Presentation about NH3 application
Hanna noted the six-inch depth application appears to cause fewer concerns than the four-inch depth that has been more common with the search for speed, although four inches is deep enough in most situations. Iowa State University has done research work with anhydrous ammonia application at 4 inch and 6 inch depths—fall and spring.
Spring application and planting right into a shallow application zone is the biggest concern, especially if the seed is planted right into the area where anhydrous ammonia application has occurred or if the ammonia is applied right over the top of the seed row in a sidedress situation. There was not much affect to the crop until there was a shallow injection in the spring right in the row at higher rates of 160 pounds per acre and more. Plant populations “started to tapper off,” he explained. Plants also came up with ammonia burn.
Application a little off to the side of the row is OK. And GPS positioning for planting is a good way to avoid directly over the top of the anhydrous ammonia injection.
Maintaining a reasonable injection depth is important and four inches is as shallow as an injection should be done. It might be better with spring application to go with the deeper depths, too.
Hanna said, “There is some potential damage with shallow placement. You need to be at least aware of that, and it probably occurs more in spring application or with drier soils and with a high application rate in the seed zone.”