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Soil Science Society of America Journal Abstract -

Automated Soil Monolith-Flux Chamber System for the Study of Trace Gas Fluxes


This article in SSSAJ

  1. Vol. 61 No. 5, p. 1323-1330
    Received: June 26, 1996

    * Corresponding author(s): k.a.smith@ed.ac.uk
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  1. Petra E. Thomson,
  2. John P. Parker,
  3. Jonathan R. M. Arah,
  4. Helen Clayton and
  5. Keith A. Smith 
  1. Soils Dep., Scottish Agricultural College, School of Agriculture, West Mains Road, Edinburgh EH9 3JG, Scotland
    Inst. of Terrestrial Ecology, Bush Estate, Penicuik, Midlothian EH26 0QB, Scotland
    Inst. of Ecology and Resource Management, Univ. of Edinburgh, School of Agriculture, West Mains Road, Edinburgh EH9 3JG, Scotland



Soils are the major source of atmospheric N2O, and better estimates of fluxes are needed to improve the input to climatic general circulation models. We developed a system in a semicontrolled environment to investigate relationships between fluxes of N2O and controlling variables. It consists of 12 soil monoliths (1-m diam., ≈ 0.6 m deep) in glass fiber casings, the tops of which have been converted into gas flux chambers. These chambers are connected to a gas chromatograph for measurement of N2O and CO2. Gas sampling and analysis is computer controlled and can be done continuously. Temperatures and soil water potential are also recorded continuously. The system has performed reliably since continuous operation began in September 1993. We conducted three experiments, examining the effects of soil water potential, organic matter input, and diurnal temperature variation on N2O fluxes, to illustrate the capabilities of the system. In these experiments, the major emissions of N2O (>800 εg N2O-N m−2 h−1) occurred when the water potential was above −5 kPa. When plant material was incorporated into the soil, a highly significant correlation was found between N2O and CO2 emissions; the N2O emissions showed pronounced diurnal cycles, with the maxima occurring at night, 4 h after the temperature maxima at 0.1-m depth. Data interpretation was greatly aided by the frequency and continuity of measurement.

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