Resumo

BARBIERI, PA; ECHEVERRIA, HE; SAINZ ROZAS, HR  e  MARINGOLO, M. Corn fertilization with slow-solubilization urea: ammonia volatilization losses and nitrogen use efficiency. Cienc. suelo [online]. 2010, vol.28, n.1, pp.57-66. ISSN 1850-2067.

Nitrogen (N) loss reduces the efficient use of this nutrient (EUN). When added to Urea, products such as the maleic-itaconic copolymer NSN and thiophosphoric N-(n-butil) triamide (nBTPT) slow down the rate of release of N and thereby diminish its loss. The aim of this study was to determine N volatilization losses (N-NH₃) during two growing seasons, grain yield, grain N content and NUE of corn under no-tillage using urea, urea with NSN and with nBTPT in combination with a dose of N (60 and 120 kg ha^-1). Volatilization losses were extended by 7 and 18 days in the first and second year, respectively. In both years, losses with Urea alone were higher than with Urea+NSN and with Urea+ nBTPT. In first year, N-NH₃ losses with Urea alone were 3% and 10% for 60 and 120 kg of N ha^-1, respectively, whereas with Urea+NSN and Urea+nBTPT the losses were less than 0.5% in both cases. In the second year, N-NH₃ losses with Urea alone were 2.3% and 3.8% for 60 and 120 kg of N ha^-1, respectively, and with Urea+NSN and Urea+nBTPT, less than 2%. Grain yield did not improve by increasing N or by adding NSN or nBTPT. Grain N content increased with higher doses of N and was not affected by the use of NSN or nBTPT. Nitrogen use efficiency, physiological efficiency and recovery efficiency were reduced with increasing N but were not affected by the use of NSN and nBTPT. The use of these products was therefore effective in reducing N-NH₃ losses but did not significantly affect grain yield, grain N content and NUE. This could be due to the fact that under the environmental conditions of the present study, N loss is not a factor of high relevance.

Palavras-chave : Volatilization; Corn; No-tillage; Urea; NSN; nBTPT.

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