The present work was carried out to determine concentration and accumulation of micronutirents from 30 days after cutting the grass up to 180 days old. For the purpose an area comprising 600 m² of Latos solo Vermelho Amarelo (oxisol) at São Carlos, State of São Paulo, Brazil on the farm Canchim, research institute wich belongs to EMBRAPA, the trial was conducted. The neadw was cut and fertlized with ammonium sulphate at the rate of 250 kg/ha. At intervals of 30 days after the cutting up to 180 days plants corresponding to one square metre were collected. The authers concluded: The concentration of Cu is highest at the 30 days (7.63 ppm); The concentration of Zn is highest at the 180 days (22.66 ppm) and lowest at the 120 days (12.42 ppm); The concentration of B is highest at the 150 days (11.76 ppm) and lowest at the 60 days (1.69 ppm); The concentration of Mn is highest at the 180 days (133-8 ppm) and lowest at the 30 days (49.6 ppm); The concentration of Fe is highest at the 180 days (236.25 ppm) and lowest at the 30 days (49.6 ppm); The accumulation of Cu is highest at the 90 days. The accumulation of Zn and Fe did not differ with the age of the grass. The accumulation of B and Mn is highest at the 180 days. The greatest amounts of micronutrients content in 1.425 kg/ha of dry matter obey the following order: Fe - 286 g; Mn - 157 g; Zn - 23 g; B - 13-2 g; Cu - 7.6 g.