When considering fall application of anhydrous ammonia make sure that the soil temperature at the 4” level is 50°F or less mid-morning several days before application and the weather forecast indicates it will be trending downward.  Cooler soils minimize microbial activity slowing the conversion of ammonium-N to nitrate-N.  By keeping the applied N in this form it can be held by the soils cation exchange sites.  It is also wise to use a nitrification inhibitor with fall anhydrous ammonia.  Nitrification inhibitors, such as N-Serve™ or Centuro™, will delay conversion of ammonium-N to nitrate-N over several days to weeks, depending upon the soil temperature and moisture at the time of application.  By using an inhibitor in the fall, when soils are cool, it delays most of the nitrification until the spring of the next year, closer to crop uptake and microbial need for mineralization of nitrogen from soil organic matter. 

If soil conditions are dry at the time of application, make a pass across the field, then stop and walk across the area where anhydrous ammonia was applied.  If there is a strong odor of ammonia, consider suspending application until soil conditions are more favorable for the soil to seal behind the applicator.  Always avoid fall applications to coarse-textured soils or soils low in organic matter as these soils have low cation exchange capacities resulting in a lower holding capacity for ammonium. In areas where soils that tend to cool down late into the fall and warm up early in the spring, such as soils south of Route 16 in Illinois, avoid application until spring closer to crop need.   

Consider promoting a nitrogen management system plan.  For corn, rather than applying all the nitrogen needs in the fall or as an early spring application, develop a nitrogen management plan that provides nitrogen to the corn crop incrementally. To accomplish this utilize the 4R approach; right source, right rate, right time, and the right place.  Multiple years of MiField applied research trials has demonstrated a significant yield advantage when using this approach to manage nitrogen.  We found that by increasing the number of applications, growers reduce their risk of losing N to environmental changes. Depending on the environment, split applications may reduce loss and increase the nitrogen utilization by the crop.  Applying nitrogen in a 2 pass system yielded an average increase of 6.8 bu/acre compared to standard practices.

When using nitrification inhibitors avoid tilling the ground following the application of stabilized nitrogen sources as this may affect the ammonium conversion to nitrate.  Once applied, a protective zone is established around the anhydrous ammonia which minimizes the ability of soil microbes to convert ammonium to nitrate. Tillage can destroy this “protective zone” exposing the applied N to active populations of microbes. If tillage is unavoidable, fields with adequate moisture can be tilled within three or four days following anhydrous ammonia application, keeping in mind that where an inhibitor was used a dilution effect can occur.  

  

Pay close attention to application equipment configuration, its condition and safety.  Consider placing manifold plugs directly across from where the anhydrous enters the manifold.  Greater flow of anhydrous ammonia will occur on the opposite side of the inlet.  On manifolds where the inlet is on the top or bottom and centered, distribute plugs evenly around the manifold.  Take time and check the inner surface of manifold hose barbs for any blockage or residue build-up.  Check both old and new anhydrous knives for metal “burrs” in the discharge tube.  These small pieces of metal can reduce anhydrous flow at or to the knife.  FS Companies can supply farmers with the proper protective goggles and rubber gloves and each anhydrous ammonia tank is equipped with a properly placed, fresh source of water.  Make an effort to have each knives anhydrous ammonia delivery tube the same length.  Different hose lengths will have an impact on the amount of liquid ammonia reaching the soil.  BE CAUTIOUS WHEN CHECKING HOSES!  Coiled hoses tend to hold liquid anhydrous ammonia even though the regulator is open.  Moving a coiled hose containing liquid anhydrous ammonia may result in a quick release of anhydrous ammonia vapor that can cause burns or inhalation injury and even death.  Always remain alert, attentive and practice active safety when around anhydrous ammonia.