Resumo

ORCELLET, JUAN MANUEL et al. EFICIENCIA DE USO DE NITRÓGENO EN CEBADA EN EL SUDESTE BONAERENSE: EFECTO DE APLICACIONES DIVIDIDAS. Cienc. suelo [online]. 2015, vol.33, n.1. ISSN 1850-2067.

Nitrogen (N) is the main nutrient limiting yield and industrial quality of barley (Hordeum vuggare L). Nitrogen split applications under humid environments should maximize N use efficiency (EUN). In southeastern Buenos Aires (SEB), the effect of split N rates on yield, EUN, protein percentage (PB) and N recovery efficiency in grain (ERNg) was evaluated. Two experiments (Lobería and Miramar) were conducted during 2012. Treatments consisted in four N rates applied at the two-leaves stage (Z12) (0, 40, 80 and 120 kg N ha^-1) and four rates split at different moments (80Nf, 120Nf, 180Nf₁ and 180Nf₂). Nitrogen rates and split applications affected yield and PB significantly. The N split application with the 80N rate increased yield 674 kg ha^{-1 in average (p <0,05), however the yield increase with 120N was not significant (280 kg ha-1}). Split applications (80 kg N ha^-1) increased EUN in 5,3 and 10 kg grain kg N^-1 with respect to a single application, for Lobería and Miramar, respectively. Furthermore, fractionation did not affect PB content. The ERNg was higher in the treatments with split rates compared to a single application. In Lobería, the ERNg increased 0,15 and 0,08 kg N kg N f^-1 for the 80 and 120 kg N ha^-1 rates, respectively, while in Miramar the ERNg was 0,11 kg N kg N f^-1 higher for both rates. For SEB, split N rates is a recommended management practice towards maximizing grain yield, EUN and for minimizing the N contamination impact on the environment.

Palavras-chave : Nutrition; Nitrogen; application time.

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