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Measurement of ammonia emission after liquid manure application: II. Comparison of the wind tunnel and the IHF method under field conditions
Author(s) -
Mannheim Thomas,
Braschkat Jörg,
Marschner Horst
Publication year - 1995
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.19951580302
Subject(s) - wind tunnel , hypersonic wind tunnel , wind speed , environmental science , volatilisation , wind direction , supersonic wind tunnel , atmospheric sciences , meteorology , chemistry , physics , mechanics , organic chemistry
A wind tunnel was constructed for measurement of NH 3 − N volatilization after application of liquid manure. It combines the advantages of micrometeorological field methods with those of customary wind tunnel methods. The wind tunnel, as specified in part I ( Braschkat et al., 1993), is characterized by: ‐the same (or higher) reliability of results as in field measurement by the IHF method (Integrated Horizontal Flux, also known as Mass Balance)‐universal applicability independent of topographical conditions‐a higher temporal and spatial density of experiments compared to micrometeorological methodsThe reliability of the NH 3 − N measurements obtained by the wind tunnel was tested under controlled conditions in a greenhouse (calibration) as well as under field conditions by direct comparison with the IHF method. The rate of recovery of NH 3 − N inserted into the wind tunnel is almost 100 % (± 3 %). In field experiments, no differences between the measurements of the wind tunnel and the IHF method were observed under standard conditions. The higher precision in the determination of the NH 3 − N background concentration with the wind tunnel resulted in a higher accuracy in measurements of the time course of NH 3 − N emissions. Intensity and timing of precipitation may cause an overestimation of NH 3 − N volatilization by the wind tunnel. In contrast to the IHF method. NH 3 − N emissions can be measured with the wind tunnel at wind speeds below 1 m s −1 at 2 m height. No reliable data were obtained with the wind tunnel at wind speeds below 0.3 m s −1 in 0.3 m height.