Ammonia Volatilization and Marandu Grass Production in Response to Enhanced-Efficiency Nitrogen Fertilizers

Abstract

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. The experiment was took place in a pasture area, two growing seasons. A randomized block design with four replications was used, in a 4 × 2 + 1 factorial arrangement, consisting of four N sources (Urea—UrConv; Ammonium nitrate—AN; Urea + NBPT—UrNBPT; Urea + Duromide—UrDuromide) and two nitrogen rates (100 and 200 kg ha−1 year), plus a treatment without nitrogen fertilization (control). At both N rates, ammonia volatilization from UrConv100/200 was greatest. Ammonia volatilization was less after UrNBPT and UrDuromide application, with values similar to AN. Ammonia losses from UrDuromide tend to be lower than from UrNBPT. 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 UrDuromide and UrNBPT was greater than that of UrConv. 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. The UrDuromide reduce N losses by volatilization compared to UrNBPT and Urconv, and resulted in greater total DM production and relative leaf production of Marandu, in comparison to UrNBPT, AN and Urconv.