Not too many people likely plant 4 miles per hour- perhaps some in no-till might. More farmers today likely plant at 5 to 6 miles per hour. Results from the Indiana Prairie Farmer Precision Planting plots this year indicate that planting at 4 miles per hour might give you a more uniform stand, but that it won't necessarily give you a better yield.
Purdue University corn specialist Bob Nielsen says the place to start in determining how fast to drive when you plant next spring is your operator's manual, prepared by the company that manufactured the planter. Some planters still perform well at faster speeds than others.
A good practice, he believes, is to try 5 miles per hour if your manual suggests the 5 to 6 miles per hour driving range. Then gradually go faster and see how the planter performs. The trick is taking time to stop and see how the planter is performing.
You're looking for overall population drops, numbers of skips and doubles, and so forth. You can also try out various planting speeds with by having units tested and calibrated before the season starts on test stands.
Some of you may be running Precision Planting's 20/20 Seed Sense monitor. It can give you a better idea of when variability in seed spacing changes as speed increases. Once variation gets beyond acceptable limits, you would want to back down speed to the point were the planter was doing a good job.
Various tests over the years by universities, seed companies and others have generally given the nod to slower relative planting speeds for better spacing and ultimate better performance. However, as Nielsen mentioned, planter accuracy has increased, as improvements continue to be implemented.
Field conditions also play a role. That's one reason no-tillers generally plant slower, since amount of residue encountered and field speed may vary. In the Precision Planting test plots, the plots were planted crosswise to the way the field was tilled. That made for bumpier rides, especially at 6 miles per hour. However, the standard deviation, or variation from perfect, was still within such limits tat yield potential wasn't affected, at least not in this test.
So can you drive your planter 6 miles per hour without looking back? That's not what this test actually proves. It's good only for the conditions where it was tested. Besides, fertilizer or other weight was not a factor here since there was no fertilizer applied with this planter.