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Volatilization and foliar recapture of ammonia following spring and fall application of nitrogen-15 urea to a Douglas-fir ecosystem

Conference · · Soil Science Society of America Journal; (USA)
OSTI ID:5302152
Seasonal effects on the volatilization and vegetal recapture of NH{sub 3} following application of pelleted {sup 15}N urea to 200 kh N ha{sup {minus}1} to a 40- yr-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) ecosystem were investigated. Volatilization totalled 14 and 0.7% of applied N in spring and fall, respectively, and the difference appeared to be related to precipitation patterns following fertilization. Volatilization was generally enhanced by small spring rainfalls while depressed by larger fall rains. The isotopic abundance of evolved NH{sub 3} fluctuated from > 90 to < 10% of that of the fertilizer source. These fluctuations reflected the role of precipitation in the regulation of special heterogeneity of urea and urease in soil. Under spring conditions NH{sub 3} was recaptured by potted Douglas-fir seedlings. Seedlings at 10 cm above the forest floor captured 16 times as much NH{sub 3} as seedlings positioned at the 150-cm elevation. Labelled N was distributed among seedling tissues in the order: current foliage > 1-year-old foliage > roots which is consistent with anabolic incorporation and translocation. This mechanism may have a significant role in plant nutrition when conditions favorable to NH{sub 3} volatilization follow urea fertilization.
OSTI ID:
5302152
Report Number(s):
CONF-881108--
Conference Information:
Journal Name: Soil Science Society of America Journal; (USA) Journal Volume: 52:3
Country of Publication:
United States
Language:
English