###### Abstract  
Low cost and favorable handling characteristics make urea (46-0-0) a leading nitrogen source for frequent, foliar N fertilization of golf course putting greens in season. Yet few field investigations of resulting NH\({}_{3}\) volatilization from putting greens have been directed. Meanwhile, NH\({}_{3}\) emissions degrade air and surface water quality. Our objective was to quantify NH\({}_{3}\) volatilization following practical, low-N rate, and foliar application of commercial urea-N fertilizers. Over the 2019 and 2020 growing seasons in University Park, PA, USA, an industrial vacuum pump, H\({}_{3}\)BO\({}_{3}\) scrubbing flasks, and sixteen dynamic flux chambers were employed in four unique experiments to measure NH\({}_{3}\) volatilization from creeping bentgrass putting greens (_Agrostis stolonifera_ L. 'Penn G2') in the 24 h period ensuing foliar application of urea based-N at a 7.32 or 9.76 kg/ha rate. Simultaneous and replicated flux chamber trapping efficiency trials showing 35% mean NH\({}_{3}\) recovery were used to adjust NH\({}_{3}\) volatilization rates from treated plots. Under the duration and conditions described, 3.1 to 8.0% of conventional urea N volatilized from the putting greens as NH\({}_{3}\). Conversely, 0.7 to 1.1% of methylol urea liquid fertilizer (60% short-chain methylene urea) or 0.7 to 2.2% of urea complimented with dicyandiande (DCD) and \(N\)-(\(n\)-butyl) thiophosphoric triamide (NBPT) volatilized as NH\({}_{3}\). biological inhibitor; creeping bentgrass; dicyandiande (DCD); flux chamber; methylene urea; \(N\)-(\(n\)-butyl) thiophosphoric triamide (NBPT); nitrogen; nutrient fate; putting green; urea +
Footnote †: journal: Applied Sciences  
Fortunately, numerous urea + urease inhibitor combination products are marketed to professionals seeking to prevent gaseous loss. Under aerobic conditions, \(N\)-(\(n\)-butyl) thiolphosphoric triamide (NBPT, C4H14N3 PS) transforms into \(N\)-(\(n\)-butyl) phosphorotriamide and impedes urease activity by making a trifurcate bond to its active site [15; 16]. There currently exists a slew of evidence relating NBPT amendment of urea to near 50% relative reductions in ammonia emission following application to agricultural and horticultural production systems [17; 18; 19; 20]. Field experiments evaluating turfgrass recovery, or loss, of NBPT-complimented urea-N applications are limited and report mixed results. Results of a multiyear Kentucky bluegrass (_Poa pratensis_ L) field study that complimented 49 or 98 kg/ha urea-N drench applications (1630 L ha\({}^{-1}\)) with NBPT (1.1 kg/ha) did not show the NBPT amendment to be beneficial to turfgrass [21]. However, over four 96-h measurement periods following a 49-kg urea-N application to Kentucky bluegrass, treatments complimented with 0, 0.245, 0.49, or 0.98 kg NBPT ha\({}^{-1}\) (0, 0.5, 1, or 2% by mass) showed 18% of the conventional urea-N volatilized as NH\({}_{3}\)-N compared to 7% of the urea-N fertilizer complemented with up to 2% NBPT [22]. A multiyear putting green study employing a 20 kg urea-N ha\({}^{-1}\) rate reported 11% of conventional urea volatilized over a single day following foliar application, whereas only 3 to 5% of urea-N volatilized when complimented by dicyandaimide (DCD) and NBPT [23]. Most atmospheric ammonia in North America originates from livestock production and fertilizer application. In the presence of sulfate or nitrate, NH\({}_{3}\) constitutes the most significant and influential precursor to smog formation, i.e., particulate matter < 2.5 um in diameter (PM\({}_{2.5}\)). Elevated ammonia and PM\({}_{2.5}\) levels are monitored in numerous non-attainment regions in the US (Figure 1[24]) and abroad and are statistically correlated to adverse health effects [25]. Furthermore, ammonium deposition to surfaces, the primary atmospheric removal mechanism, is considered a serious threat to terrestrial and aquatic ecosystem health [26]. Modern golf course superintendents rely on practical field research results to maximize their fertilizer use efficiency.