Sulfur source and placement for newly established endophyte-free tall fescue

Previous research indicated that tall fescue (Festuca arundinacea Schreb.) may respond to sulfur (S) fertilization. However, data are limited concerni ng S management options to improve yield and quality of newly-established, endophyte-free tall fescue. Thus, a field study was conducted from 1989 to 1991 to determine the effects of S source (ammonium thiosulfate [ATS] and a mmonium sulfate [AS]); rate (17 and 34 kg S ha(-1)); and placement (broadca st, dribble [surface band], and knife [subsurface band]) on yield and quali ty of a newly-established, endophyte [Neotyphodium coenophialum (Morgan-Jon es and W. Gams) Glenn, Bacon, Price & Hanlin; syn. Acremonium coenophialum Morgan-Jones and W. Gams]-free, tall fescue. Compared to a no-fertilizer co ntrol, adding N alone more than tripled hay production to 6.09 Mg ha(-1), b ut the addition of fertilizer S had little effect on early-season productio n and only a 6% increase in later hay yields with ATS. Sulfur fertilization increased tissue S concentration and lowered N/S ratios. Increasing the S rate from 17 to 34 kg ha(-1) resulted in a small increase in S concentratio n and decrease in N/S ratio. Correlation analyses suggested that increasing S concentrations may reduce neutral-detergent fiber content and improve in vitro dry matter digestibility early in the season but not at hay harvest. Fescue sampled to simulate grazing in early spring yielded less but was hi gher in N/S ratios when S was knifed rather than surface applied. At hay ha rvest, knifing increased yield more than 10% and increased N concentration by 10 to 20% compared to surface application methods but had no effect on i n vitro dry matter digestibility.