Ammonia volatilization and marandu grass production in response to enhanced-efficiency nitrogen fertilizers

Abstract

Aims The objective of this study was to evaluate dry matter (DM) production of Urochloa brizantha cv. Marandu and ammonia volatilization in response to rates and sources of enhanced-efficiency N fertilizers. Methods The experiment was installed in a pasture area, evaluated over two growing seasons. A randomized block design with four replications was used, in a 4x2+1 factorial arrangement, consisting of four N sources (Urea - Ur Conv ; Ammonium nitrate - AN; Ureia+NBPT - Ur NBPT ; Urea+Duromide - Ur Duromide ) and two nitrogen rates (100 and 200 kg ha -1 year), plus a treatment without nitrogen fertilization (control). Results At both N rates, ammonia volatilization from Ur Conv100/200 was highest. Ammonia volatilization was lower after Ur NBPT and Ur Duromide application, with values similar to AN. Ammonia losses from Ur Duromide tend to be lower than from Ur NBPT . The N use efficiency in dry matter production of Marandu was influenced by the N sources and rates. At both N rates, the efficiency of Ur Duromide and Ur NBPT was greater than that of Ur Conv . With regard to total DM and leaf percentage in response to N rates, DM production increased after 200 kg N ha -1 rates in response to all sources, in both years. Conclusions The Ur Duromide reduce N losses by volatilization compared to Ur NBPT and Ur conv, and resulted in greater total DM production and relative leaf production of Marandu, in comparison to Ur NBPT, AN and Ur conv.