One of the most exciting things I've followed in the no-till arena is the potential (emphasize that) for a reduction in N addtion.  As the amount of organic matter in the soil rises, the amount of "natural N" also goes up.  The beauty of this relationship is that more N is minerlized as soil temperature increases and the little critters in the soil kick up their activity and this corresponds quite nicely with when corn needs the most N.  Mother Nature knows what she's doing!!