Soil nitrogen status is an important mediator of crop-weed competition, although the mechanisms for this are somewhat poorly understood and apparently contradictory experimental outcomes are reported in the literature. This controlled environment study characterizes the influence of soil N availability (0.2, 0.5, 2, 5 mM L^-1) on the early growth and canopy architecture of corn (Zea maize), redroot pigweed (Amaranthus retroflexus L.), velvetleaf (Abutilon theophrasti Medic.), giant foxtail (Setaria faberi Herrm.) and common lambsquarters (Chenopodium album L.). Increasing levels of soil solution N significantly increased relative above-ground plant biomass in a similar fashion for corn and the three broadleaf weeds, but giant foxtail biomass was comparatively unresponsive to higher levels of soil solution N. Differences in canopy architecture were more pronounced than those observed for biomass. Reducing N concentration from 5 mM L^-1 to 2 mM L^-1, resulted in significant height declines for corn (-22%), pigweed (-19%), lambsquarters (-15%), and velvetleaf (-14%). Giant foxtail height was not changed by N treatment, although tiller number was significantly reduced at low N. Diverse growth sensitivities to soil N may in part explain the variability of competitive relationships commonly observed under field conditions. On-going field trials are assessing the capacity of early soil N status to influence the formation of competitive hierarchies and to determine eventual yield loss levels in corn-weed competition. Our results demonstrate that species do not respond uniformly to changes in soil N status and those differential responses must be addressed when considering the impact of soil fertility on competitive outcomes in agricultural systems.