Rates of urea with or without urease inhibitor for topdressing wheat

The urease inhibitor NBPT(N-(n-butyl) thiophosphoric triamide) is a management alternative to increase urea efficiency in topdressing because it reduces NH3 volatilization. The objective of this study was to evaluate N recovery and yield performance of wheat ( Triticum aestivum L.) ‘BRS 254’ fertilized with different urea or urea + NBPT rates in topdressing. The experiment was conducted from May to September 2007 in Viçosa, Minas Gerais, Brazil. Treatments followed a 5 × 2 + 1 factorial design consisting of five N fertilizer rates (30, 60, 90, 120, and 150 kg ha-1) as urea or urea + NBPT (Agrotain® ) applied as topdressing and a control without N. The experiment was a randomized complete block design with four replicates. Adding NBPT to urea resulted in better N utilization by wheat plants. The 100 kg N ha-1 topdressing rate provided the best apparent N recovery by wheat plants, whereas 90 kg ha-1 provided the best N use efficiency

Yield and nitrogen recovery of wheat plants subjected to urea application with or without a urease inhibitor in the absence of irrigation

The use of urease inhibitors and irrigation are management options to increasing the efficiency of top-dressed urea by reducing NH3 volatilization. The purpose of this study was to evaluate the productive performance and N recovery of 'BRS 254' wheat plants without irrigation after applying urea or urea+NBPT [N-(n-butyl)thiophosphoric triamide] as the top dressing. The experiment was carried out in Viçosa, MG, Brazil, between May and September of 2008 using a complete randomized block design with a 2×6+1 factorial arrangement of the following treatments: 1) urea or urea+NBPT, 2) six periods without irrigation (0, 48, 96, 144, 192 or 240 h after applying the top-dressing fertilizer), and 3) a control without N; there were four replications. The data were subjected to an analysis of variance (P≤0.05). The mean values of the treatments with urea or urea+NBPT were compared by Tukey's test (P≤0.05), and the effects of the periods without irrigation were analyzed by a regression (P≤0.05). The results of the study show that NBPT did not lead to agronomic advantages for the wheat crop under the study conditions, and the absence of irrigation after urea application as the top dressing led to less N utilization by the wheat plants.El uso de inhibidores de ureasa o de riego son opciones de manejo para aumentar la eficiencia de la urea aplicada en cobertera, a través de la reducción de la volatilización de NH3. La investigación tuvo como objetivo la evaluación del desempeño productivo y la recuperación de N por plantas de trigo 'BRS 254' sin riego, después de la aplicación de urea o urea+ NBPT [N-(n-butyl)thiophosphoric triamide] en cobertera. El experimento se llevó a cabo en la ciudad de Viçosa, MG, en Brasil desde mayo hasta septiembre de 2008. Los tratamientos siguieron un arreglo factorial 2×6+1, en el cual la urea o urea + NBPT se combinaron en seis periodos sin riego: 0, 48,96, 144, 192 y 240 horas después de la aplicación del fertilizante en cobertera, además de una muestra de control sin la aplicación de N. Para el diseño experimental, se utilizaron los bloques completos al azar con cuatro repeticiones. Se concluyó que el NBPT no proporciona ventajas agrícolas a la cosecha de trigo, bajo las condiciones estudiadas. La ausencia de riego después de la aplicación de urea en cobertera provee un aprovechamiento menor de N por las plantas de trigo