Concentration of macronutrients in soybean (Glycine max (L.) Merrill) as a function of age, application of phosphorus and of the parts of the plant

Abstract

This study was conducted with the objective of determining the concentration of macronutrients in the plant as function of fertilization with nitrogen, phosphorus and potassium. A 3³ factorial experiment with three replications was performed. The experimental area was located at Piracicaba (ESALQ), the soil belonging to the Guamium series. IAC-2, an indeterminate soybean cultivar, was used. N, P and K were applied in the rows at the levels of 0, 20 and 40 kg/ha (N), 0, 60 and 120 kg/ha (P(2)0(5)), and 0, 30 and 60 kg/ha (K(2)0), Plant samples were taken at 21-day intervals at emergence and continuing until partial fall of the leaves (105 days after emergence). The several plant parts were analysed for macronutrients (.N, P, K, Ca, Mg and S). The following conclusions were reached: during the period of greatest efficiency of the crop, the level of 40 kg/ha of nitrogen increased the nitrogen concentration in the upper leaves. The level of 120 kg/ha of P2O5 increased the concentration of phosphorus and potassium in the upper leaves. The highest concentration of calcium and magnesium were found in the lower leaves, while the highest concentrations of sulphur were found in the upper leaves, independent of the levels of N, P and K applied to the soil.