We received area rains, but growers should carefully consider the soil moisture content when applying anhydrous ammonia. Dry soils can result in losses as the ammonia reacts with the soil.
Ammonia reacts with soil moisture to form ammonium which attaches to the soil. This does not happen immediately but with dryer conditions, happens more slowly. If some of the ammonia does not react, it can escape from the soil. Loss of ammonia gas can take place over time and continue for several days with no soil moisture. Research has shown losses up to 50% under extreme dry conditions.
Also, the physical dryness the soil can affect sealing of the ammonia application. Cloddy soil or no-tilled soils that fail to properly seal will allow the loss of ammonia. It is critical to increase the ammonia placement depth when applying into dry soils. Typically, deeper placement has more moisture which will allow ammonia to react and seal the knife track.
If you smell ammonia escaping the soil during application, you may want to consider waiting for soil moisture conditions to improve. Another option is to use equipment with covering disks or sealing wings to cover the injection slot. Be sure to place ammonia six to eight inches deep.
Also, soil temperatures should be considered before ammonia application. The University of Missouri weather stations across Missouri can give you real time data about soil temperatures at the 6” depth. Currently as of this writing, soil temperatures are in the upper 40s at the St. Joseph weather station site located at the Buchanan County Extension Center. If you are applying ammonia before soil temperatures drop, you may want to consider using a nitrification inhibitor.
For more information, contact Wayne Flanary, Field Specialist in Agronomy, at 816-279-1691, University of Missouri Extension.