the pelletized lime in lieu of rock filler sounds like a genius idea to me. If it is 13-13-13, then you are getting the same amounts of N, P, and K, in each 50lb bag so they have to be substituting the filler with some sort of pelletized lime. It's actually 19.5 total lbs of fertilizer in 50lbs of 13-13-13 so whomever told you the breakdown of what was in the bag was 20/30 is correct. Win win to me.