I've made the drive from Davenport to Des Moines a few times.
I shit you not - the air smelled like manure for a good 2-3 hours. Assuming that's turkey, cattle and hogs, but it was HORRIBLE for almost the whole drive. Finally dissipated about 1/2 hour east of Des Moines. And for some weird reason it's happened the last 4 times I've made the drive, furthering my thoughts that it's always smelled like feces.
To be fair, I've smelled some of those same things up near Wisner, but it lasts about 5 minutes then...DONE.