Warm Soil Temperatures put Fall Anhydrous Ammonia Applications at Risk By John Lory

Soil temperatures north of I-70 have remained well above normal in the first half of November. The average daily six-inch soil temperature under soybean stubble has been in the mid to upper 50s for much of the period. These temperatures are warm enough to allow significant conversion of anhydrous ammonia to nitrate. Farmers who have already applied anhydrous ammonia need to be aware that a wet winter and spring could lead to substantial losses of fall-applied nitrogen.

Fall nitrogen applications are not recommended until soil temperatures stay well below 50 degrees. Typically this occurs in mid- to late November. This year soil temperatures were still too warm to recommend fall applications of anhydrous ammonia in northern Missouri as of November 15. To track soil temperatures in your region visit the on-line University of Missouri weather resources at http://agebb.missouri.edu/weather/stations/index.htm.

John Lory
Environmental Nutrient Management
573-884-7815