There have been some reports of corn seedlings being damaged from ammonia fertilizer this spring in Iowa—even in fields where the anhydrous ammonia was applied last fall. Ammonia injury has been noted in past springs and it more frequently occurs with shallow placed ammonia, ammonia applied in the spring near the time of planting, or where urea is placed near the seed, and when soil conditions are dry.
In some cases the plant is killed, and in other cases the early root and plant growth can be impacted slightly or severely, says John Sawyer, Iowa State University Extension soil fertility specialist. Damage, potential re-growth, and season-long corn plant development rate can be aggravated by other stresses in combination with ammonia injury, he points out.
How to avoid ammonia burn injury on corn roots
For more information and pictures of this type of damage, you need to read a more in-depth article on the topic, which Sawyer has written and has posted on his Web site. Sawyer discusses why this "ammoinia burn" damage can occur on corn roots, how it occurs and he makes some management suggestions to help farmers avoid this corn injury. Go to www.agronext.iastate.edu/soilfertility/
Sawyer's summary: "Anhydrous ammonia and urea are good N fertilizer sources. With proper management, and help from Mother Nature, most fields do not experience crop injury issues from use of these materials. However, sometimes problems arise due to a variety of reasons. Potential for crop injury can be greatly reduced by not matching corn rows with ammonia tracks and urea bands. Having enough soil separation between the N band and the corn row is the key. So, applying at an angle, having good injection depth, and good soil conditions at application, or use of RTK GPS (real time kinematic GPS) to place bands away from future corn rows—is what you want to do to avoid this injury."
Two examples of corn seedling damage from ammonia.