If a Division II school beat the number one ranked basketball team in Division I at the start of the season, would you bet on the Division II school to win again at those same odds? Probably not. More than likely tremendous effort or quirky circumstances contributed to the upset. You can do it once occasionally – it's very hard to do it twice.
In the same light there could be two historic drought years back to back in the same area of the Corn Belt, but it's highly unlikely. A repeat of 2012 and what worked best in 2012 is probably information to file away and recall if the probability of a drought year is high at some point in the future. In the meantime, if you back off to 24,000 from 30,000 kernels per acre for seeding rate because hybrids did best at 24,000 in 2012, you could be leaving some 40 bushels per acre on the table if 2013 is not like 2012. Odds heavily favor that it will be different and not the same.
Where did we get the 40 bushel estimate that you might sacrifice by reducing stands based on 2012? Chances are that the 2013 season will not be like 2012. Odds heavily favor that it will be different and not the same.
Agronomists estimate that each 1,000 ears are worth about 7 bushels per acre. If you've got 6,000 fewer plants, that would account, in theory, for 42 fewer bushels per acre.
Instead, most farmers say they're going back with what got them here – rates of 30 to 34,000 seeds per acre. What counts is plants per acre. Adjust your seeding rate based on the emergence and germination you expect. If it's quality seed and you have your planter tuned-up accordingly, there shouldn't be much drop-off between seeding rate and actual plant populations at harvest in 2013.