ALTERATIONS IN POTASSIUM, CALCIUM AND MAGNESIUM CONCENTRATIONS IN MARANDU PALISADEGRASS FERTILIZED WITH NITROGEN AND SULFUR RATES

An efficient pasture use in intensive production systems depends on the balanced mineral nutrition of the forage plant. Our objective was to evaluate changes in potassium, calcium and magnesium concentrations of Brachiaria brizantha, cv. Marandu grown on an Entisol with nitrogen and sulfur rates. The experiment was carried out in a greenhouse, in Piracicaba, State of Sao Paulo, from December 2004 to April 2005. A randomized block design was used in a fractionated 5 x 5 factorial design with 13 N and S rate combinations. The experimental units consisted of 3.6 dm(-3) plastic pots containing five Marandu plants. The grass plants were harvested three times and the shoot and its components separated in each ocasion. N fertilization influenced Ca and Mg concentrations as well as the proportions of K, Ca and Mg in the above-ground part of Marandu palisadegrass. The combined fertilization with N and S influenced K concentration negatively in the diagnostic leaves of the grass. Applications of N and S soil prior to Marandu establishment altered the nutritional balance in Ca, Mg and K of the plant.