Method for Flux‐Chamber Measurement of Ammonia Volatilization From Putting Greens Foliarly‐Fertilized by Urea

Abstract

Foliar fertilization is an increasingly popular method of ensuring golf course putting green nitrogen (N) sufficiency in season. The low cost, high N‐content, and favorable handling characteristics of urea (46‐0‐0) make it a common N‐source in foliar treatments of horticultural crops. While numerous investigations confirm incomplete recovery of foliarly‐applied urea‐N by turfgrass, few field assessments of NH3 volatilization from greens have been conducted. Meanwhile, NH3 emissions reduce air quality and contribute to non‐point nutrient loading of water resources. The research objectives were to (i) develop a method for field‐implementation of closed dynamic/flux chambers to measure NH3 volatilization from 0 to 24 h following foliar application of urea‐N to putting greens; and (ii) infer the significance of flux chamber NH3‐N volatilization measures relative to levels arising from simultaneous static‐chamber measures. Creeping bentgrass (Agrostis stolonifera L. “Penn G‐2”) putting greens were foliarly treated by 20–44 kg urea‐N ha−1 from 2013 to 2015, and NH3 volatilization measured using H3BO3 trap‐equipped flux and/or static chamber systems. Flux chamber measures of NH3 volatilization accounted for 7.1% of the urea‐N fertilizer applied 24 h previous. Simultaneous static chamber measures of NH3 volatilization were an order of magnitude less. A replicated flux chamber trapping efficiency trial showed 63% mean NH3 recovery. Thus under the duration and conditions described, 7.1–11.2% of foliar urea‐N applications can be expected to volatilize from putting greens. Regarding closed chamber system measurement of NH3 volatilization from small field plots, the described flux chambers afford applied scientists a more precise and efficient method than static chambers.