Drills and air seeders are generally different animals than planters. If you don't understand that, you may make some critical mistakes that will lead to poorly spaced stands that don't emerge uniformly.
That's what Paul Jasa says. He is an Extension ag engineer at the University of Nebraska who has spent three decades working with planter and drill performance in continuous no-till situations.
"You need to look at the drill or air seeder and see that if it is set up for narrow rows, such as 7.5 or 8 inches, there are four times the disc openers compared to a 30-inch row planter. That means you have one-fourth the clearance for residue, and makes doing a good job of spreading chaff and residue in the fall with the combine even more important."
It also means that weight will be a big concern with getting these units to do a good job of planting, Jasa says. The basic operations that must be accomplished are still the same: cut the residue, place seed at a uniform depth, obtain good seed-to-soil contact and then close the trench properly over the seed.
In much of his work in continuous no-till in his own plots and with farmers, Jasa has found that one of the big struggles is often getting enough weight on the drill and in the right places so that it will penetrate and place seed properly when conditions are not perfect.
Some companies have recognized the problem and added extra weight on the unit as it comes from the factory. Weights of some drill models are now considerably heavier than when the original model was released several years ago.
Besides weight it's also important to make sure closing wheels are doing the job, Jasa says. Sometimes there can be drift, and closing wheels may slide to the side of the trench where the seed is, and not firm or break up sidewall compaction correctly. Many have found that the press wheel Case IH made with a narrower running width firmed seed better in the trench. John Deere now manufactures a similar attachment which you can buy instead of their standard, wider closing wheel.