The experiment was conducted at the "Depressão Central do Rio Grande do Sul", from 04/21 to 06/02/94 (establishment of the pasture) until 11/06/94 (grazing period), with the objective to evaluate the dynamics, production, quality and the production cost of forage of the pasture of oat and ryegrass mixture, in continuous grazing, fertilized with different sources of nitrogen (urea or ammonium sulphate) applied as top dressing. The mixture was row-seeded (no-tilled) and fertilized with 200kg (05-30-15). Each source of nitrogen provided 200 kg/ha, divided in three applications. The source of nitrogen did not affect the daily dry matter (DM) accumulation rate (38.7 vs 36.1kg/ha/day of DM), the total forage production (7.410 vs 6.618kg of DM/ha) and forage quality. The percentage of DM was 18.26 vs 18.47%, crude protein content was 22.14 vs 22.69% and the in vitro organic matter digestibility was 57.85 vs 57.04% for urea and ammonium sulphate, respectively. The total cost of the pasture was of R$295.70 and R$379.40, of which nitrogen fertilizer represented 36.08 and 50.20%, for urea and ammonium sulfate, respectively. It can be concluded that for winter grass pastures, the choice of the source of nitrogen should be based on the cost/kg of N.
ammonium sulfate; cost; winter pasture; economics; grazing; urea
