Stacks443- I would figure on putting about 2/3 of your nitrogen needs on as preplant NH3 or UAN, whatever is available in your area. I use NH3 because its cheaper and available, I understand some areas can't get it. This nitrogen is going to protected against de-nitrification. Either with N-Serve on the NH3 or Instinct on the UAN. In my opinion, there are no subsitutes. From there I would put 8-10 gal/ ac of UAN with your herbicide pre. That'll give you another 30 lbs. of N, protect that with Agrotain Ultra. Once again, no subsitute. That'll protect you from the Urea part of the UAN from volatalizing. From there I would spread 100 lb/ ac of Urea treated with Agrotain Ultra at V4-V7. Don't go past V8. That would be my final Nitrogen application.
That is my nitrogen management for corn. I wouldn't spread nitrogen after V8 b/c you have to have rain to put that N to work. Spreading Urea at tasseling is quite risky, IMO. If it forgets to rain around tasseling/ grain fill even for 2 weeks, that Urea you put on is gone. Buh-BYE. Additionally, even if it rains and gets it in the soil (saves it from volatilization) but there isn't enough soil moisture to move that N to the roots, boom... no help from it either. Hope all that makes sense.
I love spoon feeding my corn, and so many people claim they don't have time to manage their corn the way I do. My first response is that I love beating their corn yield by 40 bushel/ ac. They hate hearing that. Then I point out that I only had 1 additional pass than them, in regards to nutrient application. Your question about the Urea burning the corn is a good one. But no, it doesn't burn it enough to amount to anything. I know some people that had a wet spring a couple of years ago that were unable to get their preplant N put on, so they decided to just get the corn planted and they would side-dress it with NH3. Well it stayed wet and they were unable to sidedress it, so they spread 435 lbs/ ac of Urea at about V5, and it burned the crap out of it. 2 weeks later it was looking back to normal, it yielded as good or better than the corn in the area.