| Summary: | 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<sub>3</sub> volatilization from putting greens have been directed. Meanwhile, NH<sub>3</sub> emissions degrade air and surface water quality. Our objective was to quantify NH<sub>3</sub> 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<sub>3</sub>BO<sub>3</sub> scrubbing flasks, and sixteen dynamic flux chambers were employed in four unique experiments to measure NH<sub>3</sub> volatilization from creeping bentgrass putting greens (<i>Agrostis stolonifera</i> 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<sub>3</sub> recovery were used to adjust NH<sub>3</sub> 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<sub>3</sub>. 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 dicyandiamide (DCD) and <i>N</i>-(<i>n</i>-butyl) thiophosphoric triamide (NBPT) volatilized as NH<sub>3</sub>.
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