DRIS para avaliação do estado nutricional da soja em duas regiões do cerrado brasileiro / DRIS to evaluate the nutritional status of soybean in two savanna areas in Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Nowadays, soybean is the main oleaginous plant in Brazil, cultivated in all latitudes of the country it is the most important agricultural product of exportation. The high cost of fertilization and the importance of the mineral nutrition over productivity, make indispensable the use of evaluation techniques for the nutritional status as well as the foliar diagnosis. The Diagnosis and Recommendation Integrated System (DRIS) uses the concept of nutrient balance, it seems to be less subject to the interference of local particularities of the environment and of the systems of plant sampling. The aim of the present work was to test different methods of DRIS calculation functions, to establish a DRIS reference norm, and to evaluate the nutritional status of soybean in the areas comprehended by the south of Maranhão and southwest of Piauí and Mato Grosso. The study used 1555 results of foliar chemical analysis and productivity of production fields in the southern areas of Maranhão and the southwestern areas of Piauí and 5734 results of foliar chemical analysis and productivity of the research fields and production of Mato Grosso. The sampling consisted in collecting the diagnostic leaf corresponding to the third or fourth leaf with petiole, starting from the apex of 50 plants per planting field in full blooming. The sub-population of high productivity, nutritionally balanced, was determined by the best correlation of Index of Nutritional Balance (INB) with the productivity of the sampling bank. The methodologies DRIS Beaufils (1973), Jones (1981), and Elwali &Gascho (1984) were tested in order to obtain the DRIS indices, for which relationships were chosen using the method of variance ratio. The DRIS indices were classified as deficient, normal, and excessive. They were compared with the criterion of the sufficiency ranges. The methodologies of calculation DRIS functions (Beaufils, 1973; Jones, 1981; Elwali &Gascho, 1984) presented similar results in nutritional diagnosis of soybean in the studied areas. The relation between the productivity and INB was better when DRIS norms were established using the reference population with productivity ≥3600 kg ha-1 for the southern areas of Maranhão and southwestern areas of Piauí and ≥4800 kg ha-1 for Mato Grosso. The method of calculation DRIS functions proposed by Jones (1981) was chosen to evaluate the nutritional status of soybean in the southern areas of Maranhão and southwestern areas of Piauí and Mato Grosso for its usefulness easiness. Copper was the most limiting nutrient for soybean productivity in the southern areas of Maranhão and southwestern areas of Piauí. Phosphorus was the most limiting nutrient for the productivity in Mato Grosso. The DRIS method using specific norms in the southern areas of Maranhão and southwestern areas of Piauí and to Mato Grosso, was efficient in the nutritional diagnosis of soybean.

ASSUNTO(S)

mato grosso dris - norm soja dris – norma piauí mato grosso maranhão cerrado maranhão savanna soybean piauí

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