Calibração de nitrogênio para o trigo, em solo do Distrito Federal

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Most agricultural soils in Brazil have low levels of available N. Therefore, it is necessary to apply N fertilizers to meet the plants demands. In order to calibrate N for wheat, a yield trial was carried out on a Red Latossol, during the 2004/2005 agricultural year, at the Embrapa Cerrados Research Station. A randomized block design was used, with six replications. The treatments were five doses of N (70-140-210-280-350 kg ha-1) and one control (no nitrogen fertilization). Soil samples were collected at layers of 0-20 cm and 20-40 cm and four different chemical extractors were used to estimate the nitrogen availability. The highest determination coefficients were obtained for the 0-20 cm samples, suggesting this is the layer for routine N analysis for wheat. The order of the extractors, according to the highest R2, at the 0-20 cm layer was: KCl 2M a 100C (R2 = 0.997**) >H2O2/MnO2 (R2 = 0.992**) >buffer pH11.2+ NO3- (R2 = 0.985**) >buffer pH11.2 (R2 = 0.960**). The amount of N in the plant was affected by nitrogen fertilization. The treatment where N was not applied showed the lowest amounts of N in grain, leaf, and stem+leaf. Wheat productivity was affected positively by N fertilization, with increasing production up to 140 kg N ha-1. The economic dose of N varied from 42 kg N ha-1 up to 114 kg N ha-1, considering three different price of N/price of the product ratio (n/w). The physiological-economic critical levels of N, obtained for a 5/1 n/w ratio, were: 87 mg kg-1 (H2O2/MnO2), 84 mg kg-1 (KCl 2M at 100C), 80 mg kg-1 (buffer pH11.2+NO3-), and 60 mg kg-1 (buffer pH11.2).

ASSUNTO(S)

nitrogen fertilization nitrogen availability disponibilidade de nitrogênio ciencias agrarias triticum aestivum. adubação nitrogenada triticum aestivum.

ACESSO AO ARTIGO

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