I have grown 180 bu corn after applying 130 lb of N applied in early March and was then flooded early May. Corn looked great all season. I have grown 125 bu corn after applying 130 lbs N late March and was flooded about half of May(it rained 28 inches in 4 weeks) and then again for a couple of days in June.  Rye planted after corn looked like it was really short on N. 

NH3 requires water and oxygen to convert to nox, along with time and some heat. NH4 will not leach or convert to N2 without first being converted to nox. nzone kills the bacteria that is required for the conversion from NH4 to nox.  If the nzone did not keep most or all in the NH4 form for the 2 to 3 weeks that you needed it to, then you should stop using it. 

I would not add more N.