Ammonia volatilization following nitrogen fertilization with enhanced efficiency fertilizers and urea in loblolly pine (Pinus taeda L. plantations of the southern United States
Abstract Ammonia (NH 3 volatilization losses following surface application of urea and three enhanced efficiency nitrogen (N) containing fertilizers (EEFs) were compared in six thinned mid rotation loblolly pine Pinus taeda L. stands across the southern United States. All fertilizer treatments were labeled with 15 N ~370%0, 0.5 AP) and applied during two different seasons (spring, summer) in 2011 to open chamber microcosms. Individual microcosms were sampled 1, 15 and 30 days after fertilization to estimate remaining 15 N. Losses of fertilizer N were determined using a mass balance calculation. Significantly less N loss occurred following fertilization with EEFs compared to urea after all sampling days for both seasons. Because root uptake was eliminated in the microcosms and there was no leaching of 15 N below the microcosms, the most likely loss pathway of the 15 N from the microcosms was NH 3 volatilization. There were generally no differences among the individual EEFs. Following spring application, the mean NH 3 volatilization during the 30 day experiment ranged from 4% to 26% for the EEFs compared to 26 40% for urea. In summer, mean NH 3 volatilization for EEFs ranged from 8% to 23% compared to 29 49% for urea. This research highlights the potential of EEFs to reduce loss of fertilizer N in forest systems, potentially increasing fertilizer N use efficiency in these pine plantations.