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MEASUREMENT OF BI-DIRECTIONAL AMMONIA FLUXES OVER SOYBEAN USING MODIFIED BOWEN-RATIO TECHNIQUE
Citation:
WALKER, JOHNT T., W. ROBARGE, Y. WU, AND T. MEYERS. MEASUREMENT OF BI-DIRECTIONAL AMMONIA FLUXES OVER SOYBEAN USING MODIFIED BOWEN-RATIO TECHNIQUE. AGRICULTURAL AND FOREST METEOROLOGY. Elsevier Science Ltd, New York, NY, 138(1-4):54-68, (2006).
Description:
Measurements of bi-directional ammonia exchange over a fertilized soybean canopy are presented for an 8-week period during the summer of 2002. The modified Bowne-ratio approach was used to determine fluxes from vertical NH3 and temperature gradients in combination with eddy covariance heat fluxes. The measurement site is located on the Coastal Plain of North Carolina in an area of high NH3 emissions from animal production and fertilizer use. Deposition velocities were, on average, higher during the day and nighttime values were largest when the canopy was wet. Measured deposition velocities indicate a large canopy resistance which is likely the result of very dry conditions. Dry deposition of NH3 accounted for approximately 0.3% of corp nitrogen requirements.