Abstract

LANDRISCINI, María Rosa; GALANTINI, Juan Alberto  and  MARTINEZ, Juan Manuel. Eficiencia de recuperación de nitrógeno por los métodos de la diferencia y de la dilución isotópica. Cienc. suelo [online]. 2016, vol.34, n.1, pp.155-162. ISSN 1850-2067.

The nitrogen (N) use efficiency can be determined by the isotopic dilution or by the difference method. The objectives were to measure the destination of foliar fertilizer and to compare the Nitrogen Recovery Efficiencies (NRE) between the mentioned methods. A field experiment was conducted in the southwest of the Buenos Aires Province (Las Oscuras). Nitrogen rates of 0, and 50 kg N ha^-1 were applied at sowing and 0 and 25 kg N ha^-1 at anthesis. The enriched urea was applied in anthesis and post-anthesis in the microplots. Yields were low with no response to the initial or foliar fertilization: 2100 and 2154 kg ha^-1 for 0 and 50N without foliar N and 2160 and 2303 kg ha^-1 with foliar N application. In the isotopic plots, wheat accumulated 83 kg in aboveground biomass and 52 kg N ha^{-1 in grain without a significant impact of initial or foliar fertilization. Nitrogen from the foliar fertilizer was accumulated 20% in aerial dry matter (ADM) and 12% in the grain, with a recovery of 6 kg N ha-1}. Accumulated N in straw ranged 10 kg N ha^-1 and unrecovered N varied from 7,2 to 8,3 kg N ha^-1 (30%). The NRE varied from 30% to 54 according to the difference method for the initial 0 and 50N treatments in ADM and grain, with an accumulation of 2,4 to 6 kg N ha^-1. Isotopic determined NRE was of 70% in ADM and 25 % in grain. Again, grain accumulation was of 6 kg N ha^-1. The differences between the methods suggested the need to identify the factors that influence these estimates.

Keywords : Wheat; ¹⁵N; Nitrogen recovery; Foliar urea.

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