Fall NH3 in Dry Weather

Oct 24, 2022

I have been asked multiple times this fall if NH3 will seal this fall with the dry weather we have been experiencing. I found the following clip in an Iowa State University Extension publication that answers this question well: 

“Yes. Dry soil can hold ammonia. Even air-dried soil contains some moisture, although quite low. Ammonia dissolves readily in water, but it is held or retained in soil by clay and organic matter. The problem with dry soil and low moisture is that soil moisture is needed to temporarily hold (“go into solution”) the ammonia so it can become attached to clay or organic matter as ammonium. If dry soils are cloddy and do not seal properly, the ammonia can be lost at injection, or seep through the large pores between clods after application. Therefore, proper depth of injection and good soil coverage are a must for application into dry soils. Wing sealers immediately above the outlet port on the knife can help close the knife track, limit the size of the retention zone, and reduce vertical movement of ammonia. Closing disks can reduce ammonia loss by covering up the injection track with soil that traps the ammonia as it moves to the soil surface.”

Nitrogen stabilizers will also be helpful this fall with retaining our nitrogen in the soil. Function N is a relatively inexpensive peace of mind.

There is one other issue that many may experience this fall until we receive some rainfall. The dry ground is extremely hard and will be difficult to pull a toolbar through. It will take a lot of fuel and risk tearing up application equipment. So while the NH3 will stay in your soil, the problem might be getting it applied to begin with.
Talk to your local SFG agronomist to discuss your fall NH3 application needs and get your stabilizer added.