Cold & Wet weather slows fall NH3 application

Fall NH3 #1Over the last two weeks we have seen a lot of Fall Anhydrous Ammonia knifed in with N-Serve. On medium to heavy soils this is a nice way to ease the work load during the spring rush for many producers. However the 1.3″ of rain we received over the last 4 to 5 days and the cold temperatures rolling in (16 degrees predicted for tonight) have all but stopped the fall applications of NH3 or 82-0-0.  I hope they changed the extended forecast to allow for some more fall field work and application. 

I often get asked how long does the N-Serve protect my NH3 in the soil, and the truth is there is no standard answer.  A lot of it has to do with soil temperature.  I attached a quote from Dow Agrosciences to help with this question. Please stay safe out there this fall!                — Rob Shields


Q. How long does N-Serve protect nitrogen (N) at the root zone?

A. Historically, N-Serve applied in the fall has provided approximately 90 days of effectiveness, with that effectiveness declining over time. N-Serve is designed to slow the conversion of anhydrous ammonia into the nitrate form when soil temperatures rise above 40°F. This soil temperature is significant because the soil bacteria that break down anhydrous ammonia into nitrates become active at this temperature. If soil temperatures are below 40°F, the soil bacteria become inactive and the anhydrous ammonia is not converted into nitrates.

If you’ve applied anhydrous ammonia with N-Serve in the fall, simple counting can help you determine roughly how long N-Serve will protect your N the following spring. Just count the number of days from application until the soil temperature reaches 40°F and then stop counting. Start counting days again when the soil warms back up to 40°F.

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