Levels of sulfur effects on alfalfa production and mineral composition

Abstract

The sulfur (S) effect on alfalfa production and mineral composition was studied in plastic pots of five liters of soil Oxisol (Dark-Red Latosol dystrophic). The experimental design was completely randomized factorial scheme (4 x 6) with five replications. Four levels of sulfur (0, 25, 50 and 100 mg dm^-3 of CaSO₄.2H₂O ) and one level of K₂SO₄ (50 mg dm^-3 of S) in six cutting times, were studied. The analyzed variables were: dry matter production (DM) and amounts of crude protein (CP), P, K, Ca, Mg and S in the dry matter. The dry matter production and the P and S levels varied according to the sulfur dosage and the cutting time. The highest DM levels were observed with the 100 mg dm^-3 of S treatment, and the lowest with the one that did not receive S. The last two samples showed the lowest production, probably due to the nutrient extraction. The levels of S raised with sulfur application and diminished in the last cuttings. The opposite was observed with the level of P indicating a diluting effect or a negative interaction between P and S. The levels of CP, K, Ca and Mg varied according to the cutting number.