5 Tips to avoid anhydrous ammonia damage to corn

Anhydrous ammonia applications shortly after corn planting can injure corn seedlings particularly under cold and dry soil conditions. Separating the corn seed/seedling by either time or distance from anhydrous ammonia applications helps to reduce the risk of injury. 

Anhydrous ammonia burn to corn

Anhydrous ammonia “burn” to corn roots occurs when the corn seedling comes into contact with high concentrations of free ammonia (NH₃). Anhydrous ammonia when injected into the soil is rapidly converted to ammonium (NH₄+) by associating with hydrogen ions. Most hydrogen ions come from water molecules and some come from soil cation exchange sites. When the hydrogen ions leave the water molecule, hydroxyl ions (OH-) are left behind. This reaction temporarily increases the soil pH at the point of injection and allows some free ammonia to exist in the soil which can cause injury or burn (Figure 1). High ammonium concentrations and high pH in the anhydrous band initially slow the conversion of ammonium to nitrate by soil microbes....