Evaluation of Slow‐Release Nitrogen Sources on Baron Kentucky Bluegrass

Abstract

As new nitrogen (N) sources are introduced, it is important that they be evaluated and their release characteristics determined in order to provide us with a basis on which to make fertilizer recommendations. In this study, several N sources were evaluated for maintenance fertilization of Kentucky bluegrass (Poa pratensis L.) turf. Treatments included isobutylidene diurea (IBDU) materials of two particle‐size ranges, sulfur‐coated ureas (SCU) in two size ranges from Canadian Industries Limited (CIL), SCU from the Tennessee Valley Authority (TVA), ureaformaldehyde (UF), activated sewage sludges, Organiform, soluble N sources, and combinations of slow‐release and soluble N. All N sources were applied at a rate of 197 kg N·ha−1·yr−1, divided into equal fall and spring applications for 3 consecutive years. Weekly clipping yields, color ratings, and annual N recovery were the response criteria.Sulfur‐coated urea produced a more uniform growth and had higher N recovery than IBDU, which was characterized by a delayed response following fertilization. Turfgrass response to the CIL and TVA SCU materials applied alone was similar. Particle‐size effects with CIL SCU were slight; however, N release was quicker from fine IBDU than coarse IBDU. Slow‐release characteristics were also observed for ureaform, Organiform, and the sludges, but turf quality was generally poor for these treatments. Substituting soluble N for a portion of the SCU N gave inferior turfgrass response as compared to SCU applied alone. When soluble N was used in conjunction with ureaform, Organiform LT, and IBDU, turfgrass response was improved over that obtained when these N sources were used alone. Recovery of N in the clippings was greatest for soluble N sources and SCU treatments (48 to 52%), while lowest values (15 to 29%) were associated with ureaform, Organiform, and sludges.

Single Fall Applications of Coated Urea Fertilizers Produce a High Quality Kentucky Bluegrass Turf

“…This frequent fertilization increases the time, effort, and dedication required to maintain a high quality lawn. Thus, controlled-release N sources, like SCU that do not rely on microbial degradation for N release, have been evaluated for their ability to produce a high quality turf (4,14,15,18,30). The newest group of controlled-release N sources is PCU but response data is limited and direct comparisons to SCU or urea in the same study is generally lacking.…”

Aboveground Responses of Cool-Season Lawn Species to Nitrogen Rates and Application Timings

“…It is generally believed that KBG requires more N to sustain quality than PRG or TTTF (Christians, 2004). Since KBG is the most widely planted lawn species, the majority of research has been conducted using this species (Hanson and Juska, 1961;Hummel and Waddington, 1981;Starr and DeRoo, 1981;Jiang and Hull, 1998;Heckman et al, 2000) or KBG species mixtures (Kopp and Guillard, 2002). Much less information exists for PRG (Watson, 1987;Liu et al, 1993;Miltner et al, 2001;Engelsjord et al, 2004), or TTTF (Liu et al, 1993;Hall et al, 2003;Bigelow et al, 2005;Liu and Hull, 2006), which comprises a large portion of the lawns planted in the last decade.…”

Effects of slow-release fertilizers on growth and on uptake and leaching of nutrients in Kentucky bluegrass turfs established on sand-based root zones

“…Some slow-release fertilizers may possess this characteristics and in several studies have been found to reduce or eliminate leaching losses of nutrients (Bredakis and Steckel 1963;Rieke and Ellis 1974;Brown et al 1982;Snyder et al 1984;Mancino 1991). In addition, lower risk of N loss by volatilization, less chances of fertilizer burn, fewer applications at higher rates and consequent economic saving, and a longer duration of N release, are among the several reported benefits of the slowrelease fertilizers (Hummel and Waddington 1981).…”