Sulfur source and placement effects on forage yield and quality of established tall fescue

Previous research indicates that tall fescue (Festuca arundinacea Schreb,) may respond to S fertilization. However, data are limited concerning S management options to improve yield and quality of tall fescue. Thus, a field study was conducted from 1988 to 1990 to determine the effects of S source (ammonium thiosulfate [ATS] and ammonium sulfate [AS]), rate (17 and 34 kg S ha(-1)), and placement (broadcast, dribble [surface band], and knife [subsurface band]) on yield and quality of established, endophyte-infected tall fescue, Compared with a no-fertilizer control, adding N alone more than doubled hay production, to 7.15 Mg ha(-1), but the addition of fertilizer S had little effect on early-season production or later hay yields, Sulfur fertilization, especially in the ATS form, increased tissue S concentration, Lowered N/S ratios, and, to a lesser extent, increased tissue N concentration in the hay harvest, Few differences in measured parameters were related to S rate, Correlation analyses suggested that lowering N/S ratios may reduce neutral-detergent fiber content and improve in vitro dry matter digestibility. Fescue sampled to simulate grazing in early spring was lower in yield and tissue S concentrations, but higher in N/S ratios, when S was knifed rather than surface applied, At hay harvest, knifing fertilizers increased yield approximately 20% and increased N concentration by 10% compared with surface application methods, but produced lower in vitro dry matter digestibility.