Canola, Indian mustard, Linola and wheat were grown in field experiments for two seasons in the contrasting environments of Junee and Condobolin, NSW, to investigate the effects of nitrogen (N) fertilizer on N uptake by the crops, the removal of N in harvested grain, N harvest indices, N use-efficiency, and soil N extraction. Junee is in the region where canola production is concentrated, and Condobolin is in the drier western margins for canola. Both sites had low baseline levels of soil mineral-N, and there were two times of sowing at Condobolin. Concentrations of N in shoots at anthesis were highest for canola and Indian mustard (1.7-3.5%), intermediate for Linola, and lowest for wheat (0.6-1.8%). Concentrations of N in stubble at maturity were lower than at anthesis (oilseeds 0.25-0.95%; wheat 0.16-0.49%). The order of grain N concentration was Indian mustard>canola=Linola>wheat. Concentrations of N in the crops were similar between seasons. Nitrogen fertilizer increased the accumulation of N by all crops at anthesis, but the magnitude of the increase depended on crop biomass which was related to the site and seasonal conditions. Nitrogen accumulation was greater for crops in the Junee region than at Condobolin. In most cases, the amounts of N accumulated in shoots of the crops at anthesis exceeded the amounts of fertilizer N applied. The oilseeds showed a net loss (-35%) and wheat a net gain (+24%) of N between anthesis and maturity. The amounts of N removed in grain ranged from 6 to 114kgha - 1 in 1991, and from 25 to 113kgha - 1 in 1992. Time of sowing at Condobolin had little effect on the amounts of N accumulated by shoots or grain. Nitrogen removals in grain usually exceeded the N applied at the lower rates, but not at the higher rates. Nitrogen harvest indices were either unaffected or decreased by N fertilizer. Mean N harvest indices were highest for wheat (0.79) and lowest for Linola (0.57). Indices of N use-efficiency generally decreased with increasing N fertilizer, and reflected seasonal conditions. The use-efficiency of N accumulated in the shoot ranged from 69kggrainkg - 1 N accumulated for wheat at Junee to as low as 6kggrainkg - 1 N for Linola at Condobolin. Canola, Indian mustard and wheat extracted soil mineral-N to the same extent and more effectively from the soil profile than Linola, due primarily to their greater rooting depth and N accumulation than Linola. Based on N uptake by shoots and N removal in grain, the suggested ranking for the quantity of N fertilizer applied to the crops in both regions when grown late in the cropping sequence is canola>Indianmustard~wheat>Linola.