This project was conducted to determine the efficiency of N usage by bell pepper grown with plastic mulch and trickle irrigation and to define a rate of applied N which is equal to uptake by the crop. It also assessed the usefulness of both petiole sap nitrate and total N in dried lead in determining N status and yield potential of bell pepper grown with plastic mulch and trickle irrigation in subtropical Australia. Lastly, it undertook a planting density study to investigate the effect of planting density on marketable yield of four commercial bell pepper cultivars grown over spring and autumn seasons.