i am too intrigued by his ultra low use of n to produce the bushels he mentions.    we every year run a trial someplace that has a strip with no n on it. the best i have seen is 125 bu/acre right next to 200+ corn with n applied, so often times the difference is greater.
we do some custom n application and last year a customer raised 200+ corn on fall applied nh3 at 120lbs acre.    also had another customer raise 250+ corn on 140 units of sidedressed nh3.
the 140 unit rate is 60-80 lbs less than this customer has used in the past.   the 120 lb rate is what this customer has always used.  we have also trialed the max rate we see any response, it appears that anything above 230-260, adds no bushels.

pva as far as your variable rate question in a post above, we have been working with a area agronomist on the custom side of things. he has been doing variable rate nitrogen for several years, refining his craft.  and the farmers he consults for are pretty happy with the results.   i could pass along contact info if you would be interested to talk to him.