Ammonia Application Continues

The dry fall has led many growers to apply fall nitrogen in the form of anhydrous ammonia. Soil temperatures have a direct impact on the conversion of fall applied ammonia to nitrate. The rule of thumb of waiting until soil temperatures drop to 50 degrees F is a standard but the conversion from ammonia to nitrate will continue at 50 degrees and below.

 

Conversion only stops when the soil freezes. The rate of conversion slows dramatically but still takes place.  Looking at the Graves Chapple Research Center weather station, the soil temperatures from mid-October were from 60 to 50 degrees. During the first two weeks in November, soil temperatures moved to around 50 degrees.  Soil temperatures from mid-November have bounced around 45 degrees to well into December.

 

The speed of conversion can be predicted somewhat by using the application date and soil temperatures.  In past years with wet springs, we can have the issue of nitrogen losses. However, as we prepare for the next growing season, we should remain flexible to manage nitrogen through the 2013 growing season.

 

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