Yield, Water Use Efficiency, and Nutritive Value of Six Warm-Season Perennial Grasses in Response to Irrigation Level

The decline of the Ogallala Aquifer coupled with the number of irrigated acres in the Texas Panhandle has raised concerns about the future of sustained irrigation in the region. This three-year study determined yield, water use efficiency (WUE), and nutritive value of six warm-season perennial grasses produced under dryland, limited, and full irrigation conditions. The six grass species in the study were Texoka buffalograss, Haskell sideoats grama, WW Spar old world bluestem, Blackwell switchgrass, Hatchita blue grama, and Wrangler bermudagrass. Dry matter (DM) yield ranged from a high of 8.4 ton/acre with old world bluestem under full irrigation to a low of 1.9 ton/acre with buffalograss under dryland production. Highest WUE was achieved with old world bluestem averaging 790 lb/acre-inch, regardless of irrigation level. The largest increases in WUE were observed in buffalograss and bermudagrass from dryland to limited irrigation, increasing 67 and 33%, respectively. Crude protein (CP) content was high throughout the study, regardless of irrigation level or grass species. Switchgrass was the most digestible (76.9% in vitro true digestibility, IVTD) followed by old world bluestem, while bermudagrass and sideoats grama were the least digestible. In this study, old world bluestem proved to be the best overall grass when considering DM yield, WUE, and forage quality.