Sulfur Source and Placement Effects on Forage Yield and Quality of Established Tall Fescue

Abstract

AbstractPrevious 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.