Mexico State University’s Agricultural Science Center at Artesia in a randomized complete block design with four replicates. The seeding rate was 43 kg ha^-1 and plots were 7.2 m². The study was irrigated five times during the growing season and fertilized based on soil analysis. Legumes were harvested twice (73 and 97 DAP) for DM yield at a maturity stage that ranged from vegetative to 10% bloom. Forage nutritive value was analyzed using an NIRS system. Lablab cultivars had greater DM yield than cowpea cultivars with an accumulated yield for both cuts of 6.6 and 8.9 Mg ha^-1 for Rio Verde and Rongai, respectively, and 4.2 and 1.0 Mg ha^-1 for Iron and Clay and Catjang, respectively (P < 0.01). At first cut, crude protein concentration was greater (P < 0.01), NDF concentration was lower (P < 0.05), and ADF concentration was not different (P > 0.05) among cowpea and lablab cultivars. Averaging across cultivars within species, CP and NDF concentrations were 253 and 263 g kg^-1 for cowpea and 228 and 288 g kg^-1 for lablab, respectively.  We conclude that the lablab is a potentially better option than cowpea for forage production in Southern High Plains.