Níveis ótimos de NPK na adubação de arroz irrigado em solos de várzea da Zona da Mata, Minas Gerais

Resumo

Ten field trials were conducted to study the optimum levels of nitrogen, phosphorus and potassium fertilizers for irrigated rice grown on low-land soils of the "Zona da Mata" region of the State of Minas Gerais, Brazil.

The experimental design used in this experiment was a 3x3x3factorial. The fertilizers used were ammonium sulfate, ordinary superphosphate and potassium chloride applied at the rates of 0, 60 and 120 kg/ha of N, P205 and K20.

Young rice plants were transplanted with a spacing of 40 cm between rows and 20 cm within rows.

The data of 10 trials were grouped and analysed together.

The optimum levels of N and P05 which resulted in the best economical production, within a reasonable price range of the fertilizers and rice, were determined. 

Under the conditions of this experiment, the following conclusions can be drawn:

1 - All three elements tested gave significant results, but the greatest response was obtained with the application of phosphorus.

2 - Nitrogen fertilization gave a small response with the optimum economic level varying from O to 45 kg/ha ofN depending on the market price of the nitrogen and rice.

3- Asa resultofthe greater response to the phosphate fertilizer, the optimum economic level of 80 kg/ha of P205 was only slightly dependent on the market price of the fertilizer and rice.

4 - The responseto potassium was linear for the three levels used. Based on the results obtained in this experiment and those reported in the literature, the optimun level of potassium was 40 kg/ha of K20.