AMMONIA LOSS FOLLOWING SURFACE APPLICATION OF UREA FERTILIZER TO UNDRAINED AND DRAINED FORESTED MINEROTROPHIC PEATLAND SITES IN CENTRAL ALBERTA, CANADA

Drainage and urea fertilization of forested peatlands in western Canad a are being contemplated as means for increasing peatland conifer prod uctivity. Surface application of urea-based fertilizers may result in loss of some N by volatilization of NH3. The objective of the present study was to assess the loss of NH3 from undrained and drained peatlan d sites as affected by various N dosages, i.e. 0 (unfertilized), 200 ( N-2) and 400 kg N ha(-1) (N-4), following field broadcast application of urea fertilizer. Losses of NH3 from fertilized plots were higher on the undrained relative to the drained site. Increase in urea-N dosage increased NH3 volatilization from both sites. Most of the NH3 volatil ization losses occurred during the first 9 days after fertilizer appli cation. The precipitation that occurred on day 9 after fertilizer appl ication decreased NH3 volatilization to background levels of unfertili zed plots for the rest of the study period. Net mean losses of NH3 fro m the undrained site were 3% and 4% of applied N for N-2 and N-4, resp ectively. Corresponding losses on the drained site were 0.7% and 7%. T hese magnitudes of loss of N appear to be less important from a forest management point of view.