Abstract
Tall fescue (Schedonorus arundinaceus [Schreb.] Dumort.) is a perennial forage grass with good nutritive value and has the potential to be grown in many parts of the world. Field experiments were conducted over a 3-year period (2010-2012) at two locations [University of Wyoming Powell Research and Extension Center (PREC) and a producer field (Stroh farm) in Powell, Wyoming] to evaluate forage accumulation, forage nutritive value, agronomic efficiency (AE) and relative profitability (RP) of using different cultivars or lines and nitrogen (N) rates in tall fescue production systems. The study design was factorially arranged in a randomized complete block with four replications at PREC and three replications at Stroh farm. Treatments comprised seven tall fescue cultivars ('97TF584,' 'Cowgirl,' 'Fawn,' 'Kentucky-31,' 'Maximize,' 'Soft,' and 'Texoma') and three N rates (0, 56 and 112 kg/ha). There was a linear response (p = .02) of annual forage accumulation to year x N. Crude protein, in vitro dry matter (DM) digestibility, acid detergent fiber and neutral detergent fiber ranged from 90 to 102, 704-719, 360-383 and 555-581 g/kg, respectively. There were main effects (p < .01) of year, cultivar and N rate on AE and RP. Kentucky-31 had the highest AE (53 kg DM/kg N), and AE was greater in the 56 kg N/ha (48 kg DM/kg N) compared to the 112 kg N/ha (39 kg DM/kg N). However, RP (where RP greater than 1 means revenue from N application is greater than the 0 kg N/ha treatment) was greater in the 112 kg N/ha (2.44) compared to the 56 kg N/ha (1.93). Among the cultivars, Kentucky-31 had the highest RP of 2.56. Overall, all cultivars were responsive to added N and showed potential to be profitable under grass hay production systems.