50 pounds of UAN as a broadcast spray will really make the wheat sick from leaf burn.

Some people out here do it, but generally only when the wheat is very small.  Putting a humic acid product with it can reduce the burn somewhat, but it doesn't work miracles.

Personally, 20 pounds of N as UAN broacast sprayed is the most injury I can tolerate.  Streaming the N on and then broadcasting the weed control in a second pass is really the better way from a crop health standpoint.