Work with a farmer here who had run one spike and one rubber closing wheel.  He also banded some fertilizer 2 inches off the seed slot.  Well, when he got to checking fields he noticed a definite difference in the corn rows some being taller and greener.  He started counting the rows and then went back to check his planter.  When they plumbed up the fert tubes they didn't pay any attention to which side it came down on relative to the closing wheels.  The rows that were taller and greener were the ones where the fert. was put on next to the spiked closing wheel where as the others came down to the rubber tire side.  Would assume that the roots were able to penetrate the sidewalls and get to the starter better.  Unfortunately he never did any digging to confirm this. 

Your results are very interesting as well.  Thanks for sharing.