Indirect Measurement of Ammonia Volatilization Following Foliar Application of Urea to Putting Green Turf.

Foliar nitrogen (N) fertilization continues to gain popularity with golf course superintendents, especially in regard to putting green nutrition.  However, little is currently known about the efficiency of this practice in the field, or the significance of the possible N loss mechanisms associated with foliar applications.  This project was conducted to document the extent of ammonia volatilization from turfgrasses managed as putting greens, following the applications of foliar N using urea (46-0-0), over a 24 h period.  Two different foliar fertilizer rates (0.5 g N m^-2 and 1.25 g N m^-2) were applied once monthly (May through September) to ‘Penn A-1’ creeping bentgrass and ‘Tifeagle’ ultradwarf bermudagrass established putting greens.  This study was initiated in 2007 and repeated in 2008.  Ammonia volatilization over a 24 h period was measured via boric acid trapping.  Month of year and N rate both had a significant effect on the amount of N volatilized from the turfgrass canopy.  The results from our field trial suggest that foliar urea-N applications to putting green turf can be made to actively growing plant tissue throughout the season without concern for substantial N loss via this pathway.