You may typically be applying nitrogen at this time, but since this has not been a typical spring, University of Illinois Extension crop specialist Emerson Nafziger suggests letting the crop maturity and soil condition determine the timing of the N, rather than the calendar.  Read his latest nitrogen thoughts at the University of Illinois Extension site.

Your typical nitrogen application may be much more than the corn can use, says Nafziger, because crop conditions this spring have reduced the yield potential, and may continue to reduce yield potential. In that case, Nafziger says no amount of nitrogen will make up the shortfall, and it is only a waste of money to apply an excess of nitrogen.