1. Ammonia losses are largest when urea is surface applied to wet or damp soil surface followed by drying. Up to 22% of applied urea-N can be lost in 1 week,, > 30% total. Even if the soil temperatures are cold (e.g. 26-35 °F) growers should avoid applying urea to wet or damp soil! 
  2. The 2 applications onto snow had 20-25% total loss.
  3. Applying urea to a dry soil surface is best, but the size of the first precipitation event is determines the amount of  ammonia loss. At least 0.5” rainfall in a single event is needed to move urea into the soil deep enough to minimize or prevent volatilization. Light scattered rain is often not sufficient moisture; it may increase rather than prevent volatilization losses.
  4. Large loss of fertilizer N (e.g. > 30% of applied N rate) can probably be avoided, but losses of 8-15% appear to be quite common in northern Montana. Mid-row or subsurface banding (at least 2" deep) are the best placement methods to minimize losses.
  5. Agrotain® added to urea always reduced losses. It provided two weeks of volatilization protection in acidic soils, but its longevity was greater in calcareous soils (up to eight weeks).
  6. Airdrill seeding after broadcasting urea did not provide sufficient incorporation to mitigate volatilization losses.
  7. Surface broadcast urea for fall-planted crops should be applied in the spring to get the greatest fertilizer N recovery (percentage of applied N recovered). Fertilizer N recovery in winter wheat grain averaged 26, 28 and 37% for late-fall, winter, and spring applications, respectively.
  8. Late-fall and winter applications are more susceptible than spring applications to N volatilization loss. The addition of Agrotain® can mitigate N loss by 60-65%.
  9. Grain protein was higher for spring urea applications than late-fall and winter applications.