I'm not sure on either count. however my understanding is that the standard practice is to run it immediately after spreading to minimize losses. The impression I got it that the sooner and faster you run the better the incorporation action and 8 mph is the goal. sort of like the Pluribus turbulent transition point at about 5 mph. I would bet with manure there is still a fair amount on or near the surface but doubt it would run off much.

Jim at Dawn.