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Design and Ammonia‐Recovery Evaluation of a Wind Speed‐Sensitive Chamber System
Author(s) -
Cabrera M. L.,
Kissel D. E.,
Davis R. C.,
Qafoku N. P.,
Segars W. I.
Publication year - 2001
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2001.6541302x
Subject(s) - wind speed , anemometer , volatilisation , environmental science , ammonia , wind direction , vacuum chamber , meteorology , materials science , chemistry , physics , composite material , organic chemistry
A previously developed system to measure NH 3 volatilization in the field consists of a vacuum pump, volatilization chambers, and acid traps to capture NH 3 The vacuum pump of the system draws air through each chamber at a constant rate, which may be faster or slower than the wind speed outside the chamber. Because wind speed affects NH 3 volatilization, it would be desirable to draw air through the chambers at a wind speed similar to that outside the chambers. The objective of this work was to improve the existing design by adding the capability of adjusting the speed at which air is drawn through each chamber. A hot needle anemometer was placed next to each chamber to measure wind speed at 1 cm above the soil surface. Wind speed was used to adjust an electronic valve so that the rate at which air was drawn through the chamber would match the external wind speed. Three N recovery studies were conducted with a sand–CaCO 3 mixture in the field to determine if the system could be used to obtain quantitative estimates of NH 3 volatilized. The NH 3 volatilized in each study was estimated from (i) the loss of soil inorganic N and (ii) the N captured in the acid traps. In all three studies, the NH 3 volatilized estimated from the acid traps (10–15% of applied N) was not different from the NH 3 volatilized estimated from the loss of soil inorganic N. These results indicate that the system can be used to obtain quantitative measurements of NH 3 volatilized under the conditions of these studies.