Comparison of Warm Season Legume Production Under Drip Irrigation in the Summer in a Semiarid Region of West Texas.

Legumes have many benefits including soil enrichment, green manure, feed for economically important wildlife species, and healthy forage for livestock.  In this experiment, three legume species: lablab (Lablab purpureus), cowpea (Vigna unguiculata) and mungbean (Vigna radiata) were planted in a clay soil with drip irrigation in a randomized complete block design.  A total of four blocks were planted, each containing one replication of three rows of each legume.  The rows were at a 90 cm spacing.  Lablab was planted at 15 cm intervals within the row and cowpea and mungbean were planted at 7.5 cm intervals.  The experiment was designed to determine if drip irrigation would be a suitable method for growing legumes for forage in semiarid conditions.  The three legumes that were compared were selected due to their suitability as forage species for goats.  Around the time of flowering, plants were destructively harvested to examine morphological characteristics.  We found that plant leaf area was significantly higher (P = 0.0121) in lablab (3,760 cm²) than both cowpea (688 cm²) and mungbean (787 cm²).  Plant aboveground dry weight was significantly (P = 0.0357) higher for lablab (36.1 g) than cowpea (7.40 g) while mungbean (14.0 g) did not significantly differ from either. The average number of plants per hectare was significantly greater (P = 0.0002) for cowpea (325,000) and mungbean (310,000) than lablab (49,200).  The total dry mass per hectare for the site was not significantly different (P = 0.5340) for any of the species.  However, the dry mass per hectare of each legume was in the typical range seen in literature, so drip irrigation would be a viable method to grow any of these legumes as a forage supplement.