Annual ryegrass (Lolium multiflorumLAM. cv. Midmar) pastures were established on three sites, representing the Avalon, Katspruit and Inanda soil forms, with cut-plot experimentation over a period of four years (1987 - 1990). Nitrogen fertilizer was top-dressed at 0, 200, 300 or 400 kg N ha−1y−1and at intervals of 4 or 6 weeks. The dry matter (DM) yield data indicates that there was little justification for applying more than 40 kg N ha−1per application in autumn, and more than 50 kg N ha−1per application during spring. In addition, pastures top- dressed 4-weekly, at the above rates, produced yields equal or superior to equivalent annual rates applied on a 6-weekly application interval. With the increase in environmental concern about nitrates leaching into ground waters, and the potential for excessive applied N to accumulate to potentially toxic levels in pastures, the adoption of large infrequent applications of N is questioned.