Nathaniel Leiby
Published: 2021
Total Pages:
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Supplying sufficient plant available nitrogen (N) to creeping bentgrass putting greens and fairways is one of the most vital maintenance tasks of astute golf course superintendents. Possibly the most popular and time-tested approach used by these superintendents is to foliarly apply urea-N fertilizer on a biweekly basis. However, previous research evaluating this practice has demonstrated the occurrence of a detrimental phenomenon known as ammonia volatilization. While the foliar application of urea-based fertilizers to creeping bentgrass putting greens and fairways is a relatively ubiquitous strategy employed by golf course superintendents, the application of petroleum-derived spray oils (PDSO) to creeping bentgrass systems is a comparably novel strategy. A two-year study was conducted to quantify the fate of foliar applications of urea-based fertilizers in combination with PDSO (Civitas Turf DefenseTM) to Penn G-series creeping bentgrass (Agrostis stolonifera L.) putting greens and Declaration creeping bentgrass fairways. Foliar applications of conventional urea, urea ammonium nitrate (UAN), methylol urea, and stabilized urea (UMAXXTM, Koch Agronomic Services, LLC) were made on 14-day intervals to supply 14.64 kg N ha-1 per growing month to the putting green and 19.52 kg N ha-1 per growing month to the fairway. Foliar applications of urea-based fertilizers were made alone and in combination with PDSO. Inclusion of PDSO with N-fertilizer sources significantly influenced vigor, leaf N content, fertilizer-N recovery, fertilizer-N loss as ammonia, and canopy color. Monthly putting green and fairway clipping yields indicated an average yield increase of 16.5 kg ha-1 when comparing combination treatments to their fertilizer-only counterparts. Additionally, both the putting green and fairway studies demonstrated an average increased fertilizer-N recovery of 0.865 kg ha-1 when N-fertilizers were applied in combination with PDSO. Finally, urea complimented with dicyandiamide and N-butyl thiophosphoric triamide reduced putting green fertilizer-N volatilization from 4.6% to 1.7% compared to conventional urea. However, this significant difference was not observed when both N-fertilizer sources were applied in combination with PDSO.