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Comparison of a Forced‐draft Technique to Nitrogen‐15 Recovery for Measuring Ammonia Volatilization Under Field Conditions
Author(s) -
Hargrove W. L.,
Bock B. R.,
Raunikar R. A.,
Urban W. J.
Publication year - 1987
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/sssaj1987.03615995005100010027x
Subject(s) - ammonia volatilization from urea , loam , environmental science , hull , volatilisation , fertilizer , nitrogen , urea , agronomy , soil science , mathematics , chemistry , soil water , materials science , organic chemistry , biology , composite material
Reliable field measurements of NH 3 volatilization are necessary for evaluating N‐fertilizer efficiency for sod crops and conservation crop production systems. This study was conducted to compare NH 3 loss measurements under field conditions using a forced‐draft technique and recovery of urea‐ 15 N. Measurements were made from urea solution applied at a rate of 100 kg N ha −1 to a bare or mulched Cecil sandy loam soil (Typic Hapludult). In an adjacent area, microplots were established to which urea enriched with 15 N was added. Ammonia losses from the bare and mulched soil were 49 and 72% of the applied N by the forced‐draft technique, and 14 and 46% of the applied N by 15 N recovery. The air flow rate with the forced‐draft technique was shown to exceed the actual wind speed near the soil surface 10 and 50% of the time for bare and mulched soil, respectively. These results raise serious questions about the validity and accuracy of the forced‐draft technique. The usefulness of the forced‐draft technique may be limited to relative comparisons of N sources, N rates, and various management practices.