Understanding system is key to uniform application of anhydrous ammonia

For uniform application of anhydrous ammonia, it’s important to understand the system you’re using, said an agricultural engineer at University of Missouri’s recent Crop Management Conference in Columbia.

 

Division of flow is often the cause of non-uniform application, said Mark Hanna of Iowa State University Extension.

 

“Because you have not just a liquid but a liquid and gas trying to flow through the system, it can be very challenging to disperse it uniformly,” he said.

 

For producers using an older, conventional open-chamber manifold, Hanna suggests looking at newer systems that might do a better job. However, there are also changes that can be made in the current system.

 

“If you are still using the open-chamber style model, recognize there are different areas of that manifold that will have high and low outlet flows,” Hanna said. “Some people just sequentially hook up hoses to the application ports. That will almost guarantee high and low spots, so mixing and matching the hoses to the outlets rather than sequentially attaching them can help.”

 

Hanna offered additional recommendations: keep hose lengths equal; when using a heat exchange flow controller, match vapor lines with outlet ports that have a lower application rate; and do your homework to fully understand your application system.

 

Hanna says many producers don’t like to use anhydrous ammonia because of safety hazards and the fact that gases boil off as liquid moves through the system and pressure drops.

 

“It makes it a little bit more difficult to distribute that way,” Hanna said. “People are often a little bit nervous about how uniform their distribution is and that is a reason why some change to other forms of nitrogen.”

 

However, because of its high concentration of nitrogen and its lower cost compared to other sources of nitrogen, many people continue to use it, he said.

 

“Respect the material and follow the proper guidelines to be successful,” Hanna said. “There is also a slight possibility of nitrogen loss through shallow application or ammonia burn with plants, but otherwise it is a pretty good product.”

Ammonia Damage to Corn

There is potential for ammonia damage to corn especially in dry springs. The risk will vary with the soil moisture, soil texture, depth of the ammonia placement, and rate injected into the soil, and proximity of the corn seed to the ammonia band.

Ammonia burn can be diagnosed by locating the knife track and where the seed was planted into this track. The damaged roots will be brown and look as if they were burned. They will not grow into the ammonia zone until later. The corn plants may also take on a wilted appearance as root system is limited. If the seed is directly in the zone and ammonia has leaked upward, the seed may start to germinate but will die.

When ammonia is injected into the soil, it moves outward from the injection point. This forms an oval or circular shape of ammonia release in the soil. The greatest concentration is at the point of release and lessens outward from this point.

Situations which growers should be aware of are conditions which may cause ammonia not to seal. This may occur on coarse-textured soils or soils which are too wet or dry. Ammonia will move back up the knife slot if not properly sealed and have a higher potential of injury as seed may be placed in this zone.

Winged sealers immediately above the outlet of the knife can help prevent ammonia movement upward. Also, be sure to place ammonia deep enough into the soil. Injury comes from free ammonia coming in contact with the seed and roots.

For more information, contact Wayne Flanary at 660-446-3724 or Heather Benedict at 660-425-6434, Regional Agronomists, University of Missouri Extension.

Careful When Planting Corn after Ammonia Application

Careful When Planting Corn after Ammonia Application

As growers plant corn after applying anhydrous ammonia, care should be taken. Most ammonia injury to corn occurs during a dry spring, however, wet soil conditions can lead to ammonia injury to seedling corn also.

A rule of thumb is to wait seven to ten days after ammonia application before planting. If one needs to plant quickly, then if ammonia placed at the correct depth in good moisture. The key is placing the ammonia at six to eight inches deep in the soil and not too shallow.

With any ammonia application, it is best not to plant directly on top of the ammonia fertilizer injection band. If any free ammonia moves upward because of wet side walls or air pockets, then this can move upward and come in contact with the new corn seedling causing injury. Apply ammonia at an angle in the field so a planted row will not be directly on top of the ammonia band.

When ammonia is injected into the soil, it will create a zone of concentration of approximately four-inches in radius. The highest concentration will be where the ammonia left the knife. The lowest the further away from the injection point.

Ammonia moves further away from the injection point in dry soil and in sandy soils. Instead of being a circular band, it can be oblong, moving upward. Also, if the injection knife smears the sidewall if the soil is too wet, then ammonia can move back up the knife slot. Another related situation would be ammonia moving up as the soil dries and opens up the knife track.

Diagnosis of corn ammonia injury is lack of corn emergence over the knife track or corn seedling roots looking like they have been burnt. If there is injury, there will be a distinct pattern wherever the row crosses the knife track or follows.

For more information, contact Wayne Flanary at 660-446-3724 or Heather Benedict at 660425-6434, Regional Agronomists, University of Missouri Extension.