Inibidor de urease (NBPT) e a eficiência da uréia na fertilização do trigo irrigado

• Autor(a) principal: Espindula, Marcelo Curitiba
• Data de Publicação: 2010
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1136
• topic: Triticum aestivum L.; Fertilizante nitrogenado; Volatilização de amônia; Desempenho agronômico; Triticum aestivum L.; Nitrogen fertilizer; Ammonia volatilization; Agronomic performance; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

NBPT (N-(n-butyl) thiophosphoric triamide), a urease inhibitor, has been reported as one of the most promising compounds to maximize urea nitrogen use in agricultural systems. The objective of this study was to evaluate urea use efficiency with the urease inhibitor NBPT [N-(n-butyl) thiophosphoric triamide)] (Agrotain®) in fertilization of irrigated wheat (Triticum aestivum L.). The study was conducted at Prof. Diogo Alves de Mello Experimental Farm, Federal University of Viçosa Viçosa-MG (20º45'S and 42º51' W and 650 m altitude) in the years 2006, 2007 and 2008. Four experiments were carried out in a randomized blocks design. In the first experiment, wheat plants cv. Pioneiro were subjected to two treatments (urea or urea + NBPT) using two modes of application: total dose at sowing (60 kg ha-1) or split (20 kg ha-1 at sowing + 40 kg ha-1 as topdressing at tillering), in a 2×2 factorial design with ten replications. Results showed that nitrogen splitting brought no benefit to the wheat crop under the cultivation conditions proposed, the use of urease inhibitor (NBPT) is beneficial to the wheat crop only when urea is topdressed. The second experiment was carried out using cv. BRS 254 in a 5×2+1 factorial design with four replications. The treatments consisted of five N doses (30, 60, 90, 120 and 150 kg ha-1) as urea or urea + NBPT and a control without nitrogen. Addition of NBPT to urea resulted in a better utilization of N by wheat plants; the nitrogen dose as topdressing that provided the best apparent recovery of N by wheat plants was 100 kg ha-1, whereas 90 kg ha-1 provided the best N use efficiency. The third experiment, using cultivar BRS 254, was arranged in a 2×6+1 factorial design with four replications. The treatments urea or urea + NBPT were combined with six periods of irrigation shortage (0, 48, 96, 144, 192 and 240 h) after fertilizer application as topdressing, plus a control without nitrogen. NBPT showed no agronomic advantages for wheat under the studied conditions. The lack of irrigation after topdressing with urea resulted in a lower utilization of N by wheat plants. The fourth experiment consisted of determining ammonia volatilization using the treatments of the third experiment. Evaluations were performed at 48, 96, 144, 192, 240 and 600 hours after topdressing. The use of urea + NBPT resulted in lower NH3 volatilization compared to urea-only treatments. The lack of irrigation increased NH3 volatilization from urea, but had no effect on NH3 volatilization from urea + NBPT.