Nitrogen fertilization in tall fescue: Productivity, agronomic efficiency and relative profitability

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 × 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