The potential is usually low for fall-applied ammonia to damage corn seed or seedlings. However, if the soil remains dry (and limits nitrification), the ammonia is injected shallow or there is poor soil structure (ammonia placed near the seed location), or the rate of application is high, then it is possible for ammonia damage to occur. The best cure is to inject deep enough with friable soil coverage to get adequate soil separation between the point of ammonia injection and the depth where corn seed will be planted, or offset ammonia bands from future corn rows.

For example, if the injection point is 6-8 in. in depth, the outer edge of the ammonia retention zone (which would be low in ammonia concentration) is 4 in. from the point of injection, and seed is planted at a 2-in. depth directly over the ammonia track, then the seed would be outside the applied ammonia band. Shallower injection, greater movement upward from the injection point, wider knife spacing or higher rates can lead to ammonia being in the seeding area at rates high enough to cause damage.

Bottom line

Be mindful of what is happening at application, especially if soil conditions are not ideal. If you make an application round in the field, and you can still smell ammonia from that application, then you should make adjustments or wait for better conditions. If the soil is breaking into clods, there isn’t good coverage of the knife track with loose soil, and ammonia is escaping (remember your nose tells you if ammonia is escaping; a white vapor is condensed water vapor, not ammonia which is colorless), then stop and either change the way the equipment is working or is set up, or wait until the soil has better structure or moisture.