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Effects of field methods and soil cover on estimating ammonia loss from nitrogen-15-urea

Conference · · Soil Science Society of America Journal; (USA)
OSTI ID:5302196
;  [1]
  1. North Carolina State Univ., Raleigh (USA)

Ammonia loss from urea fertilizers is difficult to measure accurately in the field. In a field study we compared two methods for measuring NH{sub 3} loss from {sup 15}N-urea surface applied to bare and bermudagrass (Cynodon dactylon L.) covered Captina silt loam. The two methods were semi-open chambers and open microplots using {sup 15}N recovery. Labeled urea was applied at 100 kg N ha{sup {minus}1}, and chambers and microplots were shaded and protected from rainfall. Estimates of NH{sub 3} losses from the bare soil after 357 h were 24.6 and 48.0% of the applied N from the semi-open chambers and open microplots, respectively. Estimates of NH{sub 3} losses form the bermudagrass after 357 h were 34.5 and 42.7% of the applied N for the semi-open chambers and open microplots, respectively. In the bermudagrass microplots, 78.6% of the applied {sup 15}N either remained in the plant-thatch layer above the soil or was volatilized 18 h after urea application. Transport and transformations in the soil had little influence on NH{sub 3} loss from bermudagrass plots. These data indicted that measured NH{sub 3} loss from bare soil in semi-open chambers was significantly less than NH{sub 3} loss in open microplots using {sup 15}N recovery techniques. Cumulative NH{sub 3} losses from urea retained on bermudagrass and thatch above the soil were similar in the semi-open chambers and open microplots.

OSTI ID:
5302196
Report Number(s):
CONF-881108--
Journal Information:
Soil Science Society of America Journal; (USA), Journal Name: Soil Science Society of America Journal; (USA) Vol. 52:3; ISSN SSSJD; ISSN 0361-5995
Country of Publication:
United States
Language:
English