Ammonia Injury

May 26, 2000
We have received a number of calls describing the classic symptoms of ammonia damage. Nearly all of these problems are coming from west-central Illinoisthe area from Springfield to Quincyone of the driest areas in the state. If you think you have a problem, look for the following conditions:

· Failure to germinatethe seed will either not germinate at all, or the radicle will start to emerge and then die.

· Root burningthe tips of the roots will be brown, and often there will be no root hairs.

· Plants that have emerged may show wilting, purpling, and in some cases eventual death.

· A pattern of injury should be evident. If the ammonia was put on diagonal to the direction of planting, the pattern should be in a diagonal. If the ammonia was put on in the direction of planting and the knife spacing is the same as row spacing, symptoms should be evident in more than one row. Failure to see the symptoms in more than one row does not confirm that it was not ammonia, as it is possible that one knife may have been shallower or may have been delivering more ammonia than the ones beside it.

Why is the damage showing up this season? Ammonia will move in the soil until it finds enough water to convert it to ammonium. Normally, it moves only about 4 inches from the point of injection, but under dry conditions it may move as much as 6 to 8 inches, resulting in some of the ammonia moving into the zone near the seed. Ammonia generally moves in a circular pattern from the point of application, except it will move farther in the soil directly above the injection point, as that soil is looser.

While extremely rare, there has been a report of ammonia damage associated with urea application. Apparently, the field had been chisel-plow 1ed leaving rather deep furrows. Following urea application, the soil was leveled with a field cultivater, resulting in the urea being deposited into a somewhat concentrated band in the bottom of the furrow. Those seeds that were planted in the furrow would have come in contact with ammonia (first product of urea conversion) concentrations that were high enough to inhibit germination and/or root growth. This problem can exist if urea or urea­ammonium nitrate solutions are placed with the seed at planting.--Robert G. Hoeft

Author: Robert Hoeft