Info from article says corn roots grow 1" per day. 

Article says 30" row roots meet in the middle at V3 stage. V3 is probably when a lot of sidedress N occurs, or at least around here.

So, why does the Y-drop  method of N placement claim that placing the N at plant base, however laying on the surface, at a later stage is better? 

Can roots be "encouraged" to grow to N placement? I think I'd rather have a bunch of roots growing towards the row center vs concentrating themselves at the plant base.