Careful When Planting Corn after Ammonia Application

Careful When Planting Corn after Ammonia Application

As growers plant corn after applying anhydrous ammonia, care should be taken. Most ammonia injury to corn occurs during a dry spring, however, wet soil conditions can lead to ammonia injury to seedling corn also.

A rule of thumb is to wait seven to ten days after ammonia application before planting. If one needs to plant quickly, then if ammonia placed at the correct depth in good moisture. The key is placing the ammonia at six to eight inches deep in the soil and not too shallow.

With any ammonia application, it is best not to plant directly on top of the ammonia fertilizer injection band. If any free ammonia moves upward because of wet side walls or air pockets, then this can move upward and come in contact with the new corn seedling causing injury. Apply ammonia at an angle in the field so a planted row will not be directly on top of the ammonia band.

When ammonia is injected into the soil, it will create a zone of concentration of approximately four-inches in radius. The highest concentration will be where the ammonia left the knife. The lowest the further away from the injection point.

Ammonia moves further away from the injection point in dry soil and in sandy soils. Instead of being a circular band, it can be oblong, moving upward. Also, if the injection knife smears the sidewall if the soil is too wet, then ammonia can move back up the knife slot. Another related situation would be ammonia moving up as the soil dries and opens up the knife track.

Diagnosis of corn ammonia injury is lack of corn emergence over the knife track or corn seedling roots looking like they have been burnt. If there is injury, there will be a distinct pattern wherever the row crosses the knife track or follows.

For more information, contact Wayne Flanary at 660-446-3724 or Heather Benedict at 660425-6434, Regional Agronomists, University of Missouri Extension.