"I keep bucking him, but sounds like he's right"
Yea, that sorta sounds like me and my old man... I found as I went on he was usually right, I just hated to admit it. Now we get along a lot better... well most of the time.
"...best way to measure the rates is how?"
I personally never measured my fertilizer output, just set that sucker " 'bout middleways" and rolled on. I would suggest keeping to the lower end of the spectrum though, since 650lb to the acre seems a touch high to me, especially if I'm having to buy the stuff. But in all seriousness, I kept mine set about 1/3 of the way up from the bottom and it seemed to be good enough to give the corn and beans a fine head start. YMMV, of course.