Momento de aplicacion de nitrogeno: efecto en eficiencia de uso del fertilizante, rendimiento y concentracion proteica en grano de cebada cervecera en Uruguay | Effect of timing of nitrogen application on fertilizer use efficiency, yield and grain protein concentration of malting barley in Uruguay
2002
Otegui, O. | Zamalvide, J. | Perdomo, C. | Goyenola, R. | Cervenanasky, A.
In Uruguay, malting barley (Hordeum vulgare L.) is produced mainly for the export market, which requires a grain protein concentration between 10.5 and 11.5%. Nitrogen (N) management affects not only yield but also grain protein concentration, and the variability of soil, weather and management conditions justifies site-specific N recommendations. N rates are adjusted using a plant test at Zadoks 30 (Z30) and soil tests at pre-planting and at Z22. However, there is a lack of information about the effects of these different moments of N application on N fertilizer use efficiency (FUE). This information is important, because a high FUE would result in economic gains for the farmers and less risk of contamination for the environment. With the objective of evaluating the overall effect of timing of N application on yield, grain protein concentration and N-FUE, three experiments were set up between 1997 and 1998 in the area of Colonia, Uruguay. The treatments consisted of different moments of N-fertilization (30 kg ha(-1)), applied at planting (only in 1997), Z22, Z30, or Z39. The FUE was evaluated using 15N. The result of this study shows that the best time for checking the N status of the crop and for N application seems to be a combination of planting and Z22. The diagnosis at Z30 would be recommended only when N can be applied in the vicinity of this physiological stage, because applications at a later stage can increase the risk of excessive grain protein concentration. However, N FUE tend to increase with the delay of N fertilization from planting to Z39.
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