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Continuous Measurements of Belowground Nitrous Oxide Concentrations
Author(s) -
Drewitt Gordon,
Warland Jon S.
Publication year - 2007
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/sssaj2005.0410
Subject(s) - nitrous oxide , snowmelt , trace gas , environmental science , flux (metallurgy) , environmental chemistry , snow , nutrient , greenhouse gas , carbon dioxide , atmosphere (unit) , gas analyzer , nitrogen , chemistry , hydrology (agriculture) , atmospheric sciences , soil science , meteorology , ecology , geology , physics , geotechnical engineering , organic chemistry , biology
Nitrous oxide released from soil is a concern since it can act as a potential atmospheric pollutant and it represents a loss of N from the soil. To better understand the factors controlling N 2 O production and transport, we developed a system to obtain continuous measurements from below the soil surface. The sampling system pulls small volumes of soil gas from buried sample probes through a tunable diode laser trace gas analyzer. The advantage of this system is that it measures concentrations spectroscopically, allowing regular, continuous measurements. This provides it with the distinct advantage of being able to capture short‐term changes in gas concentrations that may be important for nutrient and greenhouse gas budgeting. Furthermore, the system is relatively simple to install and could be integrated into existing field measurements of trace gas flux. Measurements of belowground N 2 O concentrations were obtained during the spring thaw from buried probes in a conventionally tilled field that was planted in soybean [ Glycine max (L.) Merr.] the previous summer. Measurements showed that belowground N 2 O concentrations at the 25‐cm depth varied between 65 and 85 μmol mol −1 before snowmelt. After melting of the snow and the beginning of the soil thawing, N 2 O concentrations decreased to a value generally <1 μmol mol −1 During this period when belowground N 2 O concentrations were near atmospheric values, wind speed influenced concentrations, possibly through a pressure pumping effect.